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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/random.h>
19#include <linux/err.h>
20#include <linux/kernel.h>
21#include <linux/netdevice.h>
22#include <linux/rculist.h>
23#include <linux/rtnetlink.h>
24
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>
31
32static DEFINE_MUTEX(nf_ct_helper_mutex);
33static struct hlist_head *nf_ct_helper_hash __read_mostly;
34static unsigned int nf_ct_helper_hsize __read_mostly;
35static unsigned int nf_ct_helper_count __read_mostly;
36
37
38
39
40static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
41{
42 return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
43 (__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
44}
45
46static struct nf_conntrack_helper *
47__nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
48{
49 struct nf_conntrack_helper *helper;
50 struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
51 struct hlist_node *n;
52 unsigned int h;
53
54 if (!nf_ct_helper_count)
55 return NULL;
56
57 h = helper_hash(tuple);
58 hlist_for_each_entry_rcu(helper, n, &nf_ct_helper_hash[h], hnode) {
59 if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
60 return helper;
61 }
62 return NULL;
63}
64
65struct nf_conntrack_helper *
66__nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
67{
68 struct nf_conntrack_helper *h;
69 struct hlist_node *n;
70 unsigned int i;
71
72 for (i = 0; i < nf_ct_helper_hsize; i++) {
73 hlist_for_each_entry_rcu(h, n, &nf_ct_helper_hash[i], hnode) {
74 if (!strcmp(h->name, name) &&
75 h->tuple.src.l3num == l3num &&
76 h->tuple.dst.protonum == protonum)
77 return h;
78 }
79 }
80 return NULL;
81}
82EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
83
84struct nf_conntrack_helper *
85nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
86{
87 struct nf_conntrack_helper *h;
88
89 h = __nf_conntrack_helper_find(name, l3num, protonum);
90#ifdef CONFIG_MODULES
91 if (h == NULL) {
92 if (request_module("nfct-helper-%s", name) == 0)
93 h = __nf_conntrack_helper_find(name, l3num, protonum);
94 }
95#endif
96 if (h != NULL && !try_module_get(h->me))
97 h = NULL;
98
99 return h;
100}
101EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
102
103struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp)
104{
105 struct nf_conn_help *help;
106
107 help = nf_ct_ext_add(ct, NF_CT_EXT_HELPER, gfp);
108 if (help)
109 INIT_HLIST_HEAD(&help->expectations);
110 else
111 pr_debug("failed to add helper extension area");
112 return help;
113}
114EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
115
116int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
117 gfp_t flags)
118{
119 struct nf_conntrack_helper *helper = NULL;
120 struct nf_conn_help *help;
121 int ret = 0;
122
123 if (tmpl != NULL) {
124 help = nfct_help(tmpl);
125 if (help != NULL)
126 helper = help->helper;
127 }
128
129 help = nfct_help(ct);
130 if (helper == NULL)
131 helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
132 if (helper == NULL) {
133 if (help)
134 RCU_INIT_POINTER(help->helper, NULL);
135 goto out;
136 }
137
138 if (help == NULL) {
139 help = nf_ct_helper_ext_add(ct, flags);
140 if (help == NULL) {
141 ret = -ENOMEM;
142 goto out;
143 }
144 } else {
145 memset(&help->help, 0, sizeof(help->help));
146 }
147
148 rcu_assign_pointer(help->helper, helper);
149out:
150 return ret;
151}
152EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
153
154static inline int unhelp(struct nf_conntrack_tuple_hash *i,
155 const struct nf_conntrack_helper *me)
156{
157 struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
158 struct nf_conn_help *help = nfct_help(ct);
159
160 if (help && rcu_dereference_protected(
161 help->helper,
162 lockdep_is_held(&nf_conntrack_lock)
163 ) == me) {
164 nf_conntrack_event(IPCT_HELPER, ct);
165 RCU_INIT_POINTER(help->helper, NULL);
166 }
167 return 0;
168}
169
170void nf_ct_helper_destroy(struct nf_conn *ct)
171{
172 struct nf_conn_help *help = nfct_help(ct);
173 struct nf_conntrack_helper *helper;
174
175 if (help) {
176 rcu_read_lock();
177 helper = rcu_dereference(help->helper);
178 if (helper && helper->destroy)
179 helper->destroy(ct);
180 rcu_read_unlock();
181 }
182}
183
184int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
185{
186 unsigned int h = helper_hash(&me->tuple);
187
188 BUG_ON(me->expect_policy == NULL);
189 BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
190 BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
191
192 mutex_lock(&nf_ct_helper_mutex);
193 hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
194 nf_ct_helper_count++;
195 mutex_unlock(&nf_ct_helper_mutex);
196
197 return 0;
198}
199EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
200
201static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
202 struct net *net)
203{
204 struct nf_conntrack_tuple_hash *h;
205 struct nf_conntrack_expect *exp;
206 const struct hlist_node *n, *next;
207 const struct hlist_nulls_node *nn;
208 unsigned int i;
209
210
211 for (i = 0; i < nf_ct_expect_hsize; i++) {
212 hlist_for_each_entry_safe(exp, n, next,
213 &net->ct.expect_hash[i], hnode) {
214 struct nf_conn_help *help = nfct_help(exp->master);
215 if ((rcu_dereference_protected(
216 help->helper,
217 lockdep_is_held(&nf_conntrack_lock)
218 ) == me || exp->helper == me) &&
219 del_timer(&exp->timeout)) {
220 nf_ct_unlink_expect(exp);
221 nf_ct_expect_put(exp);
222 }
223 }
224 }
225
226
227 hlist_nulls_for_each_entry(h, nn, &net->ct.unconfirmed, hnnode)
228 unhelp(h, me);
229 for (i = 0; i < net->ct.htable_size; i++) {
230 hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode)
231 unhelp(h, me);
232 }
233}
234
235void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
236{
237 struct net *net;
238
239 mutex_lock(&nf_ct_helper_mutex);
240 hlist_del_rcu(&me->hnode);
241 nf_ct_helper_count--;
242 mutex_unlock(&nf_ct_helper_mutex);
243
244
245
246
247 synchronize_rcu();
248
249 rtnl_lock();
250 spin_lock_bh(&nf_conntrack_lock);
251 for_each_net(net)
252 __nf_conntrack_helper_unregister(me, net);
253 spin_unlock_bh(&nf_conntrack_lock);
254 rtnl_unlock();
255}
256EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
257
258static struct nf_ct_ext_type helper_extend __read_mostly = {
259 .len = sizeof(struct nf_conn_help),
260 .align = __alignof__(struct nf_conn_help),
261 .id = NF_CT_EXT_HELPER,
262};
263
264int nf_conntrack_helper_init(void)
265{
266 int err;
267
268 nf_ct_helper_hsize = 1;
269 nf_ct_helper_hash = nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
270 if (!nf_ct_helper_hash)
271 return -ENOMEM;
272
273 err = nf_ct_extend_register(&helper_extend);
274 if (err < 0)
275 goto err1;
276
277 return 0;
278
279err1:
280 nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
281 return err;
282}
283
284void nf_conntrack_helper_fini(void)
285{
286 nf_ct_extend_unregister(&helper_extend);
287 nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
288}
289
