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
= true;
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 1)");
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
) &&
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 struct nf_conntrack_helper
*tmp
= rcu_dereference(help
->helper
);
241 if (tmp
&& tmp
->help
!= helper
->help
) {
242 RCU_INIT_POINTER(help
->helper
, NULL
);
247 rcu_assign_pointer(help
->helper
, helper
);
251 EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper
);
253 static inline int unhelp(struct nf_conntrack_tuple_hash
*i
,
254 const struct nf_conntrack_helper
*me
)
256 struct nf_conn
*ct
= nf_ct_tuplehash_to_ctrack(i
);
257 struct nf_conn_help
*help
= nfct_help(ct
);
259 if (help
&& rcu_dereference_protected(
261 lockdep_is_held(&nf_conntrack_lock
)
263 nf_conntrack_event(IPCT_HELPER
, ct
);
264 RCU_INIT_POINTER(help
->helper
, NULL
);
269 void nf_ct_helper_destroy(struct nf_conn
*ct
)
271 struct nf_conn_help
*help
= nfct_help(ct
);
272 struct nf_conntrack_helper
*helper
;
276 helper
= rcu_dereference(help
->helper
);
277 if (helper
&& helper
->destroy
)
283 static LIST_HEAD(nf_ct_helper_expectfn_list
);
285 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn
*n
)
287 spin_lock_bh(&nf_conntrack_lock
);
288 list_add_rcu(&n
->head
, &nf_ct_helper_expectfn_list
);
289 spin_unlock_bh(&nf_conntrack_lock
);
291 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register
);
293 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn
*n
)
295 spin_lock_bh(&nf_conntrack_lock
);
296 list_del_rcu(&n
->head
);
297 spin_unlock_bh(&nf_conntrack_lock
);
299 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister
);
301 struct nf_ct_helper_expectfn
*
302 nf_ct_helper_expectfn_find_by_name(const char *name
)
304 struct nf_ct_helper_expectfn
*cur
;
308 list_for_each_entry_rcu(cur
, &nf_ct_helper_expectfn_list
, head
) {
309 if (!strcmp(cur
->name
, name
)) {
315 return found
? cur
: NULL
;
317 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name
);
319 struct nf_ct_helper_expectfn
*
320 nf_ct_helper_expectfn_find_by_symbol(const void *symbol
)
322 struct nf_ct_helper_expectfn
*cur
;
326 list_for_each_entry_rcu(cur
, &nf_ct_helper_expectfn_list
, head
) {
327 if (cur
->expectfn
== symbol
) {
333 return found
? cur
: NULL
;
335 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol
);
338 void nf_ct_helper_log(struct sk_buff
*skb
, const struct nf_conn
*ct
,
339 const char *fmt
, ...)
341 const struct nf_conn_help
*help
;
342 const struct nf_conntrack_helper
*helper
;
343 struct va_format vaf
;
351 /* Called from the helper function, this call never fails */
352 help
= nfct_help(ct
);
354 /* rcu_read_lock()ed by nf_hook_slow */
355 helper
= rcu_dereference(help
->helper
);
357 nf_log_packet(nf_ct_net(ct
), nf_ct_l3num(ct
), 0, skb
, NULL
, NULL
, NULL
,
358 "nf_ct_%s: dropping packet: %pV ", helper
->name
, &vaf
);
362 EXPORT_SYMBOL_GPL(nf_ct_helper_log
);
364 int nf_conntrack_helper_register(struct nf_conntrack_helper
*me
)
367 struct nf_conntrack_helper
*cur
;
368 unsigned int h
= helper_hash(&me
->tuple
);
370 BUG_ON(me
->expect_policy
== NULL
);
371 BUG_ON(me
->expect_class_max
>= NF_CT_MAX_EXPECT_CLASSES
);
372 BUG_ON(strlen(me
->name
) > NF_CT_HELPER_NAME_LEN
- 1);
374 mutex_lock(&nf_ct_helper_mutex
);
375 hlist_for_each_entry(cur
, &nf_ct_helper_hash
[h
], hnode
) {
376 if (strncmp(cur
->name
, me
->name
, NF_CT_HELPER_NAME_LEN
) == 0 &&
377 cur
->tuple
.src
.l3num
== me
->tuple
.src
.l3num
&&
378 cur
->tuple
.dst
.protonum
== me
->tuple
.dst
.protonum
) {
383 hlist_add_head_rcu(&me
->hnode
, &nf_ct_helper_hash
[h
]);
384 nf_ct_helper_count
++;
386 mutex_unlock(&nf_ct_helper_mutex
);
389 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register
);
391 static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
,
394 struct nf_conntrack_tuple_hash
*h
;
395 struct nf_conntrack_expect
*exp
;
396 const struct hlist_node
*next
;
397 const struct hlist_nulls_node
*nn
;
400 /* Get rid of expectations */
401 for (i
= 0; i
< nf_ct_expect_hsize
; i
++) {
402 hlist_for_each_entry_safe(exp
, next
,
403 &net
->ct
.expect_hash
[i
], hnode
) {
404 struct nf_conn_help
*help
= nfct_help(exp
->master
);
405 if ((rcu_dereference_protected(
407 lockdep_is_held(&nf_conntrack_lock
)
408 ) == me
|| exp
->helper
== me
) &&
409 del_timer(&exp
->timeout
)) {
410 nf_ct_unlink_expect(exp
);
411 nf_ct_expect_put(exp
);
416 /* Get rid of expecteds, set helpers to NULL. */
417 hlist_nulls_for_each_entry(h
, nn
, &net
->ct
.unconfirmed
, hnnode
)
419 for (i
= 0; i
< net
->ct
.htable_size
; i
++) {
420 hlist_nulls_for_each_entry(h
, nn
, &net
->ct
.hash
[i
], hnnode
)
425 void nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
)
429 mutex_lock(&nf_ct_helper_mutex
);
430 hlist_del_rcu(&me
->hnode
);
431 nf_ct_helper_count
--;
432 mutex_unlock(&nf_ct_helper_mutex
);
434 /* Make sure every nothing is still using the helper unless its a
435 * connection in the hash.
440 spin_lock_bh(&nf_conntrack_lock
);
442 __nf_conntrack_helper_unregister(me
, net
);
443 spin_unlock_bh(&nf_conntrack_lock
);
446 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister
);
448 static struct nf_ct_ext_type helper_extend __read_mostly
= {
449 .len
= sizeof(struct nf_conn_help
),
450 .align
= __alignof__(struct nf_conn_help
),
451 .id
= NF_CT_EXT_HELPER
,
454 int nf_conntrack_helper_pernet_init(struct net
*net
)
456 net
->ct
.auto_assign_helper_warned
= false;
457 net
->ct
.sysctl_auto_assign_helper
= nf_ct_auto_assign_helper
;
458 return nf_conntrack_helper_init_sysctl(net
);
461 void nf_conntrack_helper_pernet_fini(struct net
*net
)
463 nf_conntrack_helper_fini_sysctl(net
);
466 int nf_conntrack_helper_init(void)
469 nf_ct_helper_hsize
= 1; /* gets rounded up to use one page */
471 nf_ct_alloc_hashtable(&nf_ct_helper_hsize
, 0);
472 if (!nf_ct_helper_hash
)
475 ret
= nf_ct_extend_register(&helper_extend
);
477 pr_err("nf_ct_helper: Unable to register helper extension.\n");
483 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_hsize
);
487 void nf_conntrack_helper_fini(void)
489 nf_ct_extend_unregister(&helper_extend
);
490 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_hsize
);