[IPSEC]: Add ICMP host relookup support

RFC 4301 requires us to relookup ICMP traffic that does not match any
policies using the reverse of its payload.  This patch implements this
for ICMP traffic that originates from or terminates on localhost.

This is activated on outbound with the new policy flag XFRM_POLICY_ICMP,
and on inbound by the new state flag XFRM_STATE_ICMP.

On inbound the policy check is now performed by the ICMP protocol so
that it can repeat the policy check where necessary.

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

1 files changed, 1 insertions, 0 deletions

diff --git a/include/net/dst.h b/include/net/dst.h
index aaa2dbb50179..31468c9aa877 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -268,6 +268,7 @@ extern void		dst_init(void);
 /* Flags for xfrm_lookup flags argument. */
 enum {
         XFRM_LOOKUP_WAIT = 1 << 0,
+        XFRM_LOOKUP_ICMP = 1 << 1,
 };
 
 struct flowi;