From 41be81a8d3d09acb9033799938306349328861f9 Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Fri, 29 May 2020 17:43:29 +0200 Subject: [PATCH] mptcp: fix unblocking connect() Currently unblocking connect() on MPTCP sockets fails frequently. If mptcp_stream_connect() is invoked to complete a previously attempted unblocking connection, it will still try to create the first subflow via __mptcp_socket_create(). If the 3whs is completed and the 'can_ack' flag is already set, the latter will fail with -EINVAL. This change addresses the issue checking for pending connect and delegating the completion to the first subflow. Additionally do msk addresses and sk_state changes only when needed. Fixes: 2303f994b3e1 ("mptcp: Associate MPTCP context with TCP socket") Signed-off-by: Paolo Abeni Reviewed-by: Mat Martineau Signed-off-by: David S. Miller --- net/mptcp/protocol.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-) diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c index c8675d2..8959a74 100644 --- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -1712,6 +1712,14 @@ static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr, int err; lock_sock(sock->sk); + if (sock->state != SS_UNCONNECTED && msk->subflow) { + /* pending connection or invalid state, let existing subflow + * cope with that + */ + ssock = msk->subflow; + goto do_connect; + } + ssock = __mptcp_socket_create(msk, TCP_SYN_SENT); if (IS_ERR(ssock)) { err = PTR_ERR(ssock); @@ -1726,9 +1734,17 @@ static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr, mptcp_subflow_ctx(ssock->sk)->request_mptcp = 0; #endif +do_connect: err = ssock->ops->connect(ssock, uaddr, addr_len, flags); - inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk)); - mptcp_copy_inaddrs(sock->sk, ssock->sk); + sock->state = ssock->state; + + /* on successful connect, the msk state will be moved to established by + * subflow_finish_connect() + */ + if (!err || err == EINPROGRESS) + mptcp_copy_inaddrs(sock->sk, ssock->sk); + else + inet_sk_state_store(sock->sk, inet_sk_state_load(ssock->sk)); unlock: release_sock(sock->sk); -- 2.7.4