[NETFILTER]: nf_conntrack_expect: support inactive expectations

This is useful for the SIP helper and signalling expectations.
We don't want to create a full-blown expectation with a wildcard
as source based on a single UDP packet, but need to know the
final port anyways. With inactive expectations we can register
the expectation and reserve the tuple, but wait for confirmation
from the registrar before activating it.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/netfilter/nf_conntrack_expect.h

@@ -54,6 +54,7 @@ struct nf_conntrack_expect
 };
 
 #define NF_CT_EXPECT_PERMANENT	0x1
+#define NF_CT_EXPECT_INACTIVE	0x2
 
 int nf_conntrack_expect_init(void);
 void nf_conntrack_expect_fini(void);

net/netfilter/nf_conntrack_expect.c

@@ -126,9 +126,21 @@ EXPORT_SYMBOL_GPL(nf_ct_expect_find_get);
 struct nf_conntrack_expect *
 nf_ct_find_expectation(const struct nf_conntrack_tuple *tuple)
 {
-	struct nf_conntrack_expect *exp;
+	struct nf_conntrack_expect *i, *exp = NULL;
+	struct hlist_node *n;
+	unsigned int h;
+
+	if (!nf_ct_expect_count)
+		return NULL;
 
-	exp = __nf_ct_expect_find(tuple);
+	h = nf_ct_expect_dst_hash(tuple);
+	hlist_for_each_entry(i, n, &nf_ct_expect_hash[h], hnode) {
+		if (!(i->flags & NF_CT_EXPECT_INACTIVE) &&
+		    nf_ct_tuple_mask_cmp(tuple, &i->tuple, &i->mask)) {
+			exp = i;
+			break;
+		}
+	}
 	if (!exp)
 		return NULL;
 
@@ -460,6 +472,7 @@ static int exp_seq_show(struct seq_file *s, void *v)
 {
 	struct nf_conntrack_expect *expect;
 	struct hlist_node *n = v;
+	char *delim = "";
 
 	expect = hlist_entry(n, struct nf_conntrack_expect, hnode);
 
@@ -476,8 +489,12 @@ static int exp_seq_show(struct seq_file *s, void *v)
 		    __nf_ct_l4proto_find(expect->tuple.src.l3num,
 				       expect->tuple.dst.protonum));
 
-	if (expect->flags & NF_CT_EXPECT_PERMANENT)
-		seq_printf(s, "PERMANENT ");
+	if (expect->flags & NF_CT_EXPECT_PERMANENT) {
+		seq_printf(s, "PERMANENT");
+		delim = ",";
+	}
+	if (expect->flags & NF_CT_EXPECT_INACTIVE)
+		seq_printf(s, "%sINACTIVE", delim);
 
 	return seq_putc(s, '\n');
 }