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tcp: improve fastopen icmp handling
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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: Yuchung Cheng <ycheng@google.com>
Signed-off-by: Daniel Lee <longinus00@gmail.com>
Signed-off-by: Jerry Chu <hkchu@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Yuchung Cheng authored and David S. Miller committed May 13, 2014
1 parent 843f4a5 commit 0a672f7
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Showing 2 changed files with 31 additions and 26 deletions.
35 changes: 14 additions & 21 deletions net/ipv4/tcp_ipv4.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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);
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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:
Expand Down Expand Up @@ -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;

Expand Down
22 changes: 17 additions & 5 deletions net/ipv6/tcp_ipv6.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -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,
Expand Down Expand Up @@ -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;
}
Expand Down Expand Up @@ -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) */
Expand Down Expand Up @@ -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;
Expand Down Expand Up @@ -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)
);
}

Expand Down

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