Searched +hist:80 +hist:b9bbef (Results 1 - 3 of 3) sorted by relevance
/linux-master/fs/sysfs/ | ||
H A D | mount.c | diff 80b9bbef Wed Dec 11 14:03:00 MST 2013 Tejun Heo <tj@kernel.org> kernfs: add kernfs_dir_ops Add support for mkdir(2), rmdir(2) and rename(2) syscalls. This is implemented through optional kernfs_dir_ops callback table which can be specified on kernfs_create_root(). An implemented callback is invoked when the matching syscall is invoked. As kernfs keep dcache syncs with internal representation and revalidates dentries on each access, the implementation of these methods is extremely simple. Each just discovers the relevant kernfs_node(s) and invokes the requested callback which is allowed to do any kernfs operations and the end result doesn't necessarily have to match the expected semantics of the syscall. This will be used to convert cgroup to use kernfs instead of its own filesystem implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> diff 80b9bbef Wed Dec 11 14:03:00 MST 2013 Tejun Heo <tj@kernel.org> kernfs: add kernfs_dir_ops Add support for mkdir(2), rmdir(2) and rename(2) syscalls. This is implemented through optional kernfs_dir_ops callback table which can be specified on kernfs_create_root(). An implemented callback is invoked when the matching syscall is invoked. As kernfs keep dcache syncs with internal representation and revalidates dentries on each access, the implementation of these methods is extremely simple. Each just discovers the relevant kernfs_node(s) and invokes the requested callback which is allowed to do any kernfs operations and the end result doesn't necessarily have to match the expected semantics of the syscall. This will be used to convert cgroup to use kernfs instead of its own filesystem implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
/linux-master/include/linux/ | ||
H A D | kernfs.h | diff 80b9bbef Wed Dec 11 14:03:00 MST 2013 Tejun Heo <tj@kernel.org> kernfs: add kernfs_dir_ops Add support for mkdir(2), rmdir(2) and rename(2) syscalls. This is implemented through optional kernfs_dir_ops callback table which can be specified on kernfs_create_root(). An implemented callback is invoked when the matching syscall is invoked. As kernfs keep dcache syncs with internal representation and revalidates dentries on each access, the implementation of these methods is extremely simple. Each just discovers the relevant kernfs_node(s) and invokes the requested callback which is allowed to do any kernfs operations and the end result doesn't necessarily have to match the expected semantics of the syscall. This will be used to convert cgroup to use kernfs instead of its own filesystem implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> diff 80b9bbef Wed Dec 11 14:03:00 MST 2013 Tejun Heo <tj@kernel.org> kernfs: add kernfs_dir_ops Add support for mkdir(2), rmdir(2) and rename(2) syscalls. This is implemented through optional kernfs_dir_ops callback table which can be specified on kernfs_create_root(). An implemented callback is invoked when the matching syscall is invoked. As kernfs keep dcache syncs with internal representation and revalidates dentries on each access, the implementation of these methods is extremely simple. Each just discovers the relevant kernfs_node(s) and invokes the requested callback which is allowed to do any kernfs operations and the end result doesn't necessarily have to match the expected semantics of the syscall. This will be used to convert cgroup to use kernfs instead of its own filesystem implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
/linux-master/fs/kernfs/ | ||
H A D | dir.c | diff 4abc9965 Tue Sep 13 06:17:23 MDT 2022 Christian A. Ehrhardt <lk@c--e.de> kernfs: fix use-after-free in __kernfs_remove 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, <r1=>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: <TASK> __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 </TASK> 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 <tj@kernel.org> Cc: stable <stable@kernel.org> # -rc3 Signed-off-by: Christian A. Ehrhardt <lk@c--e.de> Link: https://lore.kernel.org/r/20220913121723.691454-1-lk@c--e.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> diff 4abc9965 Tue Sep 13 06:17:23 MDT 2022 Christian A. Ehrhardt <lk@c--e.de> kernfs: fix use-after-free in __kernfs_remove 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, <r1=>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: <TASK> __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 </TASK> 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 <tj@kernel.org> Cc: stable <stable@kernel.org> # -rc3 Signed-off-by: Christian A. Ehrhardt <lk@c--e.de> Link: https://lore.kernel.org/r/20220913121723.691454-1-lk@c--e.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> diff 4abc9965 Tue Sep 13 06:17:23 MDT 2022 Christian A. Ehrhardt <lk@c--e.de> kernfs: fix use-after-free in __kernfs_remove 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, <r1=>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: <TASK> __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 </TASK> 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 <tj@kernel.org> Cc: stable <stable@kernel.org> # -rc3 Signed-off-by: Christian A. Ehrhardt <lk@c--e.de> Link: https://lore.kernel.org/r/20220913121723.691454-1-lk@c--e.de Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> diff 26e28d68 Tue Feb 05 21:55:42 MST 2019 Ayush Mittal <ayush.m@samsung.com> kernfs: Allocating memory for kernfs_iattrs with kmem_cache. Creating a new cache for kernfs_iattrs. Currently, memory is allocated with kzalloc() which always gives aligned memory. On ARM, this is 64 byte aligned. To avoid the wastage of memory in aligning the size requested, a new cache for kernfs_iattrs is created. Size of struct kernfs_iattrs is 80 Bytes. On ARM, it will come in kmalloc-128 slab. and it will come in kmalloc-192 slab if debug info is enabled. Extra bytes taken 48 bytes. Total number of objects created : 4096 Total saving = 48*4096 = 192 KB After creating new slab(When debug info is enabled) : sh-3.2# cat /proc/slabinfo ... kernfs_iattrs_cache 4069 4096 128 32 1 : tunables 0 0 0 : slabdata 128 128 0 ... All testing has been done on ARM target. Signed-off-by: Ayush Mittal <ayush.m@samsung.com> Signed-off-by: Vaneet Narang <v.narang@samsung.com> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> diff 95582b00 Tue May 08 20:36:02 MDT 2018 Deepa Dinamani <deepa.kernel@gmail.com> vfs: change inode times to use struct timespec64 struct timespec is not y2038 safe. Transition vfs to use y2038 safe struct timespec64 instead. The change was made with the help of the following cocinelle script. This catches about 80% of the changes. All the header file and logic changes are included in the first 5 rules. The rest are trivial substitutions. I avoid changing any of the function signatures or any other filesystem specific data structures to keep the patch simple for review. The script can be a little shorter by combining different cases. But, this version was sufficient for my usecase. virtual patch @ depends on patch @ identifier now; @@ - struct timespec + struct timespec64 current_time ( ... ) { - struct timespec now = current_kernel_time(); + struct timespec64 now = current_kernel_time64(); ... - return timespec_trunc( + return timespec64_trunc( ... ); } @ depends on patch @ identifier xtime; @@ struct \( iattr \| inode \| kstat \) { ... - struct timespec xtime; + struct timespec64 xtime; ... } @ depends on patch @ identifier t; @@ struct inode_operations { ... int (*update_time) (..., - struct timespec t, + struct timespec64 t, ...); ... } @ depends on patch @ identifier t; identifier fn_update_time =~ "update_time$"; @@ fn_update_time (..., - struct timespec *t, + struct timespec64 *t, ...) { ... } @ depends on patch @ identifier t; @@ lease_get_mtime( ... , - struct timespec *t + struct timespec64 *t ) { ... } @te depends on patch forall@ identifier ts; local idexpression struct inode *inode_node; identifier i_xtime =~ "^i_[acm]time$"; identifier ia_xtime =~ "^ia_[acm]time$"; identifier fn_update_time =~ "update_time$"; identifier fn; expression e, E3; local idexpression struct inode *node1; local idexpression struct inode *node2; local idexpression struct iattr *attr1; local idexpression struct iattr *attr2; local idexpression struct iattr attr; identifier i_xtime1 =~ "^i_[acm]time$"; identifier i_xtime2 =~ "^i_[acm]time$"; identifier ia_xtime1 =~ "^ia_[acm]time$"; identifier ia_xtime2 =~ "^ia_[acm]time$"; @@ ( ( - struct timespec ts; + struct timespec64 ts; | - struct timespec ts = current_time(inode_node); + struct timespec64 ts = current_time(inode_node); ) <+... when != ts ( - timespec_equal(&inode_node->i_xtime, &ts) + timespec64_equal(&inode_node->i_xtime, &ts) | - timespec_equal(&ts, &inode_node->i_xtime) + timespec64_equal(&ts, &inode_node->i_xtime) | - timespec_compare(&inode_node->i_xtime, &ts) + timespec64_compare(&inode_node->i_xtime, &ts) | - timespec_compare(&ts, &inode_node->i_xtime) + timespec64_compare(&ts, &inode_node->i_xtime) | ts = current_time(e) | fn_update_time(..., &ts,...) | inode_node->i_xtime = ts | node1->i_xtime = ts | ts = inode_node->i_xtime | <+... attr1->ia_xtime ...+> = ts | ts = attr1->ia_xtime | ts.tv_sec | ts.tv_nsec | btrfs_set_stack_timespec_sec(..., ts.tv_sec) | btrfs_set_stack_timespec_nsec(..., ts.tv_nsec) | - ts = timespec64_to_timespec( + ts = ... -) | - ts = ktime_to_timespec( + ts = ktime_to_timespec64( ...) | - ts = E3 + ts = timespec_to_timespec64(E3) | - ktime_get_real_ts(&ts) + ktime_get_real_ts64(&ts) | fn(..., - ts + timespec64_to_timespec(ts) ,...) ) ...+> ( <... when != ts - return ts; + return timespec64_to_timespec(ts); ...> ) | - timespec_equal(&node1->i_xtime1, &node2->i_xtime2) + timespec64_equal(&node1->i_xtime2, &node2->i_xtime2) | - timespec_equal(&node1->i_xtime1, &attr2->ia_xtime2) + timespec64_equal(&node1->i_xtime2, &attr2->ia_xtime2) | - timespec_compare(&node1->i_xtime1, &node2->i_xtime2) + timespec64_compare(&node1->i_xtime1, &node2->i_xtime2) | node1->i_xtime1 = - timespec_trunc(attr1->ia_xtime1, + timespec64_trunc(attr1->ia_xtime1, ...) | - attr1->ia_xtime1 = timespec_trunc(attr2->ia_xtime2, + attr1->ia_xtime1 = timespec64_trunc(attr2->ia_xtime2, ...) | - ktime_get_real_ts(&attr1->ia_xtime1) + ktime_get_real_ts64(&attr1->ia_xtime1) | - ktime_get_real_ts(&attr.ia_xtime1) + ktime_get_real_ts64(&attr.ia_xtime1) ) @ depends on patch @ struct inode *node; struct iattr *attr; identifier fn; identifier i_xtime =~ "^i_[acm]time$"; identifier ia_xtime =~ "^ia_[acm]time$"; expression e; @@ ( - fn(node->i_xtime); + fn(timespec64_to_timespec(node->i_xtime)); | fn(..., - node->i_xtime); + timespec64_to_timespec(node->i_xtime)); | - e = fn(attr->ia_xtime); + e = fn(timespec64_to_timespec(attr->ia_xtime)); ) @ depends on patch forall @ struct inode *node; struct iattr *attr; identifier i_xtime =~ "^i_[acm]time$"; identifier ia_xtime =~ "^ia_[acm]time$"; identifier fn; @@ { + struct timespec ts; <+... ( + ts = timespec64_to_timespec(node->i_xtime); fn (..., - &node->i_xtime, + &ts, ...); | + ts = timespec64_to_timespec(attr->ia_xtime); fn (..., - &attr->ia_xtime, + &ts, ...); ) ...+> } @ depends on patch forall @ struct inode *node; struct iattr *attr; struct kstat *stat; identifier ia_xtime =~ "^ia_[acm]time$"; identifier i_xtime =~ "^i_[acm]time$"; identifier xtime =~ "^[acm]time$"; identifier fn, ret; @@ { + struct timespec ts; <+... ( + ts = timespec64_to_timespec(node->i_xtime); ret = fn (..., - &node->i_xtime, + &ts, ...); | + ts = timespec64_to_timespec(node->i_xtime); ret = fn (..., - &node->i_xtime); + &ts); | + ts = timespec64_to_timespec(attr->ia_xtime); ret = fn (..., - &attr->ia_xtime, + &ts, ...); | + ts = timespec64_to_timespec(attr->ia_xtime); ret = fn (..., - &attr->ia_xtime); + &ts); | + ts = timespec64_to_timespec(stat->xtime); ret = fn (..., - &stat->xtime); + &ts); ) ...+> } @ depends on patch @ struct inode *node; struct inode *node2; identifier i_xtime1 =~ "^i_[acm]time$"; identifier i_xtime2 =~ "^i_[acm]time$"; identifier i_xtime3 =~ "^i_[acm]time$"; struct iattr *attrp; struct iattr *attrp2; struct iattr attr ; identifier ia_xtime1 =~ "^ia_[acm]time$"; identifier ia_xtime2 =~ "^ia_[acm]time$"; struct kstat *stat; struct kstat stat1; struct timespec64 ts; identifier xtime =~ "^[acmb]time$"; expression e; @@ ( ( node->i_xtime2 \| attrp->ia_xtime2 \| attr.ia_xtime2 \) = node->i_xtime1 ; | node->i_xtime2 = \( node2->i_xtime1 \| timespec64_trunc(...) \); | node->i_xtime2 = node->i_xtime1 = node->i_xtime3 = \(ts \| current_time(...) \); | node->i_xtime1 = node->i_xtime3 = \(ts \| current_time(...) \); | stat->xtime = node2->i_xtime1; | stat1.xtime = node2->i_xtime1; | ( node->i_xtime2 \| attrp->ia_xtime2 \) = attrp->ia_xtime1 ; | ( attrp->ia_xtime1 \| attr.ia_xtime1 \) = attrp2->ia_xtime2; | - e = node->i_xtime1; + e = timespec64_to_timespec( node->i_xtime1 ); | - e = attrp->ia_xtime1; + e = timespec64_to_timespec( attrp->ia_xtime1 ); | node->i_xtime1 = current_time(...); | node->i_xtime2 = node->i_xtime1 = node->i_xtime3 = - e; + timespec_to_timespec64(e); | node->i_xtime1 = node->i_xtime3 = - e; + timespec_to_timespec64(e); | - node->i_xtime1 = e; + node->i_xtime1 = timespec_to_timespec64(e); ) Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com> Cc: <anton@tuxera.com> Cc: <balbi@kernel.org> Cc: <bfields@fieldses.org> Cc: <darrick.wong@oracle.com> Cc: <dhowells@redhat.com> Cc: <dsterba@suse.com> Cc: <dwmw2@infradead.org> Cc: <hch@lst.de> Cc: <hirofumi@mail.parknet.co.jp> Cc: <hubcap@omnibond.com> Cc: <jack@suse.com> Cc: <jaegeuk@kernel.org> Cc: <jaharkes@cs.cmu.edu> Cc: <jslaby@suse.com> Cc: <keescook@chromium.org> Cc: <mark@fasheh.com> Cc: <miklos@szeredi.hu> Cc: <nico@linaro.org> Cc: <reiserfs-devel@vger.kernel.org> Cc: <richard@nod.at> Cc: <sage@redhat.com> Cc: <sfrench@samba.org> Cc: <swhiteho@redhat.com> Cc: <tj@kernel.org> Cc: <trond.myklebust@primarydata.com> Cc: <tytso@mit.edu> Cc: <viro@zeniv.linux.org.uk> diff 80b9bbef Wed Dec 11 14:03:00 MST 2013 Tejun Heo <tj@kernel.org> kernfs: add kernfs_dir_ops Add support for mkdir(2), rmdir(2) and rename(2) syscalls. This is implemented through optional kernfs_dir_ops callback table which can be specified on kernfs_create_root(). An implemented callback is invoked when the matching syscall is invoked. As kernfs keep dcache syncs with internal representation and revalidates dentries on each access, the implementation of these methods is extremely simple. Each just discovers the relevant kernfs_node(s) and invokes the requested callback which is allowed to do any kernfs operations and the end result doesn't necessarily have to match the expected semantics of the syscall. This will be used to convert cgroup to use kernfs instead of its own filesystem implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> diff 80b9bbef Wed Dec 11 14:03:00 MST 2013 Tejun Heo <tj@kernel.org> kernfs: add kernfs_dir_ops Add support for mkdir(2), rmdir(2) and rename(2) syscalls. This is implemented through optional kernfs_dir_ops callback table which can be specified on kernfs_create_root(). An implemented callback is invoked when the matching syscall is invoked. As kernfs keep dcache syncs with internal representation and revalidates dentries on each access, the implementation of these methods is extremely simple. Each just discovers the relevant kernfs_node(s) and invokes the requested callback which is allowed to do any kernfs operations and the end result doesn't necessarily have to match the expected semantics of the syscall. This will be used to convert cgroup to use kernfs instead of its own filesystem implementation. Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
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