diff mbox series

[2/5] tcp: parse mptcp options contained in reset packets

Message ID 20201105170126.5627-3-fw@strlen.de
State Superseded, archived
Headers show
Series mptcp: add reset and fastclose option support | expand

Commit Message

Florian Westphal Nov. 5, 2020, 5:01 p.m. UTC 
In MPTCP, TCP-level resets only affect the subflow, not the logical
MPTCP connection.

MPTCP supports a reset-specific TCP option to enable senders to
tell the receiver why the subflow was reset, for instance due to a
protocol error, because the subflow is deemed too slow, a middlebox
interfering with mptcp options was detected and so on.

This allows an MPTCP receiver to make a decision to reopen the subflow
at a later time or even completely disable the path.

For this to work its needed to call the mptcp option decode function
when a tcp reset is received.

For this to be useful the reason code has to be propagated to the Path
Manager to use it to e.g. reconnect at a later time.

Signed-off-by: Florian Westphal <fw@strlen.de>
---
 include/net/tcp.h        |  2 +-
 net/ipv4/tcp_input.c     | 13 ++++++++-----
 net/ipv4/tcp_minisocks.c |  2 +-
 3 files changed, 10 insertions(+), 7 deletions(-)
diff mbox series

Patch

diff --git a/include/net/tcp.h b/include/net/tcp.h
index 8115164e0df6..c0fef9e9ba20 100644
--- a/include/net/tcp.h
+++ b/include/net/tcp.h
@@ -610,7 +610,7 @@  void tcp_skb_collapse_tstamp(struct sk_buff *skb,
 /* tcp_input.c */
 void tcp_rearm_rto(struct sock *sk);
 void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req);
-void tcp_reset(struct sock *sk);
+void tcp_reset(struct sock *sk, struct sk_buff *skb);
 void tcp_skb_mark_lost_uncond_verify(struct tcp_sock *tp, struct sk_buff *skb);
 void tcp_fin(struct sock *sk);
 
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c
index fb3a7750f623..fb65d3519439 100644
--- a/net/ipv4/tcp_input.c
+++ b/net/ipv4/tcp_input.c
@@ -4217,10 +4217,13 @@  static inline bool tcp_sequence(const struct tcp_sock *tp, u32 seq, u32 end_seq)
 }
 
 /* When we get a reset we do this. */
-void tcp_reset(struct sock *sk)
+void tcp_reset(struct sock *sk, struct sk_buff *skb)
 {
 	trace_tcp_receive_reset(sk);
 
+	if (sk_is_mptcp(sk))
+		mptcp_incoming_options(sk, skb);
+
 	/* We want the right error as BSD sees it (and indeed as we do). */
 	switch (sk->sk_state) {
 	case TCP_SYN_SENT:
@@ -5603,7 +5606,7 @@  static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
 						  &tp->last_oow_ack_time))
 				tcp_send_dupack(sk, skb);
 		} else if (tcp_reset_check(sk, skb)) {
-			tcp_reset(sk);
+			tcp_reset(sk, skb);
 		}
 		goto discard;
 	}
@@ -5639,7 +5642,7 @@  static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb,
 		}
 
 		if (rst_seq_match)
-			tcp_reset(sk);
+			tcp_reset(sk, skb);
 		else {
 			/* Disable TFO if RST is out-of-order
 			 * and no data has been received
@@ -6076,7 +6079,7 @@  static int tcp_rcv_synsent_state_process(struct sock *sk, struct sk_buff *skb,
 		 */
 
 		if (th->rst) {
-			tcp_reset(sk);
+			tcp_reset(sk, skb);
 			goto discard;
 		}
 
@@ -6518,7 +6521,7 @@  int tcp_rcv_state_process(struct sock *sk, struct sk_buff *skb)
 			if (TCP_SKB_CB(skb)->end_seq != TCP_SKB_CB(skb)->seq &&
 			    after(TCP_SKB_CB(skb)->end_seq - th->fin, tp->rcv_nxt)) {
 				NET_INC_STATS(sock_net(sk), LINUX_MIB_TCPABORTONDATA);
-				tcp_reset(sk);
+				tcp_reset(sk, skb);
 				return 1;
 			}
 		}
diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
index 495dda2449fe..0055ae0a3bf8 100644
--- a/net/ipv4/tcp_minisocks.c
+++ b/net/ipv4/tcp_minisocks.c
@@ -801,7 +801,7 @@  struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb,
 		req->rsk_ops->send_reset(sk, skb);
 	} else if (fastopen) { /* received a valid RST pkt */
 		reqsk_fastopen_remove(sk, req, true);
-		tcp_reset(sk);
+		tcp_reset(sk, skb);
 	}
 	if (!fastopen) {
 		inet_csk_reqsk_queue_drop(sk, req);