kernel/linux.git/fs/xattr.c, branch v6.6.133

xattr: switch to CLASS(fd)

2026-04-06T07:55:59+00:00

[ Upstream commit a71874379ec8c6e788a61d71b3ad014a8d9a5c08 ] Reviewed-by: Christian Brauner Signed-off-by: Al Viro Link: https://lore.kernel.org/all/20241002012230.4174585-1-viro@zeniv.linux.org.uk/ [ Neither `fd_file` nor `fd_empty` are available in 6.6.y, so the changes to the check are dropped. Kept the minor formatting change. ] Signed-off-by: Tomasz Kramkowski Tested-by: Barry K. Nathan Signed-off-by: Greg Kroah-Hartman

Revert "xattr: switch to CLASS(fd)"

2026-04-06T07:55:58+00:00

This reverts commit 5a1e865e51063d6c56f673ec8ad4b6604321b455 which is commit a71874379ec8c6e788a61d71b3ad014a8d9a5c08 upstream. A backporting mistake erroneously removed file descriptor checks for `fgetxattr`, `flistxattr`, `fremovexattr`, and `fsetxattr` which lead to kernel panics when those functions were called from userspace with a file descriptor which did not reference an open file. Reported-by: Brad Spengler Closes: https://x.com/spendergrsec/status/2040049852793450561 Cc: Alva Lan Cc: Al Viro Signed-off-by: Tomasz Kramkowski Tested-by: Barry K. Nathan Signed-off-by: Greg Kroah-Hartman

xattr: switch to CLASS(fd)

2026-04-02T11:07:30+00:00

[ Upstream commit a71874379ec8c6e788a61d71b3ad014a8d9a5c08 ] Reviewed-by: Christian Brauner Signed-off-by: Al Viro [ Only switch to CLASS(fd) in v6.6.y for fd_empty() was introduced in commit 88a2f6468d01 ("struct fd: representation change") in 6.12. ] Signed-off-by: Alva Lan Signed-off-by: Greg Kroah-Hartman

fs/xattr.c: fix simple_xattr_list()

2025-06-27T10:08:57+00:00

[ Upstream commit 800d0b9b6a8b1b354637b4194cc167ad1ce2bdd3 ] commit 8b0ba61df5a1 ("fs/xattr.c: fix simple_xattr_list to always include security.* xattrs") failed to reset err after the call to security_inode_listsecurity(), which returns the length of the returned xattr name. This results in simple_xattr_list() incorrectly returning this length even if a POSIX acl is also set on the inode. Reported-by: Collin Funk Closes: https://lore.kernel.org/selinux/8734ceal7q.fsf@gmail.com/ Reported-by: Paul Eggert Closes: https://bugzilla.redhat.com/show_bug.cgi?id=2369561 Fixes: 8b0ba61df5a1 ("fs/xattr.c: fix simple_xattr_list to always include security.* xattrs") Signed-off-by: Stephen Smalley Link: https://lore.kernel.org/20250605165116.2063-1-stephen.smalley.work@gmail.com Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

fs/xattr.c: fix simple_xattr_list to always include security.* xattrs

2025-05-22T12:12:11+00:00

[ Upstream commit 8b0ba61df5a1c44e2b3cf683831a4fc5e24ea99d ] The vfs has long had a fallback to obtain the security.* xattrs from the LSM when the filesystem does not implement its own listxattr, but shmem/tmpfs and kernfs later gained their own xattr handlers to support other xattrs. Unfortunately, as a side effect, tmpfs and kernfs-based filesystems like sysfs no longer return the synthetic security.* xattr names via listxattr unless they are explicitly set by userspace or initially set upon inode creation after policy load. coreutils has recently switched from unconditionally invoking getxattr for security.* for ls -Z via libselinux to only doing so if listxattr returns the xattr name, breaking ls -Z of such inodes. Before: $ getfattr -m.* /run/initramfs $ getfattr -m.* /sys/kernel/fscaps $ setfattr -n user.foo /run/initramfs $ getfattr -m.* /run/initramfs user.foo After: $ getfattr -m.* /run/initramfs security.selinux $ getfattr -m.* /sys/kernel/fscaps security.selinux $ setfattr -n user.foo /run/initramfs $ getfattr -m.* /run/initramfs security.selinux user.foo Link: https://lore.kernel.org/selinux/CAFqZXNtF8wDyQajPCdGn=iOawX4y77ph0EcfcqcUUj+T87FKyA@mail.gmail.com/ Link: https://lore.kernel.org/selinux/20250423175728.3185-2-stephen.smalley.work@gmail.com/ Signed-off-by: Stephen Smalley Link: https://lore.kernel.org/20250424152822.2719-1-stephen.smalley.work@gmail.com Fixes: b09e0fa4b4ea66266058ee ("tmpfs: implement generic xattr support") Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

vfs: Fix potential circular locking through setxattr() and removexattr()

2024-09-12T09:11:38+00:00

[ Upstream commit c3a5e3e872f3688ae0dc57bb78ca633921d96a91 ] When using cachefiles, lockdep may emit something similar to the circular locking dependency notice below. The problem appears to stem from the following: (1) Cachefiles manipulates xattrs on the files in its cache when called from ->writepages(). (2) The setxattr() and removexattr() system call handlers get the name (and value) from userspace after taking the sb_writers lock, putting accesses of the vma->vm_lock and mm->mmap_lock inside of that. (3) The afs filesystem uses a per-inode lock to prevent multiple revalidation RPCs and in writeback vs truncate to prevent parallel operations from deadlocking against the server on one side and local page locks on the other. Fix this by moving the getting of the name and value in {get,remove}xattr() outside of the sb_writers lock. This also has the minor benefits that we don't need to reget these in the event of a retry and we never try to take the sb_writers lock in the event we can't pull the name and value into the kernel. Alternative approaches that might fix this include moving the dispatch of a write to the cache off to a workqueue or trying to do without the validation lock in afs. Note that this might also affect other filesystems that use netfslib and/or cachefiles. ====================================================== WARNING: possible circular locking dependency detected 6.10.0-build2+ #956 Not tainted ------------------------------------------------------ fsstress/6050 is trying to acquire lock: ffff888138fd82f0 (mapping.invalidate_lock#3){++++}-{3:3}, at: filemap_fault+0x26e/0x8b0 but task is already holding lock: ffff888113f26d18 (&vma->vm_lock->lock){++++}-{3:3}, at: lock_vma_under_rcu+0x165/0x250 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #4 (&vma->vm_lock->lock){++++}-{3:3}: __lock_acquire+0xaf0/0xd80 lock_acquire.part.0+0x103/0x280 down_write+0x3b/0x50 vma_start_write+0x6b/0xa0 vma_link+0xcc/0x140 insert_vm_struct+0xb7/0xf0 alloc_bprm+0x2c1/0x390 kernel_execve+0x65/0x1a0 call_usermodehelper_exec_async+0x14d/0x190 ret_from_fork+0x24/0x40 ret_from_fork_asm+0x1a/0x30 -> #3 (&mm->mmap_lock){++++}-{3:3}: __lock_acquire+0xaf0/0xd80 lock_acquire.part.0+0x103/0x280 __might_fault+0x7c/0xb0 strncpy_from_user+0x25/0x160 removexattr+0x7f/0x100 __do_sys_fremovexattr+0x7e/0xb0 do_syscall_64+0x9f/0x100 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #2 (sb_writers#14){.+.+}-{0:0}: __lock_acquire+0xaf0/0xd80 lock_acquire.part.0+0x103/0x280 percpu_down_read+0x3c/0x90 vfs_iocb_iter_write+0xe9/0x1d0 __cachefiles_write+0x367/0x430 cachefiles_issue_write+0x299/0x2f0 netfs_advance_write+0x117/0x140 netfs_write_folio.isra.0+0x5ca/0x6e0 netfs_writepages+0x230/0x2f0 afs_writepages+0x4d/0x70 do_writepages+0x1e8/0x3e0 filemap_fdatawrite_wbc+0x84/0xa0 __filemap_fdatawrite_range+0xa8/0xf0 file_write_and_wait_range+0x59/0x90 afs_release+0x10f/0x270 __fput+0x25f/0x3d0 __do_sys_close+0x43/0x70 do_syscall_64+0x9f/0x100 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #1 (&vnode->validate_lock){++++}-{3:3}: __lock_acquire+0xaf0/0xd80 lock_acquire.part.0+0x103/0x280 down_read+0x95/0x200 afs_writepages+0x37/0x70 do_writepages+0x1e8/0x3e0 filemap_fdatawrite_wbc+0x84/0xa0 filemap_invalidate_inode+0x167/0x1e0 netfs_unbuffered_write_iter+0x1bd/0x2d0 vfs_write+0x22e/0x320 ksys_write+0xbc/0x130 do_syscall_64+0x9f/0x100 entry_SYSCALL_64_after_hwframe+0x76/0x7e -> #0 (mapping.invalidate_lock#3){++++}-{3:3}: check_noncircular+0x119/0x160 check_prev_add+0x195/0x430 __lock_acquire+0xaf0/0xd80 lock_acquire.part.0+0x103/0x280 down_read+0x95/0x200 filemap_fault+0x26e/0x8b0 __do_fault+0x57/0xd0 do_pte_missing+0x23b/0x320 __handle_mm_fault+0x2d4/0x320 handle_mm_fault+0x14f/0x260 do_user_addr_fault+0x2a2/0x500 exc_page_fault+0x71/0x90 asm_exc_page_fault+0x22/0x30 other info that might help us debug this: Chain exists of: mapping.invalidate_lock#3 --> &mm->mmap_lock --> &vma->vm_lock->lock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- rlock(&vma->vm_lock->lock); lock(&mm->mmap_lock); lock(&vma->vm_lock->lock); rlock(mapping.invalidate_lock#3); *** DEADLOCK *** 1 lock held by fsstress/6050: #0: ffff888113f26d18 (&vma->vm_lock->lock){++++}-{3:3}, at: lock_vma_under_rcu+0x165/0x250 stack backtrace: CPU: 0 PID: 6050 Comm: fsstress Not tainted 6.10.0-build2+ #956 Hardware name: ASUS All Series/H97-PLUS, BIOS 2306 10/09/2014 Call Trace: dump_stack_lvl+0x57/0x80 check_noncircular+0x119/0x160 ? queued_spin_lock_slowpath+0x4be/0x510 ? __pfx_check_noncircular+0x10/0x10 ? __pfx_queued_spin_lock_slowpath+0x10/0x10 ? mark_lock+0x47/0x160 ? init_chain_block+0x9c/0xc0 ? add_chain_block+0x84/0xf0 check_prev_add+0x195/0x430 __lock_acquire+0xaf0/0xd80 ? __pfx___lock_acquire+0x10/0x10 ? __lock_release.isra.0+0x13b/0x230 lock_acquire.part.0+0x103/0x280 ? filemap_fault+0x26e/0x8b0 ? __pfx_lock_acquire.part.0+0x10/0x10 ? rcu_is_watching+0x34/0x60 ? lock_acquire+0xd7/0x120 down_read+0x95/0x200 ? filemap_fault+0x26e/0x8b0 ? __pfx_down_read+0x10/0x10 ? __filemap_get_folio+0x25/0x1a0 filemap_fault+0x26e/0x8b0 ? __pfx_filemap_fault+0x10/0x10 ? find_held_lock+0x7c/0x90 ? __pfx___lock_release.isra.0+0x10/0x10 ? __pte_offset_map+0x99/0x110 __do_fault+0x57/0xd0 do_pte_missing+0x23b/0x320 __handle_mm_fault+0x2d4/0x320 ? __pfx___handle_mm_fault+0x10/0x10 handle_mm_fault+0x14f/0x260 do_user_addr_fault+0x2a2/0x500 exc_page_fault+0x71/0x90 asm_exc_page_fault+0x22/0x30 Signed-off-by: David Howells Link: https://lore.kernel.org/r/2136178.1721725194@warthog.procyon.org.uk cc: Alexander Viro cc: Christian Brauner cc: Jan Kara cc: Jeff Layton cc: Gao Xiang cc: Matthew Wilcox cc: netfs@lists.linux.dev cc: linux-erofs@lists.ozlabs.org cc: linux-fsdevel@vger.kernel.org [brauner: fix minor issues] Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

tmpfs,xattr: GFP_KERNEL_ACCOUNT for simple xattrs

2023-08-22T08:57:46+00:00

It is particularly important for the userns mount case (when a sensible nr_inodes maximum may not be enforced) that tmpfs user xattrs be subject to memory cgroup limiting. Leave temporary buffer allocations as is, but change the persistent simple xattr allocations from GFP_KERNEL to GFP_KERNEL_ACCOUNT. This limits kernfs's cgroupfs too, but that's good. (I had intended to send this change earlier, but had been confused by shmem_alloc_inode() using GFP_KERNEL, and thought a discussion would be needed to change that too: no, I was forgetting the SLAB_ACCOUNT on that kmem_cache, which implicitly adds __GFP_ACCOUNT to all its allocations.) Signed-off-by: Hugh Dickins Reviewed-by: Jan Kara Message-Id: Signed-off-by: Christian Brauner

tmpfs,xattr: enable limited user extended attributes

2023-08-10T10:06:04+00:00

Enable "user." extended attributes on tmpfs, limiting them by tracking the space they occupy, and deducting that space from the limited ispace (unless tmpfs mounted with nr_inodes=0 to leave that ispace unlimited). tmpfs inodes and simple xattrs are both unswappable, and have to be in lowmem on a 32-bit highmem kernel: so the ispace limit is appropriate for xattrs, without any need for a further mount option. Add simple_xattr_space() to give approximate but deterministic estimate of the space taken up by each xattr: with simple_xattrs_free() outputting the space freed if required (but kernfs and even some tmpfs usages do not require that, so don't waste time on strlen'ing if not needed). Security and trusted xattrs were already supported: for consistency and simplicity, account them from the same pool; though there's a small risk that a tmpfs with enough space before would now be considered too small. When extended attributes are used, "df -i" does show more IUsed and less IFree than can be explained by the inodes: document that (manpage later). xfstests tests/generic which were not run on tmpfs before but now pass: 020 037 062 070 077 097 103 117 337 377 454 486 523 533 611 618 728 with no new failures. Signed-off-by: Hugh Dickins Reviewed-by: Jan Kara Reviewed-by: Carlos Maiolino Message-Id: <2e63b26e-df46-5baa-c7d6-f9a8dd3282c5@google.com> Signed-off-by: Christian Brauner

xattr: simple_xattr_set() return old_xattr to be freed

2023-08-09T07:15:51+00:00

tmpfs wants to support limited user extended attributes, but kernfs (or cgroupfs, the only kernfs with KERNFS_ROOT_SUPPORT_USER_XATTR) already supports user extended attributes through simple xattrs: but limited by a policy (128KiB per inode) too liberal to be used on tmpfs. To allow a different limiting policy for tmpfs, without affecting the policy for kernfs, change simple_xattr_set() to return the replaced or removed xattr (if any), leaving the caller to update their accounting then free the xattr (by simple_xattr_free(), renamed from the static free_simple_xattr()). Signed-off-by: Hugh Dickins Reviewed-by: Jan Kara Reviewed-by: Christian Brauner Reviewed-by: Carlos Maiolino Message-Id: <158c6585-2aa7-d4aa-90ff-f7c3f8fe407c@google.com> Signed-off-by: Christian Brauner

fs: don't call posix_acl_listxattr in generic_listxattr

2023-05-17T13:25:20+00:00

Commit f2620f166e2a caused the kernel to start emitting POSIX ACL xattrs for NFSv4 inodes, which it doesn't support. The only other user of generic_listxattr is HFS (classic) and it doesn't support POSIX ACLs either. Fixes: f2620f166e2a xattr: simplify listxattr helpers Reported-by: Ondrej Valousek Signed-off-by: Jeff Layton Message-Id: <20230516124655.82283-1-jlayton@kernel.org> Signed-off-by: Christian Brauner