net: rds: Use address family to designate IPv4 or IPv6 addresses

net: rds: Use address family to designate IPv4 or IPv6 addresses

The condition to interpret the supplied address in
rds_cancel_sent_to() was the length of the supplied user-data. We need
to tighten the API here to the extent possible, subject to SKGXP
passing in sizeof(struct sockaddr_storage) as the optlen, independent
of the actual address size.

We will 1) make sure the data passed in to the kernel is "big enough",
2) that the address is either AF_INET or AF_INET6, and 3) that the
bound address is ipv6_addr_v4mapped() in the AF_INET case and not in
the AF_INET6 case.

Orabug: 28720071

Signed-off-by: Håkon Bugge <haakon.bugge@oracle.com>
Reviewed-by: Darren Kenny <darren.kenny@oracle.com>