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 debf1aefd753cef4770c4249222f0bebe2cd0a5c..d498a4426ebfdd9002712b622cfc62b823fa6644 100644 (file)
--- a/include/linux/netfilter/nfnetlink_conntrack.h
+++ b/include/linux/netfilter/nfnetlink_conntrack.h
@@ -43,6 +43,7 @@ enum ctattr_type {
        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 61f7feb7932ba0290e817a15da557b679304a769..28d0312d890af22ff0ae0d229e0dbd6fc618e0be 100644 (file)
--- a/net/netfilter/nf_conntrack_netlink.c
+++ b/net/netfilter/nf_conntrack_netlink.c
@@ -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);
        }