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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>
#include <net/netfilter/nf_conntrack_extend.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;
struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
list_for_each_entry(h, &helpers, list) {
if (nf_ct_tuple_src_mask_cmp(tuple, &h->tuple, &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);
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);
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);
rcu_assign_pointer(help->helper, NULL);
}
return 0;
}
int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
{
BUG_ON(me->timeout == 0);
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)
{
struct nf_conntrack_tuple_hash *h;
struct nf_conntrack_expect *exp;
struct hlist_node *n, *next;
unsigned int i;
/* Need write lock here, to delete helper. */
write_lock_bh(&nf_conntrack_lock);
list_del(&me->list);
/* Get rid of expectations */
for (i = 0; i < nf_ct_expect_hsize; i++) {
hlist_for_each_entry_safe(exp, n, next,
&nf_ct_expect_hash[i], hnode) {
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_ct_expect_put(exp);
}
}
}
/* Get rid of expecteds, set helpers to NULL. */
hlist_for_each_entry(h, n, &unconfirmed, hnode)
unhelp(h, me);
for (i = 0; i < nf_conntrack_htable_size; i++) {
hlist_for_each_entry(h, n, &nf_conntrack_hash[i], hnode)
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);
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()
{
return nf_ct_extend_register(&helper_extend);
}
void nf_conntrack_helper_fini()
{
nf_ct_extend_unregister(&helper_extend);
}
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