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The issue was caused by dput(upper) being called before
ovl_dentry_update_reval(), while upper->d_flags was still
accessed in ovl_dentry_remote().
Move dput(upper) after its last use to prevent use-after-free.
BUG: KASAN: slab-use-after-free in ovl_dentry_remote fs/overlayfs/util.c:162 [inline]
BUG: KASAN: slab-use-after-free in ovl_dentry_update_reval+0xd2/0xf0 fs/overlayfs/util.c:167
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0xc3/0x620 mm/kasan/report.c:488
kasan_report+0xd9/0x110 mm/kasan/report.c:601
ovl_dentry_remote fs/overlayfs/util.c:162 [inline]
ovl_dentry_update_reval+0xd2/0xf0 fs/overlayfs/util.c:167
ovl_link_up fs/overlayfs/copy_up.c:610 [inline]
ovl_copy_up_one+0x2105/0x3490 fs/overlayfs/copy_up.c:1170
ovl_copy_up_flags+0x18d/0x200 fs/overlayfs/copy_up.c:1223
ovl_rename+0x39e/0x18c0 fs/overlayfs/dir.c:1136
vfs_rename+0xf84/0x20a0 fs/namei.c:4893
...
</TASK>
Fixes: b07d5cc93e1b ("ovl: update of dentry revalidate flags after copy up")
Reported-by: syzbot+316db8a1191938280eb6@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=316db8a1191938280eb6
Signed-off-by: Vasiliy Kovalev <kovalev@altlinux.org>
Link: https://lore.kernel.org/r/20250214215148.761147-1-kovalev@altlinux.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Pull misc vfs cleanups from Al Viro:
"Two unrelated patches - one is a removal of long-obsolete include in
overlayfs (it used to need fs/internal.h, but the extern it wanted has
been moved back to include/linux/namei.h) and another introduces
convenience helper constructing struct qstr by a NUL-terminated
string"
* tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
add a string-to-qstr constructor
fs/overlayfs/namei.c: get rid of include ../internal.h
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull vfs d_revalidate updates from Al Viro:
"Provide stable parent and name to ->d_revalidate() instances
Most of the filesystem methods where we care about dentry name and
parent have their stability guaranteed by the callers;
->d_revalidate() is the major exception.
It's easy enough for callers to supply stable values for expected name
and expected parent of the dentry being validated. That kills quite a
bit of boilerplate in ->d_revalidate() instances, along with a bunch
of races where they used to access ->d_name without sufficient
precautions"
* tag 'pull-revalidate' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
9p: fix ->rename_sem exclusion
orangefs_d_revalidate(): use stable parent inode and name passed by caller
ocfs2_dentry_revalidate(): use stable parent inode and name passed by caller
nfs: fix ->d_revalidate() UAF on ->d_name accesses
nfs{,4}_lookup_validate(): use stable parent inode passed by caller
gfs2_drevalidate(): use stable parent inode and name passed by caller
fuse_dentry_revalidate(): use stable parent inode and name passed by caller
vfat_revalidate{,_ci}(): use stable parent inode passed by caller
exfat_d_revalidate(): use stable parent inode passed by caller
fscrypt_d_revalidate(): use stable parent inode passed by caller
ceph_d_revalidate(): propagate stable name down into request encoding
ceph_d_revalidate(): use stable parent inode passed by caller
afs_d_revalidate(): use stable name and parent inode passed by caller
Pass parent directory inode and expected name to ->d_revalidate()
generic_ci_d_compare(): use shortname_storage
ext4 fast_commit: make use of name_snapshot primitives
dissolve external_name.u into separate members
make take_dentry_name_snapshot() lockless
dcache: back inline names with a struct-wrapped array of unsigned long
make sure that DNAME_INLINE_LEN is a multiple of word size
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->d_revalidate() often needs to access dentry parent and name; that has
to be done carefully, since the locking environment varies from caller
to caller. We are not guaranteed that dentry in question will not be
moved right under us - not unless the filesystem is such that nothing
on it ever gets renamed.
It can be dealt with, but that results in boilerplate code that isn't
even needed - the callers normally have just found the dentry via dcache
lookup and want to verify that it's in the right place; they already
have the values of ->d_parent and ->d_name stable. There is a couple
of exceptions (overlayfs and, to less extent, ecryptfs), but for the
majority of calls that song and dance is not needed at all.
It's easier to make ecryptfs and overlayfs find and pass those values if
there's a ->d_revalidate() instance to be called, rather than doing that
in the instances.
This commit only changes the calling conventions; making use of supplied
values is left to followups.
NOTE: some instances need more than just the parent - things like CIFS
may need to build an entire path from filesystem root, so they need
more precautions than the usual boilerplate. This series doesn't
do anything to that need - these filesystems have to keep their locking
mechanisms (rename_lock loops, use of dentry_path_raw(), private rwsem
a-la v9fs).
One thing to keep in mind when using name is that name->name will normally
point into the pathname being resolved; the filename in question occupies
name->len bytes starting at name->name, and there is NUL somewhere after it,
but it the next byte might very well be '/' rather than '\0'. Do not
ignore name->len.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Gabriel Krisman Bertazi <gabriel@krisman.be>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull cred refcount updates from Christian Brauner:
"For the v6.13 cycle we switched overlayfs to a variant of
override_creds() that doesn't take an extra reference. To this end the
{override,revert}_creds_light() helpers were introduced.
This generalizes the idea behind {override,revert}_creds_light() to
the {override,revert}_creds() helpers. Afterwards overriding and
reverting credentials is reference count free unless the caller
explicitly takes a reference.
All callers have been appropriately ported"
* tag 'kernel-6.14-rc1.cred' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (30 commits)
cred: fold get_new_cred_many() into get_cred_many()
cred: remove unused get_new_cred()
nfsd: avoid pointless cred reference count bump
cachefiles: avoid pointless cred reference count bump
dns_resolver: avoid pointless cred reference count bump
trace: avoid pointless cred reference count bump
cgroup: avoid pointless cred reference count bump
acct: avoid pointless reference count bump
io_uring: avoid pointless cred reference count bump
smb: avoid pointless cred reference count bump
cifs: avoid pointless cred reference count bump
cifs: avoid pointless cred reference count bump
ovl: avoid pointless cred reference count bump
open: avoid pointless cred reference count bump
nfsfh: avoid pointless cred reference count bump
nfs/nfs4recover: avoid pointless cred reference count bump
nfs/nfs4idmap: avoid pointless reference count bump
nfs/localio: avoid pointless cred reference count bumps
coredump: avoid pointless cred reference count bump
binfmt_misc: avoid pointless cred reference count bump
...
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Added for the sake of vfs_path_lookup(), which is in linux/namei.h
these days.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Dmitry Safonov reported that a WARN_ON() assertion can be trigered by
userspace when calling inotify_show_fdinfo() for an overlayfs watched
inode, whose dentry aliases were discarded with drop_caches.
The WARN_ON() assertion in inotify_show_fdinfo() was removed, because
it is possible for encoding file handle to fail for other reason, but
the impact of failing to encode an overlayfs file handle goes beyond
this assertion.
As shown in the LTP test case mentioned in the link below, failure to
encode an overlayfs file handle from a non-aliased inode also leads to
failure to report an fid with FAN_DELETE_SELF fanotify events.
As Dmitry notes in his analyzis of the problem, ovl_encode_fh() fails
if it cannot find an alias for the inode, but this failure can be fixed.
ovl_encode_fh() seldom uses the alias and in the case of non-decodable
file handles, as is often the case with fanotify fid info,
ovl_encode_fh() never needs to use the alias to encode a file handle.
Defer finding an alias until it is actually needed so ovl_encode_fh()
will not fail in the common case of FAN_DELETE_SELF fanotify events.
Fixes: 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles")
Reported-by: Dmitry Safonov <dima@arista.com>
Closes: https://lore.kernel.org/linux-fsdevel/CAOQ4uxiie81voLZZi2zXS1BziXZCM24nXqPAxbu8kxXCUWdwOg@mail.gmail.com/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20250105162404.357058-3-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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We want to be able to encode an fid from an inode with no alias.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20250105162404.357058-2-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Encoding file handles is usually performed by a filesystem >encode_fh()
method that may fail for various reasons.
The legacy users of exportfs_encode_fh(), namely, nfsd and
name_to_handle_at(2) syscall are ready to cope with the possibility
of failure to encode a file handle.
There are a few other users of exportfs_encode_{fh,fid}() that
currently have a WARN_ON() assertion when ->encode_fh() fails.
Relax those assertions because they are wrong.
The second linked bug report states commit 16aac5ad1fa9 ("ovl: support
encoding non-decodable file handles") in v6.6 as the regressing commit,
but this is not accurate.
The aforementioned commit only increases the chances of the assertion
and allows triggering the assertion with the reproducer using overlayfs,
inotify and drop_caches.
Triggering this assertion was always possible with other filesystems and
other reasons of ->encode_fh() failures and more particularly, it was
also possible with the exact same reproducer using overlayfs that is
mounted with options index=on,nfs_export=on also on kernels < v6.6.
Therefore, I am not listing the aforementioned commit as a Fixes commit.
Backport hint: this patch will have a trivial conflict applying to
v6.6.y, and other trivial conflicts applying to stable kernels < v6.6.
Reported-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com
Tested-by: syzbot+ec07f6f5ce62b858579f@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/linux-unionfs/671fd40c.050a0220.4735a.024f.GAE@google.com/
Reported-by: Dmitry Safonov <dima@arista.com>
Closes: https://lore.kernel.org/linux-fsdevel/CAGrbwDTLt6drB9eaUagnQVgdPBmhLfqqxAf3F+Juqy_o6oP8uw@mail.gmail.com/
Cc: stable@vger.kernel.org
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20241219115301.465396-1-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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security_inode_copy_up() allocates a set of new credentials and has
taken a reference count.
Link: https://lore.kernel.org/r/20241125-work-cred-v2-18-68b9d38bb5b2@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Rename all calls to revert_creds_light() back to revert_creds().
Link: https://lore.kernel.org/r/20241125-work-cred-v2-6-68b9d38bb5b2@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Rename all calls to override_creds_light() back to overrid_creds().
Link: https://lore.kernel.org/r/20241125-work-cred-v2-5-68b9d38bb5b2@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Convert all calls to revert_creds() over to explicitly dropping
reference counts in preparation for converting revert_creds() to
revert_creds_light() semantics.
Link: https://lore.kernel.org/r/20241125-work-cred-v2-3-68b9d38bb5b2@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Convert all callers from override_creds() to
override_creds_light(get_new_cred()) in preparation of making
override_creds() not take a separate reference at all.
Link: https://lore.kernel.org/r/20241125-work-cred-v2-1-68b9d38bb5b2@kernel.org
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs
Pull overlayfs updates from Amir Goldstein:
- Fix a syzbot reported NULL pointer deref with bfs lower layers
- Fix a copy up failure of large file from lower fuse fs
- Followup cleanup of backing_file API from Miklos
- Introduction and use of revert/override_creds_light() helpers, that
were suggested by Christian as a mitigation to cache line bouncing
and false sharing of fields in overlayfs creator_cred long lived
struct cred copy.
- Store up to two backing file references (upper and lower) in an
ovl_file container instead of storing a single backing file in
file->private_data.
This is used to avoid the practice of opening a short lived backing
file for the duration of some file operations and to avoid the
specialized use of FDPUT_FPUT in such occasions, that was getting in
the way of Al's fd_file() conversions.
* tag 'ovl-update-6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
ovl: Filter invalid inodes with missing lookup function
ovl: convert ovl_real_fdget() callers to ovl_real_file()
ovl: convert ovl_real_fdget_path() callers to ovl_real_file_path()
ovl: store upper real file in ovl_file struct
ovl: allocate a container struct ovl_file for ovl private context
ovl: do not open non-data lower file for fsync
ovl: Optimize override/revert creds
ovl: pass an explicit reference of creators creds to callers
ovl: use wrapper ovl_revert_creds()
fs/backing-file: Convert to revert/override_creds_light()
cred: Add a light version of override/revert_creds()
backing-file: clean up the API
ovl: properly handle large files in ovl_security_fileattr
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Add a check to the ovl_dentry_weird() function to prevent the
processing of directory inodes that lack the lookup function.
This is important because such inodes can cause errors in overlayfs
when passed to the lowerstack.
Reported-by: syzbot+a8c9d476508bd14a90e5@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?extid=a8c9d476508bd14a90e5
Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Link: https://lore.kernel.org/linux-unionfs/CAJfpegvx-oS9XGuwpJx=Xe28_jzWx5eRo1y900_ZzWY+=gGzUg@mail.gmail.com/
Signed-off-by: Vasiliy Kovalev <kovalev@altlinux.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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Pull statx updates from Al Viro:
"Sanitize struct filename and lookup flags handling in statx and
friends"
* tag 'pull-statx' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
libfs: kill empty_dir_getattr()
fs: Simplify getattr interface function checking AT_GETATTR_NOSEC flag
fs/stat.c: switch to CLASS(fd_raw)
kill getname_statx_lookup_flags()
io_statx_prep(): use getname_uflags()
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull overlayfs updates from Christian Brauner:
"Make overlayfs support specifying layers through file descriptors.
Currently overlayfs only allows specifying layers through path names.
This is inconvenient for users that want to assemble an overlayfs
mount purely based on file descriptors:
This enables user to specify both:
fsconfig(fd_overlay, FSCONFIG_SET_FD, "upperdir+", NULL, fd_upper);
fsconfig(fd_overlay, FSCONFIG_SET_FD, "workdir+", NULL, fd_work);
fsconfig(fd_overlay, FSCONFIG_SET_FD, "lowerdir+", NULL, fd_lower1);
fsconfig(fd_overlay, FSCONFIG_SET_FD, "lowerdir+", NULL, fd_lower2);
in addition to:
fsconfig(fd_overlay, FSCONFIG_SET_STRING, "upperdir+", "/upper", 0);
fsconfig(fd_overlay, FSCONFIG_SET_STRING, "workdir+", "/work", 0);
fsconfig(fd_overlay, FSCONFIG_SET_STRING, "lowerdir+", "/lower1", 0);
fsconfig(fd_overlay, FSCONFIG_SET_STRING, "lowerdir+", "/lower2", 0);
There's also a large set of new overlayfs selftests to test new
features and some older properties"
* tag 'vfs-6.13.ovl' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests: add test for specifying 500 lower layers
selftests: add overlayfs fd mounting selftests
selftests: use shared header
Documentation,ovl: document new file descriptor based layers
ovl: specify layers via file descriptors
fs: add helper to use mount option as path or fd
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git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs file updates from Christian Brauner:
"This contains changes the changes for files for this cycle:
- Introduce a new reference counting mechanism for files.
As atomic_inc_not_zero() is implemented with a try_cmpxchg() loop
it has O(N^2) behaviour under contention with N concurrent
operations and it is in a hot path in __fget_files_rcu().
The rcuref infrastructures remedies this problem by using an
unconditional increment relying on safe- and dead zones to make
this work and requiring rcu protection for the data structure in
question. This not just scales better it also introduces overflow
protection.
However, in contrast to generic rcuref, files require a memory
barrier and thus cannot rely on *_relaxed() atomic operations and
also require to be built on atomic_long_t as having massive amounts
of reference isn't unheard of even if it is just an attack.
This adds a file specific variant instead of making this a generic
library.
This has been tested by various people and it gives consistent
improvement up to 3-5% on workloads with loads of threads.
- Add a fastpath for find_next_zero_bit(). Skip 2-levels searching
via find_next_zero_bit() when there is a free slot in the word that
contains the next fd. This improves pts/blogbench-1.1.0 read by 8%
and write by 4% on Intel ICX 160.
- Conditionally clear full_fds_bits since it's very likely that a bit
in full_fds_bits has been cleared during __clear_open_fds(). This
improves pts/blogbench-1.1.0 read up to 13%, and write up to 5% on
Intel ICX 160.
- Get rid of all lookup_*_fdget_rcu() variants. They were used to
lookup files without taking a reference count. That became invalid
once files were switched to SLAB_TYPESAFE_BY_RCU and now we're
always taking a reference count. Switch to an already existing
helper and remove the legacy variants.
- Remove pointless includes of <linux/fdtable.h>.
- Avoid cmpxchg() in close_files() as nobody else has a reference to
the files_struct at that point.
- Move close_range() into fs/file.c and fold __close_range() into it.
- Cleanup calling conventions of alloc_fdtable() and expand_files().
- Merge __{set,clear}_close_on_exec() into one.
- Make __set_open_fd() set cloexec as well instead of doing it in two
separate steps"
* tag 'vfs-6.13.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
selftests: add file SLAB_TYPESAFE_BY_RCU recycling stressor
fs: port files to file_ref
fs: add file_ref
expand_files(): simplify calling conventions
make __set_open_fd() set cloexec state as well
fs: protect backing files with rcu
file.c: merge __{set,clear}_close_on_exec()
alloc_fdtable(): change calling conventions.
fs/file.c: add fast path in find_next_fd()
fs/file.c: conditionally clear full_fds
fs/file.c: remove sanity_check and add likely/unlikely in alloc_fd()
move close_range(2) into fs/file.c, fold __close_range() into it
close_files(): don't bother with xchg()
remove pointless includes of <linux/fdtable.h>
get rid of ...lookup...fdget_rcu() family
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Stop using struct fd to return a real file from ovl_real_fdget(),
because we no longer return a temporary file object and the callers
always get a borrowed file reference.
Rename the helper to ovl_real_file(), return a borrowed reference of
the real file that is referenced from the overlayfs file or an error.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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Stop using struct fd to return a real file from ovl_real_fdget_path(),
because we no longer return a temporary file object and the callers
always get a borrowed file reference.
Rename the helper to ovl_real_file_path(), return a borrowed reference
of the real file that is referenced from the overlayfs file or an error.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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When an overlayfs file is opened as lower and then the file is copied up,
every operation on the overlayfs open file will open a temporary backing
file to the upper dentry and close it at the end of the operation.
Store the upper real file along side the original (lower) real file in
ovl_file instead of opening a temporary upper file on every operation.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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Instead of using ->private_data to point at realfile directly, so
that we can add more context per ovl open file.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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ovl_fsync() with !datasync opens a backing file from the top most dentry
in the stack, checks if this dentry is non-upper and skips the fsync.
In case of an overlay dentry stack with lower data and lower metadata
above it, but without an upper metadata above it, the backing file is
opened from the top most lower metadata dentry and never used.
Refactor the helper ovl_real_fdget_meta() into ovl_real_fdget_path() and
open code the checks for non-upper inode in ovl_fsync(), so in that case
we can avoid the unneeded backing file open.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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Use override_creds_light() in ovl_override_creds() and
revert_creds_light() in ovl_revert_creds().
The _light() functions do not change the 'usage' of the credentials in
question, as they refer to the credentials associated with the
mounter, which have a longer lifetime.
In ovl_setup_cred_for_create(), do not need to modify the mounter
credentials (returned by override_creds_light()) 'usage' counter.
Add a warning to verify that we are indeed working with the mounter
credentials (stored in the superblock). Failure in this assumption
means that creds may leak.
Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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ovl_setup_cred_for_create() decrements one refcount of new creds and
ovl_revert_creds() in callers decrements the last refcount.
In preparation to revert_creds_light() back to caller creds, pass an
explicit reference of the creators creds to the callers and drop the
refcount explicitly in the callers after ovl_revert_creds().
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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Commit 8a924db2d7b5 ("fs: Pass AT_GETATTR_NOSEC flag to getattr interface
function")' introduced the AT_GETATTR_NOSEC flag to ensure that the
call paths only call vfs_getattr_nosec if it is set instead of vfs_getattr.
Now, simplify the getattr interface functions of filesystems where the flag
AT_GETATTR_NOSEC is checked.
There is only a single caller of inode_operations getattr function and it
is located in fs/stat.c in vfs_getattr_nosec. The caller there is the only
one from which the AT_GETATTR_NOSEC flag is passed from.
Two filesystems are checking this flag in .getattr and the flag is always
passed to them unconditionally from only vfs_getattr_nosec:
- ecryptfs: Simplify by always calling vfs_getattr_nosec in
ecryptfs_getattr. From there the flag is passed to no other
function and this function is not called otherwise.
- overlayfs: Simplify by always calling vfs_getattr_nosec in
ovl_getattr. From there the flag is passed to no other
function and this function is not called otherwise.
The query_flags in vfs_getattr_nosec will mask-out AT_GETATTR_NOSEC from
any caller using AT_STATX_SYNC_TYPE as mask so that the flag is not
important inside this function. Also, since no filesystem is checking the
flag anymore, remove the flag entirely now, including the BUG_ON check that
never triggered.
The net change of the changes here combined with the original commit is
that ecryptfs and overlayfs do not call vfs_getattr but only
vfs_getattr_nosec.
Fixes: 8a924db2d7b5 ("fs: Pass AT_GETATTR_NOSEC flag to getattr interface function")
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Closes: https://lore.kernel.org/linux-fsdevel/20241101011724.GN1350452@ZenIV/T/#u
Cc: Tyler Hicks <code@tyhicks.com>
Cc: ecryptfs@vger.kernel.org
Cc: Miklos Szeredi <miklos@szeredi.hu>
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: linux-unionfs@vger.kernel.org
Cc: Christian Brauner <brauner@kernel.org>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Introduce ovl_revert_creds() wrapper of revert_creds() to
match callers of ovl_override_creds().
Suggested-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Vinicius Costa Gomes <vinicius.gomes@intel.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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- Pass iocb to ctx->end_write() instead of file + pos
- Get rid of ctx->user_file, which is redundant most of the time
- Instead pass iocb to backing_file_splice_read and
backing_file_splice_write
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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dentry_open in ovl_security_fileattr fails for any file
larger than 2GB if open method of the underlying filesystem
calls generic_file_open (e.g. fusefs).
The issue can be reproduce using the following script:
(passthrough_ll is an example app from libfuse).
$ D=/opt/test/mnt
$ mkdir -p ${D}/{source,base,top/uppr,top/work,ovlfs}
$ dd if=/dev/zero of=${D}/source/zero.bin bs=1G count=2
$ passthrough_ll -o source=${D}/source ${D}/base
$ mount -t overlay overlay \
-olowerdir=${D}/base,upperdir=${D}/top/uppr,workdir=${D}/top/work \
${D}/ovlfs
$ chmod 0777 ${D}/mnt/ovlfs/zero.bin
Running this script results in "Value too large for defined data type"
error message from chmod.
Signed-off-by: Oleksandr Tymoshenko <ovt@google.com>
Fixes: 72db82115d2b ("ovl: copy up sync/noatime fileattr flags")
Cc: stable@vger.kernel.org # v5.15+
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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This is needed for extending fuse inode size after fuse passthrough write.
Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Link: https://lore.kernel.org/linux-fsdevel/CAJfpegs=cvZ_NYy6Q_D42XhYS=Sjj5poM1b5TzXzOVvX=R36aA@mail.gmail.com/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Currently overlayfs only allows specifying layers through path names.
This is inconvenient for users such as systemd that want to assemble an
overlayfs mount purely based on file descriptors.
This enables user to specify both:
fsconfig(fd_overlay, FSCONFIG_SET_FD, "upperdir+", NULL, fd_upper);
fsconfig(fd_overlay, FSCONFIG_SET_FD, "workdir+", NULL, fd_work);
fsconfig(fd_overlay, FSCONFIG_SET_FD, "lowerdir+", NULL, fd_lower1);
fsconfig(fd_overlay, FSCONFIG_SET_FD, "lowerdir+", NULL, fd_lower2);
in addition to:
fsconfig(fd_overlay, FSCONFIG_SET_STRING, "upperdir+", "/upper", 0);
fsconfig(fd_overlay, FSCONFIG_SET_STRING, "workdir+", "/work", 0);
fsconfig(fd_overlay, FSCONFIG_SET_STRING, "lowerdir+", "/lower1", 0);
fsconfig(fd_overlay, FSCONFIG_SET_STRING, "lowerdir+", "/lower2", 0);
Link: https://lore.kernel.org/r/20241014-work-overlayfs-v3-2-32b3fed1286e@kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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some of those used to be needed, some had been cargo-culted for
no reason...
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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ovl_open_realfile() is wrongly called twice after conversion to
new struct fd.
Fixes: 88a2f6468d01 ("struct fd: representation change")
Reported-by: syzbot+d9efec94dcbfa0de1c07@syzkaller.appspotmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull 'struct fd' updates from Al Viro:
"Just the 'struct fd' layout change, with conversion to accessor
helpers"
* tag 'pull-stable-struct_fd' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
add struct fd constructors, get rid of __to_fd()
struct fd: representation change
introduce fd_file(), convert all accessors to it.
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git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs
Pull overlayfs updates from Amir Goldstein:
- Increase robustness of overlayfs to crashes in the case of underlying
filesystems that to not guarantee metadata ordering to persistent
storage (problem was reported with ubifs).
- Deny mount inside container with features that require root
privileges to work properly, instead of failing operations later.
- Some clarifications to overlayfs documentation.
* tag 'ovl-update-6.12' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
ovl: fail if trusted xattrs are needed but caller lacks permission
overlayfs.rst: update metacopy section in overlayfs documentation
ovl: fsync after metadata copy-up
ovl: don't set the superblock's errseq_t manually
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git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm
Pull lsm updates from Paul Moore:
- Move the LSM framework to static calls
This transitions the vast majority of the LSM callbacks into static
calls. Those callbacks which haven't been converted were left as-is
due to the general ugliness of the changes required to support the
static call conversion; we can revisit those callbacks at a future
date.
- Add the Integrity Policy Enforcement (IPE) LSM
This adds a new LSM, Integrity Policy Enforcement (IPE). There is
plenty of documentation about IPE in this patches, so I'll refrain
from going into too much detail here, but the basic motivation behind
IPE is to provide a mechanism such that administrators can restrict
execution to only those binaries which come from integrity protected
storage, e.g. a dm-verity protected filesystem. You will notice that
IPE requires additional LSM hooks in the initramfs, dm-verity, and
fs-verity code, with the associated patches carrying ACK/review tags
from the associated maintainers. We couldn't find an obvious
maintainer for the initramfs code, but the IPE patchset has been
widely posted over several years.
Both Deven Bowers and Fan Wu have contributed to IPE's development
over the past several years, with Fan Wu agreeing to serve as the IPE
maintainer moving forward. Once IPE is accepted into your tree, I'll
start working with Fan to ensure he has the necessary accounts, keys,
etc. so that he can start submitting IPE pull requests to you
directly during the next merge window.
- Move the lifecycle management of the LSM blobs to the LSM framework
Management of the LSM blobs (the LSM state buffers attached to
various kernel structs, typically via a void pointer named "security"
or similar) has been mixed, some blobs were allocated/managed by
individual LSMs, others were managed by the LSM framework itself.
Starting with this pull we move management of all the LSM blobs,
minus the XFRM blob, into the framework itself, improving consistency
across LSMs, and reducing the amount of duplicated code across LSMs.
Due to some additional work required to migrate the XFRM blob, it has
been left as a todo item for a later date; from a practical
standpoint this omission should have little impact as only SELinux
provides a XFRM LSM implementation.
- Fix problems with the LSM's handling of F_SETOWN
The LSM hook for the fcntl(F_SETOWN) operation had a couple of
problems: it was racy with itself, and it was disconnected from the
associated DAC related logic in such a way that the LSM state could
be updated in cases where the DAC state would not. We fix both of
these problems by moving the security_file_set_fowner() hook into the
same section of code where the DAC attributes are updated. Not only
does this resolve the DAC/LSM synchronization issue, but as that code
block is protected by a lock, it also resolve the race condition.
- Fix potential problems with the security_inode_free() LSM hook
Due to use of RCU to protect inodes and the placement of the LSM hook
associated with freeing the inode, there is a bit of a challenge when
it comes to managing any LSM state associated with an inode. The VFS
folks are not open to relocating the LSM hook so we have to get
creative when it comes to releasing an inode's LSM state.
Traditionally we have used a single LSM callback within the hook that
is triggered when the inode is "marked for death", but not actually
released due to RCU.
Unfortunately, this causes problems for LSMs which want to take an
action when the inode's associated LSM state is actually released; so
we add an additional LSM callback, inode_free_security_rcu(), that is
called when the inode's LSM state is released in the RCU free
callback.
- Refactor two LSM hooks to better fit the LSM return value patterns
The vast majority of the LSM hooks follow the "return 0 on success,
negative values on failure" pattern, however, there are a small
handful that have unique return value behaviors which has caused
confusion in the past and makes it difficult for the BPF verifier to
properly vet BPF LSM programs. This includes patches to
convert two of these"special" LSM hooks to the common 0/-ERRNO pattern.
- Various cleanups and improvements
A handful of patches to remove redundant code, better leverage the
IS_ERR_OR_NULL() helper, add missing "static" markings, and do some
minor style fixups.
* tag 'lsm-pr-20240911' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm: (40 commits)
security: Update file_set_fowner documentation
fs: Fix file_set_fowner LSM hook inconsistencies
lsm: Use IS_ERR_OR_NULL() helper function
lsm: remove LSM_COUNT and LSM_CONFIG_COUNT
ipe: Remove duplicated include in ipe.c
lsm: replace indirect LSM hook calls with static calls
lsm: count the LSMs enabled at compile time
kernel: Add helper macros for loop unrolling
init/main.c: Initialize early LSMs after arch code, static keys and calls.
MAINTAINERS: add IPE entry with Fan Wu as maintainer
documentation: add IPE documentation
ipe: kunit test for parser
scripts: add boot policy generation program
ipe: enable support for fs-verity as a trust provider
fsverity: expose verified fsverity built-in signatures to LSMs
lsm: add security_inode_setintegrity() hook
ipe: add support for dm-verity as a trust provider
dm-verity: expose root hash digest and signature data to LSMs
block,lsm: add LSM blob and new LSM hooks for block devices
ipe: add permissive toggle
...
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Some overlayfs features require permission to read/write trusted.*
xattrs. These include redirect_dir, verity, metacopy, and data-only
layers. This patch adds additional validations at mount time to stop
overlays from mounting in certain cases where the resulting mount would
not function according to the user's expectations because they lack
permission to access trusted.* xattrs (for example, not global root.)
Similar checks in ovl_make_workdir() that disable features instead of
failing are still relevant and used in cases where the resulting mount
can still work "reasonably well." Generally, if the feature was enabled
through kernel config or module option, any mount that worked before
will still work the same; this applies to redirect_dir and metacopy. The
user must explicitly request these features in order to generate a mount
failure. Verity and data-only layers on the other hand must be explictly
requested and have no "reasonable" disabled or degraded alternative, so
mounts attempting either always fail.
"lower data-only dirs require metacopy support" moved down in case
userxattr is set, which disables metacopy.
Cc: stable@vger.kernel.org # v6.6+
Signed-off-by: Mike Baynton <mike@mbaynton.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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For upper filesystems which do not use strict ordering of persisting
metadata changes (e.g. ubifs), when overlayfs file is modified for
the first time, copy up will create a copy of the lower file and
its parent directories in the upper layer. Permission lost of the
new upper parent directory was observed during power-cut stress test.
Fix by moving the fsync call to after metadata copy to make sure that the
metadata copied up directory and files persists to disk before renaming
from tmp to final destination.
With metacopy enabled, this change will hurt performance of workloads
such as chown -R, so we keep the legacy behavior of fsync only on copyup
of data.
Link: https://lore.kernel.org/linux-unionfs/CAOQ4uxj-pOvmw1-uXR3qVdqtLjSkwcR9nVKcNU_vC10Zyf2miQ@mail.gmail.com/
Reported-and-tested-by: Fei Lv <feilv@asrmicro.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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Since commit 5679897eb104 ("vfs: make sync_filesystem return errors from
->sync_fs"), the return value from sync_fs callback can be seen in
sync_filesystem(). Thus the errseq_set opreation can be removed here.
Depends-on: commit 5679897eb104 ("vfs: make sync_filesystem return errors from ->sync_fs")
Signed-off-by: Haifeng Xu <haifeng.xu@shopee.com>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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Simplify and fix overlayfs layer parsing so the maximum of 500 layers
can be used.
* patches from https://lore.kernel.org/r/20240705011510.794025-1-chengzhihao1@huawei.com:
ovl: ovl_parse_param_lowerdir: Add missed '\n' for pr_err
ovl: fix wrong lowerdir number check for parameter Opt_lowerdir
ovl: pass string to ovl_parse_layer()
Link: https://lore.kernel.org/r/20240705011510.794025-1-chengzhihao1@huawei.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Add '\n' for pr_err in function ovl_parse_param_lowerdir(), which
ensures that error message is displayed at once.
Fixes: b36a5780cb44 ("ovl: modify layer parameter parsing")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Link: https://lore.kernel.org/r/20240705011510.794025-4-chengzhihao1@huawei.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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The max count of lowerdir is OVL_MAX_STACK[500], which is broken by
commit 37f32f526438("ovl: fix memory leak in ovl_parse_param()") for
parameter Opt_lowerdir. Since commit 819829f0319a("ovl: refactor layer
parsing helpers") and commit 24e16e385f22("ovl: add support for
appending lowerdirs one by one") added check ovl_mount_dir_check() in
function ovl_parse_param_lowerdir(), the 'ctx->nr' should be smaller
than OVL_MAX_STACK, after commit 37f32f526438("ovl: fix memory leak in
ovl_parse_param()") is applied, the 'ctx->nr' is updated before the
check ovl_mount_dir_check(), which leads the max count of lowerdir
to become 499 for parameter Opt_lowerdir.
Fix it by replacing lower layers parsing code with the existing helper
function ovl_parse_layer().
Fixes: 37f32f526438 ("ovl: fix memory leak in ovl_parse_param()")
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Link: https://lore.kernel.org/r/20240705011510.794025-3-chengzhihao1@huawei.com
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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So it can be used for parsing the Opt_lowerdir.
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Link: https://lore.kernel.org/r/20240705011510.794025-2-chengzhihao1@huawei.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
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We want the compiler to see that fdput() on empty instance
is a no-op. The emptiness check is that file reference is NULL,
while fdput() is "fput() if FDPUT_FPUT is present in flags".
The reason why fdput() on empty instance is a no-op is something
compiler can't see - it's that we never generate instances with
NULL file reference combined with non-zero flags.
It's not that hard to deal with - the real primitives behind
fdget() et.al. are returning an unsigned long value, unpacked by (inlined)
__to_fd() into the current struct file * + int. The lower bits are
used to store flags, while the rest encodes the pointer. Linus suggested
that keeping this unsigned long around with the extractions done by inlined
accessors should generate a sane code and that turns out to be the case.
Namely, turning struct fd into a struct-wrapped unsinged long, with
fd_empty(f) => unlikely(f.word == 0)
fd_file(f) => (struct file *)(f.word & ~3)
fdput(f) => if (f.word & 1) fput(fd_file(f))
ends up with compiler doing the right thing. The cost is the patch
footprint, of course - we need to switch f.file to fd_file(f) all over
the tree, and it's not doable with simple search and replace; there are
false positives, etc.
Note that the sole member of that structure is an opaque
unsigned long - all accesses should be done via wrappers and I don't
want to use a name that would invite manual casts to file pointers,
etc. The value of that member is equal either to (unsigned long)p | flags,
p being an address of some struct file instance, or to 0 for an empty fd.
For now the new predicate (fd_empty(f)) has no users; all the
existing checks have form (!fd_file(f)). We will convert to fd_empty()
use later; here we only define it (and tell the compiler that it's
unlikely to return true).
This commit only deals with representation change; there will
be followups.
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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For any changes of struct fd representation we need to
turn existing accesses to fields into calls of wrappers.
Accesses to struct fd::flags are very few (3 in linux/file.h,
1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in
explicit initializers).
Those can be dealt with in the commit converting to
new layout; accesses to struct fd::file are too many for that.
This commit converts (almost) all of f.file to
fd_file(f). It's not entirely mechanical ('file' is used as
a member name more than just in struct fd) and it does not
even attempt to distinguish the uses in pointer context from
those in boolean context; the latter will be eventually turned
into a separate helper (fd_empty()).
NOTE: mass conversion to fd_empty(), tempting as it
might be, is a bad idea; better do that piecewise in commit
that convert from fdget...() to CLASS(...).
[conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c
caught by git; fs/stat.c one got caught by git grep]
[fs/xattr.c conflict]
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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To be consistent with most LSM hooks, convert the return value of
hook inode_copy_up_xattr to 0 or a negative error code.
Before:
- Hook inode_copy_up_xattr returns 0 when accepting xattr, 1 when
discarding xattr, -EOPNOTSUPP if it does not know xattr, or any
other negative error code otherwise.
After:
- Hook inode_copy_up_xattr returns 0 when accepting xattr, *-ECANCELED*
when discarding xattr, -EOPNOTSUPP if it does not know xattr, or
any other negative error code otherwise.
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Reviewed-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
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ovl_check_encode_origin() should return a positive number if the lower
dentry is to be encoded, zero otherwise. If there's no upper layer at all
(read-only overlay), then it obviously needs to return positive.
This was broken by commit 16aac5ad1fa9 ("ovl: support encoding
non-decodable file handles"), which didn't take the lower-only
configuration into account.
Fix by checking the no-upper-layer case up-front.
Reported-and-tested-by: Youzhong Yang <youzhong@gmail.com>
Closes: https://lore.kernel.org/all/CADpNCvaBimi+zCYfRJHvCOhMih8OU0rmZkwLuh24MKKroRuT8Q@mail.gmail.com/
Fixes: 16aac5ad1fa9 ("ovl: support encoding non-decodable file handles")
Cc: <stable@vger.kernel.org> # v6.6
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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Move ovl_copy_up() call outside of ovl_want_write()/ovl_drop_write()
region, since copy up may also call ovl_want_write() resulting in recursive
locking on sb->s_writers.
Reported-and-tested-by: syzbot+85e58cdf5b3136471d4b@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/000000000000f6865106191c3e58@google.com/
Fixes: 9a87907de359 ("ovl: implement tmpfile")
Signed-off-by: Miklos Szeredi <mszeredi@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs
Pull overlayfs updates from Miklos Szeredi:
- Add tmpfile support
- Clean up include
* tag 'ovl-update-6.10' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
ovl: remove duplicate included header
ovl: remove upper umask handling from ovl_create_upper()
ovl: implement tmpfile
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