netfilter: nf_conntrack: add efficient mark to zone mapping

This work adds the possibility of deriving the zone id from the skb->mark
field in a scalable manner. This allows for having only a single template
serving hundreds/thousands of different zones, for example, instead of the
need to have one match for each zone as an extra CT jump target.

Note that we'd need to have this information attached to the template as at
the time when we're trying to lookup a possible ct object, we already need
to know zone information for a possible match when going into
__nf_conntrack_find_get(). This work provides a minimal implementation for
a possible mapping.

In order to not add/expose an extra ct->status bit, the zone structure has
been extended to carry a flag for deriving the mark.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 16 insertions, 34 deletions

diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c
index acc06222ce6a..48521d62c672 100644
--- a/net/netfilter/nf_conntrack_core.c
+++ b/net/netfilter/nf_conntrack_core.c
@@ -301,25 +301,15 @@ struct nf_conn *nf_ct_tmpl_alloc(struct net *net,
 	tmpl->status = IPS_TEMPLATE;
 	write_pnet(&tmpl->ct_net, net);
 
-#ifdef CONFIG_NF_CONNTRACK_ZONES
-	if (zone) {
-		struct nf_conntrack_zone *nf_ct_zone;
-
-		nf_ct_zone = nf_ct_ext_add(tmpl, NF_CT_EXT_ZONE, GFP_ATOMIC);
-		if (!nf_ct_zone)
-			goto out_free;
-		nf_ct_zone->id = zone->id;
-		nf_ct_zone->dir = zone->dir;
-	}
-#endif
+	if (nf_ct_zone_add(tmpl, flags, zone) < 0)
+		goto out_free;
+
 	atomic_set(&tmpl->ct_general.use, 0);
 
 	return tmpl;
-#ifdef CONFIG_NF_CONNTRACK_ZONES
 out_free:
 	kfree(tmpl);
 	return NULL;
-#endif
 }
 EXPORT_SYMBOL_GPL(nf_ct_tmpl_alloc);
 
@@ -850,10 +840,9 @@ __nf_conntrack_alloc(struct net *net,
 	 * SLAB_DESTROY_BY_RCU.
 	 */
 	ct = kmem_cache_alloc(net->ct.nf_conntrack_cachep, gfp);
-	if (ct == NULL) {
-		atomic_dec(&net->ct.count);
-		return ERR_PTR(-ENOMEM);
-	}
+	if (ct == NULL)
+		goto out;
+
 	spin_lock_init(&ct->lock);
 	ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple = *orig;
 	ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode.pprev = NULL;
@@ -867,29 +856,20 @@ __nf_conntrack_alloc(struct net *net,
 	memset(&ct->__nfct_init_offset[0], 0,
 	       offsetof(struct nf_conn, proto) -
 	       offsetof(struct nf_conn, __nfct_init_offset[0]));
-#ifdef CONFIG_NF_CONNTRACK_ZONES
-	if (zone) {
-		struct nf_conntrack_zone *nf_ct_zone;
-
-		nf_ct_zone = nf_ct_ext_add(ct, NF_CT_EXT_ZONE, GFP_ATOMIC);
-		if (!nf_ct_zone)
-			goto out_free;
-		nf_ct_zone->id = zone->id;
-		nf_ct_zone->dir = zone->dir;
-	}
-#endif
+
+	if (zone && nf_ct_zone_add(ct, GFP_ATOMIC, zone) < 0)
+		goto out_free;
+
 	/* Because we use RCU lookups, we set ct_general.use to zero before
 	 * this is inserted in any list.
 	 */
 	atomic_set(&ct->ct_general.use, 0);
 	return ct;
-
-#ifdef CONFIG_NF_CONNTRACK_ZONES
 out_free:
-	atomic_dec(&net->ct.count);
 	kmem_cache_free(net->ct.nf_conntrack_cachep, ct);
+out:
+	atomic_dec(&net->ct.count);
 	return ERR_PTR(-ENOMEM);
-#endif
 }
 
 struct nf_conn *nf_conntrack_alloc(struct net *net,
@@ -937,6 +917,7 @@ init_conntrack(struct net *net, struct nf_conn *tmpl,
 	struct nf_conntrack_expect *exp = NULL;
 	const struct nf_conntrack_zone *zone;
 	struct nf_conn_timeout *timeout_ext;
+	struct nf_conntrack_zone tmp;
 	unsigned int *timeouts;
 
 	if (!nf_ct_invert_tuple(&repl_tuple, tuple, l3proto, l4proto)) {
@@ -944,7 +925,7 @@ init_conntrack(struct net *net, struct nf_conn *tmpl,
 		return NULL;
 	}
 
-	zone = nf_ct_zone_tmpl(tmpl);
+	zone = nf_ct_zone_tmpl(tmpl, skb, &tmp);
 	ct = __nf_conntrack_alloc(net, zone, tuple, &repl_tuple, GFP_ATOMIC,
 				  hash);
 	if (IS_ERR(ct))
@@ -1042,6 +1023,7 @@ resolve_normal_ct(struct net *net, struct nf_conn *tmpl,
 	const struct nf_conntrack_zone *zone;
 	struct nf_conntrack_tuple tuple;
 	struct nf_conntrack_tuple_hash *h;
+	struct nf_conntrack_zone tmp;
 	struct nf_conn *ct;
 	u32 hash;
 
@@ -1053,7 +1035,7 @@ resolve_normal_ct(struct net *net, struct nf_conn *tmpl,
 	}
 
 	/* look for tuple match */
-	zone = nf_ct_zone_tmpl(tmpl);
+	zone = nf_ct_zone_tmpl(tmpl, skb, &tmp);
 	hash = hash_conntrack_raw(&tuple);
 	h = __nf_conntrack_find_get(net, zone, &tuple, hash);
 	if (!h) {