Re: [PATCH RESEND] netfilter: bridge: unshare bridge info before change it

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

On Wed, Nov 19, 2014 at 10:11:25AM +0800, Gao feng wrote:
> On 11/19/2014 02:34 AM, Pablo Neira Ayuso wrote:
> > On Mon, Nov 17, 2014 at 01:48:43PM +0800, Gao feng wrote:
> >> diff --git a/net/bridge/br_netfilter.c b/net/bridge/br_netfilter.c
> >> index 1a4f32c..b4612b9 100644
> >> --- a/net/bridge/br_netfilter.c
> >> +++ b/net/bridge/br_netfilter.c
> >> @@ -653,7 +643,11 @@ static int br_nf_forward_finish(struct sk_buff *skb)
> >>  		in = nf_bridge->physindev;
> >>  		if (nf_bridge->mask & BRNF_PKT_TYPE) {
> >>  			skb->pkt_type = PACKET_OTHERHOST;
> >> -			nf_bridge->mask ^= BRNF_PKT_TYPE;
> >> +
> >> +			if (!nf_bridge_unset_mask(skb, BRNF_PKT_TYPE)) {
> >> +				kfree_skb(skb);
> >> +				return 0;
> >> +			}
> > 
> > This can now release the packet and, thus, drop it.
> > 
> > However, br_nf_forward_ip() always returns NF_STOLEN.
> > 
> > Could you revisit the error paths and confirm they are correct?
> 
> Since br_nf_forward_ip() returns NF_STOLEN, br_nf_forward_finish should make
> sure this skb will be released. if unser_mask for this skb is failed, we free
> it. if unset successed, the hooks on NF_BR_FORWARD or br_forward_finish will
> free this skb.

OK, but I think this should return NF_DROP instead of NF_STOLEN so you
don't explicitly need to kfree_skb it.