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configfs_get_config_item() treats a hashed dentry as proof that
sd->s_element is a live config_item. configfs_rmdir() breaks that:
simple_rmdir() leaves the dentry hashed, the last reference to the item is
dropped right after, and the dentry is only unhashed by d_delete() once
->rmdir() has returned. configfs_symlink() resolves its target holding no
lock on it, so get_target() can land in that window:
BUG: KASAN: slab-use-after-free in config_item_get+0x26/0x90
get_target fs/configfs/symlink.c:128 [inline]
configfs_symlink+0x4ab/0x1030 fs/configfs/symlink.c:185
Unhash in configfs_remove_dir(), while the item is still guaranteed to be
there. A reference obtained just before that stays harmless, as
create_link() rechecks CONFIGFS_USET_DROPPING, already set by
configfs_detach_prep(). Both configfs_unregister_subsystem() paths
d_drop() after detaching, so this only makes rmdir match them.
Reported-by: syzbot+6b16e3d085833cbf3e25@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=6b16e3d085833cbf3e25
Fixes: 7063fbf22611 ("[PATCH] configfs: User-driven configuration filesystem")
Cc: stable@vger.kernel.org
Signed-off-by: Vasileios Almpanis <vasilisalmpanis@gmail.com>
Tested-by: Breno Leitao <leitao@debian.org>
Reviewed-by: Breno Leitao <leitao@debian.org>
Link: https://patch.msgid.link/20260730093435.195441-3-vasilisalmpanis@gmail.com
Signed-off-by: Breno Leitao <leitao@debian.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull configfs updates from Al Viro:
"A couple of fixes (UAF in configfs_lookup() and really old races
introduced when lseek() on configfs directories stopped locking those
directories; impact up to and including UAF).
Fixes aside, the main result is that configfs is finally switched to
tree-in-dcache machinery. It's *not* making use of recursive removal
helpers yet, and it still does the bloody awful "build subtree in full
sight of userland, with possibility of failure halfway through and
need to unroll" that forces the locking model from hell; dealing with
that is a separate patch series, once this one is out of the way.
However, it is using DCACHE_PERSISTENT properly now. And apparmorfs is
the sole remaining user of __simple_{unlink,rmdir}() at that point"
* tag 'pull-configfs-fixed' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
create_default_group(): pass parent's dentry instead of config_group
configfs_attach_group(): drop the unused parent_item argument
configs_attach_item(): drop unused parent_item argument
configfs_create(): lift parent timestamp updates into callers
kill configfs_drop_dentry()
configfs: mark pinned dentries persistent
configfs: dentry refcount needs to be pinned only once
switch configfs_detach_{group,item}() to passing dentry
configfs_remove_dir(), detach_attrs(): switch to passing dentry
populate_attrs(): move cleanup to the sole caller
populate_group(): move cleanup on failure to the sole caller
configfs_detach_rollback(): pass configfs_dirent instead of dentry
configfs_do_depend_item(): pass configfs_dirent instead of dentry
configfs_depend_prep(): pass configfs_dirent instead of dentry
configfs_detach_prep(): pass configfs_dirent instead of dentry
configfs_mkdir(): use take_dentry_name_snapshot()
configfs: fix lockless traversals of ->s_children
configfs_lookup(): don't leave ->s_dentry dangling on failure
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the only way parent_group is used there...
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This one *was* used - for passing it to configfs_attach_item(), which
didn't use the value passed to it.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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That argument has been unused since the initial merge in 2005.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... and do *not* do it in ->lookup() case. stat foo/bar
should not update mtime of foo, TYVM...
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Fold into the only remaining user, don't bother with the timestamps
of parent - we are going to rmdir it shortly anyway, which will
override those.
Fix the locking of inode, while we are at it - updating the link
count and timestamps ought to be done with the inode locked.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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on the removal side we can (finally) get rid of __simple_unlink()
and __simple_rmdir() kludges now that dentries in question are
properly marked persistent - simple_unlink() and simple_rmdir()
will do the right thing for those.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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currently we have a weird situation where
* symlinks and roots of subtrees created by mkdir are pinned once
* subdirectories of subtrees created by mkdir are pinned twice
* roots of subtrees created by register_{group,subsystem} are pinned
twice.
It makes things harder to follow for no good reason. The goal is to
encapsulate the unbalanced dget/dput into d_{make,discard}_persisitent()
and, preferably, allow a use of simple_recursive_removal() or analogue
thereof. So let's regularize that and pin things only once.
create_default_group() and configfs_register_subsystem() don't need to
keep their reference around on success - configfs_create_dir() has pinned
the sucker already. So we can drop the reference passed to
configfs_create_dir() (via configfs_attach_group(), etc.) both on success
and on failure. On the removal side we no longer have the double references,
so we need an explicit dget() to compensate.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... and there's no need to grab/drop it, or check for NULL - none
of the callers would even get there with NULL dentry and all of
them have the sucker pinned
Note that if sd is a directory configfs_dirent, we have sd->s_element
pointing to config_item with item->ci_dentry equal to sd->s_dentry.
Which is the only reason why detach_groups() gets away with using
the latter for locking the inode and the former for removal.
Aren't redundant data structures wonderful, for obfuscation if nothing
else?
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... and deal with grabbing/dropping it in the sole caller.
After that configfs_remove_dir() becomes an unconditional call of remove_dir(),
so we can fold them together.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... where it folds with configfs_remove_dir() into a call of
configfs_detach_item(). Note that at the early failure exit
(before we'd added any children) we were not calling detach_attrs()
only because there it would've been a no-op - nothing added,
nothing there to be removed.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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... where it folds with configfs_detach_item() into a call of
configfs_detach_group().
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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same story as with configfs_detach_prep() this function is undoing.
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Again, the only thing it uses the argument for is its ->d_fsdata
and callers already have that - as the matter of fact, they are
passing ->s_dentry of that configfs_dirent, so that the function
could get it back as ->d_fsdata of that. With nothing else in
dentry even looked at...
configfs_dirent in question is a directory one - in this case those
are subdirectories of root (aka roots of "subsystem" trees).
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Again, the only thing it uses dentry for is dentry->d_fsdata; for the
recursive call the situation is the same as with configfs_detach_prep()
and the same observation about ->s_dentry->d_fsdata applies.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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The only thing it uses the argument for is its ->d_fsdata and
all callers have that already available.
Note that in the recursive call we are dealing with a (sub)directory
configfs_dirent, and for those ->s_dentry->d_fsdata points back
to configfs_dirent itself.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Note that neither ->make_group() nor ->make_item() are allowed to modify
the string passed to them - the argument is const char *.
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Having the parent directory locked protects entries from removal
by another thread, but it does *not* protect cursors from being
moved around by lseek() - or freed, for that matter.
Fixes: 6f6107640625 ("configfs: Introduce configfs_dirent_lock")
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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more idiomatic
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Normally ->s_dentry is cleared when dentry it's pointing to becomes
negative (on eviction, realistically). However, that only happens
if dentry gets to be positive in the first place; in case of inode
allocation failure dentry never becomes positive, so ->d_iput()
is not called at all.
We do part of what normally would've been done by configfs_d_iput()
(dropping the reference to configfs_dirent) manually, but we do
not clear ->s_dentry there. Sloppy as it is, it does not matter in
case of configfs_create_{dir,link}() - there configfs_dirent does
not survive dropping the sole reference to it.
However, for configfs_lookup() it *does* survive, with a dangling
pointer to soon to be freed dentry sitting it its ->s_dentry.
Subsequent getdents(2) in that directory will end up dereferencing
that pointer in order to pick the inode number. Use after free...
This is the minimal fix; the right approach is to set the linkage
between dentry and configfs_dirent only after we know that we have
an inode, but that takes more surgery and the bug had been there
since 2006, so...
Fixes: 3d0f89bb1694 ("configfs: Add permission and ownership to configfs objects") # 2.6.16-rc3
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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This was done entirely with mindless brute force, using
git grep -l '\<k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'
to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.
Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.
For the same reason the 'flex' versions will be done as a separate
conversion.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:
Single allocations: kmalloc(sizeof(TYPE), ...)
are replaced with: kmalloc_obj(TYPE, ...)
Array allocations: kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with: kmalloc_objs(TYPE, COUNT, ...)
Flex array allocations: kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with: kmalloc_flex(*PTR, FAM, COUNT, ...)
(where TYPE may also be *VAR)
The resulting allocations no longer return "void *", instead returning
"TYPE *".
Signed-off-by: Kees Cook <kees@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
Pull persistent dentry infrastructure and conversion from Al Viro:
"Some filesystems use a kinda-sorta controlled dentry refcount leak to
pin dentries of created objects in dcache (and undo it when removing
those). A reference is grabbed and not released, but it's not actually
_stored_ anywhere.
That works, but it's hard to follow and verify; among other things, we
have no way to tell _which_ of the increments is intended to be an
unpaired one. Worse, on removal we need to decide whether the
reference had already been dropped, which can be non-trivial if that
removal is on umount and we need to figure out if this dentry is
pinned due to e.g. unlink() not done. Usually that is handled by using
kill_litter_super() as ->kill_sb(), but there are open-coded special
cases of the same (consider e.g. /proc/self).
Things get simpler if we introduce a new dentry flag
(DCACHE_PERSISTENT) marking those "leaked" dentries. Having it set
claims responsibility for +1 in refcount.
The end result this series is aiming for:
- get these unbalanced dget() and dput() replaced with new primitives
that would, in addition to adjusting refcount, set and clear
persistency flag.
- instead of having kill_litter_super() mess with removing the
remaining "leaked" references (e.g. for all tmpfs files that hadn't
been removed prior to umount), have the regular
shrink_dcache_for_umount() strip DCACHE_PERSISTENT of all dentries,
dropping the corresponding reference if it had been set. After that
kill_litter_super() becomes an equivalent of kill_anon_super().
Doing that in a single step is not feasible - it would affect too many
places in too many filesystems. It has to be split into a series.
This work has really started early in 2024; quite a few preliminary
pieces have already gone into mainline. This chunk is finally getting
to the meat of that stuff - infrastructure and most of the conversions
to it.
Some pieces are still sitting in the local branches, but the bulk of
that stuff is here"
* tag 'pull-persistency' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (54 commits)
d_make_discardable(): warn if given a non-persistent dentry
kill securityfs_recursive_remove()
convert securityfs
get rid of kill_litter_super()
convert rust_binderfs
convert nfsctl
convert rpc_pipefs
convert hypfs
hypfs: swich hypfs_create_u64() to returning int
hypfs: switch hypfs_create_str() to returning int
hypfs: don't pin dentries twice
convert gadgetfs
gadgetfs: switch to simple_remove_by_name()
convert functionfs
functionfs: switch to simple_remove_by_name()
functionfs: fix the open/removal races
functionfs: need to cancel ->reset_work in ->kill_sb()
functionfs: don't bother with ffs->ref in ffs_data_{opened,closed}()
functionfs: don't abuse ffs_data_closed() on fs shutdown
convert selinuxfs
...
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Make 'ct_group_ops' const in struct config_item_type.
This allows constification of many structures which hold some function
pointers.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Reviewed-by: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/6b720cf407e8a6d30f35beb72e031b2553d1ab7e.1761390472.git.christophe.jaillet@wanadoo.fr
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
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At this point there are very few call chains that might lead to
d_make_discardable() on a dentry that hadn't been made persistent:
calls of simple_unlink() and simple_rmdir() in configfs and
apparmorfs.
Both filesystems do pin (part of) their contents in dcache, but
they are currently playing very unusual games with that. Converting
them to more usual patterns might be possible, but it's definitely
going to be a long series of changes in both cases.
For now the easiest solution is to have both stop using simple_unlink()
and simple_rmdir() - that allows to make d_make_discardable() warn
when given a non-persistent dentry.
Rather than giving them full-blown private copies (with calls of
d_make_discardable() replaced with dput()), let's pull the parts of
simple_unlink() and simple_rmdir() that deal with timestamps and link
counts into separate helpers (__simple_unlink() and __simple_rmdir()
resp.) and have those used by configfs and apparmorfs.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Use the standard error pointer macro to shorten the code and simplify.
Signed-off-by: Xichao Zhao <zhao.xichao@vivo.com>
Reviewed-by: Breno Leitao <leitao@debian.org>
Link: https://lore.kernel.org/r/20250812082709.49796-1-zhao.xichao@vivo.com
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
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Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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populate_attrs() may override failure for creating attribute files
by success for creating subsequent bin attribute files, and have
wrong return value.
Fix by creating bin attribute files under successfully creating
attribute files.
Fixes: 03607ace807b ("configfs: implement binary attributes")
Cc: stable@vger.kernel.org
Reviewed-by: Joel Becker <jlbec@evilplan.org>
Reviewed-by: Breno Leitao <leitao@debian.org>
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20250507-fix_configfs-v3-2-fe2d96de8dc4@quicinc.com
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
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Macro type_print() definition ends with semicolon, so will cause
the subsequent macro invocations end with two semicolons.
Fix by deleting the semicolon from the macro definition.
Reviewed-by: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20250507-fix_configfs-v3-1-fe2d96de8dc4@quicinc.com
Signed-off-by: Andreas Hindborg <a.hindborg@kernel.org>
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Some filesystems, such as NFS, cifs, ceph, and fuse, do not have
complete control of sequencing on the actual filesystem (e.g. on a
different server) and may find that the inode created for a mkdir
request already exists in the icache and dcache by the time the mkdir
request returns. For example, if the filesystem is mounted twice the
directory could be visible on the other mount before it is on the
original mount, and a pair of name_to_handle_at(), open_by_handle_at()
calls could instantiate the directory inode with an IS_ROOT() dentry
before the first mkdir returns.
This means that the dentry passed to ->mkdir() may not be the one that
is associated with the inode after the ->mkdir() completes. Some
callers need to interact with the inode after the ->mkdir completes and
they currently need to perform a lookup in the (rare) case that the
dentry is no longer hashed.
This lookup-after-mkdir requires that the directory remains locked to
avoid races. Planned future patches to lock the dentry rather than the
directory will mean that this lookup cannot be performed atomically with
the mkdir.
To remove this barrier, this patch changes ->mkdir to return the
resulting dentry if it is different from the one passed in.
Possible returns are:
NULL - the directory was created and no other dentry was used
ERR_PTR() - an error occurred
non-NULL - this other dentry was spliced in
This patch only changes file-systems to return "ERR_PTR(err)" instead of
"err" or equivalent transformations. Subsequent patches will make
further changes to some file-systems to return a correct dentry.
Not all filesystems reliably result in a positive hashed dentry:
- NFS, cifs, hostfs will sometimes need to perform a lookup of
the name to get inode information. Races could result in this
returning something different. Note that this lookup is
non-atomic which is what we are trying to avoid. Placing the
lookup in filesystem code means it only happens when the filesystem
has no other option.
- kernfs and tracefs leave the dentry negative and the ->revalidate
operation ensures that lookup will be called to correctly populate
the dentry. This could be fixed but I don't think it is important
to any of the users of vfs_mkdir() which look at the dentry.
The recommendation to use
d_drop();d_splice_alias()
is ugly but fits with current practice. A planned future patch will
change this.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: NeilBrown <neilb@suse.de>
Link: https://lore.kernel.org/r/20250227013949.536172-2-neilb@suse.de
Signed-off-by: Christian Brauner <brauner@kernel.org>
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As the size of a directory increases item creation slows down.
Optimizing access to s_children removes this bottleneck.
dirents are already pinned into the cache, there is no need to scan the
s_children list looking for duplicate Items. The configfs_dirent_exists
check is moved to a location where it is called only during subsystem
initialization.
d_lookup will only need to call configfs_lookup in the case where the
item in question is not pinned to dcache. The only items not pinned to
dcache are attributes. These are placed at the front of the s_children
list, whilst pinned items are inserted at the back. configfs_lookup
stops scanning when it encounters the first pinned entry in s_children.
The assumption of the above optimizations is that there will be few
attributes, but potentially many Items in a given directory.
Signed-off-by: Seamus Connor <sconnor@purestorage.com>
Reviewed-by: Joel Becker <jlbec@evilplan.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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In order to support dynamic decisions as to whether an attribute should be
created, add a callback that returns a bool to indicate whether the
attribute should be displayed. If no callback is registered, the attribute
is displayed by default.
Co-developed-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Tom Lendacky <thomas.lendacky@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/e555c8740a263fab9f83b2cbb44da1af49a2813c.1717600736.git.thomas.lendacky@amd.com
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There are three copies of the same dt_type helper sprinkled around the
tree. Convert them to use the common fs_umode_to_dtype function instead,
which has the added advantage of properly returning DT_UNKNOWN when
given a mode that contains an unrecognized type.
Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Phillip Potter <phil@philpotter.co.uk>
Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Message-Id: <20230330104144.75547-1-jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
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Convert to struct mnt_idmap.
Last cycle we merged the necessary infrastructure in
256c8aed2b42 ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.
Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.
Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.
Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
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kmemleak reported memory leaks in configfs_create_dir():
unreferenced object 0xffff888009f6af00 (size 192):
comm "modprobe", pid 3777, jiffies 4295537735 (age 233.784s)
backtrace:
kmem_cache_alloc (mm/slub.c:3250 mm/slub.c:3256 mm/slub.c:3263 mm/slub.c:3273)
new_fragment (./include/linux/slab.h:600 fs/configfs/dir.c:163)
configfs_register_subsystem (fs/configfs/dir.c:1857)
basic_write (drivers/hwtracing/stm/p_basic.c:14) stm_p_basic
do_one_initcall (init/main.c:1296)
do_init_module (kernel/module/main.c:2455)
...
unreferenced object 0xffff888003ba7180 (size 96):
comm "modprobe", pid 3777, jiffies 4295537735 (age 233.784s)
backtrace:
kmem_cache_alloc (mm/slub.c:3250 mm/slub.c:3256 mm/slub.c:3263 mm/slub.c:3273)
configfs_new_dirent (./include/linux/slab.h:723 fs/configfs/dir.c:194)
configfs_make_dirent (fs/configfs/dir.c:248)
configfs_create_dir (fs/configfs/dir.c:296)
configfs_attach_group.isra.28 (fs/configfs/dir.c:816 fs/configfs/dir.c:852)
configfs_register_subsystem (fs/configfs/dir.c:1881)
basic_write (drivers/hwtracing/stm/p_basic.c:14) stm_p_basic
do_one_initcall (init/main.c:1296)
do_init_module (kernel/module/main.c:2455)
...
This is because the refcount is not correct in configfs_make_dirent().
For normal stage, the refcount is changing as:
configfs_register_subsystem()
configfs_create_dir()
configfs_make_dirent()
configfs_new_dirent() # set s_count = 1
dentry->d_fsdata = configfs_get(sd); # s_count = 2
...
configfs_unregister_subsystem()
configfs_remove_dir()
remove_dir()
configfs_remove_dirent() # s_count = 1
dput() ...
*dentry_unlink_inode()*
configfs_d_iput() # s_count = 0, release
However, if we failed in configfs_create():
configfs_register_subsystem()
configfs_create_dir()
configfs_make_dirent() # s_count = 2
...
configfs_create() # fail
->out_remove:
configfs_remove_dirent(dentry)
configfs_put(sd) # s_count = 1
return PTR_ERR(inode);
There is no inode in the error path, so the configfs_d_iput() is lost
and makes sd and fragment memory leaked.
To fix this, when we failed in configfs_create(), manually call
configfs_put(sd) to keep the refcount correct.
Fixes: 7063fbf22611 ("[PATCH] configfs: User-driven configuration filesystem")
Signed-off-by: Chen Zhongjin <chenzhongjin@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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When configfs_register_subsystem() or configfs_unregister_subsystem()
is executing link_group() or unlink_group(),
it is possible that two processes add or delete list concurrently.
Some unfortunate interleavings of them can cause kernel panic.
One of cases is:
A --> B --> C --> D
A <-- B <-- C <-- D
delete list_head *B | delete list_head *C
--------------------------------|-----------------------------------
configfs_unregister_subsystem | configfs_unregister_subsystem
unlink_group | unlink_group
unlink_obj | unlink_obj
list_del_init | list_del_init
__list_del_entry | __list_del_entry
__list_del | __list_del
// next == C |
next->prev = prev |
| next->prev = prev
prev->next = next |
| // prev == B
| prev->next = next
Fix this by adding mutex when calling link_group() or unlink_group(),
but parent configfs_subsystem is NULL when config_item is root.
So I create a mutex configfs_subsystem_mutex.
Fixes: 7063fbf22611 ("[PATCH] configfs: User-driven configuration filesystem")
Signed-off-by: ChenXiaoSong <chenxiaosong2@huawei.com>
Signed-off-by: Laibin Qiu <qiulaibin@huawei.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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Commit 49246466a989 ("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 in pseudo filesystems, convert d_delete() calls
to d_drop() (see commit 46c46f8df9aa ("devpts_pty_kill(): don't bother
with d_delete()") and move the fsnotify hook after d_drop().
Add a missing fsnotify_unlink() hook in nfsdfs that was found during
the audit of fsnotify hooks in pseudo filesystems.
Note that the fsnotify hooks in simple_recursive_removal() follow
d_invalidate(), so they require no change.
Link: https://lore.kernel.org/r/20220120215305.282577-2-amir73il@gmail.com
Reported-by: Ivan Delalande <colona@arista.com>
Link: https://lore.kernel.org/linux-fsdevel/YeNyzoDM5hP5LtGW@visor/
Fixes: 49246466a989 ("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>
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When configfs_lookup() is executing list_for_each_entry(),
it is possible that configfs_dir_lseek() is calling list_del().
Some unfortunate interleavings of them can cause a kernel NULL
pointer dereference error
Thread 1 Thread 2
//configfs_dir_lseek() //configfs_lookup()
list_del(&cursor->s_sibling);
list_for_each_entry(sd, ...)
Fix this by grabbing configfs_dirent_lock in configfs_lookup()
while iterating ->s_children.
Signed-off-by: Sishuai Gong <sishuai@purdue.edu>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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This makes it more clear what gets added to the dcache and prepares
for an additional locking fix.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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Return the error directly instead of using a goto.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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Just like most other file systems: get the simple checks out of the
way first.
Signed-off-by: Christoph Hellwig <hch@lst.de>
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The section "19) Editor modelines and other cruft" in
Documentation/process/coding-style.rst clearly says, "Do not include any
of these in source files."
I recently receive a patch to explicitly add a new one.
Let's do treewide cleanups, otherwise some people follow the existing code
and attempt to upstream their favoriate editor setups.
It is even nicer if scripts/checkpatch.pl can check it.
If we like to impose coding style in an editor-independent manner, I think
editorconfig (patch [1]) is a saner solution.
[1] https://lore.kernel.org/lkml/20200703073143.423557-1-danny@kdrag0n.dev/
Link: https://lkml.kernel.org/r/20210324054457.1477489-1-masahiroy@kernel.org
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Miguel Ojeda <ojeda@kernel.org> [auxdisplay]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.
As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.
Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
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Add explanation for 'frag' parameter to avoid kernel-doc issue:
fs/configfs/dir.c:277: warning: Function parameter or member 'frag' not
described in 'configfs_create_dir'
Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Christoph Hellwig <hch@lst.de>
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Drop duplicated words {the, that} in comments.
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Joel Becker <jlbec@evilplan.org>
Cc: Christoph Hellwig <hch@lst.de>
Link: https://lkml.kernel.org/r/20200811021826.25032-1-rdunlap@infradead.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.
[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through
Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
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configfs_rmdir() invokes configfs_get_config_item(), which returns a
reference of the specified config_item object to "parent_item" with
increased refcnt.
When configfs_rmdir() returns, local variable "parent_item" becomes
invalid, so the refcount should be decreased to keep refcount balanced.
The reference counting issue happens in one exception handling path of
configfs_rmdir(). When down_write_killable() fails, the function forgets
to decrease the refcnt increased by configfs_get_config_item(), causing
a refcnt leak.
Fix this issue by calling config_item_put() when down_write_killable()
fails.
Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn>
Signed-off-by: Xin Tan <tanxin.ctf@gmail.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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Get rid of the callback, deal with that and dentry in callers
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
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