commit 22e111ed6c upstream.
We should never lock two subdirectories without having taken
->s_vfs_rename_mutex; inode pointer order or not, the "order" proposed
in 28eceeda13 "fs: Lock moved directories" is not transitive, with
the usual consequences.
The rationale for locking renamed subdirectory in all cases was
the possibility of race between rename modifying .. in a subdirectory to
reflect the new parent and another thread modifying the same subdirectory.
For a lot of filesystems that's not a problem, but for some it can lead
to trouble (e.g. the case when short directory contents is kept in the
inode, but creating a file in it might push it across the size limit
and copy its contents into separate data block(s)).
However, we need that only in case when the parent does change -
otherwise ->rename() doesn't need to do anything with .. entry in the
first place. Some instances are lazy and do a tautological update anyway,
but it's really not hard to avoid.
Amended locking rules for rename():
find the parent(s) of source and target
if source and target have the same parent
lock the common parent
else
lock ->s_vfs_rename_mutex
lock both parents, in ancestor-first order; if neither
is an ancestor of another, lock the parent of source
first.
find the source and target.
if source and target have the same parent
if operation is an overwriting rename of a subdirectory
lock the target subdirectory
else
if source is a subdirectory
lock the source
if target is a subdirectory
lock the target
lock non-directories involved, in inode pointer order if both
source and target are such.
That way we are guaranteed that parents are locked (for obvious reasons),
that any renamed non-directory is locked (nfsd relies upon that),
that any victim is locked (emptiness check needs that, among other things)
and subdirectory that changes parent is locked (needed to protect the update
of .. entries). We are also guaranteed that any operation locking more
than one directory either takes ->s_vfs_rename_mutex or locks a parent
followed by its child.
Cc: stable@vger.kernel.org
Fixes: 28eceeda13 "fs: Lock moved directories"
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 74d7970feb ]
Al pointed out that ksmbd has racy issue from using ->d_parent and ->d_name
in ksmbd_vfs_unlink and smb2_vfs_rename(). and use new lock_rename_child()
to lock stable parent while underlying rename racy.
Introduce vfs_path_parent_lookup helper to avoid out of share access and
export vfs functions like the following ones to use
vfs_path_parent_lookup().
- rename __lookup_hash() to lookup_one_qstr_excl().
- export lookup_one_qstr_excl().
- export getname_kernel() and putname().
vfs_path_parent_lookup() is used for parent lookup of destination file
using absolute pathname given from FILE_RENAME_INFORMATION request.
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 9bc37e0482 ]
Pass the dentry of a source file and the dentry of a destination directory
to lock parent inodes for rename. As soon as this function returns,
->d_parent of the source file dentry is stable and inodes are properly
locked for calling vfs-rename. This helper is needed for ksmbd server.
rename request of SMB protocol has to rename an opened file, no matter
which directory it's in.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 03adc61eda upstream.
An io_uring openat operation can update an audit reference count
from multiple threads resulting in the call trace below.
A call to io_uring_submit() with a single openat op with a flag of
IOSQE_ASYNC results in the following reference count updates.
These first part of the system call performs two increments that do not race.
do_syscall_64()
__do_sys_io_uring_enter()
io_submit_sqes()
io_openat_prep()
__io_openat_prep()
getname()
getname_flags() /* update 1 (increment) */
__audit_getname() /* update 2 (increment) */
The openat op is queued to an io_uring worker thread which starts the
opportunity for a race. The system call exit performs one decrement.
do_syscall_64()
syscall_exit_to_user_mode()
syscall_exit_to_user_mode_prepare()
__audit_syscall_exit()
audit_reset_context()
putname() /* update 3 (decrement) */
The io_uring worker thread performs one increment and two decrements.
These updates can race with the system call decrement.
io_wqe_worker()
io_worker_handle_work()
io_wq_submit_work()
io_issue_sqe()
io_openat()
io_openat2()
do_filp_open()
path_openat()
__audit_inode() /* update 4 (increment) */
putname() /* update 5 (decrement) */
__audit_uring_exit()
audit_reset_context()
putname() /* update 6 (decrement) */
The fix is to change the refcnt member of struct audit_names
from int to atomic_t.
kernel BUG at fs/namei.c:262!
Call Trace:
...
? putname+0x68/0x70
audit_reset_context.part.0.constprop.0+0xe1/0x300
__audit_uring_exit+0xda/0x1c0
io_issue_sqe+0x1f3/0x450
? lock_timer_base+0x3b/0xd0
io_wq_submit_work+0x8d/0x2b0
? __try_to_del_timer_sync+0x67/0xa0
io_worker_handle_work+0x17c/0x2b0
io_wqe_worker+0x10a/0x350
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/lkml/MW2PR2101MB1033FFF044A258F84AEAA584F1C9A@MW2PR2101MB1033.namprd21.prod.outlook.com/
Fixes: 5bd2182d58 ("audit,io_uring,io-wq: add some basic audit support to io_uring")
Signed-off-by: Dan Clash <daclash@linux.microsoft.com>
Link: https://lore.kernel.org/r/20231012215518.GA4048@linuxonhyperv3.guj3yctzbm1etfxqx2vob5hsef.xx.internal.cloudapp.net
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 0d5a4f8f77 ]
The d_hash_and_lookup() function returns error pointers or NULL.
Most incorrect error checks were fixed, but the one in int path_pts()
was forgotten.
Fixes: eedf265aa0 ("devpts: Make each mount of devpts an independent filesystem.")
Signed-off-by: Wang Ming <machel@vivo.com>
Message-Id: <20230713120555.7025-1-machel@vivo.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
commit 66d8fc0539 upstream.
The @source inode must be valid. It is even checked via IS_SWAPFILE()
above making it pretty clear. So no need to check it when we unlock.
What doesn't need to exist is the @target inode. The lock_two_inodes()
helper currently swaps the @inode1 and @inode2 arguments if @inode1 is
NULL to have consistent lock class usage. However, we know that at least
for vfs_rename() that @inode1 is @source and thus is never NULL as per
above. We also know that @source is a different inode than @target as
that is checked right at the beginning of vfs_rename(). So we know that
@source is valid and locked and that @target is locked. So drop the
check whether @source is non-NULL.
Fixes: 28eceeda13 ("fs: Lock moved directories")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/r/202307030026.9sE2pk2x-lkp@intel.com
Message-Id: <20230703-vfs-rename-source-v1-1-37eebb29b65b@kernel.org>
[brauner: use commit message from patch I sent concurrently]
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit 28eceeda13 upstream.
When a directory is moved to a different directory, some filesystems
(udf, ext4, ocfs2, f2fs, and likely gfs2, reiserfs, and others) need to
update their pointer to the parent and this must not race with other
operations on the directory. Lock the directories when they are moved.
Although not all filesystems need this locking, we perform it in
vfs_rename() because getting the lock ordering right is really difficult
and we don't want to expose these locking details to filesystems.
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230601105830.13168-5-jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit f23ce75718 upstream.
Currently the locking order of inode locks for directories that are not
in ancestor relationship is not defined because all operations that
needed to lock two directories like this were serialized by
sb->s_vfs_rename_mutex. However some filesystems need to lock two
subdirectories for RENAME_EXCHANGE operations and for this we need the
locking order established even for two tree-unrelated directories.
Provide a helper function lock_two_inodes() that establishes lock
ordering for any two inodes and use it in lock_two_directories().
CC: stable@vger.kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Message-Id: <20230601105830.13168-4-jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
If O_EXCL is *not* specified, then linkat() can be
used to link the temporary file into the filesystem.
If O_EXCL is specified then linkat() should fail (-1).
After commit 863f144f12 ("vfs: open inside ->tmpfile()")
the O_EXCL flag is no longer honored by the vfs layer for
tmpfile, which means the file can be linked even if O_EXCL
flag is specified, which is a change in behaviour for
userspace!
The open flags was previously passed as a parameter, so it
was uneffected by the changes to file->f_flags caused by
finish_open(). This patch fixes the issue by storing
file->f_flags in a local variable so the O_EXCL test
logic is restored.
This regression was detected by Android CTS Bionic fcntl()
tests running on android-mainline [1].
[1] https://android.googlesource.com/platform/bionic/+/
refs/heads/master/tests/fcntl_test.cpp#352
Fixes: 863f144f12 ("vfs: open inside ->tmpfile()")
Acked-by: Miklos Szeredi <mszeredi@redhat.com>
Tested-by: Will McVicker <willmcvicker@google.com>
Signed-off-by: Peter Griffin <peter.griffin@linaro.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-----BEGIN PGP SIGNATURE-----
iHUEABYIAB0WIQQqUNBr3gm4hGXdBJlZ7Krx/gZQ6wUCY0DP2AAKCRBZ7Krx/gZQ
6/+qAQCEGQWpcC5MB17zylaX7gqzhgAsDrwtpevlno3aIv/1pQD/YWr/E8tf7WTW
ERXRXMRx1cAzBJhUhVgIY+3ANfU2Rg4=
=cko4
-----END PGP SIGNATURE-----
Merge tag 'pull-tmpfile' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs tmpfile updates from Al Viro:
"Miklos' ->tmpfile() signature change; pass an unopened struct file to
it, let it open the damn thing. Allows to add tmpfile support to FUSE"
* tag 'pull-tmpfile' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
fuse: implement ->tmpfile()
vfs: open inside ->tmpfile()
vfs: move open right after ->tmpfile()
vfs: make vfs_tmpfile() static
ovl: use vfs_tmpfile_open() helper
cachefiles: use vfs_tmpfile_open() helper
cachefiles: only pass inode to *mark_inode_inuse() helpers
cachefiles: tmpfile error handling cleanup
hugetlbfs: cleanup mknod and tmpfile
vfs: add vfs_tmpfile_open() helper
linux-next for a couple of months without, to my knowledge, any negative
reports (or any positive ones, come to that).
- Also the Maple Tree from Liam R. Howlett. An overlapping range-based
tree for vmas. It it apparently slight more efficient in its own right,
but is mainly targeted at enabling work to reduce mmap_lock contention.
Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.
Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
(https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com).
This has yet to be addressed due to Liam's unfortunately timed
vacation. He is now back and we'll get this fixed up.
- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down to
the single bit level.
KMSAN keeps finding bugs. New ones, as well as the legacy ones.
- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.
- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to support
file/shmem-backed pages.
- userfaultfd updates from Axel Rasmussen
- zsmalloc cleanups from Alexey Romanov
- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and memory-failure
- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.
- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.
- memcg cleanups from Kairui Song.
- memcg fixes and cleanups from Johannes Weiner.
- Vishal Moola provides more folio conversions
- Zhang Yi removed ll_rw_block() :(
- migration enhancements from Peter Xu
- migration error-path bugfixes from Huang Ying
- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.
- vma merging improvements from Jakub Matěn.
- NUMA hinting cleanups from David Hildenbrand.
- xu xin added aditional userspace visibility into KSM merging activity.
- THP & KSM code consolidation from Qi Zheng.
- more folio work from Matthew Wilcox.
- KASAN updates from Andrey Konovalov.
- DAMON cleanups from Kaixu Xia.
- DAMON work from SeongJae Park: fixes, cleanups.
- hugetlb sysfs cleanups from Muchun Song.
- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.
-----BEGIN PGP SIGNATURE-----
iHUEABYKAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCY0HaPgAKCRDdBJ7gKXxA
joPjAQDZ5LlRCMWZ1oxLP2NOTp6nm63q9PWcGnmY50FjD/dNlwEAnx7OejCLWGWf
bbTuk6U2+TKgJa4X7+pbbejeoqnt5QU=
=xfWx
-----END PGP SIGNATURE-----
Merge tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- Yu Zhao's Multi-Gen LRU patches are here. They've been under test in
linux-next for a couple of months without, to my knowledge, any
negative reports (or any positive ones, come to that).
- Also the Maple Tree from Liam Howlett. An overlapping range-based
tree for vmas. It it apparently slightly more efficient in its own
right, but is mainly targeted at enabling work to reduce mmap_lock
contention.
Liam has identified a number of other tree users in the kernel which
could be beneficially onverted to mapletrees.
Yu Zhao has identified a hard-to-hit but "easy to fix" lockdep splat
at [1]. This has yet to be addressed due to Liam's unfortunately
timed vacation. He is now back and we'll get this fixed up.
- Dmitry Vyukov introduces KMSAN: the Kernel Memory Sanitizer. It uses
clang-generated instrumentation to detect used-unintialized bugs down
to the single bit level.
KMSAN keeps finding bugs. New ones, as well as the legacy ones.
- Yang Shi adds a userspace mechanism (madvise) to induce a collapse of
memory into THPs.
- Zach O'Keefe has expanded Yang Shi's madvise(MADV_COLLAPSE) to
support file/shmem-backed pages.
- userfaultfd updates from Axel Rasmussen
- zsmalloc cleanups from Alexey Romanov
- cleanups from Miaohe Lin: vmscan, hugetlb_cgroup, hugetlb and
memory-failure
- Huang Ying adds enhancements to NUMA balancing memory tiering mode's
page promotion, with a new way of detecting hot pages.
- memcg updates from Shakeel Butt: charging optimizations and reduced
memory consumption.
- memcg cleanups from Kairui Song.
- memcg fixes and cleanups from Johannes Weiner.
- Vishal Moola provides more folio conversions
- Zhang Yi removed ll_rw_block() :(
- migration enhancements from Peter Xu
- migration error-path bugfixes from Huang Ying
- Aneesh Kumar added ability for a device driver to alter the memory
tiering promotion paths. For optimizations by PMEM drivers, DRM
drivers, etc.
- vma merging improvements from Jakub Matěn.
- NUMA hinting cleanups from David Hildenbrand.
- xu xin added aditional userspace visibility into KSM merging
activity.
- THP & KSM code consolidation from Qi Zheng.
- more folio work from Matthew Wilcox.
- KASAN updates from Andrey Konovalov.
- DAMON cleanups from Kaixu Xia.
- DAMON work from SeongJae Park: fixes, cleanups.
- hugetlb sysfs cleanups from Muchun Song.
- Mike Kravetz fixes locking issues in hugetlbfs and in hugetlb core.
Link: https://lkml.kernel.org/r/CAOUHufZabH85CeUN-MEMgL8gJGzJEWUrkiM58JkTbBhh-jew0Q@mail.gmail.com [1]
* tag 'mm-stable-2022-10-08' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (555 commits)
hugetlb: allocate vma lock for all sharable vmas
hugetlb: take hugetlb vma_lock when clearing vma_lock->vma pointer
hugetlb: fix vma lock handling during split vma and range unmapping
mglru: mm/vmscan.c: fix imprecise comments
mm/mglru: don't sync disk for each aging cycle
mm: memcontrol: drop dead CONFIG_MEMCG_SWAP config symbol
mm: memcontrol: use do_memsw_account() in a few more places
mm: memcontrol: deprecate swapaccounting=0 mode
mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled
mm/secretmem: remove reduntant return value
mm/hugetlb: add available_huge_pages() func
mm: remove unused inline functions from include/linux/mm_inline.h
selftests/vm: add selftest for MADV_COLLAPSE of uffd-minor memory
selftests/vm: add file/shmem MADV_COLLAPSE selftest for cleared pmd
selftests/vm: add thp collapse shmem testing
selftests/vm: add thp collapse file and tmpfs testing
selftests/vm: modularize thp collapse memory operations
selftests/vm: dedup THP helpers
mm/khugepaged: add tracepoint to hpage_collapse_scan_file()
mm/madvise: add file and shmem support to MADV_COLLAPSE
...
Functions implementing the a_ops->write_end() interface accept the `void
*fsdata` parameter that is supposed to be initialized by the corresponding
a_ops->write_begin() (which accepts `void **fsdata`).
However not all a_ops->write_begin() implementations initialize `fsdata`
unconditionally, so it may get passed uninitialized to a_ops->write_end(),
resulting in undefined behavior.
Fix this by initializing fsdata with NULL before the call to
write_begin(), rather than doing so in all possible a_ops implementations.
This patch covers only the following cases found by running x86 KMSAN
under syzkaller:
- generic_perform_write()
- cont_expand_zero() and generic_cont_expand_simple()
- page_symlink()
Other cases of passing uninitialized fsdata may persist in the codebase.
Link: https://lkml.kernel.org/r/20220915150417.722975-43-glider@google.com
Signed-off-by: Alexander Potapenko <glider@google.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Konovalov <andreyknvl@google.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Eric Biggers <ebiggers@google.com>
Cc: Eric Biggers <ebiggers@kernel.org>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Ilya Leoshkevich <iii@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Marco Elver <elver@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael S. Tsirkin <mst@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Vegard Nossum <vegard.nossum@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This is in preparation for adding tmpfile support to fuse, which requires
that the tmpfile creation and opening are done as a single operation.
Replace the 'struct dentry *' argument of i_op->tmpfile with
'struct file *'.
Call finish_open_simple() as the last thing in ->tmpfile() instances (may
be omitted in the error case).
Change d_tmpfile() argument to 'struct file *' as well to make callers more
readable.
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Create a helper finish_open_simple() that opens the file with the original
dentry. Handle the error case here as well to simplify callers.
Call this helper right after ->tmpfile() is called.
Next patch will change the tmpfile API and move this call into tmpfile
instances.
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
No callers outside of fs/namei.c anymore.
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
This helper unifies tmpfile creation with opening.
Existing vfs_tmpfile() callers outside of fs/namei.c will be converted to
using this helper. There are two such callers: cachefile and overlayfs.
The cachefiles code currently uses the open_with_fake_path() helper to open
the tmpfile, presumably to disable accounting of the open file. Overlayfs
uses tmpfile for copy_up, which means these struct file instances will be
short lived, hence it doesn't really matter if they are accounted or not.
Disable accounting in this helper too, which should be okay for both
callers.
Add MAY_OPEN permission checking for consistency. Like for create(2)
read/write permissions are not checked.
Reviewed-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
-----BEGIN PGP SIGNATURE-----
iHQEABYKAB0WIQRAhzRXHqcMeLMyaSiRxhvAZXjcogUCYvIYIgAKCRCRxhvAZXjc
omE8AQDAZG2YjNJfMnUUaaWYO3+zTaHlQp7OQkQTXIHfcfViXQD4vPt3Wxh3rrF+
J8fwNcWmXhSNei8HP6cA06QmSajnDQ==
=GF9/
-----END PGP SIGNATURE-----
Merge tag 'fs.setgid.v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull setgid updates from Christian Brauner:
"This contains the work to move setgid stripping out of individual
filesystems and into the VFS itself.
Creating files that have both the S_IXGRP and S_ISGID bit raised in
directories that themselves have the S_ISGID bit set requires
additional privileges to avoid security issues.
When a filesystem creates a new inode it needs to take care that the
caller is either in the group of the newly created inode or they have
CAP_FSETID in their current user namespace and are privileged over the
parent directory of the new inode. If any of these two conditions is
true then the S_ISGID bit can be raised for an S_IXGRP file and if not
it needs to be stripped.
However, there are several key issues with the current implementation:
- S_ISGID stripping logic is entangled with umask stripping.
For example, if the umask removes the S_IXGRP bit from the file
about to be created then the S_ISGID bit will be kept.
The inode_init_owner() helper is responsible for S_ISGID stripping
and is called before posix_acl_create(). So we can end up with two
different orderings:
1. FS without POSIX ACL support
First strip umask then strip S_ISGID in inode_init_owner().
In other words, if a filesystem doesn't support or enable POSIX
ACLs then umask stripping is done directly in the vfs before
calling into the filesystem:
2. FS with POSIX ACL support
First strip S_ISGID in inode_init_owner() then strip umask in
posix_acl_create().
In other words, if the filesystem does support POSIX ACLs then
unmask stripping may be done in the filesystem itself when
calling posix_acl_create().
Note that technically filesystems are free to impose their own
ordering between posix_acl_create() and inode_init_owner() meaning
that there's additional ordering issues that influence S_ISGID
inheritance.
(Note that the commit message of commit 1639a49ccd ("fs: move
S_ISGID stripping into the vfs_*() helpers") gets the ordering
between inode_init_owner() and posix_acl_create() the wrong way
around. I realized this too late.)
- Filesystems that don't rely on inode_init_owner() don't get S_ISGID
stripping logic.
While that may be intentional (e.g. network filesystems might just
defer setgid stripping to a server) it is often just a security
issue.
Note that mandating the use of inode_init_owner() was proposed as
an alternative solution but that wouldn't fix the ordering issues
and there are examples such as afs where the use of
inode_init_owner() isn't possible.
In any case, we should also try the cleaner and generalized
solution first before resorting to this approach.
- We still have S_ISGID inheritance bugs years after the initial
round of S_ISGID inheritance fixes:
e014f37db1 ("xfs: use setattr_copy to set vfs inode attributes")
01ea173e10 ("xfs: fix up non-directory creation in SGID directories")
fd84bfdddd ("ceph: fix up non-directory creation in SGID directories")
All of this led us to conclude that the current state is too messy.
While we won't be able to make it completely clean as
posix_acl_create() is still a filesystem specific call we can improve
the S_SIGD stripping situation quite a bit by hoisting it out of
inode_init_owner() and into the respective vfs creation operations.
The obvious advantage is that we don't need to rely on individual
filesystems getting S_ISGID stripping right and instead can
standardize the ordering between S_ISGID and umask stripping directly
in the VFS.
A few short implementation notes:
- The stripping logic needs to happen in vfs_*() helpers for the sake
of stacking filesystems such as overlayfs that rely on these
helpers taking care of S_ISGID stripping.
- Security hooks have never seen the mode as it is ultimately seen by
the filesystem because of the ordering issue we mentioned. Nothing
is changed for them. We simply continue to strip the umask before
passing the mode down to the security hooks.
- The following filesystems use inode_init_owner() and thus relied on
S_ISGID stripping: spufs, 9p, bfs, btrfs, ext2, ext4, f2fs,
hfsplus, hugetlbfs, jfs, minix, nilfs2, ntfs3, ocfs2, omfs,
overlayfs, ramfs, reiserfs, sysv, ubifs, udf, ufs, xfs, zonefs,
bpf, tmpfs.
We've audited all callchains as best as we could. More details can
be found in the commit message to 1639a49ccd ("fs: move S_ISGID
stripping into the vfs_*() helpers")"
* tag 'fs.setgid.v6.0' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
ceph: rely on vfs for setgid stripping
fs: move S_ISGID stripping into the vfs_*() helpers
fs: Add missing umask strip in vfs_tmpfile
fs: add mode_strip_sgid() helper
Move setgid handling out of individual filesystems and into the VFS
itself to stop the proliferation of setgid inheritance bugs.
Creating files that have both the S_IXGRP and S_ISGID bit raised in
directories that themselves have the S_ISGID bit set requires additional
privileges to avoid security issues.
When a filesystem creates a new inode it needs to take care that the
caller is either in the group of the newly created inode or they have
CAP_FSETID in their current user namespace and are privileged over the
parent directory of the new inode. If any of these two conditions is
true then the S_ISGID bit can be raised for an S_IXGRP file and if not
it needs to be stripped.
However, there are several key issues with the current implementation:
* S_ISGID stripping logic is entangled with umask stripping.
If a filesystem doesn't support or enable POSIX ACLs then umask
stripping is done directly in the vfs before calling into the
filesystem.
If the filesystem does support POSIX ACLs then unmask stripping may be
done in the filesystem itself when calling posix_acl_create().
Since umask stripping has an effect on S_ISGID inheritance, e.g., by
stripping the S_IXGRP bit from the file to be created and all relevant
filesystems have to call posix_acl_create() before inode_init_owner()
where we currently take care of S_ISGID handling S_ISGID handling is
order dependent. IOW, whether or not you get a setgid bit depends on
POSIX ACLs and umask and in what order they are called.
Note that technically filesystems are free to impose their own
ordering between posix_acl_create() and inode_init_owner() meaning
that there's additional ordering issues that influence S_SIGID
inheritance.
* Filesystems that don't rely on inode_init_owner() don't get S_ISGID
stripping logic.
While that may be intentional (e.g. network filesystems might just
defer setgid stripping to a server) it is often just a security issue.
This is not just ugly it's unsustainably messy especially since we do
still have bugs in this area years after the initial round of setgid
bugfixes.
So the current state is quite messy and while we won't be able to make
it completely clean as posix_acl_create() is still a filesystem specific
call we can improve the S_SIGD stripping situation quite a bit by
hoisting it out of inode_init_owner() and into the vfs creation
operations. This means we alleviate the burden for filesystems to handle
S_ISGID stripping correctly and can standardize the ordering between
S_ISGID and umask stripping in the vfs.
We add a new helper vfs_prepare_mode() so S_ISGID handling is now done
in the VFS before umask handling. This has S_ISGID handling is
unaffected unaffected by whether umask stripping is done by the VFS
itself (if no POSIX ACLs are supported or enabled) or in the filesystem
in posix_acl_create() (if POSIX ACLs are supported).
The vfs_prepare_mode() helper is called directly in vfs_*() helpers that
create new filesystem objects. We need to move them into there to make
sure that filesystems like overlayfs hat have callchains like:
sys_mknod()
-> do_mknodat(mode)
-> .mknod = ovl_mknod(mode)
-> ovl_create(mode)
-> vfs_mknod(mode)
get S_ISGID stripping done when calling into lower filesystems via
vfs_*() creation helpers. Moving vfs_prepare_mode() into e.g.
vfs_mknod() takes care of that. This is in any case semantically cleaner
because S_ISGID stripping is VFS security requirement.
Security hooks so far have seen the mode with the umask applied but
without S_ISGID handling done. The relevant hooks are called outside of
vfs_*() creation helpers so by calling vfs_prepare_mode() from vfs_*()
helpers the security hooks would now see the mode without umask
stripping applied. For now we fix this by passing the mode with umask
settings applied to not risk any regressions for LSM hooks. IOW, nothing
changes for LSM hooks. It is worth pointing out that security hooks
never saw the mode that is seen by the filesystem when actually creating
the file. They have always been completely misplaced for that to work.
The following filesystems use inode_init_owner() and thus relied on
S_ISGID stripping: spufs, 9p, bfs, btrfs, ext2, ext4, f2fs, hfsplus,
hugetlbfs, jfs, minix, nilfs2, ntfs3, ocfs2, omfs, overlayfs, ramfs,
reiserfs, sysv, ubifs, udf, ufs, xfs, zonefs, bpf, tmpfs.
All of the above filesystems end up calling inode_init_owner() when new
filesystem objects are created through the ->mkdir(), ->mknod(),
->create(), ->tmpfile(), ->rename() inode operations.
Since directories always inherit the S_ISGID bit with the exception of
xfs when irix_sgid_inherit mode is turned on S_ISGID stripping doesn't
apply. The ->symlink() and ->link() inode operations trivially inherit
the mode from the target and the ->rename() inode operation inherits the
mode from the source inode. All other creation inode operations will get
S_ISGID handling via vfs_prepare_mode() when called from their relevant
vfs_*() helpers.
In addition to this there are filesystems which allow the creation of
filesystem objects through ioctl()s or - in the case of spufs -
circumventing the vfs in other ways. If filesystem objects are created
through ioctl()s the vfs doesn't know about it and can't apply regular
permission checking including S_ISGID logic. Therfore, a filesystem
relying on S_ISGID stripping in inode_init_owner() in their ioctl()
callpath will be affected by moving this logic into the vfs. We audited
those filesystems:
* btrfs allows the creation of filesystem objects through various
ioctls(). Snapshot creation literally takes a snapshot and so the mode
is fully preserved and S_ISGID stripping doesn't apply.
Creating a new subvolum relies on inode_init_owner() in
btrfs_new_subvol_inode() but only creates directories and doesn't
raise S_ISGID.
* ocfs2 has a peculiar implementation of reflinks. In contrast to e.g.
xfs and btrfs FICLONE/FICLONERANGE ioctl() that is only concerned with
the actual extents ocfs2 uses a separate ioctl() that also creates the
target file.
Iow, ocfs2 circumvents the vfs entirely here and did indeed rely on
inode_init_owner() to strip the S_ISGID bit. This is the only place
where a filesystem needs to call mode_strip_sgid() directly but this
is self-inflicted pain.
* spufs doesn't go through the vfs at all and doesn't use ioctl()s
either. Instead it has a dedicated system call spufs_create() which
allows the creation of filesystem objects. But spufs only creates
directories and doesn't allo S_SIGID bits, i.e. it specifically only
allows 0777 bits.
* bpf uses vfs_mkobj() but also doesn't allow S_ISGID bits to be created.
The patch will have an effect on ext2 when the EXT2_MOUNT_GRPID mount
option is used, on ext4 when the EXT4_MOUNT_GRPID mount option is used,
and on xfs when the XFS_FEAT_GRPID mount option is used. When any of
these filesystems are mounted with their respective GRPID option then
newly created files inherit the parent directories group
unconditionally. In these cases non of the filesystems call
inode_init_owner() and thus did never strip the S_ISGID bit for newly
created files. Moving this logic into the VFS means that they now get
the S_ISGID bit stripped. This is a user visible change. If this leads
to regressions we will either need to figure out a better way or we need
to revert. However, given the various setgid bugs that we found just in
the last two years this is a regression risk we should take.
Associated with this change is a new set of fstests to enforce the
semantics for all new filesystems.
Link: https://lore.kernel.org/ceph-devel/20220427092201.wvsdjbnc7b4dttaw@wittgenstein [1]
Link: e014f37db1 ("xfs: use setattr_copy to set vfs inode attributes") [2]
Link: 01ea173e10 ("xfs: fix up non-directory creation in SGID directories") [3]
Link: fd84bfdddd ("ceph: fix up non-directory creation in SGID directories") [4]
Link: https://lore.kernel.org/r/1657779088-2242-3-git-send-email-xuyang2018.jy@fujitsu.com
Suggested-by: Dave Chinner <david@fromorbit.com>
Suggested-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-and-Tested-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
[<brauner@kernel.org>: rewrote commit message]
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
All creation paths except for O_TMPFILE handle umask in the vfs directly
if the filesystem doesn't support or enable POSIX ACLs. If the filesystem
does then umask handling is deferred until posix_acl_create().
Because, O_TMPFILE misses umask handling in the vfs it will not honor
umask settings. Fix this by adding the missing umask handling.
Link: https://lore.kernel.org/r/1657779088-2242-2-git-send-email-xuyang2018.jy@fujitsu.com
Fixes: 60545d0d46 ("[O_TMPFILE] it's still short a few helpers, but infrastructure should be OK now...")
Cc: <stable@vger.kernel.org> # 4.19+
Reported-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-and-Tested-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Yang Xu <xuyang2018.jy@fujitsu.com>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Note that validation of ->d_seq after ->d_inode fetch is gone, along
with fetching of ->d_inode itself.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
make handle_mounts() always fetch it. This is just the first step -
the callers of step_into() will stop trying to calculate the sucker,
etc.
The passed value should be equal to dentry->d_inode in all cases;
in RCU mode - fetched after we'd sampled ->d_seq. Might as well
fetch it here. We do need to validate ->d_seq, which duplicates
the check currently done in lookup_fast(); that duplication will
go away shortly.
After that change handle_mounts() always ignores the initial value of
*inode and always sets it on success.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
New field: nd->next_seq. Set to 0 outside of RCU mode, holds the sampled
value for the next dentry to be considered. Used instead of an arseload
of local variables, arguments, etc.
step_into() has lost seq argument; nd->next_seq is used, so dentry passed
to it must be the one ->next_seq is about.
There are two requirements for RCU pathwalk:
1) it should not give a hard failure (other than -ECHILD) unless
non-RCU pathwalk might fail that way given suitable timings.
2) it should not succeed unless non-RCU pathwalk might succeed
with the same end location given suitable timings.
The use of seq numbers is the way we achieve that. Invariant we want
to maintain is:
if RCU pathwalk can reach the state with given nd->path, nd->inode
and nd->seq after having traversed some part of pathname, it must be possible
for non-RCU pathwalk to reach the same nd->path and nd->inode after having
traversed the same part of pathname, and observe the nd->path.dentry->d_seq
equal to what RCU pathwalk has in nd->seq
For transition from parent to child, we sample child's ->d_seq
and verify that parent's ->d_seq remains unchanged. Anything that
disrupts parent-child relationship would've bumped ->d_seq on both.
For transitions from child to parent we sample parent's ->d_seq
and verify that child's ->d_seq has not changed. Same reasoning as
for the previous case applies.
For transition from mountpoint to root of mounted we sample
the ->d_seq of root and verify that nobody has touched mount_lock since
the beginning of pathwalk. That guarantees that mount we'd found had
been there all along, with these mountpoint and root of the mounted.
It would be possible for a non-RCU pathwalk to reach the previous state,
find the same mount and observe its root at the moment we'd sampled
->d_seq of that
For transitions from root of mounted to mountpoint we sample
->d_seq of mountpoint and verify that mount_lock had not been touched
since the beginning of pathwalk. The same reasoning as in the
previous case applies.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
try_to_unlazy()/try_to_unlazy_next() drop LOOKUP_RCU in the
very beginning and do rcu_read_unlock() only at the very end.
However, nothing done in between even looks at the flag in
question; might as well clear it at the same time we unlock.
Note that try_to_unlazy_next() used to call legitimize_mnt(),
which might drop/regain rcu_read_lock() in some cases. This
is no longer true, so we really have rcu_read_lock() held
all along until the end.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The tricky case (__legitimize_mnt() failing after having grabbed
a reference) can be trivially dealt with by leaving nd->path.mnt
non-NULL, for terminate_walk() to drop it.
legitimize_mnt() becomes static after that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Instead of returning NULL when we are in root, just make it return
the current position (and set *seqp and *inodep accordingly).
That collapses the calls of step_into() in handle_dots()
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
read_seqcount_retry() et.al. are inlined and there's enough annotations
for compiler to figure out that those are unlikely to return non-zero.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Validate mount_lock seqcount as soon as we cross into mount in RCU
mode. Sure, ->mnt_root is pinned and will remain so until we
do rcu_read_unlock() anyway, and we will eventually fail to unlazy if
the mount_lock had been touched, but we might run into a hard error
(e.g. -ENOENT) before trying to unlazy. And it's possible to end
up with RCU pathwalk racing with rename() and umount() in a way
that would fail with -ENOENT while non-RCU pathwalk would've
succeeded with any timings.
Once upon a time we hadn't needed that, but analysis had been subtle,
brittle and went out of window as soon as RENAME_EXCHANGE had been
added.
It's narrow, hard to hit and won't get you anything other than
stray -ENOENT that could be arranged in much easier way with the
same priveleges, but it's a bug all the same.
Cc: stable@kernel.org
X-sky-is-falling: unlikely
Fixes: da1ce0670c "vfs: add cross-rename"
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
-----BEGIN PGP SIGNATURE-----
iHUEABYIAB0WIQQqUNBr3gm4hGXdBJlZ7Krx/gZQ6wUCYpvrrgAKCRBZ7Krx/gZQ
6+eZAP9r0c8E1UnUxRI32kQrzndJO2z9mKq6rI9D7GgJe+MtogEAlfynzklqbHzo
fFvczeD0tzLu4aDExtGn6GNGf5gSpw4=
=1blQ
-----END PGP SIGNATURE-----
Merge tag 'pull-18-rc1-work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs pathname updates from Al Viro:
"Several cleanups in fs/namei.c"
* tag 'pull-18-rc1-work.namei' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
namei: cleanup double word in comment
get rid of dead code in legitimize_root()
fs/namei.c:reserve_stack(): tidy up the call of try_to_unlazy()
-----BEGIN PGP SIGNATURE-----
iHUEABYKAB0WIQSQHSd0lITzzeNWNm3h3BK/laaZPAUCYo+nGwAKCRDh3BK/laaZ
PBouAP0VBH/jygclzc42jlRkKjp+wJnF1FifpWOJEtTPiYqhtAD/UWjR/2Sy4TMT
fRsw9N9/FXxcXShjg3U42fpCNSVEqgM=
=oY4z
-----END PGP SIGNATURE-----
Merge tag 'ovl-update-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs
Pull overlayfs updates from Miklos Szeredi:
- Support idmapped layers in overlayfs (Christian Brauner)
- Add a fix to exportfs that is relevant to open_by_handle_at(2) as
well
- Introduce new lookup helpers that allow passing mnt_userns into
inode_permission()
* tag 'ovl-update-5.19' of git://git.kernel.org/pub/scm/linux/kernel/git/mszeredi/vfs:
ovl: support idmapped layers
ovl: handle idmappings in ovl_xattr_{g,s}et()
ovl: handle idmappings in layer open helpers
ovl: handle idmappings in ovl_permission()
ovl: use ovl_copy_{real,upper}attr() wrappers
ovl: store lower path in ovl_inode
ovl: handle idmappings for layer lookup
ovl: handle idmappings for layer fileattrs
ovl: use ovl_path_getxattr() wrapper
ovl: use ovl_lookup_upper() wrapper
ovl: use ovl_do_notify_change() wrapper
ovl: pass layer mnt to ovl_open_realfile()
ovl: pass ofs to setattr operations
ovl: handle idmappings in creation operations
ovl: add ovl_upper_mnt_userns() wrapper
ovl: pass ofs to creation operations
ovl: use wrappers to all vfs_*xattr() calls
exportfs: support idmapped mounts
fs: add two trivial lookup helpers
subsystems. Most notably some maintenance work in ocfs2 and initramfs.
-----BEGIN PGP SIGNATURE-----
iHUEABYKAB0WIQTTMBEPP41GrTpTJgfdBJ7gKXxAjgUCYo/6xQAKCRDdBJ7gKXxA
jkD9AQCPczLBbRWpe1edL+5VHvel9ePoHQmvbHQnufdTh9rB5QEAu0Uilxz4q9cx
xSZypNhj2n9f8FCYca/ZrZneBsTnAA8=
=AJEO
-----END PGP SIGNATURE-----
Merge tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc updates from Andrew Morton:
"The non-MM patch queue for this merge window.
Not a lot of material this cycle. Many singleton patches against
various subsystems. Most notably some maintenance work in ocfs2
and initramfs"
* tag 'mm-nonmm-stable-2022-05-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (65 commits)
kcov: update pos before writing pc in trace function
ocfs2: dlmfs: fix error handling of user_dlm_destroy_lock
ocfs2: dlmfs: don't clear USER_LOCK_ATTACHED when destroying lock
fs/ntfs: remove redundant variable idx
fat: remove time truncations in vfat_create/vfat_mkdir
fat: report creation time in statx
fat: ignore ctime updates, and keep ctime identical to mtime in memory
fat: split fat_truncate_time() into separate functions
MAINTAINERS: add Muchun as a memcg reviewer
proc/sysctl: make protected_* world readable
ia64: mca: drop redundant spinlock initialization
tty: fix deadlock caused by calling printk() under tty_port->lock
relay: remove redundant assignment to pointer buf
fs/ntfs3: validate BOOT sectors_per_clusters
lib/string_helpers: fix not adding strarray to device's resource list
kernel/crash_core.c: remove redundant check of ck_cmdline
ELF, uapi: fixup ELF_ST_TYPE definition
ipc/mqueue: use get_tree_nodev() in mqueue_get_tree()
ipc: update semtimedop() to use hrtimer
ipc/sem: remove redundant assignments
...
Combination of LOOKUP_IS_SCOPED and NULL nd->root.mnt is impossible
after successful path_init(). All places where ->root.mnt might
become NULL do that only if LOOKUP_IS_SCOPED is not there and
path_init() itself can return success without setting nd->root
only if ND_ROOT_PRESET had been set (in which case nd->root
had been set by caller and never changed) or if the name had
been a relative one *and* none of the bits in LOOKUP_IS_SCOPED
had been present.
Since all calls of legitimize_root() must be downstream of successful
path_init(), the check for !nd->root.mnt && (nd->flags & LOOKUP_IS_SCOPED)
is pure paranoia.
FWIW, it had been discussed (and agreed upon) with Aleksa back when
scoped lookups had been merged; looks like that had fallen through the
cracks back then.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
!foo() != 0 is a strange way to spell !foo(); fallout from
"fs: make unlazy_walk() error handling consistent"...
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
protected_* files have 600 permissions which prevents non-superuser from
reading them.
Container like "AWS greengrass" refuse to launch unless
protected_hardlinks and protected_symlinks are set. When containers like
these run with "userns-remap" or "--user" mapping container's root to
non-superuser on host, they fail to run due to denied read access to these
files.
As these protections are hardly a secret, and do not possess any security
risk, making them world readable.
Though above greengrass usecase needs read access to only
protected_hardlinks and protected_symlinks files, setting all other
protected_* files to 644 to keep consistency.
Link: http://lkml.kernel.org/r/20200709235115.56954-1-jpitti@cisco.com
Fixes: 800179c9b8 ("fs: add link restrictions")
Signed-off-by: Julius Hemanth Pitti <jpitti@cisco.com>
Acked-by: Kees Cook <keescook@chromium.org>
Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
pagecache_write_begin() and pagecache_write_end() are now trivial
wrappers, so call the aops directly.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Stop using AOP_FLAG_NOFS in favour of the scoped memory API.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
There are no callers of __page_symlink() left, so we can remove that
entry point.
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Similar to the addition of lookup_one() add a version of
lookup_one_unlocked() and lookup_one_positive_unlocked() that take
idmapped mounts into account. This is required to port overlay to
support idmapped base layers.
Cc: <linux-fsdevel@vger.kernel.org>
Tested-by: Giuseppe Scrivano <gscrivan@redhat.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
When asked to create a path ending '/', but which is not to be a
directory (LOOKUP_DIRECTORY not set), filename_create() will never try
to create the file. If it doesn't exist, -ENOENT is reported.
However, it still passes LOOKUP_CREATE|LOOKUP_EXCL to the filesystems
->lookup() function, even though there is no intent to create. This is
misleading and can cause incorrect behaviour.
If you try
ln -s foo /path/dir/
where 'dir' is a directory on an NFS filesystem which is not currently
known in the dcache, this will fail with ENOENT.
But as the name is not in the dcache, nfs_lookup gets called with
LOOKUP_CREATE|LOOKUP_EXCL and so it returns NULL without performing any
lookup, with the expectation that a subsequent call to create the target
will be made, and the lookup can be combined with the creation. In the
case with a trailing '/' and no LOOKUP_DIRECTORY, that call is never
made. Instead filename_create() sees that the dentry is not (yet)
positive and returns -ENOENT - even though the directory actually
exists.
So only set LOOKUP_CREATE|LOOKUP_EXCL if there really is an intent to
create, and use the absence of these flags to decide if -ENOENT should
be returned.
Note that filename_parentat() is only interested in LOOKUP_REVAL, so we
split that out and store it in 'reval_flag'. __lookup_hash() then gets
reval_flag combined with whatever create flags were determined to be
needed.
Reviewed-by: David Disseldorp <ddiss@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neilb@suse.de>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-----BEGIN PGP SIGNATURE-----
iQEzBAABCAAdFiEEq1nRK9aeMoq1VSgcnJ2qBz9kQNkFAmHz0QsACgkQnJ2qBz9k
QNkN+AgA6XqWHKYyElfgJFt1UqaoNMz/Faz9H/+PKiBNSTf6/+67D+V7DFz6jJrv
dDwHNzfDg9kR+pbAAPwhl2jfnQoUlsr019Hrqa5HpWlj5geVpbdunYUzS2WOkwqD
/m+brcLgPdKb2uIysj6wOh9B7wa8V9ksl3EjQvvwaHaU0p1YLUqidVXucYvs8DUo
bgXNaj9GmeysxnmU+aILotWuuXH2vOP4Q2Uk4qz3rN6xW9eEXtpQ4y7gWBp/GA8y
Ia8FtFdQdvlSDOJYMdPOTBu5RB7gY9ElrapvVaWNYtCWI/jRv666nZsLaERYNhLN
uUsG4MWjYbOqW5XqFDbSOwbDqvMh5Q==
=mEFA
-----END PGP SIGNATURE-----
Merge tag 'fsnotify_for_v5.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
Pull fsnotify fixes from Jan Kara:
"Fixes for userspace breakage caused by fsnotify changes ~3 years ago
and one fanotify cleanup"
* tag 'fsnotify_for_v5.17-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs:
fsnotify: fix fsnotify hooks in pseudo filesystems
fsnotify: invalidate dcache before IN_DELETE event
fanotify: remove variable set but not used
Apparently, there are some applications that use IN_DELETE event as an
invalidation mechanism and expect that if they try to open a file with
the name reported with the delete event, that it should not contain the
content of the deleted file.
Commit 49246466a9 ("fsnotify: move fsnotify_nameremove() hook out of
d_delete()") moved the fsnotify delete hook before d_delete() so fsnotify
will have access to a positive dentry.
This allowed a race where opening the deleted file via cached dentry
is now possible after receiving the IN_DELETE event.
To fix the regression, create a new hook fsnotify_delete() that takes
the unlinked inode as an argument and use a helper d_delete_notify() to
pin the inode, so we can pass it to fsnotify_delete() after d_delete().
Backporting hint: this regression is from v5.3. Although patch will
apply with only trivial conflicts to v5.4 and v5.10, it won't build,
because fsnotify_delete() implementation is different in each of those
versions (see fsnotify_link()).
A follow up patch will fix the fsnotify_unlink/rmdir() calls in pseudo
filesystem that do not need to call d_delete().
Link: https://lore.kernel.org/r/20220120215305.282577-1-amir73il@gmail.com
Reported-by: Ivan Delalande <colona@arista.com>
Link: https://lore.kernel.org/linux-fsdevel/YeNyzoDM5hP5LtGW@visor/
Fixes: 49246466a9 ("fsnotify: move fsnotify_nameremove() hook out of d_delete()")
Cc: stable@vger.kernel.org # v5.3+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Jan Kara <jack@suse.cz>
kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.
To help with this maintenance let's start by moving sysctls to places
where they actually belong. The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.
So move namei's own sysctl knobs to its own file.
Other than the move we also avoid initializing two static variables to 0
as this is not needed:
* sysctl_protected_symlinks
* sysctl_protected_hardlinks
Link: https://lkml.kernel.org/r/20211129205548.605569-8-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Antti Palosaari <crope@iki.fi>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Lukas Middendorf <kernel@tuxforce.de>
Cc: Stephen Kitt <steve@sk2.org>
Cc: Xiaoming Ni <nixiaoming@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-----BEGIN PGP SIGNATURE-----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=bcaq
-----END PGP SIGNATURE-----
Merge tag 'locks-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux
Pull file locking updates from Jeff Layton:
"Most of this is just follow-on cleanup work of documentation and
comments from the mandatory locking removal in v5.15.
The only real functional change is that LOCK_MAND flock() support is
also being removed, as it has basically been non-functional since the
v2.5 days"
* tag 'locks-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux:
fs: remove leftover comments from mandatory locking removal
locks: remove changelog comments
docs: fs: locks.rst: update comment about mandatory file locking
Documentation: remove reference to now removed mandatory-locking doc
locks: remove LOCK_MAND flock lock support
Mixing NULL and ERR_PTR() just in case is a Bad Idea(tm). For
struct filename the former is wrong - failures are reported
as ERR_PTR(...), not as NULL.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
