[ Upstream commit 65550098c1c4db528400c73acf3e46bfa78d9264 ]
There's a race between rxrpc_sendmsg setting up a call, but then failing to
send anything on it due to an error, and recvmsg() seeing the call
completion occur and trying to return the state to the user.
An assertion fails in rxrpc_recvmsg() because the call has already been
released from the socket and is about to be released again as recvmsg deals
with it. (The recvmsg_q queue on the socket holds a ref, so there's no
problem with use-after-free.)
We also have to be careful not to end up reporting an error twice, in such
a way that both returns indicate to userspace that the user ID supplied
with the call is no longer in use - which could cause the client to
malfunction if it recycles the user ID fast enough.
Fix this by the following means:
(1) When sendmsg() creates a call after the point that the call has been
successfully added to the socket, don't return any errors through
sendmsg(), but rather complete the call and let recvmsg() retrieve
them. Make sendmsg() return 0 at this point. Further calls to
sendmsg() for that call will fail with ESHUTDOWN.
Note that at this point, we haven't send any packets yet, so the
server doesn't yet know about the call.
(2) If sendmsg() returns an error when it was expected to create a new
call, it means that the user ID wasn't used.
(3) Mark the call disconnected before marking it completed to prevent an
oops in rxrpc_release_call().
(4) recvmsg() will then retrieve the error and set MSG_EOR to indicate
that the user ID is no longer known by the kernel.
An oops like the following is produced:
kernel BUG at net/rxrpc/recvmsg.c:605!
...
RIP: 0010:rxrpc_recvmsg+0x256/0x5ae
...
Call Trace:
? __init_waitqueue_head+0x2f/0x2f
____sys_recvmsg+0x8a/0x148
? import_iovec+0x69/0x9c
? copy_msghdr_from_user+0x5c/0x86
___sys_recvmsg+0x72/0xaa
? __fget_files+0x22/0x57
? __fget_light+0x46/0x51
? fdget+0x9/0x1b
do_recvmmsg+0x15e/0x232
? _raw_spin_unlock+0xa/0xb
? vtime_delta+0xf/0x25
__x64_sys_recvmmsg+0x2c/0x2f
do_syscall_64+0x4c/0x78
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: 357f5ef64628 ("rxrpc: Call rxrpc_release_call() on error in rxrpc_new_client_call()")
Reported-by: syzbot+b54969381df354936d96@syzkaller.appspotmail.com
Signed-off-by: David Howells <dhowells@redhat.com>
Reviewed-by: Marc Dionne <marc.dionne@auristor.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit 639f181f0ee20d3249dbc55f740f0167267180f0 ]
rxrpc_sendmsg() returns EPIPE if there's an outstanding error, such as if
rxrpc_recvmsg() indicating ENODATA if there's nothing for it to read.
Change rxrpc_recvmsg() to return EAGAIN instead if there's nothing to read
as this particular error doesn't get stored in ->sk_err by the networking
core.
Also change rxrpc_sendmsg() so that it doesn't fail with delayed receive
errors (there's no way for it to report which call, if any, the error was
caused by).
Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
commit c410bf01933e5e09d142c66c3df9ad470a7eec13 upstream.
rxrpc currently uses a fixed 4s retransmission timeout until the RTT is
sufficiently sampled. This can cause problems with some fileservers with
calls to the cache manager in the afs filesystem being dropped from the
fileserver because a packet goes missing and the retransmission timeout is
greater than the call expiry timeout.
Fix this by:
(1) Copying the RTT/RTO calculation code from Linux's TCP implementation
and altering it to fit rxrpc.
(2) Altering the various users of the RTT to make use of the new SRTT
value.
(3) Replacing the use of rxrpc_resend_timeout to use the calculated RTO
value instead (which is needed in jiffies), along with a backoff.
Notes:
(1) rxrpc provides RTT samples by matching the serial numbers on outgoing
DATA packets that have the RXRPC_REQUEST_ACK set and PING ACK packets
against the reference serial number in incoming REQUESTED ACK and
PING-RESPONSE ACK packets.
(2) Each packet that is transmitted on an rxrpc connection gets a new
per-connection serial number, even for retransmissions, so an ACK can
be cross-referenced to a specific trigger packet. This allows RTT
information to be drawn from retransmitted DATA packets also.
(3) rxrpc maintains the RTT/RTO state on the rxrpc_peer record rather than
on an rxrpc_call because many RPC calls won't live long enough to
generate more than one sample.
(4) The calculated SRTT value is in units of 8ths of a microsecond rather
than nanoseconds.
The (S)RTT and RTO values are displayed in /proc/net/rxrpc/peers.
Fixes: 17926a79320a ([AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both"")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[ Upstream commit e138aa7d3271ac1b0690ae2c9b04d51468dce1d6 ]
Fix the interruptibility of kernel-initiated client calls so that they're
either only interruptible when they're waiting for a call slot to come
available or they're not interruptible at all. Either way, they're not
interruptible during transmission.
This should help prevent StoreData calls from being interrupted when
writeback is in progress. It doesn't, however, handle interruption during
the receive phase.
Userspace-initiated calls are still interruptable. After the signal has
been handled, sendmsg() will return the amount of data copied out of the
buffer and userspace can perform another sendmsg() call to continue
transmission.
Fixes: bc5e3a546d55 ("rxrpc: Use MSG_WAITALL to tell sendmsg() to temporarily ignore signals")
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
[ Upstream commit 158fe6665389964a1de212818b4a5c52b7f7aff4 ]
Abstract out the calculation of there being sufficient Tx buffer space.
This is reproduced several times in the rxrpc sendmsg code.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
David Howells