[NETFILTER]: nf_conntrack: split out helper handling

This patch splits out handling of helpers into its own file
nf_conntrack_helper.c

Signed-off-by: Martin Josefsson <gandalf@wlug.westbo.se>
Signed-off-by: Patrick McHardy <kaber@trash.net>

1 files changed, 151 insertions, 0 deletions

diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
new file mode 100644
index 000000000000..ca044875a561
--- /dev/null
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -0,0 +1,151 @@
+/* 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/slab.h>
+#include <linux/random.h>
+#include <linux/err.h>
+#include <linux/kernel.h>
+#include <linux/netdevice.h>
+
+#define ASSERT_READ_LOCK(x)
+#define ASSERT_WRITE_LOCK(x)
+
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_l3proto.h>
+#include <net/netfilter/nf_conntrack_protocol.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_core.h>
+
+static LIST_HEAD(helpers);
+
+struct nf_conntrack_helper *
+__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
+{
+	struct nf_conntrack_helper *h;
+
+	list_for_each_entry(h, &helpers, list) {
+		if (nf_ct_tuple_mask_cmp(tuple, &h->tuple, &h->mask))
+			return h;
+	}
+	return NULL;
+}
+
+struct nf_conntrack_helper *
+nf_ct_helper_find_get( const struct nf_conntrack_tuple *tuple)
+{
+	struct nf_conntrack_helper *helper;
+
+	/* need nf_conntrack_lock to assure that helper exists until
+	 * try_module_get() is called */
+	read_lock_bh(&nf_conntrack_lock);
+
+	helper = __nf_ct_helper_find(tuple);
+	if (helper) {
+		/* need to increase module usage count to assure helper will
+		 * not go away while the caller is e.g. busy putting a
+		 * conntrack in the hash that uses the helper */
+		if (!try_module_get(helper->me))
+			helper = NULL;
+	}
+
+	read_unlock_bh(&nf_conntrack_lock);
+
+	return helper;
+}
+
+void nf_ct_helper_put(struct nf_conntrack_helper *helper)
+{
+	module_put(helper->me);
+}
+
+struct nf_conntrack_helper *
+__nf_conntrack_helper_find_byname(const char *name)
+{
+	struct nf_conntrack_helper *h;
+
+	list_for_each_entry(h, &helpers, list) {
+		if (!strcmp(h->name, name))
+			return h;
+	}
+
+	return NULL;
+}
+
+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 && help->helper == me) {
+		nf_conntrack_event(IPCT_HELPER, ct);
+		help->helper = NULL;
+	}
+	return 0;
+}
+
+int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
+{
+	int ret;
+	BUG_ON(me->timeout == 0);
+
+	ret = nf_conntrack_register_cache(NF_CT_F_HELP, "nf_conntrack:help",
+					  sizeof(struct nf_conn)
+					  + sizeof(struct nf_conn_help)
+					  + __alignof__(struct nf_conn_help));
+	if (ret < 0) {
+		printk(KERN_ERR "nf_conntrack_helper_register: Unable to create slab cache for conntracks\n");
+		return ret;
+	}
+	write_lock_bh(&nf_conntrack_lock);
+	list_add(&me->list, &helpers);
+	write_unlock_bh(&nf_conntrack_lock);
+
+	return 0;
+}
+
+void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
+{
+	unsigned int i;
+	struct nf_conntrack_tuple_hash *h;
+	struct nf_conntrack_expect *exp, *tmp;
+
+	/* Need write lock here, to delete helper. */
+	write_lock_bh(&nf_conntrack_lock);
+	list_del(&me->list);
+
+	/* Get rid of expectations */
+	list_for_each_entry_safe(exp, tmp, &nf_conntrack_expect_list, list) {
+		struct nf_conn_help *help = nfct_help(exp->master);
+		if (help->helper == me && del_timer(&exp->timeout)) {
+			nf_ct_unlink_expect(exp);
+			nf_conntrack_expect_put(exp);
+		}
+	}
+
+	/* Get rid of expecteds, set helpers to NULL. */
+	list_for_each_entry(h, &unconfirmed, list)
+		unhelp(h, me);
+	for (i = 0; i < nf_conntrack_htable_size; i++) {
+		list_for_each_entry(h, &nf_conntrack_hash[i], list)
+			unhelp(h, me);
+	}
+	write_unlock_bh(&nf_conntrack_lock);
+
+	/* Someone could be still looking at the helper in a bh. */
+	synchronize_net();
+}