1 files changed, 214 insertions, 116 deletions

diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index f8897a70c11d..1dbc62537259 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -662,9 +662,9 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
 
 		skb = skb_peek(&ssk->sk_receive_queue);
 		if (!skb) {
-			/* if no data is found, a racing workqueue/recvmsg
-			 * already processed the new data, stop here or we
-			 * can enter an infinite loop
+			/* With racing move_skbs_to_msk() and __mptcp_move_skbs(),
+			 * a different CPU can have already processed the pending
+			 * data, stop here or we can enter an infinite loop
 			 */
 			if (!moved)
 				done = true;
@@ -672,9 +672,9 @@ static bool __mptcp_move_skbs_from_subflow(struct mptcp_sock *msk,
 		}
 
 		if (__mptcp_check_fallback(msk)) {
-			/* if we are running under the workqueue, TCP could have
-			 * collapsed skbs between dummy map creation and now
-			 * be sure to adjust the size
+			/* Under fallback skbs have no MPTCP extension and TCP could
+			 * collapse them between the dummy map creation and the
+			 * current dequeue. Be sure to adjust the map size.
 			 */
 			map_remaining = skb->len;
 			subflow->map_data_len = skb->len;
@@ -1544,8 +1544,9 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags)
 	struct mptcp_sendmsg_info info = {
 				.flags = flags,
 	};
+	bool do_check_data_fin = false;
 	struct mptcp_data_frag *dfrag;
-	int len, copied = 0;
+	int len;
 
 	while ((dfrag = mptcp_send_head(sk))) {
 		info.sent = dfrag->already_sent;
@@ -1580,8 +1581,8 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags)
 				goto out;
 			}
 
+			do_check_data_fin = true;
 			info.sent += ret;
-			copied += ret;
 			len -= ret;
 
 			mptcp_update_post_push(msk, dfrag, ret);
@@ -1597,7 +1598,7 @@ out:
 	/* ensure the rtx timer is running */
 	if (!mptcp_timer_pending(sk))
 		mptcp_reset_timer(sk);
-	if (copied)
+	if (do_check_data_fin)
 		__mptcp_check_send_data_fin(sk);
 }
 
@@ -1672,10 +1673,42 @@ static void mptcp_set_nospace(struct sock *sk)
 	set_bit(MPTCP_NOSPACE, &mptcp_sk(sk)->flags);
 }
 
+static int mptcp_sendmsg_fastopen(struct sock *sk, struct sock *ssk, struct msghdr *msg,
+				  size_t len, int *copied_syn)
+{
+	unsigned int saved_flags = msg->msg_flags;
+	struct mptcp_sock *msk = mptcp_sk(sk);
+	int ret;
+
+	lock_sock(ssk);
+	msg->msg_flags |= MSG_DONTWAIT;
+	msk->connect_flags = O_NONBLOCK;
+	msk->is_sendmsg = 1;
+	ret = tcp_sendmsg_fastopen(ssk, msg, copied_syn, len, NULL);
+	msk->is_sendmsg = 0;
+	msg->msg_flags = saved_flags;
+	release_sock(ssk);
+
+	/* do the blocking bits of inet_stream_connect outside the ssk socket lock */
+	if (ret == -EINPROGRESS && !(msg->msg_flags & MSG_DONTWAIT)) {
+		ret = __inet_stream_connect(sk->sk_socket, msg->msg_name,
+					    msg->msg_namelen, msg->msg_flags, 1);
+
+		/* Keep the same behaviour of plain TCP: zero the copied bytes in
+		 * case of any error, except timeout or signal
+		 */
+		if (ret && ret != -EINPROGRESS && ret != -ERESTARTSYS && ret != -EINTR)
+			*copied_syn = 0;
+	}
+
+	return ret;
+}
+
 static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
 	struct page_frag *pfrag;
+	struct socket *ssock;
 	size_t copied = 0;
 	int ret = 0;
 	long timeo;
@@ -1689,14 +1722,30 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 
 	lock_sock(sk);
 
+	ssock = __mptcp_nmpc_socket(msk);
+	if (unlikely(ssock && inet_sk(ssock->sk)->defer_connect)) {
+		int copied_syn = 0;
+
+		ret = mptcp_sendmsg_fastopen(sk, ssock->sk, msg, len, &copied_syn);
+		copied += copied_syn;
+		if (ret == -EINPROGRESS && copied_syn > 0)
+			goto out;
+		else if (ret)
+			goto do_error;
+	}
+
 	timeo = sock_sndtimeo(sk, msg->msg_flags & MSG_DONTWAIT);
 
 	if ((1 << sk->sk_state) & ~(TCPF_ESTABLISHED | TCPF_CLOSE_WAIT)) {
 		ret = sk_stream_wait_connect(sk, &timeo);
 		if (ret)
-			goto out;
+			goto do_error;
 	}
 
+	ret = -EPIPE;
+	if (unlikely(sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)))
+		goto do_error;
+
 	pfrag = sk_page_frag(sk);
 
 	while (msg_data_left(msg)) {
@@ -1705,11 +1754,6 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		bool dfrag_collapsed;
 		size_t psize, offset;
 
-		if (sk->sk_err || (sk->sk_shutdown & SEND_SHUTDOWN)) {
-			ret = -EPIPE;
-			goto out;
-		}
-
 		/* reuse tail pfrag, if possible, or carve a new one from the
 		 * page allocator
 		 */
@@ -1741,7 +1785,7 @@ static int mptcp_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
 		if (copy_page_from_iter(dfrag->page, offset, psize,
 					&msg->msg_iter) != psize) {
 			ret = -EFAULT;
-			goto out;
+			goto do_error;
 		}
 
 		/* data successfully copied into the write queue */
@@ -1773,7 +1817,7 @@ wait_for_memory:
 		__mptcp_push_pending(sk, msg->msg_flags);
 		ret = sk_stream_wait_memory(sk, &timeo);
 		if (ret)
-			goto out;
+			goto do_error;
 	}
 
 	if (copied)
@@ -1781,7 +1825,14 @@ wait_for_memory:
 
 out:
 	release_sock(sk);
-	return copied ? : ret;
+	return copied;
+
+do_error:
+	if (copied)
+		goto out;
+
+	copied = sk_stream_error(sk, msg->msg_flags, ret);
+	goto out;
 }
 
 static int __mptcp_recvmsg_mskq(struct mptcp_sock *msk,
@@ -2284,8 +2335,14 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 
 	lock_sock_nested(ssk, SINGLE_DEPTH_NESTING);
 
-	if (flags & MPTCP_CF_FASTCLOSE)
+	if (flags & MPTCP_CF_FASTCLOSE) {
+		/* be sure to force the tcp_disconnect() path,
+		 * to generate the egress reset
+		 */
+		ssk->sk_lingertime = 0;
+		sock_set_flag(ssk, SOCK_LINGER);
 		subflow->send_fastclose = 1;
+	}
 
 	need_push = (flags & MPTCP_CF_PUSH) && __mptcp_retransmit_pending_data(sk);
 	if (!dispose_it) {
@@ -2297,12 +2354,7 @@ static void __mptcp_close_ssk(struct sock *sk, struct sock *ssk,
 		goto out;
 	}
 
-	/* if we are invoked by the msk cleanup code, the subflow is
-	 * already orphaned
-	 */
-	if (ssk->sk_socket)
-		sock_orphan(ssk);
-
+	sock_orphan(ssk);
 	subflow->disposable = 1;
 
 	/* if ssk hit tcp_done(), tcp_cleanup_ulp() cleared the related ops
@@ -2363,7 +2415,7 @@ static void __mptcp_close_subflow(struct mptcp_sock *msk)
 
 	might_sleep();
 
-	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
+	mptcp_for_each_subflow_safe(msk, subflow, tmp) {
 		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
 
 		if (inet_sk_state_load(ssk) != TCP_CLOSE)
@@ -2406,7 +2458,7 @@ static void mptcp_check_fastclose(struct mptcp_sock *msk)
 
 	mptcp_token_destroy(msk);
 
-	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
+	mptcp_for_each_subflow_safe(msk, subflow, tmp) {
 		struct sock *tcp_sk = mptcp_subflow_tcp_sock(subflow);
 		bool slow;
 
@@ -2418,12 +2470,31 @@ static void mptcp_check_fastclose(struct mptcp_sock *msk)
 		unlock_sock_fast(tcp_sk, slow);
 	}
 
+	/* Mirror the tcp_reset() error propagation */
+	switch (sk->sk_state) {
+	case TCP_SYN_SENT:
+		sk->sk_err = ECONNREFUSED;
+		break;
+	case TCP_CLOSE_WAIT:
+		sk->sk_err = EPIPE;
+		break;
+	case TCP_CLOSE:
+		return;
+	default:
+		sk->sk_err = ECONNRESET;
+	}
+
 	inet_sk_state_store(sk, TCP_CLOSE);
 	sk->sk_shutdown = SHUTDOWN_MASK;
 	smp_mb__before_atomic(); /* SHUTDOWN must be visible first */
 	set_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags);
 
-	mptcp_close_wake_up(sk);
+	/* the calling mptcp_worker will properly destroy the socket */
+	if (sock_flag(sk, SOCK_DEAD))
+		return;
+
+	sk->sk_state_change(sk);
+	sk_error_report(sk);
 }
 
 static void __mptcp_retrans(struct sock *sk)
@@ -2529,6 +2600,16 @@ static void mptcp_mp_fail_no_response(struct mptcp_sock *msk)
 	mptcp_reset_timeout(msk, 0);
 }
 
+static void mptcp_do_fastclose(struct sock *sk)
+{
+	struct mptcp_subflow_context *subflow, *tmp;
+	struct mptcp_sock *msk = mptcp_sk(sk);
+
+	mptcp_for_each_subflow_safe(msk, subflow, tmp)
+		__mptcp_close_ssk(sk, mptcp_subflow_tcp_sock(subflow),
+				  subflow, MPTCP_CF_FASTCLOSE);
+}
+
 static void mptcp_worker(struct work_struct *work)
 {
 	struct mptcp_sock *msk = container_of(work, struct mptcp_sock, work);
@@ -2557,11 +2638,15 @@ static void mptcp_worker(struct work_struct *work)
 	 * closed, but we need the msk around to reply to incoming DATA_FIN,
 	 * even if it is orphaned and in FIN_WAIT2 state
 	 */
-	if (sock_flag(sk, SOCK_DEAD) &&
-	    (mptcp_check_close_timeout(sk) || sk->sk_state == TCP_CLOSE)) {
-		inet_sk_state_store(sk, TCP_CLOSE);
-		__mptcp_destroy_sock(sk);
-		goto unlock;
+	if (sock_flag(sk, SOCK_DEAD)) {
+		if (mptcp_check_close_timeout(sk)) {
+			inet_sk_state_store(sk, TCP_CLOSE);
+			mptcp_do_fastclose(sk);
+		}
+		if (sk->sk_state == TCP_CLOSE) {
+			__mptcp_destroy_sock(sk);
+			goto unlock;
+		}
 	}
 
 	if (test_and_clear_bit(MPTCP_WORK_CLOSE_SUBFLOW, &msk->flags))
@@ -2802,6 +2887,18 @@ static void __mptcp_destroy_sock(struct sock *sk)
 	sock_put(sk);
 }
 
+static __poll_t mptcp_check_readable(struct mptcp_sock *msk)
+{
+	/* Concurrent splices from sk_receive_queue into receive_queue will
+	 * always show at least one non-empty queue when checked in this order.
+	 */
+	if (skb_queue_empty_lockless(&((struct sock *)msk)->sk_receive_queue) &&
+	    skb_queue_empty_lockless(&msk->receive_queue))
+		return 0;
+
+	return EPOLLIN | EPOLLRDNORM;
+}
+
 bool __mptcp_close(struct sock *sk, long timeout)
 {
 	struct mptcp_subflow_context *subflow;
@@ -2815,8 +2912,13 @@ bool __mptcp_close(struct sock *sk, long timeout)
 		goto cleanup;
 	}
 
-	if (mptcp_close_state(sk))
+	if (mptcp_check_readable(msk)) {
+		/* the msk has read data, do the MPTCP equivalent of TCP reset */
+		inet_sk_state_store(sk, TCP_CLOSE);
+		mptcp_do_fastclose(sk);
+	} else if (mptcp_close_state(sk)) {
 		__mptcp_wr_shutdown(sk);
+	}
 
 	sk_stream_wait_close(sk, timeout);
 
@@ -2833,7 +2935,11 @@ cleanup:
 		if (ssk == msk->first)
 			subflow->fail_tout = 0;
 
-		sock_orphan(ssk);
+		/* detach from the parent socket, but allow data_ready to
+		 * push incoming data into the mptcp stack, to properly ack it
+		 */
+		ssk->sk_socket = NULL;
+		ssk->sk_wq = NULL;
 		unlock_sock_fast(ssk, slow);
 	}
 	sock_orphan(sk);
@@ -2867,7 +2973,7 @@ static void mptcp_close(struct sock *sk, long timeout)
 	sock_put(sk);
 }
 
-static void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk)
+void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk)
 {
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
 	const struct ipv6_pinfo *ssk6 = inet6_sk(ssk);
@@ -3063,7 +3169,7 @@ void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags)
 	__mptcp_clear_xmit(sk);
 
 	/* join list will be eventually flushed (with rst) at sock lock release time */
-	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node)
+	mptcp_for_each_subflow_safe(msk, subflow, tmp)
 		__mptcp_close_ssk(sk, mptcp_subflow_tcp_sock(subflow), subflow, flags);
 
 	/* move to sk_receive_queue, sk_stream_kill_queues will purge it */
@@ -3422,10 +3528,73 @@ static int mptcp_ioctl(struct sock *sk, int cmd, unsigned long arg)
 	return put_user(answ, (int __user *)arg);
 }
 
+static void mptcp_subflow_early_fallback(struct mptcp_sock *msk,
+					 struct mptcp_subflow_context *subflow)
+{
+	subflow->request_mptcp = 0;
+	__mptcp_do_fallback(msk);
+}
+
+static int mptcp_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
+{
+	struct mptcp_subflow_context *subflow;
+	struct mptcp_sock *msk = mptcp_sk(sk);
+	struct socket *ssock;
+	int err = -EINVAL;
+
+	ssock = __mptcp_nmpc_socket(msk);
+	if (!ssock)
+		return -EINVAL;
+
+	mptcp_token_destroy(msk);
+	inet_sk_state_store(sk, TCP_SYN_SENT);
+	subflow = mptcp_subflow_ctx(ssock->sk);
+#ifdef CONFIG_TCP_MD5SIG
+	/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
+	 * TCP option space.
+	 */
+	if (rcu_access_pointer(tcp_sk(ssock->sk)->md5sig_info))
+		mptcp_subflow_early_fallback(msk, subflow);
+#endif
+	if (subflow->request_mptcp && mptcp_token_new_connect(ssock->sk)) {
+		MPTCP_INC_STATS(sock_net(ssock->sk), MPTCP_MIB_TOKENFALLBACKINIT);
+		mptcp_subflow_early_fallback(msk, subflow);
+	}
+	if (likely(!__mptcp_check_fallback(msk)))
+		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVE);
+
+	/* if reaching here via the fastopen/sendmsg path, the caller already
+	 * acquired the subflow socket lock, too.
+	 */
+	if (msk->is_sendmsg)
+		err = __inet_stream_connect(ssock, uaddr, addr_len, msk->connect_flags, 1);
+	else
+		err = inet_stream_connect(ssock, uaddr, addr_len, msk->connect_flags);
+	inet_sk(sk)->defer_connect = inet_sk(ssock->sk)->defer_connect;
+
+	/* on successful connect, the msk state will be moved to established by
+	 * subflow_finish_connect()
+	 */
+	if (unlikely(err && err != -EINPROGRESS)) {
+		inet_sk_state_store(sk, inet_sk_state_load(ssock->sk));
+		return err;
+	}
+
+	mptcp_copy_inaddrs(sk, ssock->sk);
+
+	/* unblocking connect, mptcp-level inet_stream_connect will error out
+	 * without changing the socket state, update it here.
+	 */
+	if (err == -EINPROGRESS)
+		sk->sk_socket->state = ssock->state;
+	return err;
+}
+
 static struct proto mptcp_prot = {
 	.name		= "MPTCP",
 	.owner		= THIS_MODULE,
 	.init		= mptcp_init_sock,
+	.connect	= mptcp_connect,
 	.disconnect	= mptcp_disconnect,
 	.close		= mptcp_close,
 	.accept		= mptcp_accept,
@@ -3477,77 +3646,16 @@ unlock:
 	return err;
 }
 
-static void mptcp_subflow_early_fallback(struct mptcp_sock *msk,
-					 struct mptcp_subflow_context *subflow)
-{
-	subflow->request_mptcp = 0;
-	__mptcp_do_fallback(msk);
-}
-
 static int mptcp_stream_connect(struct socket *sock, struct sockaddr *uaddr,
 				int addr_len, int flags)
 {
-	struct mptcp_sock *msk = mptcp_sk(sock->sk);
-	struct mptcp_subflow_context *subflow;
-	struct socket *ssock;
-	int err = -EINVAL;
+	int ret;
 
 	lock_sock(sock->sk);
-	if (uaddr) {
-		if (addr_len < sizeof(uaddr->sa_family))
-			goto unlock;
-
-		if (uaddr->sa_family == AF_UNSPEC) {
-			err = mptcp_disconnect(sock->sk, flags);
-			sock->state = err ? SS_DISCONNECTING : SS_UNCONNECTED;
-			goto unlock;
-		}
-	}
-
-	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_nmpc_socket(msk);
-	if (!ssock)
-		goto unlock;
-
-	mptcp_token_destroy(msk);
-	inet_sk_state_store(sock->sk, TCP_SYN_SENT);
-	subflow = mptcp_subflow_ctx(ssock->sk);
-#ifdef CONFIG_TCP_MD5SIG
-	/* no MPTCP if MD5SIG is enabled on this socket or we may run out of
-	 * TCP option space.
-	 */
-	if (rcu_access_pointer(tcp_sk(ssock->sk)->md5sig_info))
-		mptcp_subflow_early_fallback(msk, subflow);
-#endif
-	if (subflow->request_mptcp && mptcp_token_new_connect(ssock->sk)) {
-		MPTCP_INC_STATS(sock_net(ssock->sk), MPTCP_MIB_TOKENFALLBACKINIT);
-		mptcp_subflow_early_fallback(msk, subflow);
-	}
-	if (likely(!__mptcp_check_fallback(msk)))
-		MPTCP_INC_STATS(sock_net(sock->sk), MPTCP_MIB_MPCAPABLEACTIVE);
-
-do_connect:
-	err = ssock->ops->connect(ssock, uaddr, addr_len, flags);
-	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:
+	mptcp_sk(sock->sk)->connect_flags = flags;
+	ret = __inet_stream_connect(sock, uaddr, addr_len, flags, 0);
 	release_sock(sock->sk);
-	return err;
+	return ret;
 }
 
 static int mptcp_listen(struct socket *sock, int backlog)
@@ -3613,7 +3721,6 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
 		if (mptcp_is_fully_established(newsk))
 			mptcp_pm_fully_established(msk, msk->first, GFP_KERNEL);
 
-		mptcp_copy_inaddrs(newsk, msk->first);
 		mptcp_rcv_space_init(msk, msk->first);
 		mptcp_propagate_sndbuf(newsk, msk->first);
 
@@ -3632,18 +3739,6 @@ static int mptcp_stream_accept(struct socket *sock, struct socket *newsock,
 	return err;
 }
 
-static __poll_t mptcp_check_readable(struct mptcp_sock *msk)
-{
-	/* Concurrent splices from sk_receive_queue into receive_queue will
-	 * always show at least one non-empty queue when checked in this order.
-	 */
-	if (skb_queue_empty_lockless(&((struct sock *)msk)->sk_receive_queue) &&
-	    skb_queue_empty_lockless(&msk->receive_queue))
-		return 0;
-
-	return EPOLLIN | EPOLLRDNORM;
-}
-
 static __poll_t mptcp_check_writeable(struct mptcp_sock *msk)
 {
 	struct sock *sk = (struct sock *)msk;
@@ -3685,13 +3780,16 @@ static __poll_t mptcp_poll(struct file *file, struct socket *sock,
 	if (state != TCP_SYN_SENT && state != TCP_SYN_RECV) {
 		mask |= mptcp_check_readable(msk);
 		mask |= mptcp_check_writeable(msk);
+	} else if (state == TCP_SYN_SENT && inet_sk(sk)->defer_connect) {
+		/* cf tcp_poll() note about TFO */
+		mask |= EPOLLOUT | EPOLLWRNORM;
 	}
 	if (sk->sk_shutdown == SHUTDOWN_MASK || state == TCP_CLOSE)
 		mask |= EPOLLHUP;
 	if (sk->sk_shutdown & RCV_SHUTDOWN)
 		mask |= EPOLLIN | EPOLLRDNORM | EPOLLRDHUP;
 
-	/* This barrier is coupled with smp_wmb() in tcp_reset() */
+	/* This barrier is coupled with smp_wmb() in __mptcp_error_report() */
 	smp_rmb();
 	if (sk->sk_err)
 		mask |= EPOLLERR;