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>
24 #include <net/netfilter/nf_conntrack.h>
25 #include <net/netfilter/nf_conntrack_l3proto.h>
26 #include <net/netfilter/nf_conntrack_l4proto.h>
27 #include <net/netfilter/nf_conntrack_helper.h>
28 #include <net/netfilter/nf_conntrack_core.h>
29 #include <net/netfilter/nf_conntrack_extend.h>
31 static __read_mostly
LIST_HEAD(helpers
);
33 struct nf_conntrack_helper
*
34 __nf_ct_helper_find(const struct nf_conntrack_tuple
*tuple
)
36 struct nf_conntrack_helper
*h
;
37 struct nf_conntrack_tuple_mask mask
= { .src
.u
.all
= htons(0xFFFF) };
39 list_for_each_entry(h
, &helpers
, list
) {
40 if (nf_ct_tuple_src_mask_cmp(tuple
, &h
->tuple
, &mask
))
46 struct nf_conntrack_helper
*
47 nf_ct_helper_find_get( const struct nf_conntrack_tuple
*tuple
)
49 struct nf_conntrack_helper
*helper
;
51 /* need nf_conntrack_lock to assure that helper exists until
52 * try_module_get() is called */
53 read_lock_bh(&nf_conntrack_lock
);
55 helper
= __nf_ct_helper_find(tuple
);
57 /* need to increase module usage count to assure helper will
58 * not go away while the caller is e.g. busy putting a
59 * conntrack in the hash that uses the helper */
60 if (!try_module_get(helper
->me
))
64 read_unlock_bh(&nf_conntrack_lock
);
68 EXPORT_SYMBOL_GPL(nf_ct_helper_find_get
);
70 void nf_ct_helper_put(struct nf_conntrack_helper
*helper
)
72 module_put(helper
->me
);
74 EXPORT_SYMBOL_GPL(nf_ct_helper_put
);
76 struct nf_conntrack_helper
*
77 __nf_conntrack_helper_find_byname(const char *name
)
79 struct nf_conntrack_helper
*h
;
81 list_for_each_entry(h
, &helpers
, list
) {
82 if (!strcmp(h
->name
, name
))
88 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find_byname
);
90 static inline int unhelp(struct nf_conntrack_tuple_hash
*i
,
91 const struct nf_conntrack_helper
*me
)
93 struct nf_conn
*ct
= nf_ct_tuplehash_to_ctrack(i
);
94 struct nf_conn_help
*help
= nfct_help(ct
);
96 if (help
&& help
->helper
== me
) {
97 nf_conntrack_event(IPCT_HELPER
, ct
);
98 rcu_assign_pointer(help
->helper
, NULL
);
103 int nf_conntrack_helper_register(struct nf_conntrack_helper
*me
)
105 BUG_ON(me
->timeout
== 0);
107 write_lock_bh(&nf_conntrack_lock
);
108 list_add(&me
->list
, &helpers
);
109 write_unlock_bh(&nf_conntrack_lock
);
113 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register
);
115 void nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
)
118 struct nf_conntrack_tuple_hash
*h
;
119 struct nf_conntrack_expect
*exp
, *tmp
;
120 struct hlist_node
*n
;
122 /* Need write lock here, to delete helper. */
123 write_lock_bh(&nf_conntrack_lock
);
126 /* Get rid of expectations */
127 list_for_each_entry_safe(exp
, tmp
, &nf_ct_expect_list
, list
) {
128 struct nf_conn_help
*help
= nfct_help(exp
->master
);
129 if ((help
->helper
== me
|| exp
->helper
== me
) &&
130 del_timer(&exp
->timeout
)) {
131 nf_ct_unlink_expect(exp
);
132 nf_ct_expect_put(exp
);
136 /* Get rid of expecteds, set helpers to NULL. */
137 hlist_for_each_entry(h
, n
, &unconfirmed
, hnode
)
139 for (i
= 0; i
< nf_conntrack_htable_size
; i
++) {
140 hlist_for_each_entry(h
, n
, &nf_conntrack_hash
[i
], hnode
)
143 write_unlock_bh(&nf_conntrack_lock
);
145 /* Someone could be still looking at the helper in a bh. */
148 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister
);
150 static struct nf_ct_ext_type helper_extend __read_mostly
= {
151 .len
= sizeof(struct nf_conn_help
),
152 .align
= __alignof__(struct nf_conn_help
),
153 .id
= NF_CT_EXT_HELPER
,
156 int nf_conntrack_helper_init()
158 return nf_ct_extend_register(&helper_extend
);
161 void nf_conntrack_helper_fini()
163 nf_ct_extend_unregister(&helper_extend
);