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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> | |
2ba4cc31 | 23 | #include <linux/rculist.h> |
efb9a8c2 | 24 | #include <linux/rtnetlink.h> |
7e5d03bb | 25 | |
7e5d03bb MJ |
26 | #include <net/netfilter/nf_conntrack.h> |
27 | #include <net/netfilter/nf_conntrack_l3proto.h> | |
605dcad6 | 28 | #include <net/netfilter/nf_conntrack_l4proto.h> |
7e5d03bb MJ |
29 | #include <net/netfilter/nf_conntrack_helper.h> |
30 | #include <net/netfilter/nf_conntrack_core.h> | |
ceceae1b | 31 | #include <net/netfilter/nf_conntrack_extend.h> |
7e5d03bb | 32 | |
58a3c9bb | 33 | static DEFINE_MUTEX(nf_ct_helper_mutex); |
b8a7fe6c PM |
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; | |
38 | ||
39 | ||
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) | |
43 | { | |
44 | return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^ | |
a34c4589 | 45 | (__force __u16)tuple->src.u.all) % nf_ct_helper_hsize; |
b8a7fe6c | 46 | } |
7e5d03bb | 47 | |
226c0c0e | 48 | static struct nf_conntrack_helper * |
7e5d03bb MJ |
49 | __nf_ct_helper_find(const struct nf_conntrack_tuple *tuple) |
50 | { | |
b8a7fe6c | 51 | struct nf_conntrack_helper *helper; |
d4156e8c | 52 | struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) }; |
b8a7fe6c PM |
53 | struct hlist_node *n; |
54 | unsigned int h; | |
7e5d03bb | 55 | |
b8a7fe6c PM |
56 | if (!nf_ct_helper_count) |
57 | return NULL; | |
58 | ||
59 | h = helper_hash(tuple); | |
58a3c9bb | 60 | hlist_for_each_entry_rcu(helper, n, &nf_ct_helper_hash[h], hnode) { |
b8a7fe6c PM |
61 | if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask)) |
62 | return helper; | |
7e5d03bb MJ |
63 | } |
64 | return NULL; | |
65 | } | |
7e5d03bb MJ |
66 | |
67 | struct nf_conntrack_helper * | |
794e6871 | 68 | __nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum) |
7e5d03bb MJ |
69 | { |
70 | struct nf_conntrack_helper *h; | |
b8a7fe6c PM |
71 | struct hlist_node *n; |
72 | unsigned int i; | |
7e5d03bb | 73 | |
b8a7fe6c | 74 | for (i = 0; i < nf_ct_helper_hsize; i++) { |
58a3c9bb | 75 | hlist_for_each_entry_rcu(h, n, &nf_ct_helper_hash[i], hnode) { |
794e6871 PM |
76 | if (!strcmp(h->name, name) && |
77 | h->tuple.src.l3num == l3num && | |
78 | h->tuple.dst.protonum == protonum) | |
b8a7fe6c PM |
79 | return h; |
80 | } | |
7e5d03bb | 81 | } |
7e5d03bb MJ |
82 | return NULL; |
83 | } | |
794e6871 | 84 | EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find); |
7e5d03bb | 85 | |
84f3bb9a PM |
86 | struct nf_conntrack_helper * |
87 | nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum) | |
88 | { | |
89 | struct nf_conntrack_helper *h; | |
90 | ||
91 | h = __nf_conntrack_helper_find(name, l3num, protonum); | |
92 | #ifdef CONFIG_MODULES | |
93 | if (h == NULL) { | |
94 | if (request_module("nfct-helper-%s", name) == 0) | |
95 | h = __nf_conntrack_helper_find(name, l3num, protonum); | |
96 | } | |
97 | #endif | |
98 | if (h != NULL && !try_module_get(h->me)) | |
99 | h = NULL; | |
100 | ||
101 | return h; | |
102 | } | |
103 | EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get); | |
104 | ||
b560580a PM |
105 | struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp) |
106 | { | |
107 | struct nf_conn_help *help; | |
108 | ||
109 | help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp); | |
110 | if (help) | |
111 | INIT_HLIST_HEAD(&help->expectations); | |
112 | else | |
113 | pr_debug("failed to add helper extension area"); | |
114 | return help; | |
115 | } | |
116 | EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add); | |
117 | ||
b2a15a60 PM |
118 | int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl, |
119 | gfp_t flags) | |
226c0c0e | 120 | { |
b2a15a60 PM |
121 | struct nf_conntrack_helper *helper = NULL; |
122 | struct nf_conn_help *help; | |
226c0c0e | 123 | int ret = 0; |
226c0c0e | 124 | |
b2a15a60 PM |
125 | if (tmpl != NULL) { |
126 | help = nfct_help(tmpl); | |
127 | if (help != NULL) | |
128 | helper = help->helper; | |
129 | } | |
130 | ||
131 | help = nfct_help(ct); | |
132 | if (helper == NULL) | |
133 | helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple); | |
226c0c0e PNA |
134 | if (helper == NULL) { |
135 | if (help) | |
136 | rcu_assign_pointer(help->helper, NULL); | |
137 | goto out; | |
138 | } | |
139 | ||
140 | if (help == NULL) { | |
141 | help = nf_ct_helper_ext_add(ct, flags); | |
142 | if (help == NULL) { | |
143 | ret = -ENOMEM; | |
144 | goto out; | |
145 | } | |
146 | } else { | |
147 | memset(&help->help, 0, sizeof(help->help)); | |
148 | } | |
149 | ||
150 | rcu_assign_pointer(help->helper, helper); | |
151 | out: | |
152 | return ret; | |
153 | } | |
154 | EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper); | |
155 | ||
7e5d03bb MJ |
156 | static inline int unhelp(struct nf_conntrack_tuple_hash *i, |
157 | const struct nf_conntrack_helper *me) | |
158 | { | |
159 | struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i); | |
160 | struct nf_conn_help *help = nfct_help(ct); | |
161 | ||
162 | if (help && help->helper == me) { | |
163 | nf_conntrack_event(IPCT_HELPER, ct); | |
3c158f7f | 164 | rcu_assign_pointer(help->helper, NULL); |
7e5d03bb MJ |
165 | } |
166 | return 0; | |
167 | } | |
168 | ||
9858a3ae PNA |
169 | void nf_ct_helper_destroy(struct nf_conn *ct) |
170 | { | |
171 | struct nf_conn_help *help = nfct_help(ct); | |
172 | struct nf_conntrack_helper *helper; | |
173 | ||
174 | if (help) { | |
175 | rcu_read_lock(); | |
176 | helper = rcu_dereference(help->helper); | |
177 | if (helper && helper->destroy) | |
178 | helper->destroy(ct); | |
179 | rcu_read_unlock(); | |
180 | } | |
181 | } | |
182 | ||
7e5d03bb MJ |
183 | int nf_conntrack_helper_register(struct nf_conntrack_helper *me) |
184 | { | |
b8a7fe6c PM |
185 | unsigned int h = helper_hash(&me->tuple); |
186 | ||
6002f266 PM |
187 | BUG_ON(me->expect_policy == NULL); |
188 | BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES); | |
af9d32ad | 189 | BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1); |
7e5d03bb | 190 | |
58a3c9bb PM |
191 | mutex_lock(&nf_ct_helper_mutex); |
192 | hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]); | |
b8a7fe6c | 193 | nf_ct_helper_count++; |
58a3c9bb | 194 | mutex_unlock(&nf_ct_helper_mutex); |
7e5d03bb MJ |
195 | |
196 | return 0; | |
197 | } | |
13b18339 | 198 | EXPORT_SYMBOL_GPL(nf_conntrack_helper_register); |
7e5d03bb | 199 | |
68047937 AD |
200 | static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me, |
201 | struct net *net) | |
7e5d03bb | 202 | { |
7e5d03bb | 203 | struct nf_conntrack_tuple_hash *h; |
31f15875 | 204 | struct nf_conntrack_expect *exp; |
58c0fb0d | 205 | const struct hlist_node *n, *next; |
ea781f19 | 206 | const struct hlist_nulls_node *nn; |
31f15875 | 207 | unsigned int i; |
7e5d03bb | 208 | |
7e5d03bb | 209 | /* Get rid of expectations */ |
31f15875 PM |
210 | for (i = 0; i < nf_ct_expect_hsize; i++) { |
211 | hlist_for_each_entry_safe(exp, n, next, | |
68047937 | 212 | &net->ct.expect_hash[i], hnode) { |
31f15875 PM |
213 | struct nf_conn_help *help = nfct_help(exp->master); |
214 | if ((help->helper == me || exp->helper == me) && | |
215 | del_timer(&exp->timeout)) { | |
216 | nf_ct_unlink_expect(exp); | |
217 | nf_ct_expect_put(exp); | |
218 | } | |
7e5d03bb MJ |
219 | } |
220 | } | |
221 | ||
222 | /* Get rid of expecteds, set helpers to NULL. */ | |
38fb0afc | 223 | hlist_nulls_for_each_entry(h, nn, &net->ct.unconfirmed, hnnode) |
7e5d03bb | 224 | unhelp(h, me); |
d696c7bd | 225 | for (i = 0; i < net->ct.htable_size; i++) { |
ea781f19 | 226 | hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode) |
7e5d03bb MJ |
227 | unhelp(h, me); |
228 | } | |
68047937 AD |
229 | } |
230 | ||
231 | void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me) | |
232 | { | |
233 | struct net *net; | |
234 | ||
235 | mutex_lock(&nf_ct_helper_mutex); | |
236 | hlist_del_rcu(&me->hnode); | |
237 | nf_ct_helper_count--; | |
238 | mutex_unlock(&nf_ct_helper_mutex); | |
239 | ||
240 | /* Make sure every nothing is still using the helper unless its a | |
241 | * connection in the hash. | |
242 | */ | |
243 | synchronize_rcu(); | |
244 | ||
efb9a8c2 | 245 | rtnl_lock(); |
68047937 AD |
246 | spin_lock_bh(&nf_conntrack_lock); |
247 | for_each_net(net) | |
248 | __nf_conntrack_helper_unregister(me, net); | |
f8ba1aff | 249 | spin_unlock_bh(&nf_conntrack_lock); |
efb9a8c2 | 250 | rtnl_unlock(); |
7e5d03bb | 251 | } |
13b18339 | 252 | EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister); |
ceceae1b | 253 | |
61eb3107 | 254 | static struct nf_ct_ext_type helper_extend __read_mostly = { |
ceceae1b YK |
255 | .len = sizeof(struct nf_conn_help), |
256 | .align = __alignof__(struct nf_conn_help), | |
257 | .id = NF_CT_EXT_HELPER, | |
258 | }; | |
259 | ||
8d4bc5b6 | 260 | int nf_conntrack_helper_init(void) |
ceceae1b | 261 | { |
b8a7fe6c PM |
262 | int err; |
263 | ||
264 | nf_ct_helper_hsize = 1; /* gets rounded up to use one page */ | |
265 | nf_ct_helper_hash = nf_ct_alloc_hashtable(&nf_ct_helper_hsize, | |
ea781f19 | 266 | &nf_ct_helper_vmalloc, 0); |
b8a7fe6c PM |
267 | if (!nf_ct_helper_hash) |
268 | return -ENOMEM; | |
269 | ||
270 | err = nf_ct_extend_register(&helper_extend); | |
271 | if (err < 0) | |
272 | goto err1; | |
273 | ||
274 | return 0; | |
275 | ||
276 | err1: | |
277 | nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_vmalloc, | |
278 | nf_ct_helper_hsize); | |
279 | return err; | |
ceceae1b YK |
280 | } |
281 | ||
8d4bc5b6 | 282 | void nf_conntrack_helper_fini(void) |
ceceae1b YK |
283 | { |
284 | nf_ct_extend_unregister(&helper_extend); | |
b8a7fe6c PM |
285 | nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_vmalloc, |
286 | nf_ct_helper_hsize); | |
ceceae1b | 287 | } |