kernel/linux.git/fs/overlayfs/dir.c, branch linux-7.1.y

Merge tag 'pull-dcache-busy-wait' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2026-04-21T14:30:44+00:00

Pull dcache busy loop updates from Al Viro: "Fix livelocks in shrink_dcache_tree() If shrink_dcache_tree() finds a dentry in the middle of being killed by another thread, it has to wait until the victim finishes dying, gets detached from the tree and ceases to pin its parent. The way we used to deal with that amounted to busy-wait; unfortunately, it's not just inefficient but can lead to reliably reproducible hard livelocks. Solved by having shrink_dentry_tree() attach a completion to such dentry, with dentry_unlist() calling complete() on all objects attached to it. With a bit of care it can be done without growing struct dentry or adding overhead in normal case" * tag 'pull-dcache-busy-wait' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: get rid of busy-waiting in shrink_dcache_tree() dcache.c: more idiomatic "positives are not allowed" sanity checks struct dentry: make ->d_u anonymous for_each_alias(): helper macro for iterating through dentries of given inode

Merge tag 'lsm-pr-20260410' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm

2026-04-13T22:17:28+00:00

Pull LSM updates from Paul Moore: "We only have five patches in the LSM tree, but three of the five are for an important bugfix relating to overlayfs and the mmap() and mprotect() access controls for LSMs. Highlights below: - Fix problems with the mmap() and mprotect() LSM hooks on overlayfs As we are dealing with problems both in mmap() and mprotect() there are essentially two components to this fix, spread across three patches with all marked for stable. The simplest portion of the fix is the creation of a new LSM hook, security_mmap_backing_file(), that is used to enforce LSM mmap() access controls on backing files in the stacked/overlayfs case. The existing security_mmap_file() does not have visibility past the user file. You can see from the associated SELinux hook callback the code is fairly straightforward. The mprotect() fix is a bit more complicated as there is no way in the mprotect() code path to inspect both the user and backing files, and bolting on a second file reference to vm_area_struct wasn't really an option. The solution taken here adds a LSM security blob and associated hooks to the backing_file struct that LSMs can use to capture and store relevant information from the user file. While the necessary SELinux information is relatively small, a single u32, I expect other LSMs to require more than that, and a dedicated backing_file LSM blob provides a storage mechanism without negatively impacting other filesystems. I want to note that other LSMs beyond SELinux have been involved in the discussion of the fixes presented here and they are working on their own related changes using these new hooks, but due to other issues those patches will be coming at a later date. - Use kstrdup_const()/kfree_const() for securityfs symlink targets - Resolve a handful of kernel-doc warnings in cred.h" * tag 'lsm-pr-20260410' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm: selinux: fix overlayfs mmap() and mprotect() access checks lsm: add backing_file LSM hooks fs: prepare for adding LSM blob to backing_file securityfs: use kstrdup_const() to manage symlink targets cred: fix kernel-doc warnings in cred.h

lsm: add backing_file LSM hooks

2026-04-03T20:53:50+00:00

Stacked filesystems such as overlayfs do not currently provide the necessary mechanisms for LSMs to properly enforce access controls on the mmap() and mprotect() operations. In order to resolve this gap, a LSM security blob is being added to the backing_file struct and the following new LSM hooks are being created: security_backing_file_alloc() security_backing_file_free() security_mmap_backing_file() The first two hooks are to manage the lifecycle of the LSM security blob in the backing_file struct, while the third provides a new mmap() access control point for the underlying backing file. It is also expected that LSMs will likely want to update their security_file_mprotect() callback to address issues with their mprotect() controls, but that does not require a change to the security_file_mprotect() LSM hook. There are a three other small changes to support these new LSM hooks: * Pass the user file associated with a backing file down to alloc_empty_backing_file() so it can be included in the security_backing_file_alloc() hook. * Add getter and setter functions for the backing_file struct LSM blob as the backing_file struct remains private to fs/file_table.c. * Constify the file struct field in the LSM common_audit_data struct to better support LSMs that need to pass a const file struct pointer into the common LSM audit code. Thanks to Arnd Bergmann for identifying the missing EXPORT_SYMBOL_GPL() and supplying a fixup. Cc: stable@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org Cc: linux-unionfs@vger.kernel.org Cc: linux-erofs@lists.ozlabs.org Reviewed-by: Amir Goldstein Reviewed-by: Serge Hallyn Reviewed-by: Christian Brauner Signed-off-by: Paul Moore

for_each_alias(): helper macro for iterating through dentries of given inode

2026-04-02T07:45:02+00:00

Most of the places using d_alias are loops iterating through all aliases for given inode; introduce a helper macro (for_each_alias(dentry, inode)) and convert open-coded instances of such loop to it. They are easier to read that way and it reduces the noise on the next steps. You _must_ hold inode->i_lock over that thing. Signed-off-by: Al Viro

ovl: change ovl_create_real() to get a new lock when re-opening created file.

2026-03-09T08:43:03+00:00

When ovl_create_real() is used to create a file on the upper filesystem it needs to return the resulting dentry - positive and hashed. It is usually the case the that dentry passed to the create function (e.g. vfs_create()) will be suitable but this is not guaranteed. The filesystem may unhash that dentry forcing a repeat lookup next time the name is wanted. So ovl_create_real() must be (and is) aware of this and prepared to perform that lookup to get a hash positive dentry. This is currently done under that same directory lock that provided exclusion for the create. Proposed changes to locking will make this not possible - as the name, rather than the directory, will be locked. The new APIs provided for lookup and locking do not and cannot support this pattern. The lock isn't needed. ovl_create_real() can drop the lock and then get a new lock for the lookup - then check that the lookup returned the correct inode. In a well-behaved configuration where the upper filesystem is not being modified by a third party, this will always work reliably, and if there are separate modification it will fail cleanly. So change ovl_create_real() to drop the lock and call ovl_start_creating_upper() to find the correct dentry. Note that start_creating doesn't fail if the name already exists. The lookup previously used the name from newdentry which was guaranteed to be stable because the parent directory was locked. As we now drop the lock we lose that guarantee. As newdentry is unhashed it is unlikely for the name to change, but safest not to depend on that. So the expected name is now passed in to ovl_create_real() and that is used. This removes the only remaining use of ovl_lookup_upper, so it is removed. Reviewed-by: Amir Goldstein Signed-off-by: NeilBrown Link: https://patch.msgid.link/20260224222542.3458677-13-neilb@ownmail.net Signed-off-by: Christian Brauner

ovl: pass name buffer to ovl_start_creating_temp()

2026-03-09T08:43:03+00:00

Now ovl_start_creating_temp() is passed a buffer in which to store the temp name. This will be useful in a future patch were ovl_create_real() will need access to that name. Reviewed-by: Amir Goldstein Signed-off-by: NeilBrown Link: https://patch.msgid.link/20260224222542.3458677-12-neilb@ownmail.net Signed-off-by: Christian Brauner

ovl: pass original credentials, not mounter credentials during create

2025-12-06T00:16:20+00:00

When creating new files the security layer expects the original credentials to be passed. When cleaning up the code this was accidently changed to pass the mounter's credentials by relying on current->cred which is already overriden at this point. Pass the original credentials directly. Reported-by: Ondrej Mosnacek Reported-by: Paul Moore Fixes: e566bff96322 ("ovl: port ovl_create_or_link() to new ovl_override_creator_creds") Link: https://lore.kernel.org/CAFqZXNvL1ciLXMhHrnoyBmQu1PAApH41LkSWEhrcvzAAbFij8Q@mail.gmail.com Signed-off-by: Christian Brauner Tested-by: Ondrej Mosnacek Reviewed-by: Amir Goldstein Signed-off-by: Linus Torvalds

Merge tag 'vfs-6.19-rc1.ovl' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-12-02T00:31:21+00:00

Pull overlayfs cred guard conversion from Christian Brauner: "This converts all of overlayfs to use credential guards, eliminating manual credential management throughout the filesystem. Credential guard conversion: - Convert all of overlayfs to use credential guards, replacing the manual ovl_override_creds()/ovl_revert_creds() pattern with scoped guards. This makes credential handling visually explicit and eliminates a class of potential bugs from mismatched override/revert calls. (1) Basic credential guard (with_ovl_creds) (2) Creator credential guard (ovl_override_creator_creds): Introduced a specialized guard for file creation operations that handles the two-phase credential override (mounter credentials, then fs{g,u}id override). The new pattern is much clearer: with_ovl_creds(dentry->d_sb) { scoped_class(prepare_creds_ovl, cred, dentry, inode, mode) { if (IS_ERR(cred)) return PTR_ERR(cred); /* creation operations */ } } (3) Copy-up credential guard (ovl_cu_creds): Introduced a specialized guard for copy-up operations, simplifying the previous struct ovl_cu_creds helper and associated functions. Ported ovl_copy_up_workdir() and ovl_copy_up_tmpfile() to this pattern. Cleanups: - Remove ovl_revert_creds() after all callers converted to guards - Remove struct ovl_cu_creds and associated functions - Drop ovl_setup_cred_for_create() after conversion - Refactor ovl_fill_super(), ovl_lookup(), ovl_iterate(), ovl_rename() for cleaner credential guard scope - Introduce struct ovl_renamedata to simplify rename handling - Don't override credentials for ovl_check_whiteouts() (unnecessary) - Remove unneeded semicolon" * tag 'vfs-6.19-rc1.ovl' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (54 commits) ovl: remove unneeded semicolon ovl: remove struct ovl_cu_creds and associated functions ovl: port ovl_copy_up_tmpfile() to cred guard ovl: mark *_cu_creds() as unused temporarily ovl: port ovl_copy_up_workdir() to cred guard ovl: add copy up credential guard ovl: drop ovl_setup_cred_for_create() ovl: port ovl_create_or_link() to new ovl_override_creator_creds cleanup guard ovl: mark ovl_setup_cred_for_create() as unused temporarily ovl: reflow ovl_create_or_link() ovl: port ovl_create_tmpfile() to new ovl_override_creator_creds cleanup guard ovl: add ovl_override_creator_creds cred guard ovl: remove ovl_revert_creds() ovl: port ovl_fill_super() to cred guard ovl: refactor ovl_fill_super() ovl: port ovl_lower_positive() to cred guard ovl: port ovl_lookup() to cred guard ovl: refactor ovl_lookup() ovl: port ovl_copyfile() to cred guard ovl: port ovl_rename() to cred guard ...

Merge tag 'vfs-6.19-rc1.directory.locking' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2025-12-02T00:13:46+00:00

Pull directory locking updates from Christian Brauner: "This contains the work to add centralized APIs for directory locking operations. This series is part of a larger effort to change directory operation locking to allow multiple concurrent operations in a directory. The ultimate goal is to lock the target dentry(s) rather than the whole parent directory. To help with changing the locking protocol, this series centralizes locking and lookup in new helper functions. The helpers establish a pattern where it is the dentry that is being locked and unlocked (currently the lock is held on dentry->d_parent->d_inode, but that can change in the future). This also changes vfs_mkdir() to unlock the parent on failure, as well as dput()ing the dentry. This allows end_creating() to only require the target dentry (which may be IS_ERR() after vfs_mkdir()), not the parent" * tag 'vfs-6.19-rc1.directory.locking' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: nfsd: fix end_creating() conversion VFS: introduce end_creating_keep() VFS: change vfs_mkdir() to unlock on failure. ecryptfs: use new start_creating/start_removing APIs Add start_renaming_two_dentries() VFS/ovl/smb: introduce start_renaming_dentry() VFS/nfsd/ovl: introduce start_renaming() and end_renaming() VFS: add start_creating_killable() and start_removing_killable() VFS: introduce start_removing_dentry() smb/server: use end_removing_noperm for for target of smb2_create_link() VFS: introduce start_creating_noperm() and start_removing_noperm() VFS/nfsd/cachefiles/ovl: introduce start_removing() and end_removing() VFS/nfsd/cachefiles/ovl: add start_creating() and end_creating() VFS: tidy up do_unlinkat() VFS: introduce start_dirop() and end_dirop() debugfs: rename end_creating() to debugfs_end_creating()

ovl: remove unneeded semicolon

2025-11-28T10:05:52+00:00

Remove unnecessary semicolons reported by Coccinelle/coccicheck and the semantic patch at scripts/coccinelle/misc/semicolon.cocci. Signed-off-by: Chen Ni Fixed: 7ab96df840e60 ("VFS/nfsd/cachefiles/ovl: add start_creating() and end_creating()") Signed-off-by: Amir Goldstein Signed-off-by: Christian Brauner