This commit was manufactured by cvs2svn to create branch 'vserver'.

[linux-2.6.git] / net / netfilter / nf_conntrack_helper.c

diff --git a/net/netfilter/nf_conntrack_helper.c b/net/netfilter/nf_conntrack_helper.c
new file mode 100644 (file)
index 0000000..0743be4
--- /dev/null
+++ b/net/netfilter/nf_conntrack_helper.c
@@ -0,0 +1,155 @@
+/* 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>
+
+#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>
+
+static __read_mostly 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;
+}
+EXPORT_SYMBOL_GPL(nf_ct_helper_find_get);
+
+void nf_ct_helper_put(struct nf_conntrack_helper *helper)
+{
+       module_put(helper->me);
+}
+EXPORT_SYMBOL_GPL(nf_ct_helper_put);
+
+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;
+}
+EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find_byname);
+
+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 size, ret;
+
+       BUG_ON(me->timeout == 0);
+
+       size = ALIGN(sizeof(struct nf_conn), __alignof__(struct nf_conn_help)) +
+              sizeof(struct nf_conn_help);
+       ret = nf_conntrack_register_cache(NF_CT_F_HELP, "nf_conntrack:help",
+                                         size);
+       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;
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
+
+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 || exp->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();
+}
+EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);