Merge branch 'mptcp-fixes'

Mat Martineau says:

====================
mptcp: Fixes for v5.13

Here are two MPTCP fixes from Paolo.

Patch 1 fixes some possible connect-time race conditions with
MPTCP-level connection state changes.

Patch 2 deletes a duplicate function declaration.
====================
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/mptcp/protocol.c

@@ -2946,6 +2946,11 @@ static void mptcp_release_cb(struct sock *sk)
 		spin_lock_bh(&sk->sk_lock.slock);
 	}
 
+	/* be sure to set the current sk state before tacking actions
+	 * depending on sk_state
+	 */
+	if (test_and_clear_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->flags))
+		__mptcp_set_connected(sk);
 	if (test_and_clear_bit(MPTCP_CLEAN_UNA, &mptcp_sk(sk)->flags))
 		__mptcp_clean_una_wakeup(sk);
 	if (test_and_clear_bit(MPTCP_ERROR_REPORT, &mptcp_sk(sk)->flags))

net/mptcp/protocol.h

@@ -109,6 +109,7 @@
 #define MPTCP_ERROR_REPORT	8
 #define MPTCP_RETRANSMIT	9
 #define MPTCP_WORK_SYNC_SETSOCKOPT 10
+#define MPTCP_CONNECTED		11
 
 static inline bool before64(__u64 seq1, __u64 seq2)
 {
@@ -579,6 +580,7 @@ void mptcp_get_options(const struct sk_buff *skb,
 		       struct mptcp_options_received *mp_opt);
 
 void mptcp_finish_connect(struct sock *sk);
+void __mptcp_set_connected(struct sock *sk);
 static inline bool mptcp_is_fully_established(struct sock *sk)
 {
 	return inet_sk_state_load(sk) == TCP_ESTABLISHED &&
@@ -760,9 +762,6 @@ unsigned int mptcp_pm_get_add_addr_accept_max(struct mptcp_sock *msk);
 unsigned int mptcp_pm_get_subflows_max(struct mptcp_sock *msk);
 unsigned int mptcp_pm_get_local_addr_max(struct mptcp_sock *msk);
 
-int mptcp_setsockopt(struct sock *sk, int level, int optname,
-		     sockptr_t optval, unsigned int optlen);
-
 void mptcp_sockopt_sync(struct mptcp_sock *msk, struct sock *ssk);
 void mptcp_sockopt_sync_all(struct mptcp_sock *msk);
 

net/mptcp/subflow.c

@@ -371,6 +371,24 @@ static bool subflow_use_different_dport(struct mptcp_sock *msk, const struct soc
 	return inet_sk(sk)->inet_dport != inet_sk((struct sock *)msk)->inet_dport;
 }
 
+void __mptcp_set_connected(struct sock *sk)
+{
+	if (sk->sk_state == TCP_SYN_SENT) {
+		inet_sk_state_store(sk, TCP_ESTABLISHED);
+		sk->sk_state_change(sk);
+	}
+}
+
+static void mptcp_set_connected(struct sock *sk)
+{
+	mptcp_data_lock(sk);
+	if (!sock_owned_by_user(sk))
+		__mptcp_set_connected(sk);
+	else
+		set_bit(MPTCP_CONNECTED, &mptcp_sk(sk)->flags);
+	mptcp_data_unlock(sk);
+}
+
 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
@@ -379,10 +397,6 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 
 	subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
 
-	if (inet_sk_state_load(parent) == TCP_SYN_SENT) {
-		inet_sk_state_store(parent, TCP_ESTABLISHED);
-		parent->sk_state_change(parent);
-	}
 
 	/* be sure no special action on any packet other than syn-ack */
 	if (subflow->conn_finished)
@@ -411,6 +425,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 			 subflow->remote_key);
 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
 		mptcp_finish_connect(sk);
+		mptcp_set_connected(parent);
 	} else if (subflow->request_join) {
 		u8 hmac[SHA256_DIGEST_SIZE];
 
@@ -451,6 +466,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 	} else if (mptcp_check_fallback(sk)) {
 fallback:
 		mptcp_rcv_space_init(mptcp_sk(parent), sk);
+		mptcp_set_connected(parent);
 	}
 	return;
 
@@ -558,6 +574,7 @@ static void mptcp_sock_destruct(struct sock *sk)
 
 static void mptcp_force_close(struct sock *sk)
 {
+	/* the msk is not yet exposed to user-space */
 	inet_sk_state_store(sk, TCP_CLOSE);
 	sk_common_release(sk);
 }
@@ -1474,10 +1491,7 @@ static void subflow_state_change(struct sock *sk)
 		mptcp_rcv_space_init(mptcp_sk(parent), sk);
 		pr_fallback(mptcp_sk(parent));
 		subflow->conn_finished = 1;
-		if (inet_sk_state_load(parent) == TCP_SYN_SENT) {
-			inet_sk_state_store(parent, TCP_ESTABLISHED);
-			parent->sk_state_change(parent);
-		}
+		mptcp_set_connected(parent);
 	}
 
 	/* as recvmsg() does not acquire the subflow socket for ssk selection