netfilter: Add helper array register/unregister functions

Add nf_ct_helper_init(), nf_conntrack_helpers_register() and
nf_conntrack_helpers_unregister() functions to avoid repetitive
opencoded initialization in helpers.

This patch keeps an id parameter for nf_ct_helper_init() not to break
helper matching by name that has been inconsistently exposed to
userspace through ports, eg. ftp-2121, and through an incremental id,
eg. tftp-1.

Signed-off-by: Gao Feng <fgao@ikuai8.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 57 insertions, 0 deletions

diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
index a4294e949cdc07..b989b81ac15638 100644
--- a/net/netfilter/nf_conntrack_helper.c
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -465,6 +465,63 @@ restart:
 }
 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
 
+void nf_ct_helper_init(struct nf_conntrack_helper *helper,
+		       u16 l3num, u16 protonum, const char *name,
+		       u16 default_port, u16 spec_port, u32 id,
+		       const struct nf_conntrack_expect_policy *exp_pol,
+		       u32 expect_class_max, u32 data_len,
+		       int (*help)(struct sk_buff *skb, unsigned int protoff,
+				   struct nf_conn *ct,
+				   enum ip_conntrack_info ctinfo),
+		       int (*from_nlattr)(struct nlattr *attr,
+					  struct nf_conn *ct),
+		       struct module *module)
+{
+	helper->tuple.src.l3num = l3num;
+	helper->tuple.dst.protonum = protonum;
+	helper->tuple.src.u.all = htons(spec_port);
+	helper->expect_policy = exp_pol;
+	helper->expect_class_max = expect_class_max;
+	helper->data_len = data_len;
+	helper->help = help;
+	helper->from_nlattr = from_nlattr;
+	helper->me = module;
+
+	if (spec_port == default_port)
+		snprintf(helper->name, sizeof(helper->name), "%s", name);
+	else
+		snprintf(helper->name, sizeof(helper->name), "%s-%u", name, id);
+}
+EXPORT_SYMBOL_GPL(nf_ct_helper_init);
+
+int nf_conntrack_helpers_register(struct nf_conntrack_helper *helper,
+				  unsigned int n)
+{
+	unsigned int i;
+	int err = 0;
+
+	for (i = 0; i < n; i++) {
+		err = nf_conntrack_helper_register(&helper[i]);
+		if (err < 0)
+			goto err;
+	}
+
+	return err;
+err:
+	if (i > 0)
+		nf_conntrack_helpers_unregister(helper, i);
+	return err;
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_helpers_register);
+
+void nf_conntrack_helpers_unregister(struct nf_conntrack_helper *helper,
+				unsigned int n)
+{
+	while (n-- > 0)
+		nf_conntrack_helper_unregister(&helper[n]);
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_helpers_unregister);
+
 static struct nf_ct_ext_type helper_extend __read_mostly = {
 	.len	= sizeof(struct nf_conn_help),
 	.align	= __alignof__(struct nf_conn_help),