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authorGuillaume Nault <gnault@redhat.com>2021-06-25 15:33:08 +0200
committerDavid S. Miller <davem@davemloft.net>2021-06-28 12:44:17 -0700
commit730eed2772e740c30229d03e3d578cc00a5ae304 (patch)
tree9a2cb74aaa158dab88e2dfb5d31f684bdee20cf4 /net/ipv6
parent7ad136fd288c0e0177eb29e04ec289e1b873b270 (diff)
sit: allow redirecting ip6ip, ipip and mplsip packets to eth devices
Even though sit transports L3 data (IPv6, IPv4 or MPLS) packets, it needs to reset the mac_header pointer, so that other parts of the stack don't mistakenly access the outer header after the packet has been decapsulated. There are two rx handlers to modify: ipip6_rcv() for the ip6ip mode and sit_tunnel_rcv() which is used to re-implement the ipip and mplsip modes of ipip.ko. This allows to push an Ethernet header to sit packets and redirect them to an Ethernet device: $ tc filter add dev sit0 ingress matchall \ action vlan push_eth dst_mac 00:00:5e:00:53:01 \ src_mac 00:00:5e:00:53:00 \ action mirred egress redirect dev eth0 Without this patch, push_eth refuses to add an ethernet header because the skb appears to already have a MAC header. Signed-off-by: Guillaume Nault <gnault@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
-rw-r--r--net/ipv6/sit.c4
1 files changed, 4 insertions, 0 deletions
diff --git a/net/ipv6/sit.c b/net/ipv6/sit.c
index e0a39b0bb4c1..df5bea818410 100644
--- a/net/ipv6/sit.c
+++ b/net/ipv6/sit.c
@@ -710,6 +710,8 @@ static int ipip6_rcv(struct sk_buff *skb)
* old iph is no longer valid
*/
iph = (const struct iphdr *)skb_mac_header(skb);
+ skb_reset_mac_header(skb);
+
err = IP_ECN_decapsulate(iph, skb);
if (unlikely(err)) {
if (log_ecn_error)
@@ -780,6 +782,8 @@ static int sit_tunnel_rcv(struct sk_buff *skb, u8 ipproto)
tpi = &ipip_tpi;
if (iptunnel_pull_header(skb, 0, tpi->proto, false))
goto drop;
+ skb_reset_mac_header(skb);
+
return ip_tunnel_rcv(tunnel, skb, tpi, NULL, log_ecn_error);
}