mpls: allow TTL propagation to IP packets to be configured
Provide the ability to control on a per-route basis whether the TTL
value from an MPLS packet is propagated to an IPv4/IPv6 packet when
the last label is popped as per the theoretical model in RFC 3443
through a new route attribute, RTA_TTL_PROPAGATE which can be 0 to
mean disable propagation and 1 to mean enable propagation.
In order to provide the ability to change the behaviour for packets
arriving with IPv4/IPv6 Explicit Null labels and to provide an easy
way for a user to change the behaviour for all existing routes without
having to reprogram them, a global knob is provided. This is done
through the addition of a new per-namespace sysctl,
"net.mpls.ip_ttl_propagate", which defaults to enabled. If the
per-route attribute is set (either enabled or disabled) then it
overrides the global configuration.
Signed-off-by: Robert Shearman <rshearma@brocade.com>
Acked-by: David Ahern <dsa@cumulusnetworks.com>
Tested-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/mpls/internal.h b/net/mpls/internal.h
index 76360d8..62928d8 100644
--- a/net/mpls/internal.h
+++ b/net/mpls/internal.h
@@ -90,6 +90,12 @@ struct mpls_nh { /* next hop label forwarding entry */
u8 nh_via_table;
};
+enum mpls_ttl_propagation {
+ MPLS_TTL_PROP_DEFAULT,
+ MPLS_TTL_PROP_ENABLED,
+ MPLS_TTL_PROP_DISABLED,
+};
+
/* The route, nexthops and vias are stored together in the same memory
* block:
*
@@ -116,6 +122,7 @@ struct mpls_route { /* next hop label forwarding entry */
u8 rt_protocol;
u8 rt_payload_type;
u8 rt_max_alen;
+ u8 rt_ttl_propagate;
unsigned int rt_nhn;
unsigned int rt_nhn_alive;
struct mpls_nh rt_nh[0];