linux-toradex.git/fs/locks.c, branch v6.1-rc1

locks: Fix dropped call to ->fl_release_private()

2022-08-17T19:08:58+00:00

Prior to commit 4149be7bda7e, sys_flock() would allocate the file_lock
struct it was going to use to pass parameters, call ->flock() and then call
locks_free_lock() to get rid of it - which had the side effect of calling
locks_release_private() and thus ->fl_release_private().

With commit 4149be7bda7e, however, this is no longer the case: the struct
is now allocated on the stack, and locks_free_lock() is no longer called -
and thus any remaining private data doesn't get cleaned up either.

This causes afs flock to cause oops.  Kasan catches this as a UAF by the
list_del_init() in afs_fl_release_private() for the file_lock record
produced by afs_fl_copy_lock() as the original record didn't get delisted.
It can be reproduced using the generic/504 xfstest.

Fix this by reinstating the locks_release_private() call in sys_flock().
I'm not sure if this would affect any other filesystems.  If not, then the
release could be done in afs_flock() instead.

Changes
=======
ver #2)
 - Don't need to call ->fl_release_private() after calling the security
   hook, only after calling ->flock().

Fixes: 4149be7bda7e ("fs/lock: Don't allocate file_lock in flock_make_lock().")
cc: Chuck Lever 
cc: Jeff Layton 
cc: Marc Dionne 
cc: linux-afs@lists.infradead.org
cc: linux-fsdevel@vger.kernel.org
Link: https://lore.kernel.org/r/166075758809.3532462.13307935588777587536.stgit@warthog.procyon.org.uk/ # v1
Acked-by: Kuniyuki Iwashima 
Signed-off-by: David Howells 
Signed-off-by: Jeff Layton

fs/lock: Rearrange ops in flock syscall.

2022-07-18T14:01:47+00:00

The previous patch added flock_translate_cmd() in flock syscall.
The test and the other one for LOCK_MAND do not depend on struct
fd and are cheaper, so we can put them at the top and defer
fdget() after that.

Also, we can remove the unlock variable and use type instead.
While at it, we fix this checkpatch error.

  CHECK: spaces preferred around that '|' (ctx:VxV)
  #45: FILE: fs/locks.c:2099:
  +	if (type != F_UNLCK && !(f.file->f_mode & (FMODE_READ|FMODE_WRITE)))
   	                                                     ^

Finally, we can move the can_sleep part just before we use it.

Signed-off-by: Kuniyuki Iwashima 
Signed-off-by: Jeff Layton

fs/lock: Don't allocate file_lock in flock_make_lock().

2022-07-18T14:01:41+00:00

Two functions, flock syscall and locks_remove_flock(), call
flock_make_lock().  It allocates struct file_lock from slab
cache if its argument fl is NULL.

When we call flock syscall, we pass NULL to allocate memory
for struct file_lock.  However, we always free it at the end
by locks_free_lock().  We need not allocate it and instead
should use a local variable as locks_remove_flock() does.

Also, the validation for flock_translate_cmd() is not necessary
for locks_remove_flock().  So we move the part to flock syscall
and make flock_make_lock() return nothing.

Signed-off-by: Kuniyuki Iwashima 
Reviewed-by: Chuck Lever 
Signed-off-by: Jeff Layton

fs/lock: add 2 callbacks to lock_manager_operations to resolve conflict

2022-05-19T16:25:39+00:00

Add 2 new callbacks, lm_lock_expirable and lm_expire_lock, to
lock_manager_operations to allow the lock manager to take appropriate
action to resolve the lock conflict if possible.

A new field, lm_mod_owner, is also added to lock_manager_operations.
The lm_mod_owner is used by the fs/lock code to make sure the lock
manager module such as nfsd, is not freed while lock conflict is being
resolved.

lm_lock_expirable checks and returns true to indicate that the lock
conflict can be resolved else return false. This callback must be
called with the flc_lock held so it can not block.

lm_expire_lock is called to resolve the lock conflict if the returned
value from lm_lock_expirable is true. This callback is called without
the flc_lock held since it's allowed to block. Upon returning from
this callback, the lock conflict should be resolved and the caller is
expected to restart the conflict check from the beginnning of the list.

Lock manager, such as NFSv4 courteous server, uses this callback to
resolve conflict by destroying lock owner, or the NFSv4 courtesy client
(client that has expired but allowed to maintains its states) that owns
the lock.

Reviewed-by: J. Bruce Fields 
Signed-off-by: Dai Ngo 
Signed-off-by: Chuck Lever 
Reviewed-by: Jeff Layton

fs/lock: add helper locks_owner_has_blockers to check for blockers

2022-05-19T16:25:39+00:00

Add helper locks_owner_has_blockers to check if there is any blockers
for a given lockowner.

Reviewed-by: J. Bruce Fields 
Signed-off-by: Dai Ngo 
Signed-off-by: Chuck Lever 
Reviewed-by: Jeff Layton

fs: move locking sysctls where they are used

2022-01-22T06:33:36+00:00

kernel/sysctl.c is a kitchen sink where everyone leaves their dirty
dishes, this makes it very difficult to maintain.

To help with this maintenance let's start by moving sysctls to places
where they actually belong.  The proc sysctl maintainers do not want to
know what sysctl knobs you wish to add for your own piece of code, we
just care about the core logic.

The locking fs sysctls are only used on fs/locks.c, so move them there.

Link: https://lkml.kernel.org/r/20211129205548.605569-7-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain 
Cc: Al Viro 
Cc: Andy Shevchenko 
Cc: Antti Palosaari 
Cc: Eric Biederman 
Cc: Iurii Zaikin 
Cc: "J. Bruce Fields" 
Cc: Jeff Layton 
Cc: Kees Cook 
Cc: Lukas Middendorf 
Cc: Stephen Kitt 
Cc: Xiaoming Ni 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

locks: remove changelog comments

2021-10-19T18:11:39+00:00

This is only of historical interest, and anyone interested in the
history can dig out an old version of locks.c from from git.

Triggered by the observation that it references the now-removed
Documentation/filesystems/mandatory-locking.rst.

Reported-by: Mauro Carvalho Chehab 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Jeff Layton

locks: remove LOCK_MAND flock lock support

2021-09-10T20:21:44+00:00

As best I can tell, the logic for these has been broken for a long time
(at least before the move to git), such that they never conflict with
anything. Also, nothing checks for these flags and prevented opens or
read/write behavior on the files. They don't seem to do anything.

Given that, we can rip these symbols out of the kernel, and just make
flock(2) return 0 when LOCK_MAND is set in order to preserve existing
behavior.

Cc: Matthew Wilcox 
Cc: Stephen Rothwell 
Signed-off-by: Jeff Layton

Revert "memcg: enable accounting for file lock caches"

2021-09-07T18:21:48+00:00

This reverts commit 0f12156dff2862ac54235fc72703f18770769042.

The kernel test robot reports a sizeable performance regression for this
commit, and while it clearly does the rigth thing in theory, we'll need
to look at just how to avoid or minimize the performance overhead of the
memcg accounting.

People already have suggestions on how to do that, but it's "future
work".

So revert it for now.

Link: https://lore.kernel.org/lkml/20210907150757.GE17617@xsang-OptiPlex-9020/
Acked-by: Jens Axboe 
Acked-by: Shakeel Butt 
Acked-by: Roman Gushchin 
Cc: Tejun Heo 
Signed-off-by: Linus Torvalds

Merge branch 'akpm' (patches from Andrew)

2021-09-03T17:08:28+00:00

Merge misc updates from Andrew Morton:
 "173 patches.

  Subsystems affected by this series: ia64, ocfs2, block, and mm (debug,
  pagecache, gup, swap, shmem, memcg, selftests, pagemap, mremap,
  bootmem, sparsemem, vmalloc, kasan, pagealloc, memory-failure,
  hugetlb, userfaultfd, vmscan, compaction, mempolicy, memblock,
  oom-kill, migration, ksm, percpu, vmstat, and madvise)"

* emailed patches from Andrew Morton : (173 commits)
  mm/madvise: add MADV_WILLNEED to process_madvise()
  mm/vmstat: remove unneeded return value
  mm/vmstat: simplify the array size calculation
  mm/vmstat: correct some wrong comments
  mm/percpu,c: remove obsolete comments of pcpu_chunk_populated()
  selftests: vm: add COW time test for KSM pages
  selftests: vm: add KSM merging time test
  mm: KSM: fix data type
  selftests: vm: add KSM merging across nodes test
  selftests: vm: add KSM zero page merging test
  selftests: vm: add KSM unmerge test
  selftests: vm: add KSM merge test
  mm/migrate: correct kernel-doc notation
  mm: wire up syscall process_mrelease
  mm: introduce process_mrelease system call
  memblock: make memblock_find_in_range method private
  mm/mempolicy.c: use in_task() in mempolicy_slab_node()
  mm/mempolicy: unify the create() func for bind/interleave/prefer-many policies
  mm/mempolicy: advertise new MPOL_PREFERRED_MANY
  mm/hugetlb: add support for mempolicy MPOL_PREFERRED_MANY
  ...