linux-toradex.git/fs/afs, branch toradex_4.20.y

afs: Fix race in async call refcounting

2019-02-27T09:09:50+00:00

[ Upstream commit 34fa47612bfe5d7de7fcaf658a6952b6aeec3b13 ]

There's a race between afs_make_call() and afs_wake_up_async_call() in the
case that an error is returned from rxrpc_kernel_send_data() after it has
queued the final packet.

afs_make_call() will try and clean up the mess, but the call state may have
been moved on thereby causing afs_process_async_call() to also try and to
delete the call.

Fix this by:

 (1) Getting an extra ref for an asynchronous call for the call itself to
     hold.  This makes sure the call doesn't evaporate on us accidentally
     and will allow the call to be retained by the caller in a future
     patch.  The ref is released on leaving afs_make_call() or
     afs_wait_for_call_to_complete().

 (2) In the event of an error from rxrpc_kernel_send_data():

     (a) Don't set the call state to AFS_CALL_COMPLETE until *after* the
     	 call has been aborted and ended.  This prevents
     	 afs_deliver_to_call() from doing anything with any notifications
     	 it gets.

     (b) Explicitly end the call immediately to prevent further callbacks.

     (c) Cancel any queued async_work and wait for the work if it's
     	 executing.  This allows us to be sure the race won't recur when we
     	 change the state.  We put the work queue's ref on the call if we
     	 managed to cancel it.

     (d) Put the call's ref that we got in (1).  This belongs to us as long
     	 as the call is in state AFS_CALL_CL_REQUESTING.

Fixes: 341f741f04be ("afs: Refcount the afs_call struct")
Signed-off-by: David Howells 
Signed-off-by: Sasha Levin

afs: Provide a function to get a ref on a call

2019-02-27T09:09:50+00:00

[ Upstream commit 7a75b0079a1d54e342c502c3c8107ba97e05d3d3 ]

Provide a function to get a reference on an afs_call struct.

Signed-off-by: David Howells 
Signed-off-by: Sasha Levin

afs: Fix key refcounting in file locking code

2019-02-27T09:09:50+00:00

[ Upstream commit 59d49076ae3e6912e6d7df2fd68e2337f3d02036 ]

Fix the refcounting of the authentication keys in the file locking code.
The vnode->lock_key member points to a key on which it expects to be
holding a ref, but it isn't always given an extra ref, however.

Fixes: 0fafdc9f888b ("afs: Fix file locking")
Signed-off-by: David Howells 
Signed-off-by: Sasha Levin

afs: Don't set vnode->cb_s_break in afs_validate()

2019-02-27T09:09:50+00:00

[ Upstream commit 4882a27cec24319d10f95e978ecc80050e3e3e15 ]

A cb_interest record is not necessarily attached to the vnode on entry to
afs_validate(), which can cause an oops when we try to bring the vnode's
cb_s_break up to date in the default case (ie. no current callback promise
and the vnode has not been deleted).

Fix this by simply removing the line, as vnode->cb_s_break will be set when
needed by afs_register_server_cb_interest() when we next get a callback
promise from RPC call.

The oops looks something like:

    BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
    ...
    RIP: 0010:afs_validate+0x66/0x250 [kafs]
    ...
    Call Trace:
     afs_d_revalidate+0x8d/0x340 [kafs]
     ? __d_lookup+0x61/0x150
     lookup_dcache+0x44/0x70
     ? lookup_dcache+0x44/0x70
     __lookup_hash+0x24/0xa0
     do_unlinkat+0x11d/0x2c0
     __x64_sys_unlink+0x23/0x30
     do_syscall_64+0x4d/0xf0
     entry_SYSCALL_64_after_hwframe+0x44/0xa9

Fixes: ae3b7361dc0e ("afs: Fix validation/callback interaction")
Signed-off-by: Marc Dionne 
Signed-off-by: David Howells 
Signed-off-by: Sasha Levin

afs: Set correct lock type for the yfs CreateFile

2019-02-27T09:09:46+00:00

[ Upstream commit 5edc22cc1d33d6a88d175d25adc38d2a5cee134d ]

A lock type of 0 is "LockRead", which makes the fileserver record an
unintentional read lock on the new file.  This will cause problems
later on if the file is the subject of locking operations.

The correct default value should be -1 ("LockNone").

Fix the operation marshalling code to set the value and provide an enum to
symbolise the values whilst we're at it.

Fixes: 30062bd13e36 ("afs: Implement YFS support in the fs client")
Signed-off-by: Marc Dionne 
Signed-off-by: David Howells 
Signed-off-by: Sasha Levin

Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2018-11-30T18:47:50+00:00

Pull vfs fixes from Al Viro:
 "Assorted fixes all over the place.

  The iov_iter one is this cycle regression (splice from UDP triggering
  WARN_ON()), the rest is older"

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  afs: Use d_instantiate() rather than d_add() and don't d_drop()
  afs: Fix missing net error handling
  afs: Fix validation/callback interaction
  iov_iter: teach csum_and_copy_to_iter() to handle pipe-backed ones
  exportfs: do not read dentry after free
  exportfs: fix 'passing zero to ERR_PTR()' warning
  aio: fix failure to put the file pointer
  sysv: return 'err' instead of 0 in __sysv_write_inode

afs: Use d_instantiate() rather than d_add() and don't d_drop()

2018-11-30T02:08:14+00:00

Use d_instantiate() rather than d_add() and don't d_drop() in
afs_vnode_new_inode().  The dentry shouldn't be removed as it's not
changing its name.

Reported-by: Al Viro 
Signed-off-by: David Howells 
Signed-off-by: Al Viro

afs: Fix missing net error handling

2018-11-30T02:08:14+00:00

kAFS can be given certain network errors (EADDRNOTAVAIL, EHOSTDOWN and
ERFKILL) that it doesn't handle in its server/address rotation algorithms.
They cause the probing and rotation to abort immediately rather than
rotating.

Fix this by:

 (1) Abstracting out the error prioritisation from the VL and FS rotation
     algorithms into a common function and expand usage into the server
     probing code.

     When multiple errors are available, this code selects the one we'd
     prefer to return.

 (2) Add handling for EADDRNOTAVAIL, EHOSTDOWN and ERFKILL.

Fixes: 0fafdc9f888b ("afs: Fix file locking")
Fixes: 0338747d8454 ("afs: Probe multiple fileservers simultaneously")
Signed-off-by: David Howells 
Signed-off-by: Al Viro

afs: Fix validation/callback interaction

2018-11-30T02:08:14+00:00

When afs_validate() is called to validate a vnode (inode), there are two
unhandled cases in the fastpath at the top of the function:

 (1) If the vnode is promised (AFS_VNODE_CB_PROMISED is set), the break
     counters match and the data has expired, then there's an implicit case
     in which the vnode needs revalidating.

     This has no consequences since the default "valid = false" set at the
     top of the function happens to do the right thing.

 (2) If the vnode is not promised and it hasn't been deleted
     (AFS_VNODE_DELETED is not set) then there's a default case we're not
     handling in which the vnode is invalid.  If the vnode is invalid, we
     need to bring cb_s_break and cb_v_break up to date before we refetch
     the status.

     As a consequence, once the server loses track of the client
     (ie. sufficient time has passed since we last sent it an operation),
     it will send us a CB.InitCallBackState* operation when we next try to
     talk to it.  This calls afs_init_callback_state() which increments
     afs_server::cb_s_break, but this then doesn't propagate to the
     afs_vnode record.

     The result being that every afs_validate() call thereafter sends a
     status fetch operation to the server.

Clarify and fix this by:

 (A) Setting valid in all the branches rather than initialising it at the
     top so that the compiler catches where we've missed.

 (B) Restructuring the logic in the 'promised' branch so that we set valid
     to false if the callback is due to expire (or has expired) and so that
     the final case is that the vnode is still valid.

 (C) Adding an else-statement that ups cb_s_break and cb_v_break if the
     promised and deleted cases don't match.

Fixes: c435ee34551e ("afs: Overhaul the callback handling")
Signed-off-by: David Howells 
Signed-off-by: Al Viro

rxrpc: Fix life check

2018-11-15T19:35:40+00:00

The life-checking function, which is used by kAFS to make sure that a call
is still live in the event of a pending signal, only samples the received
packet serial number counter; it doesn't actually provoke a change in the
counter, rather relying on the server to happen to give us a packet in the
time window.

Fix this by adding a function to force a ping to be transmitted.

kAFS then keeps track of whether there's been a stall, and if so, uses the
new function to ping the server, resetting the timeout to allow the reply
to come back.

If there's a stall, a ping and the call is *still* stalled in the same
place after another period, then the call will be aborted.

Fixes: bc5e3a546d55 ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Fixes: f4d15fb6f99a ("rxrpc: Provide functions for allowing cleaner handling of signals")
Signed-off-by: David Howells 
Signed-off-by: David S. Miller