mptcp: avoid unneeded mptcp_token_destroy() calls

The MPTCP protocol currently clears the msk token both at connect() and
listen() time. That is needed to deal with failing connect() calls that
can create a new token while leaving the sk in TCP_CLOSE,SS_UNCONNECTED
status and thus allowing later connect() and/or listen() calls.

Let's deal with such failures explicitly, cleaning the token in a timely
manner and avoid the confusing early mptcp_token_destroy().

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Reviewed-by: Mat Martineau <martineau@kernel.org>
Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 48e649f..abb3105 100644 (file)
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -3594,7 +3594,6 @@ static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
        if (IS_ERR(ssock))
                return PTR_ERR(ssock);
 
-       mptcp_token_destroy(msk);
        inet_sk_state_store(sk, TCP_SYN_SENT);
        subflow = mptcp_subflow_ctx(ssock->sk);
 #ifdef CONFIG_TCP_MD5SIG
@@ -3624,6 +3623,8 @@ static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
         * subflow_finish_connect()
         */
        if (unlikely(err && err != -EINPROGRESS)) {
+               /* avoid leaving a dangling token in an unconnected socket */
+               mptcp_token_destroy(msk);
                inet_sk_state_store(sk, inet_sk_state_load(ssock->sk));
                return err;
        }
@@ -3713,7 +3714,6 @@ static int mptcp_listen(struct socket *sock, int backlog)
                goto unlock;
        }
 
-       mptcp_token_destroy(msk);
        inet_sk_state_store(sk, TCP_LISTEN);
        sock_set_flag(sk, SOCK_RCU_FREE);