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mptcp: handle correctly disconnect() failures

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Currently the mptcp code has assumes that disconnect() can fail only
at mptcp_sendmsg_fastopen() time - to avoid a deadlock scenario - and
don't even bother returning an error code.

Soon mptcp_disconnect() will handle more error conditions: let's track
them explicitly.

As a bonus, explicitly annotate TCP-level disconnect as not failing:
the mptcp code never blocks for event on the subflows.

Fixes: 7d803344fd ("mptcp: fix deadlock in fastopen error path")
Cc: stable@vger.kernel.org
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Tested-by: Christoph Paasch <cpaasch@apple.com>
Reviewed-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Paolo Abeni 2023-06-20 18:24:18 +02:00 committed by Jakub Kicinski
parent 59bb14bda2
commit c2b2ae3925
1 changed files with 14 additions and 6 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

20
net/mptcp/protocol.c
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@ -1727,7 +1727,13 @@ static int mptcp_sendmsg_fastopen(struct sock *sk, struct msghdr *msg,
if (ret && ret != -EINPROGRESS && ret != -ERESTARTSYS && ret != -EINTR) if (ret && ret != -EINPROGRESS && ret != -ERESTARTSYS && ret != -EINTR)
*copied_syn = 0; *copied_syn = 0;
} else if (ret && ret != -EINPROGRESS) { } else if (ret && ret != -EINPROGRESS) {
mptcp_disconnect(sk, 0); /* The disconnect() op called by tcp_sendmsg_fastopen()/
* __inet_stream_connect() can fail, due to looking check,
* see mptcp_disconnect().
* Attempt it again outside the problematic scope.
*/
if (!mptcp_disconnect(sk, 0))
sk->sk_socket->state = SS_UNCONNECTED;
} }
inet_sk(sk)->defer_connect = 0; inet_sk(sk)->defer_connect = 0;
@ -2389,7 +2395,10 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
need_push = (flags & MPTCP_CF_PUSH) && __mptcp_retransmit_pending_data(sk); need_push = (flags & MPTCP_CF_PUSH) && __mptcp_retransmit_pending_data(sk);
if (!dispose_it) { if (!dispose_it) {
tcp_disconnect(ssk, 0); /* The MPTCP code never wait on the subflow sockets, TCP-level
* disconnect should never fail
*/
WARN_ON_ONCE(tcp_disconnect(ssk, 0));
msk->subflow->state = SS_UNCONNECTED; msk->subflow->state = SS_UNCONNECTED;
mptcp_subflow_ctx_reset(subflow); mptcp_subflow_ctx_reset(subflow);
release_sock(ssk); release_sock(ssk);
@ -2812,7 +2821,7 @@ void mptcp_subflow_shutdown(struct sock *sk, struct sock *ssk, int how)
break; break;
fallthrough; fallthrough;
case TCP_SYN_SENT: case TCP_SYN_SENT:
tcp_disconnect(ssk, O_NONBLOCK); WARN_ON_ONCE(tcp_disconnect(ssk, O_NONBLOCK));
break; break;
default: default:
if (__mptcp_check_fallback(mptcp_sk(sk))) { if (__mptcp_check_fallback(mptcp_sk(sk))) {
@ -3075,11 +3084,10 @@ static int mptcp_disconnect(struct sock *sk, int flags)
/* We are on the fastopen error path. We can't call straight into the /* We are on the fastopen error path. We can't call straight into the
* subflows cleanup code due to lock nesting (we are already under * subflows cleanup code due to lock nesting (we are already under
* msk->firstsocket lock). Do nothing and leave the cleanup to the * msk->firstsocket lock).
* caller.
*/ */
if (msk->fastopening) if (msk->fastopening)
return 0; return -EBUSY;
mptcp_listen_inuse_dec(sk); mptcp_listen_inuse_dec(sk);
inet_sk_state_store(sk, TCP_CLOSE); inet_sk_state_store(sk, TCP_CLOSE);