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Commit 271c3b9b authored by Florian Westphal's avatar Florian Westphal Committed by David S. Miller
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tcp: honour SO_BINDTODEVICE for TW_RST case too 



Hannes points out that when we generate tcp reset for timewait sockets we
pretend we found no socket and pass NULL sk to tcp_vX_send_reset().

Make it cope with inet tw sockets and then provide tw sk.

This makes RSTs appear on correct interface when SO_BINDTODEVICE is used.

Packetdrill test case:
// want default route to be used, we rely on BINDTODEVICE
`ip route del 192.0.2.0/24 via 192.168.0.2 dev tun0`

0.000 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
// test case still works due to BINDTODEVICE
0.001 setsockopt(3, SOL_SOCKET, SO_BINDTODEVICE, "tun0", 4) = 0
0.100...0.200 connect(3, ..., ...) = 0

0.100 > S 0:0(0) <mss 1460,sackOK,nop,nop>
0.200 < S. 0:0(0) ack 1 win 32792 <mss 1460,sackOK,nop,nop>
0.200 > . 1:1(0) ack 1

0.210 close(3) = 0

0.210 > F. 1:1(0) ack 1 win 29200
0.300 < . 1:1(0) ack 2 win 46

// more data while in FIN_WAIT2, expect RST
1.300 < P. 1:1001(1000) ack 1 win 46

// fails without this change -- default route is used
1.301 > R 1:1(0) win 0

Reported-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarFlorian Westphal <fw@strlen.de>
Acked-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarHannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e46787f0

net/ipv4/tcp_ipv4.c

+9 −3
Original line number Diff line number Diff line
@@ -627,7 +627,7 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb) 
	net = sk ? sock_net(sk) : dev_net(skb_dst(skb)->dev);

#ifdef CONFIG_TCP_MD5SIG

	hash_location = tcp_parse_md5sig_option(th);

	if (sk) {

	if (sk && sk_fullsock(sk)) {

		key = tcp_md5_do_lookup(sk, (union tcp_md5_addr *)

					&ip_hdr(skb)->saddr, AF_INET);

	} else if (hash_location) {
@@ -674,7 +674,8 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb) 
				      ip_hdr(skb)->saddr, /* XXX */

				      arg.iov[0].iov_len, IPPROTO_TCP, 0);

	arg.csumoffset = offsetof(struct tcphdr, check) / 2;

	arg.flags = (sk && inet_sk(sk)->transparent) ? IP_REPLY_ARG_NOSRCCHECK : 0;

	arg.flags = (sk && inet_sk_transparent(sk)) ? IP_REPLY_ARG_NOSRCCHECK : 0;



	/* When socket is gone, all binding information is lost.

	 * routing might fail in this case. No choice here, if we choose to force

	 * input interface, we will misroute in case of asymmetric route.
@@ -682,6 +683,9 @@ static void tcp_v4_send_reset(const struct sock *sk, struct sk_buff *skb) 
	if (sk)

		arg.bound_dev_if = sk->sk_bound_dev_if;



	BUILD_BUG_ON(offsetof(struct sock, sk_bound_dev_if) !=

		     offsetof(struct inet_timewait_sock, tw_bound_dev_if));



	arg.tos = ip_hdr(skb)->tos;

	ip_send_unicast_reply(*this_cpu_ptr(net->ipv4.tcp_sk),

			      skb, &TCP_SKB_CB(skb)->header.h4.opt,
@@ -1705,7 +1709,9 @@ int tcp_v4_rcv(struct sk_buff *skb) 
		tcp_v4_timewait_ack(sk, skb);

		break;

	case TCP_TW_RST:

		goto no_tcp_socket;

		tcp_v4_send_reset(sk, skb);

		inet_twsk_deschedule_put(inet_twsk(sk));

		goto discard_it;

	case TCP_TW_SUCCESS:;

	}

	goto discard_it;

net/ipv4/tcp_minisocks.c

+2 −5
Original line number Diff line number Diff line
@@ -131,7 +131,7 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, 
			goto kill;



		if (th->syn && !before(TCP_SKB_CB(skb)->seq, tcptw->tw_rcv_nxt))

			goto kill_with_rst;

			return TCP_TW_RST;



		/* Dup ACK? */

		if (!th->ack ||
@@ -145,11 +145,8 @@ tcp_timewait_state_process(struct inet_timewait_sock *tw, struct sk_buff *skb, 
		 * reset.

		 */

		if (!th->fin ||

		    TCP_SKB_CB(skb)->end_seq != tcptw->tw_rcv_nxt + 1) {

kill_with_rst:

			inet_twsk_deschedule_put(tw);

		    TCP_SKB_CB(skb)->end_seq != tcptw->tw_rcv_nxt + 1)

			return TCP_TW_RST;

		}



		/* FIN arrived, enter true time-wait state. */

		tw->tw_substate	  = TCP_TIME_WAIT;

net/ipv6/tcp_ipv6.c

+4 −2
Original line number Diff line number Diff line
@@ -854,7 +854,7 @@ static void tcp_v6_send_reset(const struct sock *sk, struct sk_buff *skb) 


#ifdef CONFIG_TCP_MD5SIG

	hash_location = tcp_parse_md5sig_option(th);

	if (sk) {

	if (sk && sk_fullsock(sk)) {

		key = tcp_v6_md5_do_lookup(sk, &ipv6h->saddr);

	} else if (hash_location) {

		/*
@@ -1516,7 +1516,9 @@ static int tcp_v6_rcv(struct sk_buff *skb) 
		break;

	case TCP_TW_RST:

		tcp_v6_restore_cb(skb);

		goto no_tcp_socket;

		tcp_v6_send_reset(sk, skb);

		inet_twsk_deschedule_put(inet_twsk(sk));

		goto discard_it;

	case TCP_TW_SUCCESS:

		;

	}