[PATCH net] ipv6: Allow IPv4-mapped address as next-hop

[PATCH net] ipv6: Allow IPv4-mapped address as next-hop

[Erik Nordmark]

Made kernel accept IPv6 routes with IPv4-mapped address as next-hop.

It is possible to configure IP interfaces with IPv4-mapped addresses, and
one can add IPv6 routes for IPv4-mapped destinations/prefixes, yet prior
to this fix the kernel returned an EINVAL when attempting to add an IPv6
route with an IPv4-mapped address as a nexthop/gateway.

RFC 4798 (a proposed standard RFC) uses IPv4-mapped addresses as nexthops,
thus in order to support that type of address configuration the kernel
needs to allow IPv4-mapped addresses as nexthops.

Signed-off-by: Erik Nordmark <nordmark@arista.com>
Signed-off-by: Bob Gilligan <gilligan@arista.com>"

Index: net/net/ipv6/route.c
===================================================================
--- net.orig/net/ipv6/route.c
+++ net/net/ipv6/route.c
@@ -1995,8 +1995,11 @@ static struct rt6_info *ip6_route_info_c
  			   It is very good, but in some (rare!) circumstances
  			   (SIT, PtP, NBMA NOARP links) it is handy to allow
  			   some exceptions. --ANK
+			   We allow IPv4-mapped nexthops to support RFC4798-type
+			   addressing
  			 */
-			if (!(gwa_type & IPV6_ADDR_UNICAST))
+			if (!(gwa_type & (IPV6_ADDR_UNICAST |
+					  IPV6_ADDR_MAPPED)))
  				goto out;
  
  			if (cfg->fc_table) {

Re: [PATCH net] ipv6: Allow IPv4-mapped address as next-hop

[David Miller]

From: Erik Nordmark <nordmark@arista.com>
Date: Mon, 28 Nov 2016 15:27:05 -0800

> @@ -1995,8 +1995,11 @@ static struct rt6_info *ip6_route_info_c
>  			   It is very good, but in some (rare!) circumstances
>  			   (SIT, PtP, NBMA NOARP links) it is handy to allow
>  			   some exceptions. --ANK
> + We allow IPv4-mapped nexthops to support RFC4798-type
> +			   addressing
>  			 */

This is definitely not indented and formatted correctly, please fix.