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

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Tue, Feb 12, 2013 at 01:43:28PM +0100, Florian Westphal wrote:
> 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?

You're right, it's me who is low on caffeine. Sorry.