[net, 2/2] seg6: fix skb transport_header after decap_and_validate()

From: Andrea Mayer
Date: Sat Nov 16 2019 - 10:13:59 EST

in the receive path (more precisely in ip6_rcv_core()) the
skb->transport_header is set to skb->network_header + sizeof(*hdr). As a
consequence, after routing operations, destination input expects to find
skb->transport_header correctly set to the next protocol (or extension
header) that follows the network protocol. However, decap behaviors (DX*,
DT*) remove the outer IPv6 and SRH extension and do not set again the
skb->transport_header pointer correctly. For this reason, the patch sets
the skb->transport_header to the skb->network_header + sizeof(hdr) in each
DX* and DT* behavior.

Signed-off-by: Andrea Mayer <andrea.mayer@xxxxxxxxxxx>
net/ipv6/seg6_local.c | 6 ++++++
1 file changed, 6 insertions(+)

diff --git a/net/ipv6/seg6_local.c b/net/ipv6/seg6_local.c
index 5e3d7004d431..e70567446f28 100644
--- a/net/ipv6/seg6_local.c
+++ b/net/ipv6/seg6_local.c
@@ -341,6 +341,8 @@ static int input_action_end_dx6(struct sk_buff *skb,
if (!ipv6_addr_any(&slwt->nh6))
nhaddr = &slwt->nh6;

+ skb_set_transport_header(skb, sizeof(struct ipv6hdr));
seg6_lookup_nexthop(skb, nhaddr, 0);

return dst_input(skb);
@@ -370,6 +372,8 @@ static int input_action_end_dx4(struct sk_buff *skb,


+ skb_set_transport_header(skb, sizeof(struct iphdr));
err = ip_route_input(skb, nhaddr, iph->saddr, 0, skb->dev);
if (err)
goto drop;
@@ -390,6 +394,8 @@ static int input_action_end_dt6(struct sk_buff *skb,
if (!pskb_may_pull(skb, sizeof(struct ipv6hdr)))
goto drop;

+ skb_set_transport_header(skb, sizeof(struct ipv6hdr));
seg6_lookup_nexthop(skb, NULL, slwt->table);

return dst_input(skb);