diff options
author | Gao Feng <fgao@ikuai8.com> | 2017-04-20 14:01:45 +0800 |
---|---|---|
committer | Pablo Neira Ayuso <pablo@netfilter.org> | 2017-04-26 09:30:22 +0200 |
commit | 495dcb56d09ddb63afe30e799af41876c3f061cc (patch) | |
tree | a1f3b7af426436ea25763e5c8f5fe58d29c63263 /net | |
parent | aee12a0a3727e16fb837367c4755cb6daaf45109 (diff) |
netfilter: SYNPROXY: Return NF_STOLEN instead of NF_DROP during handshaking
Current SYNPROXY codes return NF_DROP during normal TCP handshaking,
it is not friendly to caller. Because the nf_hook_slow would treat
the NF_DROP as an error, and return -EPERM.
As a result, it may cause the top caller think it meets one error.
For example, the following codes are from cfv_rx_poll()
err = netif_receive_skb(skb);
if (unlikely(err)) {
++cfv->ndev->stats.rx_dropped;
} else {
++cfv->ndev->stats.rx_packets;
cfv->ndev->stats.rx_bytes += skb_len;
}
When SYNPROXY returns NF_DROP, then netif_receive_skb returns -EPERM.
As a result, the cfv driver would treat it as an error, and increase
the rx_dropped counter.
So use NF_STOLEN instead of NF_DROP now because there is no error
happened indeed, and free the skb directly.
Signed-off-by: Gao Feng <fgao@ikuai8.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r-- | net/ipv4/netfilter/ipt_SYNPROXY.c | 21 | ||||
-rw-r--r-- | net/ipv6/netfilter/ip6t_SYNPROXY.c | 20 |
2 files changed, 28 insertions, 13 deletions
diff --git a/net/ipv4/netfilter/ipt_SYNPROXY.c b/net/ipv4/netfilter/ipt_SYNPROXY.c index c308ee0ee0bc..af2b69b6895f 100644 --- a/net/ipv4/netfilter/ipt_SYNPROXY.c +++ b/net/ipv4/netfilter/ipt_SYNPROXY.c @@ -293,12 +293,16 @@ synproxy_tg4(struct sk_buff *skb, const struct xt_action_param *par) XT_SYNPROXY_OPT_ECN); synproxy_send_client_synack(net, skb, th, &opts); - return NF_DROP; - + consume_skb(skb); + return NF_STOLEN; } else if (th->ack && !(th->fin || th->rst || th->syn)) { /* ACK from client */ - synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq)); - return NF_DROP; + if (synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq))) { + consume_skb(skb); + return NF_STOLEN; + } else { + return NF_DROP; + } } return XT_CONTINUE; @@ -367,10 +371,13 @@ static unsigned int ipv4_synproxy_hook(void *priv, * number match the one of first SYN. */ if (synproxy_recv_client_ack(net, skb, th, &opts, - ntohl(th->seq) + 1)) + ntohl(th->seq) + 1)) { this_cpu_inc(snet->stats->cookie_retrans); - - return NF_DROP; + consume_skb(skb); + return NF_STOLEN; + } else { + return NF_DROP; + } } synproxy->isn = ntohl(th->ack_seq); diff --git a/net/ipv6/netfilter/ip6t_SYNPROXY.c b/net/ipv6/netfilter/ip6t_SYNPROXY.c index 1252537f215f..d3c4daa708b9 100644 --- a/net/ipv6/netfilter/ip6t_SYNPROXY.c +++ b/net/ipv6/netfilter/ip6t_SYNPROXY.c @@ -307,12 +307,17 @@ synproxy_tg6(struct sk_buff *skb, const struct xt_action_param *par) XT_SYNPROXY_OPT_ECN); synproxy_send_client_synack(net, skb, th, &opts); - return NF_DROP; + consume_skb(skb); + return NF_STOLEN; } else if (th->ack && !(th->fin || th->rst || th->syn)) { /* ACK from client */ - synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq)); - return NF_DROP; + if (synproxy_recv_client_ack(net, skb, th, &opts, ntohl(th->seq))) { + consume_skb(skb); + return NF_STOLEN; + } else { + return NF_DROP; + } } return XT_CONTINUE; @@ -388,10 +393,13 @@ static unsigned int ipv6_synproxy_hook(void *priv, * number match the one of first SYN. */ if (synproxy_recv_client_ack(net, skb, th, &opts, - ntohl(th->seq) + 1)) + ntohl(th->seq) + 1)) { this_cpu_inc(snet->stats->cookie_retrans); - - return NF_DROP; + consume_skb(skb); + return NF_STOLEN; + } else { + return NF_DROP; + } } synproxy->isn = ntohl(th->ack_seq); |