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Commit | Line | Data |
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7e5d03bb MJ |
1 | /* Helper handling for netfilter. */ |
2 | ||
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> | |
6 | * | |
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. | |
10 | */ | |
11 | ||
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 | ||
24 | #define ASSERT_READ_LOCK(x) | |
25 | #define ASSERT_WRITE_LOCK(x) | |
26 | ||
27 | #include <net/netfilter/nf_conntrack.h> | |
28 | #include <net/netfilter/nf_conntrack_l3proto.h> | |
29 | #include <net/netfilter/nf_conntrack_protocol.h> | |
30 | #include <net/netfilter/nf_conntrack_helper.h> | |
31 | #include <net/netfilter/nf_conntrack_core.h> | |
32 | ||
e2b7606c | 33 | static __read_mostly LIST_HEAD(helpers); |
7e5d03bb MJ |
34 | |
35 | struct nf_conntrack_helper * | |
36 | __nf_ct_helper_find(const struct nf_conntrack_tuple *tuple) | |
37 | { | |
38 | struct nf_conntrack_helper *h; | |
39 | ||
40 | list_for_each_entry(h, &helpers, list) { | |
41 | if (nf_ct_tuple_mask_cmp(tuple, &h->tuple, &h->mask)) | |
42 | return h; | |
43 | } | |
44 | return NULL; | |
45 | } | |
46 | ||
47 | struct nf_conntrack_helper * | |
48 | nf_ct_helper_find_get( const struct nf_conntrack_tuple *tuple) | |
49 | { | |
50 | struct nf_conntrack_helper *helper; | |
51 | ||
52 | /* need nf_conntrack_lock to assure that helper exists until | |
53 | * try_module_get() is called */ | |
54 | read_lock_bh(&nf_conntrack_lock); | |
55 | ||
56 | helper = __nf_ct_helper_find(tuple); | |
57 | if (helper) { | |
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)) | |
62 | helper = NULL; | |
63 | } | |
64 | ||
65 | read_unlock_bh(&nf_conntrack_lock); | |
66 | ||
67 | return helper; | |
68 | } | |
69 | ||
70 | void nf_ct_helper_put(struct nf_conntrack_helper *helper) | |
71 | { | |
72 | module_put(helper->me); | |
73 | } | |
74 | ||
75 | struct nf_conntrack_helper * | |
76 | __nf_conntrack_helper_find_byname(const char *name) | |
77 | { | |
78 | struct nf_conntrack_helper *h; | |
79 | ||
80 | list_for_each_entry(h, &helpers, list) { | |
81 | if (!strcmp(h->name, name)) | |
82 | return h; | |
83 | } | |
84 | ||
85 | return NULL; | |
86 | } | |
87 | ||
88 | static inline int unhelp(struct nf_conntrack_tuple_hash *i, | |
89 | const struct nf_conntrack_helper *me) | |
90 | { | |
91 | struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i); | |
92 | struct nf_conn_help *help = nfct_help(ct); | |
93 | ||
94 | if (help && help->helper == me) { | |
95 | nf_conntrack_event(IPCT_HELPER, ct); | |
96 | help->helper = NULL; | |
97 | } | |
98 | return 0; | |
99 | } | |
100 | ||
101 | int nf_conntrack_helper_register(struct nf_conntrack_helper *me) | |
102 | { | |
103 | int ret; | |
104 | BUG_ON(me->timeout == 0); | |
105 | ||
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)); | |
110 | if (ret < 0) { | |
111 | printk(KERN_ERR "nf_conntrack_helper_register: Unable to create slab cache for conntracks\n"); | |
112 | return ret; | |
113 | } | |
114 | write_lock_bh(&nf_conntrack_lock); | |
115 | list_add(&me->list, &helpers); | |
116 | write_unlock_bh(&nf_conntrack_lock); | |
117 | ||
118 | return 0; | |
119 | } | |
120 | ||
121 | void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me) | |
122 | { | |
123 | unsigned int i; | |
124 | struct nf_conntrack_tuple_hash *h; | |
125 | struct nf_conntrack_expect *exp, *tmp; | |
126 | ||
127 | /* Need write lock here, to delete helper. */ | |
128 | write_lock_bh(&nf_conntrack_lock); | |
129 | list_del(&me->list); | |
130 | ||
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); | |
137 | } | |
138 | } | |
139 | ||
140 | /* Get rid of expecteds, set helpers to NULL. */ | |
141 | list_for_each_entry(h, &unconfirmed, list) | |
142 | unhelp(h, me); | |
143 | for (i = 0; i < nf_conntrack_htable_size; i++) { | |
144 | list_for_each_entry(h, &nf_conntrack_hash[i], list) | |
145 | unhelp(h, me); | |
146 | } | |
147 | write_unlock_bh(&nf_conntrack_lock); | |
148 | ||
149 | /* Someone could be still looking at the helper in a bh. */ | |
150 | synchronize_net(); | |
151 | } |