Re: [PATCH 1/1] netfilter: ctnetlink: don't permit ct creation with random tuple

[Florian Westphal <fw@strlen.de>]

Pablo Neira Ayuso <pablo@netfilter.org> wrote:
> On Tue, Feb 12, 2013 at 10:22:38AM +0100, Florian Westphal wrote:
> > Userspace can cause kernel panic by not specifying orig/reply
> > tuple: kernel will create a tuple with random stack values.
> > 
> > Problem is that tuple.dst.dir will be random, too, which
> > causes nf_ct_tuplehash_to_ctrack() to return garbage.

[..]

> > diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
> > index 7bbfb3d..e592281 100644
> > --- a/net/netfilter/nf_conntrack_netlink.c
> > +++ b/net/netfilter/nf_conntrack_netlink.c
> > @@ -1596,6 +1596,9 @@ ctnetlink_new_conntrack(struct sock *ctnl, struct sk_buff *skb,
> >  		if (nlh->nlmsg_flags & NLM_F_CREATE) {
> >  			enum ip_conntrack_events events;
> >  
> > +			if (!cda[CTA_TUPLE_ORIG] ||
> > +			    !cda[CTA_TUPLE_REPLY])
> > +				return -EINVAL;
> 
> I think that needs to be && instead of ||.

Uh, maybe I'm too low on caffeine, but when a new conntrack
is to be created, shouldn't userspace have to specify
_both_ ORIG and REPLY?