linux-toradex.git/net/sunrpc, branch v3.4.73

SUNRPC: Fix a data corruption issue when retransmitting RPC calls

2013-11-29T18:50:36+00:00

commit a6b31d18b02ff9d7915c5898c9b5ca41a798cd73 upstream.

The following scenario can cause silent data corruption when doing
NFS writes. It has mainly been observed when doing database writes
using O_DIRECT.

1) The RPC client uses sendpage() to do zero-copy of the page data.
2) Due to networking issues, the reply from the server is delayed,
   and so the RPC client times out.

3) The client issues a second sendpage of the page data as part of
   an RPC call retransmission.

4) The reply to the first transmission arrives from the server
   _before_ the client hardware has emptied the TCP socket send
   buffer.
5) After processing the reply, the RPC state machine rules that
   the call to be done, and triggers the completion callbacks.
6) The application notices the RPC call is done, and reuses the
   pages to store something else (e.g. a new write).

7) The client NIC drains the TCP socket send buffer. Since the
   page data has now changed, it reads a corrupted version of the
   initial RPC call, and puts it on the wire.

This patch fixes the problem in the following manner:

The ordering guarantees of TCP ensure that when the server sends a
reply, then we know that the _first_ transmission has completed. Using
zero-copy in that situation is therefore safe.
If a time out occurs, we then send the retransmission using sendmsg()
(i.e. no zero-copy), We then know that the socket contains a full copy of
the data, and so it will retransmit a faithful reproduction even if the
RPC call completes, and the application reuses the O_DIRECT buffer in
the meantime.

Signed-off-by: Trond Myklebust 
Signed-off-by: Greg Kroah-Hartman

SUNRPC: don't map EKEYEXPIRED to EACCES in call_refreshresult

2013-11-29T18:50:33+00:00

commit f1ff0c27fd9987c59d707cd1a6b6c1fc3ae0a250 upstream.

The NFS layer needs to know when a key has expired.
This change also returns -EKEYEXPIRED to the application, and the informative
"Key has expired" error message is displayed. The user then knows that
credential renewal is required.

Signed-off-by: Andy Adamson 
Signed-off-by: Trond Myklebust 
Signed-off-by: Greg Kroah-Hartman

SUNRPC handle EKEYEXPIRED in call_refreshresult

2013-11-29T18:50:32+00:00

commit eb96d5c97b0825d542e9c4ba5e0a22b519355166 upstream.

Currently, when an RPCSEC_GSS context has expired or is non-existent
and the users (Kerberos) credentials have also expired or are non-existent,
the client receives the -EKEYEXPIRED error and tries to refresh the context
forever.  If an application is performing I/O, or other work against the share,
the application hangs, and the user is not prompted to refresh/establish their
credentials. This can result in a denial of service for other users.

Users are expected to manage their Kerberos credential lifetimes to mitigate
this issue.

Move the -EKEYEXPIRED handling into the RPC layer. Try tk_cred_retry number
of times to refresh the gss_context, and then return -EACCES to the application.

Signed-off-by: Andy Adamson 
Signed-off-by: Trond Myklebust 
[bwh: Backported to 3.2:
 - Adjust context
 - Drop change to nfs4_handle_reclaim_lease_error()]
Signed-off-by: Ben Hutchings 
Signed-off-by: Greg Kroah-Hartman

SUNRPC: Fix memory corruption issue on 32-bit highmem systems

2013-09-08T04:58:15+00:00

commit 347e2233b7667e336d9f671f1a52dfa3f0416e2c upstream.

Some architectures, such as ARM-32 do not return the same base address
when you call kmap_atomic() twice on the same page.
This causes problems for the memmove() call in the XDR helper routine
"_shift_data_right_pages()", since it defeats the detection of
overlapping memory ranges, and has been seen to corrupt memory.

The fix is to distinguish between the case where we're doing an
inter-page copy or not. In the former case of we know that the memory
ranges cannot possibly overlap, so we can additionally micro-optimise
by replacing memmove() with memcpy().

Reported-by: Mark Young 
Reported-by: Matt Craighead 
Cc: Bruce Fields 
Signed-off-by: Trond Myklebust 
Tested-by: Matt Craighead 
Signed-off-by: Greg Kroah-Hartman

SUNRPC: Add barriers to ensure read ordering in rpc_wake_up_task_queue_locked

2013-04-05T17:04:14+00:00

commit 1166fde6a923c30f4351515b6a9a1efc513e7d00 upstream.

We need to be careful when testing task->tk_waitqueue in
rpc_wake_up_task_queue_locked, because it can be changed while we
are holding the queue->lock.
By adding appropriate memory barriers, we can ensure that it is safe to
test task->tk_waitqueue for equality if the RPC_TASK_QUEUED bit is set.

Signed-off-by: Trond Myklebust 
Signed-off-by: Greg Kroah-Hartman

SUNRPC: Don't start the retransmission timer when out of socket space

2013-03-14T18:29:42+00:00

commit a9a6b52ee1baa865283a91eb8d443ee91adfca56 upstream.

If the socket is full, we're better off just waiting until it empties,
or until the connection is broken. The reason why we generally don't
want to time out is that the call to xprt->ops->release_xprt() will
trigger a connection reset, which isn't helpful...

Let's make an exception for soft RPC calls, since they have to provide
timeout guarantees.

Signed-off-by: Trond Myklebust 
Signed-off-by: Greg Kroah-Hartman

svcrpc: make svc_age_temp_xprts enqueue under sv_lock

2013-03-03T22:06:43+00:00

commit e75bafbff2270993926abcc31358361db74a9bc2 upstream.

svc_age_temp_xprts expires xprts in a two-step process: first it takes
the sv_lock and moves the xprts to expire off their server-wide list
(sv_tempsocks or sv_permsocks) to a local list.  Then it drops the
sv_lock and enqueues and puts each one.

I see no reason for this: svc_xprt_enqueue() will take sp_lock, but the
sv_lock and sp_lock are not otherwise nested anywhere (and documentation
at the top of this file claims it's correct to nest these with sp_lock
inside.)

Tested-by: Jason Tibbitts 
Tested-by: Paweł Sikora 
Signed-off-by: J. Bruce Fields 
Signed-off-by: Greg Kroah-Hartman

SUNRPC: Fix validity issues with rpc_pipefs sb->s_fs_info

2013-01-17T16:50:50+00:00

commit 642fe4d00db56d65060ce2fd4c105884414acb16 upstream.

rpc_kill_sb() must defer calling put_net() until after the notifier
has been called, since most (all?) of the notifier callbacks assume
that sb->s_fs_info points to a valid net namespace. It also must not
call put_net() if the call to rpc_fill_super was unsuccessful.

Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=48421

Signed-off-by: Trond Myklebust 
Cc: Stanislav Kinsbursky 
Signed-off-by: Greg Kroah-Hartman

SUNRPC: Ensure we release the socket write lock if the rpc_task exits early

2013-01-17T16:50:46+00:00

commit 87ed50036b866db2ec2ba16b2a7aec4a2b0b7c39 upstream.

If the rpc_task exits while holding the socket write lock before it has
allocated an rpc slot, then the usual mechanism for releasing the write
lock in xprt_release() is defeated.

The problem occurs if the call to xprt_lock_write() initially fails, so
that the rpc_task is put on the xprt->sending wait queue. If the task
exits after being assigned the lock by __xprt_lock_write_func, but
before it has retried the call to xprt_lock_and_alloc_slot(), then
it calls xprt_release() while holding the write lock, but will
immediately exit due to the test for task->tk_rqstp != NULL.

Reported-by: Chris Perl 
Signed-off-by: Trond Myklebust 
Signed-off-by: Greg Kroah-Hartman

SUNRPC: Ensure that we free the rpc_task after cleanups are done

2013-01-17T16:50:46+00:00

commit c6567ed1402c55e19b012e66a8398baec2a726f3 upstream.

This patch ensures that we free the rpc_task after the cleanup callbacks
are done in order to avoid a deadlock problem that can be triggered if
the callback needs to wait for another workqueue item to complete.

Signed-off-by: Trond Myklebust 
Cc: Weston Andros Adamson 
Cc: Tejun Heo 
Cc: Bruce Fields 
Signed-off-by: Greg Kroah-Hartman