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>
31 #include <net/netfilter/nf_log.h>
33 static DEFINE_MUTEX(nf_ct_helper_mutex
);
34 struct hlist_head
*nf_ct_helper_hash __read_mostly
;
35 EXPORT_SYMBOL_GPL(nf_ct_helper_hash
);
36 unsigned int nf_ct_helper_hsize __read_mostly
;
37 EXPORT_SYMBOL_GPL(nf_ct_helper_hsize
);
38 static unsigned int nf_ct_helper_count __read_mostly
;
40 static bool nf_ct_auto_assign_helper __read_mostly
= true;
41 module_param_named(nf_conntrack_helper
, nf_ct_auto_assign_helper
, bool, 0644);
42 MODULE_PARM_DESC(nf_conntrack_helper
,
43 "Enable automatic conntrack helper assignment (default 1)");
46 static struct ctl_table helper_sysctl_table
[] = {
48 .procname
= "nf_conntrack_helper",
49 .data
= &init_net
.ct
.sysctl_auto_assign_helper
,
50 .maxlen
= sizeof(unsigned int),
52 .proc_handler
= proc_dointvec
,
57 static int nf_conntrack_helper_init_sysctl(struct net
*net
)
59 struct ctl_table
*table
;
61 table
= kmemdup(helper_sysctl_table
, sizeof(helper_sysctl_table
),
66 table
[0].data
= &net
->ct
.sysctl_auto_assign_helper
;
68 /* Don't export sysctls to unprivileged users */
69 if (net
->user_ns
!= &init_user_ns
)
70 table
[0].procname
= NULL
;
72 net
->ct
.helper_sysctl_header
=
73 register_net_sysctl(net
, "net/netfilter", table
);
75 if (!net
->ct
.helper_sysctl_header
) {
76 pr_err("nf_conntrack_helper: can't register to sysctl.\n");
87 static void nf_conntrack_helper_fini_sysctl(struct net
*net
)
89 struct ctl_table
*table
;
91 table
= net
->ct
.helper_sysctl_header
->ctl_table_arg
;
92 unregister_net_sysctl_table(net
->ct
.helper_sysctl_header
);
96 static int nf_conntrack_helper_init_sysctl(struct net
*net
)
101 static void nf_conntrack_helper_fini_sysctl(struct net
*net
)
104 #endif /* CONFIG_SYSCTL */
106 /* Stupid hash, but collision free for the default registrations of the
107 * helpers currently in the kernel. */
108 static unsigned int helper_hash(const struct nf_conntrack_tuple
*tuple
)
110 return (((tuple
->src
.l3num
<< 8) | tuple
->dst
.protonum
) ^
111 (__force __u16
)tuple
->src
.u
.all
) % nf_ct_helper_hsize
;
114 static struct nf_conntrack_helper
*
115 __nf_ct_helper_find(const struct nf_conntrack_tuple
*tuple
)
117 struct nf_conntrack_helper
*helper
;
118 struct nf_conntrack_tuple_mask mask
= { .src
.u
.all
= htons(0xFFFF) };
119 struct hlist_node
*n
;
122 if (!nf_ct_helper_count
)
125 h
= helper_hash(tuple
);
126 hlist_for_each_entry_rcu(helper
, n
, &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
;
137 struct hlist_node
*n
;
140 for (i
= 0; i
< nf_ct_helper_hsize
; i
++) {
141 hlist_for_each_entry_rcu(h
, n
, &nf_ct_helper_hash
[i
], hnode
) {
142 if (!strcmp(h
->name
, name
) &&
143 h
->tuple
.src
.l3num
== l3num
&&
144 h
->tuple
.dst
.protonum
== protonum
)
150 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find
);
152 struct nf_conntrack_helper
*
153 nf_conntrack_helper_try_module_get(const char *name
, u16 l3num
, u8 protonum
)
155 struct nf_conntrack_helper
*h
;
157 h
= __nf_conntrack_helper_find(name
, l3num
, protonum
);
158 #ifdef CONFIG_MODULES
160 if (request_module("nfct-helper-%s", name
) == 0)
161 h
= __nf_conntrack_helper_find(name
, l3num
, protonum
);
164 if (h
!= NULL
&& !try_module_get(h
->me
))
169 EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get
);
171 struct nf_conn_help
*
172 nf_ct_helper_ext_add(struct nf_conn
*ct
,
173 struct nf_conntrack_helper
*helper
, gfp_t gfp
)
175 struct nf_conn_help
*help
;
177 help
= nf_ct_ext_add_length(ct
, NF_CT_EXT_HELPER
,
178 helper
->data_len
, gfp
);
180 INIT_HLIST_HEAD(&help
->expectations
);
182 pr_debug("failed to add helper extension area");
185 EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add
);
187 int __nf_ct_try_assign_helper(struct nf_conn
*ct
, struct nf_conn
*tmpl
,
190 struct nf_conntrack_helper
*helper
= NULL
;
191 struct nf_conn_help
*help
;
192 struct net
*net
= nf_ct_net(ct
);
195 /* We already got a helper explicitly attached. The function
196 * nf_conntrack_alter_reply - in case NAT is in use - asks for looking
197 * the helper up again. Since now the user is in full control of
198 * making consistent helper configurations, skip this automatic
199 * re-lookup, otherwise we'll lose the helper.
201 if (test_bit(IPS_HELPER_BIT
, &ct
->status
))
205 help
= nfct_help(tmpl
);
207 helper
= help
->helper
;
208 set_bit(IPS_HELPER_BIT
, &ct
->status
);
212 help
= nfct_help(ct
);
213 if (net
->ct
.sysctl_auto_assign_helper
&& helper
== NULL
) {
214 helper
= __nf_ct_helper_find(&ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
);
215 if (unlikely(!net
->ct
.auto_assign_helper_warned
&& helper
)) {
216 pr_info("nf_conntrack: automatic helper "
217 "assignment is deprecated and it will "
218 "be removed soon. Use the iptables CT target "
219 "to attach helpers instead.\n");
220 net
->ct
.auto_assign_helper_warned
= true;
224 if (helper
== NULL
) {
226 RCU_INIT_POINTER(help
->helper
, NULL
);
231 help
= nf_ct_helper_ext_add(ct
, helper
, flags
);
237 /* We only allow helper re-assignment of the same sort since
238 * we cannot reallocate the helper extension area.
240 struct nf_conntrack_helper
*tmp
= rcu_dereference(help
->helper
);
242 if (tmp
&& tmp
->help
!= helper
->help
) {
243 RCU_INIT_POINTER(help
->helper
, NULL
);
248 rcu_assign_pointer(help
->helper
, helper
);
252 EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper
);
254 static inline int unhelp(struct nf_conntrack_tuple_hash
*i
,
255 const struct nf_conntrack_helper
*me
)
257 struct nf_conn
*ct
= nf_ct_tuplehash_to_ctrack(i
);
258 struct nf_conn_help
*help
= nfct_help(ct
);
260 if (help
&& rcu_dereference_protected(
262 lockdep_is_held(&nf_conntrack_lock
)
264 nf_conntrack_event(IPCT_HELPER
, ct
);
265 RCU_INIT_POINTER(help
->helper
, NULL
);
270 void nf_ct_helper_destroy(struct nf_conn
*ct
)
272 struct nf_conn_help
*help
= nfct_help(ct
);
273 struct nf_conntrack_helper
*helper
;
277 helper
= rcu_dereference(help
->helper
);
278 if (helper
&& helper
->destroy
)
284 static LIST_HEAD(nf_ct_helper_expectfn_list
);
286 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn
*n
)
288 spin_lock_bh(&nf_conntrack_lock
);
289 list_add_rcu(&n
->head
, &nf_ct_helper_expectfn_list
);
290 spin_unlock_bh(&nf_conntrack_lock
);
292 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register
);
294 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn
*n
)
296 spin_lock_bh(&nf_conntrack_lock
);
297 list_del_rcu(&n
->head
);
298 spin_unlock_bh(&nf_conntrack_lock
);
300 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister
);
302 struct nf_ct_helper_expectfn
*
303 nf_ct_helper_expectfn_find_by_name(const char *name
)
305 struct nf_ct_helper_expectfn
*cur
;
309 list_for_each_entry_rcu(cur
, &nf_ct_helper_expectfn_list
, head
) {
310 if (!strcmp(cur
->name
, name
)) {
316 return found
? cur
: NULL
;
318 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name
);
320 struct nf_ct_helper_expectfn
*
321 nf_ct_helper_expectfn_find_by_symbol(const void *symbol
)
323 struct nf_ct_helper_expectfn
*cur
;
327 list_for_each_entry_rcu(cur
, &nf_ct_helper_expectfn_list
, head
) {
328 if (cur
->expectfn
== symbol
) {
334 return found
? cur
: NULL
;
336 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol
);
339 void nf_ct_helper_log(struct sk_buff
*skb
, const struct nf_conn
*ct
,
340 const char *fmt
, ...)
342 const struct nf_conn_help
*help
;
343 const struct nf_conntrack_helper
*helper
;
345 /* Called from the helper function, this call never fails */
346 help
= nfct_help(ct
);
348 /* rcu_read_lock()ed by nf_hook_slow */
349 helper
= rcu_dereference(help
->helper
);
351 nf_log_packet(nf_ct_l3num(ct
), 0, skb
, NULL
, NULL
, NULL
,
352 "nf_ct_%s: dropping packet: %s ", helper
->name
, fmt
);
354 EXPORT_SYMBOL_GPL(nf_ct_helper_log
);
356 int nf_conntrack_helper_register(struct nf_conntrack_helper
*me
)
359 struct nf_conntrack_helper
*cur
;
360 struct hlist_node
*n
;
361 unsigned int h
= helper_hash(&me
->tuple
);
363 BUG_ON(me
->expect_policy
== NULL
);
364 BUG_ON(me
->expect_class_max
>= NF_CT_MAX_EXPECT_CLASSES
);
365 BUG_ON(strlen(me
->name
) > NF_CT_HELPER_NAME_LEN
- 1);
367 mutex_lock(&nf_ct_helper_mutex
);
368 hlist_for_each_entry(cur
, n
, &nf_ct_helper_hash
[h
], hnode
) {
369 if (strncmp(cur
->name
, me
->name
, NF_CT_HELPER_NAME_LEN
) == 0 &&
370 cur
->tuple
.src
.l3num
== me
->tuple
.src
.l3num
&&
371 cur
->tuple
.dst
.protonum
== me
->tuple
.dst
.protonum
) {
376 hlist_add_head_rcu(&me
->hnode
, &nf_ct_helper_hash
[h
]);
377 nf_ct_helper_count
++;
379 mutex_unlock(&nf_ct_helper_mutex
);
382 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register
);
384 static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
,
387 struct nf_conntrack_tuple_hash
*h
;
388 struct nf_conntrack_expect
*exp
;
389 const struct hlist_node
*n
, *next
;
390 const struct hlist_nulls_node
*nn
;
393 /* Get rid of expectations */
394 for (i
= 0; i
< nf_ct_expect_hsize
; i
++) {
395 hlist_for_each_entry_safe(exp
, n
, next
,
396 &net
->ct
.expect_hash
[i
], hnode
) {
397 struct nf_conn_help
*help
= nfct_help(exp
->master
);
398 if ((rcu_dereference_protected(
400 lockdep_is_held(&nf_conntrack_lock
)
401 ) == me
|| exp
->helper
== me
) &&
402 del_timer(&exp
->timeout
)) {
403 nf_ct_unlink_expect(exp
);
404 nf_ct_expect_put(exp
);
409 /* Get rid of expecteds, set helpers to NULL. */
410 hlist_nulls_for_each_entry(h
, nn
, &net
->ct
.unconfirmed
, hnnode
)
412 for (i
= 0; i
< net
->ct
.htable_size
; i
++) {
413 hlist_nulls_for_each_entry(h
, nn
, &net
->ct
.hash
[i
], hnnode
)
418 void nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
)
422 mutex_lock(&nf_ct_helper_mutex
);
423 hlist_del_rcu(&me
->hnode
);
424 nf_ct_helper_count
--;
425 mutex_unlock(&nf_ct_helper_mutex
);
427 /* Make sure every nothing is still using the helper unless its a
428 * connection in the hash.
433 spin_lock_bh(&nf_conntrack_lock
);
435 __nf_conntrack_helper_unregister(me
, net
);
436 spin_unlock_bh(&nf_conntrack_lock
);
439 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister
);
441 static struct nf_ct_ext_type helper_extend __read_mostly
= {
442 .len
= sizeof(struct nf_conn_help
),
443 .align
= __alignof__(struct nf_conn_help
),
444 .id
= NF_CT_EXT_HELPER
,
447 int nf_conntrack_helper_pernet_init(struct net
*net
)
449 net
->ct
.auto_assign_helper_warned
= false;
450 net
->ct
.sysctl_auto_assign_helper
= nf_ct_auto_assign_helper
;
451 return nf_conntrack_helper_init_sysctl(net
);
454 void nf_conntrack_helper_pernet_fini(struct net
*net
)
456 nf_conntrack_helper_fini_sysctl(net
);
459 int nf_conntrack_helper_init(void)
462 nf_ct_helper_hsize
= 1; /* gets rounded up to use one page */
464 nf_ct_alloc_hashtable(&nf_ct_helper_hsize
, 0);
465 if (!nf_ct_helper_hash
)
468 ret
= nf_ct_extend_register(&helper_extend
);
470 pr_err("nf_ct_helper: Unable to register helper extension.\n");
476 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_hsize
);
480 void nf_conntrack_helper_fini(void)
482 nf_ct_extend_unregister(&helper_extend
);
483 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_hsize
);