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