Re: [PATCH 2/6] netlink: have netlink per-protocol bind function return an error code.

David Miller
2014-04-22T20:19:04Z

From: Richard Guy Briggs <rgb@redhat.com>
Date: Fri, 18 Apr 2014 13:34:06 -0400

> @@ -1449,6 +1453,26 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
> if (!nladdr->nl_groups && (nlk->groups == NULL || !(u32)nlk->groups[0]))
> return 0;
>
> + if (nlk->netlink_bind && nladdr->nl_groups) {
> + int i;
> +
> + for (i = 0; i < nlk->ngroups; i++) {
> + int undo;
> +
> + if (!test_bit(i, (long unsigned int *)&nladdr->nl_groups))
> + continue;
> + err = nlk->netlink_bind(i);
> + if (!err)
> + continue;
> + if (!nlk->portid)
> + netlink_remove(sk);
> + for (undo = 0; undo < i; undo++)
> + if (nlk->netlink_unbind)
> + nlk->netlink_unbind(undo);
> + return err;
> + }
> + }
> +

It took me a while to figure out why you need to do the netlink_remove() in
the error path.

I think it's really asking for trouble to allow the socket to have temporary
visibility if we end up signalling an error.

It seems safest if we only do the autobind/insert once we are absolutely
certain that the bind() will fully succeed. This means that you have to
do this bind validation loop before autobind/insert.

Please make this change and resubmit this series, thanks.