[IPSEC]: Added xfrm_decode_session_reverse and xfrmX_policy_check_reverse

RFC 4301 requires us to relookup ICMP traffic that does not match any
policies using the reverse of its payload.  This patch adds the functions
xfrm_decode_session_reverse and xfrmX_policy_check_reverse so we can get
the reverse flow to perform such a lookup.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 5 deletions

diff --git a/net/ipv4/xfrm4_policy.c b/net/ipv4/xfrm4_policy.c
index 10b72d185bb9..5ccae3a463c2 100644
--- a/net/ipv4/xfrm4_policy.c
+++ b/net/ipv4/xfrm4_policy.c
@@ -115,7 +115,7 @@ static int xfrm4_fill_dst(struct xfrm_dst *xdst, struct net_device *dev)
 }
 
 static void
-_decode_session4(struct sk_buff *skb, struct flowi *fl)
+_decode_session4(struct sk_buff *skb, struct flowi *fl, int reverse)
 {
         struct iphdr *iph = ip_hdr(skb);
         u8 *xprth = skb_network_header(skb) + iph->ihl * 4;
@@ -131,8 +131,8 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl)
                         if (pskb_may_pull(skb, xprth + 4 - skb->data)) {
                                 __be16 *ports = (__be16 *)xprth;
 
-                                fl->fl_ip_sport = ports[0];
-                                fl->fl_ip_dport = ports[1];
+                                fl->fl_ip_sport = ports[!!reverse];
+                                fl->fl_ip_dport = ports[!reverse];
                         }
                         break;
 
@@ -174,8 +174,8 @@ _decode_session4(struct sk_buff *skb, struct flowi *fl)
                 }
         }
         fl->proto = iph->protocol;
-        fl->fl4_dst = iph->daddr;
-        fl->fl4_src = iph->saddr;
+        fl->fl4_dst = reverse ? iph->saddr : iph->daddr;
+        fl->fl4_src = reverse ? iph->daddr : iph->saddr;
         fl->fl4_tos = iph->tos;
 }