Re: [PATCH 2/6] netlink: have netlink per-protocol bind function return an error code.
On 14/04/22, David Miller wrote:
From: Richard Guy Briggs <rgb(a)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.
The risk seems small, but I agree it is sloppy.
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.
Ok, done. This revision ends up being a bit cleaner than the previous
one because I've refactored out the unbind loop into netlink_unbind()
due to it needing to be called if the netlink_insert/autobind() fails as
well. In the factorization process I noticed that unrequested groups
were being unnecessarily unbound. It also provoked assigning the var
"groups" from "nladdr->nl_groups" making things easier to read.
Please make this change and resubmit this series, thanks.
Compiled and tested. New patchset to follow.
- RGB
--
Richard Guy Briggs <rbriggs(a)redhat.com>
Senior Software Engineer, Kernel Security, AMER ENG Base Operating Systems, Red Hat
Remote, Ottawa, Canada
Voice: +1.647.777.2635, Internal: (81) 32635, Alt: +1.613.693.0684x3545