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Commit 0a672f74 authored by Yuchung Cheng's avatar Yuchung Cheng Committed by David S. Miller
Browse files

tcp: improve fastopen icmp handling 



If a fast open socket is already accepted by the user, it should
be treated like a connected socket to record the ICMP error in
sk_softerr, so the user can fetch it. Do that in both tcp_v4_err
and tcp_v6_err.

Also refactor the sequence window check to improve readability
(e.g., there were two local variables named 'req').

Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarDaniel Lee <longinus00@gmail.com>
Signed-off-by: default avatarJerry Chu <hkchu@google.com>
Acked-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 843f4a55

net/ipv4/tcp_ipv4.c

+14 −21
Original line number Diff line number Diff line
@@ -336,8 +336,8 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info) 
	const int code = icmp_hdr(icmp_skb)->code;

	struct sock *sk;

	struct sk_buff *skb;

	struct request_sock *req;

	__u32 seq;

	struct request_sock *fastopen;

	__u32 seq, snd_una;

	__u32 remaining;

	int err;

	struct net *net = dev_net(icmp_skb->dev);
@@ -378,12 +378,12 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info) 


	icsk = inet_csk(sk);

	tp = tcp_sk(sk);

	req = tp->fastopen_rsk;

	seq = ntohl(th->seq);

	/* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */

	fastopen = tp->fastopen_rsk;

	snd_una = fastopen ? tcp_rsk(fastopen)->snt_isn : tp->snd_una;

	if (sk->sk_state != TCP_LISTEN &&

	    !between(seq, tp->snd_una, tp->snd_nxt) &&

	    (req == NULL || seq != tcp_rsk(req)->snt_isn)) {

		/* For a Fast Open socket, allow seq to be snt_isn. */

	    !between(seq, snd_una, tp->snd_nxt)) {

		NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);

		goto out;

	}
@@ -426,11 +426,9 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info) 
		if (code != ICMP_NET_UNREACH && code != ICMP_HOST_UNREACH)

			break;

		if (seq != tp->snd_una  || !icsk->icsk_retransmits ||

		    !icsk->icsk_backoff)

		    !icsk->icsk_backoff || fastopen)

			break;



		/* XXX (TFO) - revisit the following logic for TFO */



		if (sock_owned_by_user(sk))

			break;
@@ -462,14 +460,6 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info) 
		goto out;

	}



	/* XXX (TFO) - if it's a TFO socket and has been accepted, rather

	 * than following the TCP_SYN_RECV case and closing the socket,

	 * we ignore the ICMP error and keep trying like a fully established

	 * socket. Is this the right thing to do?

	 */

	if (req && req->sk == NULL)

		goto out;



	switch (sk->sk_state) {

		struct request_sock *req, **prev;

	case TCP_LISTEN:
@@ -502,10 +492,13 @@ void tcp_v4_err(struct sk_buff *icmp_skb, u32 info) 
		goto out;



	case TCP_SYN_SENT:

	case TCP_SYN_RECV:  /* Cannot happen.

			       It can f.e. if SYNs crossed,

			       or Fast Open.

	case TCP_SYN_RECV:

		/* Only in fast or simultaneous open. If a fast open socket is

		 * is already accepted it is treated as a connected one below.

		 */

		if (fastopen && fastopen->sk == NULL)

			break;



		if (!sock_owned_by_user(sk)) {

			sk->sk_err = err;

net/ipv6/tcp_ipv6.c

+17 −5
Original line number Diff line number Diff line
@@ -340,7 +340,8 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 
	struct sock *sk;

	int err;

	struct tcp_sock *tp;

	__u32 seq;

	struct request_sock *fastopen;

	__u32 seq, snd_una;

	struct net *net = dev_net(skb->dev);



	sk = inet6_lookup(net, &tcp_hashinfo, &hdr->daddr,
@@ -371,8 +372,11 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 


	tp = tcp_sk(sk);

	seq = ntohl(th->seq);

	/* XXX (TFO) - tp->snd_una should be ISN (tcp_create_openreq_child() */

	fastopen = tp->fastopen_rsk;

	snd_una = fastopen ? tcp_rsk(fastopen)->snt_isn : tp->snd_una;

	if (sk->sk_state != TCP_LISTEN &&

	    !between(seq, tp->snd_una, tp->snd_nxt)) {

	    !between(seq, snd_una, tp->snd_nxt)) {

		NET_INC_STATS_BH(net, LINUX_MIB_OUTOFWINDOWICMPS);

		goto out;

	}
@@ -436,8 +440,13 @@ static void tcp_v6_err(struct sk_buff *skb, struct inet6_skb_parm *opt, 
		goto out;



	case TCP_SYN_SENT:

	case TCP_SYN_RECV:  /* Cannot happen.

			       It can, it SYNs are crossed. --ANK */

	case TCP_SYN_RECV:

		/* Only in fast or simultaneous open. If a fast open socket is

		 * is already accepted it is treated as a connected one below.

		 */

		if (fastopen && fastopen->sk == NULL)

			break;



		if (!sock_owned_by_user(sk)) {

			sk->sk_err = err;

			sk->sk_error_report(sk);		/* Wake people up to see the error (see connect in sock.c) */
@@ -1760,6 +1769,7 @@ static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i) 
	const struct inet_sock *inet = inet_sk(sp);

	const struct tcp_sock *tp = tcp_sk(sp);

	const struct inet_connection_sock *icsk = inet_csk(sp);

	struct fastopen_queue *fastopenq = icsk->icsk_accept_queue.fastopenq;



	dest  = &sp->sk_v6_daddr;

	src   = &sp->sk_v6_rcv_saddr;
@@ -1802,7 +1812,9 @@ static void get_tcp6_sock(struct seq_file *seq, struct sock *sp, int i) 
		   jiffies_to_clock_t(icsk->icsk_ack.ato),

		   (icsk->icsk_ack.quick << 1) | icsk->icsk_ack.pingpong,

		   tp->snd_cwnd,

		   tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh

		   sp->sk_state == TCP_LISTEN ?

			(fastopenq ? fastopenq->max_qlen : 0) :

			(tcp_in_initial_slowstart(tp) ? -1 : tp->snd_ssthresh)

		   );

}