[IPSEC]: Add XFRM_STATE_NOPMTUDISC flag
This patch adds the flag XFRM_STATE_NOPMTUDISC for xfrm states. It is
similar to the nopmtudisc on IPIP/GRE tunnels. It only has an effect
on IPv4 tunnel mode states. For these states, it will ensure that the
DF flag is always cleared.
This is primarily useful to work around ICMP blackholes.
In future this flag could also allow a larger MTU to be set within the
tunnel just like IPIP/GRE tunnels. This could be useful for short haul
tunnels where temporary fragmentation outside the tunnel is desired over
smaller fragments inside the tunnel.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Acked-by: James Morris <jmorris@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/pfkeyv2.h b/include/linux/pfkeyv2.h
index e6b5192..7240667 100644
--- a/include/linux/pfkeyv2.h
+++ b/include/linux/pfkeyv2.h
@@ -245,6 +245,7 @@
/* Security Association flags */
#define SADB_SAFLAGS_PFS 1
+#define SADB_SAFLAGS_NOPMTUDISC 0x20000000
#define SADB_SAFLAGS_DECAP_DSCP 0x40000000
#define SADB_SAFLAGS_NOECN 0x80000000