Commit Graph

142 Commits

Author SHA1 Message Date
Christian A. Ehrhardt
4abc996528 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>
2022-09-24 13:52:27 +02:00
Tejun Heo
783bd07d09 kernfs: Implement kernfs_show()
Currently, kernfs nodes can be created hidden and activated later by calling
kernfs_activate() to allow creation of multiple nodes to succeed or fail as
a unit. This is an one-way one-time-only transition. This patch introduces
kernfs_show() which can toggle visibility dynamically.

As the currently proposed use - toggling the cgroup pressure files - only
requires operating on leaf nodes, for the sake of simplicity, restrict it as
such for now.

Hiding uses the same mechanism as deactivation and likewise guarantees that
there are no in-flight operations on completion. KERNFS_ACTIVATED and
KERNFS_HIDDEN are used to manage the interactions between activations and
show/hide operations. A node is visible iff both activated & !hidden.

Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-9-tj@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-01 18:08:44 +02:00
Tejun Heo
f8eb145eb9 kernfs: Factor out kernfs_activate_one()
Factor out kernfs_activate_one() from kernfs_activate() and reorder
operations so that KERNFS_ACTIVATED now simply indicates whether activation
was attempted on the node ignoring whether activation took place. As the
flag doesn't have a reader, the refactoring and reordering shouldn't cause
any behavior difference.

Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-8-tj@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-01 18:08:44 +02:00
Tejun Heo
c25491747b kernfs: Add KERNFS_REMOVING flags
KERNFS_ACTIVATED tracks whether a given node has ever been activated. As a
node was only deactivated on removal, this was used for

 1. Drain optimization (removed by the previous patch).
 2. To hide !activated nodes
 3. To avoid double activations
 4. Reject adding children to a node being removed
 5. Skip activaing a node which is being removed.

We want to decouple deactivation from removal so that nodes can be
deactivated and hidden dynamically, which makes KERNFS_ACTIVATED useless for
all of the above purposes.

#1 is already gone. #2 and #3 can instead test whether the node is currently
active. A new flag KERNFS_REMOVING is added to explicitly mark nodes which
are being removed for #4 and #5.

While this leaves KERNFS_ACTIVATED with no users, leave it be as it will be
used in a following patch.

Cc: Chengming Zhou <zhouchengming@bytedance.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-7-tj@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-01 18:08:44 +02:00
Tejun Heo
2d7f9f8c18 kernfs: Improve kernfs_drain() and always call on removal
__kernfs_remove() was skipping draining based on KERNFS_ACTIVATED - whether
the node has ever been activated since creation. Instead, update it to
always call kernfs_drain() which now drains or skips based on the precise
drain conditions. This ensures that the nodes will be deactivated and
drained regardless of their states.

This doesn't make meaningful difference now but will enable deactivating and
draining nodes dynamically by making removals safe when racing those
operations.

While at it, drop / update comments.

v2: Fix the inverted test on kernfs_should_drain_open_files() noted by
    Chengming. This was fixed by the next unrelated patch in the previous
    posting.

Cc: Chengming Zhou <zhouchengming@bytedance.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-6-tj@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-01 18:08:44 +02:00
Tejun Heo
bdb2fd7fc5 kernfs: Skip kernfs_drain_open_files() more aggressively
Track the number of mmapped files and files that need to be released and
skip kernfs_drain_open_file() if both are zero, which are the precise
conditions which require draining open_files. The early exit test is
factored into kernfs_should_drain_open_files() which is now tested by
kernfs_drain_open_files()'s caller - kernfs_drain().

This isn't a meaningful optimization on its own but will enable future
stand-alone kernfs_deactivate() implementation.

v2: Chengming noticed that on->nr_to_release was leaking after ->open()
    failure. Fix it by telling kernfs_unlink_open_file() that it's called
    from the ->open() fail path and should dec the counter. Use kzalloc() to
    allocate kernfs_open_node so that the tracking fields are correctly
    initialized.

Cc: Chengming Zhou <zhouchengming@bytedance.com>
Tested-by: Chengming Zhou <zhouchengming@bytedance.com>
Reviewed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220828050440.734579-5-tj@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-09-01 18:08:44 +02:00
Yushan Zhou
72b5d5aef2 kernfs: fix potential NULL dereference in __kernfs_remove
When lockdep is enabled, lockdep_assert_held_write would
cause potential NULL pointer dereference.

Fix the following smatch warnings:

fs/kernfs/dir.c:1353 __kernfs_remove() warn: variable dereferenced before check 'kn' (see line 1346)

Fixes: 393c371408 ("kernfs: switch global kernfs_rwsem lock to per-fs lock")
Signed-off-by: Yushan Zhou <katrinzhou@tencent.com>
Link: https://lore.kernel.org/r/20220630082512.3482581-1-zys.zljxml@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-07-01 10:36:36 +02:00
Hao Luo
1a702dc88e kernfs: Separate kernfs_pr_cont_buf and rename_lock.
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 <tj@kernel.org>
Signed-off-by: Hao Luo <haoluo@google.com>
Link: https://lore.kernel.org/r/20220516190951.3144144-1-haoluo@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-05-19 19:37:06 +02:00
Minchan Kim
ad8d869343 kernfs: fix NULL dereferencing in kernfs_remove
kernfs_remove supported NULL kernfs_node param to bail out but revent
per-fs lock change introduced regression that dereferencing the
param without NULL check so kernel goes crash.

This patch checks the NULL kernfs_node in kernfs_remove and if so,
just return.

Quote from bug report by Jirka

```
The bug is triggered by running NAS Parallel benchmark suite on
SuperMicro servers with 2x Xeon(R) Gold 6126 CPU. Here is the error
log:

[  247.035564] BUG: kernel NULL pointer dereference, address: 0000000000000008
[  247.036009] #PF: supervisor read access in kernel mode
[  247.036009] #PF: error_code(0x0000) - not-present page
[  247.036009] PGD 0 P4D 0
[  247.036009] Oops: 0000 [#1] PREEMPT SMP PTI
[  247.058060] CPU: 1 PID: 6546 Comm: umount Not tainted
5.16.0393c3714081a53795bbff0e985d24146def6f57f+ #16
[  247.058060] Hardware name: Supermicro Super Server/X11DDW-L, BIOS
2.0b 03/07/2018
[  247.058060] RIP: 0010:kernfs_remove+0x8/0x50
[  247.058060] Code: 4c 89 e0 5b 5d 41 5c 41 5d 41 5e c3 49 c7 c4 f4
ff ff ff eb b2 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 0f 1f 44 00 00
41 54 55 <48> 8b 47 08 48 89 fd 48 85 c0 48 0f 44 c7 4c 8b 60 50 49 83
c4 60
[  247.058060] RSP: 0018:ffffbbfa48a27e48 EFLAGS: 00010246
[  247.058060] RAX: 0000000000000001 RBX: ffffffff89e31f98 RCX: 0000000080200018
[  247.058060] RDX: 0000000080200019 RSI: fffff6760786c900 RDI: 0000000000000000
[  247.058060] RBP: ffffffff89e31f98 R08: ffff926b61b24d00 R09: 0000000080200018
[  247.122048] R10: ffff926b61b24d00 R11: ffff926a8040c000 R12: ffff927bd09a2000
[  247.122048] R13: ffffffff89e31fa0 R14: dead000000000122 R15: dead000000000100
[  247.122048] FS:  00007f01be0a8c40(0000) GS:ffff926fa8e40000(0000)
knlGS:0000000000000000
[  247.122048] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  247.122048] CR2: 0000000000000008 CR3: 00000001145c6003 CR4: 00000000007706e0
[  247.122048] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  247.122048] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  247.122048] PKRU: 55555554
[  247.122048] Call Trace:
[  247.122048]  <TASK>
[  247.122048]  rdt_kill_sb+0x29d/0x350
[  247.122048]  deactivate_locked_super+0x36/0xa0
[  247.122048]  cleanup_mnt+0x131/0x190
[  247.122048]  task_work_run+0x5c/0x90
[  247.122048]  exit_to_user_mode_prepare+0x229/0x230
[  247.122048]  syscall_exit_to_user_mode+0x18/0x40
[  247.122048]  do_syscall_64+0x48/0x90
[  247.122048]  entry_SYSCALL_64_after_hwframe+0x44/0xae
[  247.122048] RIP: 0033:0x7f01be2d735b
```

Link: https://bugzilla.kernel.org/show_bug.cgi?id=215696
Link: https://lore.kernel.org/lkml/CAE4VaGDZr_4wzRn2___eDYRtmdPaGGJdzu_LCSkJYuY9BEO3cw@mail.gmail.com/
Fixes: 393c371408 (kernfs: switch global kernfs_rwsem lock to per-fs lock)
Cc: stable@vger.kernel.org
Reported-by: Jirka Hladky <jhladky@redhat.com>
Tested-by: Jirka Hladky <jhladky@redhat.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Link: https://lore.kernel.org/r/20220427172152.3505364-1-minchan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-04-27 19:32:07 +02:00
Greg Kroah-Hartman
f2eb478f2f kernfs: move struct kernfs_root out of the public view.
There is no need to have struct kernfs_root be part of kernfs.h for
the whole kernel to see and poke around it.  Move it internal to kernfs
code and provide a helper function, kernfs_root_to_node(), to handle the
one field that kernfs users were directly accessing from the structure.

Cc: Imran Khan <imran.f.khan@oracle.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20220222070713.3517679-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-02-23 15:46:34 +01:00
Minchan Kim
555a0ce455 kernfs: prevent early freeing of root node
Marek reported the warning below.

  =========================
  WARNING: held lock freed!
  5.16.0-rc2+ #10984 Not tainted
  -------------------------
  kworker/1:0/18 is freeing memory ffff00004034e200-ffff00004034e3ff,
with a lock still held there!
  ffff00004034e348 (&root->kernfs_rwsem){++++}-{3:3}, at:
__kernfs_remove+0x310/0x37c
  3 locks held by kworker/1:0/18:
   #0: ffff000040107938 ((wq_completion)cgroup_destroy){+.+.}-{0:0}, at:
process_one_work+0x1f0/0x6f0
   #1: ffff80000b55bdc0
((work_completion)(&(&css->destroy_rwork)->work)){+.+.}-{0:0}, at:
process_one_work+0x1f0/0x6f0
   #2: ffff00004034e348 (&root->kernfs_rwsem){++++}-{3:3}, at:
__kernfs_remove+0x310/0x37c

  stack backtrace:
  CPU: 1 PID: 18 Comm: kworker/1:0 Not tainted 5.16.0-rc2+ #10984
  Hardware name: Raspberry Pi 4 Model B (DT)
  Workqueue: cgroup_destroy css_free_rwork_fn
  Call trace:
   dump_backtrace+0x0/0x1ac
   show_stack+0x18/0x24
   dump_stack_lvl+0x8c/0xb8
   dump_stack+0x18/0x34
   debug_check_no_locks_freed+0x124/0x140
   kfree+0xf0/0x3a4
   kernfs_put+0x1f8/0x224
   __kernfs_remove+0x1b8/0x37c
   kernfs_destroy_root+0x38/0x50
   css_free_rwork_fn+0x288/0x3d4
   process_one_work+0x288/0x6f0
   worker_thread+0x74/0x470
   kthread+0x188/0x194
   ret_from_fork+0x10/0x20

Since kernfs moves the kernfs_rwsem lock into root, it couldn't hold
the lock when the root node is tearing down. Thus, get the refcount
of root node.

Fixes: 393c371408 ("kernfs: switch global kernfs_rwsem lock to per-fs lock")
Reported-by: Marek Szyprowski <m.szyprowski@samsung.com>
Tested-by: Marek Szyprowski <m.szyprowski@samsung.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Link: https://lore.kernel.org/r/20211201231648.1027165-1-minchan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-12-03 14:36:21 +01:00
Minchan Kim
393c371408 kernfs: switch global kernfs_rwsem lock to per-fs lock
The kernfs implementation has big lock granularity(kernfs_rwsem) so
every kernfs-based(e.g., sysfs, cgroup) fs are able to compete the
lock. It makes trouble for some cases to wait the global lock
for a long time even though they are totally independent contexts
each other.

A general example is process A goes under direct reclaim with holding
the lock when it accessed the file in sysfs and process B is waiting
the lock with exclusive mode and then process C is waiting the lock
until process B could finish the job after it gets the lock from
process A.

This patch switches the global kernfs_rwsem to per-fs lock, which
put the rwsem into kernfs_root.

Suggested-by: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Link: https://lore.kernel.org/r/20211118230008.2679780-1-minchan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-11-24 13:55:16 +01:00
Ian Kent
410d591a19 kernfs: don't create a negative dentry if inactive node exists
It's been reported that doing stress test for module insertion and
removal can result in an ENOENT from libkmod for a valid module.

In kernfs_iop_lookup() a negative dentry is created if there's no kernfs
node associated with the dentry or the node is inactive.

But inactive kernfs nodes are meant to be invisible to the VFS and
creating a negative dentry for these can have unexpected side effects
when the node transitions to an active state.

The point of creating negative dentries is to avoid the expensive
alloc/free cycle that occurs if there are frequent lookups for kernfs
attributes that don't exist. So kernfs nodes that are not yet active
should not result in a negative dentry being created so when they
transition to an active state VFS lookups can create an associated
dentry is a natural way.

It's also been reported that https://github.com/osandov/blktests.git
test block/001 hangs during the test. It was suggested that recent
changes to blktests might have caused it but applying this patch
resolved the problem without change to blktests.

Fixes: c7e7c04274 ("kernfs: use VFS negative dentry caching")
Tested-by: Yi Zhang <yi.zhang@redhat.com>
ACKed-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ian Kent <raven@themaw.net>
Link: https://lore.kernel.org/r/163330943316.19450.15056895533949392922.stgit@mickey.themaw.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-10-04 10:27:18 +02:00
Hou Tao
df38d852c6 kernfs: also call kernfs_set_rev() for positive dentry
A KMSAN warning is reported by Alexander Potapenko:

BUG: KMSAN: uninit-value in kernfs_dop_revalidate+0x61f/0x840
fs/kernfs/dir.c:1053
 kernfs_dop_revalidate+0x61f/0x840 fs/kernfs/dir.c:1053
 d_revalidate fs/namei.c:854
 lookup_dcache fs/namei.c:1522
 __lookup_hash+0x3a6/0x590 fs/namei.c:1543
 filename_create+0x312/0x7c0 fs/namei.c:3657
 do_mkdirat+0x103/0x930 fs/namei.c:3900
 __do_sys_mkdir fs/namei.c:3931
 __se_sys_mkdir fs/namei.c:3929
 __x64_sys_mkdir+0xda/0x120 fs/namei.c:3929
 do_syscall_x64 arch/x86/entry/common.c:51

It seems a positive dentry in kernfs becomes a negative dentry directly
through d_delete() in vfs_rmdir(). dentry->d_time is uninitialized
when accessing it in kernfs_dop_revalidate(), because it is only
initialized when created as negative dentry in kernfs_iop_lookup().

The problem can be reproduced by the following command:

  cd /sys/fs/cgroup/pids && mkdir hi && stat hi && rmdir hi && stat hi

A simple fixes seems to be initializing d->d_time for positive dentry
in kernfs_iop_lookup() as well. The downside is the negative dentry
will be revalidated again after it becomes negative in d_delete(),
because the revison of its parent must have been increased due to
its removal.

Alternative solution is implement .d_iput for kernfs, and assign d_time
for the newly-generated negative dentry in it. But we may need to
take kernfs_rwsem to protect again the concurrent kernfs_link_sibling()
on the parent directory, it is a little over-killing. Now the simple
fix is chosen.

Link: https://marc.info/?l=linux-fsdevel&m=163249838610499
Fixes: c7e7c04274 ("kernfs: use VFS negative dentry caching")
Reported-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20210928140750.1274441-1-houtao1@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-09-28 18:18:15 +02:00
Ian Kent
df6192f47d kernfs: dont call d_splice_alias() under kernfs node lock
The call to d_splice_alias() in kernfs_iop_lookup() doesn't depend on
any kernfs node so there's no reason to hold the kernfs node lock when
calling it.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Link: https://lore.kernel.org/r/162642772000.63632.10672683419693513226.stgit@web.messagingengine.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-27 09:29:15 +02:00
Ian Kent
7ba0273b2f kernfs: switch kernfs to use an rwsem
The kernfs global lock restricts the ability to perform kernfs node
lookup operations in parallel during path walks.

Change the kernfs mutex to an rwsem so that, when opportunity arises,
node searches can be done in parallel with path walk lookups.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Link: https://lore.kernel.org/r/162642770946.63632.2218304587223241374.stgit@web.messagingengine.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-27 09:29:15 +02:00
Ian Kent
c7e7c04274 kernfs: use VFS negative dentry caching
If there are many lookups for non-existent paths these negative lookups
can lead to a lot of overhead during path walks.

The VFS allows dentries to be created as negative and hashed, and caches
them so they can be used to reduce the fairly high overhead alloc/free
cycle that occurs during these lookups.

Use the kernfs node parent revision to identify if a change has been
made to the containing directory so that the negative dentry can be
discarded and the lookup redone.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Link: https://lore.kernel.org/r/162642770420.63632.15791924970508867106.stgit@web.messagingengine.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-27 09:29:14 +02:00
Ian Kent
895adbec30 kernfs: add a revision to identify directory node changes
Add a revision counter to kernfs directory nodes so it can be used
to detect if a directory node has changed during negative dentry
revalidation.

There's an assumption that sizeof(unsigned long) <= sizeof(pointer)
on all architectures and as far as I know that assumption holds.

So adding a revision counter to the struct kernfs_elem_dir variant of
the kernfs_node type union won't increase the size of the kernfs_node
struct. This is because struct kernfs_elem_dir is at least
sizeof(pointer) smaller than the largest union variant. It's tempting
to make the revision counter a u64 but that would increase the size of
kernfs_node on archs where sizeof(pointer) is smaller than the revision
counter.

Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Signed-off-by: Ian Kent <raven@themaw.net>
Link: https://lore.kernel.org/r/162642769895.63632.8356662784964509867.stgit@web.messagingengine.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-07-27 09:29:14 +02:00
Ian Kent
d826e03651 kernfs: move revalidate to be near lookup
While the dentry operation kernfs_dop_revalidate() is grouped with
dentry type functions it also has a strong affinity to the inode
operation ->lookup().

It makes sense to locate this function near to kernfs_iop_lookup()
because we will be adding VFS negative dentry caching to reduce path
lookup overhead for non-existent paths.

There's no functional change from this patch.

Signed-off-by: Ian Kent <raven@themaw.net>
Reviewed-by: Miklos Szeredi <mszeredi@redhat.com>
Link: https://lore.kernel.org/r/162375275365.232295.8995526416263659926.stgit@web.messagingengine.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-06-15 17:04:32 +02:00
Christian Brauner
549c729771
fs: make helpers idmap mount aware
Extend some inode methods with an additional user namespace argument. A
filesystem that is aware of idmapped mounts will receive the user
namespace the mount has been marked with. This can be used for
additional permission checking and also to enable filesystems to
translate between uids and gids if they need to. We have implemented all
relevant helpers in earlier patches.

As requested we simply extend the exisiting inode method instead of
introducing new ones. This is a little more code churn but it's mostly
mechanical and doesnt't leave us with additional inode methods.

Link: https://lore.kernel.org/r/20210121131959.646623-25-christian.brauner@ubuntu.com
Cc: Christoph Hellwig <hch@lst.de>
Cc: David Howells <dhowells@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: linux-fsdevel@vger.kernel.org
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
2021-01-24 14:27:20 +01:00
Hui Su
0288e7fa35 fs/kernfs: remove the double check of dentry->inode
In both kernfs_node_from_dentry() and in
kernfs_dentry_node(), we will check the dentry->inode
is NULL or not, which is superfluous.

So remove the check in kernfs_node_from_dentry().

Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Hui Su <sh_def@163.com>
Link: https://lore.kernel.org/r/20201113132143.GA119541@rlk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-09 19:03:49 +01:00
Willem de Bruijn
21774fd81a kernfs: bring names in comments in line with code
Fix two stragglers in the comments of the below rename operation.

Fixes: adc5e8b58f ("kernfs: drop s_ prefix from kernfs_node members")
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Link: https://lore.kernel.org/r/20201015185726.1386868-1-willemdebruijn.kernel@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-09 18:12:39 +01:00
Mateusz Nosek
5bf33f04eb fs/kernfs/dir.c: Clean code by removing always true condition
Previously there was an additional check if variable pos is not null.
However, this check happens after entering while loop and only then,
which can happen only if pos is not null.
Therefore the additional check is redundant and can be removed.

Signed-off-by: Mateusz Nosek <mateusznosek0@gmail.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20191230191628.21099-1-mateusznosek0@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-14 16:14:47 +01:00
Linus Torvalds
168829ad09 Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull locking updates from Ingo Molnar:
 "The main changes in this cycle were:

   - A comprehensive rewrite of the robust/PI futex code's exit handling
     to fix various exit races. (Thomas Gleixner et al)

   - Rework the generic REFCOUNT_FULL implementation using
     atomic_fetch_* operations so that the performance impact of the
     cmpxchg() loops is mitigated for common refcount operations.

     With these performance improvements the generic implementation of
     refcount_t should be good enough for everybody - and this got
     confirmed by performance testing, so remove ARCH_HAS_REFCOUNT and
     REFCOUNT_FULL entirely, leaving the generic implementation enabled
     unconditionally. (Will Deacon)

   - Other misc changes, fixes, cleanups"

* 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
  lkdtm: Remove references to CONFIG_REFCOUNT_FULL
  locking/refcount: Remove unused 'refcount_error_report()' function
  locking/refcount: Consolidate implementations of refcount_t
  locking/refcount: Consolidate REFCOUNT_{MAX,SATURATED} definitions
  locking/refcount: Move saturation warnings out of line
  locking/refcount: Improve performance of generic REFCOUNT_FULL code
  locking/refcount: Move the bulk of the REFCOUNT_FULL implementation into the <linux/refcount.h> header
  locking/refcount: Remove unused refcount_*_checked() variants
  locking/refcount: Ensure integer operands are treated as signed
  locking/refcount: Define constants for saturation and max refcount values
  futex: Prevent exit livelock
  futex: Provide distinct return value when owner is exiting
  futex: Add mutex around futex exit
  futex: Provide state handling for exec() as well
  futex: Sanitize exit state handling
  futex: Mark the begin of futex exit explicitly
  futex: Set task::futex_state to DEAD right after handling futex exit
  futex: Split futex_mm_release() for exit/exec
  exit/exec: Seperate mm_release()
  futex: Replace PF_EXITPIDONE with a state
  ...
2019-11-26 16:02:40 -08:00
Tejun Heo
40430452fd kernfs: use 64bit inos if ino_t is 64bit
Each kernfs_node is identified with a 64bit ID.  The low 32bit is
exposed as ino and the high gen.  While this already allows using inos
as keys by looking up with wildcard generation number of 0, it's
adding unnecessary complications for 64bit ino archs which can
directly use kernfs_node IDs as inos to uniquely identify each cgroup
instance.

This patch exposes IDs directly as inos on 64bit ino archs.  The
conversion is mostly straight-forward.

* 32bit ino archs behave the same as before.  64bit ino archs now use
  the whole 64bit ID as ino and the generation number is fixed at 1.

* 64bit inos still use the same idr allocator which gurantees that the
  lower 32bits identify the current live instance uniquely and the
  high 32bits are incremented whenever the low bits wrap.  As the
  upper 32bits are no longer used as gen and we don't wanna start ino
  allocation with 33rd bit set, the initial value for highbits
  allocation is changed to 0 on 64bit ino archs.

* blktrace exposes two 32bit numbers - (INO,GEN) pair - to identify
  the issuing cgroup.  Userland builds FILEID_INO32_GEN fids from
  these numbers to look up the cgroups.  To remain compatible with the
  behavior, always output (LOW32,HIGH32) which will be constructed
  back to the original 64bit ID by __kernfs_fh_to_dentry().

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
2019-11-12 08:18:04 -08:00
Tejun Heo
fe0f726c9f kernfs: combine ino/id lookup functions into kernfs_find_and_get_node_by_id()
kernfs_find_and_get_node_by_ino() looks the kernfs_node matching the
specified ino.  On top of that, kernfs_get_node_by_id() and
kernfs_fh_get_inode() implement full ID matching by testing the rest
of ID.

On surface, confusingly, the two are slightly different in that the
latter uses 0 gen as wildcard while the former doesn't - does it mean
that the latter can't uniquely identify inodes w/ 0 gen?  In practice,
this is a distinction without a difference because generation number
starts at 1.  There are no actual IDs with 0 gen, so it can always
safely used as wildcard.

Let's simplify the code by renaming kernfs_find_and_get_node_by_ino()
to kernfs_find_and_get_node_by_id(), moving all lookup logics into it,
and removing now unnecessary kernfs_get_node_by_id().

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-11-12 08:18:04 -08:00
Tejun Heo
67c0496e87 kernfs: convert kernfs_node->id from union kernfs_node_id to u64
kernfs_node->id is currently a union kernfs_node_id which represents
either a 32bit (ino, gen) pair or u64 value.  I can't see much value
in the usage of the union - all that's needed is a 64bit ID which the
current code is already limited to.  Using a union makes the code
unnecessarily complicated and prevents using 64bit ino without adding
practical benefits.

This patch drops union kernfs_node_id and makes kernfs_node->id a u64.
ino is stored in the lower 32bits and gen upper.  Accessors -
kernfs[_id]_ino() and kernfs[_id]_gen() - are added to retrieve the
ino and gen.  This simplifies ID handling less cumbersome and will
allow using 64bit inos on supported archs.

This patch doesn't make any functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Alexei Starovoitov <ast@kernel.org>
2019-11-12 08:18:03 -08:00
Tejun Heo
880df13161 kernfs: kernfs_find_and_get_node_by_ino() should only look up activated nodes
kernfs node can be created in two separate steps - allocation and
activation.  This is used to make kernfs nodes visible only after the
internal states attached to the node are fully initialized.
kernfs_find_and_get_node_by_id() currently allows lookups of nodes
which aren't activated yet and thus can expose nodes are which are
still being prepped by kernfs users.

Fix it by disallowing lookups of nodes which aren't activated yet.

kernfs_find_and_get_node_by_ino()

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
2019-11-12 08:18:03 -08:00
Tejun Heo
b680b08171 kernfs: use dumber locking for kernfs_find_and_get_node_by_ino()
kernfs_find_and_get_node_by_ino() uses RCU protection.  It's currently
a bit buggy because it can look up a node which hasn't been activated
yet and thus may end up exposing a node that the kernfs user is still
prepping.

While it can be fixed by pushing it further in the current direction,
it's already complicated and isn't clear whether the complexity is
justified.  The main use of kernfs_find_and_get_node_by_ino() is for
exportfs operations.  They aren't super hot and all the follow-up
operations (e.g. mapping to path) use normal locking anyway.

Let's switch to a dumber locking scheme and protect the lookup with
kernfs_idr_lock.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
2019-11-12 08:18:03 -08:00
Tejun Heo
e23f568aa6 kernfs: fix ino wrap-around detection
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 <tj@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Fixes: 4a3ef68aca ("kernfs: implement i_generation")
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: stable@vger.kernel.org # v4.14+
2019-11-12 08:18:03 -08:00
Qian Cai
5facae4f35 locking/lockdep: Remove unused @nested argument from lock_release()
Since the following commit:

  b4adfe8e05 ("locking/lockdep: Remove unused argument in __lock_release")

@nested is no longer used in lock_release(), so remove it from all
lock_release() calls and friends.

Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will@kernel.org>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: airlied@linux.ie
Cc: akpm@linux-foundation.org
Cc: alexander.levin@microsoft.com
Cc: daniel@iogearbox.net
Cc: davem@davemloft.net
Cc: dri-devel@lists.freedesktop.org
Cc: duyuyang@gmail.com
Cc: gregkh@linuxfoundation.org
Cc: hannes@cmpxchg.org
Cc: intel-gfx@lists.freedesktop.org
Cc: jack@suse.com
Cc: jlbec@evilplan.or
Cc: joonas.lahtinen@linux.intel.com
Cc: joseph.qi@linux.alibaba.com
Cc: jslaby@suse.com
Cc: juri.lelli@redhat.com
Cc: maarten.lankhorst@linux.intel.com
Cc: mark@fasheh.com
Cc: mhocko@kernel.org
Cc: mripard@kernel.org
Cc: ocfs2-devel@oss.oracle.com
Cc: rodrigo.vivi@intel.com
Cc: sean@poorly.run
Cc: st@kernel.org
Cc: tj@kernel.org
Cc: tytso@mit.edu
Cc: vdavydov.dev@gmail.com
Cc: vincent.guittot@linaro.org
Cc: viro@zeniv.linux.org.uk
Link: https://lkml.kernel.org/r/1568909380-32199-1-git-send-email-cai@lca.pw
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2019-10-09 12:46:10 +02:00
Jia-Ju Bai
bbe70e4e42 fs: kernfs: Fix possible null-pointer dereferences in kernfs_path_from_node_locked()
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 <baijiaju1990@gmail.com>
Link: https://lore.kernel.org/r/20190724022242.27505-1-baijiaju1990@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-07-25 15:32:51 +02:00
Peng Wang
2fd60da46d kernfs: fix potential null pointer dereference
Get root safely after kn is ensureed to be not null.

Signed-off-by: Peng Wang <rocking@whu.edu.cn>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20190708151611.13242-1-rocking@whu.edu.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-07-25 15:30:48 +02:00
Thomas Gleixner
55716d2643 treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 428
Based on 1 normalized pattern(s):

  this file is released under the gplv2

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-only

has been chosen to replace the boilerplate/reference in 68 file(s).

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Armijn Hemel <armijn@tjaldur.nl>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190531190114.292346262@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-05 17:37:16 +02:00
Linus Torvalds
f72dae2089 selinux/stable-5.2 PR 20190507
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Merge tag 'selinux-pr-20190507' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:
 "We've got a few SELinux patches for the v5.2 merge window, the
  highlights are below:

   - Add LSM hooks, and the SELinux implementation, for proper labeling
     of kernfs. While we are only including the SELinux implementation
     here, the rest of the LSM folks have given the hooks a thumbs-up.

   - Update the SELinux mdp (Make Dummy Policy) script to actually work
     on a modern system.

   - Disallow userspace to change the LSM credentials via
     /proc/self/attr when the task's credentials are already overridden.

     The change was made in procfs because all the LSM folks agreed this
     was the Right Thing To Do and duplicating it across each LSM was
     going to be annoying"

* tag 'selinux-pr-20190507' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  proc: prevent changes to overridden credentials
  selinux: Check address length before reading address family
  kernfs: fix xattr name handling in LSM helpers
  MAINTAINERS: update SELinux file patterns
  selinux: avoid uninitialized variable warning
  selinux: remove useless assignments
  LSM: lsm_hooks.h - fix missing colon in docstring
  selinux: Make selinux_kernfs_init_security static
  kernfs: initialize security of newly created nodes
  selinux: implement the kernfs_init_security hook
  LSM: add new hook for kernfs node initialization
  kernfs: use simple_xattrs for security attributes
  selinux: try security xattr after genfs for kernfs filesystems
  kernfs: do not alloc iattrs in kernfs_xattr_get
  kernfs: clean up struct kernfs_iattrs
  scripts/selinux: fix build
  selinux: use kernel linux/socket.h for genheaders and mdp
  scripts/selinux: modernize mdp
2019-05-07 18:48:09 -07:00
Andrea Parri
998267900c kernfs: fix barrier usage in __kernfs_new_node()
smp_mb__before_atomic() can not be applied to atomic_set().  Remove the
barrier and rely on RELEASE synchronization.

Fixes: ba16b2846a ("kernfs: add an API to get kernfs node from inode number")
Cc: stable@vger.kernel.org
Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-25 21:41:35 +02:00
Ondrej Mosnacek
e19dfdc83b kernfs: initialize security of newly created nodes
Use the new security_kernfs_init_security() hook to allow LSMs to
possibly assign a non-default security context to a newly created kernfs
node based on the attributes of the new node and also its parent node.

This fixes an issue with cgroupfs under SELinux, where newly created
cgroup subdirectories/files would not inherit its parent's context if
it had been set explicitly to a non-default value (other than the genfs
context specified by the policy). This can be reproduced as follows (on
Fedora/RHEL):

    # mkdir /sys/fs/cgroup/unified/test
    # # Need permissive to change the label under Fedora policy:
    # setenforce 0
    # chcon -t container_file_t /sys/fs/cgroup/unified/test
    # ls -lZ /sys/fs/cgroup/unified
    total 0
    -r--r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.controllers
    -rw-r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.max.depth
    -rw-r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.max.descendants
    -rw-r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.procs
    -r--r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.stat
    -rw-r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.subtree_control
    -rw-r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.threads
    drwxr-xr-x.  2 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 init.scope
    drwxr-xr-x. 26 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:21 system.slice
    drwxr-xr-x.  3 root root system_u:object_r:container_file_t:s0 0 Jan 29 03:15 test
    drwxr-xr-x.  3 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 user.slice
    # mkdir /sys/fs/cgroup/unified/test/subdir

Actual result:

    # ls -ldZ /sys/fs/cgroup/unified/test/subdir
    drwxr-xr-x. 2 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:15 /sys/fs/cgroup/unified/test/subdir

Expected result:

    # ls -ldZ /sys/fs/cgroup/unified/test/subdir
    drwxr-xr-x. 2 root root unconfined_u:object_r:container_file_t:s0 0 Jan 29 03:15 /sys/fs/cgroup/unified/test/subdir

Link: https://github.com/SELinuxProject/selinux-kernel/issues/39

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-03-20 22:10:15 -04:00
Ondrej Mosnacek
0ac6075a32 kernfs: use simple_xattrs for security attributes
Replace the special handling of security xattrs with simple_xattrs, as
is already done for the trusted xattrs. This simplifies the code and
allows LSMs to use more than just a single xattr to do their business.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: manual merge fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-03-20 21:54:33 -04:00
Ondrej Mosnacek
0589521962 kernfs: clean up struct kernfs_iattrs
Right now, kernfs_iattrs embeds the whole struct iattr, even though it
doesn't really use half of its fields... This both leads to wasting
space and makes the code look awkward. Let's just list the few fields
we need directly in struct kernfs_iattrs.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: merged a number of chunks manually due to fuzz]
Signed-off-by: Paul Moore <paul@paul-moore.com>
2019-03-20 21:42:14 -04:00
Ayush Mittal
26e28d68b1 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>
2019-02-08 12:57:32 +01:00
Dmitry Torokhov
488dee96bb kernfs: allow creating kernfs objects with arbitrary uid/gid
This change allows creating kernfs files and directories with arbitrary
uid/gid instead of always using GLOBAL_ROOT_UID/GID by extending
kernfs_create_dir_ns() and kernfs_create_file_ns() with uid/gid arguments.
The "simple" kernfs_create_file() and kernfs_create_dir() are left alone
and always create objects belonging to the global root.

When creating symlinks ownership (uid/gid) is taken from the target kernfs
object.

Co-Developed-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Tyler Hicks <tyhicks@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2018-07-20 23:44:35 -07:00
Deepa Dinamani
95582b0083 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>
2018-06-05 16:57:31 -07:00
Shaohua Li
c53cd490b1 kernfs: introduce kernfs_node_id
inode number and generation can identify a kernfs node. We are going to
export the identification by exportfs operations, so put ino and
generation into a separate structure. It's convenient when later patches
use the identification.

Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-29 09:00:03 -06:00
Shaohua Li
319ba91d35 kernfs: don't set dentry->d_fsdata
When working on adding exportfs operations in kernfs, I found it's hard
to initialize dentry->d_fsdata in the exportfs operations. Looks there
is no way to do it without race condition. Look at the kernfs code
closely, there is no point to set dentry->d_fsdata. inode->i_private
already points to kernfs_node, and we can get inode from a dentry. So
this patch just delete the d_fsdata usage.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-29 09:00:03 -06:00
Shaohua Li
ba16b2846a kernfs: add an API to get kernfs node from inode number
Add an API to get kernfs node from inode number. We will need this to
implement exportfs operations.

This API will be used in blktrace too later, so it should be as fast as
possible. To make the API lock free, kernfs node is freed in RCU
context. And we depend on kernfs_node count/ino number to filter out
stale kernfs nodes.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-29 09:00:03 -06:00
Shaohua Li
4a3ef68aca kernfs: implement i_generation
Set i_generation for kernfs inode. This is required to implement
exportfs operations. The generation is 32-bit, so it's possible the
generation wraps up and we find stale files. To reduce the posssibility,
we don't reuse inode numer immediately. When the inode number allocation
wraps, we increase generation number. In this way generation/inode
number consist of a 64-bit number which is unlikely duplicated. This
does make the idr tree more sparse and waste some memory. Since idr
manages 32-bit keys, idr uses a 6-level radix tree, each level covers 6
bits of the key. In a 100k inode kernfs, the worst case will have around
300k radix tree node. Each node is 576bytes, so the tree will use about
~150M memory. Sounds not too bad, if this really is a problem, we should
find better data structure.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-29 09:00:03 -06:00
Shaohua Li
7d35079f82 kernfs: use idr instead of ida to manage inode number
kernfs uses ida to manage inode number. The problem is we can't get
kernfs_node from inode number with ida. Switching to use idr, next patch
will add an API to get kernfs_node from inode number.

Acked-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2017-07-29 09:00:03 -06:00
Linus Torvalds
f7878dc3a9 Merge branch 'for-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
 "Several noteworthy changes.

   - Parav's rdma controller is finally merged. It is very straight
     forward and can limit the abosolute numbers of common rdma
     constructs used by different cgroups.

   - kernel/cgroup.c got too chubby and disorganized. Created
     kernel/cgroup/ subdirectory and moved all cgroup related files
     under kernel/ there and reorganized the core code. This hurts for
     backporting patches but was long overdue.

   - cgroup v2 process listing reimplemented so that it no longer
     depends on allocating a buffer large enough to cache the entire
     result to sort and uniq the output. v2 has always mangled the sort
     order to ensure that users don't depend on the sorted output, so
     this shouldn't surprise anybody. This makes the pid listing
     functions use the same iterators that are used internally, which
     have to have the same iterating capabilities anyway.

   - perf cgroup filtering now works automatically on cgroup v2. This
     patch was posted a long time ago but somehow fell through the
     cracks.

   - misc fixes asnd documentation updates"

* 'for-4.11' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (27 commits)
  kernfs: fix locking around kernfs_ops->release() callback
  cgroup: drop the matching uid requirement on migration for cgroup v2
  cgroup, perf_event: make perf_event controller work on cgroup2 hierarchy
  cgroup: misc cleanups
  cgroup: call subsys->*attach() only for subsystems which are actually affected by migration
  cgroup: track migration context in cgroup_mgctx
  cgroup: cosmetic update to cgroup_taskset_add()
  rdmacg: Fixed uninitialized current resource usage
  cgroup: Add missing cgroup-v2 PID controller documentation.
  rdmacg: Added documentation for rdmacg
  IB/core: added support to use rdma cgroup controller
  rdmacg: Added rdma cgroup controller
  cgroup: fix a comment typo
  cgroup: fix RCU related sparse warnings
  cgroup: move namespace code to kernel/cgroup/namespace.c
  cgroup: rename functions for consistency
  cgroup: move v1 mount functions to kernel/cgroup/cgroup-v1.c
  cgroup: separate out cgroup1_kf_syscall_ops
  cgroup: refactor mount path and clearly distinguish v1 and v2 paths
  cgroup: move cgroup v1 specific code to kernel/cgroup/cgroup-v1.c
  ...
2017-02-27 21:41:08 -08:00
Konstantin Khlebnikov
17627157cd kernfs: handle null pointers while printing node name and path
Null kernfs nodes could be found at cgroups during construction.
It seems safer to handle these null pointers right in kernfs in
the same way as printf prints "(null)" for null pointer string.

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-02-10 16:02:26 +01:00
Tejun Heo
0e67db2f9f kernfs: add kernfs_ops->open/release() callbacks
Add ->open/release() methods to kernfs_ops.  ->open() is called when
the file is opened and ->release() when the file is either released or
severed.  These callbacks can be used, for example, to manage
persistent caching objects over multiple seq_file iterations.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Acked-by: Zefan Li <lizefan@huawei.com>
2016-12-27 14:49:03 -05:00