gre6: Fix reception with IP6_TNL_F_RCV_DSCP_COPY

[ Upstream commit 272502fcb7cda01ab07fc2fcff82d1d2f73d43cc ]

When receiving an IPv4 packet inside an IPv6 GRE packet, and the
IP6_TNL_F_RCV_DSCP_COPY flag is set on the tunnel, the IPv4 header would
get corrupted. This is due to the common ip6_tnl_rcv() function assuming
that the inner header is always IPv6. This patch checks the tunnel
protocol for IPv4 inner packets, but still defaults to IPv6.

Fixes: 308edfdf1563 ("gre6: Cleanup GREv6 receive path, call common GRE functions")
Signed-off-by: Mark Tomlinson <mark.tomlinson@alliedtelesis.co.nz>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/net/ipv6/ip6_tunnel.c b/net/ipv6/ip6_tunnel.c
index ed795d50a8d2b39d526673f51fc3d5c11af345a6..d9e60aa2ea1b232118e9c869f620a610b460ce06 100644 (file)
--- a/net/ipv6/ip6_tunnel.c
+++ b/net/ipv6/ip6_tunnel.c
@@ -871,7 +871,15 @@ int ip6_tnl_rcv(struct ip6_tnl *t, struct sk_buff *skb,
                struct metadata_dst *tun_dst,
                bool log_ecn_err)
 {
-       return __ip6_tnl_rcv(t, skb, tpi, NULL, ip6ip6_dscp_ecn_decapsulate,
+       int (*dscp_ecn_decapsulate)(const struct ip6_tnl *t,
+                                   const struct ipv6hdr *ipv6h,
+                                   struct sk_buff *skb);
+
+       dscp_ecn_decapsulate = ip6ip6_dscp_ecn_decapsulate;
+       if (tpi->proto == htons(ETH_P_IP))
+               dscp_ecn_decapsulate = ip4ip6_dscp_ecn_decapsulate;
+
+       return __ip6_tnl_rcv(t, skb, tpi, NULL, dscp_ecn_decapsulate,
                             log_ecn_err);
 }
 EXPORT_SYMBOL(ip6_tnl_rcv);