kernel/linux.git/include/linux/fs.h, branch v5.15.219

fs: don't block write during exec on pre-content watched files

2026-08-23T12:17:29+00:00

[ Upstream commit 0357ef03c94ef835bd44a0658b8edb672a9dbf51 ] Commit 2a010c412853 ("fs: don't block i_writecount during exec") removed the legacy behavior of getting ETXTBSY on attempt to open and executable file for write while it is being executed. This commit was reverted because an application that depends on this legacy behavior was broken by the change. We need to allow HSM writing into executable files while executed to fill their content on-the-fly. To that end, disable the ETXTBSY legacy behavior for files that are watched by pre-content events. This change is not expected to cause regressions with existing systems which do not have any pre-content event listeners. Signed-off-by: Amir Goldstein Acked-by: Christian Brauner Signed-off-by: Jan Kara Link: https://patch.msgid.link/20241128142532.465176-1-amir73il@gmail.com Stable-dep-of: db1856ea9196 ("binfmt_misc: restore write access when removing an entry") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

fsnotify: opt-in for permission events at file open time

2026-08-23T12:17:29+00:00

[ Upstream commit a94204f4d48e28a711b7ed10399f749286c433e3 ] Legacy inotify/fanotify listeners can add watches for events on inode, parent or mount and expect to get events (e.g. FS_MODIFY) on files that were already open at the time of setting up the watches. fanotify permission events are typically used by Anti-malware sofware, that is watching the entire mount and it is not common to have more that one Anti-malware engine installed on a system. To reduce the overhead of the fsnotify_file_perm() hooks on every file access, relax the semantics of the legacy FAN_ACCESS_PERM event to generate events only if there were *any* permission event listeners on the filesystem at the time that the file was opened. The new semantic is implemented by extending the FMODE_NONOTIFY bit into two FMODE_NONOTIFY_* bits, that are used to store a mode for which of the events types to report. This is going to apply to the new fanotify pre-content events in order to reduce the cost of the new pre-content event vfs hooks. [Thanks to Bert Karwatzki for reporting a bug in this code with CONFIG_FANOTIFY_ACCESS_PERMISSIONS disabled] Suggested-by: Linus Torvalds Link: https://lore.kernel.org/linux-fsdevel/CAHk-=wj8L=mtcRTi=NECHMGfZQgXOp_uix1YVh04fEmrKaMnXA@mail.gmail.com/ Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara Link: https://patch.msgid.link/5ea5f8e283d1edb55aa79c35187bfe344056af14.1731684329.git.josef@toxicpanda.com Stable-dep-of: db1856ea9196 ("binfmt_misc: restore write access when removing an entry") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

mm: do file ownership checks with the proper mount idmap

2026-08-23T12:17:17+00:00

[ Upstream commit e187bc02f8fa4226d62814592cf064ee4557c470 ] Ever since idmapped mounts were introduced, inode ownership checks (for side-channel protection) in mincore() and madvise(MADV_PAGEOUT) were done against the nop_mnt_idmap, which completely ignores the file's mount's idmap. This results in odd edgecases like: 1) mount/bind-mount with an idmap userA:userB:1 2) userB runs an owner_or_capable() check on file that is owned by userA on-disk/in-memory, but owned by userB after idmap translation 3) owner_or_capable() mysteriously fails as the correct idmap wasn't supplied In the case of mincore/madvise MADV_PAGEOUT, this is usually benign, because file_permission(file, MAY_WRITE) will probably succeed, as it uses the proper idmap internally, but it does not need to be the case on e.g a 0444 file where even the owner itself doesn't have permissions to write to it. Since this is clearly not trivial to get right, introduce a file_owner_or_capable() that can carry the correct semantics, and switch the various users in mm to it. The issue was found by manual code inspection & an off-list discussion with Jan Kara. Link: https://lore.kernel.org/20260625153853.913949-1-pfalcato@suse.de Fixes: 9caccd41541a ("fs: introduce MOUNT_ATTR_IDMAP") Signed-off-by: Pedro Falcato Reviewed-by: Jan Kara Reviewed-by: Christian Brauner (Amutable) Acked-by: David Hildenbrand (Arm) Cc: Al Viro Cc: Jann Horn Cc: Liam R. Howlett Cc: Matthew Wilcox (Oracle) Cc: Vlastimil Babka Cc: Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

splice, net: Add a splice_eof op to file-ops and socket-ops

2025-10-29T13:03:08+00:00

[ Upstream commit 2bfc66850952b6921b2033b09729ec59eabbc81d ] Add an optional method, ->splice_eof(), to allow splice to indicate the premature termination of a splice to struct file_operations and struct proto_ops. This is called if sendfile() or splice() encounters all of the following conditions inside splice_direct_to_actor(): (1) the user did not set SPLICE_F_MORE (splice only), and (2) an EOF condition occurred (->splice_read() returned 0), and (3) we haven't read enough to fulfill the request (ie. len > 0 still), and (4) we have already spliced at least one byte. A further patch will modify the behaviour of SPLICE_F_MORE to always be passed to the actor if either the user set it or we haven't yet read sufficient data to fulfill the request. Suggested-by: Linus Torvalds Link: https://lore.kernel.org/r/CAHk-=wh=V579PDYvkpnTobCLGczbgxpMgGmmhqiTyE34Cpi5Gg@mail.gmail.com/ Signed-off-by: David Howells Reviewed-by: Jakub Kicinski cc: Jens Axboe cc: Christoph Hellwig cc: Al Viro cc: Matthew Wilcox cc: Jan Kara cc: Jeff Layton cc: David Hildenbrand cc: Christian Brauner cc: Chuck Lever cc: Boris Pismenny cc: John Fastabend cc: linux-mm@kvack.org Signed-off-by: Jakub Kicinski Stable-dep-of: b014a4e066c5 ("tls: wait for async encrypt in case of error during latter iterations of sendmsg") Signed-off-by: Sasha Levin

mm: drop the assumption that VM_SHARED always implies writable

2025-08-28T14:24:30+00:00

[ Upstream commit e8e17ee90eaf650c855adb0a3e5e965fd6692ff1 ] Patch series "permit write-sealed memfd read-only shared mappings", v4. The man page for fcntl() describing memfd file seals states the following about F_SEAL_WRITE:- Furthermore, trying to create new shared, writable memory-mappings via mmap(2) will also fail with EPERM. With emphasis on 'writable'. In turns out in fact that currently the kernel simply disallows all new shared memory mappings for a memfd with F_SEAL_WRITE applied, rendering this documentation inaccurate. This matters because users are therefore unable to obtain a shared mapping to a memfd after write sealing altogether, which limits their usefulness. This was reported in the discussion thread [1] originating from a bug report [2]. This is a product of both using the struct address_space->i_mmap_writable atomic counter to determine whether writing may be permitted, and the kernel adjusting this counter when any VM_SHARED mapping is performed and more generally implicitly assuming VM_SHARED implies writable. It seems sensible that we should only update this mapping if VM_MAYWRITE is specified, i.e. whether it is possible that this mapping could at any point be written to. If we do so then all we need to do to permit write seals to function as documented is to clear VM_MAYWRITE when mapping read-only. It turns out this functionality already exists for F_SEAL_FUTURE_WRITE - we can therefore simply adapt this logic to do the same for F_SEAL_WRITE. We then hit a chicken and egg situation in mmap_region() where the check for VM_MAYWRITE occurs before we are able to clear this flag. To work around this, perform this check after we invoke call_mmap(), with careful consideration of error paths. Thanks to Andy Lutomirski for the suggestion! [1]:https://lore.kernel.org/all/20230324133646.16101dfa666f253c4715d965@linux-foundation.org/ [2]:https://bugzilla.kernel.org/show_bug.cgi?id=217238 This patch (of 3): There is a general assumption that VMAs with the VM_SHARED flag set are writable. If the VM_MAYWRITE flag is not set, then this is simply not the case. Update those checks which affect the struct address_space->i_mmap_writable field to explicitly test for this by introducing [vma_]is_shared_maywrite() helper functions. This remains entirely conservative, as the lack of VM_MAYWRITE guarantees that the VMA cannot be written to. Link: https://lkml.kernel.org/r/cover.1697116581.git.lstoakes@gmail.com Link: https://lkml.kernel.org/r/d978aefefa83ec42d18dfa964ad180dbcde34795.1697116581.git.lstoakes@gmail.com Signed-off-by: Lorenzo Stoakes Suggested-by: Andy Lutomirski Reviewed-by: Jan Kara Cc: Alexander Viro Cc: Christian Brauner Cc: Hugh Dickins Cc: Matthew Wilcox (Oracle) Cc: Mike Kravetz Cc: Muchun Song Signed-off-by: Andrew Morton Cc: stable@vger.kernel.org [isaacmanjarres: resolved merge conflicts due to due to refactoring that happened in upstream commit 5de195060b2e ("mm: resolve faulty mmap_region() error path behaviour")] Signed-off-by: Isaac J. Manjarres Signed-off-by: Greg Kroah-Hartman

fuse: don't truncate cached, mutated symlink

2025-04-10T12:31:51+00:00

[ Upstream commit b4c173dfbb6c78568578ff18f9e8822d7bd0e31b ] Fuse allows the value of a symlink to change and this property is exploited by some filesystems (e.g. CVMFS). It has been observed, that sometimes after changing the symlink contents, the value is truncated to the old size. This is caused by fuse_getattr() racing with fuse_reverse_inval_inode(). fuse_reverse_inval_inode() updates the fuse_inode's attr_version, which results in fuse_change_attributes() exiting before updating the cached attributes This is okay, as the cached attributes remain invalid and the next call to fuse_change_attributes() will likely update the inode with the correct values. The reason this causes problems is that cached symlinks will be returned through page_get_link(), which truncates the symlink to inode->i_size. This is correct for filesystems that don't mutate symlinks, but in this case it causes bad behavior. The solution is to just remove this truncation. This can cause a regression in a filesystem that relies on supplying a symlink larger than the file size, but this is unlikely. If that happens we'd need to make this behavior conditional. Reported-by: Laura Promberger Tested-by: Sam Lewis Signed-off-by: Miklos Szeredi Link: https://lore.kernel.org/r/20250220100258.793363-1-mszeredi@redhat.com Reviewed-by: Bernd Schubert Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

fs: move fs stat sysctls to file_table.c

2025-03-13T11:49:50+00:00

[ Upstream commit 204d5a24e15562b2816825c0f9b49d26814b77be ] kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic. We can create the sysctl dynamically on early init for fs stat to help with this clutter. This dusts off the fs stat syctls knobs and puts them into where they are declared. Link: https://lkml.kernel.org/r/20211129205548.605569-3-mcgrof@kernel.org Signed-off-by: Luis Chamberlain Cc: Al Viro Cc: Andy Shevchenko Cc: Antti Palosaari Cc: Eric Biederman Cc: Iurii Zaikin Cc: "J. Bruce Fields" Cc: Jeff Layton Cc: Kees Cook Cc: Lukas Middendorf Cc: Stephen Kitt Cc: Xiaoming Ni Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Stable-dep-of: d727935cad9f ("fs: fix proc_handler for sysctl_nr_open") Signed-off-by: Sasha Levin

fs: move inode sysctls to its own file

2025-03-13T11:49:50+00:00

[ Upstream commit 1d67fe585049d3e2448b997af78c68cbf90ada09 ] Patch series "sysctl: 4th set of kernel/sysctl cleanups". This is slimming down the fs uses of kernel/sysctl.c to the point that the next step is to just get rid of the fs base directory for it and move that elsehwere, so that next patch series starts dealing with that to demo how we can end up cleaning up a full base directory from kernel/sysctl.c, one at a time. This patch (of 9): kernel/sysctl.c is a kitchen sink where everyone leaves their dirty dishes, this makes it very difficult to maintain. To help with this maintenance let's start by moving sysctls to places where they actually belong. The proc sysctl maintainers do not want to know what sysctl knobs you wish to add for your own piece of code, we just care about the core logic. So move the inode sysctls to its own file. Since we are no longer using this outside of fs/ remove the extern declaration of its respective proc helper. We use early_initcall() as it is the earliest we can use. [arnd@arndb.de: avoid unused-variable warning] Link: https://lkml.kernel.org/r/20211203190123.874239-1-arnd@kernel.org Link: https://lkml.kernel.org/r/20211129205548.605569-1-mcgrof@kernel.org Link: https://lkml.kernel.org/r/20211129205548.605569-2-mcgrof@kernel.org Signed-off-by: Luis Chamberlain Signed-off-by: Arnd Bergmann Cc: Al Viro Cc: Kees Cook Cc: Iurii Zaikin Cc: Xiaoming Ni Cc: Eric Biederman Cc: Stephen Kitt Cc: Lukas Middendorf Cc: Antti Palosaari Cc: Andy Shevchenko Cc: Jeff Layton Cc: "J. Bruce Fields" Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Stable-dep-of: d727935cad9f ("fs: fix proc_handler for sysctl_nr_open") Signed-off-by: Sasha Levin

fs: create kiocb_{start,end}_write() helpers

2024-11-14T12:13:40+00:00

Commit ed0360bbab72b829437b67ebb2f9cfac19f59dfe upstream. aio, io_uring, cachefiles and overlayfs, all open code an ugly variant of file_{start,end}_write() to silence lockdep warnings. Create helpers for this lockdep dance so we can use the helpers in all the callers. Suggested-by: Jan Kara Signed-off-by: Amir Goldstein Reviewed-by: Jan Kara Reviewed-by: Jens Axboe Message-Id: <20230817141337.1025891-4-amir73il@gmail.com> Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

mount: warn only once about timestamp range expiration

2024-10-17T13:10:43+00:00

[ Upstream commit a128b054ce029554a4a52fc3abb8c1df8bafcaef ] Commit f8b92ba67c5d ("mount: Add mount warning for impending timestamp expiry") introduced a mount warning regarding filesystem timestamp limits, that is printed upon each writable mount or remount. This can result in a lot of unnecessary messages in the kernel log in setups where filesystems are being frequently remounted (or mounted multiple times). Avoid this by setting a superblock flag which indicates that the warning has been emitted at least once for any particular mount, as suggested in [1]. Link: https://lore.kernel.org/CAHk-=wim6VGnxQmjfK_tDg6fbHYKL4EFkmnTjVr9QnRqjDBAeA@mail.gmail.com/ [1] Link: https://lkml.kernel.org/r/20220119202934.26495-1-ailiop@suse.com Signed-off-by: Anthony Iliopoulos Reviewed-by: Christoph Hellwig Acked-by: Christian Brauner Reviewed-by: Darrick J. Wong Cc: Alexander Viro Cc: Deepa Dinamani Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Stable-dep-of: 4bcda1eaf184 ("mount: handle OOM on mnt_warn_timestamp_expiry") Signed-off-by: Sasha Levin