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 #define ASSERT_READ_LOCK(x)
25 #define ASSERT_WRITE_LOCK(x)
27 #include <net/netfilter/nf_conntrack.h>
28 #include <net/netfilter/nf_conntrack_l3proto.h>
29 #include <net/netfilter/nf_conntrack_l4proto.h>
30 #include <net/netfilter/nf_conntrack_helper.h>
31 #include <net/netfilter/nf_conntrack_core.h>
33 static __read_mostly
LIST_HEAD(helpers
);
35 struct nf_conntrack_helper
*
36 __nf_ct_helper_find(const struct nf_conntrack_tuple
*tuple
)
38 struct nf_conntrack_helper
*h
;
40 list_for_each_entry(h
, &helpers
, list
) {
41 if (nf_ct_tuple_mask_cmp(tuple
, &h
->tuple
, &h
->mask
))
47 struct nf_conntrack_helper
*
48 nf_ct_helper_find_get( const struct nf_conntrack_tuple
*tuple
)
50 struct nf_conntrack_helper
*helper
;
52 /* need nf_conntrack_lock to assure that helper exists until
53 * try_module_get() is called */
54 read_lock_bh(&nf_conntrack_lock
);
56 helper
= __nf_ct_helper_find(tuple
);
58 /* need to increase module usage count to assure helper will
59 * not go away while the caller is e.g. busy putting a
60 * conntrack in the hash that uses the helper */
61 if (!try_module_get(helper
->me
))
65 read_unlock_bh(&nf_conntrack_lock
);
70 void nf_ct_helper_put(struct nf_conntrack_helper
*helper
)
72 module_put(helper
->me
);
75 struct nf_conntrack_helper
*
76 __nf_conntrack_helper_find_byname(const char *name
)
78 struct nf_conntrack_helper
*h
;
80 list_for_each_entry(h
, &helpers
, list
) {
81 if (!strcmp(h
->name
, name
))
88 static inline int unhelp(struct nf_conntrack_tuple_hash
*i
,
89 const struct nf_conntrack_helper
*me
)
91 struct nf_conn
*ct
= nf_ct_tuplehash_to_ctrack(i
);
92 struct nf_conn_help
*help
= nfct_help(ct
);
94 if (help
&& help
->helper
== me
) {
95 nf_conntrack_event(IPCT_HELPER
, ct
);
101 int nf_conntrack_helper_register(struct nf_conntrack_helper
*me
)
104 BUG_ON(me
->timeout
== 0);
106 ret
= nf_conntrack_register_cache(NF_CT_F_HELP
, "nf_conntrack:help",
107 sizeof(struct nf_conn
)
108 + sizeof(struct nf_conn_help
)
109 + __alignof__(struct nf_conn_help
));
111 printk(KERN_ERR
"nf_conntrack_helper_register: Unable to create slab cache for conntracks\n");
114 write_lock_bh(&nf_conntrack_lock
);
115 list_add(&me
->list
, &helpers
);
116 write_unlock_bh(&nf_conntrack_lock
);
121 void nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
)
124 struct nf_conntrack_tuple_hash
*h
;
125 struct nf_conntrack_expect
*exp
, *tmp
;
127 /* Need write lock here, to delete helper. */
128 write_lock_bh(&nf_conntrack_lock
);
131 /* Get rid of expectations */
132 list_for_each_entry_safe(exp
, tmp
, &nf_conntrack_expect_list
, list
) {
133 struct nf_conn_help
*help
= nfct_help(exp
->master
);
134 if (help
->helper
== me
&& del_timer(&exp
->timeout
)) {
135 nf_ct_unlink_expect(exp
);
136 nf_conntrack_expect_put(exp
);
140 /* Get rid of expecteds, set helpers to NULL. */
141 list_for_each_entry(h
, &unconfirmed
, list
)
143 for (i
= 0; i
< nf_conntrack_htable_size
; i
++) {
144 list_for_each_entry(h
, &nf_conntrack_hash
[i
], list
)
147 write_unlock_bh(&nf_conntrack_lock
);
149 /* Someone could be still looking at the helper in a bh. */