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Alexei Starovoitov 449325b52b umh: introduce fork_usermode_blob() helper 
Introduce helper:
int fork_usermode_blob(void *data, size_t len, struct umh_info *info);
struct umh_info {
       struct file *pipe_to_umh;
       struct file *pipe_from_umh;
       pid_t pid;
};

that GPLed kernel modules (signed or unsigned) can use it to execute part
of its own data as swappable user mode process.

The kernel will do:
- allocate a unique file in tmpfs
- populate that file with [data, data + len] bytes
- user-mode-helper code will do_execve that file and, before the process
  starts, the kernel will create two unix pipes for bidirectional
  communication between kernel module and umh
- close tmpfs file, effectively deleting it
- the fork_usermode_blob will return zero on success and populate
  'struct umh_info' with two unix pipes and the pid of the user process

As the first step in the development of the bpfilter project
the fork_usermode_blob() helper is introduced to allow user mode code
to be invoked from a kernel module. The idea is that user mode code plus
normal kernel module code are built as part of the kernel build
and installed as traditional kernel module into distro specified location,
such that from a distribution point of view, there is
no difference between regular kernel modules and kernel modules + umh code.
Such modules can be signed, modprobed, rmmod, etc. The use of this new helper
by a kernel module doesn't make it any special from kernel and user space
tooling point of view.

Such approach enables kernel to delegate functionality traditionally done
by the kernel modules into the user space processes (either root or !root) and
reduces security attack surface of the new code. The buggy umh code would crash
the user process, but not the kernel. Another advantage is that umh code
of the kernel module can be debugged and tested out of user space
(e.g. opening the possibility to run clang sanitizers, fuzzers or
user space test suites on the umh code).
In case of the bpfilter project such architecture allows complex control plane
to be done in the user space while bpf based data plane stays in the kernel.

Since umh can crash, can be oom-ed by the kernel, killed by the admin,
the kernel module that uses them (like bpfilter) needs to manage life
time of umh on its own via two unix pipes and the pid of umh.

The exit code of such kernel module should kill the umh it started,
so that rmmod of the kernel module will cleanup the corresponding umh.
Just like if the kernel module does kmalloc() it should kfree() it
in the exit code.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
 		2018-05-23 13:23:39 -04:00
..
9p fscache development 2018-04-07 09:08:24 -07:00
adfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
affs iversion: Rename make inode_cmp_iversion{+raw} to inode_eq_iversion{+raw} 2018-02-01 08:15:25 -05:00
afs afs: Fix the non-encryption of calls 2018-05-14 15:15:19 +01:00
autofs4 autofs: mount point create should honour passed in mode 2018-04-20 17:18:35 -07:00
befs befs: Define usercopy region in befs_inode_cache slab cache 2018-01-15 12:07:54 -08:00
bfs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
btrfs for-4.17-rc5-tag 2018-05-20 12:04:27 -07:00
cachefiles fscache: Pass object size in rather than calling back for it 2018-04-06 14:05:14 +01:00
ceph ceph: fix iov_iter issues in ceph_direct_read_write() 2018-05-10 10:15:12 +02:00
cifs smb3: directory sync should not return an error 2018-05-10 19:21:14 -05:00
coda vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
configfs configfs: make ci_type field, some pointers and function arguments const 2017-10-19 16:15:16 +02:00
cramfs cramfs: better MTD dependency expression 2018-02-08 11:37:31 -08:00
crypto fscrypt: fix build with pre-4.6 gcc versions 2018-02-01 10:51:18 -05:00
debugfs debugfs_lookup(): switch to lookup_one_len_unlocked() 2018-03-29 15:07:47 -04:00
devpts devpts: comment devpts_mntget() 2018-03-14 13:31:23 +01:00
dlm net: make getname() functions return length rather than use int* parameter 2018-02-12 14:15:04 -05:00
ecryptfs eCryptfs: don't pass up plaintext names when using filename encryption 2018-04-16 18:51:22 +00:00
efivarfs efivarfs: Limit the rate for non-root to read files 2018-02-22 10:21:02 -08:00
efs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
exofs iversion.h related cleanup for v4.16 2018-02-07 14:25:22 -08:00
exportfs ovl: do not try to reconnect a disconnected origin dentry 2018-04-12 12:04:49 +02:00
ext2 \n 2018-04-20 09:01:26 -07:00
ext4 Fix misc. bugs and a regression for ext4. 2018-04-28 20:07:21 -07:00
f2fs page cache: use xa_lock 2018-04-11 10:28:39 -07:00
fat iversion: Rename make inode_cmp_iversion{+raw} to inode_eq_iversion{+raw} 2018-02-01 08:15:25 -05:00
freevxfs vxfs: Define usercopy region in vxfs_inode slab cache 2018-01-15 12:07:57 -08:00
fscache fscache: use appropriate radix tree accessors 2018-04-11 10:28:39 -07:00
fuse fuse: define the filesystem as untrusted 2018-03-23 06:31:37 -04:00
gfs2 GFS2: Minor improvements to comments and documentation 2018-04-12 10:07:51 -07:00
hfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
hfsplus hfsplus: stop workqueue when fill_super() failed 2018-05-18 17:17:12 -07:00
hostfs hostfs: rename do_rmdir() to hostfs_do_rmdir() 2018-04-02 20:15:53 +02:00
hpfs hpfs: don't bother with the i_version counter or f_version 2017-12-10 12:58:18 -08:00
hugetlbfs hugetlbfs: fix bug in pgoff overflow checking 2018-04-05 21:36:21 -07:00
isofs isofs: fix potential memory leak in mount option parsing 2018-04-16 09:47:41 +02:00
jbd2 ext4: set h_journal if there is a failure starting a reserved handle 2018-04-18 11:49:31 -04:00
jffs2 jffs2_kill_sb(): deal with failed allocations 2018-04-15 23:49:05 -04:00
jfs Currently, hardened usercopy performs dynamic bounds checking on slab 2018-02-03 16:25:42 -08:00
kernfs vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
lockd net: Drop pernet_operations::async 2018-03-27 13:18:09 -04:00
minix treewide: simplify Kconfig dependencies for removed archs 2018-03-26 15:55:57 +02:00
nfs NFS client updates for Linux 4.17 2018-04-12 12:55:50 -07:00
nfs_common net: Drop pernet_operations::async 2018-03-27 13:18:09 -04:00
nfsd nfsd: fix incorrect umasks 2018-04-03 16:27:08 -04:00
nilfs2 page cache: use xa_lock 2018-04-11 10:28:39 -07:00
nls License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
notify fsnotify: fix ignore mask logic in send_to_group() 2018-04-13 15:52:49 +02:00
ntfs ntfs: fix bogus __mark_inode_dirty(I_DIRTY_SYNC | I_DIRTY_DATASYNC) call 2018-03-28 01:39:02 -04:00
ocfs2 ocfs2: take inode cluster lock before moving reflinked inode from orphan dir 2018-05-11 17:28:45 -07:00
omfs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
openpromfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
orangefs orangefs_kill_sb(): deal with allocation failures 2018-04-15 23:49:12 -04:00
overlayfs ovl: add support for "xino" mount and config options 2018-04-12 12:04:50 +02:00
proc Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2018-05-21 16:01:54 -04:00
pstore pstore: fix crypto dependencies without compression 2018-04-06 15:45:33 -07:00
qnx4 Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
qnx6 Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
quota fs: quota: Replace GFP_ATOMIC with GFP_KERNEL in dquot_init 2018-04-09 17:48:54 +02:00
ramfs
…
reiserfs fs/reiserfs/journal.c: add missing resierfs_warning() arg 2018-04-11 10:28:36 -07:00
romfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
squashfs Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
sysfs sysfs: symlink: export sysfs_create_link_nowarn() 2018-03-19 21:14:26 -04:00
sysv Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
tracefs
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ubifs This pull request contains updates for both UBI and UBIFS: 2018-04-11 16:39:34 -07:00
udf udf: Fix leak of UTF-16 surrogates into encoded strings 2018-04-18 16:34:55 +02:00
ufs iversion.h related cleanup for v4.16 2018-02-07 14:25:22 -08:00
xfs xfs: cap the length of deduplication requests 2018-05-02 09:21:33 -07:00
Kconfig libnvdimm for 4.16 2018-02-06 10:41:33 -08:00
Kconfig.binfmt treewide: simplify Kconfig dependencies for removed archs 2018-03-26 15:55:57 +02:00
Makefile split d_path() and friends into a separate file 2018-03-29 15:07:46 -04:00
aio.c fs/aio: Use rcu_work instead of explicit rcu and work item 2018-03-19 10:12:03 -07:00
anon_inodes.c
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attr.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
bad_inode.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
binfmt_aout.c exec: introduce finalize_exec() before start_thread() 2018-04-11 10:28:37 -07:00
binfmt_elf.c fs, elf: don't complain MAP_FIXED_NOREPLACE unless -EEXIST error 2018-04-20 17:18:36 -07:00
binfmt_elf_fdpic.c exec: introduce finalize_exec() before start_thread() 2018-04-11 10:28:37 -07:00
binfmt_em86.c
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binfmt_flat.c exec: introduce finalize_exec() before start_thread() 2018-04-11 10:28:37 -07:00
binfmt_misc.c fs: add ksys_close() wrapper; remove in-kernel calls to sys_close() 2018-04-02 20:16:00 +02:00
binfmt_script.c
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block_dev.c libnvdimm for 4.17 2018-04-10 10:25:57 -07:00
buffer.c Merge branch 'work.thaw' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-04-12 12:28:32 -07:00
char_dev.c block, char_dev: Use correct format specifier for unsigned ints 2018-03-15 17:59:24 +01:00
compat.c
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compat_binfmt_elf.c
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compat_ioctl.c fs: compat_ioctl: add new DVB demux ioctls 2017-12-28 11:17:29 -05:00
coredump.c Merge branch 'misc.compat' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2017-11-17 11:54:55 -08:00
d_path.c split d_path() and friends into a separate file 2018-03-29 15:07:46 -04:00
dax.c page cache: use xa_lock 2018-04-11 10:28:39 -07:00
dcache.c fs/dcache.c: add cond_resched() in shrink_dentry_list() 2018-04-11 10:28:38 -07:00
dcookies.c fs: add do_lookup_dcookie() helper; remove in-kernel call to syscall 2018-04-02 20:15:39 +02:00
direct-io.c Merge branch 'akpm' (patches from Andrew) 2018-04-06 14:19:26 -07:00
drop_caches.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
eventfd.c fs: add do_eventfd() helper; remove internal call to sys_eventfd() 2018-04-02 20:15:39 +02:00
eventpoll.c fs: add do_epoll_*() helpers; remove internal calls to sys_epoll_*() 2018-04-02 20:15:37 +02:00
exec.c umh: introduce fork_usermode_blob() helper 2018-05-23 13:23:39 -04:00
fcntl.c fs: add do_compat_fcntl64() helper; remove in-kernel call to compat syscall 2018-04-02 20:15:42 +02:00
fhandle.c vfs: Copy struct mount.mnt_id to userspace using put_user() 2018-01-15 12:07:51 -08:00
file.c fs: add ksys_close() wrapper; remove in-kernel calls to sys_close() 2018-04-02 20:16:00 +02:00
file_table.c vfs: remove unused hardirq.h 2017-12-07 14:23:30 -05:00
filesystems.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs-writeback.c bdi: Fix oops in wb_workfn() 2018-05-03 16:11:37 -06:00
fs_pin.c Merge branch 'linus' into locking/core, to resolve conflicts 2017-11-07 10:32:44 +01:00
fs_struct.c
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inode.c page cache: use xa_lock 2018-04-11 10:28:39 -07:00
internal.h Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-04-06 11:07:08 -07:00
ioctl.c fs: add ksys_ioctl() helper; remove in-kernel calls to sys_ioctl() 2018-04-02 20:16:03 +02:00
iomap.c iomap: warn on zero-length mappings 2018-01-29 07:27:24 -08:00
libfs.c fs, dax: prepare for dax-specific address_space_operations 2018-03-30 11:34:55 -07:00
locks.c treewide: Align function definition open/close braces 2018-03-26 11:13:09 +02:00
mbcache.c mbcache: make sure c_entry_count is not decremented past zero 2018-01-09 23:57:52 -05:00
mount.h License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
mpage.c License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
namei.c Merge branch 'work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-04-09 12:48:05 -07:00
namespace.c vfs: Undo an overly zealous MS_RDONLY -> SB_RDONLY conversion 2018-04-20 09:59:33 -07:00
no-block.c
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nsfs.c net: Export open_related_ns() 2018-02-15 15:34:42 -05:00
open.c Merge branch 'work.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2018-04-06 11:07:08 -07:00
pipe.c fs: add do_pipe2() helper; remove internal call to sys_pipe2() 2018-04-02 20:15:35 +02:00
pnode.c
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pnode.h
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posix_acl.c posix_acl: convert posix_acl.a_refcount from atomic_t to refcount_t 2018-01-02 19:27:28 -08:00
proc_namespace.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
read_write.c fs: add ksys_p{read,write}64() helpers; remove in-kernel calls to syscalls 2018-04-02 20:16:09 +02:00
readdir.c fs: add ksys_getdents64() helper; remove in-kernel calls to sys_getdents64() 2018-04-02 20:16:02 +02:00
select.c fs: add do_compat_select() helper; remove in-kernel call to compat syscall 2018-04-02 20:15:42 +02:00
seq_file.c seq_file: account everything to kmemcg 2018-04-11 10:28:36 -07:00
signalfd.c fs: add do_compat_signalfd4() helper; remove in-kernel call to compat syscall 2018-04-02 20:15:43 +02:00
splice.c fs: add do_vmsplice() helper; remove in-kernel call to syscall 2018-04-02 20:15:40 +02:00
stack.c
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stat.c fs: add do_readlinkat() helper; remove internal call to sys_readlinkat() 2018-04-02 20:15:34 +02:00
statfs.c Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
super.c mm,vmscan: Allow preallocating memory for register_shrinker(). 2018-04-16 02:06:47 -04:00
sync.c Changes for this release: 2018-04-04 12:44:02 -07:00
timerfd.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
userfaultfd.c vfs: do bulk POLL* -> EPOLL* replacement 2018-02-11 14:34:03 -08:00
utimes.c fs: add do_compat_futimesat() helper; remove in-kernel call to compat syscall 2018-04-02 20:15:44 +02:00
xattr.c
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