1 /* Helper handling for netfilter. */
3 /* (C) 1999-2001 Paul `Rusty' Russell
4 * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
5 * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2 as
9 * published by the Free Software Foundation.
12 #include <linux/types.h>
13 #include <linux/netfilter.h>
14 #include <linux/module.h>
15 #include <linux/skbuff.h>
16 #include <linux/vmalloc.h>
17 #include <linux/stddef.h>
18 #include <linux/random.h>
19 #include <linux/err.h>
20 #include <linux/kernel.h>
21 #include <linux/netdevice.h>
22 #include <linux/rculist.h>
23 #include <linux/rtnetlink.h>
25 #include <net/netfilter/nf_conntrack.h>
26 #include <net/netfilter/nf_conntrack_l3proto.h>
27 #include <net/netfilter/nf_conntrack_l4proto.h>
28 #include <net/netfilter/nf_conntrack_helper.h>
29 #include <net/netfilter/nf_conntrack_core.h>
30 #include <net/netfilter/nf_conntrack_extend.h>
32 static DEFINE_MUTEX(nf_ct_helper_mutex
);
33 static struct hlist_head
*nf_ct_helper_hash __read_mostly
;
34 static unsigned int nf_ct_helper_hsize __read_mostly
;
35 static unsigned int nf_ct_helper_count __read_mostly
;
37 static bool nf_ct_auto_assign_helper __read_mostly
= true;
38 module_param_named(nf_conntrack_helper
, nf_ct_auto_assign_helper
, bool, 0644);
39 MODULE_PARM_DESC(nf_conntrack_helper
,
40 "Enable automatic conntrack helper assignment (default 1)");
43 static struct ctl_table helper_sysctl_table
[] = {
45 .procname
= "nf_conntrack_helper",
46 .data
= &init_net
.ct
.sysctl_auto_assign_helper
,
47 .maxlen
= sizeof(unsigned int),
49 .proc_handler
= proc_dointvec
,
54 static int nf_conntrack_helper_init_sysctl(struct net
*net
)
56 struct ctl_table
*table
;
58 table
= kmemdup(helper_sysctl_table
, sizeof(helper_sysctl_table
),
63 table
[0].data
= &net
->ct
.sysctl_auto_assign_helper
;
65 net
->ct
.helper_sysctl_header
=
66 register_net_sysctl(net
, "net/netfilter", table
);
68 if (!net
->ct
.helper_sysctl_header
) {
69 pr_err("nf_conntrack_helper: can't register to sysctl.\n");
80 static void nf_conntrack_helper_fini_sysctl(struct net
*net
)
82 struct ctl_table
*table
;
84 table
= net
->ct
.helper_sysctl_header
->ctl_table_arg
;
85 unregister_net_sysctl_table(net
->ct
.helper_sysctl_header
);
89 static int nf_conntrack_helper_init_sysctl(struct net
*net
)
94 static void nf_conntrack_helper_fini_sysctl(struct net
*net
)
97 #endif /* CONFIG_SYSCTL */
99 /* Stupid hash, but collision free for the default registrations of the
100 * helpers currently in the kernel. */
101 static unsigned int helper_hash(const struct nf_conntrack_tuple
*tuple
)
103 return (((tuple
->src
.l3num
<< 8) | tuple
->dst
.protonum
) ^
104 (__force __u16
)tuple
->src
.u
.all
) % nf_ct_helper_hsize
;
107 static struct nf_conntrack_helper
*
108 __nf_ct_helper_find(const struct nf_conntrack_tuple
*tuple
)
110 struct nf_conntrack_helper
*helper
;
111 struct nf_conntrack_tuple_mask mask
= { .src
.u
.all
= htons(0xFFFF) };
112 struct hlist_node
*n
;
115 if (!nf_ct_helper_count
)
118 h
= helper_hash(tuple
);
119 hlist_for_each_entry_rcu(helper
, n
, &nf_ct_helper_hash
[h
], hnode
) {
120 if (nf_ct_tuple_src_mask_cmp(tuple
, &helper
->tuple
, &mask
))
126 struct nf_conntrack_helper
*
127 __nf_conntrack_helper_find(const char *name
, u16 l3num
, u8 protonum
)
129 struct nf_conntrack_helper
*h
;
130 struct hlist_node
*n
;
133 for (i
= 0; i
< nf_ct_helper_hsize
; i
++) {
134 hlist_for_each_entry_rcu(h
, n
, &nf_ct_helper_hash
[i
], hnode
) {
135 if (!strcmp(h
->name
, name
) &&
136 h
->tuple
.src
.l3num
== l3num
&&
137 h
->tuple
.dst
.protonum
== protonum
)
143 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find
);
145 struct nf_conntrack_helper
*
146 nf_conntrack_helper_try_module_get(const char *name
, u16 l3num
, u8 protonum
)
148 struct nf_conntrack_helper
*h
;
150 h
= __nf_conntrack_helper_find(name
, l3num
, protonum
);
151 #ifdef CONFIG_MODULES
153 if (request_module("nfct-helper-%s", name
) == 0)
154 h
= __nf_conntrack_helper_find(name
, l3num
, protonum
);
157 if (h
!= NULL
&& !try_module_get(h
->me
))
162 EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get
);
164 struct nf_conn_help
*nf_ct_helper_ext_add(struct nf_conn
*ct
, gfp_t gfp
)
166 struct nf_conn_help
*help
;
168 help
= nf_ct_ext_add(ct
, NF_CT_EXT_HELPER
, gfp
);
170 INIT_HLIST_HEAD(&help
->expectations
);
172 pr_debug("failed to add helper extension area");
175 EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add
);
177 int __nf_ct_try_assign_helper(struct nf_conn
*ct
, struct nf_conn
*tmpl
,
180 struct nf_conntrack_helper
*helper
= NULL
;
181 struct nf_conn_help
*help
;
182 struct net
*net
= nf_ct_net(ct
);
185 /* We already got a helper explicitly attached. The function
186 * nf_conntrack_alter_reply - in case NAT is in use - asks for looking
187 * the helper up again. Since now the user is in full control of
188 * making consistent helper configurations, skip this automatic
189 * re-lookup, otherwise we'll lose the helper.
191 if (test_bit(IPS_HELPER_BIT
, &ct
->status
))
195 help
= nfct_help(tmpl
);
197 helper
= help
->helper
;
198 set_bit(IPS_HELPER_BIT
, &ct
->status
);
202 help
= nfct_help(ct
);
203 if (net
->ct
.sysctl_auto_assign_helper
&& helper
== NULL
) {
204 helper
= __nf_ct_helper_find(&ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
);
205 if (unlikely(!net
->ct
.auto_assign_helper_warned
&& helper
)) {
206 pr_info("nf_conntrack: automatic helper "
207 "assignment is deprecated and it will "
208 "be removed soon. Use the iptables CT target "
209 "to attach helpers instead.\n");
210 net
->ct
.auto_assign_helper_warned
= true;
214 if (helper
== NULL
) {
216 RCU_INIT_POINTER(help
->helper
, NULL
);
221 help
= nf_ct_helper_ext_add(ct
, flags
);
227 memset(&help
->help
, 0, sizeof(help
->help
));
230 rcu_assign_pointer(help
->helper
, helper
);
234 EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper
);
236 static inline int unhelp(struct nf_conntrack_tuple_hash
*i
,
237 const struct nf_conntrack_helper
*me
)
239 struct nf_conn
*ct
= nf_ct_tuplehash_to_ctrack(i
);
240 struct nf_conn_help
*help
= nfct_help(ct
);
242 if (help
&& rcu_dereference_protected(
244 lockdep_is_held(&nf_conntrack_lock
)
246 nf_conntrack_event(IPCT_HELPER
, ct
);
247 RCU_INIT_POINTER(help
->helper
, NULL
);
252 void nf_ct_helper_destroy(struct nf_conn
*ct
)
254 struct nf_conn_help
*help
= nfct_help(ct
);
255 struct nf_conntrack_helper
*helper
;
259 helper
= rcu_dereference(help
->helper
);
260 if (helper
&& helper
->destroy
)
266 static LIST_HEAD(nf_ct_helper_expectfn_list
);
268 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn
*n
)
270 spin_lock_bh(&nf_conntrack_lock
);
271 list_add_rcu(&n
->head
, &nf_ct_helper_expectfn_list
);
272 spin_unlock_bh(&nf_conntrack_lock
);
274 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register
);
276 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn
*n
)
278 spin_lock_bh(&nf_conntrack_lock
);
279 list_del_rcu(&n
->head
);
280 spin_unlock_bh(&nf_conntrack_lock
);
282 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister
);
284 struct nf_ct_helper_expectfn
*
285 nf_ct_helper_expectfn_find_by_name(const char *name
)
287 struct nf_ct_helper_expectfn
*cur
;
291 list_for_each_entry_rcu(cur
, &nf_ct_helper_expectfn_list
, head
) {
292 if (!strcmp(cur
->name
, name
)) {
298 return found
? cur
: NULL
;
300 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name
);
302 struct nf_ct_helper_expectfn
*
303 nf_ct_helper_expectfn_find_by_symbol(const void *symbol
)
305 struct nf_ct_helper_expectfn
*cur
;
309 list_for_each_entry_rcu(cur
, &nf_ct_helper_expectfn_list
, head
) {
310 if (cur
->expectfn
== symbol
) {
316 return found
? cur
: NULL
;
318 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol
);
320 int nf_conntrack_helper_register(struct nf_conntrack_helper
*me
)
322 unsigned int h
= helper_hash(&me
->tuple
);
324 BUG_ON(me
->expect_policy
== NULL
);
325 BUG_ON(me
->expect_class_max
>= NF_CT_MAX_EXPECT_CLASSES
);
326 BUG_ON(strlen(me
->name
) > NF_CT_HELPER_NAME_LEN
- 1);
328 mutex_lock(&nf_ct_helper_mutex
);
329 hlist_add_head_rcu(&me
->hnode
, &nf_ct_helper_hash
[h
]);
330 nf_ct_helper_count
++;
331 mutex_unlock(&nf_ct_helper_mutex
);
335 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register
);
337 static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
,
340 struct nf_conntrack_tuple_hash
*h
;
341 struct nf_conntrack_expect
*exp
;
342 const struct hlist_node
*n
, *next
;
343 const struct hlist_nulls_node
*nn
;
346 /* Get rid of expectations */
347 for (i
= 0; i
< nf_ct_expect_hsize
; i
++) {
348 hlist_for_each_entry_safe(exp
, n
, next
,
349 &net
->ct
.expect_hash
[i
], hnode
) {
350 struct nf_conn_help
*help
= nfct_help(exp
->master
);
351 if ((rcu_dereference_protected(
353 lockdep_is_held(&nf_conntrack_lock
)
354 ) == me
|| exp
->helper
== me
) &&
355 del_timer(&exp
->timeout
)) {
356 nf_ct_unlink_expect(exp
);
357 nf_ct_expect_put(exp
);
362 /* Get rid of expecteds, set helpers to NULL. */
363 hlist_nulls_for_each_entry(h
, nn
, &net
->ct
.unconfirmed
, hnnode
)
365 for (i
= 0; i
< net
->ct
.htable_size
; i
++) {
366 hlist_nulls_for_each_entry(h
, nn
, &net
->ct
.hash
[i
], hnnode
)
371 void nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
)
375 mutex_lock(&nf_ct_helper_mutex
);
376 hlist_del_rcu(&me
->hnode
);
377 nf_ct_helper_count
--;
378 mutex_unlock(&nf_ct_helper_mutex
);
380 /* Make sure every nothing is still using the helper unless its a
381 * connection in the hash.
386 spin_lock_bh(&nf_conntrack_lock
);
388 __nf_conntrack_helper_unregister(me
, net
);
389 spin_unlock_bh(&nf_conntrack_lock
);
392 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister
);
394 static struct nf_ct_ext_type helper_extend __read_mostly
= {
395 .len
= sizeof(struct nf_conn_help
),
396 .align
= __alignof__(struct nf_conn_help
),
397 .id
= NF_CT_EXT_HELPER
,
400 int nf_conntrack_helper_init(struct net
*net
)
404 net
->ct
.auto_assign_helper_warned
= false;
405 net
->ct
.sysctl_auto_assign_helper
= nf_ct_auto_assign_helper
;
407 if (net_eq(net
, &init_net
)) {
408 nf_ct_helper_hsize
= 1; /* gets rounded up to use one page */
410 nf_ct_alloc_hashtable(&nf_ct_helper_hsize
, 0);
411 if (!nf_ct_helper_hash
)
414 err
= nf_ct_extend_register(&helper_extend
);
419 err
= nf_conntrack_helper_init_sysctl(net
);
426 if (net_eq(net
, &init_net
))
427 nf_ct_extend_unregister(&helper_extend
);
429 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_hsize
);
433 void nf_conntrack_helper_fini(struct net
*net
)
435 nf_conntrack_helper_fini_sysctl(net
);
436 if (net_eq(net
, &init_net
)) {
437 nf_ct_extend_unregister(&helper_extend
);
438 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_hsize
);