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- /* 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);
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