kernel/linux.git/fs/ioctl.c, branch v6.12.80

introduce fd_file(), convert all accessors to it.

2024-08-13T02:00:43+00:00

For any changes of struct fd representation we need to turn existing accesses to fields into calls of wrappers. Accesses to struct fd::flags are very few (3 in linux/file.h, 1 in net/socket.c, 3 in fs/overlayfs/file.c and 3 more in explicit initializers). Those can be dealt with in the commit converting to new layout; accesses to struct fd::file are too many for that. This commit converts (almost) all of f.file to fd_file(f). It's not entirely mechanical ('file' is used as a member name more than just in struct fd) and it does not even attempt to distinguish the uses in pointer context from those in boolean context; the latter will be eventually turned into a separate helper (fd_empty()). NOTE: mass conversion to fd_empty(), tempting as it might be, is a bad idea; better do that piecewise in commit that convert from fdget...() to CLASS(...). [conflicts in fs/fhandle.c, kernel/bpf/syscall.c, mm/memcontrol.c caught by git; fs/stat.c one got caught by git grep] [fs/xattr.c conflict] Reviewed-by: Christian Brauner Signed-off-by: Al Viro

fs/ioctl: Add a comment to keep the logic in sync with LSM policies

2024-05-13T04:58:35+00:00

Landlock's IOCTL support needs to partially replicate the list of IOCTLs from do_vfs_ioctl(). The list of commands implemented in do_vfs_ioctl() should be kept in sync with Landlock's IOCTL policies. Suggested-by: Paul Moore Suggested-by: Mickaël Salaün Signed-off-by: Günther Noack Link: https://lore.kernel.org/r/20240419161122.2023765-12-gnoack@google.com Signed-off-by: Mickaël Salaün

fs: Return ENOTTY directly if FS_IOC_GETUUID or FS_IOC_GETFSSYSFSPATH fail

2024-04-09T10:03:49+00:00

These IOCTL commands should be implemented by setting attributes on the superblock, rather than in the IOCTL hooks in struct file_operations. By returning -ENOTTY instead of -ENOIOCTLCMD, we instruct the fs/ioctl.c logic to return -ENOTTY immediately, rather than attempting to call f_op->unlocked_ioctl() or f_op->compat_ioctl() as a fallback. Why this is safe: Before this change, fs/ioctl.c would unsuccessfully attempt calling the IOCTL hooks, and then return -ENOTTY. By returning -ENOTTY directly, we return the same error code immediately, but save ourselves the fallback attempt. Motivation: This simplifies the logic for these IOCTL commands and lets us reason about the side effects of these IOCTLs more easily. It will be possible to permit these IOCTLs under LSM IOCTL policies, without having to worry about them getting dispatched to problematic device drivers (which sometimes do work before looking at the IOCTL command number). Link: https://lore.kernel.org/all/cnwpkeovzbumhprco7q2c2y6zxzmxfpwpwe3tyy6c3gg2szgqd@vfzjaw5v5imr/ Cc: Kent Overstreet Cc: Christian Brauner Cc: Jan Kara Cc: Dave Chinner Cc: Darrick J. Wong Cc: Theodore Ts'o Cc: Josef Bacik Signed-off-by: Günther Noack Link: https://lore.kernel.org/r/20240405214040.101396-2-gnoack@google.com Acked-by: Kent Overstreet Signed-off-by: Christian Brauner

fs: add FS_IOC_GETFSSYSFSPATH

2024-02-12T12:13:59+00:00

Add a new ioctl for getting the sysfs name of a filesystem - the path under /sys/fs. This is going to let us standardize exporting data from sysfs across filesystems, e.g. time stats. The returned path will always be of the form "$FSTYP/$SYSFS_IDENTIFIER", where the sysfs identifier may be a UUID (for bcachefs) or a device name (xfs). Cc: Christian Brauner Cc: Jan Kara Cc: Dave Chinner Cc: Darrick J. Wong Cc: Theodore Ts'o Cc: Josef Bacik Signed-off-by: Kent Overstreet Link: https://lore.kernel.org/r/20240207025624.1019754-6-kent.overstreet@linux.dev Signed-off-by: Christian Brauner

fs: FS_IOC_GETUUID

2024-02-08T20:20:11+00:00

Add a new generic ioctls for querying the filesystem UUID. These are lifted versions of the ext4 ioctls, with one change: we're not using a flexible array member, because UUIDs will never be more than 16 bytes. This patch adds a generic implementation of FS_IOC_GETFSUUID, which reads from super_block->s_uuid. We're not lifting SETFSUUID from ext4 - that can be done on offline filesystems by the people who need it, trying to do it online is just asking for too much trouble. Cc: Christian Brauner Cc: Jan Kara Cc: Dave Chinner Cc: Darrick J. Wong Cc: Theodore Ts'o Cc: linux-fsdevel@vger.kernel.org Signed-off-by: Kent Overstreet Link: https://lore.kernel.org/r/20240207025624.1019754-4-kent.overstreet@linux.dev Signed-off-by: Christian Brauner

lsm: new security_file_ioctl_compat() hook

2023-12-24T20:48:03+00:00

Some ioctl commands do not require ioctl permission, but are routed to other permissions such as FILE_GETATTR or FILE_SETATTR. This routing is done by comparing the ioctl cmd to a set of 64-bit flags (FS_IOC_*). However, if a 32-bit process is running on a 64-bit kernel, it emits 32-bit flags (FS_IOC32_*) for certain ioctl operations. These flags are being checked erroneously, which leads to these ioctl operations being routed to the ioctl permission, rather than the correct file permissions. This was also noted in a RED-PEN finding from a while back - "/* RED-PEN how should LSM module know it's handling 32bit? */". This patch introduces a new hook, security_file_ioctl_compat(), that is called from the compat ioctl syscall. All current LSMs have been changed to support this hook. Reviewing the three places where we are currently using security_file_ioctl(), it appears that only SELinux needs a dedicated compat change; TOMOYO and SMACK appear to be functional without any change. Cc: stable@vger.kernel.org Fixes: 0b24dcb7f2f7 ("Revert "selinux: simplify ioctl checking"") Signed-off-by: Alfred Piccioni Reviewed-by: Stephen Smalley [PM: subject tweak, line length fixes, and alignment corrections] Signed-off-by: Paul Moore

Merge tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

2023-08-28T18:04:18+00:00

Pull superblock updates from Christian Brauner: "This contains the super rework that was ready for this cycle. The first part changes the order of how we open block devices and allocate superblocks, contains various cleanups, simplifications, and a new mechanism to wait on superblock state changes. This unblocks work to ultimately limit the number of writers to a block device. Jan has already scheduled follow-up work that will be ready for v6.7 and allows us to restrict the number of writers to a given block device. That series builds on this work right here. The second part contains filesystem freezing updates. Overview: The generic superblock changes are rougly organized as follows (ignoring additional minor cleanups): (1) Removal of the bd_super member from struct block_device. This was a very odd back pointer to struct super_block with unclear rules. For all relevant places we have other means to get the same information so just get rid of this. (2) Simplify rules for superblock cleanup. Roughly, everything that is allocated during fs_context initialization and that's stored in fs_context->s_fs_info needs to be cleaned up by the fs_context->free() implementation before the superblock allocation function has been called successfully. After sget_fc() returned fs_context->s_fs_info has been transferred to sb->s_fs_info at which point sb->kill_sb() if fully responsible for cleanup. Adhering to these rules means that cleanup of sb->s_fs_info in fill_super() is to be avoided as it's brittle and inconsistent. Cleanup shouldn't be duplicated between sb->put_super() as sb->put_super() is only called if sb->s_root has been set aka when the filesystem has been successfully born (SB_BORN). That complexity should be avoided. This also means that block devices are to be closed in sb->kill_sb() instead of sb->put_super(). More details in the lower section. (3) Make it possible to lookup or create a superblock before opening block devices There's a subtle dependency on (2) as some filesystems did rely on fill_super() to be called in order to correctly clean up sb->s_fs_info. All these filesystems have been fixed. (4) Switch most filesystem to follow the same logic as the generic mount code now does as outlined in (3). (5) Use the superblock as the holder of the block device. We can now easily go back from block device to owning superblock. (6) Export and extend the generic fs_holder_ops and use them as holder ops everywhere and remove the filesystem specific holder ops. (7) Call from the block layer up into the filesystem layer when the block device is removed, allowing to shut down the filesystem without risk of deadlocks. (8) Get rid of get_super(). We can now easily go back from the block device to owning superblock and can call up from the block layer into the filesystem layer when the device is removed. So no need to wade through all registered superblock to find the owning superblock anymore" Link: https://lore.kernel.org/lkml/20230824-prall-intakt-95dbffdee4a0@brauner/ * tag 'v6.6-vfs.super' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (47 commits) super: use higher-level helper for {freeze,thaw} super: wait until we passed kill super super: wait for nascent superblocks super: make locking naming consistent super: use locking helpers fs: simplify invalidate_inodes fs: remove get_super block: call into the file system for ioctl BLKFLSBUF block: call into the file system for bdev_mark_dead block: consolidate __invalidate_device and fsync_bdev block: drop the "busy inodes on changed media" log message dasd: also call __invalidate_device when setting the device offline amiflop: don't call fsync_bdev in FDFMTBEG floppy: call disk_force_media_change when changing the format block: simplify the disk_force_media_change interface nbd: call blk_mark_disk_dead in nbd_clear_sock_ioctl xfs use fs_holder_ops for the log and RT devices xfs: drop s_umount over opening the log and RT devices ext4: use fs_holder_ops for the log device ext4: drop s_umount over opening the log device ...

fs: Fix kernel-doc warnings

2023-08-19T10:12:12+00:00

These have a variety of causes and a corresponding variety of solutions. Signed-off-by: "Matthew Wilcox (Oracle)" Message-Id: <20230818200824.2720007-1-willy@infradead.org> Signed-off-by: Christian Brauner

fs: distinguish between user initiated freeze and kernel initiated freeze

2023-07-17T16:00:09+00:00

Userspace can freeze a filesystem using the FIFREEZE ioctl or by suspending the block device; this state persists until userspace thaws the filesystem with the FITHAW ioctl or resuming the block device. Since commit 18e9e5104fcd ("Introduce freeze_super and thaw_super for the fsfreeze ioctl") we only allow the first freeze command to succeed. The kernel may decide that it is necessary to freeze a filesystem for its own internal purposes, such as suspends in progress, filesystem fsck activities, or quiescing a device prior to removal. Userspace thaw commands must never break a kernel freeze, and kernel thaw commands shouldn't undo userspace's freeze command. Introduce a couple of freeze holder flags and wire it into the sb_writers state. One kernel and one userspace freeze are allowed to coexist at the same time; the filesystem will not thaw until both are lifted. I wonder if the f2fs/gfs2 code should be using a kernel freeze here, but for now we'll use FREEZE_HOLDER_USERSPACE to preserve existing behaviors. Cc: mcgrof@kernel.org Cc: jack@suse.cz Cc: hch@infradead.org Cc: ruansy.fnst@fujitsu.com Signed-off-by: Darrick J. Wong Reviewed-by: Christoph Hellwig Reviewed-by: Dave Chinner Reviewed-by: Jan Kara

fs: port inode_owner_or_capable() to mnt_idmap

2023-01-19T08:24:29+00:00

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 Reviewed-by: Christoph Hellwig Signed-off-by: Christian Brauner (Microsoft)