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Linux/net/netfilter/xt_CT.c

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  1 /*
  2  * Copyright (c) 2010 Patrick McHardy <kaber@trash.net>
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU General Public License version 2 as
  6  * published by the Free Software Foundation.
  7  */
  8 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  9 #include <linux/module.h>
 10 #include <linux/gfp.h>
 11 #include <linux/skbuff.h>
 12 #include <linux/netfilter_ipv4/ip_tables.h>
 13 #include <linux/netfilter_ipv6/ip6_tables.h>
 14 #include <linux/netfilter/x_tables.h>
 15 #include <linux/netfilter/xt_CT.h>
 16 #include <net/netfilter/nf_conntrack.h>
 17 #include <net/netfilter/nf_conntrack_l4proto.h>
 18 #include <net/netfilter/nf_conntrack_helper.h>
 19 #include <net/netfilter/nf_conntrack_ecache.h>
 20 #include <net/netfilter/nf_conntrack_timeout.h>
 21 #include <net/netfilter/nf_conntrack_zones.h>
 22 
 23 static inline int xt_ct_target(struct sk_buff *skb, struct nf_conn *ct)
 24 {
 25         /* Previously seen (loopback)? Ignore. */
 26         if (skb->nfct != NULL)
 27                 return XT_CONTINUE;
 28 
 29         /* special case the untracked ct : we want the percpu object */
 30         if (!ct)
 31                 ct = nf_ct_untracked_get();
 32         atomic_inc(&ct->ct_general.use);
 33         skb->nfct = &ct->ct_general;
 34         skb->nfctinfo = IP_CT_NEW;
 35 
 36         return XT_CONTINUE;
 37 }
 38 
 39 static unsigned int xt_ct_target_v0(struct sk_buff *skb,
 40                                     const struct xt_action_param *par)
 41 {
 42         const struct xt_ct_target_info *info = par->targinfo;
 43         struct nf_conn *ct = info->ct;
 44 
 45         return xt_ct_target(skb, ct);
 46 }
 47 
 48 static unsigned int xt_ct_target_v1(struct sk_buff *skb,
 49                                     const struct xt_action_param *par)
 50 {
 51         const struct xt_ct_target_info_v1 *info = par->targinfo;
 52         struct nf_conn *ct = info->ct;
 53 
 54         return xt_ct_target(skb, ct);
 55 }
 56 
 57 static u8 xt_ct_find_proto(const struct xt_tgchk_param *par)
 58 {
 59         if (par->family == NFPROTO_IPV4) {
 60                 const struct ipt_entry *e = par->entryinfo;
 61 
 62                 if (e->ip.invflags & IPT_INV_PROTO)
 63                         return 0;
 64                 return e->ip.proto;
 65         } else if (par->family == NFPROTO_IPV6) {
 66                 const struct ip6t_entry *e = par->entryinfo;
 67 
 68                 if (e->ipv6.invflags & IP6T_INV_PROTO)
 69                         return 0;
 70                 return e->ipv6.proto;
 71         } else
 72                 return 0;
 73 }
 74 
 75 static int
 76 xt_ct_set_helper(struct nf_conn *ct, const char *helper_name,
 77                  const struct xt_tgchk_param *par)
 78 {
 79         struct nf_conntrack_helper *helper;
 80         struct nf_conn_help *help;
 81         u8 proto;
 82 
 83         proto = xt_ct_find_proto(par);
 84         if (!proto) {
 85                 pr_info("You must specify a L4 protocol, and not use "
 86                         "inversions on it.\n");
 87                 return -ENOENT;
 88         }
 89 
 90         helper = nf_conntrack_helper_try_module_get(helper_name, par->family,
 91                                                     proto);
 92         if (helper == NULL) {
 93                 pr_info("No such helper \"%s\"\n", helper_name);
 94                 return -ENOENT;
 95         }
 96 
 97         help = nf_ct_helper_ext_add(ct, helper, GFP_KERNEL);
 98         if (help == NULL) {
 99                 module_put(helper->me);
100                 return -ENOMEM;
101         }
102 
103         help->helper = helper;
104         return 0;
105 }
106 
107 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
108 static void __xt_ct_tg_timeout_put(struct ctnl_timeout *timeout)
109 {
110         typeof(nf_ct_timeout_put_hook) timeout_put;
111 
112         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
113         if (timeout_put)
114                 timeout_put(timeout);
115 }
116 #endif
117 
118 static int
119 xt_ct_set_timeout(struct nf_conn *ct, const struct xt_tgchk_param *par,
120                   const char *timeout_name)
121 {
122 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
123         typeof(nf_ct_timeout_find_get_hook) timeout_find_get;
124         struct ctnl_timeout *timeout;
125         struct nf_conn_timeout *timeout_ext;
126         struct nf_conntrack_l4proto *l4proto;
127         int ret = 0;
128         u8 proto;
129 
130         rcu_read_lock();
131         timeout_find_get = rcu_dereference(nf_ct_timeout_find_get_hook);
132         if (timeout_find_get == NULL) {
133                 ret = -ENOENT;
134                 pr_info("Timeout policy base is empty\n");
135                 goto out;
136         }
137 
138         proto = xt_ct_find_proto(par);
139         if (!proto) {
140                 ret = -EINVAL;
141                 pr_info("You must specify a L4 protocol, and not use "
142                         "inversions on it.\n");
143                 goto out;
144         }
145 
146         timeout = timeout_find_get(timeout_name);
147         if (timeout == NULL) {
148                 ret = -ENOENT;
149                 pr_info("No such timeout policy \"%s\"\n", timeout_name);
150                 goto out;
151         }
152 
153         if (timeout->l3num != par->family) {
154                 ret = -EINVAL;
155                 pr_info("Timeout policy `%s' can only be used by L3 protocol "
156                         "number %d\n", timeout_name, timeout->l3num);
157                 goto err_put_timeout;
158         }
159         /* Make sure the timeout policy matches any existing protocol tracker,
160          * otherwise default to generic.
161          */
162         l4proto = __nf_ct_l4proto_find(par->family, proto);
163         if (timeout->l4proto->l4proto != l4proto->l4proto) {
164                 ret = -EINVAL;
165                 pr_info("Timeout policy `%s' can only be used by L4 protocol "
166                         "number %d\n",
167                         timeout_name, timeout->l4proto->l4proto);
168                 goto err_put_timeout;
169         }
170         timeout_ext = nf_ct_timeout_ext_add(ct, timeout, GFP_ATOMIC);
171         if (timeout_ext == NULL)
172                 ret = -ENOMEM;
173 
174 err_put_timeout:
175         __xt_ct_tg_timeout_put(timeout);
176 out:
177         rcu_read_unlock();
178         return ret;
179 #else
180         return -EOPNOTSUPP;
181 #endif
182 }
183 
184 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
185                           struct xt_ct_target_info_v1 *info)
186 {
187         struct nf_conntrack_tuple t;
188         struct nf_conn *ct;
189         int ret = -EOPNOTSUPP;
190 
191         if (info->flags & XT_CT_NOTRACK) {
192                 ct = NULL;
193                 goto out;
194         }
195 
196 #ifndef CONFIG_NF_CONNTRACK_ZONES
197         if (info->zone)
198                 goto err1;
199 #endif
200 
201         ret = nf_ct_l3proto_try_module_get(par->family);
202         if (ret < 0)
203                 goto err1;
204 
205         memset(&t, 0, sizeof(t));
206         ct = nf_conntrack_alloc(par->net, info->zone, &t, &t, GFP_KERNEL);
207         ret = PTR_ERR(ct);
208         if (IS_ERR(ct))
209                 goto err2;
210 
211         ret = 0;
212         if ((info->ct_events || info->exp_events) &&
213             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
214                                   GFP_KERNEL)) {
215                 ret = -EINVAL;
216                 goto err3;
217         }
218 
219         if (info->helper[0]) {
220                 ret = xt_ct_set_helper(ct, info->helper, par);
221                 if (ret < 0)
222                         goto err3;
223         }
224 
225         if (info->timeout[0]) {
226                 ret = xt_ct_set_timeout(ct, par, info->timeout);
227                 if (ret < 0)
228                         goto err3;
229         }
230 
231         nf_conntrack_tmpl_insert(par->net, ct);
232 out:
233         info->ct = ct;
234         return 0;
235 
236 err3:
237         nf_conntrack_free(ct);
238 err2:
239         nf_ct_l3proto_module_put(par->family);
240 err1:
241         return ret;
242 }
243 
244 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
245 {
246         struct xt_ct_target_info *info = par->targinfo;
247         struct xt_ct_target_info_v1 info_v1 = {
248                 .flags          = info->flags,
249                 .zone           = info->zone,
250                 .ct_events      = info->ct_events,
251                 .exp_events     = info->exp_events,
252         };
253         int ret;
254 
255         if (info->flags & ~XT_CT_NOTRACK)
256                 return -EINVAL;
257 
258         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
259 
260         ret = xt_ct_tg_check(par, &info_v1);
261         if (ret < 0)
262                 return ret;
263 
264         info->ct = info_v1.ct;
265 
266         return ret;
267 }
268 
269 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
270 {
271         struct xt_ct_target_info_v1 *info = par->targinfo;
272 
273         if (info->flags & ~XT_CT_NOTRACK)
274                 return -EINVAL;
275 
276         return xt_ct_tg_check(par, par->targinfo);
277 }
278 
279 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
280 {
281         struct xt_ct_target_info_v1 *info = par->targinfo;
282 
283         if (info->flags & ~XT_CT_MASK)
284                 return -EINVAL;
285 
286         return xt_ct_tg_check(par, par->targinfo);
287 }
288 
289 static void xt_ct_destroy_timeout(struct nf_conn *ct)
290 {
291 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
292         struct nf_conn_timeout *timeout_ext;
293         typeof(nf_ct_timeout_put_hook) timeout_put;
294 
295         rcu_read_lock();
296         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
297 
298         if (timeout_put) {
299                 timeout_ext = nf_ct_timeout_find(ct);
300                 if (timeout_ext)
301                         timeout_put(timeout_ext->timeout);
302         }
303         rcu_read_unlock();
304 #endif
305 }
306 
307 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
308                              struct xt_ct_target_info_v1 *info)
309 {
310         struct nf_conn *ct = info->ct;
311         struct nf_conn_help *help;
312 
313         if (ct && !nf_ct_is_untracked(ct)) {
314                 help = nfct_help(ct);
315                 if (help)
316                         module_put(help->helper->me);
317 
318                 nf_ct_l3proto_module_put(par->family);
319 
320                 xt_ct_destroy_timeout(ct);
321                 nf_ct_put(info->ct);
322         }
323 }
324 
325 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
326 {
327         struct xt_ct_target_info *info = par->targinfo;
328         struct xt_ct_target_info_v1 info_v1 = {
329                 .flags          = info->flags,
330                 .zone           = info->zone,
331                 .ct_events      = info->ct_events,
332                 .exp_events     = info->exp_events,
333                 .ct             = info->ct,
334         };
335         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
336 
337         xt_ct_tg_destroy(par, &info_v1);
338 }
339 
340 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
341 {
342         xt_ct_tg_destroy(par, par->targinfo);
343 }
344 
345 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
346         {
347                 .name           = "CT",
348                 .family         = NFPROTO_UNSPEC,
349                 .targetsize     = sizeof(struct xt_ct_target_info),
350                 .checkentry     = xt_ct_tg_check_v0,
351                 .destroy        = xt_ct_tg_destroy_v0,
352                 .target         = xt_ct_target_v0,
353                 .table          = "raw",
354                 .me             = THIS_MODULE,
355         },
356         {
357                 .name           = "CT",
358                 .family         = NFPROTO_UNSPEC,
359                 .revision       = 1,
360                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
361                 .checkentry     = xt_ct_tg_check_v1,
362                 .destroy        = xt_ct_tg_destroy_v1,
363                 .target         = xt_ct_target_v1,
364                 .table          = "raw",
365                 .me             = THIS_MODULE,
366         },
367         {
368                 .name           = "CT",
369                 .family         = NFPROTO_UNSPEC,
370                 .revision       = 2,
371                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
372                 .checkentry     = xt_ct_tg_check_v2,
373                 .destroy        = xt_ct_tg_destroy_v1,
374                 .target         = xt_ct_target_v1,
375                 .table          = "raw",
376                 .me             = THIS_MODULE,
377         },
378 };
379 
380 static unsigned int
381 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
382 {
383         /* Previously seen (loopback)? Ignore. */
384         if (skb->nfct != NULL)
385                 return XT_CONTINUE;
386 
387         skb->nfct = &nf_ct_untracked_get()->ct_general;
388         skb->nfctinfo = IP_CT_NEW;
389         nf_conntrack_get(skb->nfct);
390 
391         return XT_CONTINUE;
392 }
393 
394 static int notrack_chk(const struct xt_tgchk_param *par)
395 {
396         if (!par->net->xt.notrack_deprecated_warning) {
397                 pr_info("netfilter: NOTRACK target is deprecated, "
398                         "use CT instead or upgrade iptables\n");
399                 par->net->xt.notrack_deprecated_warning = true;
400         }
401         return 0;
402 }
403 
404 static struct xt_target notrack_tg_reg __read_mostly = {
405         .name           = "NOTRACK",
406         .revision       = 0,
407         .family         = NFPROTO_UNSPEC,
408         .checkentry     = notrack_chk,
409         .target         = notrack_tg,
410         .table          = "raw",
411         .me             = THIS_MODULE,
412 };
413 
414 static int __init xt_ct_tg_init(void)
415 {
416         int ret;
417 
418         ret = xt_register_target(&notrack_tg_reg);
419         if (ret < 0)
420                 return ret;
421 
422         ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
423         if (ret < 0) {
424                 xt_unregister_target(&notrack_tg_reg);
425                 return ret;
426         }
427         return 0;
428 }
429 
430 static void __exit xt_ct_tg_exit(void)
431 {
432         xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
433         xt_unregister_target(&notrack_tg_reg);
434 }
435 
436 module_init(xt_ct_tg_init);
437 module_exit(xt_ct_tg_exit);
438 
439 MODULE_LICENSE("GPL");
440 MODULE_DESCRIPTION("Xtables: connection tracking target");
441 MODULE_ALIAS("ipt_CT");
442 MODULE_ALIAS("ip6t_CT");
443 MODULE_ALIAS("ipt_NOTRACK");
444 MODULE_ALIAS("ip6t_NOTRACK");
445 

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