ipv6: fib: Add offload indication to routes

Allow user space applications to see which routes are offloaded and
which aren't by setting the RTNH_F_OFFLOAD flag when dumping them.

To be consistent with IPv4, offload indication is provided on a
per-nexthop basis.
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/uapi/linux/ipv6_route.h

@@ -35,6 +35,7 @@
 #define RTF_PREF(pref)	((pref) << 27)
 #define RTF_PREF_MASK	0x18000000
 
+#define RTF_OFFLOAD	0x20000000	/* offloaded route		*/
 #define RTF_PCPU	0x40000000	/* read-only: can not be set by user */
 #define RTF_LOCAL	0x80000000
 

net/ipv6/route.c

@@ -1820,6 +1820,11 @@ static struct rt6_info *ip6_route_info_create(struct fib6_config *cfg,
 		goto out;
 	}
 
+	if (cfg->fc_flags & RTF_OFFLOAD) {
+		NL_SET_ERR_MSG(extack, "Userspace can not set RTF_OFFLOAD");
+		goto out;
+	}
+
 	if (cfg->fc_dst_len > 128) {
 		NL_SET_ERR_MSG(extack, "Invalid prefix length");
 		goto out;
@@ -3327,6 +3332,9 @@ static int rt6_nexthop_info(struct sk_buff *skb, struct rt6_info *rt,
 			goto nla_put_failure;
 	}
 
+	if (rt->rt6i_flags & RTF_OFFLOAD)
+		*flags |= RTNH_F_OFFLOAD;
+
 	/* not needed for multipath encoding b/c it has a rtnexthop struct */
 	if (!skip_oif && rt->dst.dev &&
 	    nla_put_u32(skb, RTA_OIF, rt->dst.dev->ifindex))