Commit 7d6899fb69 ("ovl: fsync after metadata copy-up") was done to
fix durability of overlayfs copy up on an upper filesystem which does
not enforce ordering on storing of metadata changes (e.g. ubifs).
In an earlier revision of the regressing commit by Lei Lv, the metadata
fsync behavior was opt-in via a new "fsync=strict" mount option.
We were hoping that the opt-in mount option could be avoided, so the
change was only made to depend on metacopy=off, in the hope of not
hurting performance of metadata heavy workloads, which are more likely
to be using metacopy=on.
This hope was proven wrong by a performance regression report from Google
COS workload after upgrade to kernel 6.12.
This is an adaptation of Lei's original "fsync=strict" mount option
to the existing upstream code.
The new mount option is mutually exclusive with the "volatile" mount
option, so the latter is now an alias to the "fsync=volatile" mount
option.
Reported-by: Chenglong Tang <chenglongtang@google.com>
Closes: https://lore.kernel.org/linux-unionfs/CAOdxtTadAFH01Vui1FvWfcmQ8jH1O45owTzUcpYbNvBxnLeM7Q@mail.gmail.com/
Link: https://lore.kernel.org/linux-unionfs/CAOQ4uxgKC1SgjMWre=fUb00v8rxtd6sQi-S+dxR8oDzAuiGu8g@mail.gmail.com/
Fixes: 7d6899fb69 ("ovl: fsync after metadata copy-up")
Depends: 50e638beb6 ("ovl: Use str_on_off() helper in ovl_show_options()")
Cc: stable@vger.kernel.org # v6.12+
Signed-off-by: Fei Lv <feilv@asrmicro.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
They will become unused in the next patch and we'll drop them after the
conversion is finished together with the struct. This keeps the changes
small and reviewable.
Link: https://patch.msgid.link/20251114-work-ovl-cred-guard-copyup-v1-3-ea3fb15cf427@kernel.org
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Bring in the directory locking changes as they touch overlayfs in a
pretty substantial way and we are about to change the credential
override semantics quite substantially as well.
Signed-off-by: Christian Brauner <brauner@kernel.org>
vfs_mkdir() already drops the reference to the dentry on failure but it
leaves the parent locked.
This complicates end_creating() which needs to unlock the parent even
though the dentry is no longer available.
If we change vfs_mkdir() to unlock on failure as well as releasing the
dentry, we can remove the "parent" arg from end_creating() and simplify
the rules for calling it.
Note that cachefiles_get_directory() can choose to substitute an error
instead of actually calling vfs_mkdir(), for fault injection. In that
case it needs to call end_creating(), just as vfs_mkdir() now does on
error.
ovl_create_real() will now unlock on error. So the conditional
end_creating() after the call is removed, and end_creating() is called
internally on error.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-15-neilb@ownmail.net
Signed-off-by: Christian Brauner <brauner@kernel.org>
Several callers perform a rename on a dentry they already have, and only
require lookup for the target name. This includes smb/server and a few
different places in overlayfs.
start_renaming_dentry() performs the required lookup and takes the
required lock using lock_rename_child()
It is used in three places in overlayfs and in ksmbd_vfs_rename().
In the ksmbd case, the parent of the source is not important - the
source must be renamed from wherever it is. So start_renaming_dentry()
allows rd->old_parent to be NULL and only checks it if it is non-NULL.
On success rd->old_parent will be the parent of old_dentry with an extra
reference taken. Other start_renaming function also now take the extra
reference and end_renaming() now drops this reference as well.
ovl_lookup_temp(), ovl_parent_lock(), and ovl_parent_unlock() are
all removed as they are no longer needed.
OVL_TEMPNAME_SIZE and ovl_tempname() are now declared in overlayfs.h so
that ovl_check_rename_whiteout() can access them.
ovl_copy_up_workdir() now always cleans up on error.
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-12-neilb@ownmail.net
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
start_creating() is similar to simple_start_creating() but is not so
simple.
It takes a qstr for the name, includes permission checking, and does NOT
report an error if the name already exists, returning a positive dentry
instead.
This is currently used by nfsd, cachefiles, and overlayfs.
end_creating() is called after the dentry has been used.
end_creating() drops the reference to the dentry as it is generally no
longer needed. This is exactly the first section of end_creating_path()
so that function is changed to call the new end_creating()
These calls help encapsulate locking rules so that directory locking can
be changed.
Occasionally this change means that the parent lock is held for a
shorter period of time, for example in cachefiles_commit_tmpfile().
As this function now unlocks after an unlink and before the following
lookup, it is possible that the lookup could again find a positive
dentry, so a while loop is introduced there.
In overlayfs the ovl_lookup_temp() function has ovl_tempname()
split out to be used in ovl_start_creating_temp(). The other use
of ovl_lookup_temp() is preparing for a rename. When rename handling
is updated, ovl_lookup_temp() will be removed.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://patch.msgid.link/20251113002050.676694-5-neilb@ownmail.net
Tested-by: syzbot@syzkaller.appspotmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
This reverts commit 474b155adf.
This patch caused regression in ioctl_setflags(). Underlying filesystems
use EOPNOTSUPP to indicate that flag is not supported. This error is
also gets converted in ioctl_setflags(). Therefore, for unsupported
flags error changed from EOPNOSUPP to ENOIOCTLCMD.
Link: https://lore.kernel.org/linux-xfs/a622643f-1585-40b0-9441-cf7ece176e83@kernel.org/
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-f_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull file->f_path constification from Al Viro:
"Only one thing was modifying ->f_path of an opened file - acct(2).
Massaging that away and constifying a bunch of struct path * arguments
in functions that might be given &file->f_path ends up with the
situation where we can turn ->f_path into an anon union of const
struct path f_path and struct path __f_path, the latter modified only
in a few places in fs/{file_table,open,namei}.c, all for struct file
instances that are yet to be opened"
* tag 'pull-f_path' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (23 commits)
Have cc(1) catch attempts to modify ->f_path
kernel/acct.c: saner struct file treatment
configfs:get_target() - release path as soon as we grab configfs_item reference
apparmor/af_unix: constify struct path * arguments
ovl_is_real_file: constify realpath argument
ovl_sync_file(): constify path argument
ovl_lower_dir(): constify path argument
ovl_get_verity_digest(): constify path argument
ovl_validate_verity(): constify {meta,data}path arguments
ovl_ensure_verity_loaded(): constify datapath argument
ksmbd_vfs_set_init_posix_acl(): constify path argument
ksmbd_vfs_inherit_posix_acl(): constify path argument
ksmbd_vfs_kern_path_unlock(): constify path argument
ksmbd_vfs_path_lookup_locked(): root_share_path can be const struct path *
check_export(): constify path argument
export_operations->open(): constify path argument
rqst_exp_get_by_name(): constify path argument
nfs: constify path argument of __vfs_getattr()
bpf...d_path(): constify path argument
done_path_create(): constify path argument
...
To keep ovl's inodes consistent with their real inodes, create a new
mask for inode file attributes that needs to be copied. Add the
S_CASEFOLD flag as part of the flags that need to be copied along with
the other file attributes.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: André Almeida <andrealmeid@igalia.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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Merge tag 'vfs-6.17-rc1.fileattr' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull fileattr updates from Christian Brauner:
"This introduces the new file_getattr() and file_setattr() system calls
after lengthy discussions.
Both system calls serve as successors and extensible companions to
the FS_IOC_FSGETXATTR and FS_IOC_FSSETXATTR system calls which have
started to show their age in addition to being named in a way that
makes it easy to conflate them with extended attribute related
operations.
These syscalls allow userspace to set filesystem inode attributes on
special files. One of the usage examples is the XFS quota projects.
XFS has project quotas which could be attached to a directory. All new
inodes in these directories inherit project ID set on parent
directory.
The project is created from userspace by opening and calling
FS_IOC_FSSETXATTR on each inode. This is not possible for special
files such as FIFO, SOCK, BLK etc. Therefore, some inodes are left
with empty project ID. Those inodes then are not shown in the quota
accounting but still exist in the directory. This is not critical but
in the case when special files are created in the directory with
already existing project quota, these new inodes inherit extended
attributes. This creates a mix of special files with and without
attributes. Moreover, special files with attributes don't have a
possibility to become clear or change the attributes. This, in turn,
prevents userspace from re-creating quota project on these existing
files.
In addition, these new system calls allow the implementation of
additional attributes that we couldn't or didn't want to fit into the
legacy ioctls anymore"
* tag 'vfs-6.17-rc1.fileattr' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
fs: tighten a sanity check in file_attr_to_fileattr()
tree-wide: s/struct fileattr/struct file_kattr/g
fs: introduce file_getattr and file_setattr syscalls
fs: prepare for extending file_get/setattr()
fs: make vfs_fileattr_[get|set] return -EOPNOTSUPP
selinux: implement inode_file_[g|s]etattr hooks
lsm: introduce new hooks for setting/getting inode fsxattr
fs: split fileattr related helpers into separate file
The only remaining user of ovl_cleanup() is ovl_cleanup_locked(), so we
no longer need both.
This patch renames ovl_cleanup() to ovl_cleanup_locked() and makes it
static.
ovl_cleanup_unlocked() is renamed to ovl_cleanup().
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/20250716004725.1206467-22-neil@brown.name
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
In ovl_copy_up_workdir() unlock immediately after the rename. There is
nothing else in the function that needs the lock.
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/20250716004725.1206467-5-neil@brown.name
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
ovl currently locks a directory or two and then performs multiple actions
in one or both directories. This is incompatible with proposed changes
which will lock just the dentry of objects being acted on.
This patch moves calls to ovl_create_temp() out of the locked regions and
has it take and release the relevant lock itself.
The lock that was taken before this function was called is now taken
after. This means that any code between where the lock was taken and
ovl_create_temp() is now unlocked. This necessitates the use of
ovl_cleanup_unlocked() and the creation of ovl_lookup_upper_unlocked().
These will be used more widely in future patches.
Now that the file is created before the lock is taken for rename, we
need to ensure the parent wasn't changed before the lock was gained.
ovl_lock_rename_workdir() is changed to optionally receive the dentries
that will be involved in the rename. If either is present but has the
wrong parent, an error is returned.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/20250716004725.1206467-4-neil@brown.name
Signed-off-by: Christian Brauner <brauner@kernel.org>
ovl_copy_up_workdir() currently take a rename lock on two directories,
then use the lock to both create a file in one directory, perform a
rename, and possibly unlink the file for cleanup. This is incompatible
with proposed changes which will lock just the dentry of objects being
acted on.
This patch moves the call to ovl_create_index() earlier in
ovl_copy_up_workdir() to before the lock is taken.
ovl_create_index() then takes the required lock only when needed.
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/20250716004725.1206467-3-neil@brown.name
Signed-off-by: Christian Brauner <brauner@kernel.org>
If ovl_copy_up_data() fails the error is not immediately handled but the
code continues on to call ovl_start_write() and lock_rename(),
presumably because both of these locks are needed for the cleanup.
Only then (if the lock was successful) is the error checked.
This makes the code a little hard to follow and could be fragile.
This patch changes to handle the error after the ovl_start_write()
(which cannot fail, so there aren't multiple errors to deail with). A
new ovl_cleanup_unlocked() is created which takes the required directory
lock. This will be used extensively in later patches.
In general we need to check the parent is still correct after taking the
lock (as ovl_copy_up_workdir() does after a successful lock_rename()) so
that is included in ovl_cleanup_unlocked() using new ovl_parent_lock()
and ovl_parent_unlock() calls (it is planned to move this API into VFS code
eventually, though in a slightly different form).
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/20250716004725.1206467-2-neil@brown.name
Reviewed-by: Amir Goldstein <amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Now that we expose struct file_attr as our uapi struct rename all the
internal struct to struct file_kattr to clearly communicate that it is a
kernel internal struct. This is similar to struct mount_{k}attr and
others.
Link: https://lore.kernel.org/20250703-restlaufzeit-baurecht-9ed44552b481@brauner
Signed-off-by: Christian Brauner <brauner@kernel.org>
Future patches will add new syscalls which use these functions. As
this interface won't be used for ioctls only, the EOPNOSUPP is more
appropriate return code.
This patch converts return code from ENOIOCTLCMD to EOPNOSUPP for
vfs_fileattr_get and vfs_fileattr_set. To save old behavior translate
EOPNOSUPP back for current users - overlayfs, encryptfs and fs/ioctl.c.
Signed-off-by: Andrey Albershteyn <aalbersh@kernel.org>
Link: https://lore.kernel.org/20250630-xattrat-syscall-v6-4-c4e3bc35227b@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
all users of 'struct renamedata' have the dentry for the old and new
directories, and often have no use for the inode except to store it in
the renamedata.
This patch changes struct renamedata to hold the dentry, rather than
the inode, for the old and new directories, and changes callers to
match. The names are also changed from a _dir suffix to _parent. This
is consistent with other usage in namei.c and elsewhere.
This results in the removal of several local variables and several
dereferences of ->d_inode at the cost of adding ->d_inode dereferences
to vfs_rename().
Acked-by: Miklos Szeredi <miklos@szeredi.hu>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: NeilBrown <neil@brown.name>
Link: https://lore.kernel.org/174977089072.608730.4244531834577097454@noble.neil.brown.name
Signed-off-by: Christian Brauner <brauner@kernel.org>
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: b07d5cc93e ("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>
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 16aac5ad1f ("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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Merge tag 'ovl-update-6.13' of 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
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>
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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Merge tag 'ovl-update-6.12' of 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
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>
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>
Copying up xattrs is solely based on the security xattr name. For finer
granularity add a dentry parameter to the security_inode_copy_up_xattr
hook definition, allowing decisions to be based on the xattr content as
well.
Co-developed-by: Mimi Zohar <zohar@linux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
Acked-by: Amir Goldstein <amir73il@gmail.com>
Acked-by: Paul Moore <paul@paul-moore.com> (LSM,SELinux)
Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
syzbot hit an assertion in copy up data loop which looks like it is
the result of a lower file whose size is being changed underneath
overlayfs.
This type of use case is documented to cause undefined behavior, so
returning EIO error for the copy up makes sense, but it should not be
causing a WARN_ON assertion.
Reported-and-tested-by: syzbot+3abd99031b42acf367ef@syzkaller.appspotmail.com
Fixes: ca7ab48240 ("ovl: add permission hooks outside of do_splice_direct()")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
commit dfad37051a ("remap_range: move permission hooks out of
do_clone_file_range()") moved the permission hooks from
do_clone_file_range() out to its caller vfs_clone_file_range(),
but left all the fast sanity checks in do_clone_file_range().
This makes the expensive security hooks be called in situations
that they would not have been called before (e.g. fs does not support
clone).
The only reason for the do_clone_file_range() helper was that overlayfs
did not use to be able to call vfs_clone_file_range() from copy up
context with sb_writers lock held. However, since commit c63e56a4a6
("ovl: do not open/llseek lower file with upper sb_writers held"),
overlayfs just uses an open coded version of vfs_clone_file_range().
Merge_clone_file_range() into vfs_clone_file_range(), restoring the
original order of checks as it was before the regressing commit and adapt
the overlayfs code to call vfs_clone_file_range() before the permission
hooks that were added by commit ca7ab48240 ("ovl: add permission hooks
outside of do_splice_direct()").
Note that in the merge of do_clone_file_range(), the file_start_write()
context was reduced to cover ->remap_file_range() without holding it
over the permission hooks, which was the reason for doing the regressing
commit in the first place.
Reported-and-tested-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202401312229.eddeb9a6-oliver.sang@intel.com
Fixes: dfad37051a ("remap_range: move permission hooks out of do_clone_file_range()")
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20240202102258.1582671-1-amir73il@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
broken in 6.5; we really can't lock two unrelated directories
without holding ->s_vfs_rename_mutex first and in case of
same-parent rename of a subdirectory 6.5 ends up doing just
that.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull rename updates from Al Viro:
"Fix directory locking scheme on rename
This was broken in 6.5; we really can't lock two unrelated directories
without holding ->s_vfs_rename_mutex first and in case of same-parent
rename of a subdirectory 6.5 ends up doing just that"
* tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
rename(): avoid a deadlock in the case of parents having no common ancestor
kill lock_two_inodes()
rename(): fix the locking of subdirectories
f2fs: Avoid reading renamed directory if parent does not change
ext4: don't access the source subdirectory content on same-directory rename
ext2: Avoid reading renamed directory if parent does not change
udf_rename(): only access the child content on cross-directory rename
ocfs2: Avoid touching renamed directory if parent does not change
reiserfs: Avoid touching renamed directory if parent does not change
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Merge tag 'ovl-update-6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs
Pull overlayfs updates from Amir Goldstein:
"This is a very small update with no bug fixes and no new features.
The larger update of overlayfs for this cycle, the re-factoring of
overlayfs code into generic backing_file helpers, was already merged
via Christian.
Summary:
- Simplify/clarify some code
No bug fixes here, just some changes following questions from Al
about overlayfs code that could be a little more simple to follow.
- Overlayfs documentation style fixes
Mainly fixes for ReST formatting suggested by documentation
developers"
* tag 'ovl-update-6.8' of git://git.kernel.org/pub/scm/linux/kernel/git/overlayfs/vfs:
overlayfs.rst: fix ReST formatting
overlayfs.rst: use consistent feature names
ovl: initialize ovl_copy_up_ctx.destname inside ovl_do_copy_up()
ovl: remove redundant ofs->indexdir member
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Merge tag 'vfs-6.8.rw' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs
Pull vfs rw updates from Christian Brauner:
"This contains updates from Amir for read-write backing file helpers
for stacking filesystems such as overlayfs:
- Fanotify is currently in the process of introducing pre content
events. Roughly, a new permission event will be added indicating
that it is safe to write to the file being accessed. These events
are used by hierarchical storage managers to e.g., fill the content
of files on first access.
During that work we noticed that our current permission checking is
inconsistent in rw_verify_area() and remap_verify_area().
Especially in the splice code permission checking is done multiple
times. For example, one time for the whole range and then again for
partial ranges inside the iterator.
In addition, we mostly do permission checking before we call
file_start_write() except for a few places where we call it after.
For pre-content events we need such permission checking to be done
before file_start_write(). So this is a nice reason to clean this
all up.
After this series, all permission checking is done before
file_start_write().
As part of this cleanup we also massaged the splice code a bit. We
got rid of a few helpers because we are alredy drowning in special
read-write helpers. We also cleaned up the return types for splice
helpers.
- Introduce generic read-write helpers for backing files. This lifts
some overlayfs code to common code so it can be used by the FUSE
passthrough work coming in over the next cycles. Make Amir and
Miklos the maintainers for this new subsystem of the vfs"
* tag 'vfs-6.8.rw' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (30 commits)
fs: fix __sb_write_started() kerneldoc formatting
fs: factor out backing_file_mmap() helper
fs: factor out backing_file_splice_{read,write}() helpers
fs: factor out backing_file_{read,write}_iter() helpers
fs: prepare for stackable filesystems backing file helpers
fsnotify: optionally pass access range in file permission hooks
fsnotify: assert that file_start_write() is not held in permission hooks
fsnotify: split fsnotify_perm() into two hooks
fs: use splice_copy_file_range() inline helper
splice: return type ssize_t from all helpers
fs: use do_splice_direct() for nfsd/ksmbd server-side-copy
fs: move file_start_write() into direct_splice_actor()
fs: fork splice_file_range() from do_splice_direct()
fs: create {sb,file}_write_not_started() helpers
fs: create file_write_started() helper
fs: create __sb_write_started() helper
fs: move kiocb_start_write() into vfs_iocb_iter_write()
fs: move permission hook out of do_iter_read()
fs: move permission hook out of do_iter_write()
fs: move file_start_write() into vfs_iter_write()
...
syzbot excercised the forbidden practice of moving the workdir under
lowerdir while overlayfs is mounted and tripped a dentry reference leak.
Fixes: c63e56a4a6 ("ovl: do not open/llseek lower file with upper sb_writers held")
Reported-and-tested-by: syzbot+8608bb4553edb8c78f41@syzkaller.appspotmail.com
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
The callers of do_splice_direct() hold file_start_write() on the output
file.
This may cause file permission hooks to be called indirectly on an
overlayfs lower layer, which is on the same filesystem of the output
file and could lead to deadlock with fanotify permission events.
To fix this potential deadlock, move file_start_write() from the callers
into the direct_splice_actor(), so file_start_write() will not be held
while splicing from the input file.
Suggested-by: Josef Bacik <josef@toxicpanda.com>
Link: https://lore.kernel.org/r/20231128214258.GA2398475@perftesting/
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231130141624.3338942-3-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
... and fix the directory locking documentation and proof of correctness.
Holding ->s_vfs_rename_mutex *almost* prevents ->d_parent changes; the
case where we really don't want it is splicing the root of disconnected
tree to somewhere.
In other words, ->s_vfs_rename_mutex is sufficient to stabilize "X is an
ancestor of Y" only if X and Y are already in the same tree. Otherwise
it can go from false to true, and one can construct a deadlock on that.
Make lock_two_directories() report an error in such case and update the
callers of lock_rename()/lock_rename_child() to handle such errors.
And yes, such conditions are not impossible to create ;-/
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
The main callers of do_splice_direct() also call rw_verify_area() for
the entire range that is being copied, e.g. by vfs_copy_file_range()
or do_sendfile() before calling do_splice_direct().
The only caller that does not have those checks for entire range is
ovl_copy_up_file(). In preparation for removing the checks inside
do_splice_direct(), add rw_verify_area() call in ovl_copy_up_file().
For extra safety, perform minimal sanity checks from rw_verify_area()
for non negative offsets also in the copy up do_splice_direct() loop
without calling the file permission hooks.
This is needed for fanotify "pre content" events.
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231122122715.2561213-2-amir73il@gmail.com
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
The ->destname member of struct ovl_copy_up_ctx is initialized inside
ovl_copy_up_one() to ->d_name of the overlayfs dentry being copied up
and then it may be overridden by index name inside ovl_do_copy_up().
ovl_inode_lock() in ovl_copy_up_start() and ovl_copy_up() in ovl_rename()
effectively stabilze ->d_name of the overlayfs dentry being copied up,
but ovl_inode_lock() is not held when ->d_name is being read.
It is not a correctness bug, because if ovl_do_copy_up() races with
ovl_rename() and ctx.destname is freed, we will not end up calling
ovl_do_copy_up() with the dead name reference.
The code becomes much easier to understand and to document if the
initialization of c->destname is always done inside ovl_do_copy_up(),
either to the index entry name, or to the overlay dentry ->d_name.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
When lower fs is a nested overlayfs, calling encode_fh() on a lower
directory dentry may trigger copy up and take sb_writers on the upper fs
of the lower nested overlayfs.
The lower nested overlayfs may have the same upper fs as this overlayfs,
so nested sb_writers lock is illegal.
Move all the callers that encode lower fh to before ovl_want_write().
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
overlayfs file open (ovl_maybe_lookup_lowerdata) and overlay file llseek
take the ovl_inode_lock, without holding upper sb_writers.
In case of nested lower overlay that uses same upper fs as this overlay,
lockdep will warn about (possibly false positive) circular lock
dependency when doing open/llseek of lower ovl file during copy up with
our upper sb_writers held, because the locking ordering seems reverse to
the locking order in ovl_copy_up_start():
- lower ovl_inode_lock
- upper sb_writers
Let the copy up "transaction" keeps an elevated mnt write count on upper
mnt, but leaves taking upper sb_writers to lower level helpers only when
they actually need it. This allows to avoid holding upper sb_writers
during lower file open/llseek and prevents the lockdep warning.
Minimizing the scope of upper sb_writers during copy up is also needed
for fixing another possible deadlocks by a following patch.
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Make the locking order of ovl_inode_lock() strictly between the two
vfs stacked layers, i.e.:
- ovl vfs locks: sb_writers, inode_lock, ...
- ovl_inode_lock
- upper vfs locks: sb_writers, inode_lock, ...
To that effect, move ovl_want_write() into the helpers ovl_nlink_start()
and ovl_copy_up_start which currently take the ovl_inode_lock() after
ovl_want_write().
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
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Merge tag 'v6.6-rc4.vfs.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs
Pull vfs fixes from Christian Brauner:
"This contains the usual miscellaneous fixes and cleanups for vfs and
individual fses:
Fixes:
- Revert ki_pos on error from buffered writes for direct io fallback
- Add missing documentation for block device and superblock handling
for changes merged this cycle
- Fix reiserfs flexible array usage
- Ensure that overlayfs sets ctime when setting mtime and atime
- Disable deferred caller completions with overlayfs writes until
proper support exists
Cleanups:
- Remove duplicate initialization in pipe code
- Annotate aio kioctx_table with __counted_by"
* tag 'v6.6-rc4.vfs.fixes' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs:
overlayfs: set ctime when setting mtime and atime
ntfs3: put resources during ntfs_fill_super()
ovl: disable IOCB_DIO_CALLER_COMP
porting: document superblock as block device holder
porting: document new block device opening order
fs/pipe: remove duplicate "offset" initializer
fs-writeback: do not requeue a clean inode having skipped pages
aio: Annotate struct kioctx_table with __counted_by
direct_write_fallback(): on error revert the ->ki_pos update from buffered write
reiserfs: Replace 1-element array with C99 style flex-array
Nathan reported that he was seeing the new warning in
setattr_copy_mgtime pop when starting podman containers. Overlayfs is
trying to set the atime and mtime via notify_change without also
setting the ctime.
POSIX states that when the atime and mtime are updated via utimes() that
we must also update the ctime to the current time. The situation with
overlayfs copy-up is analogies, so add ATTR_CTIME to the bitmask.
notify_change will fill in the value.
Reported-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Tested-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Acked-by: Amir Goldstein <amir73il@gmail.com>
Message-Id: <20230913-ctime-v1-1-c6bc509cbc27@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
