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: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/netfilter/nfnetlink_conntrack.h b/include/linux/netfilter/nfnetlink_conntrack.h
index debf1ae..d498a44 100644
--- a/include/linux/netfilter/nfnetlink_conntrack.h
+++ b/include/linux/netfilter/nfnetlink_conntrack.h
@@ -43,6 +43,7 @@
CTA_ZONE,
CTA_SECCTX,
CTA_TIMESTAMP,
+ CTA_MARK_MASK,
__CTA_MAX
};
#define CTA_MAX (__CTA_MAX - 1)
diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c
index 61f7feb..28d0312 100644
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -691,9 +691,18 @@
{
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 @@
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 @@
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 @@
[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 @@
.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);
}