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From:   Sasha Levin <Alexander.Levin@microsoft.com>
To:     "stable@vger.kernel.org" <stable@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
CC:     Chenbo Feng <fengc@google.com>,
        "David S . Miller" <davem@davemloft.net>,
        Sasha Levin <Alexander.Levin@microsoft.com>
Subject: [PATCH AUTOSEL for 4.9 122/293] tcp: Add a tcp_filter hook before
 handle ack packet
Thread-Topic: [PATCH AUTOSEL for 4.9 122/293] tcp: Add a tcp_filter hook
 before handle ack packet
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Date:   Mon, 9 Apr 2018 00:24:28 +0000
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From: Chenbo Feng <fengc@google.com>

[ Upstream commit 8fac365f63c866a00015fa13932d8ffc584518b8 ]

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>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
---
 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 b3960738464e..7294a1106b75 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1677,6 +1677,8 @@ process:
 		}
 		if (nsk =3D=3D 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 eb624547382f..149b9b3cbd66 100644
--- a/net/ipv6/tcp_ipv6.c
+++ b/net/ipv6/tcp_ipv6.c
@@ -1447,6 +1447,8 @@ process:
 		if (nsk =3D=3D 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;
--=20
2.15.1