This averts the need to re-generate flags in fanotify_show_fdinfo()
and sets the scene for addition of more upcoming flags without growing
new members to the fanotify_data struct.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Add another mark type flag FAN_MARK_FILESYSTEM for add/remove/flush
of super block mark type.
A super block watch gets all events on the filesystem, regardless of
the mount from which the mark was added, unless an ignore mask exists
on either the inode or the mount where the event was generated.
Only one of FAN_MARK_MOUNT and FAN_MARK_FILESYSTEM mark type flags
may be provided to fanotify_mark() or no mark type flag for inode mark.
Cc: <linux-api@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Send events to group if super block mark mask matches the event
and unless the same group has an ignore mask on the vfsmount or
the inode on which the event occurred.
Soon, fanotify backend is going to support super block marks and
fanotify backend only supports path type events.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Add the infrastructure to attach a mark to a super_block struct
and detach all attached marks when super block is destroyed.
This is going to be used by fanotify backend to setup super block
marks.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Commit 92183a4289 ("fsnotify: fix ignore mask logic in
send_to_group()") acknoledges the use case of ignoring an event on
an inode mark, because of an ignore mask on a mount mark of the same
group (i.e. I want to get all events on this file, except for the events
that came from that mount).
This change depends on correctly merging the inode marks and mount marks
group lists, so that the mount mark ignore mask would be tested in
send_to_group(). Alas, the merging of the lists did not take into
account the case where event in question is not in the mask of any of
the mount marks.
To fix this, completely remove the tests for inode and mount event masks
from the lists merging code.
Fixes: 92183a4289 ("fsnotify: fix ignore mask logic in send_to_group")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
-----BEGIN PGP SIGNATURE-----
iQEzBAABCAAdFiEEq1nRK9aeMoq1VSgcnJ2qBz9kQNkFAluGfbAACgkQnJ2qBz9k
QNmkVQgAjv/tCHStwoQ4Hhr6q5wLU9apAW5WC7Or2MyNfqoJsKgyujpikwFMa0xY
wkVqlITYavvUKl/nRlQ6hpZtAY7hi1Y7GvIYs2ci6QO4YAUuBoH7qPLKqyZYzXx+
mBaC68885nMMDqIHvsCcLurwTiDer6XQXXPDmpMoO9g4kyVuhm2e0/M7CPaA4Ue9
WEfBPBROSNdRH7Wtww/MUvtfd+9mezdlpUQZVVO5cdhAVQ8pzW2g2piYtwIpaY7E
DiJ1zcgaqCnni+b69x4wz8TwB0q8wZJjrPfJgf4X7mIGBZrw80yNRlevfe5SxwdJ
mkMDvjaD0TEItvpjgTZReXaAjFOWTA==
=E61M
-----END PGP SIGNATURE-----
Merge tag 'for_v4.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
Pull misc fs fixes from Jan Kara:
- make UDF to properly mount media created by Win7
- make isofs to properly refuse devices with large physical block size
- fix a Spectre gadget in quotactl(2)
- fix a warning in fsnotify code hit by syzkaller
* tag 'for_v4.19-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
udf: Fix mounting of Win7 created UDF filesystems
udf: Remove dead code from udf_find_fileset()
fs/quota: Fix spectre gadget in do_quotactl
fs/quota: Replace XQM_MAXQUOTAS usage with MAXQUOTAS
isofs: reject hardware sector size > 2048 bytes
fsnotify: fix false positive warning on inode delete
Pull core signal handling updates from Eric Biederman:
"It was observed that a periodic timer in combination with a
sufficiently expensive fork could prevent fork from every completing.
This contains the changes to remove the need for that restart.
This set of changes is split into several parts:
- The first part makes PIDTYPE_TGID a proper pid type instead
something only for very special cases. The part starts using
PIDTYPE_TGID enough so that in __send_signal where signals are
actually delivered we know if the signal is being sent to a a group
of processes or just a single process.
- With that prep work out of the way the logic in fork is modified so
that fork logically makes signals received while it is running
appear to be received after the fork completes"
* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (22 commits)
signal: Don't send signals to tasks that don't exist
signal: Don't restart fork when signals come in.
fork: Have new threads join on-going signal group stops
fork: Skip setting TIF_SIGPENDING in ptrace_init_task
signal: Add calculate_sigpending()
fork: Unconditionally exit if a fatal signal is pending
fork: Move and describe why the code examines PIDNS_ADDING
signal: Push pid type down into complete_signal.
signal: Push pid type down into __send_signal
signal: Push pid type down into send_signal
signal: Pass pid type into do_send_sig_info
signal: Pass pid type into send_sigio_to_task & send_sigurg_to_task
signal: Pass pid type into group_send_sig_info
signal: Pass pid and pid type into send_sigqueue
posix-timers: Noralize good_sigevent
signal: Use PIDTYPE_TGID to clearly store where file signals will be sent
pid: Implement PIDTYPE_TGID
pids: Move the pgrp and session pid pointers from task_struct to signal_struct
kvm: Don't open code task_pid in kvm_vcpu_ioctl
pids: Compute task_tgid using signal->leader_pid
...
When inode is getting deleted and someone else holds reference to a mark
attached to the inode, we just detach the connector from the inode. In
that case fsnotify_put_mark() called from fsnotify_destroy_marks() will
decide to recalculate mask for the inode and __fsnotify_recalc_mask()
will WARN about invalid connector type:
WARNING: CPU: 1 PID: 12015 at fs/notify/mark.c:139
__fsnotify_recalc_mask+0x2d7/0x350 fs/notify/mark.c:139
Actually there's no reason to warn about detached connector in
__fsnotify_recalc_mask() so just silently skip updating the mask in such
case.
Reported-by: syzbot+c34692a51b9a6ca93540@syzkaller.appspotmail.com
Fixes: 3ac70bfcde ("fsnotify: add helper to get mask from connector")
Signed-off-by: Jan Kara <jack@suse.cz>
Merge updates from Andrew Morton:
- a few misc things
- a few Y2038 fixes
- ntfs fixes
- arch/sh tweaks
- ocfs2 updates
- most of MM
* emailed patches from Andrew Morton <akpm@linux-foundation.org>: (111 commits)
mm/hmm.c: remove unused variables align_start and align_end
fs/userfaultfd.c: remove redundant pointer uwq
mm, vmacache: hash addresses based on pmd
mm/list_lru: introduce list_lru_shrink_walk_irq()
mm/list_lru.c: pass struct list_lru_node* as an argument to __list_lru_walk_one()
mm/list_lru.c: move locking from __list_lru_walk_one() to its caller
mm/list_lru.c: use list_lru_walk_one() in list_lru_walk_node()
mm, swap: make CONFIG_THP_SWAP depend on CONFIG_SWAP
mm/sparse: delete old sparse_init and enable new one
mm/sparse: add new sparse_init_nid() and sparse_init()
mm/sparse: move buffer init/fini to the common place
mm/sparse: use the new sparse buffer functions in non-vmemmap
mm/sparse: abstract sparse buffer allocations
mm/hugetlb.c: don't zero 1GiB bootmem pages
mm, page_alloc: double zone's batchsize
mm/oom_kill.c: document oom_lock
mm/hugetlb: remove gigantic page support for HIGHMEM
mm, oom: remove sleep from under oom_lock
kernel/dma: remove unsupported gfp_mask parameter from dma_alloc_from_contiguous()
mm/cma: remove unsupported gfp_mask parameter from cma_alloc()
...
Patch series "Directed kmem charging", v8.
The Linux kernel's memory cgroup allows limiting the memory usage of the
jobs running on the system to provide isolation between the jobs. All
the kernel memory allocated in the context of the job and marked with
__GFP_ACCOUNT will also be included in the memory usage and be limited
by the job's limit.
The kernel memory can only be charged to the memcg of the process in
whose context kernel memory was allocated. However there are cases
where the allocated kernel memory should be charged to the memcg
different from the current processes's memcg. This patch series
contains two such concrete use-cases i.e. fsnotify and buffer_head.
The fsnotify event objects can consume a lot of system memory for large
or unlimited queues if there is either no or slow listener. The events
are allocated in the context of the event producer. However they should
be charged to the event consumer. Similarly the buffer_head objects can
be allocated in a memcg different from the memcg of the page for which
buffer_head objects are being allocated.
To solve this issue, this patch series introduces mechanism to charge
kernel memory to a given memcg. In case of fsnotify events, the memcg
of the consumer can be used for charging and for buffer_head, the memcg
of the page can be charged. For directed charging, the caller can use
the scope API memalloc_[un]use_memcg() to specify the memcg to charge
for all the __GFP_ACCOUNT allocations within the scope.
This patch (of 2):
A lot of memory can be consumed by the events generated for the huge or
unlimited queues if there is either no or slow listener. This can cause
system level memory pressure or OOMs. So, it's better to account the
fsnotify kmem caches to the memcg of the listener.
However the listener can be in a different memcg than the memcg of the
producer and these allocations happen in the context of the event
producer. This patch introduces remote memcg charging API which the
producer can use to charge the allocations to the memcg of the listener.
There are seven fsnotify kmem caches and among them allocations from
dnotify_struct_cache, dnotify_mark_cache, fanotify_mark_cache and
inotify_inode_mark_cachep happens in the context of syscall from the
listener. So, SLAB_ACCOUNT is enough for these caches.
The objects from fsnotify_mark_connector_cachep are not accounted as
they are small compared to the notification mark or events and it is
unclear whom to account connector to since it is shared by all events
attached to the inode.
The allocations from the event caches happen in the context of the event
producer. For such caches we will need to remote charge the allocations
to the listener's memcg. Thus we save the memcg reference in the
fsnotify_group structure of the listener.
This patch has also moved the members of fsnotify_group to keep the size
same, at least for 64 bit build, even with additional member by filling
the holes.
[shakeelb@google.com: use GFP_KERNEL_ACCOUNT rather than open-coding it]
Link: http://lkml.kernel.org/r/20180702215439.211597-1-shakeelb@google.com
Link: http://lkml.kernel.org/r/20180627191250.209150-2-shakeelb@google.com
Signed-off-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Roman Gushchin <guro@fb.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When f_setown is called a pid and a pid type are stored. Replace the use
of PIDTYPE_PID with PIDTYPE_TGID as PIDTYPE_TGID goes to the entire thread
group. Replace the use of PIDTYPE_MAX with PIDTYPE_PID as PIDTYPE_PID now
is only for a thread.
Update the users of __f_setown to use PIDTYPE_TGID instead of
PIDTYPE_PID.
For now the code continues to capture task_pid (when task_tgid would
really be appropriate), and iterate on PIDTYPE_PID (even when type ==
PIDTYPE_TGID) out of an abundance of caution to preserve existing
behavior.
Oleg Nesterov suggested using the test to ensure we use PIDTYPE_PID
for tgid lookup also be used to avoid taking the tasklist lock.
Suggested-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
The cost is the the same and this removes the need
to worry about complications that come from de_thread
and group_leader changing.
__task_pid_nr_ns has been updated to take advantage of this change.
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
The flag IN_MASK_CREATE is introduced as a flag for inotiy_add_watch()
which prevents inotify from modifying any existing watches when invoked.
If the pathname specified in the call has a watched inode associated
with it and IN_MASK_CREATE is specified, fail with an errno of EEXIST.
Use of IN_MASK_CREATE with IN_MASK_ADD is reserved for future use and
will return EINVAL.
RATIONALE
In the current implementation, there is no way to prevent
inotify_add_watch() from modifying existing watch descriptors. Even if
the caller keeps a record of all watch descriptors collected, this is
only sufficient to detect that an existing watch descriptor may have
been modified.
The assumption that a particular path will map to the same inode over
multiple calls to inotify_add_watch() cannot be made as files can be
renamed or deleted. It is also not possible to assume that two distinct
paths do no map to the same inode, due to hard-links or a dereferenced
symbolic link. Further uses of inotify_add_watch() to revert the change
may cause other watch descriptors to be modified or created, merely
compunding the problem. There is currently no system call such as
inotify_modify_watch() to explicity modify a watch descriptor, which
would be able to revert unwanted changes. Thus the caller cannot
guarantee to be able to revert any changes to existing watch decriptors.
Additionally the caller cannot assume that the events that are
associated with a watch descriptor are within the set requested, as any
future calls to inotify_add_watch() may unintentionally modify a watch
descriptor's mask. Thus it cannot currently be guaranteed that a watch
descriptor will only generate events which have been requested. The
program must filter events which come through its watch descriptor to
within its expected range.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Henry Wilson <henry.wilson@acentic.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Factor out helpers fanotify_add_mark() and fanotify_remove_mark()
to reduce duplicated code.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Use a helper to get the mask from the object (i.e. i_fsnotify_mask)
to generalize code of add/remove inode/vfsmount mark.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Make the code to attach/detach a connector to object more generic
by letting the fsnotify connector point to an abstract fsnotify_connp_t.
Code that needs to dereference an inode or mount object now uses the
helpers fsnotify_conn_{inode,mount}.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Instead of passing inode and vfsmount arguments to fsnotify_add_mark()
and its _locked variant, pass an abstract object pointer and the object
type.
The helpers fsnotify_obj_{inode,mount} are added to get the concrete
object pointer from abstract object pointer.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
The object marks manipulation functions fsnotify_destroy_marks()
fsnotify_find_mark() and their helpers take an argument of type
struct fsnotify_mark_connector __rcu ** to dereference the connector
pointer. use a typedef to describe this type for brevity.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Before changing the arguments of the functions fsnotify_add_mark()
and fsnotify_add_mark_locked(), convert most callers to use a wrapper.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Use fsnotify_foreach_obj_type macros to generalize the code that filters
events by marks mask and ignored_mask.
This is going to be used for adding mark of super block object type.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Use fsnotify_foreach_obj_type macros to generalize the code that filters
events by marks mask and ignored_mask.
This is going to be used for adding mark of super block object type.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Make some code that handles marks of object types inode and vfsmount
generic, so it can handle other object types.
Introduce fsnotify_foreach_obj_type macro to iterate marks by object type
and fsnotify_iter_{should|set}_report_type macros to set/test report_mask.
This is going to be used for adding mark of another object type
(super block mark).
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Introduce helpers fsnotify_iter_select_report_types() and
fsnotify_iter_next() to abstract the inode/vfsmount marks merged
list iteration.
This is a preparation patch before generalizing mark list
iteration to more mark object types (i.e. super block marks).
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
inode_mark and vfsmount_mark arguments are passed to handle_event()
operation as function arguments as well as on iter_info struct.
The difference is that iter_info struct may contain marks that should
not be handled and are represented as NULL arguments to inode_mark or
vfsmount_mark.
Instead of passing the inode_mark and vfsmount_mark arguments, add
a report_mask member to iter_info struct to indicate which marks should
be handled, versus marks that should only be kept alive during user
wait.
This change is going to be used for passing more mark types
with handle_event() (i.e. super block marks).
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
An fsnotify_mark_connector is referencing a single type of object
(either inode or vfsmount). Instead of storing a type mask in
connector->flags, store a single type id in connector->type to
identify the type of object.
When a connector object is detached from the object, its type is set
to FSNOTIFY_OBJ_TYPE_DETACHED and this object is not going to be
reused.
The function fsnotify_clear_marks_by_group() is the only place where
type mask was used, so use type flags instead of type id to this
function.
This change is going to be more convenient when adding a new object
type (super block).
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
The ignore mask logic in send_to_group() does not match the logic
in fanotify_should_send_event(). In the latter, a vfsmount mark ignore
mask precedes an inode mark mask and in the former, it does not.
That difference may cause events to be sent to fanotify backend for no
reason. Fix the logic in send_to_group() to match that of
fanotify_should_send_event().
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
When event on child inodes are sent to the parent inode mark and
parent inode mark was not marked with FAN_EVENT_ON_CHILD, the event
will not be delivered to the listener process. However, if the same
process also has a mount mark, the event to the parent inode will be
delivered regadless of the mount mark mask.
This behavior is incorrect in the case where the mount mark mask does
not contain the specific event type. For example, the process adds
a mark on a directory with mask FAN_MODIFY (without FAN_EVENT_ON_CHILD)
and a mount mark with mask FAN_CLOSE_NOWRITE (without FAN_ONDIR).
A modify event on a file inside that directory (and inside that mount)
should not create a FAN_MODIFY event, because neither of the marks
requested to get that event on the file.
Fixes: 1968f5eed5 ("fanotify: use both marks when possible")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Pull misc filesystem updates from Jan Kara:
"udf, ext2, quota, fsnotify fixes & cleanups:
- udf fixes for handling of media without uid/gid
- udf fixes for some corner cases in parsing of volume recognition
sequence
- improvements of fsnotify handling of ENOMEM
- new ioctl to allow setting of watch descriptor id for inotify (for
checkpoint - restart)
- small ext2, reiserfs, quota cleanups"
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
quota: Kill an unused extern entry form quota.h
reiserfs: Remove VLA from fs/reiserfs/reiserfs.h
udf: fix potential refcnt problem of nls module
ext2: change return code to -ENOMEM when failing memory allocation
udf: Do not mark possibly inconsistent filesystems as closed
fsnotify: Let userspace know about lost events due to ENOMEM
fanotify: Avoid lost events due to ENOMEM for unlimited queues
udf: Remove never implemented mount options
udf: Update mount option documentation
udf: Provide saner default for invalid uid / gid
udf: Clean up handling of invalid uid/gid
udf: Apply uid/gid mount options also to new inodes & chown
udf: Ignore [ug]id=ignore mount options
udf: Fix handling of Partition Descriptors
udf: Unify common handling of descriptors
udf: Convert descriptor index definitions to enum
udf: Allow volume descriptor sequence to be terminated by unrecorded block
udf: Simplify handling of Volume Descriptor Pointers
udf: Fix off-by-one in volume descriptor sequence length
inotify: Extend ioctl to allow to request id of new watch descriptor
Using the fs-internal do_fanotify_mark() helper allows us to get rid of
the fs-internal call to the sys_fanotify_mark() syscall.
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Acked-by: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Using the inotify-internal do_inotify_init() helper allows us to get rid
of the in-kernel call to sys_inotify_init1() syscall.
This patch is part of a series which removes in-kernel calls to syscalls.
On this basis, the syscall entry path can be streamlined. For details, see
http://lkml.kernel.org/r/20180325162527.GA17492@light.dominikbrodowski.net
Acked-by: Jan Kara <jack@suse.cz>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>
Currently if notification event is lost due to event allocation failing
we ENOMEM, we just silently continue (except for fanotify permission
events where we deny the access). This is undesirable as userspace has
no way of knowing whether the notifications it got are complete or not.
Treat lost events due to ENOMEM the same way as lost events due to queue
overflow so that userspace knows something bad happened and it likely
needs to rescan the filesystem.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Fanotify queues of unlimited length do not expect events can be lost.
Since these queues are used for system auditing and other security
related tasks, loosing events can even have security implications.
Currently, since the allocation is small (32-bytes), it cannot fail
however when we start accounting events in memcgs, allocation can start
failing. So avoid loosing events due to failure to allocate memory by
making event allocation use __GFP_NOFAIL.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Watch descriptor is id of the watch created by inotify_add_watch().
It is allocated in inotify_add_to_idr(), and takes the numbers
starting from 1. Every new inotify watch obtains next available
number (usually, old + 1), as served by idr_alloc_cyclic().
CRIU (Checkpoint/Restore In Userspace) project supports inotify
files, and restores watched descriptors with the same numbers,
they had before dump. Since there was no kernel support, we
had to use cycle to add a watch with specific descriptor id:
while (1) {
int wd;
wd = inotify_add_watch(inotify_fd, path, mask);
if (wd < 0) {
break;
} else if (wd == desired_wd_id) {
ret = 0;
break;
}
inotify_rm_watch(inotify_fd, wd);
}
(You may find the actual code at the below link:
https://github.com/checkpoint-restore/criu/blob/v3.7/criu/fsnotify.c#L577)
The cycle is suboptiomal and very expensive, but since there is no better
kernel support, it was the only way to restore that. Happily, we had met
mostly descriptors with small id, and this approach had worked somehow.
But recent time containers with inotify with big watch descriptors
begun to come, and this way stopped to work at all. When descriptor id
is something about 0x34d71d6, the restoring process spins in busy loop
for a long time, and the restore hungs and delay of migration from node
to node could easily be watched.
This patch aims to solve this problem. It introduces new ioctl
INOTIFY_IOC_SETNEXTWD, which allows to request the number of next created
watch descriptor from userspace. It simply calls idr_set_cursor() primitive
to populate idr::idr_next, so that next idr_alloc_cyclic() allocation
will return this id, if it is not occupied. This is the way which is
used to restore some other resources from userspace. For example,
/proc/sys/kernel/ns_last_pid works the same for task pids.
The new code is under CONFIG_CHECKPOINT_RESTORE #define, so small system
may exclude it.
v2: Use INT_MAX instead of custom definition of max id,
as IDR subsystem guarantees id is between 0 and INT_MAX.
CC: Jan Kara <jack@suse.cz>
CC: Matthew Wilcox <willy@infradead.org>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
Reviewed-by: Cyrill Gorcunov <gorcunov@openvz.org>
Reviewed-by: Matthew Wilcox <mawilcox@microsoft.com>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jan Kara <jack@suse.cz>
This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:
for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
done
with de-mangling cleanups yet to come.
NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do. But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.
The next patch from Al will sort out the final differences, and we
should be all done.
Scripted-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull poll annotations from Al Viro:
"This introduces a __bitwise type for POLL### bitmap, and propagates
the annotations through the tree. Most of that stuff is as simple as
'make ->poll() instances return __poll_t and do the same to local
variables used to hold the future return value'.
Some of the obvious brainos found in process are fixed (e.g. POLLIN
misspelled as POLL_IN). At that point the amount of sparse warnings is
low and most of them are for genuine bugs - e.g. ->poll() instance
deciding to return -EINVAL instead of a bitmap. I hadn't touched those
in this series - it's large enough as it is.
Another problem it has caught was eventpoll() ABI mess; select.c and
eventpoll.c assumed that corresponding POLL### and EPOLL### were
equal. That's true for some, but not all of them - EPOLL### are
arch-independent, but POLL### are not.
The last commit in this series separates userland POLL### values from
the (now arch-independent) kernel-side ones, converting between them
in the few places where they are copied to/from userland. AFAICS, this
is the least disruptive fix preserving poll(2) ABI and making epoll()
work on all architectures.
As it is, it's simply broken on sparc - try to give it EPOLLWRNORM and
it will trigger only on what would've triggered EPOLLWRBAND on other
architectures. EPOLLWRBAND and EPOLLRDHUP, OTOH, are never triggered
at all on sparc. With this patch they should work consistently on all
architectures"
* 'misc.poll' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (37 commits)
make kernel-side POLL... arch-independent
eventpoll: no need to mask the result of epi_item_poll() again
eventpoll: constify struct epoll_event pointers
debugging printk in sg_poll() uses %x to print POLL... bitmap
annotate poll(2) guts
9p: untangle ->poll() mess
->si_band gets POLL... bitmap stored into a user-visible long field
ring_buffer_poll_wait() return value used as return value of ->poll()
the rest of drivers/*: annotate ->poll() instances
media: annotate ->poll() instances
fs: annotate ->poll() instances
ipc, kernel, mm: annotate ->poll() instances
net: annotate ->poll() instances
apparmor: annotate ->poll() instances
tomoyo: annotate ->poll() instances
sound: annotate ->poll() instances
acpi: annotate ->poll() instances
crypto: annotate ->poll() instances
block: annotate ->poll() instances
x86: annotate ->poll() instances
...
This is a pure automated search-and-replace of the internal kernel
superblock flags.
The s_flags are now called SB_*, with the names and the values for the
moment mirroring the MS_* flags that they're equivalent to.
Note how the MS_xyz flags are the ones passed to the mount system call,
while the SB_xyz flags are what we then use in sb->s_flags.
The script to do this was:
# places to look in; re security/*: it generally should *not* be
# touched (that stuff parses mount(2) arguments directly), but
# there are two places where we really deal with superblock flags.
FILES="drivers/mtd drivers/staging/lustre fs ipc mm \
include/linux/fs.h include/uapi/linux/bfs_fs.h \
security/apparmor/apparmorfs.c security/apparmor/include/lib.h"
# the list of MS_... constants
SYMS="RDONLY NOSUID NODEV NOEXEC SYNCHRONOUS REMOUNT MANDLOCK \
DIRSYNC NOATIME NODIRATIME BIND MOVE REC VERBOSE SILENT \
POSIXACL UNBINDABLE PRIVATE SLAVE SHARED RELATIME KERNMOUNT \
I_VERSION STRICTATIME LAZYTIME SUBMOUNT NOREMOTELOCK NOSEC BORN \
ACTIVE NOUSER"
SED_PROG=
for i in $SYMS; do SED_PROG="$SED_PROG -e s/MS_$i/SB_$i/g"; done
# we want files that contain at least one of MS_...,
# with fs/namespace.c and fs/pnode.c excluded.
L=$(for i in $SYMS; do git grep -w -l MS_$i $FILES; done| sort|uniq|grep -v '^fs/namespace.c'|grep -v '^fs/pnode.c')
for f in $L; do sed -i $f $SED_PROG; done
Requested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pull quota, ext2, isofs and udf fixes from Jan Kara:
- two small quota error handling fixes
- two isofs fixes for architectures with signed char
- several udf block number overflow and signedness fixes
- ext2 rework of mount option handling to avoid GFP_KERNEL allocation
with spinlock held
- ... it also contains a patch to implement auditing of responses to
fanotify permission events. That should have been in the fanotify
pull request but I mistakenly merged that patch into a wrong branch
and noticed only now at which point I don't think it's worth rebasing
and redoing.
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
quota: be aware of error from dquot_initialize
quota: fix potential infinite loop
isofs: use unsigned char types consistently
isofs: fix timestamps beyond 2027
udf: Fix some sign-conversion warnings
udf: Fix signed/unsigned format specifiers
udf: Fix 64-bit sign extension issues affecting blocks > 0x7FFFFFFF
udf: Remove some outdate references from documentation
udf: Avoid overflow when session starts at large offset
ext2: Fix possible sleep in atomic during mount option parsing
ext2: Parse mount options into a dedicated structure
audit: Record fanotify access control decisions
Pull fsnotify updates from Jan Kara:
- fixes of use-after-tree issues when handling fanotify permission
events from Miklos
- refcount_t conversions from Elena
- fixes of ENOMEM handling in dnotify and fsnotify from me
* 'fsnotify' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
fsnotify: convert fsnotify_mark.refcnt from atomic_t to refcount_t
fanotify: clean up CONFIG_FANOTIFY_ACCESS_PERMISSIONS ifdefs
fsnotify: clean up fsnotify()
fanotify: fix fsnotify_prepare_user_wait() failure
fsnotify: fix pinning group in fsnotify_prepare_user_wait()
fsnotify: pin both inode and vfsmount mark
fsnotify: clean up fsnotify_prepare/finish_user_wait()
fsnotify: convert fsnotify_group.refcnt from atomic_t to refcount_t
fsnotify: Protect bail out path of fsnotify_add_mark_locked() properly
dnotify: Handle errors from fsnotify_add_mark_locked() in fcntl_dirnotify()
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.
By default all files without license information are under the default
license of the kernel, which is GPL version 2.
Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.
This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.
How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,
Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.
The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.
The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.
Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if <5
lines).
All documentation files were explicitly excluded.
The following heuristics were used to determine which SPDX license
identifiers to apply.
- when both scanners couldn't find any license traces, file was
considered to have no license information in it, and the top level
COPYING file license applied.
For non */uapi/* files that summary was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 11139
and resulted in the first patch in this series.
If that file was a */uapi/* path one, it was "GPL-2.0 WITH
Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was:
SPDX license identifier # files
---------------------------------------------------|-------
GPL-2.0 WITH Linux-syscall-note 930
and resulted in the second patch in this series.
- if a file had some form of licensing information in it, and was one
of the */uapi/* ones, it was denoted with the Linux-syscall-note if
any GPL family license was found in the file or had no licensing in
it (per prior point). Results summary:
SPDX license identifier # files
---------------------------------------------------|------
GPL-2.0 WITH Linux-syscall-note 270
GPL-2.0+ WITH Linux-syscall-note 169
((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21
((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17
LGPL-2.1+ WITH Linux-syscall-note 15
GPL-1.0+ WITH Linux-syscall-note 14
((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5
LGPL-2.0+ WITH Linux-syscall-note 4
LGPL-2.1 WITH Linux-syscall-note 3
((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3
((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1
and that resulted in the third patch in this series.
- when the two scanners agreed on the detected license(s), that became
the concluded license(s).
- when there was disagreement between the two scanners (one detected a
license but the other didn't, or they both detected different
licenses) a manual inspection of the file occurred.
- In most cases a manual inspection of the information in the file
resulted in a clear resolution of the license that should apply (and
which scanner probably needed to revisit its heuristics).
- When it was not immediately clear, the license identifier was
confirmed with lawyers working with the Linux Foundation.
- If there was any question as to the appropriate license identifier,
the file was flagged for further research and to be revisited later
in time.
In total, over 70 hours of logged manual review was done on the
spreadsheet to determine the SPDX license identifiers to apply to the
source files by Kate, Philippe, Thomas and, in some cases, confirmation
by lawyers working with the Linux Foundation.
Kate also obtained a third independent scan of the 4.13 code base from
FOSSology, and compared selected files where the other two scanners
disagreed against that SPDX file, to see if there was new insights. The
Windriver scanner is based on an older version of FOSSology in part, so
they are related.
Thomas did random spot checks in about 500 files from the spreadsheets
for the uapi headers and agreed with SPDX license identifier in the
files he inspected. For the non-uapi files Thomas did random spot checks
in about 15000 files.
In initial set of patches against 4.14-rc6, 3 files were found to have
copy/paste license identifier errors, and have been fixed to reflect the
correct identifier.
Additionally Philippe spent 10 hours this week doing a detailed manual
inspection and review of the 12,461 patched files from the initial patch
version early this week with:
- a full scancode scan run, collecting the matched texts, detected
license ids and scores
- reviewing anything where there was a license detected (about 500+
files) to ensure that the applied SPDX license was correct
- reviewing anything where there was no detection but the patch license
was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied
SPDX license was correct
This produced a worksheet with 20 files needing minor correction. This
worksheet was then exported into 3 different .csv files for the
different types of files to be modified.
These .csv files were then reviewed by Greg. Thomas wrote a script to
parse the csv files and add the proper SPDX tag to the file, in the
format that the file expected. This script was further refined by Greg
based on the output to detect more types of files automatically and to
distinguish between header and source .c files (which need different
comment types.) Finally Greg ran the script using the .csv files to
generate the patches.
Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org>
Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
atomic_t variables are currently used to implement reference
counters with the following properties:
- counter is initialized to 1 using atomic_set()
- a resource is freed upon counter reaching zero
- once counter reaches zero, its further
increments aren't allowed
- counter schema uses basic atomic operations
(set, inc, inc_not_zero, dec_and_test, etc.)
Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.
The variable fsnotify_mark.refcnt is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
The only negative from this patch should be an addition of 32bytes to
'struct fsnotify_group' if CONFIG_FANOTIFY_ACCESS_PERMISSIONS is not
defined.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Use helpers to get first and next marks from connector.
Also get rid of inode_node/vfsmount_node local variables, which just refers
to the same objects as iter_info. There was an srcu_dereference() for
foo_node, but that's completely superfluous since we've already done it
when obtaining foo_node.
Also get rid of inode_group/vfsmount_group local variables; checking
against non-NULL for these is the same as checking against non-NULL
inode_mark/vfsmount_mark.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
If fsnotify_prepare_user_wait() fails, we leave the event on the
notification list. Which will result in a warning in
fsnotify_destroy_event() and later use-after-free.
Instead of adding a new helper to remove the event from the list in this
case, I opted to move the prepare/finish up into fanotify_handle_event().
This will allow these to be moved further out into the generic code later,
and perhaps let us move to non-sleeping RCU.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 05f0e38724 ("fanotify: Release SRCU lock when waiting for userspace response")
Cc: <stable@vger.kernel.org> # v4.12
Signed-off-by: Jan Kara <jack@suse.cz>
Blind increment of group's user_waits is not enough, we could be far enough
in the group's destruction that it isn't taken into account (i.e. grabbing
the mark ref afterwards doesn't guarantee that it was the ref coming from
the _group_ that was grabbed).
Instead we need to check (under lock) that the mark is still attached to
the group after having obtained a ref to the mark. If not, skip it.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 9385a84d7e ("fsnotify: Pass fsnotify_iter_info into handle_event handler")
Cc: <stable@vger.kernel.org> # v4.12
Signed-off-by: Jan Kara <jack@suse.cz>
We may fail to pin one of the marks in fsnotify_prepare_user_wait() when
dropping the srcu read lock, resulting in use after free at the next
iteration.
Solution is to store both marks in iter_info instead of just the one we'll
be sending the event for.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Fixes: 9385a84d7e ("fsnotify: Pass fsnotify_iter_info into handle_event handler")
Cc: <stable@vger.kernel.org> # v4.12
Signed-off-by: Jan Kara <jack@suse.cz>
This patch doesn't actually fix any bug, just paves the way for fixing mark
and group pinning.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Cc: <stable@vger.kernel.org> # v4.12
Signed-off-by: Jan Kara <jack@suse.cz>
atomic_t variables are currently used to implement reference
counters with the following properties:
- counter is initialized to 1 using atomic_set()
- a resource is freed upon counter reaching zero
- once counter reaches zero, its further
increments aren't allowed
- counter schema uses basic atomic operations
(set, inc, inc_not_zero, dec_and_test, etc.)
Such atomic variables should be converted to a newly provided
refcount_t type and API that prevents accidental counter overflows
and underflows. This is important since overflows and underflows
can lead to use-after-free situation and be exploitable.
The variable fsnotify_group.refcnt is used as pure reference counter.
Convert it to refcount_t and fix up the operations.
Suggested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: David Windsor <dwindsor@gmail.com>
Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Jan Kara <jack@suse.cz>
When fsnotify_add_mark_locked() fails it cleans up the mark it was
adding. Since the mark is already visible in group's list, we should
protect update of mark->flags with mark->lock. I'm not aware of any real
issues this could cause (since we also hold group->mark_mutex) but
better be safe and obey locking rules properly.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
fsnotify_add_mark_locked() can fail but we do not check its return
value. This didn't matter before commit 9dd813c15b "fsnotify: Move
mark list head from object into dedicated structure" as none of possible
failures could happen for dnotify but after that commit -ENOMEM can be
returned. Handle this error properly in fcntl_dirnotify() as
otherwise we just hit BUG_ON(dn_mark->dn) in dnotify_free_mark().
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reported-by: syzkaller
Fixes: 9dd813c15b
Signed-off-by: Jan Kara <jack@suse.cz>
This patch fixes some spelling typos found in Kconfig files.
Signed-off-by: Masanari Iida <standby24x7@gmail.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
The fanotify interface allows user space daemons to make access
control decisions. Under common criteria requirements, we need to
optionally record decisions based on policy. This patch adds a bit mask,
FAN_AUDIT, that a user space daemon can 'or' into the response decision
which will tell the kernel that it made a decision and record it.
It would be used something like this in user space code:
response.response = FAN_DENY | FAN_AUDIT;
write(fd, &response, sizeof(struct fanotify_response));
When the syscall ends, the audit system will record the decision as a
AUDIT_FANOTIFY auxiliary record to denote that the reason this event
occurred is the result of an access control decision from fanotify
rather than DAC or MAC policy.
A sample event looks like this:
type=PATH msg=audit(1504310584.332:290): item=0 name="./evil-ls"
inode=1319561 dev=fc:03 mode=0100755 ouid=1000 ogid=1000 rdev=00:00
obj=unconfined_u:object_r:user_home_t:s0 nametype=NORMAL
type=CWD msg=audit(1504310584.332:290): cwd="/home/sgrubb"
type=SYSCALL msg=audit(1504310584.332:290): arch=c000003e syscall=2
success=no exit=-1 a0=32cb3fca90 a1=0 a2=43 a3=8 items=1 ppid=901
pid=959 auid=1000 uid=1000 gid=1000 euid=1000 suid=1000
fsuid=1000 egid=1000 sgid=1000 fsgid=1000 tty=pts1 ses=3 comm="bash"
exe="/usr/bin/bash" subj=unconfined_u:unconfined_r:unconfined_t:
s0-s0:c0.c1023 key=(null)
type=FANOTIFY msg=audit(1504310584.332:290): resp=2
Prior to using the audit flag, the developer needs to call
fanotify_init or'ing in FAN_ENABLE_AUDIT to ensure that the kernel
supports auditing. The calling process must also have the CAP_AUDIT_WRITE
capability.
Signed-off-by: sgrubb <sgrubb@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
take_dentry_name_snapshot() takes a safe snapshot of dentry name;
if the name is a short one, it gets copied into caller-supplied
structure, otherwise an extra reference to external name is grabbed
(those are never modified). In either case the pointer to stable
string is stored into the same structure.
dentry must be held by the caller of take_dentry_name_snapshot(),
but may be freely dropped afterwards - the snapshot will stay
until destroyed by release_dentry_name_snapshot().
Intended use:
struct name_snapshot s;
take_dentry_name_snapshot(&s, dentry);
...
access s.name
...
release_dentry_name_snapshot(&s);
Replaces fsnotify_oldname_...(), gets used in fsnotify to obtain the name
to pass down with event.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
When delivering an event to userspace for a file on an NFS share,
if the file is deleted on server side before user reads the event,
user will not get the event.
If the event queue contained several events, the stale event is
quietly dropped and read() returns to user with events read so far
in the buffer.
If the event queue contains a single stale event or if the stale
event is a permission event, read() returns to user with the kernel
internal error code 518 (EOPENSTALE), which is not a POSIX error code.
Check the internal return value -EOPENSTALE in fanotify_read(), just
the same as it is checked in path_openat() and drop the event in the
cases that it is not already dropped.
This is a reproducer from Marko Rauhamaa:
Just take the example program listed under "man fanotify" ("fantest")
and follow these steps:
==============================================================
NFS Server NFS Client(1) NFS Client(2)
==============================================================
# echo foo >/nfsshare/bar.txt
# cat /nfsshare/bar.txt
foo
# ./fantest /nfsshare
Press enter key to terminate.
Listening for events.
# rm -f /nfsshare/bar.txt
# cat /nfsshare/bar.txt
read: Unknown error 518
cat: /nfsshare/bar.txt: Operation not permitted
==============================================================
where NFS Client (1) and (2) are two terminal sessions on a single NFS
Client machine.
Reported-by: Marko Rauhamaa <marko.rauhamaa@f-secure.com>
Tested-by: Marko Rauhamaa <marko.rauhamaa@f-secure.com>
Cc: <linux-api@vger.kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
We recently shifted this code around, so we're no longer holding the
lock on this path.
Fixes: 755b5bc681 ("fsnotify: Remove indirection from mark list addition")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Pointer to ->free_mark callback unnecessarily occupies one long in each
fsnotify_mark although they are the same for all marks from one
notification group. Move the callback pointer to fsnotify_ops.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently we initialize mark->group only in fsnotify_add_mark_lock().
However we will need to access fsnotify_ops of corresponding group from
fsnotify_put_mark() so we need mark->group initialized earlier. Do that
in fsnotify_init_mark() which has a consequence that once
fsnotify_init_mark() is called on a mark, the mark has to be destroyed
by fsnotify_put_mark().
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
inode_mark.c now contains only a single function. Move it to
fs/notify/fsnotify.c and remove inode_mark.c.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
These are very thin wrappers, just remove them. Drop
fs/notify/vfsmount_mark.c as it is empty now.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
The function is already mostly contained in what
fsnotify_clear_marks_by_group() does. Just update that function to not
select marks when all of them should be destroyed and remove
fsnotify_detach_group_marks().
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
The _flags() suffix in the function name was more confusing than
explaining so just remove it. Also rename the argument from 'flags' to
'type' to better explain what the function expects.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Inline these helpers as they are very thin. We still keep them as we
don't want to expose details about how list type is determined.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
These helpers are just very thin wrappers now. Remove them.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
These helpers are now only a simple assignment and just obfuscate
what is going on. Remove them.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
When userspace task processing fanotify permission events screws up and
does not respond, fsnotify_mark_srcu SRCU is held indefinitely which
causes further hangs in the whole notification subsystem. Although we
cannot easily solve the problem of operations blocked waiting for
response from userspace, we can at least somewhat localize the damage by
dropping SRCU lock before waiting for userspace response and reacquiring
it when userspace responds.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Pass fsnotify_iter_info into ->handle_event() handler so that it can
release and reacquire SRCU lock via fsnotify_prepare_user_wait() and
fsnotify_finish_user_wait() functions. These functions also make sure
current marks are appropriately pinned so that iteration protected by
srcu in fsnotify() stays safe.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
fanotify wants to drop fsnotify_mark_srcu lock when waiting for response
from userspace so that the whole notification subsystem is not blocked
during that time. This patch provides a framework for safely getting
mark reference for a mark found in the object list which pins the mark
in that list. We can then drop fsnotify_mark_srcu, wait for userspace
response and then safely continue iteration of the object list once we
reaquire fsnotify_mark_srcu.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently we queue all marks for destruction on group shutdown and then
destroy them from fsnotify_destroy_group() instead from a worker thread
which is the usual path. However worker can already be processing some
list of marks to destroy so this does not make 100% all marks are really
destroyed by the time group is shut down. This isn't a big problem as
each mark holds group reference and thus group stays partially alive
until all marks are really freed but there's no point in complicating
our lives - just wait for the delayed work to be finished instead.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Instead of removing mark from object list from fsnotify_detach_mark(),
remove the mark when last reference to the mark is dropped. This will
allow fanotify to wait for userspace response to event without having to
hold onto fsnotify_mark_srcu.
To avoid pinning inodes by elevated refcount (and thus e.g. delaying
file deletion) while someone holds mark reference, we detach connector
from the object also from fsnotify_destroy_marks() and not only after
removing last mark from the list as it was now.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently we queue mark into a list of marks for destruction in
__fsnotify_free_mark() and keep the last mark reference dangling. After the
worker waits for SRCU period, it drops the last reference to the mark
which frees it. This scheme has the disadvantage that if we hold
reference to a mark and drop and reacquire SRCU lock, the mark can get
freed immediately which is slightly inconvenient and we will need to
avoid this in the future.
Move to a scheme where queueing of mark into a list of marks for
destruction happens when the last reference to the mark is dropped. Also
drop reference to the mark held by group list already when mark is
removed from that list instead of dropping it only from the destruction
worker.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Dropping mark reference can result in mark being freed. Although it
should not happen in inotify_remove_from_idr() since caller should hold
another reference, just don't risk lock up just after WARN_ON
unnecessarily. Also fold do_inotify_remove_from_idr() into the single
callsite as that function really is just two lines of real code.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently we free fsnotify_mark_connector structure only when inode /
vfsmount is getting freed. This can however impose noticeable memory
overhead when marks get attached to inodes only temporarily. So free the
connector structure once the last mark is detached from the object.
Since notification infrastructure can be working with the connector
under the protection of fsnotify_mark_srcu, we have to be careful and
free the fsnotify_mark_connector only after SRCU period passes.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
So far list of marks attached to an object (inode / vfsmount) was
protected by i_lock or mnt_root->d_lock. This dictates that the list
must be empty before the object can be destroyed although the list is
now anchored in the fsnotify_mark_connector structure. Protect the list
by a spinlock in the fsnotify_mark_connector structure to decouple
lifetime of a list of marks from a lifetime of the object. This also
simplifies the code quite a bit since we don't have to differentiate
between inode and vfsmount lists in quite a few places anymore.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
After removing all the indirection it is clear that
hlist_del_init_rcu(&mark->obj_list);
in fsnotify_destroy_marks() is not needed as the mark gets removed from
the list shortly afterwards in fsnotify_destroy_mark() ->
fsnotify_detach_mark() -> fsnotify_detach_from_object(). Also there is
no problem with mark being visible on object list while we call
fsnotify_destroy_mark() as parallel destruction of marks from several
places is properly handled (as mentioned in the comment in
fsnotify_destroy_marks(). So just remove the list removal and also the
stale comment.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
We lock object list lock in fsnotify_detach_from_object() twice - once
to detach mark and second time to recalculate mask. That is unnecessary
and later it will become problematic as we will free the connector as
soon as there is no mark in it. So move recalculation of fsnotify mask
into the same critical section that is detaching mark.
This also removes recalculation of child dentry flags from
fsnotify_detach_from_object(). That is however fine. Those marks will
get recalculated once some event happens on a child.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
fsnotify_detach_mark() calls fsnotify_destroy_inode_mark() or
fsnotify_destroy_vfsmount_mark() to remove mark from object list. These
two functions are however very similar and differ only in the lock they
use to protect the object list of marks. Simplify the code by removing
the indirection and removing mark from the object list in a common
function.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Instead of passing spinlock into fsnotify_destroy_marks() determine it
directly in that function from the connector type. This will reduce code
churn when changing lock protecting list of marks.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Move locking of a mark list into fsnotify_find_mark(). This reduces code
churn in the following patch changing lock protecting the list.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Move locking of locks protecting a list of marks into
fsnotify_recalc_mask(). This reduces code churn in the following patch
which changes the lock protecting the list of marks.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Move fsnotify_destroy_marks() to be later in the fs/notify/mark.c. It
will need some functions that are declared after its current
declaration. No functional change.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Adding notification mark to object list has been currently done through
fsnotify_add_{inode|vfsmount}_mark() helpers from
fsnotify_add_mark_locked() which call fsnotify_add_mark_list(). Remove
this unnecessary indirection to simplify the code.
Pushing all the locking to fsnotify_add_mark_list() also allows us to
allocate the connector structure with GFP_KERNEL mode.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently inode reference is held by fsnotify marks. Change the rules so
that inode reference is held by fsnotify_mark_connector structure
whenever the list is non-empty. This simplifies the code and is more
logical.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Move pointer to inode / vfsmount from mark itself to the
fsnotify_mark_connector structure. This is another step on the path
towards decoupling inode / vfsmount lifetime from notification mark
lifetime.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Currently notification marks are attached to object (inode or vfsmnt) by
a hlist_head in the object. The list is also protected by a spinlock in
the object. So while there is any mark attached to the list of marks,
the object must be pinned in memory (and thus e.g. last iput() deleting
inode cannot happen). Also for list iteration in fsnotify() to work, we
must hold fsnotify_mark_srcu lock so that mark itself and
mark->obj_list.next cannot get freed. Thus we are required to wait for
response to fanotify events from userspace process with
fsnotify_mark_srcu lock held. That causes issues when userspace process
is buggy and does not reply to some event - basically the whole
notification subsystem gets eventually stuck.
So to be able to drop fsnotify_mark_srcu lock while waiting for
response, we have to pin the mark in memory and make sure it stays in
the object list (as removing the mark waiting for response could lead to
lost notification events for groups later in the list). However we don't
want inode reclaim to block on such mark as that would lead to system
just locking up elsewhere.
This commit is the first in the series that paves way towards solving
these conflicting lifetime needs. Instead of anchoring the list of marks
directly in the object, we anchor it in a dedicated structure
(fsnotify_mark_connector) and just point to that structure from the
object. The following commits will also add spinlock protecting the list
and object pointer to the structure.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Add a comment that lifetime of a notification mark is protected by SRCU
and remove a comment about clearing of marks attached to the inode. It
is stale and more uptodate version is at fsnotify_destroy_marks() which
is the function handling this case.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Move recalculation of inode / vfsmount notification mask under
group->mark_mutex of the mark which was modified. These are the only
places where mask recalculation happens without mark being protected
from detaching from inode / vfsmount which will cause issues with the
following patches.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Printing inode pointers in warnings has dubious value and with future
changes we won't be able to easily get them without either locking or
chances we oops along the way. So just remove inode pointers from the
warning messages.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
show_fdinfo() iterates group's list of marks. All marks found there are
guaranteed to be alive and they stay so until we release
group->mark_mutex. So remove uncecessary tests whether mark is alive.
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Fix up affected files that include this signal functionality via sched.h.
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Add #include <linux/cred.h> dependencies to all .c files rely on sched.h
doing that for them.
Note that even if the count where we need to add extra headers seems high,
it's still a net win, because <linux/sched.h> is included in over
2,200 files ...
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull namespace updates from Eric Biederman:
"There is a lot here. A lot of these changes result in subtle user
visible differences in kernel behavior. I don't expect anything will
care but I will revert/fix things immediately if any regressions show
up.
From Seth Forshee there is a continuation of the work to make the vfs
ready for unpriviled mounts. We had thought the previous changes
prevented the creation of files outside of s_user_ns of a filesystem,
but it turns we missed the O_CREAT path. Ooops.
Pavel Tikhomirov and Oleg Nesterov worked together to fix a long
standing bug in the implemenation of PR_SET_CHILD_SUBREAPER where only
children that are forked after the prctl are considered and not
children forked before the prctl. The only known user of this prctl
systemd forks all children after the prctl. So no userspace
regressions will occur. Holding earlier forked children to the same
rules as later forked children creates a semantic that is sane enough
to allow checkpoing of processes that use this feature.
There is a long delayed change by Nikolay Borisov to limit inotify
instances inside a user namespace.
Michael Kerrisk extends the API for files used to maniuplate
namespaces with two new trivial ioctls to allow discovery of the
hierachy and properties of namespaces.
Konstantin Khlebnikov with the help of Al Viro adds code that when a
network namespace exits purges it's sysctl entries from the dcache. As
in some circumstances this could use a lot of memory.
Vivek Goyal fixed a bug with stacked filesystems where the permissions
on the wrong inode were being checked.
I continue previous work on ptracing across exec. Allowing a file to
be setuid across exec while being ptraced if the tracer has enough
credentials in the user namespace, and if the process has CAP_SETUID
in it's own namespace. Proc files for setuid or otherwise undumpable
executables are now owned by the root in the user namespace of their
mm. Allowing debugging of setuid applications in containers to work
better.
A bug I introduced with permission checking and automount is now
fixed. The big change is to mark the mounts that the kernel initiates
as a result of an automount. This allows the permission checks in sget
to be safely suppressed for this kind of mount. As the permission
check happened when the original filesystem was mounted.
Finally a special case in the mount namespace is removed preventing
unbounded chains in the mount hash table, and making the semantics
simpler which benefits CRIU.
The vfs fix along with related work in ima and evm I believe makes us
ready to finish developing and merge fully unprivileged mounts of the
fuse filesystem. The cleanups of the mount namespace makes discussing
how to fix the worst case complexity of umount. The stacked filesystem
fixes pave the way for adding multiple mappings for the filesystem
uids so that efficient and safer containers can be implemented"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
proc/sysctl: Don't grab i_lock under sysctl_lock.
vfs: Use upper filesystem inode in bprm_fill_uid()
proc/sysctl: prune stale dentries during unregistering
mnt: Tuck mounts under others instead of creating shadow/side mounts.
prctl: propagate has_child_subreaper flag to every descendant
introduce the walk_process_tree() helper
nsfs: Add an ioctl() to return owner UID of a userns
fs: Better permission checking for submounts
exit: fix the setns() && PR_SET_CHILD_SUBREAPER interaction
vfs: open() with O_CREAT should not create inodes with unknown ids
nsfs: Add an ioctl() to return the namespace type
proc: Better ownership of files for non-dumpable tasks in user namespaces
exec: Remove LSM_UNSAFE_PTRACE_CAP
exec: Test the ptracer's saved cred to see if the tracee can gain caps
exec: Don't reset euid and egid when the tracee has CAP_SETUID
inotify: Convert to using per-namespace limits
Pull UDF fixes and cleanups from Jan Kara:
"Several small UDF fixes and cleanups and a small cleanup of fanotify
code"
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
fanotify: simplify the code of fanotify_merge
udf: simplify udf_ioctl()
udf: fix ioctl errors
udf: allow implicit blocksize specification during mount
udf: check partition reference in udf_read_inode()
udf: atomically read inode size
udf: merge module informations in super.c
udf: remove next_epos from udf_update_extent_cache()
udf: Factor out trimming of crtime
udf: remove empty condition
udf: remove unneeded line break
udf: merge bh free
udf: use pointer for kernel_long_ad argument
udf: use __packed instead of __attribute__ ((packed))
udf: Make stat on symlink report symlink length as st_size
fs/udf: make #ifdef UDF_PREALLOCATE unconditional
fs: udf: Replace CURRENT_TIME with current_time()
This patchset converts inotify to using the newly introduced
per-userns sysctl infrastructure.
Currently the inotify instances/watches are being accounted in the
user_struct structure. This means that in setups where multiple
users in unprivileged containers map to the same underlying
real user (i.e. pointing to the same user_struct) the inotify limits
are going to be shared as well, allowing one user(or application) to exhaust
all others limits.
Fix this by switching the inotify sysctls to using the
per-namespace/per-user limits. This will allow the server admin to
set sensible global limits, which can further be tuned inside every
individual user namespace. Additionally, in order to preserve the
sysctl ABI make the existing inotify instances/watches sysctls
modify the values of the initial user namespace.
Signed-off-by: Nikolay Borisov <n.borisov.lkml@gmail.com>
Acked-by: Jan Kara <jack@suse.cz>
Acked-by: Serge Hallyn <serge@hallyn.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Pull audit fixes from Paul Moore:
"Two small fixes relating to audit's use of fsnotify.
The first patch plugs a leak and the second fixes some lock
shenanigans. The patches are small and I banged on this for an
afternoon with our testsuite and didn't see anything odd"
* 'stable-4.10' of git://git.infradead.org/users/pcmoore/audit:
audit: Fix sleep in atomic
fsnotify: Remove fsnotify_duplicate_mark()
There are only two calls sites of fsnotify_duplicate_mark(). Those are
in kernel/audit_tree.c and both are bogus. Vfsmount pointer is unused
for audit tree, inode pointer and group gets set in
fsnotify_add_mark_locked() later anyway, mask and free_mark are already
set in alloc_chunk(). In fact, calling fsnotify_duplicate_mark() is
actively harmful because following fsnotify_add_mark_locked() will leak
group reference by overwriting the group pointer. So just remove the two
calls to fsnotify_duplicate_mark() and the function.
Signed-off-by: Jan Kara <jack@suse.cz>
[PM: line wrapping to fit in 80 chars]
Signed-off-by: Paul Moore <paul@paul-moore.com>
Pull quota, fsnotify and ext2 updates from Jan Kara:
"Changes to locking of some quota operations from dedicated quota mutex
to s_umount semaphore, a fsnotify fix and a simple ext2 fix"
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
quota: Fix bogus warning in dquot_disable()
fsnotify: Fix possible use-after-free in inode iteration on umount
ext2: reject inodes with negative size
quota: Remove dqonoff_mutex
ocfs2: Use s_umount for quota recovery protection
quota: Remove dqonoff_mutex from dquot_scan_active()
ocfs2: Protect periodic quota syncing with s_umount semaphore
quota: Use s_umount protection for quota operations
quota: Hold s_umount in exclusive mode when enabling / disabling quotas
fs: Provide function to get superblock with exclusive s_umount
fsnotify_unmount_inodes() plays complex tricks to pin next inode in the
sb->s_inodes list when iterating over all inodes. Furthermore the code has a
bug that if the current inode is the last on i_sb_list that does not have e.g.
I_FREEING set, then we leave next_i pointing to inode which may get removed
from the i_sb_list once we drop s_inode_list_lock thus resulting in
use-after-free issues (usually manifesting as infinite looping in
fsnotify_unmount_inodes()).
Fix the problem by keeping current inode pinned somewhat longer. Then we can
make the code much simpler and standard.
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Amir Goldstein