Adding IP(v6) address with scope link creates global address

[Andreas Henriksson <andreas@fatal.se>]

Hello!

"Jedasothi" reported problems setting scope with iproute on newly added
ipv6 addresses in:
https://bugs.launchpad.net/ubuntu/+source/iproute/+bug/487745

> To reproduce bug run
> ip addr add '::4/64' scope link dev eth0
>
> This results in a line seen with
> ip addr show eth0
> inet6 ::4/64 scope global tentative
>
> The label "global" is seen instead of "link".

This works for me on ipv4 and seems to be only a problem with ipv6.

I think this is a kernel bug. The scope seems to be passed into the
kernel via netlink as specified on the command line.

Looking at the kernel, inet6_rtm_newaddr [1] calls inet6_addr_add [2]
without passing the ifa_scope struct member and then the scope is
generated from the address within the inet6_addr_add function.

It would be nice if someone could verify this and while at it
also whip up a patch and forward to the right person. ;)

[1]: http://lxr.linux.no/#linux+v2.6.31/net/ipv6/addrconf.c#L3263
[2]: http://lxr.linux.no/#linux+v2.6.31/net/ipv6/addrconf.c#L2081

-- 
Andreas Henriksson