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Commit 0f298a28 authored by Pablo Neira Ayuso's avatar Pablo Neira Ayuso Committed by David S. Miller
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netfilter: ctnetlink: support kernel-space dump filtering by ctmark 



This patch adds CTA_MARK_MASK which, together with CTA_MARK, allows
you to selectively send conntrack entries to user-space by
returning those that match mark & mask.

With this, we can save cycles in the building and the parsing of
the entries that may be later on filtered out in user-space by using
the ctmark & mask.

Signed-off-by: default avatarPablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 7175c883

include/linux/netfilter/nfnetlink_conntrack.h

+1 −0
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ enum ctattr_type { 
	CTA_ZONE,

	CTA_SECCTX,

	CTA_TIMESTAMP,

	CTA_MARK_MASK,

	__CTA_MAX

};

#define CTA_MAX (__CTA_MAX - 1)

net/netfilter/nf_conntrack_netlink.c

+34 −1
Original line number Diff line number Diff line
@@ -691,9 +691,18 @@ static int ctnetlink_done(struct netlink_callback *cb) 
{

	if (cb->args[1])

		nf_ct_put((struct nf_conn *)cb->args[1]);

	if (cb->data)

		kfree(cb->data);

	return 0;

}



struct ctnetlink_dump_filter {

	struct {

		u_int32_t val;

		u_int32_t mask;

	} mark;

};



static int

ctnetlink_dump_table(struct sk_buff *skb, struct netlink_callback *cb)

{
@@ -703,7 +712,9 @@ ctnetlink_dump_table(struct sk_buff *skb, struct netlink_callback *cb) 
	struct hlist_nulls_node *n;

	struct nfgenmsg *nfmsg = nlmsg_data(cb->nlh);

	u_int8_t l3proto = nfmsg->nfgen_family;



#ifdef CONFIG_NF_CONNTRACK_MARK

	const struct ctnetlink_dump_filter *filter = cb->data;

#endif

	spin_lock_bh(&nf_conntrack_lock);

	last = (struct nf_conn *)cb->args[1];

	for (; cb->args[0] < net->ct.htable_size; cb->args[0]++) {
@@ -723,6 +734,12 @@ restart: 
					continue;

				cb->args[1] = 0;

			}

#ifdef CONFIG_NF_CONNTRACK_MARK

			if (filter && !((ct->mark & filter->mark.mask) ==

					filter->mark.val)) {

				continue;

			}

#endif

			if (ctnetlink_fill_info(skb, NETLINK_CB(cb->skb).pid,

						cb->nlh->nlmsg_seq,

						NFNL_MSG_TYPE(
@@ -894,6 +911,7 @@ static const struct nla_policy ct_nla_policy[CTA_MAX+1] = { 
	[CTA_NAT_DST]		= { .type = NLA_NESTED },

	[CTA_TUPLE_MASTER]	= { .type = NLA_NESTED },

	[CTA_ZONE]		= { .type = NLA_U16 },

	[CTA_MARK_MASK]		= { .type = NLA_U32 },

};



static int
@@ -982,6 +1000,21 @@ ctnetlink_get_conntrack(struct sock *ctnl, struct sk_buff *skb, 
			.dump = ctnetlink_dump_table,

			.done = ctnetlink_done,

		};

#ifdef CONFIG_NF_CONNTRACK_MARK

		if (cda[CTA_MARK] && cda[CTA_MARK_MASK]) {

			struct ctnetlink_dump_filter *filter;



			filter = kzalloc(sizeof(struct ctnetlink_dump_filter),

					 GFP_ATOMIC);

			if (filter == NULL)

				return -ENOMEM;



			filter->mark.val = ntohl(nla_get_be32(cda[CTA_MARK]));

			filter->mark.mask =

				ntohl(nla_get_be32(cda[CTA_MARK_MASK]));

			c.data = filter;

		}

#endif

		return netlink_dump_start(ctnl, skb, nlh, &c);

	}