Commit Graph

267 Commits

Author SHA1 Message Date
David Howells
51d37982bb
cachefiles: Set the max subreq size for cache writes to MAX_RW_COUNT
Set the maximum size of a subrequest that writes to cachefiles to be
MAX_RW_COUNT so that we don't overrun the maximum write we can make to the
backing filesystem.

Signed-off-by: David Howells <dhowells@redhat.com>
Link: https://lore.kernel.org/r/1599005.1721398742@warthog.procyon.org.uk
cc: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-24 10:53:13 +02:00
Christian Brauner
eeb17984e8
Merge patch series "cachefiles: random bugfixes"
libaokun@huaweicloud.com <libaokun@huaweicloud.com> says:

This is the third version of this patch series, in which another patch set
is subsumed into this one to avoid confusing the two patch sets.
(https://patchwork.kernel.org/project/linux-fsdevel/list/?series=854914)

We've been testing ondemand mode for cachefiles since January, and we're
almost done. We hit a lot of issues during the testing period, and this
patch series fixes some of the issues. The patches have passed internal
testing without regression.

The following is a brief overview of the patches, see the patches for
more details.

Patch 1-2: Add fscache_try_get_volume() helper function to avoid
fscache_volume use-after-free on cache withdrawal.

Patch 3: Fix cachefiles_lookup_cookie() and cachefiles_withdraw_cache()
concurrency causing cachefiles_volume use-after-free.

Patch 4: Propagate error codes returned by vfs_getxattr() to avoid
endless loops.

Patch 5-7: A read request waiting for reopen could be closed maliciously
before the reopen worker is executing or waiting to be scheduled. So
ondemand_object_worker() may be called after the info and object and even
the cache have been freed and trigger use-after-free. So use
cancel_work_sync() in cachefiles_ondemand_clean_object() to cancel the
reopen worker or wait for it to finish. Since it makes no sense to wait
for the daemon to complete the reopen request, to avoid this pointless
operation blocking cancel_work_sync(), Patch 1 avoids request generation
by the DROPPING state when the request has not been sent, and Patch 2
flushes the requests of the current object before cancel_work_sync().

Patch 8: Cyclic allocation of msg_id to avoid msg_id reuse misleading
the daemon to cause hung.

Patch 9: Hold xas_lock during polling to avoid dereferencing reqs causing
use-after-free. This issue was triggered frequently in our tests, and we
found that anolis 5.10 had fixed it. So to avoid failing the test, this
patch is pushed upstream as well.

Baokun Li (7):
  netfs, fscache: export fscache_put_volume() and add
    fscache_try_get_volume()
  cachefiles: fix slab-use-after-free in fscache_withdraw_volume()
  cachefiles: fix slab-use-after-free in cachefiles_withdraw_cookie()
  cachefiles: propagate errors from vfs_getxattr() to avoid infinite
    loop
  cachefiles: stop sending new request when dropping object
  cachefiles: cancel all requests for the object that is being dropped
  cachefiles: cyclic allocation of msg_id to avoid reuse

Hou Tao (1):
  cachefiles: wait for ondemand_object_worker to finish when dropping
    object

Jingbo Xu (1):
  cachefiles: add missing lock protection when polling

 fs/cachefiles/cache.c          | 45 ++++++++++++++++++++++++++++-
 fs/cachefiles/daemon.c         |  4 +--
 fs/cachefiles/internal.h       |  3 ++
 fs/cachefiles/ondemand.c       | 52 ++++++++++++++++++++++++++++++----
 fs/cachefiles/volume.c         |  1 -
 fs/cachefiles/xattr.c          |  5 +++-
 fs/netfs/fscache_volume.c      | 14 +++++++++
 fs/netfs/internal.h            |  2 --
 include/linux/fscache-cache.h  |  6 ++++
 include/trace/events/fscache.h |  4 +++
 10 files changed, 123 insertions(+), 13 deletions(-)

Link: https://lore.kernel.org/r/20240628062930.2467993-1-libaokun@huaweicloud.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-05 18:40:40 +02:00
Jingbo Xu
cf5bb09e74 cachefiles: add missing lock protection when polling
Add missing lock protection in poll routine when iterating xarray,
otherwise:

Even with RCU read lock held, only the slot of the radix tree is
ensured to be pinned there, while the data structure (e.g. struct
cachefiles_req) stored in the slot has no such guarantee.  The poll
routine will iterate the radix tree and dereference cachefiles_req
accordingly.  Thus RCU read lock is not adequate in this case and
spinlock is needed here.

Fixes: b817e22b2e ("cachefiles: narrow the scope of triggering EPOLLIN events in ondemand mode")
Signed-off-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240628062930.2467993-10-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-03 10:36:16 +02:00
Baokun Li
19f4f39909 cachefiles: cyclic allocation of msg_id to avoid reuse
Reusing the msg_id after a maliciously completed reopen request may cause
a read request to remain unprocessed and result in a hung, as shown below:

       t1       |      t2       |      t3
-------------------------------------------------
cachefiles_ondemand_select_req
 cachefiles_ondemand_object_is_close(A)
 cachefiles_ondemand_set_object_reopening(A)
 queue_work(fscache_object_wq, &info->work)
                ondemand_object_worker
                 cachefiles_ondemand_init_object(A)
                  cachefiles_ondemand_send_req(OPEN)
                    // get msg_id 6
                    wait_for_completion(&req_A->done)
cachefiles_ondemand_daemon_read
 // read msg_id 6 req_A
 cachefiles_ondemand_get_fd
 copy_to_user
                                // Malicious completion msg_id 6
                                copen 6,-1
                                cachefiles_ondemand_copen
                                 complete(&req_A->done)
                                 // will not set the object to close
                                 // because ondemand_id && fd is valid.

                // ondemand_object_worker() is done
                // but the object is still reopening.

                                // new open req_B
                                cachefiles_ondemand_init_object(B)
                                 cachefiles_ondemand_send_req(OPEN)
                                 // reuse msg_id 6
process_open_req
 copen 6,A.size
 // The expected failed copen was executed successfully

Expect copen to fail, and when it does, it closes fd, which sets the
object to close, and then close triggers reopen again. However, due to
msg_id reuse resulting in a successful copen, the anonymous fd is not
closed until the daemon exits. Therefore read requests waiting for reopen
to complete may trigger hung task.

To avoid this issue, allocate the msg_id cyclically to avoid reusing the
msg_id for a very short duration of time.

Fixes: c838305450 ("cachefiles: notify the user daemon when looking up cookie")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240628062930.2467993-9-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-03 10:36:16 +02:00
Hou Tao
12e009d608 cachefiles: wait for ondemand_object_worker to finish when dropping object
When queuing ondemand_object_worker() to re-open the object,
cachefiles_object is not pinned. The cachefiles_object may be freed when
the pending read request is completed intentionally and the related
erofs is umounted. If ondemand_object_worker() runs after the object is
freed, it will incur use-after-free problem as shown below.

process A  processs B  process C  process D

cachefiles_ondemand_send_req()
// send a read req X
// wait for its completion

           // close ondemand fd
           cachefiles_ondemand_fd_release()
           // set object as CLOSE

                       cachefiles_ondemand_daemon_read()
                       // set object as REOPENING
                       queue_work(fscache_wq, &info->ondemand_work)

                                // close /dev/cachefiles
                                cachefiles_daemon_release
                                cachefiles_flush_reqs
                                complete(&req->done)

// read req X is completed
// umount the erofs fs
cachefiles_put_object()
// object will be freed
cachefiles_ondemand_deinit_obj_info()
kmem_cache_free(object)
                       // both info and object are freed
                       ondemand_object_worker()

When dropping an object, it is no longer necessary to reopen the object,
so use cancel_work_sync() to cancel or wait for ondemand_object_worker()
to finish.

Fixes: 0a7e54c195 ("cachefiles: resend an open request if the read request's object is closed")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240628062930.2467993-8-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-03 10:36:16 +02:00
Baokun Li
751f524635 cachefiles: cancel all requests for the object that is being dropped
Because after an object is dropped, requests for that object are useless,
cancel them to avoid causing other problems.

This prepares for the later addition of cancel_work_sync(). After the
reopen requests is generated, cancel it to avoid cancel_work_sync()
blocking by waiting for daemon to complete the reopen requests.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240628062930.2467993-7-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-03 10:36:15 +02:00
Baokun Li
b2415d1f45 cachefiles: stop sending new request when dropping object
Added CACHEFILES_ONDEMAND_OBJSTATE_DROPPING indicates that the cachefiles
object is being dropped, and is set after the close request for the dropped
object completes, and no new requests are allowed to be sent after this
state.

This prepares for the later addition of cancel_work_sync(). It prevents
leftover reopen requests from being sent, to avoid processing unnecessary
requests and to avoid cancel_work_sync() blocking by waiting for daemon to
complete the reopen requests.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240628062930.2467993-6-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-03 10:36:15 +02:00
Baokun Li
0ece614a52 cachefiles: propagate errors from vfs_getxattr() to avoid infinite loop
In cachefiles_check_volume_xattr(), the error returned by vfs_getxattr()
is not passed to ret, so it ends up returning -ESTALE, which leads to an
endless loop as follows:

cachefiles_acquire_volume
retry:
  ret = cachefiles_check_volume_xattr
    ret = -ESTALE
    xlen = vfs_getxattr // return -EIO
    // The ret is not updated when xlen < 0, so -ESTALE is returned.
    return ret
  // Supposed to jump out of the loop at this judgement.
  if (ret != -ESTALE)
      goto error_dir;
  cachefiles_bury_object
    //  EIO causes rename failure
  goto retry;

Hence propagate the error returned by vfs_getxattr() to avoid the above
issue. Do the same in cachefiles_check_auxdata().

Fixes: 32e150037d ("fscache, cachefiles: Store the volume coherency data")
Fixes: 72b957856b ("cachefiles: Implement metadata/coherency data storage in xattrs")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240628062930.2467993-5-libaokun@huaweicloud.com
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-03 10:36:15 +02:00
Baokun Li
5d8f805789 cachefiles: fix slab-use-after-free in cachefiles_withdraw_cookie()
We got the following issue in our fault injection stress test:

==================================================================
BUG: KASAN: slab-use-after-free in cachefiles_withdraw_cookie+0x4d9/0x600
Read of size 8 at addr ffff888118efc000 by task kworker/u78:0/109

CPU: 13 PID: 109 Comm: kworker/u78:0 Not tainted 6.8.0-dirty #566
Call Trace:
 <TASK>
 kasan_report+0x93/0xc0
 cachefiles_withdraw_cookie+0x4d9/0x600
 fscache_cookie_state_machine+0x5c8/0x1230
 fscache_cookie_worker+0x91/0x1c0
 process_one_work+0x7fa/0x1800
 [...]

Allocated by task 117:
 kmalloc_trace+0x1b3/0x3c0
 cachefiles_acquire_volume+0xf3/0x9c0
 fscache_create_volume_work+0x97/0x150
 process_one_work+0x7fa/0x1800
 [...]

Freed by task 120301:
 kfree+0xf1/0x2c0
 cachefiles_withdraw_cache+0x3fa/0x920
 cachefiles_put_unbind_pincount+0x1f6/0x250
 cachefiles_daemon_release+0x13b/0x290
 __fput+0x204/0xa00
 task_work_run+0x139/0x230
 do_exit+0x87a/0x29b0
 [...]
==================================================================

Following is the process that triggers the issue:

           p1                |             p2
------------------------------------------------------------
                              fscache_begin_lookup
                               fscache_begin_volume_access
                                fscache_cache_is_live(fscache_cache)
cachefiles_daemon_release
 cachefiles_put_unbind_pincount
  cachefiles_daemon_unbind
   cachefiles_withdraw_cache
    fscache_withdraw_cache
     fscache_set_cache_state(cache, FSCACHE_CACHE_IS_WITHDRAWN);
    cachefiles_withdraw_objects(cache)
    fscache_wait_for_objects(fscache)
      atomic_read(&fscache_cache->object_count) == 0
                              fscache_perform_lookup
                               cachefiles_lookup_cookie
                                cachefiles_alloc_object
                                 refcount_set(&object->ref, 1);
                                 object->volume = volume
                                 fscache_count_object(vcookie->cache);
                                  atomic_inc(&fscache_cache->object_count)
    cachefiles_withdraw_volumes
     cachefiles_withdraw_volume
      fscache_withdraw_volume
      __cachefiles_free_volume
       kfree(cachefiles_volume)
                              fscache_cookie_state_machine
                               cachefiles_withdraw_cookie
                                cache = object->volume->cache;
                                // cachefiles_volume UAF !!!

After setting FSCACHE_CACHE_IS_WITHDRAWN, wait for all the cookie lookups
to complete first, and then wait for fscache_cache->object_count == 0 to
avoid the cookie exiting after the volume has been freed and triggering
the above issue. Therefore call fscache_withdraw_volume() before calling
cachefiles_withdraw_objects().

This way, after setting FSCACHE_CACHE_IS_WITHDRAWN, only the following two
cases will occur:
1) fscache_begin_lookup fails in fscache_begin_volume_access().
2) fscache_withdraw_volume() will ensure that fscache_count_object() has
   been executed before calling fscache_wait_for_objects().

Fixes: fe2140e2f5 ("cachefiles: Implement volume support")
Suggested-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240628062930.2467993-4-libaokun@huaweicloud.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-03 10:36:15 +02:00
Baokun Li
522018a0de cachefiles: fix slab-use-after-free in fscache_withdraw_volume()
We got the following issue in our fault injection stress test:

==================================================================
BUG: KASAN: slab-use-after-free in fscache_withdraw_volume+0x2e1/0x370
Read of size 4 at addr ffff88810680be08 by task ondemand-04-dae/5798

CPU: 0 PID: 5798 Comm: ondemand-04-dae Not tainted 6.8.0-dirty #565
Call Trace:
 kasan_check_range+0xf6/0x1b0
 fscache_withdraw_volume+0x2e1/0x370
 cachefiles_withdraw_volume+0x31/0x50
 cachefiles_withdraw_cache+0x3ad/0x900
 cachefiles_put_unbind_pincount+0x1f6/0x250
 cachefiles_daemon_release+0x13b/0x290
 __fput+0x204/0xa00
 task_work_run+0x139/0x230

Allocated by task 5820:
 __kmalloc+0x1df/0x4b0
 fscache_alloc_volume+0x70/0x600
 __fscache_acquire_volume+0x1c/0x610
 erofs_fscache_register_volume+0x96/0x1a0
 erofs_fscache_register_fs+0x49a/0x690
 erofs_fc_fill_super+0x6c0/0xcc0
 vfs_get_super+0xa9/0x140
 vfs_get_tree+0x8e/0x300
 do_new_mount+0x28c/0x580
 [...]

Freed by task 5820:
 kfree+0xf1/0x2c0
 fscache_put_volume.part.0+0x5cb/0x9e0
 erofs_fscache_unregister_fs+0x157/0x1b0
 erofs_kill_sb+0xd9/0x1c0
 deactivate_locked_super+0xa3/0x100
 vfs_get_super+0x105/0x140
 vfs_get_tree+0x8e/0x300
 do_new_mount+0x28c/0x580
 [...]
==================================================================

Following is the process that triggers the issue:

        mount failed         |         daemon exit
------------------------------------------------------------
 deactivate_locked_super        cachefiles_daemon_release
  erofs_kill_sb
   erofs_fscache_unregister_fs
    fscache_relinquish_volume
     __fscache_relinquish_volume
      fscache_put_volume(fscache_volume, fscache_volume_put_relinquish)
       zero = __refcount_dec_and_test(&fscache_volume->ref, &ref);
                                 cachefiles_put_unbind_pincount
                                  cachefiles_daemon_unbind
                                   cachefiles_withdraw_cache
                                    cachefiles_withdraw_volumes
                                     list_del_init(&volume->cache_link)
       fscache_free_volume(fscache_volume)
        cache->ops->free_volume
         cachefiles_free_volume
          list_del_init(&cachefiles_volume->cache_link);
        kfree(fscache_volume)
                                     cachefiles_withdraw_volume
                                      fscache_withdraw_volume
                                       fscache_volume->n_accesses
                                       // fscache_volume UAF !!!

The fscache_volume in cache->volumes must not have been freed yet, but its
reference count may be 0. So use the new fscache_try_get_volume() helper
function try to get its reference count.

If the reference count of fscache_volume is 0, fscache_put_volume() is
freeing it, so wait for it to be removed from cache->volumes.

If its reference count is not 0, call cachefiles_withdraw_volume() with
reference count protection to avoid the above issue.

Fixes: fe2140e2f5 ("cachefiles: Implement volume support")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240628062930.2467993-3-libaokun@huaweicloud.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-03 10:36:14 +02:00
Gao Xiang
3d117494e2 cachefiles: remove unneeded include of <linux/fdtable.h>
close_fd() has been killed, let's get rid of unneeded
<linux/fdtable.h> as Al Viro pointed out [1].

[1] https://lore.kernel.org/r/20240603034055.GI1629371@ZenIV

Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Link: https://lore.kernel.org/r/20240603062344.818290-1-hsiangkao@linux.alibaba.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-03 15:39:17 +02:00
Christian Brauner
a82c13d299
Merge patch series "cachefiles: some bugfixes and cleanups for ondemand requests"
libaokun@huaweicloud.com <libaokun@huaweicloud.com> says:

We've been testing ondemand mode for cachefiles since January, and we're
almost done. We hit a lot of issues during the testing period, and this
patch set fixes some of the issues related to ondemand requests.
The patches have passed internal testing without regression.

The following is a brief overview of the patches, see the patches for
more details.

Patch 1-5: Holding reference counts of reqs and objects on read requests
to avoid malicious restore leading to use-after-free.

Patch 6-10: Add some consistency checks to copen/cread/get_fd to avoid
malicious copen/cread/close fd injections causing use-after-free or hung.

Patch 11: When cache is marked as CACHEFILES_DEAD, flush all requests,
otherwise the kernel may be hung. since this state is irreversible, the
daemon can read open requests but cannot copen.

Patch 12: Allow interrupting a read request being processed by killing
the read process as a way of avoiding hung in some special cases.

 fs/cachefiles/daemon.c            |   3 +-
 fs/cachefiles/internal.h          |   5 +
 fs/cachefiles/ondemand.c          | 217 ++++++++++++++++++++++--------
 include/trace/events/cachefiles.h |   8 +-
 4 files changed, 176 insertions(+), 57 deletions(-)

* patches from https://lore.kernel.org/r/20240522114308.2402121-1-libaokun@huaweicloud.com:
  cachefiles: make on-demand read killable
  cachefiles: flush all requests after setting CACHEFILES_DEAD
  cachefiles: Set object to close if ondemand_id < 0 in copen
  cachefiles: defer exposing anon_fd until after copy_to_user() succeeds
  cachefiles: never get a new anonymous fd if ondemand_id is valid
  cachefiles: add spin_lock for cachefiles_ondemand_info
  cachefiles: add consistency check for copen/cread
  cachefiles: remove err_put_fd label in cachefiles_ondemand_daemon_read()
  cachefiles: fix slab-use-after-free in cachefiles_ondemand_daemon_read()
  cachefiles: fix slab-use-after-free in cachefiles_ondemand_get_fd()
  cachefiles: remove requests from xarray during flushing requests
  cachefiles: add output string to cachefiles_obj_[get|put]_ondemand_fd

Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:40 +02:00
Baokun Li
bc9dde6155
cachefiles: make on-demand read killable
Replacing wait_for_completion() with wait_for_completion_killable() in
cachefiles_ondemand_send_req() allows us to kill processes that might
trigger a hunk_task if the daemon is abnormal.

But now only CACHEFILES_OP_READ is killable, because OP_CLOSE and OP_OPEN
is initiated from kworker context and the signal is prohibited in these
kworker.

Note that when the req in xas changes, i.e. xas_load(&xas) != req, it
means that a process will complete the current request soon, so wait
again for the request to be completed.

In addition, add the cachefiles_ondemand_finish_req() helper function to
simplify the code.

Suggested-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-13-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:31 +02:00
Baokun Li
85e833cd72
cachefiles: flush all requests after setting CACHEFILES_DEAD
In ondemand mode, when the daemon is processing an open request, if the
kernel flags the cache as CACHEFILES_DEAD, the cachefiles_daemon_write()
will always return -EIO, so the daemon can't pass the copen to the kernel.
Then the kernel process that is waiting for the copen triggers a hung_task.

Since the DEAD state is irreversible, it can only be exited by closing
/dev/cachefiles. Therefore, after calling cachefiles_io_error() to mark
the cache as CACHEFILES_DEAD, if in ondemand mode, flush all requests to
avoid the above hungtask. We may still be able to read some of the cached
data before closing the fd of /dev/cachefiles.

Note that this relies on the patch that adds reference counting to the req,
otherwise it may UAF.

Fixes: c838305450 ("cachefiles: notify the user daemon when looking up cookie")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-12-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:31 +02:00
Zizhi Wo
4f8703fb34
cachefiles: Set object to close if ondemand_id < 0 in copen
If copen is maliciously called in the user mode, it may delete the request
corresponding to the random id. And the request may have not been read yet.

Note that when the object is set to reopen, the open request will be done
with the still reopen state in above case. As a result, the request
corresponding to this object is always skipped in select_req function, so
the read request is never completed and blocks other process.

Fix this issue by simply set object to close if its id < 0 in copen.

Signed-off-by: Zizhi Wo <wozizhi@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-11-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:30 +02:00
Baokun Li
4b4391e77a
cachefiles: defer exposing anon_fd until after copy_to_user() succeeds
After installing the anonymous fd, we can now see it in userland and close
it. However, at this point we may not have gotten the reference count of
the cache, but we will put it during colse fd, so this may cause a cache
UAF.

So grab the cache reference count before fd_install(). In addition, by
kernel convention, fd is taken over by the user land after fd_install(),
and the kernel should not call close_fd() after that, i.e., it should call
fd_install() after everything is ready, thus fd_install() is called after
copy_to_user() succeeds.

Fixes: c838305450 ("cachefiles: notify the user daemon when looking up cookie")
Suggested-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-10-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:30 +02:00
Baokun Li
4988e35e95
cachefiles: never get a new anonymous fd if ondemand_id is valid
Now every time the daemon reads an open request, it gets a new anonymous fd
and ondemand_id. With the introduction of "restore", it is possible to read
the same open request more than once, and therefore an object can have more
than one anonymous fd.

If the anonymous fd is not unique, the following concurrencies will result
in an fd leak:

     t1     |         t2         |          t3
------------------------------------------------------------
 cachefiles_ondemand_init_object
  cachefiles_ondemand_send_req
   REQ_A = kzalloc(sizeof(*req) + data_len)
   wait_for_completion(&REQ_A->done)
            cachefiles_daemon_read
             cachefiles_ondemand_daemon_read
              REQ_A = cachefiles_ondemand_select_req
              cachefiles_ondemand_get_fd
                load->fd = fd0
                ondemand_id = object_id0
                                  ------ restore ------
                                  cachefiles_ondemand_restore
                                   // restore REQ_A
                                  cachefiles_daemon_read
                                   cachefiles_ondemand_daemon_read
                                    REQ_A = cachefiles_ondemand_select_req
                                      cachefiles_ondemand_get_fd
                                        load->fd = fd1
                                        ondemand_id = object_id1
             process_open_req(REQ_A)
             write(devfd, ("copen %u,%llu", msg->msg_id, size))
             cachefiles_ondemand_copen
              xa_erase(&cache->reqs, id)
              complete(&REQ_A->done)
   kfree(REQ_A)
                                  process_open_req(REQ_A)
                                  // copen fails due to no req
                                  // daemon close(fd1)
                                  cachefiles_ondemand_fd_release
                                   // set object closed
 -- umount --
 cachefiles_withdraw_cookie
  cachefiles_ondemand_clean_object
   cachefiles_ondemand_init_close_req
    if (!cachefiles_ondemand_object_is_open(object))
      return -ENOENT;
    // The fd0 is not closed until the daemon exits.

However, the anonymous fd holds the reference count of the object and the
object holds the reference count of the cookie. So even though the cookie
has been relinquished, it will not be unhashed and freed until the daemon
exits.

In fscache_hash_cookie(), when the same cookie is found in the hash list,
if the cookie is set with the FSCACHE_COOKIE_RELINQUISHED bit, then the new
cookie waits for the old cookie to be unhashed, while the old cookie is
waiting for the leaked fd to be closed, if the daemon does not exit in time
it will trigger a hung task.

To avoid this, allocate a new anonymous fd only if no anonymous fd has
been allocated (ondemand_id == 0) or if the previously allocated anonymous
fd has been closed (ondemand_id == -1). Moreover, returns an error if
ondemand_id is valid, letting the daemon know that the current userland
restore logic is abnormal and needs to be checked.

Fixes: c838305450 ("cachefiles: notify the user daemon when looking up cookie")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-9-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:30 +02:00
Baokun Li
0a79004083
cachefiles: add spin_lock for cachefiles_ondemand_info
The following concurrency may cause a read request to fail to be completed
and result in a hung:

           t1             |             t2
---------------------------------------------------------
                            cachefiles_ondemand_copen
                              req = xa_erase(&cache->reqs, id)
// Anon fd is maliciously closed.
cachefiles_ondemand_fd_release
  xa_lock(&cache->reqs)
  cachefiles_ondemand_set_object_close(object)
  xa_unlock(&cache->reqs)
                              cachefiles_ondemand_set_object_open
                              // No one will ever close it again.
cachefiles_ondemand_daemon_read
  cachefiles_ondemand_select_req
  // Get a read req but its fd is already closed.
  // The daemon can't issue a cread ioctl with an closed fd, then hung.

So add spin_lock for cachefiles_ondemand_info to protect ondemand_id and
state, thus we can avoid the above problem in cachefiles_ondemand_copen()
by using ondemand_id to determine if fd has been closed.

Fixes: c838305450 ("cachefiles: notify the user daemon when looking up cookie")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-8-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:30 +02:00
Baokun Li
a26dc49df3
cachefiles: add consistency check for copen/cread
This prevents malicious processes from completing random copen/cread
requests and crashing the system. Added checks are listed below:

  * Generic, copen can only complete open requests, and cread can only
    complete read requests.
  * For copen, ondemand_id must not be 0, because this indicates that the
    request has not been read by the daemon.
  * For cread, the object corresponding to fd and req should be the same.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-7-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:30 +02:00
Baokun Li
3e6d704f02
cachefiles: remove err_put_fd label in cachefiles_ondemand_daemon_read()
The err_put_fd label is only used once, so remove it to make the code
more readable. In addition, the logic for deleting error request and
CLOSE request is merged to simplify the code.

Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-6-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:29 +02:00
Baokun Li
da4a827416
cachefiles: fix slab-use-after-free in cachefiles_ondemand_daemon_read()
We got the following issue in a fuzz test of randomly issuing the restore
command:

==================================================================
BUG: KASAN: slab-use-after-free in cachefiles_ondemand_daemon_read+0xb41/0xb60
Read of size 8 at addr ffff888122e84088 by task ondemand-04-dae/963

CPU: 13 PID: 963 Comm: ondemand-04-dae Not tainted 6.8.0-dirty #564
Call Trace:
 kasan_report+0x93/0xc0
 cachefiles_ondemand_daemon_read+0xb41/0xb60
 vfs_read+0x169/0xb50
 ksys_read+0xf5/0x1e0

Allocated by task 116:
 kmem_cache_alloc+0x140/0x3a0
 cachefiles_lookup_cookie+0x140/0xcd0
 fscache_cookie_state_machine+0x43c/0x1230
 [...]

Freed by task 792:
 kmem_cache_free+0xfe/0x390
 cachefiles_put_object+0x241/0x480
 fscache_cookie_state_machine+0x5c8/0x1230
 [...]
==================================================================

Following is the process that triggers the issue:

     mount  |   daemon_thread1    |    daemon_thread2
------------------------------------------------------------
cachefiles_withdraw_cookie
 cachefiles_ondemand_clean_object(object)
  cachefiles_ondemand_send_req
   REQ_A = kzalloc(sizeof(*req) + data_len)
   wait_for_completion(&REQ_A->done)

            cachefiles_daemon_read
             cachefiles_ondemand_daemon_read
              REQ_A = cachefiles_ondemand_select_req
              msg->object_id = req->object->ondemand->ondemand_id
                                  ------ restore ------
                                  cachefiles_ondemand_restore
                                  xas_for_each(&xas, req, ULONG_MAX)
                                   xas_set_mark(&xas, CACHEFILES_REQ_NEW)

                                  cachefiles_daemon_read
                                   cachefiles_ondemand_daemon_read
                                    REQ_A = cachefiles_ondemand_select_req
              copy_to_user(_buffer, msg, n)
               xa_erase(&cache->reqs, id)
               complete(&REQ_A->done)
              ------ close(fd) ------
              cachefiles_ondemand_fd_release
               cachefiles_put_object
 cachefiles_put_object
  kmem_cache_free(cachefiles_object_jar, object)
                                    REQ_A->object->ondemand->ondemand_id
                                     // object UAF !!!

When we see the request within xa_lock, req->object must not have been
freed yet, so grab the reference count of object before xa_unlock to
avoid the above issue.

Fixes: 0a7e54c195 ("cachefiles: resend an open request if the read request's object is closed")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-5-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:29 +02:00
Baokun Li
de3e26f9e5
cachefiles: fix slab-use-after-free in cachefiles_ondemand_get_fd()
We got the following issue in a fuzz test of randomly issuing the restore
command:

==================================================================
BUG: KASAN: slab-use-after-free in cachefiles_ondemand_daemon_read+0x609/0xab0
Write of size 4 at addr ffff888109164a80 by task ondemand-04-dae/4962

CPU: 11 PID: 4962 Comm: ondemand-04-dae Not tainted 6.8.0-rc7-dirty #542
Call Trace:
 kasan_report+0x94/0xc0
 cachefiles_ondemand_daemon_read+0x609/0xab0
 vfs_read+0x169/0xb50
 ksys_read+0xf5/0x1e0

Allocated by task 626:
 __kmalloc+0x1df/0x4b0
 cachefiles_ondemand_send_req+0x24d/0x690
 cachefiles_create_tmpfile+0x249/0xb30
 cachefiles_create_file+0x6f/0x140
 cachefiles_look_up_object+0x29c/0xa60
 cachefiles_lookup_cookie+0x37d/0xca0
 fscache_cookie_state_machine+0x43c/0x1230
 [...]

Freed by task 626:
 kfree+0xf1/0x2c0
 cachefiles_ondemand_send_req+0x568/0x690
 cachefiles_create_tmpfile+0x249/0xb30
 cachefiles_create_file+0x6f/0x140
 cachefiles_look_up_object+0x29c/0xa60
 cachefiles_lookup_cookie+0x37d/0xca0
 fscache_cookie_state_machine+0x43c/0x1230
 [...]
==================================================================

Following is the process that triggers the issue:

     mount  |   daemon_thread1    |    daemon_thread2
------------------------------------------------------------
 cachefiles_ondemand_init_object
  cachefiles_ondemand_send_req
   REQ_A = kzalloc(sizeof(*req) + data_len)
   wait_for_completion(&REQ_A->done)

            cachefiles_daemon_read
             cachefiles_ondemand_daemon_read
              REQ_A = cachefiles_ondemand_select_req
              cachefiles_ondemand_get_fd
              copy_to_user(_buffer, msg, n)
            process_open_req(REQ_A)
                                  ------ restore ------
                                  cachefiles_ondemand_restore
                                  xas_for_each(&xas, req, ULONG_MAX)
                                   xas_set_mark(&xas, CACHEFILES_REQ_NEW);

                                  cachefiles_daemon_read
                                   cachefiles_ondemand_daemon_read
                                    REQ_A = cachefiles_ondemand_select_req

             write(devfd, ("copen %u,%llu", msg->msg_id, size));
             cachefiles_ondemand_copen
              xa_erase(&cache->reqs, id)
              complete(&REQ_A->done)
   kfree(REQ_A)
                                    cachefiles_ondemand_get_fd(REQ_A)
                                     fd = get_unused_fd_flags
                                     file = anon_inode_getfile
                                     fd_install(fd, file)
                                     load = (void *)REQ_A->msg.data;
                                     load->fd = fd;
                                     // load UAF !!!

This issue is caused by issuing a restore command when the daemon is still
alive, which results in a request being processed multiple times thus
triggering a UAF. So to avoid this problem, add an additional reference
count to cachefiles_req, which is held while waiting and reading, and then
released when the waiting and reading is over.

Note that since there is only one reference count for waiting, we need to
avoid the same request being completed multiple times, so we can only
complete the request if it is successfully removed from the xarray.

Fixes: e73fa11a35 ("cachefiles: add restore command to recover inflight ondemand read requests")
Suggested-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-4-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:29 +02:00
Baokun Li
0fc75c5940
cachefiles: remove requests from xarray during flushing requests
Even with CACHEFILES_DEAD set, we can still read the requests, so in the
following concurrency the request may be used after it has been freed:

     mount  |   daemon_thread1    |    daemon_thread2
------------------------------------------------------------
 cachefiles_ondemand_init_object
  cachefiles_ondemand_send_req
   REQ_A = kzalloc(sizeof(*req) + data_len)
   wait_for_completion(&REQ_A->done)
            cachefiles_daemon_read
             cachefiles_ondemand_daemon_read
                                  // close dev fd
                                  cachefiles_flush_reqs
                                   complete(&REQ_A->done)
   kfree(REQ_A)
              xa_lock(&cache->reqs);
              cachefiles_ondemand_select_req
                req->msg.opcode != CACHEFILES_OP_READ
                // req use-after-free !!!
              xa_unlock(&cache->reqs);
                                   xa_destroy(&cache->reqs)

Hence remove requests from cache->reqs when flushing them to avoid
accessing freed requests.

Fixes: c838305450 ("cachefiles: notify the user daemon when looking up cookie")
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240522114308.2402121-3-libaokun@huaweicloud.com
Acked-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jia Zhu <zhujia.zj@bytedance.com>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-05-29 13:03:29 +02:00
Linus Torvalds
b6394d6f71 Assorted commits that had missed the last merge window...
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Merge tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull misc vfs updates from Al Viro:
 "Assorted commits that had missed the last merge window..."

* tag 'pull-misc' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  remove call_{read,write}_iter() functions
  do_dentry_open(): kill inode argument
  kernel_file_open(): get rid of inode argument
  get_file_rcu(): no need to check for NULL separately
  fd_is_open(): move to fs/file.c
  close_on_exec(): pass files_struct instead of fdtable
2024-05-21 13:11:44 -07:00
David Howells
64e64e6c18 netfs, cachefiles: Implement helpers for new write code
Implement the helpers for the new write code in cachefiles.  There's now an
optional ->prepare_write() that allows the filesystem to set the parameters
for the next write, such as maximum size and maximum segment count, and an
->issue_write() that is called to initiate an (asynchronous) write
operation.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: netfs@lists.linux.dev
cc: linux-erofs@lists.ozlabs.org
cc: linux-fsdevel@vger.kernel.org
2024-05-01 18:07:37 +01:00
David Howells
7ba167c4c7 netfs: Switch to using unsigned long long rather than loff_t
Switch to using unsigned long long rather than loff_t in netfslib to avoid
problems with the sign flipping in the maths when we're dealing with the
byte at position 0x7fffffffffffffff.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Ilya Dryomov <idryomov@gmail.com>
cc: Xiubo Li <xiubli@redhat.com>
cc: netfs@lists.linux.dev
cc: ceph-devel@vger.kernel.org
cc: linux-fsdevel@vger.kernel.org
2024-05-01 18:07:35 +01:00
Al Viro
af58dc1f50 kernel_file_open(): get rid of inode argument
always equal to ->dentry->d_inode of the path argument these
days.

Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2024-04-15 16:03:24 -04:00
Baokun Li
e21a2f1756
cachefiles: fix memory leak in cachefiles_add_cache()
The following memory leak was reported after unbinding /dev/cachefiles:

==================================================================
unreferenced object 0xffff9b674176e3c0 (size 192):
  comm "cachefilesd2", pid 680, jiffies 4294881224
  hex dump (first 32 bytes):
    01 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace (crc ea38a44b):
    [<ffffffff8eb8a1a5>] kmem_cache_alloc+0x2d5/0x370
    [<ffffffff8e917f86>] prepare_creds+0x26/0x2e0
    [<ffffffffc002eeef>] cachefiles_determine_cache_security+0x1f/0x120
    [<ffffffffc00243ec>] cachefiles_add_cache+0x13c/0x3a0
    [<ffffffffc0025216>] cachefiles_daemon_write+0x146/0x1c0
    [<ffffffff8ebc4a3b>] vfs_write+0xcb/0x520
    [<ffffffff8ebc5069>] ksys_write+0x69/0xf0
    [<ffffffff8f6d4662>] do_syscall_64+0x72/0x140
    [<ffffffff8f8000aa>] entry_SYSCALL_64_after_hwframe+0x6e/0x76
==================================================================

Put the reference count of cache_cred in cachefiles_daemon_unbind() to
fix the problem. And also put cache_cred in cachefiles_add_cache() error
branch to avoid memory leaks.

Fixes: 9ae326a690 ("CacheFiles: A cache that backs onto a mounted filesystem")
CC: stable@vger.kernel.org
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240217081431.796809-1-libaokun1@huawei.com
Acked-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-20 09:46:07 +01:00
David Howells
c3d6569a43 cachefiles, erofs: Fix NULL deref in when cachefiles is not doing ondemand-mode
cachefiles_ondemand_init_object() as called from cachefiles_open_file() and
cachefiles_create_tmpfile() does not check if object->ondemand is set
before dereferencing it, leading to an oops something like:

	RIP: 0010:cachefiles_ondemand_init_object+0x9/0x41
	...
	Call Trace:
	 <TASK>
	 cachefiles_open_file+0xc9/0x187
	 cachefiles_lookup_cookie+0x122/0x2be
	 fscache_cookie_state_machine+0xbe/0x32b
	 fscache_cookie_worker+0x1f/0x2d
	 process_one_work+0x136/0x208
	 process_scheduled_works+0x3a/0x41
	 worker_thread+0x1a2/0x1f6
	 kthread+0xca/0xd2
	 ret_from_fork+0x21/0x33

Fix this by making cachefiles_ondemand_init_object() return immediately if
cachefiles->ondemand is NULL.

Fixes: 3c5ecfe16e ("cachefiles: extract ondemand info field from cachefiles_object")
Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Gao Xiang <xiang@kernel.org>
cc: Chao Yu <chao@kernel.org>
cc: Yue Hu <huyue2@coolpad.com>
cc: Jeffle Xu <jefflexu@linux.alibaba.com>
cc: linux-erofs@lists.ozlabs.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
2024-01-22 22:25:15 +00:00
Linus Torvalds
16df6e07d6 vfs-6.8.netfs
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Merge tag 'vfs-6.8.netfs' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs

Pull netfs updates from Christian Brauner:
 "This extends the netfs helper library that network filesystems can use
  to replace their own implementations. Both afs and 9p are ported. cifs
  is ready as well but the patches are way bigger and will be routed
  separately once this is merged. That will remove lots of code as well.

  The overal goal is to get high-level I/O and knowledge of the page
  cache and ouf of the filesystem drivers. This includes knowledge about
  the existence of pages and folios

  The pull request converts afs and 9p. This removes about 800 lines of
  code from afs and 300 from 9p. For 9p it is now possible to do writes
  in larger than a page chunks. Additionally, multipage folio support
  can be turned on for 9p. Separate patches exist for cifs removing
  another 2000+ lines. I've included detailed information in the
  individual pulls I took.

  Summary:

   - Add NFS-style (and Ceph-style) locking around DIO vs buffered I/O
     calls to prevent these from happening at the same time.

   - Support for direct and unbuffered I/O.

   - Support for write-through caching in the page cache.

   - O_*SYNC and RWF_*SYNC writes use write-through rather than writing
     to the page cache and then flushing afterwards.

   - Support for write-streaming.

   - Support for write grouping.

   - Skip reads for which the server could only return zeros or EOF.

   - The fscache module is now part of the netfs library and the
     corresponding maintainer entry is updated.

   - Some helpers from the fscache subsystem are renamed to mark them as
     belonging to the netfs library.

   - Follow-up fixes for the netfs library.

   - Follow-up fixes for the 9p conversion"

* tag 'vfs-6.8.netfs' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (50 commits)
  netfs: Fix wrong #ifdef hiding wait
  cachefiles: Fix signed/unsigned mixup
  netfs: Fix the loop that unmarks folios after writing to the cache
  netfs: Fix interaction between write-streaming and cachefiles culling
  netfs: Count DIO writes
  netfs: Mark netfs_unbuffered_write_iter_locked() static
  netfs: Fix proc/fs/fscache symlink to point to "netfs" not "../netfs"
  netfs: Rearrange netfs_io_subrequest to put request pointer first
  9p: Use length of data written to the server in preference to error
  9p: Do a couple of cleanups
  9p: Fix initialisation of netfs_inode for 9p
  cachefiles: Fix __cachefiles_prepare_write()
  9p: Use netfslib read/write_iter
  afs: Use the netfs write helpers
  netfs: Export the netfs_sreq tracepoint
  netfs: Optimise away reads above the point at which there can be no data
  netfs: Implement a write-through caching option
  netfs: Provide a launder_folio implementation
  netfs: Provide a writepages implementation
  netfs, cachefiles: Pass upper bound length to allow expansion
  ...
2024-01-19 09:10:23 -08:00
Linus Torvalds
bf4e7080ae fix directory locking scheme on rename
broken in 6.5; we really can't lock two unrelated directories
 without holding ->s_vfs_rename_mutex first and in case of
 same-parent rename of a subdirectory 6.5 ends up doing just
 that.
 
 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull rename updates from Al Viro:
 "Fix directory locking scheme on rename

  This was broken in 6.5; we really can't lock two unrelated directories
  without holding ->s_vfs_rename_mutex first and in case of same-parent
  rename of a subdirectory 6.5 ends up doing just that"

* tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  rename(): avoid a deadlock in the case of parents having no common ancestor
  kill lock_two_inodes()
  rename(): fix the locking of subdirectories
  f2fs: Avoid reading renamed directory if parent does not change
  ext4: don't access the source subdirectory content on same-directory rename
  ext2: Avoid reading renamed directory if parent does not change
  udf_rename(): only access the child content on cross-directory rename
  ocfs2: Avoid touching renamed directory if parent does not change
  reiserfs: Avoid touching renamed directory if parent does not change
2024-01-11 20:00:22 -08:00
Linus Torvalds
a05aea98d4 sysctl-6.8-rc1
To help make the move of sysctls out of kernel/sysctl.c not incur a size
 penalty sysctl has been changed to allow us to not require the sentinel, the
 final empty element on the sysctl array. Joel Granados has been doing all this
 work. On the v6.6 kernel we got the major infrastructure changes required to
 support this. For v6.7 we had all arch/ and drivers/ modified to remove
 the sentinel. For v6.8-rc1 we get a few more updates for fs/ directory only.
 The kernel/ directory is left but we'll save that for v6.9-rc1 as those patches
 are still being reviewed. After that we then can expect also the removal of the
 no longer needed check for procname == NULL.
 
 Let us recap the purpose of this work:
 
   - this helps reduce the overall build time size of the kernel and run time
     memory consumed by the kernel by about ~64 bytes per array
   - the extra 64-byte penalty is no longer inncurred now when we move sysctls
     out from kernel/sysctl.c to their own files
 
 Thomas Weißschuh also sent a few cleanups, for v6.9-rc1 we expect to see further
 work by Thomas Weißschuh with the constificatin of the struct ctl_table.
 
 Due to Joel Granados's work, and to help bring in new blood, I have suggested
 for him to become a maintainer and he's accepted. So for v6.9-rc1 I look forward
 to seeing him sent you a pull request for further sysctl changes. This also
 removes Iurii Zaikin as a maintainer as he has moved on to other projects and
 has had no time to help at all.
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Merge tag 'sysctl-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

Pull sysctl updates from Luis Chamberlain:
 "To help make the move of sysctls out of kernel/sysctl.c not incur a
  size penalty sysctl has been changed to allow us to not require the
  sentinel, the final empty element on the sysctl array. Joel Granados
  has been doing all this work.

  In the v6.6 kernel we got the major infrastructure changes required to
  support this. For v6.7 we had all arch/ and drivers/ modified to
  remove the sentinel. For v6.8-rc1 we get a few more updates for fs/
  directory only.

  The kernel/ directory is left but we'll save that for v6.9-rc1 as
  those patches are still being reviewed. After that we then can expect
  also the removal of the no longer needed check for procname == NULL.

  Let us recap the purpose of this work:

   - this helps reduce the overall build time size of the kernel and run
     time memory consumed by the kernel by about ~64 bytes per array

   - the extra 64-byte penalty is no longer inncurred now when we move
     sysctls out from kernel/sysctl.c to their own files

  Thomas Weißschuh also sent a few cleanups, for v6.9-rc1 we expect to
  see further work by Thomas Weißschuh with the constificatin of the
  struct ctl_table.

  Due to Joel Granados's work, and to help bring in new blood, I have
  suggested for him to become a maintainer and he's accepted. So for
  v6.9-rc1 I look forward to seeing him sent you a pull request for
  further sysctl changes. This also removes Iurii Zaikin as a maintainer
  as he has moved on to other projects and has had no time to help at
  all"

* tag 'sysctl-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
  sysctl: remove struct ctl_path
  sysctl: delete unused define SYSCTL_PERM_EMPTY_DIR
  coda: Remove the now superfluous sentinel elements from ctl_table array
  sysctl: Remove the now superfluous sentinel elements from ctl_table array
  fs: Remove the now superfluous sentinel elements from ctl_table array
  cachefiles: Remove the now superfluous sentinel element from ctl_table array
  sysclt: Clarify the results of selftest run
  sysctl: Add a selftest for handling empty dirs
  sysctl: Fix out of bounds access for empty sysctl registers
  MAINTAINERS: Add Joel Granados as co-maintainer for proc sysctl
  MAINTAINERS: remove Iurii Zaikin from proc sysctl
2024-01-10 17:44:36 -08:00
David Howells
3d1d4aa0cc cachefiles: Fix signed/unsigned mixup
In __cachefiles_prepare_write(), the start and pos variables were made
unsigned 64-bit so that the casts in the checking could be got rid of -
which should be fine since absolute file offsets can't be negative, except
that an error code may be obtained from vfs_llseek(), which *would* be
negative.  This breaks the error check.

Fix this for now by reverting pos and start to be signed and putting back
the casts.  Unfortunately, the error value checks cannot be replaced with
IS_ERR_VALUE() as long might be 32-bits.

Fixes: 7097c96411 ("cachefiles: Fix __cachefiles_prepare_write()")
Reported-by: Simon Horman <horms@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202401071152.DbKqMQMu-lkp@intel.com/
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: Gao Xiang <hsiangkao@linux.alibaba.com>
cc: Yiqun Leng <yqleng@linux.alibaba.com>
cc: Jia Zhu <zhujia.zj@bytedance.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-erofs@lists.ozlabs.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
2024-01-09 13:32:44 +00:00
Linus Torvalds
26458409a9 vfs-6.8.cachefiles
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Merge tag 'vfs-6.8.cachefiles' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs cachefiles updates from Christian Brauner:
 "This contains improvements for on-demand cachefiles.

  If the daemon crashes and the on-demand cachefiles fd is unexpectedly
  closed in-flight requests and subsequent read operations associated
  with the fd will fail with EIO. This causes issues in various
  scenarios as this failure is currently unrecoverable.

  The work contained in this pull request introduces a failover mode and
  enables the daemon to recover in-flight requested-related objects. A
  restarted daemon will be able to process requests as usual.

  This requires that in-flight requests are stored during daemon crash
  or while the daemon is offline. In addition, a handle to
  /dev/cachefiles needs to be stored.

  This can be done by e.g., systemd's fdstore (cf. [1]) which enables
  the restarted daemon to recover state.

  Three new states are introduced in this patchset:

   (1) CLOSE
       Object is closed by the daemon.

   (2) OPEN
       Object is open and ready for processing. IOW, the open request
       has been handled successfully.

   (3) REOPENING
       Object has been previously closed and is now reopened due to a
       read request.

  A restarted daemon can recover the /dev/cachefiles fd from systemd's
  fdstore and writes "restore" to the device. This causes the object
  state to be reset from CLOSE to REOPENING and reinitializes the
  object.

  The daemon may now handle the open request. Any in-flight operations
  are restored and handled avoiding interruptions for users"

Link: https://systemd.io/FILE_DESCRIPTOR_STORE [1]

* tag 'vfs-6.8.cachefiles' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  cachefiles: add restore command to recover inflight ondemand read requests
  cachefiles: narrow the scope of triggering EPOLLIN events in ondemand mode
  cachefiles: resend an open request if the read request's object is closed
  cachefiles: extract ondemand info field from cachefiles_object
  cachefiles: introduce object ondemand state
2024-01-08 11:26:50 -08:00
David Howells
92a714d727 netfs: Fix interaction between write-streaming and cachefiles culling
An issue can occur between write-streaming (storing dirty data in partial
non-uptodate pages) and a cachefiles object being culled to make space.
The problem occurs because the cache object is only marked in use while
there are files open using it.  Once it has been released, it can be culled
and the cookie marked disabled.

At this point, a streaming write is permitted to occur (if the cache is
active, we require pages to be prefetched and cached), but the cache can
become active again before this gets flushed out - and then two effects can
occur:

 (1) The cache may be asked to write out a region that's less than its DIO
     block size (assumed by cachefiles to be PAGE_SIZE) - and this causes
     one of two debugging statements to be emitted.

 (2) netfs_how_to_modify() gets confused because it sees a page that isn't
     allowed to be non-uptodate being uptodate and tries to prefetch it -
     leading to a warning that PG_fscache is set twice.

Fix this by the following means:

 (1) Add a netfs_inode flag to disallow write-streaming to an inode and set
     it if we ever do local caching of that inode.  It remains set for the
     lifetime of that inode - even if the cookie becomes disabled.

 (2) If the no-write-streaming flag is set, then make netfs_how_to_modify()
     always want to prefetch instead.

 (3) If netfs_how_to_modify() decides it wants to prefetch a folio, but
     that folio has write-streamed data in it, then it requires the folio
     be flushed first.

 (4) Export a counter of the number of times we wanted to prefetch a
     non-uptodate page, but found it had write-streamed data in it.

 (5) Export a counter of the number of times we cancelled a write to the
     cache because it didn't DIO align and remove the debug statements.

Reported-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David Howells <dhowells@redhat.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-erofs@lists.ozlabs.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
2024-01-05 15:42:25 +00:00
David Howells
7097c96411 cachefiles: Fix __cachefiles_prepare_write()
Fix __cachefiles_prepare_write() to correctly determine whether the
requested write will fit correctly with the DIO alignment.

Reported-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Tested-by: Yiqun Leng <yqleng@linux.alibaba.com>
Tested-by: Jia Zhu <zhujia.zj@bytedance.com>
cc: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-erofs@lists.ozlabs.org
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
2024-01-03 14:52:53 +00:00
Joel Granados
e640fc5b7b cachefiles: Remove the now superfluous sentinel element from ctl_table array
This commit comes at the tail end of a greater effort to remove the empty
elements at the end of the ctl_table arrays (sentinels) which will reduce the
overall build time size of the kernel and run time memory bloat by ~64 bytes
per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove sentinel from cachefiles_sysctls

Signed-off-by: Joel Granados <j.granados@samsung.com>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2023-12-28 04:57:57 -08:00
David Howells
e0ace6ca98 netfs, cachefiles: Pass upper bound length to allow expansion
Make netfslib pass the maximum length to the ->prepare_write() op to tell
the cache how much it can expand the length of a write to.  This allows a
write to the server at the end of a file to be limited to a few bytes
whilst writing an entire block to the cache (something required by direct
I/O).

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: linux-cachefs@redhat.com
cc: linux-fsdevel@vger.kernel.org
cc: linux-mm@kvack.org
2023-12-28 09:45:25 +00:00
David Howells
915cd30cde netfs, fscache: Combine fscache with netfs
Now that the fscache code is moved to be colocated with the netfslib code
so that they combined into one module, do the combining.

Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
cc: Christian Brauner <christian@brauner.io>
cc: linux-fsdevel@vger.kernel.org
cc: linux-cachefs@redhat.com
cc: linux-nfs@vger.kernel.org,
cc: linux-erofs@lists.ozlabs.org
2023-12-24 15:08:46 +00:00
Jia Zhu
e73fa11a35
cachefiles: add restore command to recover inflight ondemand read requests
Previously, in ondemand read scenario, if the anonymous fd was closed by
user daemon, inflight and subsequent read requests would return EIO.
As long as the device connection is not released, user daemon can hold
and restore inflight requests by setting the request flag to
CACHEFILES_REQ_NEW.

Suggested-by: Gao Xiang <hsiangkao@linux.alibaba.com>
Signed-off-by: Jia Zhu <zhujia.zj@bytedance.com>
Signed-off-by: Xin Yin <yinxin.x@bytedance.com>
Link: https://lore.kernel.org/r/20231120041422.75170-6-zhujia.zj@bytedance.com
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-11-25 16:03:57 +01:00
Jia Zhu
b817e22b2e
cachefiles: narrow the scope of triggering EPOLLIN events in ondemand mode
Don't trigger EPOLLIN when there are only reopening read requests in
xarray.

Suggested-by: Xin Yin <yinxin.x@bytedance.com>
Signed-off-by: Jia Zhu <zhujia.zj@bytedance.com>
Link: https://lore.kernel.org/r/20231120041422.75170-5-zhujia.zj@bytedance.com
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-11-25 16:03:57 +01:00
Jia Zhu
0a7e54c195
cachefiles: resend an open request if the read request's object is closed
When an anonymous fd is closed by user daemon, if there is a new read
request for this file comes up, the anonymous fd should be re-opened
to handle that read request rather than fail it directly.

1. Introduce reopening state for objects that are closed but have
   inflight/subsequent read requests.
2. No longer flush READ requests but only CLOSE requests when anonymous
   fd is closed.
3. Enqueue the reopen work to workqueue, thus user daemon could get rid
   of daemon_read context and handle that request smoothly. Otherwise,
   the user daemon will send a reopen request and wait for itself to
   process the request.

Signed-off-by: Jia Zhu <zhujia.zj@bytedance.com>
Link: https://lore.kernel.org/r/20231120041422.75170-4-zhujia.zj@bytedance.com
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-11-25 16:03:57 +01:00
Jia Zhu
3c5ecfe16e
cachefiles: extract ondemand info field from cachefiles_object
We'll introduce a @work_struct field for @object in subsequent patches,
it will enlarge the size of @object.
As the result of that, this commit extracts ondemand info field from
@object.

Signed-off-by: Jia Zhu <zhujia.zj@bytedance.com>
Link: https://lore.kernel.org/r/20231120041422.75170-3-zhujia.zj@bytedance.com
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-11-25 16:03:57 +01:00
Jia Zhu
357a18d033
cachefiles: introduce object ondemand state
Previously, @ondemand_id field was used not only to identify ondemand
state of the object, but also to represent the index of the xarray.
This commit introduces @state field to decouple the role of @ondemand_id
and adds helpers to access it.

Signed-off-by: Jia Zhu <zhujia.zj@bytedance.com>
Link: https://lore.kernel.org/r/20231120041422.75170-2-zhujia.zj@bytedance.com
Reviewed-by: Jingbo Xu <jefflexu@linux.alibaba.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-11-25 16:03:54 +01:00
Al Viro
a8b0026847 rename(): avoid a deadlock in the case of parents having no common ancestor
... and fix the directory locking documentation and proof of correctness.
Holding ->s_vfs_rename_mutex *almost* prevents ->d_parent changes; the
case where we really don't want it is splicing the root of disconnected
tree to somewhere.

In other words, ->s_vfs_rename_mutex is sufficient to stabilize "X is an
ancestor of Y" only if X and Y are already in the same tree.  Otherwise
it can go from false to true, and one can construct a deadlock on that.

Make lock_two_directories() report an error in such case and update the
callers of lock_rename()/lock_rename_child() to handle such errors.

And yes, such conditions are not impossible to create ;-/

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2023-11-25 02:54:14 -05:00
Amir Goldstein
6ae654392b fs: move kiocb_start_write() into vfs_iocb_iter_write()
In vfs code, sb_start_write() is usually called after the permission hook
in rw_verify_area().  vfs_iocb_iter_write() is an exception to this rule,
where kiocb_start_write() is called by its callers.

Move kiocb_start_write() from the callers into vfs_iocb_iter_write()
after the rw_verify_area() checks, to make them "start-write-safe".

The semantics of vfs_iocb_iter_write() is changed, so that the caller is
responsible for calling kiocb_end_write() on completion only if async
iocb was queued.  The completion handlers of both callers were adapted
to this semantic change.

This is needed for fanotify "pre content" events.

Suggested-by: Jan Kara <jack@suse.cz>
Suggested-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231122122715.2561213-14-amir73il@gmail.com
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-11-24 10:37:44 +01:00
Linus Torvalds
b96a3e9142 - Some swap cleanups from Ma Wupeng ("fix WARN_ON in add_to_avail_list")
- Peter Xu has a series (mm/gup: Unify hugetlb, speed up thp") which
   reduces the special-case code for handling hugetlb pages in GUP.  It
   also speeds up GUP handling of transparent hugepages.
 
 - Peng Zhang provides some maple tree speedups ("Optimize the fast path
   of mas_store()").
 
 - Sergey Senozhatsky has improved te performance of zsmalloc during
   compaction (zsmalloc: small compaction improvements").
 
 - Domenico Cerasuolo has developed additional selftest code for zswap
   ("selftests: cgroup: add zswap test program").
 
 - xu xin has doe some work on KSM's handling of zero pages.  These
   changes are mainly to enable the user to better understand the
   effectiveness of KSM's treatment of zero pages ("ksm: support tracking
   KSM-placed zero-pages").
 
 - Jeff Xu has fixes the behaviour of memfd's
   MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED sysctl ("mm/memfd: fix sysctl
   MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED").
 
 - David Howells has fixed an fscache optimization ("mm, netfs, fscache:
   Stop read optimisation when folio removed from pagecache").
 
 - Axel Rasmussen has given userfaultfd the ability to simulate memory
   poisoning ("add UFFDIO_POISON to simulate memory poisoning with UFFD").
 
 - Miaohe Lin has contributed some routine maintenance work on the
   memory-failure code ("mm: memory-failure: remove unneeded PageHuge()
   check").
 
 - Peng Zhang has contributed some maintenance work on the maple tree
   code ("Improve the validation for maple tree and some cleanup").
 
 - Hugh Dickins has optimized the collapsing of shmem or file pages into
   THPs ("mm: free retracted page table by RCU").
 
 - Jiaqi Yan has a patch series which permits us to use the healthy
   subpages within a hardware poisoned huge page for general purposes
   ("Improve hugetlbfs read on HWPOISON hugepages").
 
 - Kemeng Shi has done some maintenance work on the pagetable-check code
   ("Remove unused parameters in page_table_check").
 
 - More folioification work from Matthew Wilcox ("More filesystem folio
   conversions for 6.6"), ("Followup folio conversions for zswap").  And
   from ZhangPeng ("Convert several functions in page_io.c to use a
   folio").
 
 - page_ext cleanups from Kemeng Shi ("minor cleanups for page_ext").
 
 - Baoquan He has converted some architectures to use the GENERIC_IOREMAP
   ioremap()/iounmap() code ("mm: ioremap: Convert architectures to take
   GENERIC_IOREMAP way").
 
 - Anshuman Khandual has optimized arm64 tlb shootdown ("arm64: support
   batched/deferred tlb shootdown during page reclamation/migration").
 
 - Better maple tree lockdep checking from Liam Howlett ("More strict
   maple tree lockdep").  Liam also developed some efficiency improvements
   ("Reduce preallocations for maple tree").
 
 - Cleanup and optimization to the secondary IOMMU TLB invalidation, from
   Alistair Popple ("Invalidate secondary IOMMU TLB on permission
   upgrade").
 
 - Ryan Roberts fixes some arm64 MM selftest issues ("selftests/mm fixes
   for arm64").
 
 - Kemeng Shi provides some maintenance work on the compaction code ("Two
   minor cleanups for compaction").
 
 - Some reduction in mmap_lock pressure from Matthew Wilcox ("Handle most
   file-backed faults under the VMA lock").
 
 - Aneesh Kumar contributes code to use the vmemmap optimization for DAX
   on ppc64, under some circumstances ("Add support for DAX vmemmap
   optimization for ppc64").
 
 - page-ext cleanups from Kemeng Shi ("add page_ext_data to get client
   data in page_ext"), ("minor cleanups to page_ext header").
 
 - Some zswap cleanups from Johannes Weiner ("mm: zswap: three
   cleanups").
 
 - kmsan cleanups from ZhangPeng ("minor cleanups for kmsan").
 
 - VMA handling cleanups from Kefeng Wang ("mm: convert to
   vma_is_initial_heap/stack()").
 
 - DAMON feature work from SeongJae Park ("mm/damon/sysfs-schemes:
   implement DAMOS tried total bytes file"), ("Extend DAMOS filters for
   address ranges and DAMON monitoring targets").
 
 - Compaction work from Kemeng Shi ("Fixes and cleanups to compaction").
 
 - Liam Howlett has improved the maple tree node replacement code
   ("maple_tree: Change replacement strategy").
 
 - ZhangPeng has a general code cleanup - use the K() macro more widely
   ("cleanup with helper macro K()").
 
 - Aneesh Kumar brings memmap-on-memory to ppc64 ("Add support for memmap
   on memory feature on ppc64").
 
 - pagealloc cleanups from Kemeng Shi ("Two minor cleanups for pcp list
   in page_alloc"), ("Two minor cleanups for get pageblock migratetype").
 
 - Vishal Moola introduces a memory descriptor for page table tracking,
   "struct ptdesc" ("Split ptdesc from struct page").
 
 - memfd selftest maintenance work from Aleksa Sarai ("memfd: cleanups
   for vm.memfd_noexec").
 
 - MM include file rationalization from Hugh Dickins ("arch: include
   asm/cacheflush.h in asm/hugetlb.h").
 
 - THP debug output fixes from Hugh Dickins ("mm,thp: fix sloppy text
   output").
 
 - kmemleak improvements from Xiaolei Wang ("mm/kmemleak: use
   object_cache instead of kmemleak_initialized").
 
 - More folio-related cleanups from Matthew Wilcox ("Remove _folio_dtor
   and _folio_order").
 
 - A VMA locking scalability improvement from Suren Baghdasaryan
   ("Per-VMA lock support for swap and userfaults").
 
 - pagetable handling cleanups from Matthew Wilcox ("New page table range
   API").
 
 - A batch of swap/thp cleanups from David Hildenbrand ("mm/swap: stop
   using page->private on tail pages for THP_SWAP + cleanups").
 
 - Cleanups and speedups to the hugetlb fault handling from Matthew
   Wilcox ("Change calling convention for ->huge_fault").
 
 - Matthew Wilcox has also done some maintenance work on the MM subsystem
   documentation ("Improve mm documentation").
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Merge tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - Some swap cleanups from Ma Wupeng ("fix WARN_ON in
   add_to_avail_list")

 - Peter Xu has a series (mm/gup: Unify hugetlb, speed up thp") which
   reduces the special-case code for handling hugetlb pages in GUP. It
   also speeds up GUP handling of transparent hugepages.

 - Peng Zhang provides some maple tree speedups ("Optimize the fast path
   of mas_store()").

 - Sergey Senozhatsky has improved te performance of zsmalloc during
   compaction (zsmalloc: small compaction improvements").

 - Domenico Cerasuolo has developed additional selftest code for zswap
   ("selftests: cgroup: add zswap test program").

 - xu xin has doe some work on KSM's handling of zero pages. These
   changes are mainly to enable the user to better understand the
   effectiveness of KSM's treatment of zero pages ("ksm: support
   tracking KSM-placed zero-pages").

 - Jeff Xu has fixes the behaviour of memfd's
   MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED sysctl ("mm/memfd: fix sysctl
   MEMFD_NOEXEC_SCOPE_NOEXEC_ENFORCED").

 - David Howells has fixed an fscache optimization ("mm, netfs, fscache:
   Stop read optimisation when folio removed from pagecache").

 - Axel Rasmussen has given userfaultfd the ability to simulate memory
   poisoning ("add UFFDIO_POISON to simulate memory poisoning with
   UFFD").

 - Miaohe Lin has contributed some routine maintenance work on the
   memory-failure code ("mm: memory-failure: remove unneeded PageHuge()
   check").

 - Peng Zhang has contributed some maintenance work on the maple tree
   code ("Improve the validation for maple tree and some cleanup").

 - Hugh Dickins has optimized the collapsing of shmem or file pages into
   THPs ("mm: free retracted page table by RCU").

 - Jiaqi Yan has a patch series which permits us to use the healthy
   subpages within a hardware poisoned huge page for general purposes
   ("Improve hugetlbfs read on HWPOISON hugepages").

 - Kemeng Shi has done some maintenance work on the pagetable-check code
   ("Remove unused parameters in page_table_check").

 - More folioification work from Matthew Wilcox ("More filesystem folio
   conversions for 6.6"), ("Followup folio conversions for zswap"). And
   from ZhangPeng ("Convert several functions in page_io.c to use a
   folio").

 - page_ext cleanups from Kemeng Shi ("minor cleanups for page_ext").

 - Baoquan He has converted some architectures to use the
   GENERIC_IOREMAP ioremap()/iounmap() code ("mm: ioremap: Convert
   architectures to take GENERIC_IOREMAP way").

 - Anshuman Khandual has optimized arm64 tlb shootdown ("arm64: support
   batched/deferred tlb shootdown during page reclamation/migration").

 - Better maple tree lockdep checking from Liam Howlett ("More strict
   maple tree lockdep"). Liam also developed some efficiency
   improvements ("Reduce preallocations for maple tree").

 - Cleanup and optimization to the secondary IOMMU TLB invalidation,
   from Alistair Popple ("Invalidate secondary IOMMU TLB on permission
   upgrade").

 - Ryan Roberts fixes some arm64 MM selftest issues ("selftests/mm fixes
   for arm64").

 - Kemeng Shi provides some maintenance work on the compaction code
   ("Two minor cleanups for compaction").

 - Some reduction in mmap_lock pressure from Matthew Wilcox ("Handle
   most file-backed faults under the VMA lock").

 - Aneesh Kumar contributes code to use the vmemmap optimization for DAX
   on ppc64, under some circumstances ("Add support for DAX vmemmap
   optimization for ppc64").

 - page-ext cleanups from Kemeng Shi ("add page_ext_data to get client
   data in page_ext"), ("minor cleanups to page_ext header").

 - Some zswap cleanups from Johannes Weiner ("mm: zswap: three
   cleanups").

 - kmsan cleanups from ZhangPeng ("minor cleanups for kmsan").

 - VMA handling cleanups from Kefeng Wang ("mm: convert to
   vma_is_initial_heap/stack()").

 - DAMON feature work from SeongJae Park ("mm/damon/sysfs-schemes:
   implement DAMOS tried total bytes file"), ("Extend DAMOS filters for
   address ranges and DAMON monitoring targets").

 - Compaction work from Kemeng Shi ("Fixes and cleanups to compaction").

 - Liam Howlett has improved the maple tree node replacement code
   ("maple_tree: Change replacement strategy").

 - ZhangPeng has a general code cleanup - use the K() macro more widely
   ("cleanup with helper macro K()").

 - Aneesh Kumar brings memmap-on-memory to ppc64 ("Add support for
   memmap on memory feature on ppc64").

 - pagealloc cleanups from Kemeng Shi ("Two minor cleanups for pcp list
   in page_alloc"), ("Two minor cleanups for get pageblock
   migratetype").

 - Vishal Moola introduces a memory descriptor for page table tracking,
   "struct ptdesc" ("Split ptdesc from struct page").

 - memfd selftest maintenance work from Aleksa Sarai ("memfd: cleanups
   for vm.memfd_noexec").

 - MM include file rationalization from Hugh Dickins ("arch: include
   asm/cacheflush.h in asm/hugetlb.h").

 - THP debug output fixes from Hugh Dickins ("mm,thp: fix sloppy text
   output").

 - kmemleak improvements from Xiaolei Wang ("mm/kmemleak: use
   object_cache instead of kmemleak_initialized").

 - More folio-related cleanups from Matthew Wilcox ("Remove _folio_dtor
   and _folio_order").

 - A VMA locking scalability improvement from Suren Baghdasaryan
   ("Per-VMA lock support for swap and userfaults").

 - pagetable handling cleanups from Matthew Wilcox ("New page table
   range API").

 - A batch of swap/thp cleanups from David Hildenbrand ("mm/swap: stop
   using page->private on tail pages for THP_SWAP + cleanups").

 - Cleanups and speedups to the hugetlb fault handling from Matthew
   Wilcox ("Change calling convention for ->huge_fault").

 - Matthew Wilcox has also done some maintenance work on the MM
   subsystem documentation ("Improve mm documentation").

* tag 'mm-stable-2023-08-28-18-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (489 commits)
  maple_tree: shrink struct maple_tree
  maple_tree: clean up mas_wr_append()
  secretmem: convert page_is_secretmem() to folio_is_secretmem()
  nios2: fix flush_dcache_page() for usage from irq context
  hugetlb: add documentation for vma_kernel_pagesize()
  mm: add orphaned kernel-doc to the rst files.
  mm: fix clean_record_shared_mapping_range kernel-doc
  mm: fix get_mctgt_type() kernel-doc
  mm: fix kernel-doc warning from tlb_flush_rmaps()
  mm: remove enum page_entry_size
  mm: allow ->huge_fault() to be called without the mmap_lock held
  mm: move PMD_ORDER to pgtable.h
  mm: remove checks for pte_index
  memcg: remove duplication detection for mem_cgroup_uncharge_swap
  mm/huge_memory: work on folio->swap instead of page->private when splitting folio
  mm/swap: inline folio_set_swap_entry() and folio_swap_entry()
  mm/swap: use dedicated entry for swap in folio
  mm/swap: stop using page->private on tail pages for THP_SWAP
  selftests/mm: fix WARNING comparing pointer to 0
  selftests: cgroup: fix test_kmem_memcg_deletion kernel mem check
  ...
2023-08-29 14:25:26 -07:00
Amir Goldstein
e6fa4c728f cachefiles: use kiocb_{start,end}_write() helpers
Use helpers instead of the open coded dance to silence lockdep warnings.

Suggested-by: Jan Kara <jack@suse.cz>
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Message-Id: <20230817141337.1025891-8-amir73il@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-08-21 17:27:27 +02:00
David Howells
b4fa966f03 mm, netfs, fscache: stop read optimisation when folio removed from pagecache
Fscache has an optimisation by which reads from the cache are skipped
until we know that (a) there's data there to be read and (b) that data
isn't entirely covered by pages resident in the netfs pagecache.  This is
done with two flags manipulated by fscache_note_page_release():

	if (...
	    test_bit(FSCACHE_COOKIE_HAVE_DATA, &cookie->flags) &&
	    test_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags))
		clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &cookie->flags);

where the NO_DATA_TO_READ flag causes cachefiles_prepare_read() to
indicate that netfslib should download from the server or clear the page
instead.

The fscache_note_page_release() function is intended to be called from
->releasepage() - but that only gets called if PG_private or PG_private_2
is set - and currently the former is at the discretion of the network
filesystem and the latter is only set whilst a page is being written to
the cache, so sometimes we miss clearing the optimisation.

Fix this by following Willy's suggestion[1] and adding an address_space
flag, AS_RELEASE_ALWAYS, that causes filemap_release_folio() to always call
->release_folio() if it's set, even if PG_private or PG_private_2 aren't
set.

Note that this would require folio_test_private() and page_has_private() to
become more complicated.  To avoid that, in the places[*] where these are
used to conditionalise calls to filemap_release_folio() and
try_to_release_page(), the tests are removed the those functions just
jumped to unconditionally and the test is performed there.

[*] There are some exceptions in vmscan.c where the check guards more than
just a call to the releaser.  I've added a function, folio_needs_release()
to wrap all the checks for that.

AS_RELEASE_ALWAYS should be set if a non-NULL cookie is obtained from
fscache and cleared in ->evict_inode() before truncate_inode_pages_final()
is called.

Additionally, the FSCACHE_COOKIE_NO_DATA_TO_READ flag needs to be cleared
and the optimisation cancelled if a cachefiles object already contains data
when we open it.

[dwysocha@redhat.com: call folio_mapping() inside folio_needs_release()]
  Link: 902c990e31
Link: https://lkml.kernel.org/r/20230628104852.3391651-3-dhowells@redhat.com
Fixes: 1f67e6d0b1 ("fscache: Provide a function to note the release of a page")
Fixes: 047487c947 ("cachefiles: Implement the I/O routines")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Dave Wysochanski <dwysocha@redhat.com>
Reported-by: Rohith Surabattula <rohiths.msft@gmail.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Tested-by: SeongJae Park <sj@kernel.org>
Cc: Daire Byrne <daire.byrne@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Steve French <sfrench@samba.org>
Cc: Shyam Prasad N <nspmangalore@gmail.com>
Cc: Rohith Surabattula <rohiths.msft@gmail.com>
Cc: Dave Wysochanski <dwysocha@redhat.com>
Cc: Dominique Martinet <asmadeus@codewreck.org>
Cc: Ilya Dryomov <idryomov@gmail.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Jingbo Xu <jefflexu@linux.alibaba.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Xiubo Li <xiubli@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-08-18 10:12:13 -07:00
Linus Torvalds
1f2300a738 v6.5/vfs.file
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Merge tag 'v6.5/vfs.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs file handling updates from Christian Brauner:
 "This contains Amir's work to fix a long-standing problem where an
  unprivileged overlayfs mount can be used to avoid fanotify permission
  events that were requested for an inode or superblock on the
  underlying filesystem.

  Some background about files opened in overlayfs. If a file is opened
  in overlayfs @file->f_path will refer to a "fake" path. What this
  means is that while @file->f_inode will refer to inode of the
  underlying layer, @file->f_path refers to an overlayfs
  {dentry,vfsmount} pair. The reasons for doing this are out of scope
  here but it is the reason why the vfs has been providing the
  open_with_fake_path() helper for overlayfs for very long time now. So
  nothing new here.

  This is for sure not very elegant and everyone including the overlayfs
  maintainers agree. Improving this significantly would involve more
  fragile and potentially rather invasive changes.

  In various codepaths access to the path of the underlying filesystem
  is needed for such hybrid file. The best example is fsnotify where
  this becomes security relevant. Passing the overlayfs
  @file->f_path->dentry will cause fsnotify to skip generating fsnotify
  events registered on the underlying inode or superblock.

  To fix this we extend the vfs provided open_with_fake_path() concept
  for overlayfs to create a backing file container that holds the real
  path and to expose a helper that can be used by relevant callers to
  get access to the path of the underlying filesystem through the new
  file_real_path() helper. This pattern is similar to what we do in
  d_real() and d_real_inode().

  The first beneficiary is fsnotify and fixes the security sensitive
  problem mentioned above.

  There's a couple of nice cleanups included as well.

  Over time, the old open_with_fake_path() helper added specifically for
  overlayfs a long time ago started to get used in other places such as
  cachefiles. Even though cachefiles have nothing to do with hybrid
  files.

  The only reason cachefiles used that concept was that files opened
  with open_with_fake_path() aren't charged against the caller's open
  file limit by raising FMODE_NOACCOUNT. It's just mere coincidence that
  both overlayfs and cachefiles need to ensure to not overcharge the
  caller for their internal open calls.

  So this work disentangles FMODE_NOACCOUNT use cases and backing file
  use-cases by adding the FMODE_BACKING flag which indicates that the
  file can be used to retrieve the backing file of another filesystem.
  (Fyi, Jens will be sending you a really nice cleanup from Christoph
  that gets rid of 3 FMODE_* flags otherwise this would be the last
  fmode_t bit we'd be using.)

  So now overlayfs becomes the sole user of the renamed
  open_with_fake_path() helper which is now named backing_file_open().
  For internal kernel users such as cachefiles that are only interested
  in FMODE_NOACCOUNT but not in FMODE_BACKING we add a new
  kernel_file_open() helper which opens a file without being charged
  against the caller's open file limit. All new helpers are properly
  documented and clearly annotated to mention their special uses.

  We also rename vfs_tmpfile_open() to kernel_tmpfile_open() to clearly
  distinguish it from vfs_tmpfile() and align it the other kernel_*()
  internal helpers"

* tag 'v6.5/vfs.file' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  ovl: enable fsnotify events on underlying real files
  fs: use backing_file container for internal files with "fake" f_path
  fs: move kmem_cache_zalloc() into alloc_empty_file*() helpers
  fs: use a helper for opening kernel internal files
  fs: rename {vfs,kernel}_tmpfile_open()
2023-06-26 10:14:36 -07:00