Re: [PATCH] net-ipv6: add support for sockopt(SOL_IPV6, IPV6_FREEBIND)

[David Miller <davem@davemloft.net>]

From: Maciej Żenczykowski <zenczykowski@gmail.com>
Date: Tue, 26 Sep 2017 21:32:42 -0700

> From: Maciej Żenczykowski <maze@google.com>
> 
> So far we've been relying on sockopt(SOL_IP, IP_FREEBIND) being usable
> even on IPv6 sockets.
> 
> However, it turns out it is perfectly reasonable to want to set freebind
> on an AF_INET6 SOCK_RAW socket - but there is no way to set any SOL_IP
> socket option on such a socket (they're all blindly errored out).
> 
> One use case for this is to allow spoofing src ip on a raw socket
> via sendmsg cmsg.
> 
> Tested:
>   built, and booted
>   # python
>   >>> import socket
>   >>> SOL_IP = socket.SOL_IP
>   >>> SOL_IPV6 = socket.IPPROTO_IPV6
>   >>> IP_FREEBIND = 15
>   >>> IPV6_FREEBIND = 78
>   >>> s = socket.socket(socket.AF_INET6, socket.SOCK_DGRAM, 0)
>   >>> s.getsockopt(SOL_IP, IP_FREEBIND)
>   0
>   >>> s.getsockopt(SOL_IPV6, IPV6_FREEBIND)
>   0
>   >>> s.setsockopt(SOL_IPV6, IPV6_FREEBIND, 1)
>   >>> s.getsockopt(SOL_IP, IP_FREEBIND)
>   1
>   >>> s.getsockopt(SOL_IPV6, IPV6_FREEBIND)
>   1
> 
> Signed-off-by: Maciej Żenczykowski <maze@google.com>

Applied to net-next, thanks.