1 files changed, 35 insertions, 22 deletions

diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c
index f3c336872475..eca4de08ca9c 100644
--- a/net/mptcp/subflow.c
+++ b/net/mptcp/subflow.c
@@ -392,11 +392,33 @@ static void mptcp_set_connected(struct sock *sk)
 	mptcp_data_unlock(sk);
 }
 
+static void subflow_set_remote_key(struct mptcp_sock *msk,
+				   struct mptcp_subflow_context *subflow,
+				   const struct mptcp_options_received *mp_opt)
+{
+	/* active MPC subflow will reach here multiple times:
+	 * at subflow_finish_connect() time and at 4th ack time
+	 */
+	if (subflow->remote_key_valid)
+		return;
+
+	subflow->remote_key_valid = 1;
+	subflow->remote_key = mp_opt->sndr_key;
+	mptcp_crypto_key_sha(subflow->remote_key, NULL, &subflow->iasn);
+	subflow->iasn++;
+
+	WRITE_ONCE(msk->remote_key, subflow->remote_key);
+	WRITE_ONCE(msk->ack_seq, subflow->iasn);
+	WRITE_ONCE(msk->can_ack, true);
+	atomic64_set(&msk->rcv_wnd_sent, subflow->iasn);
+}
+
 static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 {
 	struct mptcp_subflow_context *subflow = mptcp_subflow_ctx(sk);
 	struct mptcp_options_received mp_opt;
 	struct sock *parent = subflow->conn;
+	struct mptcp_sock *msk;
 
 	subflow->icsk_af_ops->sk_rx_dst_set(sk, skb);
 
@@ -404,6 +426,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 	if (subflow->conn_finished)
 		return;
 
+	msk = mptcp_sk(parent);
 	mptcp_propagate_sndbuf(parent, sk);
 	subflow->rel_write_seq = 1;
 	subflow->conn_finished = 1;
@@ -416,19 +439,16 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 			MPTCP_INC_STATS(sock_net(sk),
 					MPTCP_MIB_MPCAPABLEACTIVEFALLBACK);
 			mptcp_do_fallback(sk);
-			pr_fallback(mptcp_sk(subflow->conn));
+			pr_fallback(msk);
 			goto fallback;
 		}
 
 		if (mp_opt.suboptions & OPTION_MPTCP_CSUMREQD)
-			WRITE_ONCE(mptcp_sk(parent)->csum_enabled, true);
+			WRITE_ONCE(msk->csum_enabled, true);
 		if (mp_opt.deny_join_id0)
-			WRITE_ONCE(mptcp_sk(parent)->pm.remote_deny_join_id0, true);
+			WRITE_ONCE(msk->pm.remote_deny_join_id0, true);
 		subflow->mp_capable = 1;
-		subflow->can_ack = 1;
-		subflow->remote_key = mp_opt.sndr_key;
-		pr_debug("subflow=%p, remote_key=%llu", subflow,
-			 subflow->remote_key);
+		subflow_set_remote_key(msk, subflow, &mp_opt);
 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_MPCAPABLEACTIVEACK);
 		mptcp_finish_connect(sk);
 		mptcp_set_connected(parent);
@@ -466,7 +486,7 @@ static void subflow_finish_connect(struct sock *sk, const struct sk_buff *skb)
 		subflow->mp_join = 1;
 		MPTCP_INC_STATS(sock_net(sk), MPTCP_MIB_JOINSYNACKRX);
 
-		if (subflow_use_different_dport(mptcp_sk(parent), sk)) {
+		if (subflow_use_different_dport(msk, sk)) {
 			pr_debug("synack inet_dport=%d %d",
 				 ntohs(inet_sk(sk)->inet_dport),
 				 ntohs(inet_sk(parent)->inet_dport));
@@ -474,7 +494,7 @@ 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_rcv_space_init(msk, sk);
 		mptcp_set_connected(parent);
 	}
 	return;
@@ -637,13 +657,12 @@ static void subflow_drop_ctx(struct sock *ssk)
 }
 
 void mptcp_subflow_fully_established(struct mptcp_subflow_context *subflow,
-				     struct mptcp_options_received *mp_opt)
+				     const struct mptcp_options_received *mp_opt)
 {
 	struct mptcp_sock *msk = mptcp_sk(subflow->conn);
 
-	subflow->remote_key = mp_opt->sndr_key;
+	subflow_set_remote_key(msk, subflow, mp_opt);
 	subflow->fully_established = 1;
-	subflow->can_ack = 1;
 	WRITE_ONCE(msk->fully_established, true);
 }
 
@@ -1198,16 +1217,8 @@ static bool subflow_check_data_avail(struct sock *ssk)
 		if (WARN_ON_ONCE(!skb))
 			goto no_data;
 
-		/* if msk lacks the remote key, this subflow must provide an
-		 * MP_CAPABLE-based mapping
-		 */
-		if (unlikely(!READ_ONCE(msk->can_ack))) {
-			if (!subflow->mpc_map)
-				goto fallback;
-			WRITE_ONCE(msk->remote_key, subflow->remote_key);
-			WRITE_ONCE(msk->ack_seq, subflow->map_seq);
-			WRITE_ONCE(msk->can_ack, true);
-		}
+		if (unlikely(!READ_ONCE(msk->can_ack)))
+			goto fallback;
 
 		old_ack = READ_ONCE(msk->ack_seq);
 		ack_seq = mptcp_subflow_get_mapped_dsn(subflow);
@@ -1480,6 +1491,7 @@ int __mptcp_subflow_connect(struct sock *sk, const struct mptcp_addr_info *loc,
 
 	mptcp_pm_get_flags_and_ifindex_by_id(msk, local_id,
 					     &flags, &ifindex);
+	subflow->remote_key_valid = 1;
 	subflow->remote_key = msk->remote_key;
 	subflow->local_key = msk->local_key;
 	subflow->token = msk->token;
@@ -1873,6 +1885,7 @@ static void subflow_ulp_clone(const struct request_sock *req,
 		new_ctx->ssn_offset = subflow_req->ssn_offset;
 		new_ctx->mp_join = 1;
 		new_ctx->fully_established = 1;
+		new_ctx->remote_key_valid = 1;
 		new_ctx->backup = subflow_req->backup;
 		new_ctx->remote_id = subflow_req->remote_id;
 		new_ctx->token = subflow_req->token;