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>
6 * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
8 * This program is free software; you can redistribute it and/or modify
9 * it under the terms of the GNU General Public License version 2 as
10 * published by the Free Software Foundation.
13 #include <linux/types.h>
14 #include <linux/netfilter.h>
15 #include <linux/module.h>
16 #include <linux/skbuff.h>
17 #include <linux/vmalloc.h>
18 #include <linux/stddef.h>
19 #include <linux/random.h>
20 #include <linux/err.h>
21 #include <linux/kernel.h>
22 #include <linux/netdevice.h>
23 #include <linux/rculist.h>
24 #include <linux/rtnetlink.h>
26 #include <net/netfilter/nf_conntrack.h>
27 #include <net/netfilter/nf_conntrack_l3proto.h>
28 #include <net/netfilter/nf_conntrack_l4proto.h>
29 #include <net/netfilter/nf_conntrack_helper.h>
30 #include <net/netfilter/nf_conntrack_core.h>
31 #include <net/netfilter/nf_conntrack_extend.h>
32 #include <net/netfilter/nf_log.h>
34 static DEFINE_MUTEX(nf_ct_helper_mutex
);
35 struct hlist_head
*nf_ct_helper_hash __read_mostly
;
36 EXPORT_SYMBOL_GPL(nf_ct_helper_hash
);
37 unsigned int nf_ct_helper_hsize __read_mostly
;
38 EXPORT_SYMBOL_GPL(nf_ct_helper_hsize
);
39 static unsigned int nf_ct_helper_count __read_mostly
;
41 static bool nf_ct_auto_assign_helper __read_mostly
= false;
42 module_param_named(nf_conntrack_helper
, nf_ct_auto_assign_helper
, bool, 0644);
43 MODULE_PARM_DESC(nf_conntrack_helper
,
44 "Enable automatic conntrack helper assignment (default 0)");
47 static struct ctl_table helper_sysctl_table
[] = {
49 .procname
= "nf_conntrack_helper",
50 .data
= &init_net
.ct
.sysctl_auto_assign_helper
,
51 .maxlen
= sizeof(unsigned int),
53 .proc_handler
= proc_dointvec
,
58 static int nf_conntrack_helper_init_sysctl(struct net
*net
)
60 struct ctl_table
*table
;
62 table
= kmemdup(helper_sysctl_table
, sizeof(helper_sysctl_table
),
67 table
[0].data
= &net
->ct
.sysctl_auto_assign_helper
;
69 /* Don't export sysctls to unprivileged users */
70 if (net
->user_ns
!= &init_user_ns
)
71 table
[0].procname
= NULL
;
73 net
->ct
.helper_sysctl_header
=
74 register_net_sysctl(net
, "net/netfilter", table
);
76 if (!net
->ct
.helper_sysctl_header
) {
77 pr_err("nf_conntrack_helper: can't register to sysctl.\n");
88 static void nf_conntrack_helper_fini_sysctl(struct net
*net
)
90 struct ctl_table
*table
;
92 table
= net
->ct
.helper_sysctl_header
->ctl_table_arg
;
93 unregister_net_sysctl_table(net
->ct
.helper_sysctl_header
);
97 static int nf_conntrack_helper_init_sysctl(struct net
*net
)
102 static void nf_conntrack_helper_fini_sysctl(struct net
*net
)
105 #endif /* CONFIG_SYSCTL */
107 /* Stupid hash, but collision free for the default registrations of the
108 * helpers currently in the kernel. */
109 static unsigned int helper_hash(const struct nf_conntrack_tuple
*tuple
)
111 return (((tuple
->src
.l3num
<< 8) | tuple
->dst
.protonum
) ^
112 (__force __u16
)tuple
->src
.u
.all
) % nf_ct_helper_hsize
;
115 static struct nf_conntrack_helper
*
116 __nf_ct_helper_find(const struct nf_conntrack_tuple
*tuple
)
118 struct nf_conntrack_helper
*helper
;
119 struct nf_conntrack_tuple_mask mask
= { .src
.u
.all
= htons(0xFFFF) };
122 if (!nf_ct_helper_count
)
125 h
= helper_hash(tuple
);
126 hlist_for_each_entry_rcu(helper
, &nf_ct_helper_hash
[h
], hnode
) {
127 if (nf_ct_tuple_src_mask_cmp(tuple
, &helper
->tuple
, &mask
))
133 struct nf_conntrack_helper
*
134 __nf_conntrack_helper_find(const char *name
, u16 l3num
, u8 protonum
)
136 struct nf_conntrack_helper
*h
;
139 for (i
= 0; i
< nf_ct_helper_hsize
; i
++) {
140 hlist_for_each_entry_rcu(h
, &nf_ct_helper_hash
[i
], hnode
) {
141 if (strcmp(h
->name
, name
))
144 if (h
->tuple
.src
.l3num
!= NFPROTO_UNSPEC
&&
145 h
->tuple
.src
.l3num
!= l3num
)
148 if (h
->tuple
.dst
.protonum
== protonum
)
154 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find
);
156 struct nf_conntrack_helper
*
157 nf_conntrack_helper_try_module_get(const char *name
, u16 l3num
, u8 protonum
)
159 struct nf_conntrack_helper
*h
;
161 h
= __nf_conntrack_helper_find(name
, l3num
, protonum
);
162 #ifdef CONFIG_MODULES
164 if (request_module("nfct-helper-%s", name
) == 0)
165 h
= __nf_conntrack_helper_find(name
, l3num
, protonum
);
168 if (h
!= NULL
&& !try_module_get(h
->me
))
173 EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get
);
175 struct nf_conn_help
*
176 nf_ct_helper_ext_add(struct nf_conn
*ct
,
177 struct nf_conntrack_helper
*helper
, gfp_t gfp
)
179 struct nf_conn_help
*help
;
181 help
= nf_ct_ext_add_length(ct
, NF_CT_EXT_HELPER
,
182 helper
->data_len
, gfp
);
184 INIT_HLIST_HEAD(&help
->expectations
);
186 pr_debug("failed to add helper extension area");
189 EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add
);
191 static struct nf_conntrack_helper
*
192 nf_ct_lookup_helper(struct nf_conn
*ct
, struct net
*net
)
194 if (!net
->ct
.sysctl_auto_assign_helper
) {
195 if (net
->ct
.auto_assign_helper_warned
)
197 if (!__nf_ct_helper_find(&ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
))
199 pr_info("nf_conntrack: default automatic helper assignment "
200 "has been turned off for security reasons and CT-based "
201 " firewall rule not found. Use the iptables CT target "
202 "to attach helpers instead.\n");
203 net
->ct
.auto_assign_helper_warned
= 1;
207 return __nf_ct_helper_find(&ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
);
211 int __nf_ct_try_assign_helper(struct nf_conn
*ct
, struct nf_conn
*tmpl
,
214 struct nf_conntrack_helper
*helper
= NULL
;
215 struct nf_conn_help
*help
;
216 struct net
*net
= nf_ct_net(ct
);
218 /* We already got a helper explicitly attached. The function
219 * nf_conntrack_alter_reply - in case NAT is in use - asks for looking
220 * the helper up again. Since now the user is in full control of
221 * making consistent helper configurations, skip this automatic
222 * re-lookup, otherwise we'll lose the helper.
224 if (test_bit(IPS_HELPER_BIT
, &ct
->status
))
228 help
= nfct_help(tmpl
);
230 helper
= help
->helper
;
231 set_bit(IPS_HELPER_BIT
, &ct
->status
);
235 help
= nfct_help(ct
);
237 if (helper
== NULL
) {
238 helper
= nf_ct_lookup_helper(ct
, net
);
239 if (helper
== NULL
) {
241 RCU_INIT_POINTER(help
->helper
, NULL
);
247 help
= nf_ct_helper_ext_add(ct
, helper
, flags
);
251 /* We only allow helper re-assignment of the same sort since
252 * we cannot reallocate the helper extension area.
254 struct nf_conntrack_helper
*tmp
= rcu_dereference(help
->helper
);
256 if (tmp
&& tmp
->help
!= helper
->help
) {
257 RCU_INIT_POINTER(help
->helper
, NULL
);
262 rcu_assign_pointer(help
->helper
, helper
);
266 EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper
);
268 /* appropriate ct lock protecting must be taken by caller */
269 static inline int unhelp(struct nf_conntrack_tuple_hash
*i
,
270 const struct nf_conntrack_helper
*me
)
272 struct nf_conn
*ct
= nf_ct_tuplehash_to_ctrack(i
);
273 struct nf_conn_help
*help
= nfct_help(ct
);
275 if (help
&& rcu_dereference_raw(help
->helper
) == me
) {
276 nf_conntrack_event(IPCT_HELPER
, ct
);
277 RCU_INIT_POINTER(help
->helper
, NULL
);
282 void nf_ct_helper_destroy(struct nf_conn
*ct
)
284 struct nf_conn_help
*help
= nfct_help(ct
);
285 struct nf_conntrack_helper
*helper
;
289 helper
= rcu_dereference(help
->helper
);
290 if (helper
&& helper
->destroy
)
296 static LIST_HEAD(nf_ct_helper_expectfn_list
);
298 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn
*n
)
300 spin_lock_bh(&nf_conntrack_expect_lock
);
301 list_add_rcu(&n
->head
, &nf_ct_helper_expectfn_list
);
302 spin_unlock_bh(&nf_conntrack_expect_lock
);
304 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register
);
306 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn
*n
)
308 spin_lock_bh(&nf_conntrack_expect_lock
);
309 list_del_rcu(&n
->head
);
310 spin_unlock_bh(&nf_conntrack_expect_lock
);
312 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister
);
314 struct nf_ct_helper_expectfn
*
315 nf_ct_helper_expectfn_find_by_name(const char *name
)
317 struct nf_ct_helper_expectfn
*cur
;
321 list_for_each_entry_rcu(cur
, &nf_ct_helper_expectfn_list
, head
) {
322 if (!strcmp(cur
->name
, name
)) {
328 return found
? cur
: NULL
;
330 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name
);
332 struct nf_ct_helper_expectfn
*
333 nf_ct_helper_expectfn_find_by_symbol(const void *symbol
)
335 struct nf_ct_helper_expectfn
*cur
;
339 list_for_each_entry_rcu(cur
, &nf_ct_helper_expectfn_list
, head
) {
340 if (cur
->expectfn
== symbol
) {
346 return found
? cur
: NULL
;
348 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol
);
351 void nf_ct_helper_log(struct sk_buff
*skb
, const struct nf_conn
*ct
,
352 const char *fmt
, ...)
354 const struct nf_conn_help
*help
;
355 const struct nf_conntrack_helper
*helper
;
356 struct va_format vaf
;
364 /* Called from the helper function, this call never fails */
365 help
= nfct_help(ct
);
367 /* rcu_read_lock()ed by nf_hook_thresh */
368 helper
= rcu_dereference(help
->helper
);
370 nf_log_packet(nf_ct_net(ct
), nf_ct_l3num(ct
), 0, skb
, NULL
, NULL
, NULL
,
371 "nf_ct_%s: dropping packet: %pV ", helper
->name
, &vaf
);
375 EXPORT_SYMBOL_GPL(nf_ct_helper_log
);
377 int nf_conntrack_helper_register(struct nf_conntrack_helper
*me
)
379 struct nf_conntrack_tuple_mask mask
= { .src
.u
.all
= htons(0xFFFF) };
380 unsigned int h
= helper_hash(&me
->tuple
);
381 struct nf_conntrack_helper
*cur
;
384 BUG_ON(me
->expect_policy
== NULL
);
385 BUG_ON(me
->expect_class_max
>= NF_CT_MAX_EXPECT_CLASSES
);
386 BUG_ON(strlen(me
->name
) > NF_CT_HELPER_NAME_LEN
- 1);
388 mutex_lock(&nf_ct_helper_mutex
);
389 hlist_for_each_entry(cur
, &nf_ct_helper_hash
[h
], hnode
) {
390 if (nf_ct_tuple_src_mask_cmp(&cur
->tuple
, &me
->tuple
, &mask
)) {
395 hlist_add_head_rcu(&me
->hnode
, &nf_ct_helper_hash
[h
]);
396 nf_ct_helper_count
++;
398 mutex_unlock(&nf_ct_helper_mutex
);
401 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register
);
403 static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
,
406 struct nf_conntrack_tuple_hash
*h
;
407 const struct hlist_nulls_node
*nn
;
410 /* Get rid of expecteds, set helpers to NULL. */
411 for_each_possible_cpu(cpu
) {
412 struct ct_pcpu
*pcpu
= per_cpu_ptr(net
->ct
.pcpu_lists
, cpu
);
414 spin_lock_bh(&pcpu
->lock
);
415 hlist_nulls_for_each_entry(h
, nn
, &pcpu
->unconfirmed
, hnnode
)
417 spin_unlock_bh(&pcpu
->lock
);
421 void nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
)
423 struct nf_conntrack_tuple_hash
*h
;
424 struct nf_conntrack_expect
*exp
;
425 const struct hlist_node
*next
;
426 const struct hlist_nulls_node
*nn
;
427 unsigned int last_hsize
;
432 mutex_lock(&nf_ct_helper_mutex
);
433 hlist_del_rcu(&me
->hnode
);
434 nf_ct_helper_count
--;
435 mutex_unlock(&nf_ct_helper_mutex
);
437 /* Make sure every nothing is still using the helper unless its a
438 * connection in the hash.
442 /* Get rid of expectations */
443 spin_lock_bh(&nf_conntrack_expect_lock
);
444 for (i
= 0; i
< nf_ct_expect_hsize
; i
++) {
445 hlist_for_each_entry_safe(exp
, next
,
446 &nf_ct_expect_hash
[i
], hnode
) {
447 struct nf_conn_help
*help
= nfct_help(exp
->master
);
448 if ((rcu_dereference_protected(
450 lockdep_is_held(&nf_conntrack_expect_lock
)
451 ) == me
|| exp
->helper
== me
) &&
452 del_timer(&exp
->timeout
)) {
453 nf_ct_unlink_expect(exp
);
454 nf_ct_expect_put(exp
);
458 spin_unlock_bh(&nf_conntrack_expect_lock
);
462 __nf_conntrack_helper_unregister(me
, net
);
467 last_hsize
= nf_conntrack_htable_size
;
468 for (i
= 0; i
< last_hsize
; i
++) {
469 lock
= &nf_conntrack_locks
[i
% CONNTRACK_LOCKS
];
470 nf_conntrack_lock(lock
);
471 if (last_hsize
!= nf_conntrack_htable_size
) {
475 hlist_nulls_for_each_entry(h
, nn
, &nf_conntrack_hash
[i
], hnnode
)
481 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister
);
483 void nf_ct_helper_init(struct nf_conntrack_helper
*helper
,
484 u16 l3num
, u16 protonum
, const char *name
,
485 u16 default_port
, u16 spec_port
, u32 id
,
486 const struct nf_conntrack_expect_policy
*exp_pol
,
487 u32 expect_class_max
, u32 data_len
,
488 int (*help
)(struct sk_buff
*skb
, unsigned int protoff
,
490 enum ip_conntrack_info ctinfo
),
491 int (*from_nlattr
)(struct nlattr
*attr
,
493 struct module
*module
)
495 helper
->tuple
.src
.l3num
= l3num
;
496 helper
->tuple
.dst
.protonum
= protonum
;
497 helper
->tuple
.src
.u
.all
= htons(spec_port
);
498 helper
->expect_policy
= exp_pol
;
499 helper
->expect_class_max
= expect_class_max
;
500 helper
->data_len
= data_len
;
502 helper
->from_nlattr
= from_nlattr
;
505 if (spec_port
== default_port
)
506 snprintf(helper
->name
, sizeof(helper
->name
), "%s", name
);
508 snprintf(helper
->name
, sizeof(helper
->name
), "%s-%u", name
, id
);
510 EXPORT_SYMBOL_GPL(nf_ct_helper_init
);
512 int nf_conntrack_helpers_register(struct nf_conntrack_helper
*helper
,
518 for (i
= 0; i
< n
; i
++) {
519 err
= nf_conntrack_helper_register(&helper
[i
]);
527 nf_conntrack_helpers_unregister(helper
, i
);
530 EXPORT_SYMBOL_GPL(nf_conntrack_helpers_register
);
532 void nf_conntrack_helpers_unregister(struct nf_conntrack_helper
*helper
,
536 nf_conntrack_helper_unregister(&helper
[n
]);
538 EXPORT_SYMBOL_GPL(nf_conntrack_helpers_unregister
);
540 static struct nf_ct_ext_type helper_extend __read_mostly
= {
541 .len
= sizeof(struct nf_conn_help
),
542 .align
= __alignof__(struct nf_conn_help
),
543 .id
= NF_CT_EXT_HELPER
,
546 int nf_conntrack_helper_pernet_init(struct net
*net
)
548 net
->ct
.auto_assign_helper_warned
= false;
549 net
->ct
.sysctl_auto_assign_helper
= nf_ct_auto_assign_helper
;
550 return nf_conntrack_helper_init_sysctl(net
);
553 void nf_conntrack_helper_pernet_fini(struct net
*net
)
555 nf_conntrack_helper_fini_sysctl(net
);
558 int nf_conntrack_helper_init(void)
561 nf_ct_helper_hsize
= 1; /* gets rounded up to use one page */
563 nf_ct_alloc_hashtable(&nf_ct_helper_hsize
, 0);
564 if (!nf_ct_helper_hash
)
567 ret
= nf_ct_extend_register(&helper_extend
);
569 pr_err("nf_ct_helper: Unable to register helper extension.\n");
575 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_hsize
);
579 void nf_conntrack_helper_fini(void)
581 nf_ct_extend_unregister(&helper_extend
);
582 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_hsize
);