1 files changed, 288 insertions, 0 deletions

diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
new file mode 100644
index 00000000..1bdfea35
--- /dev/null
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -0,0 +1,288 @@
+/* Helper handling for netfilter. */
+
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
+ * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#include <linux/types.h>
+#include <linux/netfilter.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/vmalloc.h>
+#include <linux/stddef.h>
+#include <linux/random.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+#include <linux/rculist.h>
+#include <linux/rtnetlink.h>
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_l3proto.h>
+#include <net/netfilter/nf_conntrack_l4proto.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_core.h>
+#include <net/netfilter/nf_conntrack_extend.h>
+
+static DEFINE_MUTEX(nf_ct_helper_mutex);
+static struct hlist_head *nf_ct_helper_hash __read_mostly;
+static unsigned int nf_ct_helper_hsize __read_mostly;
+static unsigned int nf_ct_helper_count __read_mostly;
+
+
+/* Stupid hash, but collision free for the default registrations of the
+ * helpers currently in the kernel. */
+static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
+{
+	return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
+		(__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
+}
+
+static struct nf_conntrack_helper *
+__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
+{
+	struct nf_conntrack_helper *helper;
+	struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
+	struct hlist_node *n;
+	unsigned int h;
+
+	if (!nf_ct_helper_count)
+		return NULL;
+
+	h = helper_hash(tuple);
+	hlist_for_each_entry_rcu(helper, n, &nf_ct_helper_hash[h], hnode) {
+		if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
+			return helper;
+	}
+	return NULL;
+}
+
+struct nf_conntrack_helper *
+__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
+{
+	struct nf_conntrack_helper *h;
+	struct hlist_node *n;
+	unsigned int i;
+
+	for (i = 0; i < nf_ct_helper_hsize; i++) {
+		hlist_for_each_entry_rcu(h, n, &nf_ct_helper_hash[i], hnode) {
+			if (!strcmp(h->name, name) &&
+			    h->tuple.src.l3num == l3num &&
+			    h->tuple.dst.protonum == protonum)
+				return h;
+		}
+	}
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
+
+struct nf_conntrack_helper *
+nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
+{
+	struct nf_conntrack_helper *h;
+
+	h = __nf_conntrack_helper_find(name, l3num, protonum);
+#ifdef CONFIG_MODULES
+	if (h == NULL) {
+		if (request_module("nfct-helper-%s", name) == 0)
+			h = __nf_conntrack_helper_find(name, l3num, protonum);
+	}
+#endif
+	if (h != NULL && !try_module_get(h->me))
+		h = NULL;
+
+	return h;
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
+
+struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
+{
+	struct nf_conn_help *help;
+
+	help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp);
+	if (help)
+		INIT_HLIST_HEAD(&help->expectations);
+	else
+		pr_debug("failed to add helper extension area");
+	return help;
+}
+EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
+
+int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
+			      gfp_t flags)
+{
+	struct nf_conntrack_helper *helper = NULL;
+	struct nf_conn_help *help;
+	int ret = 0;
+
+	if (tmpl != NULL) {
+		help = nfct_help(tmpl);
+		if (help != NULL)
+			helper = help->helper;
+	}
+
+	help = nfct_help(ct);
+	if (helper == NULL)
+		helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
+	if (helper == NULL) {
+		if (help)
+			rcu_assign_pointer(help->helper, NULL);
+		goto out;
+	}
+
+	if (help == NULL) {
+		help = nf_ct_helper_ext_add(ct, flags);
+		if (help == NULL) {
+			ret = -ENOMEM;
+			goto out;
+		}
+	} else {
+		memset(&help->help, 0, sizeof(help->help));
+	}
+
+	rcu_assign_pointer(help->helper, helper);
+out:
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
+
+static inline int unhelp(struct nf_conntrack_tuple_hash *i,
+			 const struct nf_conntrack_helper *me)
+{
+	struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
+	struct nf_conn_help *help = nfct_help(ct);
+
+	if (help && rcu_dereference_protected(
+			help->helper,
+			lockdep_is_held(&nf_conntrack_lock)
+			) == me) {
+		nf_conntrack_event(IPCT_HELPER, ct);
+		rcu_assign_pointer(help->helper, NULL);
+	}
+	return 0;
+}
+
+void nf_ct_helper_destroy(struct nf_conn *ct)
+{
+	struct nf_conn_help *help = nfct_help(ct);
+	struct nf_conntrack_helper *helper;
+
+	if (help) {
+		rcu_read_lock();
+		helper = rcu_dereference(help->helper);
+		if (helper && helper->destroy)
+			helper->destroy(ct);
+		rcu_read_unlock();
+	}
+}
+
+int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
+{
+	unsigned int h = helper_hash(&me->tuple);
+
+	BUG_ON(me->expect_policy == NULL);
+	BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
+	BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
+
+	mutex_lock(&nf_ct_helper_mutex);
+	hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
+	nf_ct_helper_count++;
+	mutex_unlock(&nf_ct_helper_mutex);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
+
+static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
+					     struct net *net)
+{
+	struct nf_conntrack_tuple_hash *h;
+	struct nf_conntrack_expect *exp;
+	const struct hlist_node *n, *next;
+	const struct hlist_nulls_node *nn;
+	unsigned int i;
+
+	/* Get rid of expectations */
+	for (i = 0; i < nf_ct_expect_hsize; i++) {
+		hlist_for_each_entry_safe(exp, n, next,
+					  &net->ct.expect_hash[i], hnode) {
+			struct nf_conn_help *help = nfct_help(exp->master);
+			if ((rcu_dereference_protected(
+					help->helper,
+					lockdep_is_held(&nf_conntrack_lock)
+					) == me || exp->helper == me) &&
+			    del_timer(&exp->timeout)) {
+				nf_ct_unlink_expect(exp);
+				nf_ct_expect_put(exp);
+			}
+		}
+	}
+
+	/* Get rid of expecteds, set helpers to NULL. */
+	hlist_nulls_for_each_entry(h, nn, &net->ct.unconfirmed, hnnode)
+		unhelp(h, me);
+	for (i = 0; i < net->ct.htable_size; i++) {
+		hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode)
+			unhelp(h, me);
+	}
+}
+
+void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
+{
+	struct net *net;
+
+	mutex_lock(&nf_ct_helper_mutex);
+	hlist_del_rcu(&me->hnode);
+	nf_ct_helper_count--;
+	mutex_unlock(&nf_ct_helper_mutex);
+
+	/* Make sure every nothing is still using the helper unless its a
+	 * connection in the hash.
+	 */
+	synchronize_rcu();
+
+	rtnl_lock();
+	spin_lock_bh(&nf_conntrack_lock);
+	for_each_net(net)
+		__nf_conntrack_helper_unregister(me, net);
+	spin_unlock_bh(&nf_conntrack_lock);
+	rtnl_unlock();
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
+
+static struct nf_ct_ext_type helper_extend __read_mostly = {
+	.len	= sizeof(struct nf_conn_help),
+	.align	= __alignof__(struct nf_conn_help),
+	.id	= NF_CT_EXT_HELPER,
+};
+
+int nf_conntrack_helper_init(void)
+{
+	int err;
+
+	nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
+	nf_ct_helper_hash = nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
+	if (!nf_ct_helper_hash)
+		return -ENOMEM;
+
+	err = nf_ct_extend_register(&helper_extend);
+	if (err < 0)
+		goto err1;
+
+	return 0;
+
+err1:
+	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
+	return err;
+}
+
+void nf_conntrack_helper_fini(void)
+{
+	nf_ct_extend_unregister(&helper_extend);
+	nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
+}