tcp: reflect SYN queue_mapping into SYNACK packets
While testing how linux behaves on SYNFLOOD attack on multiqueue device
(ixgbe), I found that SYNACK messages were dropped at Qdisc level
because we send them all on a single queue.
Obvious choice is to reflect incoming SYN packet @queue_mapping to
SYNACK packet.
Under stress, my machine could only send 25.000 SYNACK per second (for
200.000 incoming SYN per second). NIC : ixgbe with 16 rx/tx queues.
After patch, not a single SYNACK is dropped.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Hans Schillstrom <hans.schillstrom@ericsson.com>
Cc: Jesper Dangaard Brouer <brouer@redhat.com>
Cc: Neal Cardwell <ncardwell@google.com>
Cc: Tom Herbert <therbert@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 554d599..3a9aec2 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -476,7 +476,8 @@
static int tcp_v6_send_synack(struct sock *sk, struct request_sock *req,
- struct request_values *rvp)
+ struct request_values *rvp,
+ u16 queue_mapping)
{
struct inet6_request_sock *treq = inet6_rsk(req);
struct ipv6_pinfo *np = inet6_sk(sk);
@@ -513,6 +514,7 @@
__tcp_v6_send_check(skb, &treq->loc_addr, &treq->rmt_addr);
fl6.daddr = treq->rmt_addr;
+ skb_set_queue_mapping(skb, queue_mapping);
err = ip6_xmit(sk, skb, &fl6, opt, np->tclass);
err = net_xmit_eval(err);
}
@@ -528,7 +530,7 @@
struct request_values *rvp)
{
TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS);
- return tcp_v6_send_synack(sk, req, rvp);
+ return tcp_v6_send_synack(sk, req, rvp, 0);
}
static void tcp_v6_reqsk_destructor(struct request_sock *req)
@@ -1213,7 +1215,8 @@
security_inet_conn_request(sk, skb, req);
if (tcp_v6_send_synack(sk, req,
- (struct request_values *)&tmp_ext) ||
+ (struct request_values *)&tmp_ext,
+ skb_get_queue_mapping(skb)) ||
want_cookie)
goto drop_and_free;