From: Chenbo Feng <fengc@google.com>
Date: Tue, 20 Jun 2017 19:06:40 -0700
Subject: tcp: Add a tcp_filter hook before handle ack packet
Patch-mainline: v4.13-rc1
Git-commit: 8fac365f63c866a00015fa13932d8ffc584518b8
References: bsc#1076830

Currently in both ipv4 and ipv6 code path, the ack packet received when
sk at TCP_NEW_SYN_RECV state is not filtered by socket filter or cgroup
filter since it is handled from tcp_child_process and never reaches the
tcp_filter inside tcp_v4_rcv or tcp_v6_rcv. Adding a tcp_filter hooks
here can make sure all the ingress tcp packet can be correctly filtered.

Signed-off-by: Chenbo Feng <fengc@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Michal Kubecek <mkubecek@suse.cz>

---
 net/ipv4/tcp_ipv4.c | 2 ++
 net/ipv6/tcp_ipv6.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index dbedc3f39b56..e480b77c7f6c 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1623,6 +1623,8 @@ int tcp_v4_rcv(struct sk_buff *skb)
 		}
 		if (nsk == sk) {
 			reqsk_put(req);
+		} else if (tcp_filter(sk, skb)) {
+			goto discard_and_relse;
 		} else if (tcp_child_process(sk, nsk, skb)) {
 			tcp_v4_send_reset(nsk, skb);
 			goto discard_and_relse;
diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c
index 05b5130fe475..13dee4a93812 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1453,6 +1453,8 @@ static int tcp_v6_rcv(struct sk_buff *skb)
 		if (nsk == sk) {
 			reqsk_put(req);
 			tcp_v6_restore_cb(skb);
+		} else if (tcp_filter(sk, skb)) {
+			goto discard_and_relse;
 		} else if (tcp_child_process(sk, nsk, skb)) {
 			tcp_v6_send_reset(nsk, skb);
 			goto discard_and_relse;
-- 
2.16.2