[PATCH net-next 01/14] mptcp: avoid unneeded mptcp_token_destroy() calls

Matthieu Baerts
2023-08-11T15:58:46Z

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>
---
net/mptcp/protocol.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index 48e649fe2360..abb310548c37 100644
--- 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);

--
2.40.1