kernel.git/fs/kernfs, branch linux-5.4.y

fs/kernfs/dir: obey S_ISGID

2024-02-23T07:25:03Z

[ Upstream commit 5133bee62f0ea5d4c316d503cc0040cac5637601 ] Handling of S_ISGID is usually done by inode_init_owner() in all other filesystems, but kernfs doesn't use that function. In kernfs, struct kernfs_node is the primary data structure, and struct inode is only created from it on demand. Therefore, inode_init_owner() can't be used and we need to imitate its behavior. S_ISGID support is useful for the cgroup filesystem; it allows subtrees managed by an unprivileged process to retain a certain owner gid, which then enables sharing access to the subtree with another unprivileged process. -- v1 -> v2: minor coding style fix (comment) Signed-off-by: Max Kellermann Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20231208093310.297233-2-max.kellermann@ionos.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

new helper: lookup_positive_unlocked()

2023-09-23T08:59:40Z

[ Upstream commit 6c2d4798a8d16cf4f3a28c3cd4af4f1dcbbb4d04 ] Most of the callers of lookup_one_len_unlocked() treat negatives are ERR_PTR(-ENOENT). Provide a helper that would do just that. Note that a pinned positive dentry remains positive - it's ->d_inode is stable, etc.; a pinned _negative_ dentry can become positive at any point as long as you are not holding its parent at least shared. So using lookup_one_len_unlocked() needs to be careful; lookup_positive_unlocked() is safer and that's what the callers end up open-coding anyway. Signed-off-by: Al Viro Stable-dep-of: 0d5a4f8f775f ("fs: Fix error checking for d_hash_and_lookup()") Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman

kernfs: fix use-after-free in __kernfs_remove

2022-11-03T14:56:54Z

commit 4abc99652812a2ddf932f137515d5c5a04723538 upstream. Syzkaller managed to trigger concurrent calls to kernfs_remove_by_name_ns() for the same file resulting in a KASAN detected use-after-free. The race occurs when the root node is freed during kernfs_drain(). To prevent this acquire an additional reference for the root of the tree that is removed before calling __kernfs_remove(). Found by syzkaller with the following reproducer (slab_nomerge is required): syz_mount_image$ext4(0x0, &(0x7f0000000100)='./file0\x00', 0x100000, 0x0, 0x0, 0x0, 0x0) r0 = openat(0xffffffffffffff9c, &(0x7f0000000080)='/proc/self/exe\x00', 0x0, 0x0) close(r0) pipe2(&(0x7f0000000140)={0xffffffffffffffff, 0xffffffffffffffff}, 0x800) mount$9p_fd(0x0, &(0x7f0000000040)='./file0\x00', &(0x7f00000000c0), 0x408, &(0x7f0000000280)={'trans=fd,', {'rfdno', 0x3d, r0}, 0x2c, {'wfdno', 0x3d, r1}, 0x2c, {[{@cache_loose}, {@mmap}, {@loose}, {@loose}, {@mmap}], [{@mask={'mask', 0x3d, '^MAY_EXEC'}}, {@fsmagic={'fsmagic', 0x3d, 0x10001}}, {@dont_hash}]}}) Sample report: ================================================================== BUG: KASAN: use-after-free in kernfs_type include/linux/kernfs.h:335 [inline] BUG: KASAN: use-after-free in kernfs_leftmost_descendant fs/kernfs/dir.c:1261 [inline] BUG: KASAN: use-after-free in __kernfs_remove.part.0+0x843/0x960 fs/kernfs/dir.c:1369 Read of size 2 at addr ffff8880088807f0 by task syz-executor.2/857 CPU: 0 PID: 857 Comm: syz-executor.2 Not tainted 6.0.0-rc3-00363-g7726d4c3e60b #5 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014 Call Trace: __dump_stack lib/dump_stack.c:88 [inline] dump_stack_lvl+0x6e/0x91 lib/dump_stack.c:106 print_address_description mm/kasan/report.c:317 [inline] print_report.cold+0x5e/0x5e5 mm/kasan/report.c:433 kasan_report+0xa3/0x130 mm/kasan/report.c:495 kernfs_type include/linux/kernfs.h:335 [inline] kernfs_leftmost_descendant fs/kernfs/dir.c:1261 [inline] __kernfs_remove.part.0+0x843/0x960 fs/kernfs/dir.c:1369 __kernfs_remove fs/kernfs/dir.c:1356 [inline] kernfs_remove_by_name_ns+0x108/0x190 fs/kernfs/dir.c:1589 sysfs_slab_add+0x133/0x1e0 mm/slub.c:5943 __kmem_cache_create+0x3e0/0x550 mm/slub.c:4899 create_cache mm/slab_common.c:229 [inline] kmem_cache_create_usercopy+0x167/0x2a0 mm/slab_common.c:335 p9_client_create+0xd4d/0x1190 net/9p/client.c:993 v9fs_session_init+0x1e6/0x13c0 fs/9p/v9fs.c:408 v9fs_mount+0xb9/0xbd0 fs/9p/vfs_super.c:126 legacy_get_tree+0xf1/0x200 fs/fs_context.c:610 vfs_get_tree+0x85/0x2e0 fs/super.c:1530 do_new_mount fs/namespace.c:3040 [inline] path_mount+0x675/0x1d00 fs/namespace.c:3370 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x282/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f725f983aed Code: 02 b8 ff ff ff ff c3 66 0f 1f 44 00 00 f3 0f 1e fa 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f725f0f7028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5 RAX: ffffffffffffffda RBX: 00007f725faa3f80 RCX: 00007f725f983aed RDX: 00000000200000c0 RSI: 0000000020000040 RDI: 0000000000000000 RBP: 00007f725f9f419c R08: 0000000020000280 R09: 0000000000000000 R10: 0000000000000408 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000006 R14: 00007f725faa3f80 R15: 00007f725f0d7000 Allocated by task 855: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track mm/kasan/common.c:45 [inline] set_alloc_info mm/kasan/common.c:437 [inline] __kasan_slab_alloc+0x66/0x80 mm/kasan/common.c:470 kasan_slab_alloc include/linux/kasan.h:224 [inline] slab_post_alloc_hook mm/slab.h:727 [inline] slab_alloc_node mm/slub.c:3243 [inline] slab_alloc mm/slub.c:3251 [inline] __kmem_cache_alloc_lru mm/slub.c:3258 [inline] kmem_cache_alloc+0xbf/0x200 mm/slub.c:3268 kmem_cache_zalloc include/linux/slab.h:723 [inline] __kernfs_new_node+0xd4/0x680 fs/kernfs/dir.c:593 kernfs_new_node fs/kernfs/dir.c:655 [inline] kernfs_create_dir_ns+0x9c/0x220 fs/kernfs/dir.c:1010 sysfs_create_dir_ns+0x127/0x290 fs/sysfs/dir.c:59 create_dir lib/kobject.c:63 [inline] kobject_add_internal+0x24a/0x8d0 lib/kobject.c:223 kobject_add_varg lib/kobject.c:358 [inline] kobject_init_and_add+0x101/0x160 lib/kobject.c:441 sysfs_slab_add+0x156/0x1e0 mm/slub.c:5954 __kmem_cache_create+0x3e0/0x550 mm/slub.c:4899 create_cache mm/slab_common.c:229 [inline] kmem_cache_create_usercopy+0x167/0x2a0 mm/slab_common.c:335 p9_client_create+0xd4d/0x1190 net/9p/client.c:993 v9fs_session_init+0x1e6/0x13c0 fs/9p/v9fs.c:408 v9fs_mount+0xb9/0xbd0 fs/9p/vfs_super.c:126 legacy_get_tree+0xf1/0x200 fs/fs_context.c:610 vfs_get_tree+0x85/0x2e0 fs/super.c:1530 do_new_mount fs/namespace.c:3040 [inline] path_mount+0x675/0x1d00 fs/namespace.c:3370 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x282/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd Freed by task 857: kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38 kasan_set_track+0x21/0x30 mm/kasan/common.c:45 kasan_set_free_info+0x20/0x40 mm/kasan/generic.c:370 ____kasan_slab_free mm/kasan/common.c:367 [inline] ____kasan_slab_free mm/kasan/common.c:329 [inline] __kasan_slab_free+0x108/0x190 mm/kasan/common.c:375 kasan_slab_free include/linux/kasan.h:200 [inline] slab_free_hook mm/slub.c:1754 [inline] slab_free_freelist_hook mm/slub.c:1780 [inline] slab_free mm/slub.c:3534 [inline] kmem_cache_free+0x9c/0x340 mm/slub.c:3551 kernfs_put.part.0+0x2b2/0x520 fs/kernfs/dir.c:547 kernfs_put+0x42/0x50 fs/kernfs/dir.c:521 __kernfs_remove.part.0+0x72d/0x960 fs/kernfs/dir.c:1407 __kernfs_remove fs/kernfs/dir.c:1356 [inline] kernfs_remove_by_name_ns+0x108/0x190 fs/kernfs/dir.c:1589 sysfs_slab_add+0x133/0x1e0 mm/slub.c:5943 __kmem_cache_create+0x3e0/0x550 mm/slub.c:4899 create_cache mm/slab_common.c:229 [inline] kmem_cache_create_usercopy+0x167/0x2a0 mm/slab_common.c:335 p9_client_create+0xd4d/0x1190 net/9p/client.c:993 v9fs_session_init+0x1e6/0x13c0 fs/9p/v9fs.c:408 v9fs_mount+0xb9/0xbd0 fs/9p/vfs_super.c:126 legacy_get_tree+0xf1/0x200 fs/fs_context.c:610 vfs_get_tree+0x85/0x2e0 fs/super.c:1530 do_new_mount fs/namespace.c:3040 [inline] path_mount+0x675/0x1d00 fs/namespace.c:3370 do_mount fs/namespace.c:3383 [inline] __do_sys_mount fs/namespace.c:3591 [inline] __se_sys_mount fs/namespace.c:3568 [inline] __x64_sys_mount+0x282/0x300 fs/namespace.c:3568 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0x90 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd The buggy address belongs to the object at ffff888008880780 which belongs to the cache kernfs_node_cache of size 128 The buggy address is located 112 bytes inside of 128-byte region [ffff888008880780, ffff888008880800) The buggy address belongs to the physical page: page:00000000732833f8 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x8880 flags: 0x100000000000200(slab|node=0|zone=1) raw: 0100000000000200 0000000000000000 dead000000000122 ffff888001147280 raw: 0000000000000000 0000000000150015 00000001ffffffff 0000000000000000 page dumped because: kasan: bad access detected Memory state around the buggy address: ffff888008880680: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ffff888008880700: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc >ffff888008880780: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb ^ ffff888008880800: fc fc fc fc fc fc fc fc fa fb fb fb fb fb fb fb ffff888008880880: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc ================================================================== Acked-by: Tejun Heo Cc: stable # -rc3 Signed-off-by: Christian A. Ehrhardt Link: https://lore.kernel.org/r/20220913121723.691454-1-lk@c--e.de Signed-off-by: Greg Kroah-Hartman Signed-off-by: Greg Kroah-Hartman

kernfs: Separate kernfs_pr_cont_buf and rename_lock.

2022-06-14T16:12:00Z

[ Upstream commit 1a702dc88e150487c9c173a249b3d236498b9183 ] Previously the protection of kernfs_pr_cont_buf was piggy backed by rename_lock, which means that pr_cont() needs to be protected under rename_lock. This can cause potential circular lock dependencies. If there is an OOM, we have the following call hierarchy: -> cpuset_print_current_mems_allowed() -> pr_cont_cgroup_name() -> pr_cont_kernfs_name() pr_cont_kernfs_name() will grab rename_lock and call printk. So we have the following lock dependencies: kernfs_rename_lock -> console_sem Sometimes, printk does a wakeup before releasing console_sem, which has the dependence chain: console_sem -> p->pi_lock -> rq->lock Now, imagine one wants to read cgroup_name under rq->lock, for example, printing cgroup_name in a tracepoint in the scheduler code. They will be holding rq->lock and take rename_lock: rq->lock -> kernfs_rename_lock Now they will deadlock. A prevention to this circular lock dependency is to separate the protection of pr_cont_buf from rename_lock. In principle, rename_lock is to protect the integrity of cgroup name when copying to buf. Once pr_cont_buf has got its content, rename_lock can be dropped. So it's safe to drop rename_lock after kernfs_name_locked (and kernfs_path_from_node_locked) and rely on a dedicated pr_cont_lock to protect pr_cont_buf. Acked-by: Tejun Heo Signed-off-by: Hao Luo Link: https://lore.kernel.org/r/20220516190951.3144144-1-haoluo@google.com Signed-off-by: Greg Kroah-Hartman Signed-off-by: Sasha Levin

kernfs: do not call fsnotify() with name without a parent

2020-08-19T06:16:12Z

[ Upstream commit 9991bb84b27a2594187898f261866cfc50255454 ] When creating an FS_MODIFY event on inode itself (not on parent) the file_name argument should be NULL. The change to send a non NULL name to inode itself was done on purpuse as part of another commit, as Tejun writes: "...While at it, supply the target file name to fsnotify() from kernfs_node->name.". But this is wrong practice and inconsistent with inotify behavior when watching a single file. When a child is being watched (as opposed to the parent directory) the inotify event should contain the watch descriptor, but not the file name. Fixes: df6a58c5c5aa ("kernfs: don't depend on d_find_any_alias()...") Link: https://lore.kernel.org/r/20200708111156.24659-5-amir73il@gmail.com Acked-by: Tejun Heo Acked-by: Greg Kroah-Hartman Signed-off-by: Amir Goldstein Signed-off-by: Jan Kara Signed-off-by: Sasha Levin

kernfs: fix ino wrap-around detection

2019-12-13T07:42:53Z

commit e23f568aa63f64cd6b355094224cc9356c0f696b upstream. When the 32bit ino wraps around, kernfs increments the generation number to distinguish reused ino instances. The wrap-around detection tests whether the allocated ino is lower than what the cursor but the cursor is pointing to the next ino to allocate so the condition never triggers. Fix it by remembering the last ino and comparing against that. Signed-off-by: Tejun Heo Reviewed-by: Greg Kroah-Hartman Fixes: 4a3ef68acacf ("kernfs: implement i_generation") Cc: Namhyung Kim Cc: stable@vger.kernel.org # v4.14+ Signed-off-by: Greg Kroah-Hartman

Merge tag 'y2038-vfs' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground

2019-09-19T16:42:37Z

Pull y2038 vfs updates from Arnd Bergmann: "Add inode timestamp clamping. This series from Deepa Dinamani adds a per-superblock minimum/maximum timestamp limit for a file system, and clamps timestamps as they are written, to avoid random behavior from integer overflow as well as having different time stamps on disk vs in memory. At mount time, a warning is now printed for any file system that can represent current timestamps but not future timestamps more than 30 years into the future, similar to the arbitrary 30 year limit that was added to settimeofday(). This was picked as a compromise to warn users to migrate to other file systems (e.g. ext4 instead of ext3) when they need the file system to survive beyond 2038 (or similar limits in other file systems), but not get in the way of normal usage" * tag 'y2038-vfs' of git://git.kernel.org/pub/scm/linux/kernel/git/arnd/playground: ext4: Reduce ext4 timestamp warnings isofs: Initialize filesystem timestamp ranges pstore: fs superblock limits fs: omfs: Initialize filesystem timestamp ranges fs: hpfs: Initialize filesystem timestamp ranges fs: ceph: Initialize filesystem timestamp ranges fs: sysv: Initialize filesystem timestamp ranges fs: affs: Initialize filesystem timestamp ranges fs: fat: Initialize filesystem timestamp ranges fs: cifs: Initialize filesystem timestamp ranges fs: nfs: Initialize filesystem timestamp ranges ext4: Initialize timestamps limits 9p: Fill min and max timestamps in sb fs: Fill in max and min timestamps in superblock utimes: Clamp the timestamps before update mount: Add mount warning for impending timestamp expiry timestamp_truncate: Replace users of timespec64_trunc vfs: Add timestamp_truncate() api vfs: Add file timestamp range support

timestamp_truncate: Replace users of timespec64_trunc

2019-08-30T14:27:17Z

Update the inode timestamp updates to use timestamp_truncate() instead of timespec64_trunc(). The change was mostly generated by the following coccinelle script. virtual context virtual patch @r1 depends on patch forall@ struct inode *inode; identifier i_xtime =~ "^i_[acm]time$"; expression e; @@ inode->i_xtime = - timespec64_trunc( + timestamp_truncate( ..., - e); + inode); Signed-off-by: Deepa Dinamani Acked-by: Greg Kroah-Hartman Acked-by: Jeff Layton Cc: adrian.hunter@intel.com Cc: dedekind1@gmail.com Cc: gregkh@linuxfoundation.org Cc: hch@lst.de Cc: jaegeuk@kernel.org Cc: jlbec@evilplan.org Cc: richard@nod.at Cc: tj@kernel.org Cc: yuchao0@huawei.com Cc: linux-f2fs-devel@lists.sourceforge.net Cc: linux-ntfs-dev@lists.sourceforge.net Cc: linux-mtd@lists.infradead.org

fs: kernfs: Fix possible null-pointer dereferences in kernfs_path_from_node_locked()

2019-07-25T13:32:51Z

In kernfs_path_from_node_locked(), there is an if statement on line 147 to check whether buf is NULL: if (buf) When buf is NULL, it is used on line 151: len += strlcpy(buf + len, parent_str, ...) and line 158: len += strlcpy(buf + len, "/", ...) and line 160: len += strlcpy(buf + len, kn->name, ...) Thus, possible null-pointer dereferences may occur. To fix these possible bugs, buf is checked before being used. If it is NULL, -EINVAL is returned. These bugs are found by a static analysis tool STCheck written by us. Signed-off-by: Jia-Ju Bai Link: https://lore.kernel.org/r/20190724022242.27505-1-baijiaju1990@gmail.com Signed-off-by: Greg Kroah-Hartman

kernfs: fix potential null pointer dereference

2019-07-25T13:30:48Z

Get root safely after kn is ensureed to be not null. Signed-off-by: Peng Wang Acked-by: Tejun Heo Link: https://lore.kernel.org/r/20190708151611.13242-1-rocking@whu.edu.cn Signed-off-by: Greg Kroah-Hartman