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 struct hlist_head
*nf_ct_helper_hash __read_mostly
;
34 EXPORT_SYMBOL_GPL(nf_ct_helper_hash
);
35 unsigned int nf_ct_helper_hsize __read_mostly
;
36 EXPORT_SYMBOL_GPL(nf_ct_helper_hsize
);
37 static unsigned int nf_ct_helper_count __read_mostly
;
39 static bool nf_ct_auto_assign_helper __read_mostly
= true;
40 module_param_named(nf_conntrack_helper
, nf_ct_auto_assign_helper
, bool, 0644);
41 MODULE_PARM_DESC(nf_conntrack_helper
,
42 "Enable automatic conntrack helper assignment (default 1)");
45 static struct ctl_table helper_sysctl_table
[] = {
47 .procname
= "nf_conntrack_helper",
48 .data
= &init_net
.ct
.sysctl_auto_assign_helper
,
49 .maxlen
= sizeof(unsigned int),
51 .proc_handler
= proc_dointvec
,
56 static int nf_conntrack_helper_init_sysctl(struct net
*net
)
58 struct ctl_table
*table
;
60 table
= kmemdup(helper_sysctl_table
, sizeof(helper_sysctl_table
),
65 table
[0].data
= &net
->ct
.sysctl_auto_assign_helper
;
67 /* Don't export sysctls to unprivileged users */
68 if (net
->user_ns
!= &init_user_ns
)
69 table
[0].procname
= NULL
;
71 net
->ct
.helper_sysctl_header
=
72 register_net_sysctl(net
, "net/netfilter", table
);
74 if (!net
->ct
.helper_sysctl_header
) {
75 pr_err("nf_conntrack_helper: can't register to sysctl.\n");
86 static void nf_conntrack_helper_fini_sysctl(struct net
*net
)
88 struct ctl_table
*table
;
90 table
= net
->ct
.helper_sysctl_header
->ctl_table_arg
;
91 unregister_net_sysctl_table(net
->ct
.helper_sysctl_header
);
95 static int nf_conntrack_helper_init_sysctl(struct net
*net
)
100 static void nf_conntrack_helper_fini_sysctl(struct net
*net
)
103 #endif /* CONFIG_SYSCTL */
105 /* Stupid hash, but collision free for the default registrations of the
106 * helpers currently in the kernel. */
107 static unsigned int helper_hash(const struct nf_conntrack_tuple
*tuple
)
109 return (((tuple
->src
.l3num
<< 8) | tuple
->dst
.protonum
) ^
110 (__force __u16
)tuple
->src
.u
.all
) % nf_ct_helper_hsize
;
113 static struct nf_conntrack_helper
*
114 __nf_ct_helper_find(const struct nf_conntrack_tuple
*tuple
)
116 struct nf_conntrack_helper
*helper
;
117 struct nf_conntrack_tuple_mask mask
= { .src
.u
.all
= htons(0xFFFF) };
118 struct hlist_node
*n
;
121 if (!nf_ct_helper_count
)
124 h
= helper_hash(tuple
);
125 hlist_for_each_entry_rcu(helper
, n
, &nf_ct_helper_hash
[h
], hnode
) {
126 if (nf_ct_tuple_src_mask_cmp(tuple
, &helper
->tuple
, &mask
))
132 struct nf_conntrack_helper
*
133 __nf_conntrack_helper_find(const char *name
, u16 l3num
, u8 protonum
)
135 struct nf_conntrack_helper
*h
;
136 struct hlist_node
*n
;
139 for (i
= 0; i
< nf_ct_helper_hsize
; i
++) {
140 hlist_for_each_entry_rcu(h
, n
, &nf_ct_helper_hash
[i
], hnode
) {
141 if (!strcmp(h
->name
, name
) &&
142 h
->tuple
.src
.l3num
== l3num
&&
143 h
->tuple
.dst
.protonum
== protonum
)
149 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find
);
151 struct nf_conntrack_helper
*
152 nf_conntrack_helper_try_module_get(const char *name
, u16 l3num
, u8 protonum
)
154 struct nf_conntrack_helper
*h
;
156 h
= __nf_conntrack_helper_find(name
, l3num
, protonum
);
157 #ifdef CONFIG_MODULES
159 if (request_module("nfct-helper-%s", name
) == 0)
160 h
= __nf_conntrack_helper_find(name
, l3num
, protonum
);
163 if (h
!= NULL
&& !try_module_get(h
->me
))
168 EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get
);
170 struct nf_conn_help
*
171 nf_ct_helper_ext_add(struct nf_conn
*ct
,
172 struct nf_conntrack_helper
*helper
, gfp_t gfp
)
174 struct nf_conn_help
*help
;
176 help
= nf_ct_ext_add_length(ct
, NF_CT_EXT_HELPER
,
177 helper
->data_len
, gfp
);
179 INIT_HLIST_HEAD(&help
->expectations
);
181 pr_debug("failed to add helper extension area");
184 EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add
);
186 int __nf_ct_try_assign_helper(struct nf_conn
*ct
, struct nf_conn
*tmpl
,
189 struct nf_conntrack_helper
*helper
= NULL
;
190 struct nf_conn_help
*help
;
191 struct net
*net
= nf_ct_net(ct
);
194 /* We already got a helper explicitly attached. The function
195 * nf_conntrack_alter_reply - in case NAT is in use - asks for looking
196 * the helper up again. Since now the user is in full control of
197 * making consistent helper configurations, skip this automatic
198 * re-lookup, otherwise we'll lose the helper.
200 if (test_bit(IPS_HELPER_BIT
, &ct
->status
))
204 help
= nfct_help(tmpl
);
206 helper
= help
->helper
;
207 set_bit(IPS_HELPER_BIT
, &ct
->status
);
211 help
= nfct_help(ct
);
212 if (net
->ct
.sysctl_auto_assign_helper
&& helper
== NULL
) {
213 helper
= __nf_ct_helper_find(&ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
);
214 if (unlikely(!net
->ct
.auto_assign_helper_warned
&& helper
)) {
215 pr_info("nf_conntrack: automatic helper "
216 "assignment is deprecated and it will "
217 "be removed soon. Use the iptables CT target "
218 "to attach helpers instead.\n");
219 net
->ct
.auto_assign_helper_warned
= true;
223 if (helper
== NULL
) {
225 RCU_INIT_POINTER(help
->helper
, NULL
);
230 help
= nf_ct_helper_ext_add(ct
, helper
, flags
);
236 /* We only allow helper re-assignment of the same sort since
237 * we cannot reallocate the helper extension area.
239 if (help
->helper
!= helper
) {
240 RCU_INIT_POINTER(help
->helper
, NULL
);
245 rcu_assign_pointer(help
->helper
, helper
);
249 EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper
);
251 static inline int unhelp(struct nf_conntrack_tuple_hash
*i
,
252 const struct nf_conntrack_helper
*me
)
254 struct nf_conn
*ct
= nf_ct_tuplehash_to_ctrack(i
);
255 struct nf_conn_help
*help
= nfct_help(ct
);
257 if (help
&& rcu_dereference_protected(
259 lockdep_is_held(&nf_conntrack_lock
)
261 nf_conntrack_event(IPCT_HELPER
, ct
);
262 RCU_INIT_POINTER(help
->helper
, NULL
);
267 void nf_ct_helper_destroy(struct nf_conn
*ct
)
269 struct nf_conn_help
*help
= nfct_help(ct
);
270 struct nf_conntrack_helper
*helper
;
274 helper
= rcu_dereference(help
->helper
);
275 if (helper
&& helper
->destroy
)
281 static LIST_HEAD(nf_ct_helper_expectfn_list
);
283 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn
*n
)
285 spin_lock_bh(&nf_conntrack_lock
);
286 list_add_rcu(&n
->head
, &nf_ct_helper_expectfn_list
);
287 spin_unlock_bh(&nf_conntrack_lock
);
289 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register
);
291 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn
*n
)
293 spin_lock_bh(&nf_conntrack_lock
);
294 list_del_rcu(&n
->head
);
295 spin_unlock_bh(&nf_conntrack_lock
);
297 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister
);
299 struct nf_ct_helper_expectfn
*
300 nf_ct_helper_expectfn_find_by_name(const char *name
)
302 struct nf_ct_helper_expectfn
*cur
;
306 list_for_each_entry_rcu(cur
, &nf_ct_helper_expectfn_list
, head
) {
307 if (!strcmp(cur
->name
, name
)) {
313 return found
? cur
: NULL
;
315 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name
);
317 struct nf_ct_helper_expectfn
*
318 nf_ct_helper_expectfn_find_by_symbol(const void *symbol
)
320 struct nf_ct_helper_expectfn
*cur
;
324 list_for_each_entry_rcu(cur
, &nf_ct_helper_expectfn_list
, head
) {
325 if (cur
->expectfn
== symbol
) {
331 return found
? cur
: NULL
;
333 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol
);
335 int nf_conntrack_helper_register(struct nf_conntrack_helper
*me
)
338 struct nf_conntrack_helper
*cur
;
339 struct hlist_node
*n
;
340 unsigned int h
= helper_hash(&me
->tuple
);
342 BUG_ON(me
->expect_policy
== NULL
);
343 BUG_ON(me
->expect_class_max
>= NF_CT_MAX_EXPECT_CLASSES
);
344 BUG_ON(strlen(me
->name
) > NF_CT_HELPER_NAME_LEN
- 1);
346 mutex_lock(&nf_ct_helper_mutex
);
347 hlist_for_each_entry(cur
, n
, &nf_ct_helper_hash
[h
], hnode
) {
348 if (strncmp(cur
->name
, me
->name
, NF_CT_HELPER_NAME_LEN
) == 0 &&
349 cur
->tuple
.src
.l3num
== me
->tuple
.src
.l3num
&&
350 cur
->tuple
.dst
.protonum
== me
->tuple
.dst
.protonum
) {
355 hlist_add_head_rcu(&me
->hnode
, &nf_ct_helper_hash
[h
]);
356 nf_ct_helper_count
++;
358 mutex_unlock(&nf_ct_helper_mutex
);
361 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register
);
363 static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
,
366 struct nf_conntrack_tuple_hash
*h
;
367 struct nf_conntrack_expect
*exp
;
368 const struct hlist_node
*n
, *next
;
369 const struct hlist_nulls_node
*nn
;
372 /* Get rid of expectations */
373 for (i
= 0; i
< nf_ct_expect_hsize
; i
++) {
374 hlist_for_each_entry_safe(exp
, n
, next
,
375 &net
->ct
.expect_hash
[i
], hnode
) {
376 struct nf_conn_help
*help
= nfct_help(exp
->master
);
377 if ((rcu_dereference_protected(
379 lockdep_is_held(&nf_conntrack_lock
)
380 ) == me
|| exp
->helper
== me
) &&
381 del_timer(&exp
->timeout
)) {
382 nf_ct_unlink_expect(exp
);
383 nf_ct_expect_put(exp
);
388 /* Get rid of expecteds, set helpers to NULL. */
389 hlist_nulls_for_each_entry(h
, nn
, &net
->ct
.unconfirmed
, hnnode
)
391 for (i
= 0; i
< net
->ct
.htable_size
; i
++) {
392 hlist_nulls_for_each_entry(h
, nn
, &net
->ct
.hash
[i
], hnnode
)
397 void nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
)
401 mutex_lock(&nf_ct_helper_mutex
);
402 hlist_del_rcu(&me
->hnode
);
403 nf_ct_helper_count
--;
404 mutex_unlock(&nf_ct_helper_mutex
);
406 /* Make sure every nothing is still using the helper unless its a
407 * connection in the hash.
412 spin_lock_bh(&nf_conntrack_lock
);
414 __nf_conntrack_helper_unregister(me
, net
);
415 spin_unlock_bh(&nf_conntrack_lock
);
418 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister
);
420 static struct nf_ct_ext_type helper_extend __read_mostly
= {
421 .len
= sizeof(struct nf_conn_help
),
422 .align
= __alignof__(struct nf_conn_help
),
423 .id
= NF_CT_EXT_HELPER
,
426 int nf_conntrack_helper_init(struct net
*net
)
430 net
->ct
.auto_assign_helper_warned
= false;
431 net
->ct
.sysctl_auto_assign_helper
= nf_ct_auto_assign_helper
;
433 if (net_eq(net
, &init_net
)) {
434 nf_ct_helper_hsize
= 1; /* gets rounded up to use one page */
436 nf_ct_alloc_hashtable(&nf_ct_helper_hsize
, 0);
437 if (!nf_ct_helper_hash
)
440 err
= nf_ct_extend_register(&helper_extend
);
445 err
= nf_conntrack_helper_init_sysctl(net
);
452 if (net_eq(net
, &init_net
))
453 nf_ct_extend_unregister(&helper_extend
);
455 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_hsize
);
459 void nf_conntrack_helper_fini(struct net
*net
)
461 nf_conntrack_helper_fini_sysctl(net
);
462 if (net_eq(net
, &init_net
)) {
463 nf_ct_extend_unregister(&helper_extend
);
464 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_hsize
);