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>
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>
32 static DEFINE_MUTEX(nf_ct_helper_mutex
);
33 static struct hlist_head
*nf_ct_helper_hash __read_mostly
;
34 static unsigned int nf_ct_helper_hsize __read_mostly
;
35 static unsigned int nf_ct_helper_count __read_mostly
;
36 static int nf_ct_helper_vmalloc
;
39 /* Stupid hash, but collision free for the default registrations of the
40 * helpers currently in the kernel. */
41 static unsigned int helper_hash(const struct nf_conntrack_tuple
*tuple
)
43 return (((tuple
->src
.l3num
<< 8) | tuple
->dst
.protonum
) ^
44 (__force __u16
)tuple
->src
.u
.all
) % nf_ct_helper_hsize
;
47 struct nf_conntrack_helper
*
48 __nf_ct_helper_find(const struct nf_conntrack_tuple
*tuple
)
50 struct nf_conntrack_helper
*helper
;
51 struct nf_conntrack_tuple_mask mask
= { .src
.u
.all
= htons(0xFFFF) };
55 if (!nf_ct_helper_count
)
58 h
= helper_hash(tuple
);
59 hlist_for_each_entry_rcu(helper
, n
, &nf_ct_helper_hash
[h
], hnode
) {
60 if (nf_ct_tuple_src_mask_cmp(tuple
, &helper
->tuple
, &mask
))
65 EXPORT_SYMBOL_GPL(__nf_ct_helper_find
);
67 struct nf_conntrack_helper
*
68 __nf_conntrack_helper_find_byname(const char *name
)
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
))
82 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find_byname
);
84 struct nf_conn_help
*nf_ct_helper_ext_add(struct nf_conn
*ct
, gfp_t gfp
)
86 struct nf_conn_help
*help
;
88 help
= nf_ct_ext_add(ct
, NF_CT_EXT_HELPER
, gfp
);
90 INIT_HLIST_HEAD(&help
->expectations
);
92 pr_debug("failed to add helper extension area");
95 EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add
);
97 static inline int unhelp(struct nf_conntrack_tuple_hash
*i
,
98 const struct nf_conntrack_helper
*me
)
100 struct nf_conn
*ct
= nf_ct_tuplehash_to_ctrack(i
);
101 struct nf_conn_help
*help
= nfct_help(ct
);
103 if (help
&& help
->helper
== me
) {
104 nf_conntrack_event(IPCT_HELPER
, ct
);
105 rcu_assign_pointer(help
->helper
, NULL
);
110 int nf_conntrack_helper_register(struct nf_conntrack_helper
*me
)
112 unsigned int h
= helper_hash(&me
->tuple
);
114 BUG_ON(me
->expect_policy
== NULL
);
115 BUG_ON(me
->expect_class_max
>= NF_CT_MAX_EXPECT_CLASSES
);
117 mutex_lock(&nf_ct_helper_mutex
);
118 hlist_add_head_rcu(&me
->hnode
, &nf_ct_helper_hash
[h
]);
119 nf_ct_helper_count
++;
120 mutex_unlock(&nf_ct_helper_mutex
);
124 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register
);
126 void nf_conntrack_helper_unregister(struct nf_conntrack_helper
*me
)
128 struct nf_conntrack_tuple_hash
*h
;
129 struct nf_conntrack_expect
*exp
;
130 const struct hlist_node
*n
, *next
;
133 mutex_lock(&nf_ct_helper_mutex
);
134 hlist_del_rcu(&me
->hnode
);
135 nf_ct_helper_count
--;
136 mutex_unlock(&nf_ct_helper_mutex
);
138 /* Make sure every nothing is still using the helper unless its a
139 * connection in the hash.
143 spin_lock_bh(&nf_conntrack_lock
);
145 /* Get rid of expectations */
146 for (i
= 0; i
< nf_ct_expect_hsize
; i
++) {
147 hlist_for_each_entry_safe(exp
, n
, next
,
148 &nf_ct_expect_hash
[i
], hnode
) {
149 struct nf_conn_help
*help
= nfct_help(exp
->master
);
150 if ((help
->helper
== me
|| exp
->helper
== me
) &&
151 del_timer(&exp
->timeout
)) {
152 nf_ct_unlink_expect(exp
);
153 nf_ct_expect_put(exp
);
158 /* Get rid of expecteds, set helpers to NULL. */
159 hlist_for_each_entry(h
, n
, &unconfirmed
, hnode
)
161 for (i
= 0; i
< nf_conntrack_htable_size
; i
++) {
162 hlist_for_each_entry(h
, n
, &nf_conntrack_hash
[i
], hnode
)
165 spin_unlock_bh(&nf_conntrack_lock
);
167 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister
);
169 static struct nf_ct_ext_type helper_extend __read_mostly
= {
170 .len
= sizeof(struct nf_conn_help
),
171 .align
= __alignof__(struct nf_conn_help
),
172 .id
= NF_CT_EXT_HELPER
,
175 int nf_conntrack_helper_init(void)
179 nf_ct_helper_hsize
= 1; /* gets rounded up to use one page */
180 nf_ct_helper_hash
= nf_ct_alloc_hashtable(&nf_ct_helper_hsize
,
181 &nf_ct_helper_vmalloc
);
182 if (!nf_ct_helper_hash
)
185 err
= nf_ct_extend_register(&helper_extend
);
192 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_vmalloc
,
197 void nf_conntrack_helper_fini(void)
199 nf_ct_extend_unregister(&helper_extend
);
200 nf_ct_free_hashtable(nf_ct_helper_hash
, nf_ct_helper_vmalloc
,