[PATCH] xfrm: fix inbound ipv4/udp/esp packets to UDPv6 dualstack sockets

["Maciej Żenczykowski" <zenczykowski@gmail.com>]

From: Maciej Żenczykowski <maze@google.com>

Before Linux v5.8 an AF_INET6 SOCK_DGRAM (udp/udplite) socket
with SOL_UDP, UDP_ENCAP, UDP_ENCAP_ESPINUDP{,_NON_IKE} enabled
would just unconditionally use xfrm4_udp_encap_rcv(), afterwards
such a socket would use the newly added xfrm6_udp_encap_rcv()
which only handles IPv6 packets.

Cc: Sabrina Dubroca <sd@queasysnail.net>
Cc: Steffen Klassert <steffen.klassert@secunet.com>
Fixes: 0146dca70b87 ('xfrm: add support for UDPv6 encapsulation of ESP')
Signed-off-by: Maciej Żenczykowski <maze@google.com>
---
 net/ipv6/xfrm6_input.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/net/ipv6/xfrm6_input.c b/net/ipv6/xfrm6_input.c
index 04cbeefd8982..2d1c75b42709 100644
--- a/net/ipv6/xfrm6_input.c
+++ b/net/ipv6/xfrm6_input.c
@@ -86,6 +86,9 @@ int xfrm6_udp_encap_rcv(struct sock *sk, struct sk_buff *skb)
 	__be32 *udpdata32;
 	__u16 encap_type = up->encap_type;
 
+	if (skb->protocol == htons(ETH_P_IP))
+		xfrm4_udp_encap_rcv(sk, skb);
+
 	/* if this is not encapsulated socket, then just return now */
 	if (!encap_type)
 		return 1;
-- 
2.38.0.135.g90850a2211-goog