> -----Original Message----- > From: Harout Hedeshian [mailto:harouth@xxxxxxxxxxxxxx] > Sent: Monday, June 15, 2015 11:42 AM > To: 'Pablo Neira Ayuso' > Cc: 'netfilter-devel@xxxxxxxxxxxxxxx'; 'Lorenzo Colitti' > Subject: RE: [PATCH nf-next] netfilter: xt_socket: add > XT_SOCKET_MATCHSOCKMARK flag and mark fields > > > > > -----Original Message----- > > From: Pablo Neira Ayuso [mailto:pablo@xxxxxxxxxxxxx] > > Sent: Monday, June 15, 2015 10:23 AM > > To: Harout Hedeshian > > Cc: netfilter-devel@xxxxxxxxxxxxxxx; Lorenzo Colitti > > Subject: Re: [PATCH nf-next] netfilter: xt_socket: add > > XT_SOCKET_MATCHSOCKMARK flag and mark fields > > > > On Fri, Jun 12, 2015 at 04:39:55PM -0600, Harout Hedeshian wrote: > > > xt_socket is useful for matching sockets with IP_TRANSPARENT and > > > taking some action on the matching packets. However, it lacks the > > > ability to match only a small subset of transparent sockets. > > > > > > Suppose there are 2 applications, each with its own set of > > > transparent sockets. The first application wants all matching > > > packets dropped, while the second application wants them forwarded > somewhere else. > > > > > > Add the ability to match sockets based on the socket mark. > > > > > > Now the 2 hypothetical applications can differentiate their sockets > > > based on a mark value set with SO_MARK. > > > > > > iptables -t mangle -I PREROUTING -m socket --transparent --mark 10 > > > -J > > > act1 iptables -t mangle -I PREROUTING -m socket --transparent --mark > > > 11 -J act2 > > > > Wouldn't it be better to restore the sk_mark to skb->mark? I mean: > > > > iptables -t mangle -I PREROUTING \ > > -m socket --transparent --restore-skmark -j myskchain > > > > Thus, you can use -m mark from the 'myskchain' without having to fetch > > and inspect the sk over and over again as it happens with this > > extension. > > Yes, I think that can work. Let me try that out and I'll submit a new > patch. Actually, on second thought, I'm not so sure. This socket lookup is happening as part of a match operation in xt_socket.c. >From x_tables.h, I can see that match functions are not supposed to modify the skb: struct xt_match{ ... bool (*match)(const struct sk_buff *skb, struct xt_action_param *); In that case, would this even be valid? -m socket --transparent --restore-skmark Keeping in mind --restore-skmark is happening as part of -m socket I would think we would need a whole new target to handle something like this: iptables -t mangle -I PREROUTING -m socket --transparent --no-wildcard -j SOCKET --restore-skmark Since the target invocation would be separate, we would need a second socket lookup? Seems perhaps a little overkill... Harout -- To unsubscribe from this list: send the line "unsubscribe netfilter-devel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
