tcp: fix syncookie regression
commit ea4fc0d619 (ipv4: Don't use rt->rt_{src,dst} in ip_queue_xmit())
added a serious regression on synflood handling.
Simon Kirby discovered a successful connection was delayed by 20 seconds
before being responsive.
In my tests, I discovered that xmit frames were lost, and needed ~4
retransmits and a socket dst rebuild before being really sent.
In case of syncookie initiated connection, we use a different path to
initialize the socket dst, and inet->cork.fl.u.ip4 is left cleared.
As ip_queue_xmit() now depends on inet flow being setup, fix this by
copying the temp flowi4 we use in cookie_v4_check().
Reported-by: Simon Kirby <sim@netnation.com>
Bisected-by: Simon Kirby <sim@netnation.com>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Tested-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c
index 51fdbb4..eab2a7f 100644
--- a/net/ipv4/syncookies.c
+++ b/net/ipv4/syncookies.c
@@ -278,6 +278,7 @@
struct rtable *rt;
__u8 rcv_wscale;
bool ecn_ok = false;
+ struct flowi4 fl4;
if (!sysctl_tcp_syncookies || !th->ack || th->rst)
goto out;
@@ -346,20 +347,16 @@
* hasn't changed since we received the original syn, but I see
* no easy way to do this.
*/
- {
- struct flowi4 fl4;
-
- flowi4_init_output(&fl4, 0, sk->sk_mark, RT_CONN_FLAGS(sk),
- RT_SCOPE_UNIVERSE, IPPROTO_TCP,
- inet_sk_flowi_flags(sk),
- (opt && opt->srr) ? opt->faddr : ireq->rmt_addr,
- ireq->loc_addr, th->source, th->dest);
- security_req_classify_flow(req, flowi4_to_flowi(&fl4));
- rt = ip_route_output_key(sock_net(sk), &fl4);
- if (IS_ERR(rt)) {
- reqsk_free(req);
- goto out;
- }
+ flowi4_init_output(&fl4, 0, sk->sk_mark, RT_CONN_FLAGS(sk),
+ RT_SCOPE_UNIVERSE, IPPROTO_TCP,
+ inet_sk_flowi_flags(sk),
+ (opt && opt->srr) ? opt->faddr : ireq->rmt_addr,
+ ireq->loc_addr, th->source, th->dest);
+ security_req_classify_flow(req, flowi4_to_flowi(&fl4));
+ rt = ip_route_output_key(sock_net(sk), &fl4);
+ if (IS_ERR(rt)) {
+ reqsk_free(req);
+ goto out;
}
/* Try to redo what tcp_v4_send_synack did. */
@@ -373,5 +370,10 @@
ireq->rcv_wscale = rcv_wscale;
ret = get_cookie_sock(sk, skb, req, &rt->dst);
+ /* ip_queue_xmit() depends on our flow being setup
+ * Normal sockets get it right from inet_csk_route_child_sock()
+ */
+ if (ret)
+ inet_sk(ret)->cork.fl.u.ip4 = fl4;
out: return ret;
}