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/slab.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>
33 static DEFINE_MUTEX(nf_ct_helper_mutex
);
34 static struct hlist_head
*nf_ct_helper_hash __read_mostly
;
35 static unsigned int nf_ct_helper_hsize __read_mostly
;
36 static unsigned int nf_ct_helper_count __read_mostly
;
37 static int nf_ct_helper_vmalloc
;
40 /* Stupid hash, but collision free for the default registrations of the
41 * helpers currently in the kernel. */
42 static unsigned int helper_hash(const struct nf_conntrack_tuple
*tuple
)
44 return (((tuple
->src
.l3num
<< 8) | tuple
->dst
.protonum
) ^
45 (__force __u16
)tuple
->src
.u
.all
) % nf_ct_helper_hsize
;
48 static struct nf_conntrack_helper
*
49 __nf_ct_helper_find(const struct nf_conntrack_tuple
*tuple
)
51 struct nf_conntrack_helper
*helper
;
52 struct nf_conntrack_tuple_mask mask
= { .src
.u
.all
= htons(0xFFFF) };
56 if (!nf_ct_helper_count
)
59 h
= helper_hash(tuple
);
60 hlist_for_each_entry_rcu(helper
, n
, &nf_ct_helper_hash
[h
], hnode
) {
61 if (nf_ct_tuple_src_mask_cmp(tuple
, &helper
->tuple
, &mask
))
67 struct nf_conntrack_helper
*
68 __nf_conntrack_helper_find(const char *name
, u16 l3num
, u8 protonum
)
70 struct nf_conntrack_helper
*h
;
74 for (i
= 0; i
< nf_ct_helper_hsize
; i
++) {
75 hlist_for_each_entry_rcu(h
, n
, &nf_ct_helper_hash
[i
], hnode
) {
76 if (!strcmp(h
->name
, name
) &&
77 h
->tuple
.src
.l3num
== l3num
&&
78 h
->tuple
.dst
.protonum
== protonum
)
84 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find
);
86 struct nf_conn_help
*nf_ct_helper_ext_add(struct nf_conn
*ct
, gfp_t gfp
)
88 struct nf_conn_help
*help
;
90 help
= nf_ct_ext_add(ct
, NF_CT_EXT_HELPER
, gfp
);
92 INIT_HLIST_HEAD(&help
->expectations
);
94 pr_debug("failed to add helper extension area");
97 EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add
);
99 int __nf_ct_try_assign_helper(struct nf_conn
*ct
, struct nf_conn
*tmpl
,
102 struct nf_conntrack_helper
*helper
= NULL
;
103 struct nf_conn_help
*help
;
107 help
= nfct_help(tmpl
);
109 helper
= help
->helper
;
112 help
= nfct_help(ct
);
114 helper
= __nf_ct_helper_find(&ct
->tuplehash
[IP_CT_DIR_REPLY
].tuple
);
115 if (helper
== NULL
) {
117 rcu_assign_pointer(help
->helper
, NULL
);
122 help
= nf_ct_helper_ext_add(ct
, flags
);
128 memset(&help
->help
, 0, sizeof(help
->help
));
131 rcu_assign_pointer(help
->helper
, helper
);
135 EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper
);
137 static inline int unhelp(struct nf_conntrack_tuple_hash
*i
,
138 const struct nf_conntrack_helper
*me
)
140 struct nf_conn
*ct
= nf_ct_tuplehash_to_ctrack(i
);
141 struct nf_conn_help
*help
= nfct_help(ct
);
143 if (help
&& help
->helper
== me
) {
144 nf_conntrack_event(IPCT_HELPER
, ct
);
145 rcu_assign_pointer(help
->helper
, NULL
);
150 void nf_ct_helper_destroy(struct nf_conn
*ct
)
152 struct nf_conn_help
*help
= nfct_help(ct
);
153 struct nf_conntrack_helper
*helper
;
157 helper
= rcu_dereference(help
->helper
);
158 if (helper
&& helper
->destroy
)
164 int nf_conntrack_helper_register(struct nf_conntrack_helper
*me
)
166 unsigned int h
= helper_hash(&me
->tuple
);
168 BUG_ON(me
->expect_policy
== NULL
);
169 BUG_ON(me
->expect_class_max
>= NF_CT_MAX_EXPECT_CLASSES
);
170 BUG_ON(strlen(me
->name
) > NF_CT_HELPER_NAME_LEN
- 1);
172 mutex_lock(&nf_ct_helper_mutex
);
173 hlist_add_head_rcu(&me
->hnode
, &nf_ct_helper_hash
[h
]);
174 nf_ct_helper_count
++;
175 mutex_unlock(&nf_ct_helper_mutex
);
179 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register
);
181 static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
,
184 struct nf_conntrack_tuple_hash
*h
;
185 struct nf_conntrack_expect
*exp
;
186 const struct hlist_node
*n
, *next
;
187 const struct hlist_nulls_node
*nn
;
190 /* Get rid of expectations */
191 for (i
= 0; i
< nf_ct_expect_hsize
; i
++) {
192 hlist_for_each_entry_safe(exp
, n
, next
,
193 &net
->ct
.expect_hash
[i
], hnode
) {
194 struct nf_conn_help
*help
= nfct_help(exp
->master
);
195 if ((help
->helper
== me
|| exp
->helper
== me
) &&
196 del_timer(&exp
->timeout
)) {
197 nf_ct_unlink_expect(exp
);
198 nf_ct_expect_put(exp
);
203 /* Get rid of expecteds, set helpers to NULL. */
204 hlist_nulls_for_each_entry(h
, nn
, &net
->ct
.unconfirmed
, hnnode
)
206 for (i
= 0; i
< nf_conntrack_htable_size
; i
++) {
207 hlist_nulls_for_each_entry(h
, nn
, &net
->ct
.hash
[i
], hnnode
)
212 void nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
)
216 mutex_lock(&nf_ct_helper_mutex
);
217 hlist_del_rcu(&me
->hnode
);
218 nf_ct_helper_count
--;
219 mutex_unlock(&nf_ct_helper_mutex
);
221 /* Make sure every nothing is still using the helper unless its a
222 * connection in the hash.
227 spin_lock_bh(&nf_conntrack_lock
);
229 __nf_conntrack_helper_unregister(me
, net
);
230 spin_unlock_bh(&nf_conntrack_lock
);
233 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister
);
235 static struct nf_ct_ext_type helper_extend __read_mostly
= {
236 .len
= sizeof(struct nf_conn_help
),
237 .align
= __alignof__(struct nf_conn_help
),
238 .id
= NF_CT_EXT_HELPER
,
241 int nf_conntrack_helper_init(void)
245 nf_ct_helper_hsize
= 1; /* gets rounded up to use one page */
246 nf_ct_helper_hash
= nf_ct_alloc_hashtable(&nf_ct_helper_hsize
,
247 &nf_ct_helper_vmalloc
, 0);
248 if (!nf_ct_helper_hash
)
251 err
= nf_ct_extend_register(&helper_extend
);
258 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_vmalloc
,
263 void nf_conntrack_helper_fini(void)
265 nf_ct_extend_unregister(&helper_extend
);
266 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_vmalloc
,