[NETFILTER]: Fix xfrm lookup in ip_route_me_harder/ip6_route_me_harder

ip_route_me_harder doesn't use the port numbers of the xfrm lookup and
uses ip_route_input for non-local addresses which doesn't do a xfrm
lookup, ip6_route_me_harder doesn't do a xfrm lookup at all.

Use xfrm_decode_session and do the lookup manually, make sure both
only do the lookup if the packet hasn't been transformed already.

Makeing sure the lookup only happens once needs a new field in the
IP6CB, which exceeds the size of skb->cb. The size of skb->cb is
increased to 48b. Apparently the IPv6 mobile extensions need some
more room anyway.

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 9 insertions, 1 deletions

diff --git a/net/ipv6/netfilter.c b/net/ipv6/netfilter.c
index f8626ebf90fd..b63678328a3b 100644
--- a/net/ipv6/netfilter.c
+++ b/net/ipv6/netfilter.c
@@ -10,6 +10,7 @@
 #include <net/dst.h>
 #include <net/ipv6.h>
 #include <net/ip6_route.h>
+#include <net/xfrm.h>
 
 int ip6_route_me_harder(struct sk_buff *skb)
 {
@@ -21,11 +22,17 @@ int ip6_route_me_harder(struct sk_buff *skb)
                 { .ip6_u =
                   { .daddr = iph->daddr,
                     .saddr = iph->saddr, } },
-                .proto = iph->nexthdr,
         };
 
         dst = ip6_route_output(skb->sk, &fl);
 
+#ifdef CONFIG_XFRM
+        if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
+            xfrm_decode_session(skb, &fl, AF_INET6) == 0)
+                if (xfrm_lookup(&skb->dst, &fl, skb->sk, 0))
+                        return -1;
+#endif
+
         if (dst->error) {
                 IP6_INC_STATS(IPSTATS_MIB_OUTNOROUTES);
                 LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
diff --git a/net/ipv6/xfrm6_output.c b/net/ipv6/xfrm6_output.c
index fc0ea38953c4..80242172a5df 100644
--- a/net/ipv6/xfrm6_output.c
+++ b/net/ipv6/xfrm6_output.c
@@ -139,6 +139,7 @@ static int xfrm6_output_one(struct sk_buff *skb)
                 x = dst->xfrm;
         } while (x && !x->props.mode);
 
+        IP6CB(skb)->flags |= IP6SKB_XFRM_TRANSFORMED;
         err = 0;
 
 out_exit: