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: 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>
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 1665f0f..a2780e5 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -336,8 +336,8 @@
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 @@
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 @@
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 @@
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 @@
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;