Commit Graph

156 Commits

Author SHA1 Message Date
Muchun Song
30480b988f kernfs: fix missing kernfs_idr_lock to remove an ID from the IDR
The root->ino_idr is supposed to be protected by kernfs_idr_lock, fix
it.

Fixes: 488dee96bb ("kernfs: allow creating kernfs objects with arbitrary uid/gid")
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20230523024017.24851-1-songmuchun@bytedance.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-05-31 19:03:49 +01:00
Linus Torvalds
556eb8b791 Driver core changes for 6.4-rc1
Here is the large set of driver core changes for 6.4-rc1.
 
 Once again, a busy development cycle, with lots of changes happening in
 the driver core in the quest to be able to move "struct bus" and "struct
 class" into read-only memory, a task now complete with these changes.
 
 This will make the future rust interactions with the driver core more
 "provably correct" as well as providing more obvious lifetime rules for
 all busses and classes in the kernel.
 
 The changes required for this did touch many individual classes and
 busses as many callbacks were changed to take const * parameters
 instead.  All of these changes have been submitted to the various
 subsystem maintainers, giving them plenty of time to review, and most of
 them actually did so.
 
 Other than those changes, included in here are a small set of other
 things:
   - kobject logging improvements
   - cacheinfo improvements and updates
   - obligatory fw_devlink updates and fixes
   - documentation updates
   - device property cleanups and const * changes
   - firwmare loader dependency fixes.
 
 All of these have been in linux-next for a while with no reported
 problems.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the large set of driver core changes for 6.4-rc1.

  Once again, a busy development cycle, with lots of changes happening
  in the driver core in the quest to be able to move "struct bus" and
  "struct class" into read-only memory, a task now complete with these
  changes.

  This will make the future rust interactions with the driver core more
  "provably correct" as well as providing more obvious lifetime rules
  for all busses and classes in the kernel.

  The changes required for this did touch many individual classes and
  busses as many callbacks were changed to take const * parameters
  instead. All of these changes have been submitted to the various
  subsystem maintainers, giving them plenty of time to review, and most
  of them actually did so.

  Other than those changes, included in here are a small set of other
  things:

   - kobject logging improvements

   - cacheinfo improvements and updates

   - obligatory fw_devlink updates and fixes

   - documentation updates

   - device property cleanups and const * changes

   - firwmare loader dependency fixes.

  All of these have been in linux-next for a while with no reported
  problems"

* tag 'driver-core-6.4-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (120 commits)
  device property: make device_property functions take const device *
  driver core: update comments in device_rename()
  driver core: Don't require dynamic_debug for initcall_debug probe timing
  firmware_loader: rework crypto dependencies
  firmware_loader: Strip off \n from customized path
  zram: fix up permission for the hot_add sysfs file
  cacheinfo: Add use_arch[|_cache]_info field/function
  arch_topology: Remove early cacheinfo error message if -ENOENT
  cacheinfo: Check cache properties are present in DT
  cacheinfo: Check sib_leaf in cache_leaves_are_shared()
  cacheinfo: Allow early level detection when DT/ACPI info is missing/broken
  cacheinfo: Add arm64 early level initializer implementation
  cacheinfo: Add arch specific early level initializer
  tty: make tty_class a static const structure
  driver core: class: remove struct class_interface * from callbacks
  driver core: class: mark the struct class in struct class_interface constant
  driver core: class: make class_register() take a const *
  driver core: class: mark class_release() as taking a const *
  driver core: remove incorrect comment for device_create*
  MIPS: vpe-cmp: remove module owner pointer from struct class usage.
  ...
2023-04-27 11:53:57 -07:00
Jeff Layton
364595a685
fs: consolidate duplicate dt_type helpers
There are three copies of the same dt_type helper sprinkled around the
tree. Convert them to use the common fs_umode_to_dtype function instead,
which has the added advantage of properly returning DT_UNKNOWN when
given a mode that contains an unrecognized type.

Cc: Chuck Lever <chuck.lever@oracle.com>
Cc: Phillip Potter <phil@philpotter.co.uk>
Suggested-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Message-Id: <20230330104144.75547-1-jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-04-03 09:23:54 +02:00
Imran Khan
06fb473613 kernfs: change kernfs_rename_lock into a read-write lock.
kernfs_rename_lock protects a node's ->parent and thus kernfs topology.
Thus it can be used in cases that rely on a stable kernfs topology.
Change it to a read-write lock for better scalability.

Suggested by: Al Viro <viro@zeniv.linux.org.uk>

Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20230309110932.2889010-4-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-29 12:23:45 +02:00
Imran Khan
c9f2dfb7b5 kernfs: Use a per-fs rwsem to protect per-fs list of kernfs_super_info.
Right now per-fs kernfs_rwsem protects list of kernfs_super_info instances
for a kernfs_root. Since kernfs_rwsem is used to synchronize several other
operations across kernfs and since most of these operations don't impact
kernfs_super_info, we can use a separate per-fs rwsem to synchronize access
to list of kernfs_super_info.
This helps in reducing contention around kernfs_rwsem and also allows
operations that change/access list of kernfs_super_info to proceed without
contending for kernfs_rwsem.

Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20230309110932.2889010-3-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-29 12:23:45 +02:00
Imran Khan
9caf696142 kernfs: Introduce separate rwsem to protect inode attributes.
Right now a global per-fs rwsem (kernfs_rwsem) synchronizes multiple
kernfs operations. On a large system with few hundred CPUs and few
hundred applications simultaneoulsy trying to access sysfs, this
results in multiple sys_open(s) contending on kernfs_rwsem via
kernfs_iop_permission and kernfs_dop_revalidate.

For example on a system with 384 cores, if I run 200 instances of an
application which is mostly executing the following loop:

  for (int loop = 0; loop <100 ; loop++)
  {
    for (int port_num = 1; port_num < 2; port_num++)
    {
      for (int gid_index = 0; gid_index < 254; gid_index++ )
      {
        char ret_buf[64], ret_buf_lo[64];
        char gid_file_path[1024];

        int      ret_len;
        int      ret_fd;
        ssize_t  ret_rd;

        ub4  i, saved_errno;

        memset(ret_buf, 0, sizeof(ret_buf));
        memset(gid_file_path, 0, sizeof(gid_file_path));

        ret_len = snprintf(gid_file_path, sizeof(gid_file_path),
                           "/sys/class/infiniband/%s/ports/%d/gids/%d",
                           dev_name,
                           port_num,
                           gid_index);

        ret_fd = open(gid_file_path, O_RDONLY | O_CLOEXEC);
        if (ret_fd < 0)
        {
          printf("Failed to open %s\n", gid_file_path);
          continue;
        }

        /* Read the GID */
        ret_rd = read(ret_fd, ret_buf, 40);

        if (ret_rd == -1)
        {
          printf("Failed to read from file %s, errno: %u\n",
                 gid_file_path, saved_errno);

          continue;
        }

        close(ret_fd);
      }
    }

I see contention around kernfs_rwsem as follows:

path_openat
|
|----link_path_walk.part.0.constprop.0
|      |
|      |--49.92%--inode_permission
|      |          |
|      |           --48.69%--kernfs_iop_permission
|      |                     |
|      |                     |--18.16%--down_read
|      |                     |
|      |                     |--15.38%--up_read
|      |                     |
|      |                      --14.58%--_raw_spin_lock
|      |                                |
|      |                                 -----
|      |
|      |--29.08%--walk_component
|      |          |
|      |           --29.02%--lookup_fast
|      |                     |
|      |                     |--24.26%--kernfs_dop_revalidate
|      |                     |          |
|      |                     |          |--14.97%--down_read
|      |                     |          |
|      |                     |           --9.01%--up_read
|      |                     |
|      |                      --4.74%--__d_lookup
|      |                                |
|      |                                 --4.64%--_raw_spin_lock
|      |                                           |
|      |                                            ----

Having a separate per-fs rwsem to protect kernfs inode attributes,
will avoid the above mentioned contention and result in better
performance as can bee seen below:

path_openat
|
|----link_path_walk.part.0.constprop.0
|     |
|     |
|     |--27.06%--inode_permission
|     |          |
|     |           --25.84%--kernfs_iop_permission
|     |                     |
|     |                     |--9.29%--up_read
|     |                     |
|     |                     |--8.19%--down_read
|     |                     |
|     |                      --7.89%--_raw_spin_lock
|     |                                |
|     |                                 ----
|     |
|     |--22.42%--walk_component
|     |          |
|     |           --22.36%--lookup_fast
|     |                     |
|     |                     |--16.07%--__d_lookup
|     |                     |          |
|     |                     |           --16.01%--_raw_spin_lock
|     |                     |                     |
|     |                     |                      ----
|     |                     |
|     |                      --6.28%--kernfs_dop_revalidate
|     |                                |
|     |                                |--3.76%--down_read
|     |                                |
|     |                                 --2.26%--up_read

As can be seen from the above data the overhead due to both
kerfs_iop_permission and kernfs_dop_revalidate have gone down and
this also reduces overall run time of the earlier mentioned loop.

Signed-off-by: Imran Khan <imran.f.khan@oracle.com>
Link: https://lore.kernel.org/r/20230309110932.2889010-2-imran.f.khan@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-03-29 12:23:45 +02:00
Linus Torvalds
a93e884edf Driver core changes for 6.3-rc1
Here is the large set of driver core changes for 6.3-rc1.
 
 There's a lot of changes this development cycle, most of the work falls
 into two different categories:
   - fw_devlink fixes and updates.  This has gone through numerous review
     cycles and lots of review and testing by lots of different devices.
     Hopefully all should be good now, and Saravana will be keeping a
     watch for any potential regression on odd embedded systems.
   - driver core changes to work to make struct bus_type able to be moved
     into read-only memory (i.e. const)  The recent work with Rust has
     pointed out a number of areas in the driver core where we are
     passing around and working with structures that really do not have
     to be dynamic at all, and they should be able to be read-only making
     things safer overall.  This is the contuation of that work (started
     last release with kobject changes) in moving struct bus_type to be
     constant.  We didn't quite make it for this release, but the
     remaining patches will be finished up for the release after this
     one, but the groundwork has been laid for this effort.
 
 Other than that we have in here:
   - debugfs memory leak fixes in some subsystems
   - error path cleanups and fixes for some never-able-to-be-hit
     codepaths.
   - cacheinfo rework and fixes
   - Other tiny fixes, full details are in the shortlog
 
 All of these have been in linux-next for a while with no reported
 problems.
 
 Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Merge tag 'driver-core-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core

Pull driver core updates from Greg KH:
 "Here is the large set of driver core changes for 6.3-rc1.

  There's a lot of changes this development cycle, most of the work
  falls into two different categories:

   - fw_devlink fixes and updates. This has gone through numerous review
     cycles and lots of review and testing by lots of different devices.
     Hopefully all should be good now, and Saravana will be keeping a
     watch for any potential regression on odd embedded systems.

   - driver core changes to work to make struct bus_type able to be
     moved into read-only memory (i.e. const) The recent work with Rust
     has pointed out a number of areas in the driver core where we are
     passing around and working with structures that really do not have
     to be dynamic at all, and they should be able to be read-only
     making things safer overall. This is the contuation of that work
     (started last release with kobject changes) in moving struct
     bus_type to be constant. We didn't quite make it for this release,
     but the remaining patches will be finished up for the release after
     this one, but the groundwork has been laid for this effort.

  Other than that we have in here:

   - debugfs memory leak fixes in some subsystems

   - error path cleanups and fixes for some never-able-to-be-hit
     codepaths.

   - cacheinfo rework and fixes

   - Other tiny fixes, full details are in the shortlog

  All of these have been in linux-next for a while with no reported
  problems"

[ Geert Uytterhoeven points out that that last sentence isn't true, and
  that there's a pending report that has a fix that is queued up - Linus ]

* tag 'driver-core-6.3-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core: (124 commits)
  debugfs: drop inline constant formatting for ERR_PTR(-ERROR)
  OPP: fix error checking in opp_migrate_dentry()
  debugfs: update comment of debugfs_rename()
  i3c: fix device.h kernel-doc warnings
  dma-mapping: no need to pass a bus_type into get_arch_dma_ops()
  driver core: class: move EXPORT_SYMBOL_GPL() lines to the correct place
  Revert "driver core: add error handling for devtmpfs_create_node()"
  Revert "devtmpfs: add debug info to handle()"
  Revert "devtmpfs: remove return value of devtmpfs_delete_node()"
  driver core: cpu: don't hand-override the uevent bus_type callback.
  devtmpfs: remove return value of devtmpfs_delete_node()
  devtmpfs: add debug info to handle()
  driver core: add error handling for devtmpfs_create_node()
  driver core: bus: update my copyright notice
  driver core: bus: add bus_get_dev_root() function
  driver core: bus: constify bus_unregister()
  driver core: bus: constify some internal functions
  driver core: bus: constify bus_get_kset()
  driver core: bus: constify bus_register/unregister_notifier()
  driver core: remove private pointer from struct bus_type
  ...
2023-02-24 12:58:55 -08:00
Zhen Lei
95b2a03478 kernfs: remove an unused if statement in kernfs_path_from_node_locked()
It makes no sense to call kernfs_path_from_node_locked() with NULL buf,
and no one is doing that right now.

Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20221126111634.1994-1-thunder.leizhen@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2023-01-19 17:13:24 +01:00
Christian Brauner
e18275ae55
fs: port ->rename() to pass mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:26 +01:00
Christian Brauner
c54bd91e9e
fs: port ->mkdir() to pass mnt_idmap
Convert to struct mnt_idmap.

Last cycle we merged the necessary infrastructure in
256c8aed2b ("fs: introduce dedicated idmap type for mounts").
This is just the conversion to struct mnt_idmap.

Currently we still pass around the plain namespace that was attached to a
mount. This is in general pretty convenient but it makes it easy to
conflate namespaces that are relevant on the filesystem with namespaces
that are relevent on the mount level. Especially for non-vfs developers
without detailed knowledge in this area this can be a potential source for
bugs.

Once the conversion to struct mnt_idmap is done all helpers down to the
really low-level helpers will take a struct mnt_idmap argument instead of
two namespace arguments. This way it becomes impossible to conflate the two
eliminating the possibility of any bugs. All of the vfs and all filesystems
only operate on struct mnt_idmap.

Acked-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Christian Brauner (Microsoft) <brauner@kernel.org>
2023-01-19 09:24:26 +01:00
Randy Dunlap
24b3e3dd9c kernfs: fix all kernel-doc warnings and multiple typos
Fix kernel-doc warnings. Many of these are about a function's
return value, so use the kernel-doc Return: format to fix those

Use % prefix on numeric constant values.

dir.c: fix typos/spellos
file.c fix typo: s/taret/target/

Fix all of these kernel-doc warnings:

dir.c:305: warning: missing initial short description on line:
 *      kernfs_name_hash

dir.c:137: warning: No description found for return value of 'kernfs_path_from_node_locked'
dir.c:196: warning: No description found for return value of 'kernfs_name'
dir.c:224: warning: No description found for return value of 'kernfs_path_from_node'
dir.c:292: warning: No description found for return value of 'kernfs_get_parent'
dir.c:312: warning: No description found for return value of 'kernfs_name_hash'
dir.c:404: warning: No description found for return value of 'kernfs_unlink_sibling'
dir.c:588: warning: No description found for return value of 'kernfs_node_from_dentry'
dir.c:806: warning: No description found for return value of 'kernfs_find_ns'
dir.c:879: warning: No description found for return value of 'kernfs_find_and_get_ns'
dir.c:904: warning: No description found for return value of 'kernfs_walk_and_get_ns'
dir.c:927: warning: No description found for return value of 'kernfs_create_root'
dir.c:996: warning: No description found for return value of 'kernfs_root_to_node'
dir.c:1016: warning: No description found for return value of 'kernfs_create_dir_ns'
dir.c:1048: warning: No description found for return value of 'kernfs_create_empty_dir'
dir.c:1306: warning: No description found for return value of 'kernfs_next_descendant_post'
dir.c:1568: warning: No description found for return value of 'kernfs_remove_self'
dir.c:1630: warning: No description found for return value of 'kernfs_remove_by_name_ns'
dir.c:1667: warning: No description found for return value of 'kernfs_rename_ns'

file.c:66: warning: No description found for return value of 'of_on'
file.c:88: warning: No description found for return value of 'kernfs_deref_open_node_locked'
file.c:1036: warning: No description found for return value of '__kernfs_create_file'

inode.c💯 warning: No description found for return value of 'kernfs_setattr'

mount.c:160: warning: No description found for return value of 'kernfs_root_from_sb'
mount.c:198: warning: No description found for return value of 'kernfs_node_dentry'
mount.c:302: warning: No description found for return value of 'kernfs_super_ns'
mount.c:318: warning: No description found for return value of 'kernfs_get_tree'

symlink.c:28: warning: No description found for return value of 'kernfs_create_link'

Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://lore.kernel.org/r/20221112031456.22980-1-rdunlap@infradead.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-23 19:28:26 +01:00
Greg Kroah-Hartman
05df6ab8eb Merge 6.1-rc6 into driver-core-next
We need the kernfs changes in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-21 10:21:53 +01:00
Tejun Heo
1edfe4ea16 kernfs: Fix spurious lockdep warning in kernfs_find_and_get_node_by_id()
c25491747b ("kernfs: Add KERNFS_REMOVING flags") made
kernfs_find_and_get_node_by_id() test kernfs_active() instead of
KERNFS_ACTIVATED. kernfs_find_and_get_by_id() is called without holding the
kernfs_rwsem triggering the following lockdep warning.

  WARNING: CPU: 1 PID: 6191 at fs/kernfs/dir.c:36 kernfs_active+0xe8/0x120 fs/kernfs/dir.c:38
  Modules linked in:
  CPU: 1 PID: 6191 Comm: syz-executor.1 Not tainted 6.0.0-syzkaller-09413-g4899a36f91a9 #0
  Hardware name: linux,dummy-virt (DT)
  pstate: 10000005 (nzcV daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  pc : kernfs_active+0xe8/0x120 fs/kernfs/dir.c:36
  lr : lock_is_held include/linux/lockdep.h:283 [inline]
  lr : kernfs_active+0x94/0x120 fs/kernfs/dir.c:36
  sp : ffff8000182c7a00
  x29: ffff8000182c7a00 x28: 0000000000000002 x27: 0000000000000001
  x26: ffff00000ee1f6a8 x25: 1fffe00001dc3ed5 x24: 0000000000000000
  x23: ffff80000ca1fba0 x22: ffff8000089efcb0 x21: 0000000000000001
  x20: ffff0000091181d0 x19: ffff0000091181d0 x18: ffff00006a9e6b88
  x17: 0000000000000000 x16: 0000000000000000 x15: ffff00006a9e6bc4
  x14: 1ffff00003058f0e x13: 1fffe0000258c816 x12: ffff700003058f39
  x11: 1ffff00003058f38 x10: ffff700003058f38 x9 : dfff800000000000
  x8 : ffff80000e482f20 x7 : ffff0000091d8058 x6 : ffff80000e482c60
  x5 : ffff000009402ee8 x4 : 1ffff00001bd1f46 x3 : 1fffe0000258c6d1
  x2 : 0000000000000003 x1 : 00000000000000c0 x0 : 0000000000000000
  Call trace:
   kernfs_active+0xe8/0x120 fs/kernfs/dir.c:38
   kernfs_find_and_get_node_by_id+0x6c/0x140 fs/kernfs/dir.c:708
   __kernfs_fh_to_dentry fs/kernfs/mount.c:102 [inline]
   kernfs_fh_to_dentry+0x88/0x1fc fs/kernfs/mount.c:128
   exportfs_decode_fh_raw+0x104/0x560 fs/exportfs/expfs.c:435
   exportfs_decode_fh+0x10/0x5c fs/exportfs/expfs.c:575
   do_handle_to_path fs/fhandle.c:152 [inline]
   handle_to_path fs/fhandle.c:207 [inline]
   do_handle_open+0x2a4/0x7b0 fs/fhandle.c:223
   __do_compat_sys_open_by_handle_at fs/fhandle.c:277 [inline]
   __se_compat_sys_open_by_handle_at fs/fhandle.c:274 [inline]
   __arm64_compat_sys_open_by_handle_at+0x6c/0x9c fs/fhandle.c:274
   __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
   invoke_syscall+0x6c/0x260 arch/arm64/kernel/syscall.c:52
   el0_svc_common.constprop.0+0xc4/0x254 arch/arm64/kernel/syscall.c:142
   do_el0_svc_compat+0x40/0x70 arch/arm64/kernel/syscall.c:212
   el0_svc_compat+0x54/0x140 arch/arm64/kernel/entry-common.c:772
   el0t_32_sync_handler+0x90/0x140 arch/arm64/kernel/entry-common.c:782
   el0t_32_sync+0x190/0x194 arch/arm64/kernel/entry.S:586
  irq event stamp: 232
  hardirqs last  enabled at (231): [<ffff8000081edf70>] raw_spin_rq_unlock_irq kernel/sched/sched.h:1367 [inline]
  hardirqs last  enabled at (231): [<ffff8000081edf70>] finish_lock_switch kernel/sched/core.c:4943 [inline]
  hardirqs last  enabled at (231): [<ffff8000081edf70>] finish_task_switch.isra.0+0x200/0x880 kernel/sched/core.c:5061
  hardirqs last disabled at (232): [<ffff80000c888bb4>] el1_dbg+0x24/0x80 arch/arm64/kernel/entry-common.c:404
  softirqs last  enabled at (228): [<ffff800008010938>] _stext+0x938/0xf58
  softirqs last disabled at (207): [<ffff800008019380>] ____do_softirq+0x10/0x20 arch/arm64/kernel/irq.c:79
  ---[ end trace 0000000000000000 ]---

The lockdep warning in kernfs_active() is there to ensure that the activated
state stays stable for the caller. For kernfs_find_and_get_node_by_id(), all
that's needed is ensuring that a node which has never been activated can't
be looked up and guaranteeing lookup success when the caller knows the node
to be active, both of which can be achieved by testing the active count
without holding the kernfs_rwsem.

Fix the spurious warning by introducing __kernfs_active() which doesn't have
the lockdep annotation.

Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: syzbot+590ce62b128e79cf0a35@syzkaller.appspotmail.com
Fixes: c25491747b ("kernfs: Add KERNFS_REMOVING flags")
Cc: Amir Goldstein <amir73il@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Link: https://lore.kernel.org/r/Y0SwqBsZ9BMmZv6x@slm.duckdns.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-11-10 19:03:42 +01:00
Ian Kent
92b57842f4 kernfs: dont take i_lock on revalidate
In kernfs_dop_revalidate() when the passed in dentry is negative the
dentry directory is checked to see if it has changed and if so the
negative dentry is discarded so it can refreshed. During this check
the dentry inode i_lock is taken to mitigate against a possible
concurrent rename.

But if it's racing with a rename, becuase the dentry is negative, it
can't be the source it must be the target and it must be going to do
a d_move() otherwise the rename will return an error.

In this case the parent dentry of the target will not change, it will
be the same over the d_move(), only the source dentry parent may change
so the inode i_lock isn't needed.

Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Ian Kent <raven@themaw.net>
Link: https://lore.kernel.org/r/166606036967.13363.9336408133975631967.stgit@donald.themaw.net
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-10-20 13:54:31 +02:00
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