[PATCH net v2] ipv6: Allow IPv4-mapped address as next-hop

[PATCH net v2] 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>
---
v2 honoring minimum 1000 ft vertical separation between Thunderbird and patches (fixed whitespace issues)

 net/ipv6/route.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index 1b57e11..86bdb02 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1995,8 +1995,11 @@ static struct rt6_info *ip6_route_info_create(struct fib6_config *cfg)
 			   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) {
-- 
1.8.1.4

Re: [PATCH net v2] ipv6: Allow IPv4-mapped address as next-hop

[David Miller]

From: Erik Nordmark <nordmark@arista.com>
Date: Sat,  3 Dec 2016 20:57:09 -0800

> 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>

Applied to net-next, thanks.

Re: [PATCH net v2] ipv6: Allow IPv4-mapped address as next-hop

[Erik Nordmark]

On 12/5/16 11:52 AM, David Miller wrote:
> From: Erik Nordmark <nordmark@arista.com>
> Date: Sat,  3 Dec 2016 20:57:09 -0800
>
>> 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>
> Applied to net-next, thanks.
>
Thanks, especially for moving it from net to net-next.

I guess I don't fully understand what is considered a bug fix for net as 
opposed to new stuff for net-next. Is the former mostly for regressions 
and serious bugs? This was a fix for a bug that's been there since the 
beginning of IPv6 time AFAICT.


   Erik