[PATCH AUTOSEL for 4.15 007/124] ipv6: Reinject IPv6 packets if IPsec policy matches after SNAT

[Sasha Levin]

From: Tobias Brunner <tobias@xxxxxxxxxxxxxx>

[ Upstream commit 09ee9dba9611cd382fd360a99ad1c2fa23bfdca8 ]

If SNAT modifies the source address the resulting packet might match
an IPsec policy, reinject the packet if that's the case.

The exact same thing is already done for IPv4.

Signed-off-by: Tobias Brunner <tobias@xxxxxxxxxxxxxx>
Acked-by: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
---
 net/ipv6/ip6_output.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/ipv6/ip6_output.c b/net/ipv6/ip6_output.c
index 3763dc01e374..0f874b48c1b5 100644
--- a/net/ipv6/ip6_output.c
+++ b/net/ipv6/ip6_output.c
@@ -138,6 +138,14 @@ static int ip6_finish_output(struct net *net, struct sock *sk, struct sk_buff *s
 		return ret;
 	}
 
+#if defined(CONFIG_NETFILTER) && defined(CONFIG_XFRM)
+	/* Policy lookup after SNAT yielded a new policy */
+	if (skb_dst(skb)->xfrm) {
+		IPCB(skb)->flags |= IPSKB_REROUTED;
+		return dst_output(net, sk, skb);
+	}
+#endif
+
 	if ((skb->len > ip6_skb_dst_mtu(skb) && !skb_is_gso(skb)) ||
 	    dst_allfrag(skb_dst(skb)) ||
 	    (IP6CB(skb)->frag_max_size && skb->len > IP6CB(skb)->frag_max_size))
-- 
2.14.1