[PATCH v2] tcp: reflect SYN queue_mapping into SYNACK packets
From: Eric Dumazet <hidden>
Date: 2012-06-01 11:47:57
From: Eric Dumazet <edumazet@google.com> 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 <redacted> Cc: Jesper Dangaard Brouer <redacted> Cc: Neal Cardwell <ncardwell@google.com> Cc: Tom Herbert <redacted> --- v2: add IPv6 part net/ipv4/tcp_ipv4.c | 9 ++++++--- net/ipv6/tcp_ipv6.c | 9 ++++++--- 2 files changed, 12 insertions(+), 6 deletions(-)
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index a43b87d..c8d28c4 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c@@ -824,7 +824,8 @@ static void tcp_v4_reqsk_send_ack(struct sock *sk, struct sk_buff *skb, */ static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst, struct request_sock *req, - struct request_values *rvp) + struct request_values *rvp, + u16 queue_mapping) { const struct inet_request_sock *ireq = inet_rsk(req); struct flowi4 fl4;
@@ -840,6 +841,7 @@ static int tcp_v4_send_synack(struct sock *sk, struct dst_entry *dst, if (skb) { __tcp_v4_send_check(skb, ireq->loc_addr, ireq->rmt_addr); + skb_set_queue_mapping(skb, queue_mapping); err = ip_build_and_send_pkt(skb, sk, ireq->loc_addr, ireq->rmt_addr, ireq->opt);
@@ -854,7 +856,7 @@ static int tcp_v4_rtx_synack(struct sock *sk, struct request_sock *req, struct request_values *rvp) { TCP_INC_STATS_BH(sock_net(sk), TCP_MIB_RETRANSSEGS); - return tcp_v4_send_synack(sk, NULL, req, rvp); + return tcp_v4_send_synack(sk, NULL, req, rvp, 0); } /*
@@ -1422,7 +1424,8 @@ int tcp_v4_conn_request(struct sock *sk, struct sk_buff *skb) tcp_rsk(req)->snt_synack = tcp_time_stamp; if (tcp_v4_send_synack(sk, dst, req, - (struct request_values *)&tmp_ext) || + (struct request_values *)&tmp_ext, + skb_get_queue_mapping(skb)) || want_cookie) goto drop_and_free;
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 @@ out: 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 @@ static int tcp_v6_send_synack(struct sock *sk, struct request_sock *req, __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 @@ static int tcp_v6_rtx_synack(struct sock *sk, struct request_sock *req, 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 @@ have_isn: 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;