Merge branch 'mptcp-fixes'

Mat Martineau says:

====================
mptcp: Fixes for mptcp cleanup/close and a selftest

Patch 1 fixes an issue with leaking subflow sockets if there's a failure
in a CGROUP_INET_SOCK_CREATE eBPF program.

Patch 2 fixes a syzkaller-detected race at MPTCP socket close.

Patch 3 is a fix for one mode of the mptcp_connect.sh selftest.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

net/mptcp/protocol.c

@@ -1240,6 +1240,9 @@ static int mptcp_sendmsg_frag(struct sock *sk, struct sock *ssk,
 			 info->limit > dfrag->data_len))
 		return 0;
 
+	if (unlikely(!__tcp_can_send(ssk)))
+		return -EAGAIN;
+
 	/* compute send limit */
 	info->mss_now = tcp_send_mss(ssk, &info->size_goal, info->flags);
 	copy = info->size_goal;
@@ -1413,7 +1416,8 @@ static struct sock *mptcp_subflow_get_send(struct mptcp_sock *msk)
 	if (__mptcp_check_fallback(msk)) {
 		if (!msk->first)
 			return NULL;
-		return sk_stream_memory_free(msk->first) ? msk->first : NULL;
+		return __tcp_can_send(msk->first) &&
+		       sk_stream_memory_free(msk->first) ? msk->first : NULL;
 	}
 
 	/* re-use last subflow, if the burst allow that */
@@ -1564,6 +1568,8 @@ void __mptcp_push_pending(struct sock *sk, unsigned int flags)
 
 			ret = mptcp_sendmsg_frag(sk, ssk, dfrag, &info);
 			if (ret <= 0) {
+				if (ret == -EAGAIN)
+					continue;
 				mptcp_push_release(ssk, &info);
 				goto out;
 			}
@@ -2769,30 +2775,16 @@ static void __mptcp_wr_shutdown(struct sock *sk)
 
 static void __mptcp_destroy_sock(struct sock *sk)
 {
-	struct mptcp_subflow_context *subflow, *tmp;
 	struct mptcp_sock *msk = mptcp_sk(sk);
-	LIST_HEAD(conn_list);
 
 	pr_debug("msk=%p", msk);
 
 	might_sleep();
 
-	/* join list will be eventually flushed (with rst) at sock lock release time*/
-	list_splice_init(&msk->conn_list, &conn_list);
-
 	mptcp_stop_timer(sk);
 	sk_stop_timer(sk, &sk->sk_timer);
 	msk->pm.status = 0;
 
-	/* clears msk->subflow, allowing the following loop to close
-	 * even the initial subflow
-	 */
-	mptcp_dispose_initial_subflow(msk);
-	list_for_each_entry_safe(subflow, tmp, &conn_list, node) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-		__mptcp_close_ssk(sk, ssk, subflow, 0);
-	}
-
 	sk->sk_prot->destroy(sk);
 
 	WARN_ON_ONCE(msk->rmem_fwd_alloc);
@@ -2884,24 +2876,20 @@ static void mptcp_copy_inaddrs(struct sock *msk, const struct sock *ssk)
 
 static int mptcp_disconnect(struct sock *sk, int flags)
 {
-	struct mptcp_subflow_context *subflow, *tmp;
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
 	inet_sk_state_store(sk, TCP_CLOSE);
 
-	list_for_each_entry_safe(subflow, tmp, &msk->conn_list, node) {
-		struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-
-		__mptcp_close_ssk(sk, ssk, subflow, MPTCP_CF_FASTCLOSE);
-	}
-
 	mptcp_stop_timer(sk);
 	sk_stop_timer(sk, &sk->sk_timer);
 
 	if (mptcp_sk(sk)->token)
 		mptcp_event(MPTCP_EVENT_CLOSED, mptcp_sk(sk), NULL, GFP_KERNEL);
 
-	mptcp_destroy_common(msk);
+	/* msk->subflow is still intact, the following will not free the first
+	 * subflow
+	 */
+	mptcp_destroy_common(msk, MPTCP_CF_FASTCLOSE);
 	msk->last_snd = NULL;
 	WRITE_ONCE(msk->flags, 0);
 	msk->cb_flags = 0;
@@ -3051,12 +3039,17 @@ static struct sock *mptcp_accept(struct sock *sk, int flags, int *err,
 	return newsk;
 }
 
-void mptcp_destroy_common(struct mptcp_sock *msk)
+void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags)
 {
+	struct mptcp_subflow_context *subflow, *tmp;
 	struct sock *sk = (struct sock *)msk;
 
 	__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_close_ssk(sk, mptcp_subflow_tcp_sock(subflow), subflow, flags);
+
 	/* move to sk_receive_queue, sk_stream_kill_queues will purge it */
 	mptcp_data_lock(sk);
 	skb_queue_splice_tail_init(&msk->receive_queue, &sk->sk_receive_queue);
@@ -3078,7 +3071,11 @@ static void mptcp_destroy(struct sock *sk)
 {
 	struct mptcp_sock *msk = mptcp_sk(sk);
 
-	mptcp_destroy_common(msk);
+	/* clears msk->subflow, allowing the following to close
+	 * even the initial subflow
+	 */
+	mptcp_dispose_initial_subflow(msk);
+	mptcp_destroy_common(msk, 0);
 	sk_sockets_allocated_dec(sk);
 }
 

net/mptcp/protocol.h

@@ -624,16 +624,19 @@ void mptcp_info2sockaddr(const struct mptcp_addr_info *info,
 			 struct sockaddr_storage *addr,
 			 unsigned short family);
 
+static inline bool __tcp_can_send(const struct sock *ssk)
+{
+	/* only send if our side has not closed yet */
+	return ((1 << inet_sk_state_load(ssk)) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT));
+}
+
 static inline bool __mptcp_subflow_active(struct mptcp_subflow_context *subflow)
 {
-	struct sock *ssk = mptcp_subflow_tcp_sock(subflow);
-
 	/* can't send if JOIN hasn't completed yet (i.e. is usable for mptcp) */
 	if (subflow->request_join && !subflow->fully_established)
 		return false;
 
-	/* only send if our side has not closed yet */
-	return ((1 << ssk->sk_state) & (TCPF_ESTABLISHED | TCPF_CLOSE_WAIT));
+	return __tcp_can_send(mptcp_subflow_tcp_sock(subflow));
 }
 
 void mptcp_subflow_set_active(struct mptcp_subflow_context *subflow);
@@ -717,7 +720,7 @@ static inline void mptcp_write_space(struct sock *sk)
 	}
 }
 
-void mptcp_destroy_common(struct mptcp_sock *msk);
+void mptcp_destroy_common(struct mptcp_sock *msk, unsigned int flags);
 
 #define MPTCP_TOKEN_MAX_RETRIES	4
 

net/mptcp/subflow.c

@@ -621,7 +621,8 @@ static void mptcp_sock_destruct(struct sock *sk)
 		sock_orphan(sk);
 	}
 
-	mptcp_destroy_common(mptcp_sk(sk));
+	/* We don't need to clear msk->subflow, as it's still NULL at this point */
+	mptcp_destroy_common(mptcp_sk(sk), 0);
 	inet_sock_destruct(sk);
 }
 

tools/testing/selftests/net/mptcp/mptcp_connect.c

@@ -553,6 +553,18 @@ static void set_nonblock(int fd, bool nonblock)
 		fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
 }
 
+static void shut_wr(int fd)
+{
+	/* Close our write side, ev. give some time
+	 * for address notification and/or checking
+	 * the current status
+	 */
+	if (cfg_wait)
+		usleep(cfg_wait);
+
+	shutdown(fd, SHUT_WR);
+}
+
 static int copyfd_io_poll(int infd, int peerfd, int outfd, bool *in_closed_after_out)
 {
 	struct pollfd fds = {
@@ -630,14 +642,7 @@ static int copyfd_io_poll(int infd, int peerfd, int outfd, bool *in_closed_after
 					/* ... and peer also closed already */
 					break;
 
-				/* ... but we still receive.
-				 * Close our write side, ev. give some time
-				 * for address notification and/or checking
-				 * the current status
-				 */
-				if (cfg_wait)
-					usleep(cfg_wait);
-				shutdown(peerfd, SHUT_WR);
+				shut_wr(peerfd);
 			} else {
 				if (errno == EINTR)
 					continue;
@@ -767,7 +772,7 @@ static int copyfd_io_mmap(int infd, int peerfd, int outfd,
 		if (err)
 			return err;
 
-		shutdown(peerfd, SHUT_WR);
+		shut_wr(peerfd);
 
 		err = do_recvfile(peerfd, outfd);
 		*in_closed_after_out = true;
@@ -791,6 +796,9 @@ static int copyfd_io_sendfile(int infd, int peerfd, int outfd,
 		err = do_sendfile(infd, peerfd, size);
 		if (err)
 			return err;
+
+		shut_wr(peerfd);
+
 		err = do_recvfile(peerfd, outfd);
 		*in_closed_after_out = true;
 	}