just make const char iname[] the last member and compare name->name with
name->iname instead of checking name->separate
We need to make sure that out-of-line name doesn't end up allocated adjacent
to struct filename refering to it; fortunately, it's easy to achieve - just
allocate that struct filename with one byte in ->iname[], so that ->iname[0]
will be inside the same object and thus have an address different from that
of out-of-line name [spotted by Boqun Feng <boqun.feng@gmail.com>]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Convert the following where appropriate:
(1) S_ISLNK(dentry->d_inode) to d_is_symlink(dentry).
(2) S_ISREG(dentry->d_inode) to d_is_reg(dentry).
(3) S_ISDIR(dentry->d_inode) to d_is_dir(dentry). This is actually more
complicated than it appears as some calls should be converted to
d_can_lookup() instead. The difference is whether the directory in
question is a real dir with a ->lookup op or whether it's a fake dir with
a ->d_automount op.
In some circumstances, we can subsume checks for dentry->d_inode not being
NULL into this, provided we the code isn't in a filesystem that expects
d_inode to be NULL if the dirent really *is* negative (ie. if we're going to
use d_inode() rather than d_backing_inode() to get the inode pointer).
Note that the dentry type field may be set to something other than
DCACHE_MISS_TYPE when d_inode is NULL in the case of unionmount, where the VFS
manages the fall-through from a negative dentry to a lower layer. In such a
case, the dentry type of the negative union dentry is set to the same as the
type of the lower dentry.
However, if you know d_inode is not NULL at the call site, then you can use
the d_is_xxx() functions even in a filesystem.
There is one further complication: a 0,0 chardev dentry may be labelled
DCACHE_WHITEOUT_TYPE rather than DCACHE_SPECIAL_TYPE. Strictly, this was
intended for special directory entry types that don't have attached inodes.
The following perl+coccinelle script was used:
use strict;
my @callers;
open($fd, 'git grep -l \'S_IS[A-Z].*->d_inode\' |') ||
die "Can't grep for S_ISDIR and co. callers";
@callers = <$fd>;
close($fd);
unless (@callers) {
print "No matches\n";
exit(0);
}
my @cocci = (
'@@',
'expression E;',
'@@',
'',
'- S_ISLNK(E->d_inode->i_mode)',
'+ d_is_symlink(E)',
'',
'@@',
'expression E;',
'@@',
'',
'- S_ISDIR(E->d_inode->i_mode)',
'+ d_is_dir(E)',
'',
'@@',
'expression E;',
'@@',
'',
'- S_ISREG(E->d_inode->i_mode)',
'+ d_is_reg(E)' );
my $coccifile = "tmp.sp.cocci";
open($fd, ">$coccifile") || die $coccifile;
print($fd "$_\n") || die $coccifile foreach (@cocci);
close($fd);
foreach my $file (@callers) {
chomp $file;
print "Processing ", $file, "\n";
system("spatch", "--sp-file", $coccifile, $file, "--in-place", "--no-show-diff") == 0 ||
die "spatch failed";
}
[AV: overlayfs parts skipped]
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
In order to ensure that filenames are not released before the audit
subsystem is done with the strings there are a number of hacks built
into the fs and audit subsystems around getname() and putname(). To
say these hacks are "ugly" would be kind.
This patch removes the filename hackery in favor of a more
conventional reference count based approach. The diffstat below tells
most of the story; lots of audit/fs specific code is replaced with a
traditional reference count based approach that is easily understood,
even by those not familiar with the audit and/or fs subsystems.
CC: viro@zeniv.linux.org.uk
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Enable recording of filenames in getname_kernel() and remove the
kludgy workaround in __audit_inode() now that we have proper filename
logging for kernel users.
CC: viro@zeniv.linux.org.uk
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
a) make it accept ERR_PTR() as filename (and return its PTR_ERR() in that case)
b) make it putname() the sucker in the end otherwise
simplifies life for callers...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
There are several areas in the kernel that create temporary filename
objects using the following pattern:
int func(const char *name)
{
struct filename *file = { .name = name };
...
return 0;
}
... which for the most part works okay, but it causes havoc within the
audit subsystem as the filename object does not persist beyond the
lifetime of the function. This patch converts all of these temporary
filename objects into proper filename objects using getname_kernel()
and putname() which ensure that the filename object persists until the
audit subsystem is finished with it.
Also, a special thanks to Al Viro, Guenter Roeck, and Sabrina Dubroca
for helping resolve a difficult kernel panic on boot related to a
use-after-free problem in kern_path_create(); the thread can be seen
at the link below:
* https://lkml.org/lkml/2015/1/20/710
This patch includes code that was either based on, or directly written
by Al in the above thread.
CC: viro@zeniv.linux.org.uk
CC: linux@roeck-us.net
CC: sd@queasysnail.net
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
In preparation for expanded use in the kernel, make getname_kernel()
more useful by allowing it to handle any legal filename length.
Thanks to Guenter Roeck for his suggestion to substitute memcpy() for
strlcpy().
CC: linux@roeck-us.net
CC: viro@zeniv.linux.org.uk
CC: linux-fsdevel@vger.kernel.org
Signed-off-by: Paul Moore <pmoore@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull vfs pile #2 from Al Viro:
"Next pile (and there'll be one or two more).
The large piece in this one is getting rid of /proc/*/ns/* weirdness;
among other things, it allows to (finally) make nameidata completely
opaque outside of fs/namei.c, making for easier further cleanups in
there"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
coda_venus_readdir(): use file_inode()
fs/namei.c: fold link_path_walk() call into path_init()
path_init(): don't bother with LOOKUP_PARENT in argument
fs/namei.c: new helper (path_cleanup())
path_init(): store the "base" pointer to file in nameidata itself
make default ->i_fop have ->open() fail with ENXIO
make nameidata completely opaque outside of fs/namei.c
kill proc_ns completely
take the targets of /proc/*/ns/* symlinks to separate fs
bury struct proc_ns in fs/proc
copy address of proc_ns_ops into ns_common
new helpers: ns_alloc_inum/ns_free_inum
make proc_ns_operations work with struct ns_common * instead of void *
switch the rest of proc_ns_operations to working with &...->ns
netns: switch ->get()/->put()/->install()/->inum() to working with &net->ns
make mntns ->get()/->put()/->install()/->inum() work with &mnt_ns->ns
common object embedded into various struct ....ns
This patchset adds execveat(2) for x86, and is derived from Meredydd
Luff's patch from Sept 2012 (https://lkml.org/lkml/2012/9/11/528).
The primary aim of adding an execveat syscall is to allow an
implementation of fexecve(3) that does not rely on the /proc filesystem,
at least for executables (rather than scripts). The current glibc version
of fexecve(3) is implemented via /proc, which causes problems in sandboxed
or otherwise restricted environments.
Given the desire for a /proc-free fexecve() implementation, HPA suggested
(https://lkml.org/lkml/2006/7/11/556) that an execveat(2) syscall would be
an appropriate generalization.
Also, having a new syscall means that it can take a flags argument without
back-compatibility concerns. The current implementation just defines the
AT_EMPTY_PATH and AT_SYMLINK_NOFOLLOW flags, but other flags could be
added in future -- for example, flags for new namespaces (as suggested at
https://lkml.org/lkml/2006/7/11/474).
Related history:
- https://lkml.org/lkml/2006/12/27/123 is an example of someone
realizing that fexecve() is likely to fail in a chroot environment.
- http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=514043 covered
documenting the /proc requirement of fexecve(3) in its manpage, to
"prevent other people from wasting their time".
- https://bugzilla.redhat.com/show_bug.cgi?id=241609 described a
problem where a process that did setuid() could not fexecve()
because it no longer had access to /proc/self/fd; this has since
been fixed.
This patch (of 4):
Add a new execveat(2) system call. execveat() is to execve() as openat()
is to open(): it takes a file descriptor that refers to a directory, and
resolves the filename relative to that.
In addition, if the filename is empty and AT_EMPTY_PATH is specified,
execveat() executes the file to which the file descriptor refers. This
replicates the functionality of fexecve(), which is a system call in other
UNIXen, but in Linux glibc it depends on opening "/proc/self/fd/<fd>" (and
so relies on /proc being mounted).
The filename fed to the executed program as argv[0] (or the name of the
script fed to a script interpreter) will be of the form "/dev/fd/<fd>"
(for an empty filename) or "/dev/fd/<fd>/<filename>", effectively
reflecting how the executable was found. This does however mean that
execution of a script in a /proc-less environment won't work; also, script
execution via an O_CLOEXEC file descriptor fails (as the file will not be
accessible after exec).
Based on patches by Meredydd Luff.
Signed-off-by: David Drysdale <drysdale@google.com>
Cc: Meredydd Luff <meredydd@senatehouse.org>
Cc: Shuah Khan <shuah.kh@samsung.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rich Felker <dalias@aerifal.cx>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
All callers of path_init() proceed to do the identical cleanup when
they are done with nameidata. Don't open-code it...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull VFS fixes from Al Viro:
"A bunch of assorted fixes, most of them followups to overlayfs merge"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
ovl: initialize ->is_cursor
Return short read or 0 at end of a raw device, not EIO
isofs: don't bother with ->d_op for normal case
isofs_cmp(): we'll never see a dentry for . or ..
overlayfs: fix lockdep misannotation
ovl: fix check for cursor
overlayfs: barriers for opening upper-layer directory
rcu: Provide counterpart to rcu_dereference() for non-RCU situations
staging: android: logger: Fix log corruption regression
The man page for open(2) indicates that when O_CREAT is specified, the
'mode' argument applies only to future accesses to the file:
Note that this mode applies only to future accesses of the newly
created file; the open() call that creates a read-only file
may well return a read/write file descriptor.
The man page for open(2) implies that 'mode' is treated identically by
O_CREAT and O_TMPFILE.
O_TMPFILE, however, behaves differently:
int fd = open("/tmp", O_TMPFILE | O_RDWR, 0);
assert(fd == -1);
assert(errno == EACCES);
int fd = open("/tmp", O_TMPFILE | O_RDWR, 0600);
assert(fd > 0);
For O_CREAT, do_last() sets acc_mode to MAY_OPEN only:
if (*opened & FILE_CREATED) {
/* Don't check for write permission, don't truncate */
open_flag &= ~O_TRUNC;
will_truncate = false;
acc_mode = MAY_OPEN;
path_to_nameidata(path, nd);
goto finish_open_created;
}
But for O_TMPFILE, do_tmpfile() passes the full op->acc_mode to
may_open().
This patch lines up the behavior of O_TMPFILE with O_CREAT. After the
inode is created, may_open() is called with acc_mode = MAY_OPEN, in
do_tmpfile().
A different, but related glibc bug revealed the discrepancy:
https://sourceware.org/bugzilla/show_bug.cgi?id=17523
The glibc lazily loads the 'mode' argument of open() and openat() using
va_arg() only if O_CREAT is present in 'flags' (to support both the 2
argument and the 3 argument forms of open; same idea for openat()).
However, the glibc ignores the 'mode' argument if O_TMPFILE is in
'flags'.
On x86_64, for open(), it magically works anyway, as 'mode' is in
RDX when entering open(), and is still in RDX on SYSCALL, which is where
the kernel looks for the 3rd argument of a syscall.
But openat() is not quite so lucky: 'mode' is in RCX when entering the
glibc wrapper for openat(), while the kernel looks for the 4th argument
of a syscall in R10. Indeed, the syscall calling convention differs from
the regular calling convention in this respect on x86_64. So the kernel
sees mode = 0 when trying to use glibc openat() with O_TMPFILE, and
fails with EACCES.
Signed-off-by: Eric Rannaud <e@nanocritical.com>
Acked-by: Andy Lutomirski <luto@amacapital.net>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In an overlay directory that shadows an empty lower directory, say
/mnt/a/empty102, do:
touch /mnt/a/empty102/x
unlink /mnt/a/empty102/x
rmdir /mnt/a/empty102
It's actually harmless, but needs another level of nesting between
I_MUTEX_CHILD and I_MUTEX_NORMAL.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This adds a new RENAME_WHITEOUT flag. This flag makes rename() create a
whiteout of source. The whiteout creation is atomic relative to the
rename.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Whiteout isn't actually a new file type, but is represented as a char
device (Linus's idea) with 0/0 device number.
This has several advantages compared to introducing a new whiteout file
type:
- no userspace API changes (e.g. trivial to make backups of upper layer
filesystem, without losing whiteouts)
- no fs image format changes (you can boot an old kernel/fsck without
whiteout support and things won't break)
- implementation is trivial
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
It's already duplicated in btrfs and about to be used in overlayfs too.
Move the sticky bit check to an inline helper and call the out-of-line
helper only in the unlikly case of the sticky bit being set.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
We need to be able to check inode permissions (but not filesystem implied
permissions) for stackable filesystems. Expose this interface for overlayfs.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Add a new inode operation i_op->dentry_open(). This is for stacked filesystems
that want to return a struct file from a different filesystem.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Pull vfs updates from Al Viro:
"The big thing in this pile is Eric's unmount-on-rmdir series; we
finally have everything we need for that. The final piece of prereqs
is delayed mntput() - now filesystem shutdown always happens on
shallow stack.
Other than that, we have several new primitives for iov_iter (Matt
Wilcox, culled from his XIP-related series) pushing the conversion to
->read_iter()/ ->write_iter() a bit more, a bunch of fs/dcache.c
cleanups and fixes (including the external name refcounting, which
gives consistent behaviour of d_move() wrt procfs symlinks for long
and short names alike) and assorted cleanups and fixes all over the
place.
This is just the first pile; there's a lot of stuff from various
people that ought to go in this window. Starting with
unionmount/overlayfs mess... ;-/"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (60 commits)
fs/file_table.c: Update alloc_file() comment
vfs: Deduplicate code shared by xattr system calls operating on paths
reiserfs: remove pointless forward declaration of struct nameidata
don't need that forward declaration of struct nameidata in dcache.h anymore
take dname_external() into fs/dcache.c
let path_init() failures treated the same way as subsequent link_path_walk()
fix misuses of f_count() in ppp and netlink
ncpfs: use list_for_each_entry() for d_subdirs walk
vfs: move getname() from callers to do_mount()
gfs2_atomic_open(): skip lookups on hashed dentry
[infiniband] remove pointless assignments
gadgetfs: saner API for gadgetfs_create_file()
f_fs: saner API for ffs_sb_create_file()
jfs: don't hash direct inode
[s390] remove pointless assignment of ->f_op in vmlogrdr ->open()
ecryptfs: ->f_op is never NULL
android: ->f_op is never NULL
nouveau: __iomem misannotations
missing annotation in fs/file.c
fs: namespace: suppress 'may be used uninitialized' warnings
...
As it is, path_lookupat() and path_mounpoint() might end up leaking struct file
reference in some cases.
Spotted-by: Eric Biggers <ebiggers3@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull security subsystem updates from James Morris.
Mostly ima, selinux, smack and key handling updates.
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (65 commits)
integrity: do zero padding of the key id
KEYS: output last portion of fingerprint in /proc/keys
KEYS: strip 'id:' from ca_keyid
KEYS: use swapped SKID for performing partial matching
KEYS: Restore partial ID matching functionality for asymmetric keys
X.509: If available, use the raw subjKeyId to form the key description
KEYS: handle error code encoded in pointer
selinux: normalize audit log formatting
selinux: cleanup error reporting in selinux_nlmsg_perm()
KEYS: Check hex2bin()'s return when generating an asymmetric key ID
ima: detect violations for mmaped files
ima: fix race condition on ima_rdwr_violation_check and process_measurement
ima: added ima_policy_flag variable
ima: return an error code from ima_add_boot_aggregate()
ima: provide 'ima_appraise=log' kernel option
ima: move keyring initialization to ima_init()
PKCS#7: Handle PKCS#7 messages that contain no X.509 certs
PKCS#7: Better handling of unsupported crypto
KEYS: Overhaul key identification when searching for asymmetric keys
KEYS: Implement binary asymmetric key ID handling
...
Now that d_invalidate can no longer fail, stop returning a useless
return code. For the few callers that checked the return code update
remove the handling of d_invalidate failure.
Reviewed-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
With the introduction of mount namespaces and bind mounts it became
possible to access files and directories that on some paths are mount
points but are not mount points on other paths. It is very confusing
when rm -rf somedir returns -EBUSY simply because somedir is mounted
somewhere else. With the addition of user namespaces allowing
unprivileged mounts this condition has gone from annoying to allowing
a DOS attack on other users in the system.
The possibility for mischief is removed by updating the vfs to support
rename, unlink and rmdir on a dentry that is a mountpoint and by
lazily unmounting mountpoints on deleted dentries.
In particular this change allows rename, unlink and rmdir system calls
on a dentry without a mountpoint in the current mount namespace to
succeed, and it allows rename, unlink, and rmdir performed on a
distributed filesystem to update the vfs cache even if when there is a
mount in some namespace on the original dentry.
There are two common patterns of maintaining mounts: Mounts on trusted
paths with the parent directory of the mount point and all ancestory
directories up to / owned by root and modifiable only by root
(i.e. /media/xxx, /dev, /dev/pts, /proc, /sys, /sys/fs/cgroup/{cpu,
cpuacct, ...}, /usr, /usr/local). Mounts on unprivileged directories
maintained by fusermount.
In the case of mounts in trusted directories owned by root and
modifiable only by root the current parent directory permissions are
sufficient to ensure a mount point on a trusted path is not removed
or renamed by anyone other than root, even if there is a context
where the there are no mount points to prevent this.
In the case of mounts in directories owned by less privileged users
races with users modifying the path of a mount point are already a
danger. fusermount already uses a combination of chdir,
/proc/<pid>/fd/NNN, and UMOUNT_NOFOLLOW to prevent these races. The
removable of global rename, unlink, and rmdir protection really adds
nothing new to consider only a widening of the attack window, and
fusermount is already safe against unprivileged users modifying the
directory simultaneously.
In principle for perfect userspace programs returning -EBUSY for
unlink, rmdir, and rename of dentires that have mounts in the local
namespace is actually unnecessary. Unfortunately not all userspace
programs are perfect so retaining -EBUSY for unlink, rmdir and rename
of dentries that have mounts in the current mount namespace plays an
important role of maintaining consistency with historical behavior and
making imperfect userspace applications hard to exploit.
v2: Remove spurious old_dentry.
v3: Optimized shrink_submounts_and_drop
Removed unsued afs label
v4: Simplified the changes to check_submounts_and_drop
Do not rename check_submounts_and_drop shrink_submounts_and_drop
Document what why we need atomicity in check_submounts_and_drop
Rely on the parent inode mutex to make d_revalidate and d_invalidate
an atomic unit.
v5: Refcount the mountpoint to detach in case of simultaneous
renames.
Reviewed-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
In preparation for allowing mountpoints to be renamed and unlinked
in remote filesystems and in other mount namespaces test if on a dentry
there is a mount in the local mount namespace before allowing it to
be renamed or unlinked.
The primary motivation here are old versions of fusermount unmount
which is not safe if the a path can be renamed or unlinked while it is
verifying the mount is safe to unmount. More recent versions are simpler
and safer by simply using UMOUNT_NOFOLLOW when unmounting a mount
in a directory owned by an arbitrary user.
Miklos Szeredi <miklos@szeredi.hu> reports this is approach is good
enough to remove concerns about new kernels mixed with old versions
of fusermount.
A secondary motivation for restrictions here is that it removing empty
directories that have non-empty mount points on them appears to
violate the rule that rmdir can not remove empty directories. As
Linus Torvalds pointed out this is useful for programs (like git) that
test if a directory is empty with rmdir.
Therefore this patch arranges to enforce the existing mount point
semantics for local mount namespace.
v2: Rewrote the test to be a drop in replacement for d_mountpoint
v3: Use bool instead of int as the return type of is_local_mountpoint
Reviewed-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit d6bb3e9075 ("vfs: simplify and shrink stack frame of
link_path_walk()") introduced build problems with GCC versions older
than 4.6 due to the initialisation of a member of an anonymous union in
struct qstr without enclosing braces.
This hits GCC bug 10676 [1] (which was fixed in GCC 4.6 by [2]), and
causes the following build error:
fs/namei.c: In function 'link_path_walk':
fs/namei.c:1778: error: unknown field 'hash_len' specified in initializer
This is worked around by adding explicit braces.
[1] https://gcc.gnu.org/bugzilla/show_bug.cgi?id=10676
[2] https://gcc.gnu.org/viewcvs/gcc?view=revision&revision=159206
Fixes: d6bb3e9075 (vfs: simplify and shrink stack frame of link_path_walk())
Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: linux-fsdevel@vger.kernel.org
Cc: linux-metag@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 9226b5b440 ("vfs: avoid non-forwarding large load after small
store in path lookup") made link_path_walk() always access the
"hash_len" field as a single 64-bit entity, in order to avoid mixed size
accesses to the members.
However, what I didn't notice was that that effectively means that the
whole "struct qstr this" is now basically redundant. We already
explicitly track the "const char *name", and if we just use "u64
hash_len" instead of "long len", there is nothing else left of the
"struct qstr".
We do end up wanting the "struct qstr" if we have a filesystem with a
"d_hash()" function, but that's a rare case, and we might as well then
just squirrell away the name and hash_len at that point.
End result: fewer live variables in the loop, a smaller stack frame, and
better code generation. And we don't need to pass in pointers variables
to helper functions any more, because the return value contains all the
relevant information. So this removes more lines than it adds, and the
source code is clearer too.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull vfs fixes from Al Viro:
"double iput() on failure exit in lustre, racy removal of spliced
dentries from ->s_anon in __d_materialise_dentry() plus a bunch of
assorted RCU pathwalk fixes"
The RCU pathwalk fixes end up fixing a couple of cases where we
incorrectly dropped out of RCU walking, due to incorrect initialization
and testing of the sequence locks in some corner cases. Since dropping
out of RCU walk mode forces the slow locked accesses, those corner cases
slowed down quite dramatically.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
be careful with nd->inode in path_init() and follow_dotdot_rcu()
don't bugger nd->seq on set_root_rcu() from follow_dotdot_rcu()
fix bogus read_seqretry() checks introduced in b37199e
move the call of __d_drop(anon) into __d_materialise_unique(dentry, anon)
[fix] lustre: d_make_root() does iput() on dentry allocation failure
The performance regression that Josef Bacik reported in the pathname
lookup (see commit 99d263d4c5 "vfs: fix bad hashing of dentries") made
me look at performance stability of the dcache code, just to verify that
the problem was actually fixed. That turned up a few other problems in
this area.
There are a few cases where we exit RCU lookup mode and go to the slow
serializing case when we shouldn't, Al has fixed those and they'll come
in with the next VFS pull.
But my performance verification also shows that link_path_walk() turns
out to have a very unfortunate 32-bit store of the length and hash of
the name we look up, followed by a 64-bit read of the combined hash_len
field. That screws up the processor store to load forwarding, causing
an unnecessary hickup in this critical routine.
It's caused by the ugly calling convention for the "hash_name()"
function, and easily fixed by just making hash_name() fill in the whole
'struct qstr' rather than passing it a pointer to just the hash value.
With that, the profile for this function looks much smoother.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
in the former we simply check if dentry is still valid after picking
its ->d_inode; in the latter we fetch ->d_inode in the same places
where we fetch dentry and its ->d_seq, under the same checks.
Cc: stable@vger.kernel.org # 2.6.38+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
return the value instead, and have path_init() do the assignment. Broken by
"vfs: Fix absolute RCU path walk failures due to uninitialized seq number",
which was Cc-stable with 2.6.38+ as destination. This one should go where
it went.
To avoid dummy value returned in case when root is already set (it would do
no harm, actually, since the only caller that doesn't ignore the return value
is guaranteed to have nd->root *not* set, but it's more obvious that way),
lift the check into callers. And do the same to set_root(), to keep them
in sync.
Cc: stable@vger.kernel.org # 2.6.38+
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Josef Bacik found a performance regression between 3.2 and 3.10 and
narrowed it down to commit bfcfaa77bd ("vfs: use 'unsigned long'
accesses for dcache name comparison and hashing"). He reports:
"The test case is essentially
for (i = 0; i < 1000000; i++)
mkdir("a$i");
On xfs on a fio card this goes at about 20k dir/sec with 3.2, and 12k
dir/sec with 3.10. This is because we spend waaaaay more time in
__d_lookup on 3.10 than in 3.2.
The new hashing function for strings is suboptimal for <
sizeof(unsigned long) string names (and hell even > sizeof(unsigned
long) string names that I've tested). I broke out the old hashing
function and the new one into a userspace helper to get real numbers
and this is what I'm getting:
Old hash table had 1000000 entries, 0 dupes, 0 max dupes
New hash table had 12628 entries, 987372 dupes, 900 max dupes
We had 11400 buckets with a p50 of 30 dupes, p90 of 240 dupes, p99 of 567 dupes for the new hash
My test does the hash, and then does the d_hash into a integer pointer
array the same size as the dentry hash table on my system, and then
just increments the value at the address we got to see how many
entries we overlap with.
As you can see the old hash function ended up with all 1 million
entries in their own bucket, whereas the new one they are only
distributed among ~12.5k buckets, which is why we're using so much
more CPU in __d_lookup".
The reason for this hash regression is two-fold:
- On 64-bit architectures the down-mixing of the original 64-bit
word-at-a-time hash into the final 32-bit hash value is very
simplistic and suboptimal, and just adds the two 32-bit parts
together.
In particular, because there is no bit shuffling and the mixing
boundary is also a byte boundary, similar character patterns in the
low and high word easily end up just canceling each other out.
- the old byte-at-a-time hash mixed each byte into the final hash as it
hashed the path component name, resulting in the low bits of the hash
generally being a good source of hash data. That is not true for the
word-at-a-time case, and the hash data is distributed among all the
bits.
The fix is the same in both cases: do a better job of mixing the bits up
and using as much of the hash data as possible. We already have the
"hash_32|64()" functions to do that.
Reported-by: Josef Bacik <jbacik@fb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chris Mason <clm@fb.com>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Empty files and missing xattrs do not guarantee that a file was
just created. This patch passes FILE_CREATED flag to IMA to
reliably identify new files.
Signed-off-by: Dmitry Kasatkin <d.kasatkin@samsung.com>
Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: <stable@vger.kernel.org> 3.14+
Looks like the directory loop check is actually done in renameat?
Whatever, leave this out rather than trying to keep it up to date with
the code.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
In REF-walk mode, ->d_manage can return -EISDIR to indicate
that the dentry is not really a mount trap (or even a mount point)
and that any mounts or any DCACHE_NEED_AUTOMOUNT flag should be
ignored.
RCU-walk mode doesn't currently support this, so if there is a dentry
with DCACHE_NEED_AUTOMOUNT set but which shouldn't be a mount-trap,
lookup_fast() will always drop in REF-walk mode.
With this patch, an -EISDIR from ->d_manage will always cause mounts
and automounts to be ignored, both in REF-walk and RCU-walk.
Bug-fixed-by: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Ian Kent <raven@themaw.net>
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Christoph Hellwig suggests:
1) make vfs_rename call ->rename2 if it exists instead of ->rename
2) switch all filesystems that you're adding NOREPLACE support for to
use ->rename2
3) see how many ->rename instances we'll have left after a few
iterations of 2.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Currently umount on symlink blocks following umount:
/vz is separate mount
# ls /vz/ -al | grep test
drwxr-xr-x. 2 root root 4096 Jul 19 01:14 testdir
lrwxrwxrwx. 1 root root 11 Jul 19 01:16 testlink -> /vz/testdir
# umount -l /vz/testlink
umount: /vz/testlink: not mounted (expected)
# lsof /vz
# umount /vz
umount: /vz: device is busy. (unexpected)
In this case mountpoint_last() gets an extra refcount on path->mnt
Signed-off-by: Vasily Averin <vvs@openvz.org>
Acked-by: Ian Kent <raven@themaw.net>
Acked-by: Jeff Layton <jlayton@primarydata.com>
Cc: stable@vger.kernel.org
Signed-off-by: Christoph Hellwig <hch@lst.de>
The kernel has no concept of capabilities with respect to inodes; inodes
exist independently of namespaces. For example, inode_capable(inode,
CAP_LINUX_IMMUTABLE) would be nonsense.
This patch changes inode_capable to check for uid and gid mappings and
renames it to capable_wrt_inode_uidgid, which should make it more
obvious what it does.
Fixes CVE-2014-4014.
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: Serge Hallyn <serge.hallyn@ubuntu.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: stable@vger.kernel.org
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
in non-lazy walk we need to be careful about dentry switching from
negative to positive - both ->d_flags and ->d_inode are updated,
and in some places we might see only one store. The cases where
dentry has been obtained by dcache lookup with ->i_mutex held on
parent are safe - ->d_lock and ->i_mutex provide all the barriers
we need. However, there are several places where we run into
trouble:
* do_last() fetches ->d_inode, then checks ->d_flags and
assumes that inode won't be NULL unless d_is_negative() is true.
Race with e.g. creat() - we might have fetched the old value of
->d_inode (still NULL) and new value of ->d_flags (already not
DCACHE_MISS_TYPE). Lin Ming has observed and reported the resulting
oops.
* a bunch of places checks ->d_inode for being non-NULL,
then checks ->d_flags for "is it a symlink". Race with symlink(2)
in case if our CPU sees ->d_inode update first - we see non-NULL
there, but ->d_flags still contains DCACHE_MISS_TYPE instead of
DCACHE_SYMLINK_TYPE. Result: false negative on "should we follow
link here?", with subsequent unpleasantness.
Cc: stable@vger.kernel.org # 3.13 and 3.14 need that one
Reported-and-tested-by: Lin Ming <minggr@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull vfs updates from Al Viro:
"The first vfs pile, with deep apologies for being very late in this
window.
Assorted cleanups and fixes, plus a large preparatory part of iov_iter
work. There's a lot more of that, but it'll probably go into the next
merge window - it *does* shape up nicely, removes a lot of
boilerplate, gets rid of locking inconsistencie between aio_write and
splice_write and I hope to get Kent's direct-io rewrite merged into
the same queue, but some of the stuff after this point is having
(mostly trivial) conflicts with the things already merged into
mainline and with some I want more testing.
This one passes LTP and xfstests without regressions, in addition to
usual beating. BTW, readahead02 in ltp syscalls testsuite has started
giving failures since "mm/readahead.c: fix readahead failure for
memoryless NUMA nodes and limit readahead pages" - might be a false
positive, might be a real regression..."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (63 commits)
missing bits of "splice: fix racy pipe->buffers uses"
cifs: fix the race in cifs_writev()
ceph_sync_{,direct_}write: fix an oops on ceph_osdc_new_request() failure
kill generic_file_buffered_write()
ocfs2_file_aio_write(): switch to generic_perform_write()
ceph_aio_write(): switch to generic_perform_write()
xfs_file_buffered_aio_write(): switch to generic_perform_write()
export generic_perform_write(), start getting rid of generic_file_buffer_write()
generic_file_direct_write(): get rid of ppos argument
btrfs_file_aio_write(): get rid of ppos
kill the 5th argument of generic_file_buffered_write()
kill the 4th argument of __generic_file_aio_write()
lustre: don't open-code kernel_recvmsg()
ocfs2: don't open-code kernel_recvmsg()
drbd: don't open-code kernel_recvmsg()
constify blk_rq_map_user_iov() and friends
lustre: switch to kernel_sendmsg()
ocfs2: don't open-code kernel_sendmsg()
take iov_iter stuff to mm/iov_iter.c
process_vm_access: tidy up a bit
...
Pull file locking updates from Jeff Layton:
"Highlights:
- maintainership change for fs/locks.c. Willy's not interested in
maintaining it these days, and is OK with Bruce and I taking it.
- fix for open vs setlease race that Al ID'ed
- cleanup and consolidation of file locking code
- eliminate unneeded BUG() call
- merge of file-private lock implementation"
* 'locks-3.15' of git://git.samba.org/jlayton/linux:
locks: make locks_mandatory_area check for file-private locks
locks: fix locks_mandatory_locked to respect file-private locks
locks: require that flock->l_pid be set to 0 for file-private locks
locks: add new fcntl cmd values for handling file private locks
locks: skip deadlock detection on FL_FILE_PVT locks
locks: pass the cmd value to fcntl_getlk/getlk64
locks: report l_pid as -1 for FL_FILE_PVT locks
locks: make /proc/locks show IS_FILE_PVT locks as type "FLPVT"
locks: rename locks_remove_flock to locks_remove_file
locks: consolidate checks for compatible filp->f_mode values in setlk handlers
locks: fix posix lock range overflow handling
locks: eliminate BUG() call when there's an unexpected lock on file close
locks: add __acquires and __releases annotations to locks_start and locks_stop
locks: remove "inline" qualifier from fl_link manipulation functions
locks: clean up comment typo
locks: close potential race between setlease and open
MAINTAINERS: update entry for fs/locks.c
If flags contain RENAME_EXCHANGE then exchange source and destination files.
There's no restriction on the type of the files; e.g. a directory can be
exchanged with a symlink.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Add flags to security_path_rename() and security_inode_rename() hooks.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
If this flag is specified and the target of the rename exists then the
rename syscall fails with EEXIST.
The VFS does the existence checking, so it is trivial to enable for most
local filesystems. This patch only enables it in ext4.
For network filesystems the VFS check is not enough as there may be a race
between a remote create and the rename, so these filesystems need to handle
this flag in their ->rename() implementations to ensure atomicity.
Andy writes about why this is useful:
"The trivial answer: to eliminate the race condition from 'mv -i'.
Another answer: there's a common pattern to atomically create a file
with contents: open a temporary file, write to it, optionally fsync
it, close it, then link(2) it to the final name, then unlink the
temporary file.
The reason to use link(2) is because it won't silently clobber the destination.
This is annoying:
- It requires an extra system call that shouldn't be necessary.
- It doesn't work on (IMO sensible) filesystems that don't support
hard links (e.g. vfat).
- It's not atomic -- there's an intermediate state where both files exist.
- It's ugly.
The new rename flag will make this totally sensible.
To be fair, on new enough kernels, you can also use O_TMPFILE and
linkat to achieve the same thing even more cleanly."
Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Add new renameat2 syscall, which is the same as renameat with an added
flags argument.
Pass flags to vfs_rename() and to i_op->rename() as well.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
There's actually very little difference between vfs_rename_dir() and
vfs_rename_other() so move both inline into vfs_rename() which still stays
reasonably readable.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Move the d_move() in vfs_rename_dir() up, similarly to how it's done in
vfs_rename_other(). The next patch will consolidate these two functions
and this is the only structural difference between them.
I'm not sure if doing the d_move() after the dput is even valid. But there
may be a logical explanation for that. But moving the d_move() before the
dput() (and the mutex_unlock()) should definitely not hurt.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
Add d_is_dir(dentry) helper which is analogous to S_ISDIR().
To avoid confusion, rename d_is_directory() to d_can_lookup().
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Reviewed-by: J. Bruce Fields <bfields@redhat.com>
As Trond pointed out, you can currently deadlock yourself by setting a
file-private lock on a file that requires mandatory locking and then
trying to do I/O on it.
Avoid this problem by plumbing some knowledge of file-private locks into
the mandatory locking code. In order to do this, we must pass down
information about the struct file that's being used to
locks_verify_locked.
Reported-by: Trond Myklebust <trond.myklebust@primarydata.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: J. Bruce Fields <bfields@redhat.com>
We can get false negative from __lookup_mnt() if an unrelated vfsmount
gets moved. In that case legitimize_mnt() is guaranteed to fail,
and we will fall back to non-RCU walk... unless we end up running
into a hard error on a filesystem object we wouldn't have reached
if not for that false negative. IOW, delaying that check until
the end of pathname resolution is wrong - we should recheck right
after we attempt to cross the mountpoint. We don't need to recheck
unless we see d_mountpoint() being true - in that case even if
we have just raced with mount/umount, we can simply go on as if
we'd come at the moment when the sucker wasn't a mountpoint; if we
run into a hard error as the result, it was a legitimate outcome.
__lookup_mnt() returning NULL is different in that respect, since
it might've happened due to operation on completely unrelated
mountpoint.
Cc: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Our write() system call has always been atomic in the sense that you get
the expected thread-safe contiguous write, but we haven't actually
guaranteed that concurrent writes are serialized wrt f_pos accesses, so
threads (or processes) that share a file descriptor and use "write()"
concurrently would quite likely overwrite each others data.
This violates POSIX.1-2008/SUSv4 Section XSI 2.9.7 that says:
"2.9.7 Thread Interactions with Regular File Operations
All of the following functions shall be atomic with respect to each
other in the effects specified in POSIX.1-2008 when they operate on
regular files or symbolic links: [...]"
and one of the effects is the file position update.
This unprotected file position behavior is not new behavior, and nobody
has ever cared. Until now. Yongzhi Pan reported unexpected behavior to
Michael Kerrisk that was due to this.
This resolves the issue with a f_pos-specific lock that is taken by
read/write/lseek on file descriptors that may be shared across threads
or processes.
Reported-by: Yongzhi Pan <panyongzhi@gmail.com>
Reported-by: Michael Kerrisk <mtk.manpages@gmail.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This changes 'do_execve()' to get the executable name as a 'struct
filename', and to free it when it is done. This is what the normal
users want, and it simplifies and streamlines their error handling.
The controlled lifetime of the executable name also fixes a
use-after-free problem with the trace_sched_process_exec tracepoint: the
lifetime of the passed-in string for kernel users was not at all
obvious, and the user-mode helper code used UMH_WAIT_EXEC to serialize
the pathname allocation lifetime with the execve() having finished,
which in turn meant that the trace point that happened after
mm_release() of the old process VM ended up using already free'd memory.
To solve the kernel string lifetime issue, this simply introduces
"getname_kernel()" that works like the normal user-space getname()
function, except with the source coming from kernel memory.
As Oleg points out, this also means that we could drop the tcomm[] array
from 'struct linux_binprm', since the pathname lifetime now covers
setup_new_exec(). That would be a separate cleanup.
Reported-by: Igor Zhbanov <i.zhbanov@samsung.com>
Tested-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Recent changes to retry on ESTALE in linkat
(commit 442e31ca5a)
introduced a mountpoint reference leak and a small memory
leak in case a filesystem link operation returns ESTALE
which is pretty normal for distributed filesystems like
lustre, nfs and so on.
Free old_path in such a case.
[AV: there was another missing path_put() nearby - on the previous
goto retry]
Signed-off-by: Oleg Drokin: <green@linuxhacker.ru>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Leaving getname() exported when putname() isn't is a bad idea.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Factor out the code to get an ACL either from the inode or disk from
check_acl, so that it can be used elsewhere later on.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
When explicitly hashing the end of a string with the word-at-a-time
interface, we have to be careful which end of the word we pick up.
On big-endian CPUs, the upper-bits will contain the data we're after, so
ensure we generate our masks accordingly (and avoid hashing whatever
random junk may have been sitting after the string).
This patch adds a new dcache helper, bytemask_from_count, which creates
a mask appropriate for the CPU endianness.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Failure to grab reference to parent dentry should go through the
same cleanup as nd->seq mismatch. As it is, we might end up with
caller thinking it needs to path_put() nd->root, with obvious
nasty results once we'd hit that bug enough times to drive the
refcount of root dentry all the way to zero...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull audit updates from Eric Paris:
"Nothing amazing. Formatting, small bug fixes, couple of fixes where
we didn't get records due to some old VFS changes, and a change to how
we collect execve info..."
Fixed conflict in fs/exec.c as per Eric and linux-next.
* git://git.infradead.org/users/eparis/audit: (28 commits)
audit: fix type of sessionid in audit_set_loginuid()
audit: call audit_bprm() only once to add AUDIT_EXECVE information
audit: move audit_aux_data_execve contents into audit_context union
audit: remove unused envc member of audit_aux_data_execve
audit: Kill the unused struct audit_aux_data_capset
audit: do not reject all AUDIT_INODE filter types
audit: suppress stock memalloc failure warnings since already managed
audit: log the audit_names record type
audit: add child record before the create to handle case where create fails
audit: use given values in tty_audit enable api
audit: use nlmsg_len() to get message payload length
audit: use memset instead of trying to initialize field by field
audit: fix info leak in AUDIT_GET requests
audit: update AUDIT_INODE filter rule to comparator function
audit: audit feature to set loginuid immutable
audit: audit feature to only allow unsetting the loginuid
audit: allow unsetting the loginuid (with priv)
audit: remove CONFIG_AUDIT_LOGINUID_IMMUTABLE
audit: loginuid functions coding style
selinux: apply selinux checks on new audit message types
...
Pull vfs updates from Al Viro:
"All kinds of stuff this time around; some more notable parts:
- RCU'd vfsmounts handling
- new primitives for coredump handling
- files_lock is gone
- Bruce's delegations handling series
- exportfs fixes
plus misc stuff all over the place"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (101 commits)
ecryptfs: ->f_op is never NULL
locks: break delegations on any attribute modification
locks: break delegations on link
locks: break delegations on rename
locks: helper functions for delegation breaking
locks: break delegations on unlink
namei: minor vfs_unlink cleanup
locks: implement delegations
locks: introduce new FL_DELEG lock flag
vfs: take i_mutex on renamed file
vfs: rename I_MUTEX_QUOTA now that it's not used for quotas
vfs: don't use PARENT/CHILD lock classes for non-directories
vfs: pull ext4's double-i_mutex-locking into common code
exportfs: fix quadratic behavior in filehandle lookup
exportfs: better variable name
exportfs: move most of reconnect_path to helper function
exportfs: eliminate unused "noprogress" counter
exportfs: stop retrying once we race with rename/remove
exportfs: clear DISCONNECTED on all parents sooner
exportfs: more detailed comment for path_reconnect
...
Cc: David Howells <dhowells@redhat.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We'll need the same logic for rename and link.
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We need to break delegations on any operation that changes the set of
links pointing to an inode. Start with unlink.
Such operations also hold the i_mutex on a parent directory. Breaking a
delegation may require waiting for a timeout (by default 90 seconds) in
the case of a unresponsive NFS client. To avoid blocking all directory
operations, we therefore drop locks before waiting for the delegation.
The logic then looks like:
acquire locks
...
test for delegation; if found:
take reference on inode
release locks
wait for delegation break
drop reference on inode
retry
It is possible this could never terminate. (Even if we take precautions
to prevent another delegation being acquired on the same inode, we could
get a different inode on each retry.) But this seems very unlikely.
The initial test for a delegation happens after the lock on the target
inode is acquired, but the directory inode may have been acquired
further up the call stack. We therefore add a "struct inode **"
argument to any intervening functions, which we use to pass the inode
back up to the caller in the case it needs a delegation synchronously
broken.
Cc: David Howells <dhowells@redhat.com>
Cc: Tyler Hicks <tyhicks@canonical.com>
Cc: Dustin Kirkland <dustin.kirkland@gazzang.com>
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We'll be using dentry->d_inode in one more place.
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
A read delegation is used by NFSv4 as a guarantee that a client can
perform local read opens without informing the server.
The open operation takes the last component of the pathname as an
argument, thus is also a lookup operation, and giving the client the
above guarantee means informing the client before we allow anything that
would change the set of names pointing to the inode.
Therefore, we need to break delegations on rename, link, and unlink.
We also need to prevent new delegations from being acquired while one of
these operations is in progress.
We could add some completely new locking for that purpose, but it's
simpler to use the i_mutex, since that's already taken by all the
operations we care about.
The single exception is rename. So, modify rename to take the i_mutex
on the file that is being renamed.
Also fix up lockdep and Documentation/filesystems/directory-locking to
reflect the change.
Acked-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The DCACHE_NEED_LOOKUP case referred to here was removed with
39e3c9553f "vfs: remove
DCACHE_NEED_LOOKUP".
There are only four real_lookup() callers and all of them pass in an
unhashed dentry just returned from d_alloc.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Put a type field into struct dentry::d_flags to indicate if the dentry is one
of the following types that relate particularly to pathwalk:
Miss (negative dentry)
Directory
"Automount" directory (defective - no i_op->lookup())
Symlink
Other (regular, socket, fifo, device)
The type field is set to one of the first five types on a dentry by calls to
__d_instantiate() and d_obtain_alias() from information in the inode (if one is
given).
The type is cleared by dentry_unlink_inode() when it reconstitutes an existing
dentry as a negative dentry.
Accessors provided are:
d_set_type(dentry, type)
d_is_directory(dentry)
d_is_autodir(dentry)
d_is_symlink(dentry)
d_is_file(dentry)
d_is_negative(dentry)
d_is_positive(dentry)
A bunch of checks in pathname resolution switched to those.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* RCU-delayed freeing of vfsmounts
* vfsmount_lock replaced with a seqlock (mount_lock)
* sequence number from mount_lock is stored in nameidata->m_seq and
used when we exit RCU mode
* new vfsmount flag - MNT_SYNC_UMOUNT. Set by umount_tree() when its
caller knows that vfsmount will have no surviving references.
* synchronize_rcu() done between unlocking namespace_sem in namespace_unlock()
and doing pending mntput().
* new helper: legitimize_mnt(mnt, seq). Checks the mount_lock sequence
number against seq, then grabs reference to mnt. Then it rechecks mount_lock
again to close the race and either returns success or drops the reference it
has acquired. The subtle point is that in case of MNT_SYNC_UMOUNT we can
simply decrement the refcount and sod off - aforementioned synchronize_rcu()
makes sure that final mntput() won't come until we leave RCU mode. We need
that, since we don't want to end up with some lazy pathwalk racing with
umount() and stealing the final mntput() from it - caller of umount() may
expect it to return only once the fs is shut down and we don't want to break
that. In other cases (i.e. with MNT_SYNC_UMOUNT absent) we have to do
full-blown mntput() in case of mount_lock sequence number mismatch happening
just as we'd grabbed the reference, but in those cases we won't be stealing
the final mntput() from anything that would care.
* mntput_no_expire() doesn't lock anything on the fast path now. Incidentally,
SMP and UP cases are handled the same way - no ifdefs there.
* normal pathname resolution does *not* do any writes to mount_lock. It does,
of course, bump the refcounts of vfsmount and dentry in the very end, but that's
it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Historically, when a syscall that creates a dentry fails, you get an audit
record that looks something like this (when trying to create a file named
"new" in "/tmp/tmp.SxiLnCcv63"):
type=PATH msg=audit(1366128956.279:965): item=0 name="/tmp/tmp.SxiLnCcv63/new" inode=2138308 dev=fd:02 mode=040700 ouid=0 ogid=0 rdev=00:00 obj=staff_u:object_r:user_tmp_t:s15:c0.c1023
This record makes no sense since it's associating the inode information for
"/tmp/tmp.SxiLnCcv63" with the path "/tmp/tmp.SxiLnCcv63/new". The recent
patch I posted to fix the audit_inode call in do_last fixes this, by making it
look more like this:
type=PATH msg=audit(1366128765.989:13875): item=0 name="/tmp/tmp.DJ1O8V3e4f/" inode=141 dev=fd:02 mode=040700 ouid=0 ogid=0 rdev=00:00 obj=staff_u:object_r:user_tmp_t:s15:c0.c1023
While this is more correct, if the creation of the file fails, then we
have no record of the filename that the user tried to create.
This patch adds a call to audit_inode_child to may_create. This creates
an AUDIT_TYPE_CHILD_CREATE record that will sit in place until the
create succeeds. When and if the create does succeed, then this record
will be updated with the correct inode info from the create.
This fixes what was broken in commit bfcec708.
Commit 79f6530c should also be backported to stable v3.7+.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
Instead of passing the direction as argument (and checking it on every
step through the hash chain), just have separate __lookup_mnt() and
__lookup_mnt_last(). And use the standard iterators...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add @path parameter to fix kernel-doc warning.
Also fix a spello/typo.
Warning(fs/namei.c:2304): No description found for parameter 'path'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
If O_CREAT|O_EXCL are passed to open, then we know that either
- the file is successfully created, or
- the operation fails in some way.
So previously we set FILE_CREATED before calling ->atomic_open() so the
filesystem doesn't have to. This, however, led to bugs in the
implementation that went unnoticed when the filesystem didn't check for
existence, yet returned success. To prevent this kind of bug, require
filesystems to always explicitly set FILE_CREATED on O_CREAT|O_EXCL and
verify this in the VFS.
Also added a couple more verifications for the result of atomic_open():
- Warn if filesystem set FILE_CREATED despite the lack of O_CREAT.
- Warn if filesystem set FILE_CREATED but gave a negative dentry.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
For a long time no filesystem has been using vfs_follow_link, and as seen
by recent filesystem submissions any new use is accidental as well.
Remove vfs_follow_link, document the replacement in
Documentation/filesystems/porting and also rename __vfs_follow_link
to match its only caller better.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull vfs pile 3 (of many) from Al Viro:
"Waiman's conversion of d_path() and bits related to it,
kern_path_mountpoint(), several cleanups and fixes (exportfs
one is -stable fodder, IMO).
There definitely will be more... ;-/"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
split read_seqretry_or_unlock(), convert d_walk() to resulting primitives
dcache: Translating dentry into pathname without taking rename_lock
autofs4 - fix device ioctl mount lookup
introduce kern_path_mountpoint()
rename user_path_umountat() to user_path_mountpoint_at()
take unlazy_walk() into umount_lookup_last()
Kill indirect include of file.h from eventfd.h, use fdget() in cgroup.c
prune_super(): sb->s_op is never NULL
exportfs: don't assume that ->iterate() won't feed us too long entries
afs: get rid of redundant ->d_name.len checks
When I moved the RCU walk termination into unlazy_walk(), I didn't copy
quite all of it: for the successful RCU termination we properly add the
necessary reference counts to our temporary copy of the root path, but
for the failure case we need to make sure that any temporary root path
information is cleared out (since it does _not_ have the proper
reference counts from the RCU lookup).
We could clean up this mess by just always dropping the temporary root
information, but Al points out that that would mean that a single lookup
through symlinks could see multiple different root entries if it races
with another thread doing chroot. Not that I think we should really
care (we had that before too, back before we had a copy of the root path
in the nameidata).
Al says he has a cunning plan. In the meantime, this is the minimal fix
for the problem, even if it's not all that pretty.
Reported-by: Mace Moneta <moneta.mace@gmail.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This is the fix that the last two commits indirectly led up to - making
sure that we don't call dput() in a bad context on the dentries we've
looked up in RCU mode after the sequence count validation fails.
This basically expands d_rcu_to_refcount() into the callers, and then
fixes the callers to delay the dput() in the failure case until _after_
we've dropped all locks and are no longer in an RCU-locked region.
The case of 'complete_walk()' was trivial, since its failure case did
the unlock_rcu_walk() directly after the call to d_rcu_to_refcount(),
and as such that is just a pure expansion of the function with a trivial
movement of the resulting dput() to after 'unlock_rcu_walk()'.
In contrast, the unlazy_walk() case was much more complicated, because
not only does convert two different dentries from RCU to be reference
counted, but it used to not call unlock_rcu_walk() at all, and instead
just returned an error and let the caller clean everything up in
"terminate_walk()".
Happily, one of the dentries in question (called "parent" inside
unlazy_walk()) is the dentry of "nd->path", which terminate_walk() wants
a refcount to anyway for the non-RCU case.
So what the new and improved unlazy_walk() does is to first turn that
dentry into a refcounted one, and once that is set up, the error cases
can continue to use the terminate_walk() helper for cleanup, but for the
non-RCU case. Which makes it possible to drop out of RCU mode if we
actually hit the sequence number failure case.
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This simplifies the RCU to refcounting code in particular.
I was originally intending to leave this for later, but walking through
all the dput() logic (see previous commit), I realized that the dput()
"might_sleep()" check was misleadingly weak. And I removed it as
misleading, both for performance profiling and for debugging.
However, the might_sleep() debugging case is actually true: the final
dput() can indeed sleep, if the inode of the dentry that you are
releasing ends up sleeping at iput time (see dentry_iput()). So the
problem with the might_sleep() in dput() wasn't that it wasn't true, it
was that it wasn't actually testing and triggering on the interesting
case.
In particular, just about *any* dput() can indeed sleep, if you happen
to race with another thread deleting the file in question, and you then
lose the race to the be the last dput() for that file. But because it's
a very rare race, the debugging code would never trigger it in practice.
Why is this problematic? The new d_rcu_to_refcount() (see commit
15570086b590: "vfs: reimplement d_rcu_to_refcount() using
lockref_get_or_lock()") does a dput() for the failure case, and it does
it under the RCU lock. So potentially sleeping really is a bug.
But there's no way I'm going to fix this with the previous complicated
"lockref_get_or_lock()" interface. And rather than revert to the old
and crufty nested dentry locking code (which did get this right by
delaying the reference count updates until they were verified to be
safe), let's make forward progress.
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull vfs pile 1 from Al Viro:
"Unfortunately, this merge window it'll have a be a lot of small piles -
my fault, actually, for not keeping #for-next in anything that would
resemble a sane shape ;-/
This pile: assorted fixes (the first 3 are -stable fodder, IMO) and
cleanups + %pd/%pD formats (dentry/file pathname, up to 4 last
components) + several long-standing patches from various folks.
There definitely will be a lot more (starting with Miklos'
check_submount_and_drop() series)"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (26 commits)
direct-io: Handle O_(D)SYNC AIO
direct-io: Implement generic deferred AIO completions
add formats for dentry/file pathnames
kvm eventfd: switch to fdget
powerpc kvm: use fdget
switch fchmod() to fdget
switch epoll_ctl() to fdget
switch copy_module_from_fd() to fdget
git simplify nilfs check for busy subtree
ibmasmfs: don't bother passing superblock when not needed
don't pass superblock to hypfs_{mkdir,create*}
don't pass superblock to hypfs_diag_create_files
don't pass superblock to hypfs_vm_create_files()
oprofile: get rid of pointless forward declarations of struct super_block
oprofilefs_create_...() do not need superblock argument
oprofilefs_mkdir() doesn't need superblock argument
don't bother with passing superblock to oprofile_create_stats_files()
oprofile: don't bother with passing superblock to ->create_files()
don't bother passing sb to oprofile_create_files()
coh901318: don't open-code simple_read_from_buffer()
...
Christopher reported a regression where he was unable to unmount a NFS
filesystem where the root had gone stale. The problem is that
d_revalidate handles the root of the filesystem differently from other
dentries, but d_weak_revalidate does not. We could simply fix this by
making d_weak_revalidate return success on IS_ROOT dentries, but there
are cases where we do want to revalidate the root of the fs.
A umount is really a special case. We generally aren't interested in
anything but the dentry and vfsmount that's attached at that point. If
the inode turns out to be stale we just don't care since the intent is
to stop using it anyway.
Try to handle this situation better by treating umount as a special
case in the lookup code. Have it resolve the parent using normal
means, and then do a lookup of the final dentry without revalidating
it. In most cases, the final lookup will come out of the dcache, but
the case where there's a trailing symlink or !LAST_NORM entry on the
end complicates things a bit.
Cc: Neil Brown <neilb@suse.de>
Reported-by: Christopher T Vogan <cvogan@us.ibm.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This moves __d_rcu_to_refcount() from <linux/dcache.h> into fs/namei.c
and re-implements it using the lockref infrastructure instead. It also
adds a lot of comments about what is actually going on, because turning
a dentry that was looked up using RCU into a long-lived reference
counted entry is one of the more subtle parts of the rcu walk.
We also used to be _particularly_ subtle in unlazy_walk() where we
re-validate both the dentry and its parent using the same sequence
count. We used to do it by nesting the locks and then verifying the
sequence count just once.
That was silly, because nested locking is expensive, but the sequence
count check is not. So this just re-validates the dentry and the parent
separately, avoiding the nested locking, and making the lockref lookup
possible.
Acked-by: Waiman Long <waiman.long@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This just replaces the dentry count/lock combination with the lockref
structure that contains both a count and a spinlock, and does the
mechanical conversion to use the lockref infrastructure.
There are no semantic changes here, it's purely syntactic. The
reference lockref implementation uses the spinlock exactly the same way
that the old dcache code did, and the bulk of this patch is just
expanding the internal "d_count" use in the dcache code to use
"d_lockref.count" instead.
This is purely preparation for the real change to make the reference
count updates be lockless during the 3.12 merge window.
[ As with the previous commit, this is a rewritten version of a concept
originally from Waiman, so credit goes to him, blame for any errors
goes to me.
Waiman's patch had some semantic differences for taking advantage of
the lockless update in dget_parent(), while this patch is
intentionally a pure search-and-replace change with no semantic
changes. - Linus ]
Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This reverts commit bb2314b479.
It wasn't necessarily wrong per se, but we're still busily discussing
the exact details of this all, so I'm going to revert it for now.
It's true that you can already do flink() through /proc and that flink()
isn't new. But as Brad Spengler points out, some secure environments do
not mount proc, and flink adds a new interface that can avoid path
lookup of the source for those kinds of environments.
We may re-do this (and even mark it for stable backporting back in 3.11
and possibly earlier) once the whole discussion about the interface is done.
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Brad Spengler <spender@grsecurity.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Every now and then someone proposes a new flink syscall, and this spawns
a long discussion of whether it would be a security problem. I think
that this is missing the point: flink is *already* allowed without
privilege as long as /proc is mounted -- it's called AT_SYMLINK_FOLLOW.
Now that O_TMPFILE is here, the ability to create a file with O_TMPFILE,
write it, and link it in is very convenient. The only problem is that
it requires that /proc be mounted so that you can do:
linkat(AT_FDCWD, "/proc/self/fd/<tmpfd>", dfd, path, AT_SYMLINK_NOFOLLOW)
This sucks -- it's much nicer to do:
linkat(tmpfd, "", dfd, path, AT_EMPTY_PATH)
Let's allow it.
If this turns out to be excessively scary, it we could instead require
that the inode in question be I_LINKABLE, but this seems pointless given
the /proc situation
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[suggested by Rasmus Villemoes] make O_DIRECTORY | O_RDWR part of O_TMPFILE;
that will fail on old kernels in a lot more cases than what I came up with.
And make sure O_CREAT doesn't get there...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Instances either don't look at it at all (the majority of cases) or
only want it to find the superblock (which can be had as dentry->d_sb).
A few cases that want more are actually safe with dentry->d_inode -
the only precaution needed is the check that it hadn't been replaced with
NULL by rmdir() or by overwriting rename(), which case should be simply
treated as cache miss.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
O_TMPFILE | O_CREAT => linkat() with AT_SYMLINK_FOLLOW and /proc/self/fd/<n>
as oldpath (i.e. flink()) will create a link
O_TMPFILE | O_CREAT | O_EXCL => ENOENT on attempt to link those guys
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
/proc/self/cwd with O_CREAT should fail with EISDIR. /proc/self/exe, OTOH,
should fail with ENOTDIR when opened with O_DIRECTORY.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull audit changes from Eric Paris:
"Al used to send pull requests every couple of years but he told me to
just start pushing them to you directly.
Our touching outside of core audit code is pretty straight forward. A
couple of interface changes which hit net/. A simple argument bug
calling audit functions in namei.c and the removal of some assembly
branch prediction code on ppc"
* git://git.infradead.org/users/eparis/audit: (31 commits)
audit: fix message spacing printing auid
Revert "audit: move kaudit thread start from auditd registration to kaudit init"
audit: vfs: fix audit_inode call in O_CREAT case of do_last
audit: Make testing for a valid loginuid explicit.
audit: fix event coverage of AUDIT_ANOM_LINK
audit: use spin_lock in audit_receive_msg to process tty logging
audit: do not needlessly take a lock in tty_audit_exit
audit: do not needlessly take a spinlock in copy_signal
audit: add an option to control logging of passwords with pam_tty_audit
audit: use spin_lock_irqsave/restore in audit tty code
helper for some session id stuff
audit: use a consistent audit helper to log lsm information
audit: push loginuid and sessionid processing down
audit: stop pushing loginid, uid, sessionid as arguments
audit: remove the old depricated kernel interface
audit: make validity checking generic
audit: allow checking the type of audit message in the user filter
audit: fix build break when AUDIT_DEBUG == 2
audit: remove duplicate export of audit_enabled
Audit: do not print error when LSMs disabled
...
Jiri reported a regression in auditing of open(..., O_CREAT) syscalls.
In older kernels, creating a file with open(..., O_CREAT) created
audit_name records that looked like this:
type=PATH msg=audit(1360255720.628:64): item=1 name="/abc/foo" inode=138810 dev=fd:00 mode=0100640 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:default_t:s0
type=PATH msg=audit(1360255720.628:64): item=0 name="/abc/" inode=138635 dev=fd:00 mode=040750 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:default_t:s0
...in recent kernels though, they look like this:
type=PATH msg=audit(1360255402.886:12574): item=2 name=(null) inode=264599 dev=fd:00 mode=0100640 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:default_t:s0
type=PATH msg=audit(1360255402.886:12574): item=1 name=(null) inode=264598 dev=fd:00 mode=040750 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:default_t:s0
type=PATH msg=audit(1360255402.886:12574): item=0 name="/abc/foo" inode=264598 dev=fd:00 mode=040750 ouid=0 ogid=0 rdev=00:00 obj=unconfined_u:object_r:default_t:s0
Richard bisected to determine that the problems started with commit
bfcec708, but the log messages have changed with some later
audit-related patches.
The problem is that this audit_inode call is passing in the parent of
the dentry being opened, but audit_inode is being called with the parent
flag false. This causes later audit_inode and audit_inode_child calls to
match the wrong entry in the audit_names list.
This patch simply sets the flag to properly indicate that this inode
represents the parent. With this, the audit_names entries are back to
looking like they did before.
Cc: <stable@vger.kernel.org> # v3.7+
Reported-by: Jiri Jaburek <jjaburek@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Test By: Richard Guy Briggs <rbriggs@redhat.com>
Signed-off-by: Eric Paris <eparis@redhat.com>
It's "normal" - it can happen if the file descriptor you followed was
opened with O_NOFOLLOW.
Reported-by: Dave Jones <davej@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The following set of operations on a NFS client and server will cause
server# mkdir a
client# cd a
server# mv a a.bak
client# sleep 30 # (or whatever the dir attrcache timeout is)
client# stat .
stat: cannot stat `.': Stale NFS file handle
Obviously, we should not be getting an ESTALE error back there since the
inode still exists on the server. The problem is that the lookup code
will call d_revalidate on the dentry that "." refers to, because NFS has
FS_REVAL_DOT set.
nfs_lookup_revalidate will see that the parent directory has changed and
will try to reverify the dentry by redoing a LOOKUP. That of course
fails, so the lookup code returns ESTALE.
The problem here is that d_revalidate is really a bad fit for this case.
What we really want to know at this point is whether the inode is still
good or not, but we don't really care what name it goes by or whether
the dcache is still valid.
Add a new d_op->d_weak_revalidate operation and have complete_walk call
that instead of d_revalidate. The intent there is to allow for a
"weaker" d_revalidate that just checks to see whether the inode is still
good. This is also gives us an opportunity to kill off the FS_REVAL_DOT
special casing.
[AV: changed method name, added note in porting, fixed confusion re
having it possibly called from RCU mode (it won't be)]
Cc: NeilBrown <neilb@suse.de>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
...as always, rename is the messiest of the bunch. We have to track
whether to retry or not via a separate flag since the error handling
is already quite complex.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
...so we can pass in LOOKUP_REVAL. For now, nothing does yet.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Where we can pass in LOOKUP_DIRECTORY or LOOKUP_REVAL. Any other flags
passed in here are currently ignored.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The code that relied on that flag was ripped out of btrfs quite some
time ago, and never added back. Josef indicated that he was going to
take a different approach to the problem in btrfs, and that we
could just eliminate this flag.
Cc: Josef Bacik <jbacik@fusionio.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
When path_init is called with a valid dfd, that code checks permissions
on the open directory fd and returns an error if the check fails. This
permission check is redundant, however.
Both callers of path_init immediately call link_path_walk afterward. The
first thing that link_path_walk does for pathnames that do not consist
only of slashes is to check for exec permissions at the starting point of
the path walk. And this check in path_init() is on the path taken only
when *name != '/' && *name != '\0'.
In most cases, these checks are very quick, but when the dfd is for a
file on a NFS mount with the actimeo=0, each permission check goes
out onto the wire. The result is 2 identical ACCESS calls.
Given that these codepaths are fairly "hot", I think it makes sense to
eliminate the permission check in path_init and simply assume that the
caller will eventually check the permissions before proceeding.
Reported-by: Dave Wysochanski <dwysocha@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
In commit 800179c9b8 ("This adds symlink and hardlink restrictions to
the Linux VFS"), the new link protections were enabled by default, in
the hope that no actual application would care, despite it being
technically against legacy UNIX (and documented POSIX) behavior.
However, it does turn out to break some applications. It's rare, and
it's unfortunate, but it's unacceptable to break existing systems, so
we'll have to default to legacy behavior.
In particular, it has broken the way AFD distributes files, see
http://www.dwd.de/AFD/
along with some legacy scripts.
Distributions can end up setting this at initrd time or in system
scripts: if you have security problems due to link attacks during your
early boot sequence, you have bigger problems than some kernel sysctl
setting. Do:
echo 1 > /proc/sys/fs/protected_symlinks
echo 1 > /proc/sys/fs/protected_hardlinks
to re-enable the link protections.
Alternatively, we may at some point introduce a kernel config option
that sets these kinds of "more secure but not traditional" behavioural
options automatically.
Reported-by: Nick Bowler <nbowler@elliptictech.com>
Reported-by: Holger Kiehl <Holger.Kiehl@dwd.de>
Cc: Kees Cook <keescook@chromium.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org # v3.6
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In the common case where a name is much smaller than PATH_MAX, an extra
allocation for struct filename is unnecessary. Before allocating a
separate one, try to embed the struct filename inside the buffer first. If
it turns out that that's not long enough, then fall back to allocating a
separate struct filename and redoing the copy.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Keep a pointer to the audit_names "slot" in struct filename.
Have all of the audit_inode callers pass a struct filename ponter to
audit_inode instead of a string pointer. If the aname field is already
populated, then we can skip walking the list altogether and just use it
directly.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
...and fix up the callers. For do_file_open_root, just declare a
struct filename on the stack and fill out the .name field. For
do_filp_open, make it also take a struct filename pointer, and fix up its
callers to call it appropriately.
For filp_open, add a variant that takes a struct filename pointer and turn
filp_open into a wrapper around it.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
...and make the user_path callers use that variant instead.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Currently, if we call getname() on a userland string more than once,
we'll get multiple copies of the string and multiple audit_names
records.
Add a function that will allow the audit_names code to satisfy getname
requests using info from the audit_names list, avoiding a new allocation
and audit_names records.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
getname() is intended to copy pathname strings from userspace into a
kernel buffer. The result is just a string in kernel space. It would
however be quite helpful to be able to attach some ancillary info to
the string.
For instance, we could attach some audit-related info to reduce the
amount of audit-related processing needed. When auditing is enabled,
we could also call getname() on the string more than once and not
need to recopy it from userspace.
This patchset converts the getname()/putname() interfaces to return
a struct instead of a string. For now, the struct just tracks the
string in kernel space and the original userland pointer for it.
Later, we'll add other information to the struct as it becomes
convenient.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
In order to accomodate retrying path-based syscalls, we need to add a
new "type" argument to audit_inode_child. This will tell us whether
we're looking for a child entry that represents a create or a delete.
If we find a parent, don't automatically assume that we need to create a
new entry. Instead, use the information we have to try to find an
existing entry first. Update it if one is found and create a new one if
not.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Currently, this gets set mostly by happenstance when we call into
audit_inode_child. While that might be a little more efficient, it seems
wrong. If the syscall ends up failing before audit_inode_child ever gets
called, then you'll have an audit_names record that shows the full path
but has the parent inode info attached.
Fix this by passing in a parent flag when we call audit_inode that gets
set to the value of LOOKUP_PARENT. We can then fix up the pathname for
the audit entry correctly from the get-go.
While we're at it, clean up the no-op macro for audit_inode in the
!CONFIG_AUDITSYSCALL case.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Most of the callers get called with an inode and dentry in the reverse
order. The compiler then has to reshuffle the arg registers and/or
stack in order to pass them on to audit_inode_child.
Reverse those arguments for a micro-optimization.
Reported-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
As best I can tell, whenever retval == 0, nd->path.dentry and nd->inode
are also non-NULL. Eliminate those checks and the superfluous
audit_context check.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The follow_link() function always initializes its *p argument,
or returns an error, but when building with 'gcc -s', the compiler
gets confused by the __always_inline attribute to the function
and can no longer detect where the cookie was initialized.
The solution is to always initialize the pointer from follow_link,
even in the error path. When building with -O2, this has zero impact
on generated code and adds a single instruction in the error path
for a -Os build on ARM.
Without this patch, building with gcc-4.6 through gcc-4.8 and
CONFIG_CC_OPTIMIZE_FOR_SIZE results in:
fs/namei.c: In function 'link_path_walk':
fs/namei.c:649:24: warning: 'cookie' may be used uninitialized in this function [-Wuninitialized]
fs/namei.c:1544:9: note: 'cookie' was declared here
fs/namei.c: In function 'path_lookupat':
fs/namei.c:649:24: warning: 'cookie' may be used uninitialized in this function [-Wuninitialized]
fs/namei.c:1934:10: note: 'cookie' was declared here
fs/namei.c: In function 'path_openat':
fs/namei.c:649:24: warning: 'cookie' may be used uninitialized in this function [-Wuninitialized]
fs/namei.c:2899:9: note: 'cookie' was declared here
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit "fs: add link restriction audit reporting" has added auditing of failed
attempts to follow symlinks. Unfortunately, the auditing was being done after
the struct path structure was released earlier.
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Pull vfs update from Al Viro:
- big one - consolidation of descriptor-related logics; almost all of
that is moved to fs/file.c
(BTW, I'm seriously tempted to rename the result to fd.c. As it is,
we have a situation when file_table.c is about handling of struct
file and file.c is about handling of descriptor tables; the reasons
are historical - file_table.c used to be about a static array of
struct file we used to have way back).
A lot of stray ends got cleaned up and converted to saner primitives,
disgusting mess in android/binder.c is still disgusting, but at least
doesn't poke so much in descriptor table guts anymore. A bunch of
relatively minor races got fixed in process, plus an ext4 struct file
leak.
- related thing - fget_light() partially unuglified; see fdget() in
there (and yes, it generates the code as good as we used to have).
- also related - bits of Cyrill's procfs stuff that got entangled into
that work; _not_ all of it, just the initial move to fs/proc/fd.c and
switch of fdinfo to seq_file.
- Alex's fs/coredump.c spiltoff - the same story, had been easier to
take that commit than mess with conflicts. The rest is a separate
pile, this was just a mechanical code movement.
- a few misc patches all over the place. Not all for this cycle,
there'll be more (and quite a few currently sit in akpm's tree)."
Fix up trivial conflicts in the android binder driver, and some fairly
simple conflicts due to two different changes to the sock_alloc_file()
interface ("take descriptor handling from sock_alloc_file() to callers"
vs "net: Providing protocol type via system.sockprotoname xattr of
/proc/PID/fd entries" adding a dentry name to the socket)
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (72 commits)
MAX_LFS_FILESIZE should be a loff_t
compat: fs: Generic compat_sys_sendfile implementation
fs: push rcu_barrier() from deactivate_locked_super() to filesystems
btrfs: reada_extent doesn't need kref for refcount
coredump: move core dump functionality into its own file
coredump: prevent double-free on an error path in core dumper
usb/gadget: fix misannotations
fcntl: fix misannotations
ceph: don't abuse d_delete() on failure exits
hypfs: ->d_parent is never NULL or negative
vfs: delete surplus inode NULL check
switch simple cases of fget_light to fdget
new helpers: fdget()/fdput()
switch o2hb_region_dev_write() to fget_light()
proc_map_files_readdir(): don't bother with grabbing files
make get_file() return its argument
vhost_set_vring(): turn pollstart/pollstop into bool
switch prctl_set_mm_exe_file() to fget_light()
switch xfs_find_handle() to fget_light()
switch xfs_swapext() to fget_light()
...
Pull user namespace changes from Eric Biederman:
"This is a mostly modest set of changes to enable basic user namespace
support. This allows the code to code to compile with user namespaces
enabled and removes the assumption there is only the initial user
namespace. Everything is converted except for the most complex of the
filesystems: autofs4, 9p, afs, ceph, cifs, coda, fuse, gfs2, ncpfs,
nfs, ocfs2 and xfs as those patches need a bit more review.
The strategy is to push kuid_t and kgid_t values are far down into
subsystems and filesystems as reasonable. Leaving the make_kuid and
from_kuid operations to happen at the edge of userspace, as the values
come off the disk, and as the values come in from the network.
Letting compile type incompatible compile errors (present when user
namespaces are enabled) guide me to find the issues.
The most tricky areas have been the places where we had an implicit
union of uid and gid values and were storing them in an unsigned int.
Those places were converted into explicit unions. I made certain to
handle those places with simple trivial patches.
Out of that work I discovered we have generic interfaces for storing
quota by projid. I had never heard of the project identifiers before.
Adding full user namespace support for project identifiers accounts
for most of the code size growth in my git tree.
Ultimately there will be work to relax privlige checks from
"capable(FOO)" to "ns_capable(user_ns, FOO)" where it is safe allowing
root in a user names to do those things that today we only forbid to
non-root users because it will confuse suid root applications.
While I was pushing kuid_t and kgid_t changes deep into the audit code
I made a few other cleanups. I capitalized on the fact we process
netlink messages in the context of the message sender. I removed
usage of NETLINK_CRED, and started directly using current->tty.
Some of these patches have also made it into maintainer trees, with no
problems from identical code from different trees showing up in
linux-next.
After reading through all of this code I feel like I might be able to
win a game of kernel trivial pursuit."
Fix up some fairly trivial conflicts in netfilter uid/git logging code.
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (107 commits)
userns: Convert the ufs filesystem to use kuid/kgid where appropriate
userns: Convert the udf filesystem to use kuid/kgid where appropriate
userns: Convert ubifs to use kuid/kgid
userns: Convert squashfs to use kuid/kgid where appropriate
userns: Convert reiserfs to use kuid and kgid where appropriate
userns: Convert jfs to use kuid/kgid where appropriate
userns: Convert jffs2 to use kuid and kgid where appropriate
userns: Convert hpfs to use kuid and kgid where appropriate
userns: Convert btrfs to use kuid/kgid where appropriate
userns: Convert bfs to use kuid/kgid where appropriate
userns: Convert affs to use kuid/kgid wherwe appropriate
userns: On alpha modify linux_to_osf_stat to use convert from kuids and kgids
userns: On ia64 deal with current_uid and current_gid being kuid and kgid
userns: On ppc convert current_uid from a kuid before printing.
userns: Convert s390 getting uid and gid system calls to use kuid and kgid
userns: Convert s390 hypfs to use kuid and kgid where appropriate
userns: Convert binder ipc to use kuids
userns: Teach security_path_chown to take kuids and kgids
userns: Add user namespace support to IMA
userns: Convert EVM to deal with kuids and kgids in it's hmac computation
...
get_write_access() is needed for nfsd, not binfmt_aout (the latter
has no business doing anything of that kind, of course)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Fix kernel-doc warnings in fs/namei.c:
Warning(fs/namei.c:360): No description found for parameter 'inode'
Warning(fs/namei.c:672): No description found for parameter 'nd'
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
If ->atomic_open() returns -ENOENT, we take care to return the create
error (e.g., EACCES), if any. Do the same when ->atomic_open() returns 1
and provides a negative dentry.
This fixes a regression where an unprivileged open O_CREAT fails with
ENOENT instead of EACCES, introduced with the new atomic_open code. It
is tested by the open/08.t test in the pjd posix test suite, and was
observed on top of fuse (backed by ceph-fuse).
Signed-off-by: Sage Weil <sage@inktank.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Pass the umask-ed create mode to may_o_create() instead of the original one.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Don't mask S_ISREG off the create mode before passing to ->atomic_open(). Other
methods (->create, ->mknod) also get the complete file mode and filesystems
expect it.
Reported-by: Steve <steveamigauk@yahoo.co.uk>
Reported-by: Richard W.M. Jones <rjones@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Tested-by: Richard W.M. Jones <rjones@redhat.com>
Currently, mnt_want_write() is sometimes called with i_mutex held and sometimes
without it. This isn't really a problem because mnt_want_write() is a
non-blocking operation (essentially has a trylock semantics) but when the
function starts to handle also frozen filesystems, it will get a full lock
semantics and thus proper lock ordering has to be established. So move
all mnt_want_write() calls outside of i_mutex.
One non-trivial case needing conversion is kern_path_create() /
user_path_create() which didn't include mnt_want_write() but now needs to
because it acquires i_mutex. Because there are virtual file systems which
don't bother with freeze / remount-ro protection we actually provide both
versions of the function - one which calls mnt_want_write() and one which does
not.
[AV: scratch the previous, mnt_want_write() has been moved to kern_path_create()
by now]
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The write ref to vfsmount taken in lookup_open()/atomic_open() is going to
be dropped; we take the one to stay in dentry_open(). Just grab the temporary
in caller if it looks like we are going to need it (create/truncate/writable open)
and pass (by value) "has it succeeded" flag. Instead of doing mnt_want_write()
inside, check that flag and treat "false" as "mnt_want_write() has just failed".
mnt_want_write() is cheap and the things get considerably simpler and more robust
that way - we get it and drop it in the same function, to start with, rather
than passing a "has something in the guts of really scary functions taken it"
back to caller.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
O_EXCL without O_CREAT has different semantics; it's "fail if already opened",
not "fail if already exists". commit 71574865 broke that...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Adds audit messages for unexpected link restriction violations so that
system owners will have some sort of potentially actionable information
about misbehaving processes.
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This adds symlink and hardlink restrictions to the Linux VFS.
Symlinks:
A long-standing class of security issues is the symlink-based
time-of-check-time-of-use race, most commonly seen in world-writable
directories like /tmp. The common method of exploitation of this flaw
is to cross privilege boundaries when following a given symlink (i.e. a
root process follows a symlink belonging to another user). For a likely
incomplete list of hundreds of examples across the years, please see:
http://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=/tmp
The solution is to permit symlinks to only be followed when outside
a sticky world-writable directory, or when the uid of the symlink and
follower match, or when the directory owner matches the symlink's owner.
Some pointers to the history of earlier discussion that I could find:
1996 Aug, Zygo Blaxell
http://marc.info/?l=bugtraq&m=87602167419830&w=2
1996 Oct, Andrew Tridgell
http://lkml.indiana.edu/hypermail/linux/kernel/9610.2/0086.html
1997 Dec, Albert D Cahalan
http://lkml.org/lkml/1997/12/16/4
2005 Feb, Lorenzo Hernández García-Hierro
http://lkml.indiana.edu/hypermail/linux/kernel/0502.0/1896.html
2010 May, Kees Cook
https://lkml.org/lkml/2010/5/30/144
Past objections and rebuttals could be summarized as:
- Violates POSIX.
- POSIX didn't consider this situation and it's not useful to follow
a broken specification at the cost of security.
- Might break unknown applications that use this feature.
- Applications that break because of the change are easy to spot and
fix. Applications that are vulnerable to symlink ToCToU by not having
the change aren't. Additionally, no applications have yet been found
that rely on this behavior.
- Applications should just use mkstemp() or O_CREATE|O_EXCL.
- True, but applications are not perfect, and new software is written
all the time that makes these mistakes; blocking this flaw at the
kernel is a single solution to the entire class of vulnerability.
- This should live in the core VFS.
- This should live in an LSM. (https://lkml.org/lkml/2010/5/31/135)
- This should live in an LSM.
- This should live in the core VFS. (https://lkml.org/lkml/2010/8/2/188)
Hardlinks:
On systems that have user-writable directories on the same partition
as system files, a long-standing class of security issues is the
hardlink-based time-of-check-time-of-use race, most commonly seen in
world-writable directories like /tmp. The common method of exploitation
of this flaw is to cross privilege boundaries when following a given
hardlink (i.e. a root process follows a hardlink created by another
user). Additionally, an issue exists where users can "pin" a potentially
vulnerable setuid/setgid file so that an administrator will not actually
upgrade a system fully.
The solution is to permit hardlinks to only be created when the user is
already the existing file's owner, or if they already have read/write
access to the existing file.
Many Linux users are surprised when they learn they can link to files
they have no access to, so this change appears to follow the doctrine
of "least surprise". Additionally, this change does not violate POSIX,
which states "the implementation may require that the calling process
has permission to access the existing file"[1].
This change is known to break some implementations of the "at" daemon,
though the version used by Fedora and Ubuntu has been fixed[2] for
a while. Otherwise, the change has been undisruptive while in use in
Ubuntu for the last 1.5 years.
[1] http://pubs.opengroup.org/onlinepubs/9699919799/functions/linkat.html
[2] http://anonscm.debian.org/gitweb/?p=collab-maint/at.git;a=commitdiff;h=f4114656c3a6c6f6070e315ffdf940a49eda3279
This patch is based on the patches in Openwall and grsecurity, along with
suggestions from Al Viro. I have added a sysctl to enable the protected
behavior, and documentation.
Signed-off-by: Kees Cook <keescook@chromium.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
One side effect - attempt to create a cross-device link on a read-only fs fails
with EROFS instead of EXDEV now. Makes more sense, POSIX allows, etc.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Note that applying umask can't affect their results. While
that affects errno in cases like
mknod("/no_such_directory/a", 030000)
yielding -EINVAL (due to impossible mode_t) instead of
-ENOENT (due to inexistent directory), IMO that makes a lot
more sense, POSIX allows to return either and any software
that relies on getting -ENOENT instead of -EINVAL in that
case deserves everything it gets.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Split inode_permission() into inode- and superblock-dependent parts.
This is aimed at unionmounts where the superblock from the upper layer has to
be checked rather than the superblock from the lower layer as the upper layer
may be writable, thus allowing an unwritable file from the lower layer to be
copied up and modified.
Original-author: Valerie Aurora <vaurora@redhat.com>
Signed-off-by: David Howells <dhowells@redhat.com> (Further development)
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add comments describing what the directions "up" and "down" mean and ref count
handling to the VFS mount following family of functions.
Signed-off-by: Valerie Aurora <vaurora@redhat.com> (Original author)
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add a helper that abstracts out the jump to an already parsed struct path
from ->follow_link operation from procfs. Not only does this clean up
the code by moving the two sides of this game into a single helper, but
it also prepares for making struct nameidata private to namei.c
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Currently the non-nd_set_link based versions of ->follow_link are expected
to do a path_put(&nd->path) on failure. This calling convention is unexpected,
undocumented and doesn't match what the nd_set_link-based instances do.
Move the path_put out of the only non-nd_set_link based ->follow_link
instance into the caller.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
all callers want the same thing, actually - a kinda-sorta analog of
kern_path_create(). I.e. they want parent vfsmount/dentry (with
->i_mutex held, to make sure the child dentry is still their child)
+ the child dentry.
Signed-off-by Al Viro <viro@zeniv.linux.org.uk>
Since commit 197e37d9, the banner comment on lookup_open() no longer matches
what the function returns. It used to return a struct file pointer or NULL and
now it returns an integer and is passed the struct file pointer it is to use
amongst its arguments. Update the comment to reflect this.
Also add a banner comment to atomic_open().
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
boolean "does it have to be exclusive?" flag is passed instead;
Local filesystem should just ignore it - the object is guaranteed
not to be there yet.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Just the flags; only NFS cares even about that, but there are
legitimate uses for such argument. And getting rid of that
completely would require splitting ->lookup() into a couple
of methods (at least), so let's leave that alone for now...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Just pass struct file *. Methods are happier that way...
There's no need to return struct file * from finish_open() now,
so let it return int. Next: saner prototypes for parts in
namei.c
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Change of calling conventions:
old new
NULL 1
file 0
ERR_PTR(-ve) -ve
Caller *knows* that struct file *; no need to return it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... and let finish_open() report having opened the file via that sucker.
Next step: don't modify od->filp at all.
[AV: FILE_CREATE was already used by cifs; Miklos' fix folded]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Perform open_check_o_direct() in a common place in do_last after opening the
file.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Move the lookup retry logic to the bottom of the function to make the normal
case simpler to read.
Reported-by: David Howells <dhowells@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Consistently use bool for boolean values in do_last().
Reported-by: David Howells <dhowells@redhat.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
All users of open intents have been converted to use ->atomic_{open,create}.
This patch gets rid of nd->intent.open and related infrastructure.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add a new inode operation which is called on the last component of an open.
Using this the filesystem can look up, possibly create and open the file in one
atomic operation. If it cannot perform this (e.g. the file type turned out to
be wrong) it may signal this by returning NULL instead of an open struct file
pointer.
i_op->atomic_open() is only called if the last component is negative or needs
lookup. Handling cached positive dentries here doesn't add much value: these
can be opened using f_op->open(). If the cached file turns out to be invalid,
the open can be retried, this time using ->atomic_open() with a fresh dentry.
For now leave the old way of using open intents in lookup and revalidate in
place. This will be removed once all the users are converted.
David Howells noticed that if ->atomic_open() opens the file but does not create
it, handle_truncate() will be called on it even if it is not a regular file.
Fix this by checking the file type in this case too.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Copy __lookup_hash() into lookup_open(). The next patch will insert the atomic
open call just before the real lookup.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Split out lookup + maybe create from do_last(). This is the part under i_mutex
protection.
The function is called lookup_open() and returns a filp even though the open
part is not used yet.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Make the slow lookup part of O_CREAT and non-O_CREAT opens common.
This allows atomic_open to be hooked into the slow lookup part.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Check O_CREAT on the slow lookup paths where necessary. This allows the rest to
be shared with plain open.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
no need for kludgy "set cookie to ERR_PTR(...) because we failed
before we did actual ->follow_link() and want to suppress put_link()",
no pointless check in put_link() itself.
Callers checked if follow_link() has failed anyway; might as well
break out of their loops if that happened, without bothering
to call put_link() first.
[AV: folded fixes from hch]
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
NFS optimizes away d_revalidates for last component of open. This means that
open itself can find the dentry stale.
This patch allows the filesystem to return EOPENSTALE and the VFS will retry the
lookup on just the last component if possible.
If the lookup was done using RCU mode, including the last component, then this
is not possible since the parent dentry is lost. In this case fall back to
non-RCU lookup. Currently this is not used since NFS will always leave RCU
mode.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Now the post lookup code can be shared between O_CREAT and plain opens since
they are essentially the same.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This allows this code to be shared between O_CREAT and plain opens.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This allows this code to be shared between O_CREAT and plain opens.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Check for ENOTDIR before finishing open. This allows this code to be shared
between O_CREAT and plain opens.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Use helper variable instead of path->dentry->d_inode before complete_walk().
This will allow this code to be used in RCU mode.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Allow returning from do_last() with LOOKUP_RCU still set on the "out:" and
"exit:" labels.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Split do_lookup() into two functions:
lookup_fast() - does cached lookup without i_mutex
lookup_slow() - does lookup with i_mutex
Both follow managed dentries.
The new functions are needed by atomic_open.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
lglocks and brlocks are currently generated with some complicated macros
in lglock.h. But there's no reason to not just use common utility
functions and put all the data into a common data structure.
In preparation, this patch changes the API to look more like normal
function calls with pointers, not magic macros.
The patch is rather large because I move over all users in one go to keep
it bisectable. This impacts the VFS somewhat in terms of lines changed.
But no actual behaviour change.
[akpm@linux-foundation.org: checkpatch fixes]
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This changes the interfaces in <asm/word-at-a-time.h> to be a bit more
complicated, but a lot more generic.
In particular, it allows us to really do the operations efficiently on
both little-endian and big-endian machines, pretty much regardless of
machine details. For example, if you can rely on a fast population
count instruction on your architecture, this will allow you to make your
optimized <asm/word-at-a-time.h> file with that.
NOTE! The "generic" version in include/asm-generic/word-at-a-time.h is
not truly generic, it actually only works on big-endian. Why? Because
on little-endian the generic algorithms are wasteful, since you can
inevitably do better. The x86 implementation is an example of that.
(The only truly non-generic part of the asm-generic implementation is
the "find_zero()" function, and you could make a little-endian version
of it. And if the Kbuild infrastructure allowed us to pick a particular
header file, that would be lovely)
The <asm/word-at-a-time.h> functions are as follows:
- WORD_AT_A_TIME_CONSTANTS: specific constants that the algorithm
uses.
- has_zero(): take a word, and determine if it has a zero byte in it.
It gets the word, the pointer to the constant pool, and a pointer to
an intermediate "data" field it can set.
This is the "quick-and-dirty" zero tester: it's what is run inside
the hot loops.
- "prep_zero_mask()": take the word, the data that has_zero() produced,
and the constant pool, and generate an *exact* mask of which byte had
the first zero. This is run directly *outside* the loop, and allows
the "has_zero()" function to answer the "is there a zero byte"
question without necessarily getting exactly *which* byte is the
first one to contain a zero.
If you do multiple byte lookups concurrently (eg "hash_name()", which
looks for both NUL and '/' bytes), after you've done the prep_zero_mask()
phase, the result of those can be or'ed together to get the "either
or" case.
- The result from "prep_zero_mask()" can then be fed into "find_zero()"
(to find the byte offset of the first byte that was zero) or into
"zero_bytemask()" (to find the bytemask of the bytes preceding the
zero byte).
The existence of zero_bytemask() is optional, and is not necessary
for the normal string routines. But dentry name hashing needs it, so
if you enable DENTRY_WORD_AT_A_TIME you need to expose it.
This changes the generic strncpy_from_user() function and the dentry
hashing functions to use these modified word-at-a-time interfaces. This
gets us back to the optimized state of the x86 strncpy that we lost in
the previous commit when moving over to the generic version.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull sparc changes from David S. Miller:
"This has the generic strncpy_from_user() implementation architectures
can now use, which we've been developing on linux-arch over the past
few days.
For good measure I ran both a 32-bit and a 64-bit glibc testsuite run,
and the latter of which pointed out an adjustment I needed to make to
sparc's user_addr_max() definition. Linus, you were right, STACK_TOP
was not the right thing to use, even on sparc itself :-)
From Sam Ravnborg, we have a conversion of sparc32 over to the common
alloc_thread_info_node(), since the aspect which originally blocked
our doing so (sun4c) has been removed."
Fix up trivial arch/sparc/Kconfig and lib/Makefile conflicts.
* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc:
sparc: Fix user_addr_max() definition.
lib: Sparc's strncpy_from_user is generic enough, move under lib/
kernel: Move REPEAT_BYTE definition into linux/kernel.h
sparc: Increase portability of strncpy_from_user() implementation.
sparc: Optimize strncpy_from_user() zero byte search.
sparc: Add full proper error handling to strncpy_from_user().
sparc32: use the common implementation of alloc_thread_info_node()
Pull user namespace enhancements from Eric Biederman:
"This is a course correction for the user namespace, so that we can
reach an inexpensive, maintainable, and reasonably complete
implementation.
Highlights:
- Config guards make it impossible to enable the user namespace and
code that has not been converted to be user namespace safe.
- Use of the new kuid_t type ensures the if you somehow get past the
config guards the kernel will encounter type errors if you enable
user namespaces and attempt to compile in code whose permission
checks have not been updated to be user namespace safe.
- All uids from child user namespaces are mapped into the initial
user namespace before they are processed. Removing the need to add
an additional check to see if the user namespace of the compared
uids remains the same.
- With the user namespaces compiled out the performance is as good or
better than it is today.
- For most operations absolutely nothing changes performance or
operationally with the user namespace enabled.
- The worst case performance I could come up with was timing 1
billion cache cold stat operations with the user namespace code
enabled. This went from 156s to 164s on my laptop (or 156ns to
164ns per stat operation).
- (uid_t)-1 and (gid_t)-1 are reserved as an internal error value.
Most uid/gid setting system calls treat these value specially
anyway so attempting to use -1 as a uid would likely cause
entertaining failures in userspace.
- If setuid is called with a uid that can not be mapped setuid fails.
I have looked at sendmail, login, ssh and every other program I
could think of that would call setuid and they all check for and
handle the case where setuid fails.
- If stat or a similar system call is called from a context in which
we can not map a uid we lie and return overflowuid. The LFS
experience suggests not lying and returning an error code might be
better, but the historical precedent with uids is different and I
can not think of anything that would break by lying about a uid we
can't map.
- Capabilities are localized to the current user namespace making it
safe to give the initial user in a user namespace all capabilities.
My git tree covers all of the modifications needed to convert the core
kernel and enough changes to make a system bootable to runlevel 1."
Fix up trivial conflicts due to nearby independent changes in fs/stat.c
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (46 commits)
userns: Silence silly gcc warning.
cred: use correct cred accessor with regards to rcu read lock
userns: Convert the move_pages, and migrate_pages permission checks to use uid_eq
userns: Convert cgroup permission checks to use uid_eq
userns: Convert tmpfs to use kuid and kgid where appropriate
userns: Convert sysfs to use kgid/kuid where appropriate
userns: Convert sysctl permission checks to use kuid and kgids.
userns: Convert proc to use kuid/kgid where appropriate
userns: Convert ext4 to user kuid/kgid where appropriate
userns: Convert ext3 to use kuid/kgid where appropriate
userns: Convert ext2 to use kuid/kgid where appropriate.
userns: Convert devpts to use kuid/kgid where appropriate
userns: Convert binary formats to use kuid/kgid where appropriate
userns: Add negative depends on entries to avoid building code that is userns unsafe
userns: signal remove unnecessary map_cred_ns
userns: Teach inode_capable to understand inodes whose uids map to other namespaces.
userns: Fail exec for suid and sgid binaries with ids outside our user namespace.
userns: Convert stat to return values mapped from kuids and kgids
userns: Convert user specfied uids and gids in chown into kuids and kgid
userns: Use uid_eq gid_eq helpers when comparing kuids and kgids in the vfs
...
This branch simplifies and clarifies the dcache lookup, and allows us to
do certain nice optimizations when comparing dentries. It also cleans
up the interface to __d_lookup_rcu(), especially around passing the
inode information around.
* dentry-cleanups:
vfs: make it possible to access the dentry hash/len as one 64-bit entry
vfs: move dentry name length comparison from dentry_cmp() into callers
vfs: do the careful dentry name access for all dentry_cmp cases
vfs: remove unnecessary d_unhashed() check from __d_lookup_rcu
vfs: clean up __d_lookup_rcu() and dentry_cmp() interfaces
This teaches vfs_fstat() to use the appropriate f[get|put]_light
functions, allowing it to avoid some unnecessary locking for the common
case.
More noticeably, it also cleans up and simplifies the "getname_flags()"
function, which now relies on the architecture strncpy_from_user() doing
all the user access checks properly, instead of hacking around the fact
that on x86 it didn't use to do it right (see commit 92ae03f2ef99: "x86:
merge 32/64-bit versions of 'strncpy_from_user()' and speed it up").
* vfs-cleanups:
VFS: make vfs_fstat() use f[get|put]_light()
VFS: clean up and simplify getname_flags()
x86: make word-at-a-time strncpy_from_user clear bytes at the end
The calling conventions for __d_lookup_rcu() and dentry_cmp() are
annoying in different ways, and there is actually one single underlying
reason for both of the annoyances.
The fundamental reason is that we do the returned dentry sequence number
check inside __d_lookup_rcu() instead of doing it in the caller. This
results in two annoyances:
- __d_lookup_rcu() now not only needs to return the dentry and the
sequence number that goes along with the lookup, it also needs to
return the inode pointer that was validated by that sequence number
check.
- and because we did the sequence number check early (to validate the
name pointer and length) we also couldn't just pass the dentry itself
to dentry_cmp(), we had to pass the counted string that contained the
name.
So that sequence number decision caused two separate ugly calling
conventions.
Both of these problems would be solved if we just did the sequence
number check in the caller instead. There's only one caller, and that
caller already has to do the sequence number check for the parent
anyway, so just do that.
That allows us to stop returning the dentry->d_inode in that in-out
argument (pointer-to-pointer-to-inode), so we can make the inode
argument just a regular input inode pointer. The caller can just load
the inode from dentry->d_inode, and then do the sequence number check
after that to make sure that it's synchronized with the name we looked
up.
And it allows us to just pass in the dentry to dentry_cmp(), which is
what all the callers really wanted. Sure, dentry_cmp() has to be a bit
careful about the dentry (which is not stable during RCU lookup), but
that's actually very simple.
And now that dentry_cmp() can clearly see that the first string argument
is a dentry, we can use the direct word access for that, instead of the
careful unaligned zero-padding. The dentry name is always properly
aligned, since it is a single path component that is either embedded
into the dentry itself, or was allocated with kmalloc() (see __d_alloc).
Finally, this also uninlines the nasty slow-case for dentry comparisons:
that one *does* need to do a sequence number check, since it will call
in to the low-level filesystems, and we want to give those a stable
inode pointer and path component length/start arguments. Doing an extra
sequence check for that slow case is not a problem, though.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It turns out that there are more cases than CONFIG_DEBUG_PAGEALLOC that
can have holes in the kernel address space: it seems to happen easily
with Xen, and it looks like the AMD gart64 code will also punch holes
dynamically.
Actually hitting that case is still very unlikely, so just do the
access, and take an exception and fix it up for the very unlikely case
of it being a page-crosser with no next page.
And hey, this abstraction might even help other architectures that have
other issues with unaligned word accesses than the possible missing next
page. IOW, this could do the byte order magic too.
Peter Anvin fixed a thinko in the shifting for the exception case.
Reported-and-tested-by: Jana Saout <jana@saout.de>
Cc: Peter Anvin <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This removes a number of silly games around strncpy_from_user() in
do_getname(), and removes that helper function entirely. We instead
make getname_flags() just use strncpy_from_user() properly directly.
Removing the wrapper function simplifies things noticeably, mostly
because we no longer play the unnecessary games with segments (x86
strncpy_from_user() no longer needs the hack), but also because the
empty path handling is just much more obvious. The return value of
"strncpy_to_user()" is much more obvious than checking an odd error
return case from do_getname().
[ non-x86 architectures were notified of this change several weeks ago,
since it is possible that they have copied the old broken x86
strncpy_from_user. But nobody reacted, so .. See
http://www.spinics.net/lists/linux-arch/msg17313.html
for details ]
Cc: linux-arch@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This represents a change in strategy of how to handle user namespaces.
Instead of tagging everything explicitly with a user namespace and bulking
up all of the comparisons of uids and gids in the kernel, all uids and gids
in use will have a mapping to a flat kuid and kgid spaces respectively. This
allows much more of the existing logic to be preserved and in general
allows for faster code.
In this new and improved world we allow someone to utiliize capabilities
over an inode if the inodes owner mapps into the capabilities holders user
namespace and the user has capabilities in their user namespace. Which
is simple and efficient.
Moving the fs uid comparisons to be comparisons in a flat kuid space
follows in later patches, something that is only significant if you
are using user namespaces.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
I have a new optimized x86 "strncpy_from_user()" that will use these
same helper functions for all the same reasons the name lookup code uses
them. This is preparation for that.
This moves them into an architecture-specific header file. It's
architecture-specific for two reasons:
- some of the functions are likely to want architecture-specific
implementations. Even if the current code happens to be "generic" in
the sense that it should work on any little-endian machine, it's
likely that the "multiply by a big constant and shift" implementation
is less than optimal for an architecture that has a guaranteed fast
bit count instruction, for example.
- I expect that if architectures like sparc want to start playing
around with this, we'll need to abstract out a few more details (in
particular the actual unaligned accesses). So we're likely to have
more architecture-specific stuff if non-x86 architectures start using
this.
(and if it turns out that non-x86 architectures don't start using
this, then having it in an architecture-specific header is still the
right thing to do, of course)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Safely making device nodes in a container is solvable but simply
having the capability in a user namespace is not sufficient to make
this work.
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
64252c75a2 "vfs: remove dget() from
dentry_unhash()" changed the implementation but not the comment.
Cc: Sage Weil <sage@newdream.net>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Split __lookup_hash into two component functions:
lookup_dcache - tries cached lookup, returns whether real lookup is needed
lookup_real - calls i_op->lookup
This eliminates code duplication between d_alloc_and_lookup() and
d_inode_lookup().
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Everything arriving into if (!dentry) will have need_reval = 1.
Indeed, the only way to get there with need_reval reset to 0 would
be via
if (unlikely(d_need_lookup(dentry)))
goto unlazy;
if (unlikely(dentry->d_flags & DCACHE_OP_REVALIDATE)) {
status = d_revalidate(dentry, nd);
if (unlikely(status <= 0)) {
if (status != -ECHILD)
need_reval = 0;
goto unlazy;
...
unlazy:
/* no assignments to dentry */
if (dentry && unlikely(d_need_lookup(dentry))) {
dput(dentry);
dentry = NULL;
}
and if d_need_lookup() had already been false the first time around, it
will remain false on the second call as well.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
d_lookup() *will* fail after successful d_invalidate(), if we are
holding i_mutex all along. IOW, we don't need to jump back to
l: - we know what path will be taken there and can do that (i.e.
d_alloc_and_lookup()) directly.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Duplicate the revalidation-related parts into if (!dentry) branch.
Next step will be to pull them under i_mutex.
This and the next 8 commits are more or less a splitup of patch
by Miklos; folks, when you are working with something that convoluted,
carve your patches up into easily reviewed steps, especially when
a lot of codepaths involved are rarely hit...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The only caller of __lookup_hash() that needs the exec permission check on
parent is lookup_one_len().
All lookup_hash() callers already checked permission in LOOKUP_PARENT walk.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
__lookup_hash() calls ->lookup() if the dentry needs lookup and on success
revalidates the dentry (all under dir->i_mutex).
While this is harmless it doesn't make a lot of sense.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Doing revalidate on a dentry which has not yet been looked up makes no sense.
Move the d_need_lookup() check before d_revalidate().
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
"[PATCH 0/3] RFC - module.h usage cleanups in fs/ and lib/"
https://lkml.org/lkml/2012/2/29/589
--
Fix up files in fs/ and lib/ dirs to only use module.h if they really
need it.
These are trivial in scope vs. the work done previously. We now have
things where any few remaining cleanups can be farmed out to arch or
subsystem maintainers, and I have done so when possible. What is
remaining here represents the bits that don't clearly lie within a
single arch/subsystem boundary, like the fs dir and the lib dir.
Some duplicate includes arising from overlapping fixes from
independent subsystem maintainer submissions are also quashed.
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Merge tag 'module-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux
Pull cleanup of fs/ and lib/ users of module.h from Paul Gortmaker:
"Fix up files in fs/ and lib/ dirs to only use module.h if they really
need it.
These are trivial in scope vs the work done previously. We now have
things where any few remaining cleanups can be farmed out to arch or
subsystem maintainers, and I have done so when possible. What is
remaining here represents the bits that don't clearly lie within a
single arch/subsystem boundary, like the fs dir and the lib dir.
Some duplicate includes arising from overlapping fixes from
independent subsystem maintainer submissions are also quashed."
Fix up trivial conflicts due to clashes with other include file cleanups
(including some due to the previous bug.h cleanup pull).
* tag 'module-for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/paulg/linux:
lib: reduce the use of module.h wherever possible
fs: reduce the use of module.h wherever possible
includecheck: delete any duplicate instances of module.h
While doing the fs/namei.c cleanups, I ran sparse on it, and it pointed
out other large integers and a couple of cases of us using '0' instead
of the proper 'NULL'.
Sparse still doesn't understand some of the conditional locking going
on, but that's no excuse for not fixing up the trivial stuff.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In commit commit 1de5b41cd3 ("fs/namei.c: fix warnings on 32-bit")
Andrew said that there must be a tidier way of doing this.
This is that tidier way.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We want it to match what hash_name() is doing, which means extra
multiply by 9 in this case...
Reported-and-Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Merge first batch of patches from Andrew Morton:
"A few misc things and all the MM queue"
* emailed from Andrew Morton <akpm@linux-foundation.org>: (92 commits)
memcg: avoid THP split in task migration
thp: add HPAGE_PMD_* definitions for !CONFIG_TRANSPARENT_HUGEPAGE
memcg: clean up existing move charge code
mm/memcontrol.c: remove unnecessary 'break' in mem_cgroup_read()
mm/memcontrol.c: remove redundant BUG_ON() in mem_cgroup_usage_unregister_event()
mm/memcontrol.c: s/stealed/stolen/
memcg: fix performance of mem_cgroup_begin_update_page_stat()
memcg: remove PCG_FILE_MAPPED
memcg: use new logic for page stat accounting
memcg: remove PCG_MOVE_LOCK flag from page_cgroup
memcg: simplify move_account() check
memcg: remove EXPORT_SYMBOL(mem_cgroup_update_page_stat)
memcg: kill dead prev_priority stubs
memcg: remove PCG_CACHE page_cgroup flag
memcg: let css_get_next() rely upon rcu_read_lock()
cgroup: revert ss_id_lock to spinlock
idr: make idr_get_next() good for rcu_read_lock()
memcg: remove unnecessary thp check in page stat accounting
memcg: remove redundant returns
memcg: enum lru_list lru
...
i386 allnoconfig:
fs/namei.c: In function 'has_zero':
fs/namei.c:1617: warning: integer constant is too large for 'unsigned long' type
fs/namei.c:1617: warning: integer constant is too large for 'unsigned long' type
fs/namei.c: In function 'hash_name':
fs/namei.c:1635: warning: integer constant is too large for 'unsigned long' type
There must be a tidier way of doing this.
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull vfs pile 1 from Al Viro:
"This is _not_ all; in particular, Miklos' and Jan's stuff is not there
yet."
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (64 commits)
ext4: initialization of ext4_li_mtx needs to be done earlier
debugfs-related mode_t whack-a-mole
hfsplus: add an ioctl to bless files
hfsplus: change finder_info to u32
hfsplus: initialise userflags
qnx4: new helper - try_extent()
qnx4: get rid of qnx4_bread/qnx4_getblk
take removal of PF_FORKNOEXEC to flush_old_exec()
trim includes in inode.c
um: uml_dup_mmap() relies on ->mmap_sem being held, but activate_mm() doesn't hold it
um: embed ->stub_pages[] into mmu_context
gadgetfs: list_for_each_safe() misuse
ocfs2: fix leaks on failure exits in module_init
ecryptfs: make register_filesystem() the last potential failure exit
ntfs: forgets to unregister sysctls on register_filesystem() failure
logfs: missing cleanup on register_filesystem() failure
jfs: mising cleanup on register_filesystem() failure
make configfs_pin_fs() return root dentry on success
configfs: configfs_create_dir() has parent dentry in dentry->d_parent
configfs: sanitize configfs_create()
...
Pull kmap_atomic cleanup from Cong Wang.
It's been in -next for a long time, and it gets rid of the (no longer
used) second argument to k[un]map_atomic().
Fix up a few trivial conflicts in various drivers, and do an "evil
merge" to catch some new uses that have come in since Cong's tree.
* 'kmap_atomic' of git://github.com/congwang/linux: (59 commits)
feature-removal-schedule.txt: schedule the deprecated form of kmap_atomic() for removal
highmem: kill all __kmap_atomic() [swarren@nvidia.com: highmem: Fix ARM build break due to __kmap_atomic rename]
drbd: remove the second argument of k[un]map_atomic()
zcache: remove the second argument of k[un]map_atomic()
gma500: remove the second argument of k[un]map_atomic()
dm: remove the second argument of k[un]map_atomic()
tomoyo: remove the second argument of k[un]map_atomic()
sunrpc: remove the second argument of k[un]map_atomic()
rds: remove the second argument of k[un]map_atomic()
net: remove the second argument of k[un]map_atomic()
mm: remove the second argument of k[un]map_atomic()
lib: remove the second argument of k[un]map_atomic()
power: remove the second argument of k[un]map_atomic()
kdb: remove the second argument of k[un]map_atomic()
udf: remove the second argument of k[un]map_atomic()
ubifs: remove the second argument of k[un]map_atomic()
squashfs: remove the second argument of k[un]map_atomic()
reiserfs: remove the second argument of k[un]map_atomic()
ocfs2: remove the second argument of k[un]map_atomic()
ntfs: remove the second argument of k[un]map_atomic()
...
New field of struct super_block - ->s_max_links. Maximal allowed
value of ->i_nlink or 0; in the latter case all checks still need
to be done in ->link/->mkdir/->rename instances. Note that this
limit applies both to directoris and to non-directories.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* branch 'dcache-word-accesses':
vfs: use 'unsigned long' accesses for dcache name comparison and hashing
This does the name hashing and lookup using word-sized accesses when
that is efficient, namely on x86 (although any little-endian machine
with good unaligned accesses would do).
It does very much depend on little-endian logic, but it's a very hot
couple of functions under some real loads, and this patch improves the
performance of __d_lookup_rcu() and link_path_walk() by up to about 30%.
Giving a 10% improvement on some very pathname-heavy benchmarks.
Because we do make unaligned accesses past the filename, the
optimization is disabled when CONFIG_DEBUG_PAGEALLOC is active, and we
effectively depend on the fact that on x86 we don't really ever have the
last page of usable RAM followed immediately by any IO memory (due to
ACPI tables, BIOS buffer areas etc).
Some of the bit operations we do are a bit "subtle". It's commented,
but you do need to really think about the code. Or just consider it
black magic.
Thanks to people on G+ for some of the optimized bit tricks.
complete_walk() returns either ECHILD or ESTALE. do_last() turns this into
ECHILD unconditionally. If not in RCU mode, this error will reach userspace
which is complete nonsense.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
complete_walk() already puts nd->path, no need to do it again at cleanup time.
This would result in Oopses if triggered, apparently the codepath is not too
well exercised.
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@vger.kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Ok, this is hacky, and only works on little-endian machines with goo
unaligned handling. And even then only with CONFIG_DEBUG_PAGEALLOC
disabled, since it can access up to 7 bytes after the pathname.
But it runs like a bat out of hell.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit 5707c87f "vfs: uninline full_name_hash()" broke the modular
build, because it needs exporting now that it isn't inlined any more.
Reported-by: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The code in link_path_walk() that finds out the length and the hash of
the next path component is some of the hottest code in the kernel. And
I have a version of it that does things at the full width of the CPU
wordsize at a time, but that means that we *really* want to split it up
into a separate helper function.
So this re-organizes the code a bit and splits the hashing part into a
helper function called "hash_name()". It returns the length of the
pathname component, while at the same time computing and writing the
hash to the appropriate location.
The code generation is slightly changed by this patch, but generally for
the better - and the added abstraction actually makes the code easier to
read too. And the new interface is well suited for replacing just the
"hash_name()" function with alternative implementations.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
.. and also use it in lookup_one_len() rather than open-coding it.
There aren't any performance-critical users, so inlining it is silly.
But it wouldn't matter if it wasn't for the fact that the word-at-a-time
dentry name patches want to conditionally replace the function, and
uninlining it sets the stage for that.
So again, this is a preparatory patch that doesn't change any semantics,
and only prepares for a much cleaner and testable word-at-a-time dentry
name accessor patch.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For files only using THIS_MODULE and/or EXPORT_SYMBOL, map
them onto including export.h -- or if the file isn't even
using those, then just delete the include. Fix up any implicit
include dependencies that were being masked by module.h along
the way.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Just a code cleanup really. We don't need to make a function call just for
it to return on error. This also makes the VFS function even easier to follow
and removes a conditional on a hot path.
Signed-off-by: Eric Paris <eparis@redhat.com>
vfs_create() ignores everything outside of 16bit subset of its
mode argument; switching it to umode_t is obviously equivalent
and it's the only caller of the method
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
vfs_mkdir() gets int, but immediately drops everything that might not
fit into umode_t and that's the only caller of ->mkdir()...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Mountpoint crossing is similar to following procfs symlinks - we do
not get ->d_revalidate() called for dentry we have arrived at, with
unpleasant consequences for NFS4.
Simple way to reproduce the problem in mainline:
cat >/tmp/a.c <<'EOF'
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
main()
{
struct flock fl = {.l_type = F_RDLCK, .l_whence = SEEK_SET, .l_len = 1};
if (fcntl(0, F_SETLK, &fl))
perror("setlk");
}
EOF
cc /tmp/a.c -o /tmp/test
then on nfs4:
mount --bind file1 file2
/tmp/test < file1 # ok
/tmp/test < file2 # spews "setlk: No locks available"...
What happens is the missing call of ->d_revalidate() after mountpoint
crossing and that's where NFS4 would issue OPEN request to server.
The fix is simple - treat mountpoint crossing the same way we deal with
following procfs-style symlinks. I.e. set LOOKUP_JUMPED...
Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since the commit below which added O_PATH support to the *at() calls, the
error return for readlink/readlinkat for the empty pathname has switched
from ENOENT to EINVAL:
commit 65cfc67223
Author: Al Viro <viro@zeniv.linux.org.uk>
Date: Sun Mar 13 15:56:26 2011 -0400
readlinkat(), fchownat() and fstatat() with empty relative pathnames
This is both unexpected for userspace and makes readlink/readlinkat
inconsistant with all other interfaces; and inconsistant with our stated
return for these pathnames.
As the readlinkat call does not have a flags parameter we cannot use the
AT_EMPTY_PATH approach used in the other calls. Therefore expose whether
the original path is infact entry via a new user_path_at_empty() path
lookup function. Use this to determine whether to default to EINVAL or
ENOENT for failures.
Addresses http://bugs.launchpad.net/bugs/817187
[akpm@linux-foundation.org: remove unused getname_flags()]
Signed-off-by: Andy Whitcroft <apw@canonical.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: <stable@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
In setlease, we use i_writecount to decide whether we can give out a
read lease.
In open, we break leases before incrementing i_writecount.
There is therefore a window between the break lease and the i_writecount
increment when setlease could add a new read lease.
This would leave us with a simultaneous write open and read lease, which
shouldn't happen.
Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: J. Bruce Fields <bfields@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruen@kernel.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: J. Bruce Fields <bfields@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruen@kernel.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Acked-by: J. Bruce Fields <bfields@redhat.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andreas Gruenbacher <agruen@kernel.org>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
That flag no longer makes sense, since we don't look up automount points
as eagerly any more. Additionally, it turns out that the NO_AUTOMOUNT
handling was buggy to begin with: it would avoid automounting even for
cases where we really *needed* to do the automount handling, and could
return ENOENT for autofs entries that hadn't been instantiated yet.
With our new non-eager automount semantics, one discussion has been
about adding a AT_AUTOMOUNT flag to vfs_fstatat (and thus the
newfstatat() and fstatat64() system calls), but it's probably not worth
it: you can always force at least directory automounting by simply
adding the final '/' to the filename, which works for *all* of the stat
family system calls, old and new.
So AT_NO_AUTOMOUNT (and thus LOOKUP_NO_AUTOMOUNT) really were just a
result of our bad default behavior.
Acked-by: Ian Kent <raven@themaw.net>
Acked-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since we've now turned around and made LOOKUP_FOLLOW *not* force an
automount, we want to add the ability to force an automount event on
lookup even if we don't happen to have one of the other flags that force
it implicitly (LOOKUP_OPEN, LOOKUP_DIRECTORY, LOOKUP_PARENT..)
Most cases will never want to use this, since you'd normally want to
delay automounting as long as possible, which usually implies
LOOKUP_OPEN (when we open a file or directory, we really cannot avoid
the automount any more).
But Trond argued sufficiently forcefully that at a minimum bind mounting
a file and quotactl will want to force the automount lookup. Some other
cases (like nfs_follow_remote_path()) could use it too, although
LOOKUP_DIRECTORY would work there as well.
This commit just adds the flag and logic, no users yet, though. It also
doesn't actually touch the LOOKUP_NO_AUTOMOUNT flag that is related, and
was made irrelevant by the same change that made us not follow on
LOOKUP_FOLLOW.
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: Ian Kent <raven@themaw.net>
Cc: Jeff Layton <jlayton@redhat.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Greg KH <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We used to get the victim pinned by dentry_unhash() prior to commit
64252c75a2 ("vfs: remove dget() from dentry_unhash()") and ->rmdir()
and ->rename() instances relied on that; most of them don't care, but
ones that used d_delete() themselves do. As the result, we are getting
rmdir() oopses on NFS now.
Just grab the reference before locking the victim and drop it explicitly
after unlocking, same as vfs_rename_other() does.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Tested-by: Simon Kirby <sim@hostway.ca>
Cc: stable@kernel.org (3.0.x)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Prior to 2.6.38 automount would not trigger on either stat(2) or
lstat(2) on the automount point.
After 2.6.38, with the introduction of the ->d_automount()
infrastructure, stat(2) and others would start triggering automount
while lstat(2), etc. still would not. This is a regression and a
userspace ABI change.
Problem originally reported here:
http://thread.gmane.org/gmane.linux.kernel.autofs/6098
It appears that there was an attempt at fixing various userspace tools
to not trigger the automount. But since the stat system call is
rather common it is impossible to "fix" all userspace.
This patch reverts the original behavior, which is to not trigger on
stat(2) and other symlink following syscalls.
[ It's not really clear what the right behavior is. Apparently Solaris
does the "automount on stat, leave alone on lstat". And some programs
can get unhappy when "stat+open+fstat" ends up giving a different
result from the fstat than from the initial stat.
But the change in 2.6.38 resulted in problems for some people, so
we're going back to old behavior. Maybe we can re-visit this
discussion at some future date - Linus ]
Reported-by: Leonardo Chiquitto <leonardo.lists@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Ian Kent <raven@themaw.net>
Cc: David Howells <dhowells@redhat.com>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Al points out that the do_follow_link() helper function really is
misnamed - it's about whether we should try to follow a symlink or not,
not about actually doing the following.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
After commit 3567866bf261: "RCUify freeing acls, let check_acl() go ahead in
RCU mode if acl is cached" posix_acl_permission is being called with an
unsupported flag and the permission check fails. This patch fixes the issue.
Signed-off-by: Ari Savolainen <ari.m.savolainen@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The inode structure layout is largely random, and some of the vfs paths
really do care. The path lookup in particular is already quite D$
intensive, and profiles show that accessing the 'inode->i_op->xyz'
fields is quite costly.
We already optimized the dcache to not unnecessarily load the d_op
structure for members that are often NULL using the DCACHE_OP_xyz bits
in dentry->d_flags, and this does something very similar for the inode
ops that are used during pathname lookup.
It also re-orders the fields so that the fields accessed by 'stat' are
together at the beginning of the inode structure, and roughly in the
order accessed.
The effect of this seems to be in the 1-2% range for an empty kernel
"make -j" run (which is fairly kernel-intensive, mostly in filename
lookup), so it's visible. The numbers are fairly noisy, though, and
likely depend a lot on exact microarchitecture. So there's more tuning
to be done.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Autofs may set the DCACHE_NEED_AUTOMOUNT flag on negative dentries. These
need attention from the automounter daemon regardless of the LOOKUP_FOLLOW flag.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Commit e77819e57f ("vfs: move ACL cache lookup into generic code")
didn't take the FS_POSIX_ACL config variable into account - when that is
not set, ACL's go away, and the cache helper functions do not exist,
causing compile errors like
fs/namei.c: In function 'check_acl':
fs/namei.c:191:10: error: implicit declaration of function 'negative_cached_acl'
fs/namei.c:196:2: error: implicit declaration of function 'get_cached_acl'
fs/namei.c:196:6: warning: assignment makes pointer from integer without a cast
fs/namei.c:212:11: error: implicit declaration of function 'set_cached_acl'
Reported-by: Markus Trippelsdorf <markus@trippelsdorf.de>
Acked-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The "fsuid is the inode owner" case is not necessarily always the likely
case, but it's the case that doesn't do anything odd and that we want in
straight-line code. Make gcc not generate random "jump around for the
fun of it" code.
This just helps me read profiles. That thing is one of the hottest
parts of the whole pathname lookup.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Replace the ->check_acl method with a ->get_acl method that simply reads an
ACL from disk after having a cache miss. This means we can replace the ACL
checking boilerplate code with a single implementation in namei.c.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This moves logic for checking the cached ACL values from low-level
filesystems into generic code. The end result is a streamlined ACL
check that doesn't need to load the inode->i_op->check_acl pointer at
all for the common cached case.
The filesystems also don't need to check for a non-blocking RCU walk
case in their acl_check() functions, because that is all handled at a
VFS layer.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The flags parameter went away in
d749519b444db985e40b897f73ce1898b11f997e
Signed-off-by: Tobias Klauser <tklauser@distanz.ch>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
combination of kern_path_parent() and lookup_create(). Does *not*
expose struct nameidata to caller. Syscalls converted to that...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
pass mask instead; kill security_inode_exec_permission() since we can use
security_inode_permission() instead.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
its value depends only on inode and does not change; we might as
well store it in ->i_op->check_acl and be done with that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
capability overrides apply only to the default case; if fs has ->permission()
that does _not_ call generic_permission(), we have no business doing them.
Moreover, if it has ->permission() that does call generic_permission(), we
have no need to recheck capabilities.
Besides, the capability overrides should apply only if we got EACCES from
acl_permission_check(); any other value (-EIO, etc.) should be returned
to caller, capabilities or not capabilities.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Btrfs (and I'd venture most other fs's) stores its indexes in nice disk order
for readdir, but unfortunately in the case of anything that stats the files in
order that readdir spits back (like oh say ls) that means we still have to do
the normal lookup of the file, which means looking up our other index and then
looking up the inode. What I want is a way to create dummy dentries when we
find them in readdir so that when ls or anything else subsequently does a
stat(), we already have the location information in the dentry and can go
straight to the inode itself. The lookup stuff just assumes that if it finds a
dentry it is done, it doesn't perform a lookup. So add a DCACHE_NEED_LOOKUP
flag so that the lookup code knows it still needs to run i_op->lookup() on the
parent to get the inode for the dentry. I have tested this with btrfs and I
went from something that looks like this
http://people.redhat.com/jwhiter/ls-noreada.png
To this
http://people.redhat.com/jwhiter/ls-good.png
Thats a savings of 1300 seconds, or 22 minutes. That is a significant savings.
Thanks,
Signed-off-by: Josef Bacik <josef@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Don't update *inode in __follow_mount_rcu() until we'd verified that
there is mountpoint there. Kudos to Hugh Dickins for catching that
one in the first place and eventually figuring out the solution (and
catching a braino in the earlier version of patch).
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Make sure that child is still a child of parent before nested locking
of child->d_lock in unlazy_walk(); otherwise we are risking a violation
of locking order and deadlocks.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
[Kudos to dhowells for tracking that crap down]
If two processes attempt to cause automounting on the same mountpoint at the
same time, the vfsmount holding the mountpoint will be left with one too few
references on it, causing a BUG when the kernel tries to clean up.
The problem is that lock_mount() drops the caller's reference to the
mountpoint's vfsmount in the case where it finds something already mounted on
the mountpoint as it transits to the mounted filesystem and replaces path->mnt
with the new mountpoint vfsmount.
During a pathwalk, however, we don't take a reference on the vfsmount if it is
the same as the one in the nameidata struct, but do_add_mount() doesn't know
this.
The fix is to make sure we have a ref on the vfsmount of the mountpoint before
calling do_add_mount(). However, if lock_mount() doesn't transit, we're then
left with an extra ref on the mountpoint vfsmount which needs releasing.
We can handle that in follow_managed() by not making assumptions about what
we can and what we cannot get from lookup_mnt() as the current code does.
The callers of follow_managed() expect that reference to path->mnt will be
grabbed iff path->mnt has been changed. follow_managed() and follow_automount()
keep track of whether such reference has been grabbed and assume that it'll
happen in those and only those cases that'll have us return with changed
path->mnt. That assumption is almost correct - it breaks in case of
racing automounts and in even harder to hit race between following a mountpoint
and a couple of mount --move. The thing is, we don't need to make that
assumption at all - after the end of loop in follow_manage() we can check
if path->mnt has ended up unchanged and do mntput() if needed.
The BUG can be reproduced with the following test program:
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/wait.h>
int main(int argc, char **argv)
{
int pid, ws;
struct stat buf;
pid = fork();
stat(argv[1], &buf);
if (pid > 0) wait(&ws);
return 0;
}
and the following procedure:
(1) Mount an NFS volume that on the server has something else mounted on a
subdirectory. For instance, I can mount / from my server:
mount warthog:/ /mnt -t nfs4 -r
On the server /data has another filesystem mounted on it, so NFS will see
a change in FSID as it walks down the path, and will mark /mnt/data as
being a mountpoint. This will cause the automount code to be triggered.
!!! Do not look inside the mounted fs at this point !!!
(2) Run the above program on a file within the submount to generate two
simultaneous automount requests:
/tmp/forkstat /mnt/data/testfile
(3) Unmount the automounted submount:
umount /mnt/data
(4) Unmount the original mount:
umount /mnt
At this point the kernel should throw a BUG with something like the
following:
BUG: Dentry ffff880032e3c5c0{i=2,n=} still in use (1) [unmount of nfs4 0:12]
Note that the bug appears on the root dentry of the original mount, not the
mountpoint and not the submount because sys_umount() hasn't got to its final
mntput_no_expire() yet, but this isn't so obvious from the call trace:
[<ffffffff8117cd82>] shrink_dcache_for_umount+0x69/0x82
[<ffffffff8116160e>] generic_shutdown_super+0x37/0x15b
[<ffffffffa00fae56>] ? nfs_super_return_all_delegations+0x2e/0x1b1 [nfs]
[<ffffffff811617f3>] kill_anon_super+0x1d/0x7e
[<ffffffffa00d0be1>] nfs4_kill_super+0x60/0xb6 [nfs]
[<ffffffff81161c17>] deactivate_locked_super+0x34/0x83
[<ffffffff811629ff>] deactivate_super+0x6f/0x7b
[<ffffffff81186261>] mntput_no_expire+0x18d/0x199
[<ffffffff811862a8>] mntput+0x3b/0x44
[<ffffffff81186d87>] release_mounts+0xa2/0xbf
[<ffffffff811876af>] sys_umount+0x47a/0x4ba
[<ffffffff8109e1ca>] ? trace_hardirqs_on_caller+0x1fd/0x22f
[<ffffffff816ea86b>] system_call_fastpath+0x16/0x1b
as do_umount() is inlined. However, you can see release_mounts() in there.
Note also that it may be necessary to have multiple CPU cores to be able to
trigger this bug.
Tested-by: Jeff Layton <jlayton@redhat.com>
Tested-by: Ian Kent <raven@themaw.net>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Git bisection shows that commit e6bc45d65d causes
BUG_ONs under high I/O load:
kernel BUG at fs/inode.c:1368!
[ 2862.501007] Call Trace:
[ 2862.501007] [<ffffffff811691d8>] d_kill+0xf8/0x140
[ 2862.501007] [<ffffffff81169c19>] dput+0xc9/0x190
[ 2862.501007] [<ffffffff8115577f>] fput+0x15f/0x210
[ 2862.501007] [<ffffffff81152171>] filp_close+0x61/0x90
[ 2862.501007] [<ffffffff81152251>] sys_close+0xb1/0x110
[ 2862.501007] [<ffffffff814c14fb>] system_call_fastpath+0x16/0x1b
A reliable way to reproduce this bug is:
Login to KDE, run 'rsnapshot sync', and apt-get install openjdk-6-jdk,
and apt-get remove openjdk-6-jdk.
The buggy part of the patch is this:
struct inode *inode = NULL;
.....
- if (nd.last.name[nd.last.len])
- goto slashes;
inode = dentry->d_inode;
- if (inode)
- ihold(inode);
+ if (nd.last.name[nd.last.len] || !inode)
+ goto slashes;
+ ihold(inode)
...
if (inode)
iput(inode); /* truncate the inode here */
If nd.last.name[nd.last.len] is nonzero (and thus goto slashes branch is taken),
and dentry->d_inode is non-NULL, then this code now does an additional iput on
the inode, which is wrong.
Fix this by only setting the inode variable if nd.last.name[nd.last.len] is 0.
Reference: https://lkml.org/lkml/2011/6/15/50
Reported-by: Norbert Preining <preining@logic.at>
Reported-by: Török Edwin <edwintorok@gmail.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Török Edwin <edwintorok@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
If user space attempts to remove a non-existent file or directory, and
the file system is mounted read-only, return ENOENT instead of EROFS.
Either error code is arguably valid/correct, but ENOENT is a more
specific error message.
Reported-by: Michael Tokarev <mjt@tls.msk.ru>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The dentry_unhash push-down series missed that shink_dcache_parent needs to
be called prior to rmdir or dir rename to clear DCACHE_REFERENCED and
allow efficient dentry reclaim.
Reported-by: Dave Chinner <david@fromorbit.com>
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
... and kill a useless local variable in follow_dotdot_rcu(), while
we are at it - follow_mount_rcu(nd, path, inode) *always* assigned
value to *inode, and always it had been path->dentry->d_inode (aka
nd->path.dentry->d_inode, since it always got &nd->path as the second
argument).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6: (25 commits)
cifs: remove unnecessary dentry_unhash on rmdir/rename_dir
ocfs2: remove unnecessary dentry_unhash on rmdir/rename_dir
exofs: remove unnecessary dentry_unhash on rmdir/rename_dir
nfs: remove unnecessary dentry_unhash on rmdir/rename_dir
ext2: remove unnecessary dentry_unhash on rmdir/rename_dir
ext3: remove unnecessary dentry_unhash on rmdir/rename_dir
ext4: remove unnecessary dentry_unhash on rmdir/rename_dir
btrfs: remove unnecessary dentry_unhash in rmdir/rename_dir
ceph: remove unnecessary dentry_unhash calls
vfs: clean up vfs_rename_other
vfs: clean up vfs_rename_dir
vfs: clean up vfs_rmdir
vfs: fix vfs_rename_dir for FS_RENAME_DOES_D_MOVE filesystems
libfs: drop unneeded dentry_unhash
vfs: update dentry_unhash() comment
vfs: push dentry_unhash on rename_dir into file systems
vfs: push dentry_unhash on rmdir into file systems
vfs: remove dget() from dentry_unhash()
vfs: dentry_unhash immediately prior to rmdir
vfs: Block mmapped writes while the fs is frozen
...
vfs_rename_dir() doesn't properly account for filesystems with
FS_RENAME_DOES_D_MOVE. If new_dentry has a target inode attached, it
unhashes the new_dentry prior to the rename() iop and rehashes it after,
but doesn't account for the possibility that rename() may have swapped
{old,new}_dentry. For FS_RENAME_DOES_D_MOVE filesystems, it rehashes
new_dentry (now the old renamed-from name, which d_move() expected to go
away), such that a subsequent lookup will find it. Currently all
FS_RENAME_DOES_D_MOVE filesystems compensate for this by failing in
d_revalidate.
The bug was introduced by: commit 349457ccf2
"[PATCH] Allow file systems to manually d_move() inside of ->rename()"
Fix by not rehashing the new dentry. Rehashing used to be needed by
d_move() but isn't anymore.
Reported-by: Sage Weil <sage@newdream.net>
Signed-off-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The helper is now only called by file systems, not the VFS.
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Only a few file systems need this. Start by pushing it down into each
rename method (except gfs2 and xfs) so that it can be dealt with on a
per-fs basis.
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Only a few file systems need this. Start by pushing it down into each
fs rmdir method (except gfs2 and xfs) so it can be dealt with on a per-fs
basis.
This does not change behavior for any in-tree file systems.
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This serves no useful purpose that I can discern. All callers (rename,
rmdir) hold their own reference to the dentry.
A quick audit of all file systems showed no relevant checks on the value
of d_count in vfs_rmdir/vfs_rename_dir paths.
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This presumes that there is no reason to unhash a dentry if we fail because
it is a mountpoint or the LSM check fails, and that the LSM checks do not
depend on the dentry being unhashed.
Signed-off-by: Sage Weil <sage@newdream.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
new helper: complete_walk(). Done on successful completion
of walk, drops out of RCU mode, does d_revalidate of final
result if that hadn't been done already.
handle_reval_dot() and nameidata_drop_rcu_last() subsumed into
that one; callers converted to use of complete_walk().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This solves a serious VFS-level bug in nested_symlink (which was
rewritten from do_follow_link), and follows the order of depth tests
that existed before.
The bug triggers a BUG_ON in fs/namei.c:1381, when running racer with
symlink and rename ops.
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Acked-by: Miklos Szeredi <mszeredi@suse.cz>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's a hot function, and we're better off not mixing types in the mask
calculations. The compiler just ends up mixing 16-bit and 32-bit
operations, for no good reason.
So do everything in 'unsigned int' rather than mixing 'unsigned int'
masking with a 'umode_t' (16-bit) mode variable.
This, together with the parent commit (47a150edc2ae: "Cache user_ns in
struct cred") makes acl_permission_check() much nicer.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
During RCU walk in path_lookupat and path_openat, the rcu lookup
frequently failed if looking up an absolute path, because when root
directory was looked up, seq number was not properly set in nameidata.
We dropped out of RCU walk in nameidata_drop_rcu due to mismatch in
directory entry's seq number. We reverted to slow path walk that need
to take references.
With the following patch, I saw a 50% increase in an exim mail server
benchmark throughput on a 4-socket Nehalem-EX system.
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Cc: stable@kernel.org (v2.6.38)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When following a mount in rcu-walk mode we must check if the incoming dentry
is telling us it may need to block, even if it isn't actually a mountpoint.
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6:
deal with races in /proc/*/{syscall,stack,personality}
proc: enable writing to /proc/pid/mem
proc: make check_mem_permission() return an mm_struct on success
proc: hold cred_guard_mutex in check_mem_permission()
proc: disable mem_write after exec
mm: implement access_remote_vm
mm: factor out main logic of access_process_vm
mm: use mm_struct to resolve gate vma's in __get_user_pages
mm: arch: rename in_gate_area_no_task to in_gate_area_no_mm
mm: arch: make in_gate_area take an mm_struct instead of a task_struct
mm: arch: make get_gate_vma take an mm_struct instead of a task_struct
x86: mark associated mm when running a task in 32 bit compatibility mode
x86: add context tag to mark mm when running a task in 32-bit compatibility mode
auxv: require the target to be tracable (or yourself)
close race in /proc/*/environ
report errors in /proc/*/*map* sanely
pagemap: close races with suid execve
make sessionid permissions in /proc/*/task/* match those in /proc/*
fix leaks in path_lookupat()
Fix up trivial conflicts in fs/proc/base.c
And give it a kernel-doc comment.
[akpm@linux-foundation.org: btrfs changed in linux-next]
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Cheat for now and say all files belong to init_user_ns. Next step will be
to let superblocks belong to a user_ns, and derive inode_userns(inode)
from inode->i_sb->s_user_ns. Finally we'll introduce more flexible
arrangements.
Changelog:
Feb 15: make is_owner_or_cap take const struct inode
Feb 23: make is_owner_or_cap bool
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Serge E. Hallyn <serge.hallyn@canonical.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Daniel Lezcano <daniel.lezcano@free.fr>
Acked-by: David Howells <dhowells@redhat.com>
Cc: James Morris <jmorris@namei.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pull the handling of current->total_link_count into
__do_follow_link()
* put the common "do ->put_link() if needed and path_put() the link"
stuff into a helper (put_link(nd, link, cookie))
* rename __do_follow_link() to follow_link(), while we are at it
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The last remaining place (resolution of nested symlink) converted
to the loop of the same kind we have in path_lookupat() and
path_openat().
Note that we still *do* have a recursion in pathname resolution;
can't avoid it, really. However, it's strictly for nested symlinks
now - i.e. ones in the middle of a pathname.
link_path_walk() has lost the tail now - it always walks everything
except the last component.
do_follow_link() renamed to nested_symlink() and moved down.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Now that link_path_walk() is called without LOOKUP_PARENT
only from do_follow_link(), we can simplify the checks in
last component handling. First of all, checking if we'd
arrived to a directory is not needed - the caller will check
it anyway. And LOOKUP_FOLLOW is guaranteed to be there,
since we only get to that place with nd->depth > 0.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
new helper: walk_component(). Handles everything except symlinks;
returns negative on error, 0 on success and 1 on symlinks we decided
to follow. Drops out of RCU mode on such symlinks.
link_path_walk() and do_last() switched to using that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We don't want to allow creation of private hardlinks by different application
using the fd passed to them via SCM_RIGHTS. So limit the null relative name
usage in linkat syscall to CAP_DAC_READ_SEARCH
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
At that point we can't do almost nothing with them. They can be opened
with O_PATH, we can manipulate such descriptors with dup(), etc. and
we can see them in /proc/*/{fd,fdinfo}/*.
We can't (and won't be able to) follow /proc/*/fd/* symlinks for those;
there's simply not enough information for pathname resolution to go on
from such point - to resolve a symlink we need to know which directory
does it live in.
We will be able to do useful things with them after the next commit, though -
readlinkat() and fchownat() will be possible to use with dfd being an
O_PATH-opened symlink and empty relative pathname. Combined with
open_by_handle() it'll give us a way to do realink-by-handle and
lchown-by-handle without messing with more redundant syscalls.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
New flag for open(2) - O_PATH. Semantics:
* pathname is resolved, but the file itself is _NOT_ opened
as far as filesystem is concerned.
* almost all operations on the resulting descriptors shall
fail with -EBADF. Exceptions are:
1) operations on descriptors themselves (i.e.
close(), dup(), dup2(), dup3(), fcntl(fd, F_DUPFD),
fcntl(fd, F_DUPFD_CLOEXEC, ...), fcntl(fd, F_GETFD),
fcntl(fd, F_SETFD, ...))
2) fcntl(fd, F_GETFL), for a common non-destructive way to
check if descriptor is open
3) "dfd" arguments of ...at(2) syscalls, i.e. the starting
points of pathname resolution
* closing such descriptor does *NOT* affect dnotify or
posix locks.
* permissions are checked as usual along the way to file;
no permission checks are applied to the file itself. Of course,
giving such thing to syscall will result in permission checks (at
the moment it means checking that starting point of ....at() is
a directory and caller has exec permissions on it).
fget() and fget_light() return NULL on such descriptors; use of
fget_raw() and fget_raw_light() is needed to get them. That protects
existing code from dealing with those things.
There are two things still missing (they come in the next commits):
one is handling of symlinks (right now we refuse to open them that
way; see the next commit for semantics related to those) and another
is descriptor passing via SCM_RIGHTS datagrams.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add inode->i_nlink == 0 check in VFS. Some of the file systems
do this internally. A followup patch will remove those instance.
This is needed to ensure that with link by handle we don't allow
to create hardlink of an unlinked file. The check also prevent a race
between unlink and link
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
For name_to_handle_at(2) we'll want both ...at()-style syscall that
would be usable for non-directory descriptors (with empty relative
pathname). Introduce new flag (AT_EMPTY_PATH) to deal with that and
corresponding LOOKUP_EMPTY; teach user_path_at() and path_init() to
deal with the latter.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
new function: file_open_root(dentry, mnt, name, flags) opens the file
vfs_path_lookup would arrive to.
Note that name can be empty; in that case the usual requirement that
dentry should be a directory is lifted.
open-coded equivalents switched to it, may_open() got down exactly
one caller and became static.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
New lookup flag: LOOKUP_ROOT. nd->root is set (and held) by caller,
path_init() starts walking from that place and all pathname resolution
machinery never drops nd->root if that flag is set. That turns
vfs_path_lookup() into a special case of do_path_lookup() *and*
gets us down to 3 callers of link_path_walk(), making it finally
feasible to rip the handling of trailing symlink out of link_path_walk().
That will not only simply the living hell out of it, but make life
much simpler for unionfs merge. Trailing symlink handling will
become iterative, which is a good thing for stack footprint in
a lot of situations as well.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
That thing has devolved into rats nest of gotos; sane use of unlikely()
gets rid of that horror and gives much more readable structure:
* make a fast attempt to find a dentry; false negatives are OK.
In RCU mode if everything went fine, we are done, otherwise just drop
out of RCU. If we'd done (RCU) ->d_revalidate() and it had not refused
outright (i.e. didn't give us -ECHILD), remember its result.
* now we are not in RCU mode and hopefully have a dentry. If we
do not, lock parent, do full d_lookup() and if that has not found anything,
allocate and call ->lookup(). If we'd done that ->lookup(), remember that
dentry is good and we don't need to revalidate it.
* now we have a dentry. If it has ->d_revalidate() and we can't
skip it, call it.
* hopefully dentry is good; if not, either fail (in case of error)
or try to invalidate it. If d_invalidate() has succeeded, drop it and
retry everything as if original attempt had not found a dentry.
* now we can finish it up - deal with mountpoint crossing and
automount.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
There used to be time when ->d_revalidate() couldn't return an error.
So intents code had lookup_instantiate_filp() stash ERR_PTR(error)
in nd->intent.open.filp and had it checked after lookup_hash(), to
catch the otherwise silent failures. That had been introduced by
commit 4af4c52f34. These days
->d_revalidate() can and does propagate errors back to callers
explicitly, so this check isn't needed anymore.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We have a bunch of diverging codepaths in do_last(); some of
them converge, but the case of having to create a new file
duplicates large part of common tail of the rest and exits
separately. Massage them so that they could be merged.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Lift it to lookup_one_len() and link_path_walk() resp. into the
same place where we calculated default hash function of the same
name.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Instead of path_lookupat() doing trailing symlink resolution,
use the same scheme as on the O_CREAT side. Walk with
LOOKUP_PARENT, then (in do_last()) look the final component
up, then either open it or return error or, if it's a symlink,
give the symlink back to path_openat() to be resolved there.
The really messy complication here is RCU. We don't want to drop
out of RCU mode before the final lookup, since we don't want to
bounce parent directory ->d_count without a good reason.
Result is _not_ pretty; later in the series we'll clean it up.
For now we are roughly back where we'd been before the revert
done by Nick's series - top-level logics of path_openat() is
cleaned up, do_last() does actual opening, symlink resolution is
done uniformly.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Don't stash the struct file * used as starting point of walk in nameidata;
pass file ** to path_init() instead.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
New helper: terminate_walk(). An error has happened during pathname
resolution and we either drop nd->path or terminate RCU, depending
the mode we had been in. After that, nd is essentially empty.
Switch link_path_walk() to using that for cleanup.
Now the top-level logics in link_path_walk() is back to sanity. RCU
dependencies are in the lower-level functions.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Now we have do_follow_link() guaranteed to leave without dangling RCU
and the next step will get LOOKUP_RCU logics completely out of
link_path_walk().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
new helper: path_openat(). Does what do_filp_open() does, except
that it tries only the walk mode (RCU/normal/force revalidation)
it had been told to.
Both create and non-create branches are using path_lookupat() now.
Fixed the double audit_inode() in non-create branch.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
take calculation of open_flags by open(2) arguments into new helper
in fs/open.c, move filp_open() over there, have it and do_sys_open()
use that helper, switch exec.c callers of do_filp_open() to explicit
(and constant) struct open_flags.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
No point messing with passing shitloads of "operation mode" arguments
to do_open() one by one, especially since they are not going to change
during do_filp_open(). Collect them into a struct, fill it and pass
to do_last() by reference.
Make sure that lookup intent flags are correctly set and removed - we
want them for do_last(), but they make no sense for __do_follow_link().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
instead of ad-hackery around need_reval_dot(), do the following:
set a flag (LOOKUP_JUMPED) in the beginning of path, on absolute
symlink traversal, on ".." and on procfs-style symlinks. Clear on
normal components, leave unchanged on ".". Non-nested callers of
link_path_walk() call handle_reval_path(), which checks that flag
is set and that fs does want the final revalidate thing, then does
->d_revalidate(). In link_path_walk() all the return_reval stuff
is gone.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Actual dependency on whether we want RCU or not is in 3 small areas
(as it ought to be) and everything around those is the same in both
versions. Since each function has only one caller and those callers
are on two sides of if (flags & LOOKUP_RCU), it's easier and cleaner
to merge them and pull the checks inside.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
New helper: path_lookupat(). Basically, what do_path_lookup() boils to
modulo -ECHILD/-ESTALE handler. path_walk* family is gone; vfs_path_lookup()
is using link_path_walk() directly, do_path_lookup() and do_filp_open()
are using path_lookupat().
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
all remaining callers pass LOOKUP_PARENT to it, so
flags argument can die; renamed to kern_path_parent()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We leave it at whatever it had been pointing to after the
first link_path_walk() had failed with -ESTALE. Things
do not work well after that...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
failure exits on the no-O_CREAT side of do_filp_open() merge with
those of O_CREAT one; unfortunately, if do_path_lookup() returns
-ESTALE, we'll get out_filp:, notice that we are about to return
-ESTALE without having trying to create the sucker with LOOKUP_REVAL
and jump right into the O_CREAT side of code. And proceed to try
and create a file. Usually that'll fail with -ESTALE again, but
we can race and get that attempt of pathname resolution to succeed.
open() without O_CREAT really shouldn't end up creating files, races
or not. The real fix is to rearchitect the whole do_filp_open(),
but for now splitting the failure exits will do.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
When Al moved the nameidata_dentry_drop_rcu_maybe() call into the
do_follow_link function in commit 844a391799 ("nothing in
do_follow_link() is going to see RCU"), he mistakenly left the
BUG_ON(inode != path->dentry->d_inode);
behind. Which would otherwise be ok, but that BUG_ON() really needs to
be _after_ dropping RCU, since the dentry isn't necessarily stable
otherwise.
So complete the code movement in that commit, and move the BUG_ON() into
do_follow_link() too. This means that we need to pass in 'inode' as an
argument (just for this one use), but that's a small thing. And
eventually we may be confident enough in our path lookup that we can
just remove the BUG_ON() and the unnecessary inode argument.
Reported-and-tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In commit 31e6b01f41 ("fs: rcu-walk for path lookup") we started doing
path lookup using RCU, which then falls back to a careful non-RCU lookup
in case of problems (LOOKUP_REVAL). So do_filp_open() has this "re-do
the lookup carefully" looping case.
However, that means that we must not release the open-intent file data
if we are going to loop around and use it once more!
Fix this by moving the release of the open-intent data to the function
that allocates it (do_filp_open() itself) rather than the helper
functions that can get called multiple times (finish_open() and
do_last()). This makes the logic for the lifetime of that field much
more obvious, and avoids the possible double free.
Reported-by: J. R. Okajima <hooanon05@yahoo.co.jp>
Acked-by: Al Viro <viro@zeniv.linux.org.uk>
Cc: Nick Piggin <npiggin@kernel.dk>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a ref count problem in fs/namei.c:do_lookup().
When walking in ref-walk mode, if follow_managed() returns a fail we
need to drop dentry and possibly vfsmount. Clean up properly,
as we do in the other caller of follow_managed().
Signed-off-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Instead of splitting refcount between (per-cpu) mnt_count
and (SMP-only) mnt_longrefs, make all references contribute
to mnt_count again and keep track of how many are longterm
ones.
Accounting rules for longterm count:
* 1 for each fs_struct.root.mnt
* 1 for each fs_struct.pwd.mnt
* 1 for having non-NULL ->mnt_ns
* decrement to 0 happens only under vfsmount lock exclusive
That allows nice common case for mntput() - since we can't drop the
final reference until after mnt_longterm has reached 0 due to the rules
above, mntput() can grab vfsmount lock shared and check mnt_longterm.
If it turns out to be non-zero (which is the common case), we know
that this is not the final mntput() and can just blindly decrement
percpu mnt_count. Otherwise we grab vfsmount lock exclusive and
do usual decrement-and-check of percpu mnt_count.
For fs_struct.c we have mnt_make_longterm() and mnt_make_shortterm();
namespace.c uses the latter in places where we don't already hold
vfsmount lock exclusive and opencodes a few remaining spots where
we need to manipulate mnt_longterm.
Note that we mostly revert the code outside of fs/namespace.c back
to what we used to have; in particular, normal code doesn't need
to care about two kinds of references, etc. And we get to keep
the optimization Nick's variant had bought us...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Unexport do_add_mount() and make ->d_automount() return the vfsmount to be
added rather than calling do_add_mount() itself. follow_automount() will then
do the addition.
This slightly complicates things as ->d_automount() normally wants to add the
new vfsmount to an expiration list and start an expiration timer. The problem
with that is that the vfsmount will be deleted if it has a refcount of 1 and
the timer will not repeat if the expiration list is empty.
To this end, we require the vfsmount to be returned from d_automount() with a
refcount of (at least) 2. One of these refs will be dropped unconditionally.
In addition, follow_automount() must get a 3rd ref around the call to
do_add_mount() lest it eat a ref and return an error, leaving the mount we
have open to being expired as we would otherwise have only 1 ref on it.
d_automount() should also add the the vfsmount to the expiration list (by
calling mnt_set_expiry()) and start the expiration timer before returning, if
this mechanism is to be used. The vfsmount will be unlinked from the
expiration list by follow_automount() if do_add_mount() fails.
This patch also fixes the call to do_add_mount() for AFS to propagate the mount
flags from the parent vfsmount.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Allow d_manage() to be called from pathwalk when it is in RCU-walk mode as well
as when it is in Ref-walk mode. This permits __follow_mount_rcu() to call
d_manage() directly. d_manage() needs a parameter to indicate that it is in
RCU-walk mode as it isn't allowed to sleep if in that mode (but should return
-ECHILD instead).
autofs4_d_manage() can then be set to retain RCU-walk mode if the daemon
accesses it and otherwise request dropping back to ref-walk mode.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Remove a further kludge from __do_follow_link() as it's no longer required with
the automount code.
This reverts the non-helper-function parts of
051d381259, which breaks union mounts.
Reported-by: vaurora@redhat.com
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Remove the automount through follow_link() kludge code from pathwalk in favour
of using d_automount().
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add an AT_NO_AUTOMOUNT flag to suppress terminal automounting of automount
point directories. This can be used by fstatat() users to permit the
gathering of attributes on an automount point and also prevent
mass-automounting of a directory of automount points by ls.
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add a dentry op (d_manage) to permit a filesystem to hold a process and make it
sleep when it tries to transit away from one of that filesystem's directories
during a pathwalk. The operation is keyed off a new dentry flag
(DCACHE_MANAGE_TRANSIT).
The filesystem is allowed to be selective about which processes it holds and
which it permits to continue on or prohibits from transiting from each flagged
directory. This will allow autofs to hold up client processes whilst letting
its userspace daemon through to maintain the directory or the stuff behind it
or mounted upon it.
The ->d_manage() dentry operation:
int (*d_manage)(struct path *path, bool mounting_here);
takes a pointer to the directory about to be transited away from and a flag
indicating whether the transit is undertaken by do_add_mount() or
do_move_mount() skipping through a pile of filesystems mounted on a mountpoint.
It should return 0 if successful and to let the process continue on its way;
-EISDIR to prohibit the caller from skipping to overmounted filesystems or
automounting, and to use this directory; or some other error code to return to
the user.
->d_manage() is called with namespace_sem writelocked if mounting_here is true
and no other locks held, so it may sleep. However, if mounting_here is true,
it may not initiate or wait for a mount or unmount upon the parameter
directory, even if the act is actually performed by userspace.
Within fs/namei.c, follow_managed() is extended to check with d_manage() first
on each managed directory, before transiting away from it or attempting to
automount upon it.
follow_down() is renamed follow_down_one() and should only be used where the
filesystem deliberately intends to avoid management steps (e.g. autofs).
A new follow_down() is added that incorporates the loop done by all other
callers of follow_down() (do_add/move_mount(), autofs and NFSD; whilst AFS, NFS
and CIFS do use it, their use is removed by converting them to use
d_automount()). The new follow_down() calls d_manage() as appropriate. It
also takes an extra parameter to indicate if it is being called from mount code
(with namespace_sem writelocked) which it passes to d_manage(). follow_down()
ignores automount points so that it can be used to mount on them.
__follow_mount_rcu() is made to abort rcu-walk mode if it hits a directory with
DCACHE_MANAGE_TRANSIT set on the basis that we're probably going to have to
sleep. It would be possible to enter d_manage() in rcu-walk mode too, and have
that determine whether to abort or not itself. That would allow the autofs
daemon to continue on in rcu-walk mode.
Note that DCACHE_MANAGE_TRANSIT on a directory should be cleared when it isn't
required as every tranist from that directory will cause d_manage() to be
invoked. It can always be set again when necessary.
==========================
WHAT THIS MEANS FOR AUTOFS
==========================
Autofs currently uses the lookup() inode op and the d_revalidate() dentry op to
trigger the automounting of indirect mounts, and both of these can be called
with i_mutex held.
autofs knows that the i_mutex will be held by the caller in lookup(), and so
can drop it before invoking the daemon - but this isn't so for d_revalidate(),
since the lock is only held on _some_ of the code paths that call it. This
means that autofs can't risk dropping i_mutex from its d_revalidate() function
before it calls the daemon.
The bug could manifest itself as, for example, a process that's trying to
validate an automount dentry that gets made to wait because that dentry is
expired and needs cleaning up:
mkdir S ffffffff8014e05a 0 32580 24956
Call Trace:
[<ffffffff885371fd>] :autofs4:autofs4_wait+0x674/0x897
[<ffffffff80127f7d>] avc_has_perm+0x46/0x58
[<ffffffff8009fdcf>] autoremove_wake_function+0x0/0x2e
[<ffffffff88537be6>] :autofs4:autofs4_expire_wait+0x41/0x6b
[<ffffffff88535cfc>] :autofs4:autofs4_revalidate+0x91/0x149
[<ffffffff80036d96>] __lookup_hash+0xa0/0x12f
[<ffffffff80057a2f>] lookup_create+0x46/0x80
[<ffffffff800e6e31>] sys_mkdirat+0x56/0xe4
versus the automount daemon which wants to remove that dentry, but can't
because the normal process is holding the i_mutex lock:
automount D ffffffff8014e05a 0 32581 1 32561
Call Trace:
[<ffffffff80063c3f>] __mutex_lock_slowpath+0x60/0x9b
[<ffffffff8000ccf1>] do_path_lookup+0x2ca/0x2f1
[<ffffffff80063c89>] .text.lock.mutex+0xf/0x14
[<ffffffff800e6d55>] do_rmdir+0x77/0xde
[<ffffffff8005d229>] tracesys+0x71/0xe0
[<ffffffff8005d28d>] tracesys+0xd5/0xe0
which means that the system is deadlocked.
This patch allows autofs to hold up normal processes whilst the daemon goes
ahead and does things to the dentry tree behind the automouter point without
risking a deadlock as almost no locks are held in d_manage() and none in
d_automount().
Signed-off-by: David Howells <dhowells@redhat.com>
Was-Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add a dentry op (d_automount) to handle automounting directories rather than
abusing the follow_link() inode operation. The operation is keyed off a new
dentry flag (DCACHE_NEED_AUTOMOUNT).
This also makes it easier to add an AT_ flag to suppress terminal segment
automount during pathwalk and removes the need for the kludge code in the
pathwalk algorithm to handle directories with follow_link() semantics.
The ->d_automount() dentry operation:
struct vfsmount *(*d_automount)(struct path *mountpoint);
takes a pointer to the directory to be mounted upon, which is expected to
provide sufficient data to determine what should be mounted. If successful, it
should return the vfsmount struct it creates (which it should also have added
to the namespace using do_add_mount() or similar). If there's a collision with
another automount attempt, NULL should be returned. If the directory specified
by the parameter should be used directly rather than being mounted upon,
-EISDIR should be returned. In any other case, an error code should be
returned.
The ->d_automount() operation is called with no locks held and may sleep. At
this point the pathwalk algorithm will be in ref-walk mode.
Within fs/namei.c itself, a new pathwalk subroutine (follow_automount()) is
added to handle mountpoints. It will return -EREMOTE if the automount flag was
set, but no d_automount() op was supplied, -ELOOP if we've encountered too many
symlinks or mountpoints, -EISDIR if the walk point should be used without
mounting and 0 if successful. The path will be updated to point to the mounted
filesystem if a successful automount took place.
__follow_mount() is replaced by follow_managed() which is more generic
(especially with the patch that adds ->d_manage()). This handles transits from
directories during pathwalk, including automounting and skipping over
mountpoints (and holding processes with the next patch).
__follow_mount_rcu() will jump out of RCU-walk mode if it encounters an
automount point with nothing mounted on it.
follow_dotdot*() does not handle automounts as you don't want to trigger them
whilst following "..".
I've also extracted the mount/don't-mount logic from autofs4 and included it
here. It makes the mount go ahead anyway if someone calls open() or creat(),
tries to traverse the directory, tries to chdir/chroot/etc. into the directory,
or sticks a '/' on the end of the pathname. If they do a stat(), however,
they'll only trigger the automount if they didn't also say O_NOFOLLOW.
I've also added an inode flag (S_AUTOMOUNT) so that filesystems can mark their
inodes as automount points. This flag is automatically propagated to the
dentry as DCACHE_NEED_AUTOMOUNT by __d_instantiate(). This saves NFS and could
save AFS a private flag bit apiece, but is not strictly necessary. It would be
preferable to do the propagation in d_set_d_op(), but that doesn't normally
have access to the inode.
[AV: fixed breakage in case if __follow_mount_rcu() fails and nameidata_drop_rcu()
succeeds in RCU case of do_lookup(); we need to fall through to non-RCU case after
that, rather than just returning with ungrabbed *path]
Signed-off-by: David Howells <dhowells@redhat.com>
Was-Acked-by: Ian Kent <raven@themaw.net>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
do_lookup() has a path leading from LOOKUP_RCU case to non-RCU
crossing of mountpoints, which breaks things badly. If we
hit need_revalidate: and do nothing in there, we need to come
back into LOOKUP_RCU half of things, not to done: in non-RCU
one.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin:
kernel: fix hlist_bl again
cgroups: Fix a lockdep warning at cgroup removal
fs: namei fix ->put_link on wrong inode in do_filp_open
J. R. Okajima noticed that ->put_link is being attempted on the
wrong inode, and suggested the way to fix it. I changed it a bit
according to Al's suggestion to keep an explicit link path around.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
* 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin:
fs: fix do_last error case when need_reval_dot
nfs: add missing rcu-walk check
fs: hlist UP debug fixup
fs: fix dropping of rcu-walk from force_reval_path
fs: force_reval_path drop rcu-walk before d_invalidate
fs: small rcu-walk documentation fixes
Fixed up trivial conflicts in Documentation/filesystems/porting
When open(2) without O_DIRECTORY opens an existing dir, it should return
EISDIR. In do_last(), the variable 'error' is initialized EISDIR, but it
is changed by d_revalidate() which returns any positive to represent
'the target dir is valid.'
Should we keep and return the initialized 'error' in this case.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
As J. R. Okajima noted, force_reval_path passes in the same dentry to
d_revalidate as the one in the nameidata structure (other callers pass in a
child), so the locking breaks. This can oops with a chrooted nfs mount, for
example. Similarly there can be other problems with revalidating a dentry
which is already in nameidata of the path walk.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
d_revalidate can return in rcu-walk mode even when it returns 0. We can't just
call any old dcache function on rcu-walk dentry (the dentry is unstable, so
even through d_lock can safely be taken, the result may no longer be what we
expect -- careful re-checks would be required). So just drop rcu in this case.
(I missed this conversion when switching to the rcu-walk convention that Linus
suggested)
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
When a file is opened with O_TRUNC, the truncate processing is handled
by handle_truncate(). This function however doesn't receive any info
about the newly instantiated filp, and therefore can't pass that info
along so that the setattr can use it.
This makes NFSv4 misbehave. The client does an open and gets a valid
stateid, and then doesn't use that stateid on the subsequent truncate.
It uses the zero-stateid instead. Most servers ignore this fact and
just do the truncate anyway, but some don't like it (notably, RHEL4).
It seems more correct that since we have a fully instantiated file at
the time that handle_truncate is called, that we pass that along so
that the truncate operation can properly use it.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Fix new kernel-doc notation warnings in fs/namei.c and spell
ECHILD correctly.
Warning(fs/namei.c:218): No description found for parameter 'flags'
Warning(fs/namei.c:425): Excess function parameter 'Returns' description in 'nameidata_drop_rcu'
Warning(fs/namei.c:478): Excess function parameter 'Returns' description in 'nameidata_dentry_drop_rcu'
Warning(fs/namei.c:540): Excess function parameter 'Returns' description in 'nameidata_drop_rcu_last'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The problem that this patch aims to fix is vfsmount refcounting scalability.
We need to take a reference on the vfsmount for every successful path lookup,
which often go to the same mount point.
The fundamental difficulty is that a "simple" reference count can never be made
scalable, because any time a reference is dropped, we must check whether that
was the last reference. To do that requires communication with all other CPUs
that may have taken a reference count.
We can make refcounts more scalable in a couple of ways, involving keeping
distributed counters, and checking for the global-zero condition less
frequently.
- check the global sum once every interval (this will delay zero detection
for some interval, so it's probably a showstopper for vfsmounts).
- keep a local count and only taking the global sum when local reaches 0 (this
is difficult for vfsmounts, because we can't hold preempt off for the life of
a reference, so a counter would need to be per-thread or tied strongly to a
particular CPU which requires more locking).
- keep a local difference of increments and decrements, which allows us to sum
the total difference and hence find the refcount when summing all CPUs. Then,
keep a single integer "long" refcount for slow and long lasting references,
and only take the global sum of local counters when the long refcount is 0.
This last scheme is what I implemented here. Attached mounts and process root
and working directory references are "long" references, and everything else is
a short reference.
This allows scalable vfsmount references during path walking over mounted
subtrees and unattached (lazy umounted) mounts with processes still running
in them.
This results in one fewer atomic op in the fastpath: mntget is now just a
per-CPU inc, rather than an atomic inc; and mntput just requires a spinlock
and non-atomic decrement in the common case. However code is otherwise bigger
and heavier, so single threaded performance is basically a wash.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Require filesystems be aware of .d_revalidate being called in rcu-walk
mode (nd->flags & LOOKUP_RCU). For now do a simple push down, returning
-ECHILD from all implementations.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Reduce some branches and memory accesses in dcache lookup by adding dentry
flags to indicate common d_ops are set, rather than having to check them.
This saves a pointer memory access (dentry->d_op) in common path lookup
situations, and saves another pointer load and branch in cases where we
have d_op but not the particular operation.
Patched with:
git grep -E '[.>]([[:space:]])*d_op([[:space:]])*=' | xargs sed -e 's/\([^\t ]*\)->d_op = \(.*\);/d_set_d_op(\1, \2);/' -e 's/\([^\t ]*\)\.d_op = \(.*\);/d_set_d_op(\&\1, \2);/' -i
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Use a seqlock in the fs_struct to enable us to take an atomic copy of the
complete cwd and root paths. Use this in the RCU lookup path to avoid a
thread-shared spinlock in RCU lookup operations.
Multi-threaded apps may now perform path lookups with scalability matching
multi-process apps. Operations such as stat(2) become very scalable for
multi-threaded workload.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Perform common cases of path lookups without any stores or locking in the
ancestor dentry elements. This is called rcu-walk, as opposed to the current
algorithm which is a refcount based walk, or ref-walk.
This results in far fewer atomic operations on every path element,
significantly improving path lookup performance. It also avoids cacheline
bouncing on common dentries, significantly improving scalability.
The overall design is like this:
* LOOKUP_RCU is set in nd->flags, which distinguishes rcu-walk from ref-walk.
* Take the RCU lock for the entire path walk, starting with the acquiring
of the starting path (eg. root/cwd/fd-path). So now dentry refcounts are
not required for dentry persistence.
* synchronize_rcu is called when unregistering a filesystem, so we can
access d_ops and i_ops during rcu-walk.
* Similarly take the vfsmount lock for the entire path walk. So now mnt
refcounts are not required for persistence. Also we are free to perform mount
lookups, and to assume dentry mount points and mount roots are stable up and
down the path.
* Have a per-dentry seqlock to protect the dentry name, parent, and inode,
so we can load this tuple atomically, and also check whether any of its
members have changed.
* Dentry lookups (based on parent, candidate string tuple) recheck the parent
sequence after the child is found in case anything changed in the parent
during the path walk.
* inode is also RCU protected so we can load d_inode and use the inode for
limited things.
* i_mode, i_uid, i_gid can be tested for exec permissions during path walk.
* i_op can be loaded.
When we reach the destination dentry, we lock it, recheck lookup sequence,
and increment its refcount and mountpoint refcount. RCU and vfsmount locks
are dropped. This is termed "dropping rcu-walk". If the dentry refcount does
not match, we can not drop rcu-walk gracefully at the current point in the
lokup, so instead return -ECHILD (for want of a better errno). This signals the
path walking code to re-do the entire lookup with a ref-walk.
Aside from the final dentry, there are other situations that may be encounted
where we cannot continue rcu-walk. In that case, we drop rcu-walk (ie. take
a reference on the last good dentry) and continue with a ref-walk. Again, if
we can drop rcu-walk gracefully, we return -ECHILD and do the whole lookup
using ref-walk. But it is very important that we can continue with ref-walk
for most cases, particularly to avoid the overhead of double lookups, and to
gain the scalability advantages on common path elements (like cwd and root).
The cases where rcu-walk cannot continue are:
* NULL dentry (ie. any uncached path element)
* parent with d_inode->i_op->permission or ACLs
* dentries with d_revalidate
* Following links
In future patches, permission checks and d_revalidate become rcu-walk aware. It
may be possible eventually to make following links rcu-walk aware.
Uncached path elements will always require dropping to ref-walk mode, at the
very least because i_mutex needs to be grabbed, and objects allocated.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Make d_count non-atomic and protect it with d_lock. This allows us to ensure a
0 refcount dentry remains 0 without dcache_lock. It is also fairly natural when
we start protecting many other dentry members with d_lock.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Change d_hash so it may be called from lock-free RCU lookups. See similar
patch for d_compare for details.
For in-tree filesystems, this is just a mechanical change.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Unsetting FMODE_NONOTIFY in fsnotify_open() is too late, since fsnotify_perm()
is called before. If FMODE_NONOTIFY is set fsnotify_perm() will skip permission
checks, so a user can still disable permission checks by setting this flag
in an open() call.
This patch corrects this by unsetting the flag before fsnotify_perm is called.
Signed-off-by: Lino Sanfilippo <LinoSanfilippo@gmx.de>
Signed-off-by: Eric Paris <eparis@redhat.com>
nameidata_to_filp() drops nd->path or transfers it to opened
file. In the former case it's a Bad Idea(tm) to do mnt_drop_write()
on nd->path.mnt, since we might race with umount and vfsmount in
question might be gone already.
Fix: don't drop it, then... IOW, have nameidata_to_filp() grab nd->path
in case it transfers it to file and do path_drop() in callers. After
they are through with accessing nd->path...
Reported-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
fs: brlock vfsmount_lock
Use a brlock for the vfsmount lock. It must be taken for write whenever
modifying the mount hash or associated fields, and may be taken for read when
performing mount hash lookups.
A new lock is added for the mnt-id allocator, so it doesn't need to take
the heavy vfsmount write-lock.
The number of atomics should remain the same for fastpath rlock cases, though
code would be slightly slower due to per-cpu access. Scalability is not not be
much improved in common cases yet, due to other locks (ie. dcache_lock) getting
in the way. However path lookups crossing mountpoints should be one case where
scalability is improved (currently requiring the global lock).
The slowpath is slower due to use of brlock. On a 64 core, 64 socket, 32 node
Altix system (high latency to remote nodes), a simple umount microbenchmark
(mount --bind mnt mnt2 ; umount mnt2 loop 1000 times), before this patch it
took 6.8s, afterwards took 7.1s, about 5% slower.
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
fs: remove extra lookup in __lookup_hash
Optimize lookup for create operations, where no dentry should often be
common-case. In cases where it is not, such as unlink, the added overhead
is much smaller than the removed.
Also, move comments about __d_lookup racyness to the __d_lookup call site.
d_lookup is intuitive; __d_lookup is what needs commenting. So in that same
vein, add kerneldoc comments to __d_lookup and clean up some of the comments:
- We are interested in how the RCU lookup works here, particularly with
renames. Make that explicit, and point to the document where it is explained
in more detail.
- RCU is pretty standard now, and macros make implementations pretty mindless.
If we want to know about RCU barrier details, we look in RCU code.
- Delete some boring legacy comments because we don't care much about how the
code used to work, more about the interesting parts of how it works now. So
comments about lazy LRU may be interesting, but would better be done in the
LRU or refcount management code.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
fs: dentry allocation consolidation
There are 2 duplicate copies of code in dentry allocation in path lookup.
Consolidate them into a single function.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
fs: fix do_lookup false negative
In do_lookup, if we initially find no dentry, we take the directory i_mutex and
re-check the lookup. If we find a dentry there, then we revalidate it if
needed. However if that revalidate asks for the dentry to be invalidated, we
return -ENOENT from do_lookup. What should happen instead is an attempt to
allocate and lookup a new dentry.
This is probably not noticed because it is rare. It is only reached if a
concurrent create races in first (in which case, the dentry probably won't be
invalidated anyway), or if the racy __d_lookup has failed due to a
false-negative (which is very rare).
Fix this by removing code and have it use the normal reval path.
Signed-off-by: Nick Piggin <npiggin@kernel.dk>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Add three helpers that retrieve a refcounted copy of the root and cwd
from the supplied fs_struct.
get_fs_root()
get_fs_pwd()
get_fs_root_and_pwd()
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* 'for-linus' of git://git.infradead.org/users/eparis/notify: (132 commits)
fanotify: use both marks when possible
fsnotify: pass both the vfsmount mark and inode mark
fsnotify: walk the inode and vfsmount lists simultaneously
fsnotify: rework ignored mark flushing
fsnotify: remove global fsnotify groups lists
fsnotify: remove group->mask
fsnotify: remove the global masks
fsnotify: cleanup should_send_event
fanotify: use the mark in handler functions
audit: use the mark in handler functions
dnotify: use the mark in handler functions
inotify: use the mark in handler functions
fsnotify: send fsnotify_mark to groups in event handling functions
fsnotify: Exchange list heads instead of moving elements
fsnotify: srcu to protect read side of inode and vfsmount locks
fsnotify: use an explicit flag to indicate fsnotify_destroy_mark has been called
fsnotify: use _rcu functions for mark list traversal
fsnotify: place marks on object in order of group memory address
vfs/fsnotify: fsnotify_close can delay the final work in fput
fsnotify: store struct file not struct path
...
Fix up trivial delete/modify conflict in fs/notify/inotify/inotify.c.
SELinux needs to pass the MAY_ACCESS flag so it can handle auditting
correctly. Presently the masking of MAY_* flags is done in the VFS. In
order to allow LSMs to decide what flags they care about and what flags
they don't just pass them all and the each LSM mask off what they don't
need. This patch should contain no functional changes to either the VFS or
any LSM.
Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Stephen D. Smalley <sds@tycho.nsa.gov>
Signed-off-by: James Morris <jmorris@namei.org>
When commit be6d3e56a6 "introduce new LSM hooks
where vfsmount is available." was proposed, regarding security_path_truncate(),
only "struct file *" argument (which AppArmor wanted to use) was removed.
But length and time_attrs arguments are not used by TOMOYO nor AppArmor.
Thus, let's remove these arguments.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: James Morris <jmorris@namei.org>
fsnotify was using char * when it passed around the d_name.name string
internally but it is actually an unsigned char *. This patch switches
fsnotify to use unsigned and should silence some pointer signess warnings
which have popped out of xfs. I do not add -Wpointer-sign to the fsnotify
code as there are still issues with kstrdup and strlen which would pop
out needless warnings.
Signed-off-by: Eric Paris <eparis@redhat.com>
Commit 1f36f774b2 broke FS_REVAL_DOT semantics.
In particular, before this patch, the command
ls -l
in an NFS mounted directory would always check if the directory on the server
had changed and if so would flush and refill the pagecache for the dir.
After this patch, the same "ls -l" will repeatedly return stale date until
the cached attributes for the directory time out.
The following patch fixes this by ensuring the d_revalidate is called by
do_last when "." is being looked-up.
link_path_walk has already called d_revalidate, but in that case LOOKUP_OPEN
is not set so nfs_lookup_verify_inode chooses not to do any validation.
The following patch restores the original behaviour.
Cc: stable@kernel.org
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
update the mnt of the path when it is not equal to the new one.
Signed-off-by: Huang Shijie <shijie8@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
1) i_flags simply doesn't work for mount/unlink race prevention;
we may have many links to file and rm on one of those obviously
shouldn't prevent bind on top of another later on. To fix it
right way we need to mark _dentry_ as unsuitable for mounting
upon; new flag (DCACHE_CANT_MOUNT) is protected by d_flags and
i_mutex on the inode in question. Set it (with dont_mount(dentry))
in unlink/rmdir/etc., check (with cant_mount(dentry)) in places
in namespace.c that used to check for S_DEAD. Setting S_DEAD
is still needed in places where we used to set it (for directories
getting killed), since we rely on it for readdir/rmdir race
prevention.
2) rename()/mount() protection has another bogosity - we unhash
the target before we'd checked that it's not a mountpoint. Fixed.
3) ancient bogosity in pivot_root() - we locked i_mutex on the
right directory, but checked S_DEAD on the different (and wrong)
one. Noticed and fixed.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
According to specification
mkdir d; ln -s d a; open("a/", O_NOFOLLOW | O_RDONLY)
should return success but currently it returns ELOOP. This is a
regression caused by path lookup cleanup patch series.
Fix the code to ignore O_NOFOLLOW in case the provided path has trailing
slashes.
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Marius Tolzmann <tolzmann@molgen.mpg.de>
Acked-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Jan Kara <jack@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Lose want_dir argument, while we are at it - since now
nd->flags & LOOKUP_DIRECTORY is equivalent to it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We managed to lose O_DIRECTORY testing due to a stupid typo in commit
1f36f774b2 ("Switch !O_CREAT case to use of do_last()")
Reported-by: Walter Sheets <w41ter@gmail.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6: (33 commits)
quota: stop using QUOTA_OK / NO_QUOTA
dquot: cleanup dquot initialize routine
dquot: move dquot initialization responsibility into the filesystem
dquot: cleanup dquot drop routine
dquot: move dquot drop responsibility into the filesystem
dquot: cleanup dquot transfer routine
dquot: move dquot transfer responsibility into the filesystem
dquot: cleanup inode allocation / freeing routines
dquot: cleanup space allocation / freeing routines
ext3: add writepage sanity checks
ext3: Truncate allocated blocks if direct IO write fails to update i_size
quota: Properly invalidate caches even for filesystems with blocksize < pagesize
quota: generalize quota transfer interface
quota: sb_quota state flags cleanup
jbd: Delay discarding buffers in journal_unmap_buffer
ext3: quota_write cross block boundary behaviour
quota: drop permission checks from xfs_fs_set_xstate/xfs_fs_set_xquota
quota: split out compat_sys_quotactl support from quota.c
quota: split out netlink notification support from quota.c
quota: remove invalid optimization from quota_sync_all
...
Fixed trivial conflicts in fs/namei.c and fs/ufs/inode.c
Now that nd->last stays around until ->put_link() is called, we can
just postpone that ->put_link() in do_filp_open() a bit and don't
bother with copying.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
If we'd passed through 32 trailing symlinks already, there's
no sense following the 33rd - we'll bail out anyway. Better
bugger off earlier.
It *does* change behaviour, after a fashion - if the 33rd happens
to be a procfs-style symlink, original code *would* allow it.
This one will not. Cry me a river if that hurts you. Please, do.
And post a video of that, while you are at it.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Since do_last() doesn't mangle nd->last_name, we can safely postpone
__putname() done in handling of trailing symlinks until after the
call of do_last()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Brute-force separation of stuff reachable from do_last: with
the exception of do_link:; just take all that crap to a helper
function as-is and have it tell the caller if it has to go
to do_link.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
That's going to be a long and painful series. The first step:
take the stuff reachable from 'ok' label in do_filp_open() into
a new helper (finish_open()).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Currently various places in the VFS call vfs_dq_init directly. This means
we tie the quota code into the VFS. Get rid of that and make the
filesystem responsible for the initialization. For most metadata operations
this is a straight forward move into the methods, but for truncate and
open it's a bit more complicated.
For truncate we currently only call vfs_dq_init for the sys_truncate case
because open already takes care of it for ftruncate and open(O_TRUNC) - the
new code causes an additional vfs_dq_init for those which is harmless.
For open the initialization is moved from do_filp_open into the open method,
which means it happens slightly earlier now, and only for regular files.
The latter is fine because we don't need to initialize it for operations
on special files, and we already do it as part of the namespace operations
for directories.
Add a dquot_file_open helper that filesystems that support generic quotas
can use to fill in ->open.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jan Kara <jack@suse.cz>
Make sure that automount "symlinks" are followed regardless of LOOKUP_FOLLOW;
it should have no effect on them.
Cc: stable@kernel.org
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
ima_path_check actually deals with files! call it ima_file_check instead.
Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The "Untangling ima mess, part 2 with counters" patch messed
up the counters. Based on conversations with Al Viro, this patch
streamlines ima_path_check() by removing the counter maintaince.
The counters are now updated independently, from measuring the file,
in __dentry_open() and alloc_file() by calling ima_counts_get().
ima_path_check() is called from nfsd and do_filp_open().
It also did not measure all files that should have been measured.
Reason: ima_path_check() got bogus value passed as mask.
[AV: mea culpa]
[AV: add missing nfsd bits]
Signed-off-by: Mimi Zohar <zohar@us.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Some comments misspell "truly"; this fixes them. No code changes.
Signed-off-by: Adam Buchbinder <adam.buchbinder@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Instead of playing sick games with path saving, cleanups, just retry
the entire thing once with LOOKUP_REVAL added. Post-.34 we'll convert
all -ESTALE handling in there to that style, rather than playing with
many retry loops deep in the call chain.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
commit 5300990c03 had stepped on a rather
nasty mess: definitions of ACC_MODE used to be different. Fixed the
resulting breakage, converting them to variant that takes O_... value;
all callers have that and it actually simplifies life (see tomoyo part
of changes).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We end up trying to kfree() nd.last.name on open("/mnt/tmp", O_CREAT)
if /mnt/tmp is an autofs direct mount. The reason is that nd.last_type
is bogus here; we want LAST_BIND for everything of that kind and we
get LAST_NORM left over from finding parent directory.
So make sure that it *is* set properly; set to LAST_BIND before
doing ->follow_link() - for normal symlinks it will be changed
by __vfs_follow_link() and everything else needs it set that way.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
generic_permission was refusing CAP_DAC_READ_SEARCH-enabled
processes from opening DAC-protected files read-only, because
do_filp_open adds MAY_OPEN to the open mask.
Ignore MAY_OPEN. After this patch, CAP_DAC_READ_SEARCH is
again sufficient to open(fname, O_RDONLY) on a file to which
DAC otherwise refuses us read permission.
Reported-by: Mike Kazantsev <mk.fraggod@gmail.com>
Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Tested-by: Mike Kazantsev <mk.fraggod@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* pull ACC_MODE to fs.h; we have several copies all over the place
* nightmarish expression calculating f_mode by f_flags deserves a helper
too (OPEN_FMODE(flags))
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Just set f_flags when shoving struct file into nameidata; don't
postpone that until __dentry_open(). do_filp_open() has correct
value; lookup_instantiate_filp() doesn't - we lose the difference
between O_RDWR and 3 by that point.
We still set .intent.open.flags, so no fs code needs to be changed.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
We can't get to this point unless it's a valid pointer.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
procfs-style symlinks return a last_type of LAST_BIND without an actual
path string. This causes __follow_link to skip calling __vfs_follow_link
and so the dentry isn't revalidated.
This is a problem when the link target sits on NFSv4 as it depends on
the VFS to revalidate the dentry before using it on an open call. Ensure
that this occurs by forcing a revalidation of the target dentry of
LAST_BIND symlinks.
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Kill the 'update' argument of ima_path_check(), kill
dead code in ima.
Current rules: ima counters are bumped at the same time
when the file switches from put_filp() fodder to fput()
one. Which happens exactly in two places - alloc_file()
and __dentry_open(). Nothing else needs to do that at
all.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* do ima_get_count() in __dentry_open()
* stop doing that in followups
* move ima_path_check() to right after nameidata_to_filp()
* don't bump counters on it
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* take truncate logics into a helper (handle_truncate())
* rip it out of may_open()
* call it from the only caller of may_open() that might pass
O_TRUNC
* and do that after we'd finished with opening.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
All users outside of fs/ of get_empty_filp() have been removed. This patch
moves the definition from the include/ directory to internal.h so no new
users crop up and removes the EXPORT_SYMBOL. I'd love to see open intents
stop using it too, but that's a problem for another day and a smarter
developer!
Signed-off-by: Eric Paris <eparis@redhat.com>
Acked-by: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Use the sucker in other places in pathname resolution
that check MAY_EXEC for directories; lose the _lite
from name, it's equivalent of full-blown inode_permission()
for its callers (albeit still lighter, since large parts
of generic_permission() do not apply for pure MAY_EXEC).
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs-2.6: (21 commits)
ext3: PTR_ERR return of wrong pointer in setup_new_group_blocks()
ext3: Fix data / filesystem corruption when write fails to copy data
ext4: Support for 64-bit quota format
ext3: Support for vfsv1 quota format
quota: Implement quota format with 64-bit space and inode limits
quota: Move definition of QFMT_OCFS2 to linux/quota.h
ext2: fix comment in ext2_find_entry about return values
ext3: Unify log messages in ext3
ext2: clear uptodate flag on super block I/O error
ext2: Unify log messages in ext2
ext3: make "norecovery" an alias for "noload"
ext3: Don't update the superblock in ext3_statfs()
ext3: journal all modifications in ext3_xattr_set_handle
ext2: Explicitly assign values to on-disk enum of filetypes
quota: Fix WARN_ON in lookup_one_len
const: struct quota_format_ops
ubifs: remove manual O_SYNC handling
afs: remove manual O_SYNC handling
kill wait_on_page_writeback_range
vfs: Implement proper O_SYNC semantics
...
By teaching sysfs_revalidate to hide a dentry for
a sysfs_dirent if the sysfs_dirent has been renamed,
and by teaching sysfs_lookup to return the original
dentry if the sysfs dirent has been renamed. I can
show the results of renames correctly without having to
update the dcache during the directory rename.
This massively simplifies the rename logic allowing a lot
of weird sysfs special cases to be removed along with
a lot of now unnecesary helper code.
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Eric W. Biederman <ebiederm@aristanetworks.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Al Viro
