Messages in this thread | | | Date | Thu, 27 Sep 2018 13:46:29 -0700 | From | Guenter Roeck <> | Subject | Re: [PATCH] netfilter: check if the socket netns is correct. |
| |
Hi Flavio,
On Wed, Jun 27, 2018 at 10:34:25AM -0300, Flavio Leitner wrote: > Netfilter assumes that if the socket is present in the skb, then > it can be used because that reference is cleaned up while the skb > is crossing netns. > > We want to change that to preserve the socket reference in a future > patch, so this is a preparation updating netfilter to check if the > socket netns matches before use it. > > Signed-off-by: Flavio Leitner <fbl@redhat.com> > Acked-by: Florian Westphal <fw@strlen.de> > Signed-off-by: David S. Miller <davem@davemloft.net> > --- ... > --- a/net/netfilter/xt_socket.c > +++ b/net/netfilter/xt_socket.c > @@ -56,8 +56,12 @@ socket_match(const struct sk_buff *skb, struct xt_action_param *par, > struct sk_buff *pskb = (struct sk_buff *)skb; > struct sock *sk = skb->sk; > > + if (!net_eq(xt_net(par), sock_net(sk))) > + sk = NULL; > +
I am having trouble with this code. With CONFIG_NET_NS enabled, it crashes for me in read_pnet() because sk is NULL.
> if (!sk) > sk = nf_sk_lookup_slow_v4(xt_net(par), skb, xt_in(par));
The old code seems to suggest that sk == NULL was possible.
I see the problem with the Chrome OS kernel rebased to v4.19-rc5, so I can not guarantee that this really an upstream problem. The change seems odd, though. Are you sure that it is not (or, rather, no longer) necessary to check if sk == NULL before dereferencing it in sock_net() ?
> + > if (sk) { > bool wildcard; > bool transparent = true; > @@ -113,8 +117,12 @@ socket_mt6_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par) > struct sk_buff *pskb = (struct sk_buff *)skb; > struct sock *sk = skb->sk; > > + if (!net_eq(xt_net(par), sock_net(sk))) > + sk = NULL; > + Same here.
> if (!sk) > sk = nf_sk_lookup_slow_v6(xt_net(par), skb, xt_in(par)); > + > if (sk) { > bool wildcard; > bool transparent = true;
Thanks, Guenter
| |