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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 u16 xt_ct_flags_to_dir(const struct xt_ct_target_info_v1 *info)
185 {
186         switch (info->flags & (XT_CT_ZONE_DIR_ORIG |
187                                XT_CT_ZONE_DIR_REPL)) {
188         case XT_CT_ZONE_DIR_ORIG:
189                 return NF_CT_ZONE_DIR_ORIG;
190         case XT_CT_ZONE_DIR_REPL:
191                 return NF_CT_ZONE_DIR_REPL;
192         default:
193                 return NF_CT_DEFAULT_ZONE_DIR;
194         }
195 }
196 
197 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
198                           struct xt_ct_target_info_v1 *info)
199 {
200         struct nf_conntrack_zone zone;
201         struct nf_conn *ct;
202         int ret = -EOPNOTSUPP;
203 
204         if (info->flags & XT_CT_NOTRACK) {
205                 ct = NULL;
206                 goto out;
207         }
208 
209 #ifndef CONFIG_NF_CONNTRACK_ZONES
210         if (info->zone || info->flags & (XT_CT_ZONE_DIR_ORIG |
211                                          XT_CT_ZONE_DIR_REPL |
212                                          XT_CT_ZONE_MARK))
213                 goto err1;
214 #endif
215 
216         ret = nf_ct_l3proto_try_module_get(par->family);
217         if (ret < 0)
218                 goto err1;
219 
220         memset(&zone, 0, sizeof(zone));
221         zone.id = info->zone;
222         zone.dir = xt_ct_flags_to_dir(info);
223         if (info->flags & XT_CT_ZONE_MARK)
224                 zone.flags |= NF_CT_FLAG_MARK;
225 
226         ct = nf_ct_tmpl_alloc(par->net, &zone, GFP_KERNEL);
227         if (!ct) {
228                 ret = -ENOMEM;
229                 goto err2;
230         }
231 
232         ret = 0;
233         if ((info->ct_events || info->exp_events) &&
234             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
235                                   GFP_KERNEL)) {
236                 ret = -EINVAL;
237                 goto err3;
238         }
239 
240         if (info->helper[0]) {
241                 ret = xt_ct_set_helper(ct, info->helper, par);
242                 if (ret < 0)
243                         goto err3;
244         }
245 
246         if (info->timeout[0]) {
247                 ret = xt_ct_set_timeout(ct, par, info->timeout);
248                 if (ret < 0)
249                         goto err3;
250         }
251         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
252         nf_conntrack_get(&ct->ct_general);
253 out:
254         info->ct = ct;
255         return 0;
256 
257 err3:
258         nf_ct_tmpl_free(ct);
259 err2:
260         nf_ct_l3proto_module_put(par->family);
261 err1:
262         return ret;
263 }
264 
265 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
266 {
267         struct xt_ct_target_info *info = par->targinfo;
268         struct xt_ct_target_info_v1 info_v1 = {
269                 .flags          = info->flags,
270                 .zone           = info->zone,
271                 .ct_events      = info->ct_events,
272                 .exp_events     = info->exp_events,
273         };
274         int ret;
275 
276         if (info->flags & ~XT_CT_NOTRACK)
277                 return -EINVAL;
278 
279         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
280 
281         ret = xt_ct_tg_check(par, &info_v1);
282         if (ret < 0)
283                 return ret;
284 
285         info->ct = info_v1.ct;
286 
287         return ret;
288 }
289 
290 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
291 {
292         struct xt_ct_target_info_v1 *info = par->targinfo;
293 
294         if (info->flags & ~XT_CT_NOTRACK)
295                 return -EINVAL;
296 
297         return xt_ct_tg_check(par, par->targinfo);
298 }
299 
300 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
301 {
302         struct xt_ct_target_info_v1 *info = par->targinfo;
303 
304         if (info->flags & ~XT_CT_MASK)
305                 return -EINVAL;
306 
307         return xt_ct_tg_check(par, par->targinfo);
308 }
309 
310 static void xt_ct_destroy_timeout(struct nf_conn *ct)
311 {
312 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
313         struct nf_conn_timeout *timeout_ext;
314         typeof(nf_ct_timeout_put_hook) timeout_put;
315 
316         rcu_read_lock();
317         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
318 
319         if (timeout_put) {
320                 timeout_ext = nf_ct_timeout_find(ct);
321                 if (timeout_ext)
322                         timeout_put(timeout_ext->timeout);
323         }
324         rcu_read_unlock();
325 #endif
326 }
327 
328 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
329                              struct xt_ct_target_info_v1 *info)
330 {
331         struct nf_conn *ct = info->ct;
332         struct nf_conn_help *help;
333 
334         if (ct && !nf_ct_is_untracked(ct)) {
335                 help = nfct_help(ct);
336                 if (help)
337                         module_put(help->helper->me);
338 
339                 nf_ct_l3proto_module_put(par->family);
340 
341                 xt_ct_destroy_timeout(ct);
342                 nf_ct_put(info->ct);
343         }
344 }
345 
346 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
347 {
348         struct xt_ct_target_info *info = par->targinfo;
349         struct xt_ct_target_info_v1 info_v1 = {
350                 .flags          = info->flags,
351                 .zone           = info->zone,
352                 .ct_events      = info->ct_events,
353                 .exp_events     = info->exp_events,
354                 .ct             = info->ct,
355         };
356         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
357 
358         xt_ct_tg_destroy(par, &info_v1);
359 }
360 
361 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
362 {
363         xt_ct_tg_destroy(par, par->targinfo);
364 }
365 
366 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
367         {
368                 .name           = "CT",
369                 .family         = NFPROTO_UNSPEC,
370                 .targetsize     = sizeof(struct xt_ct_target_info),
371                 .checkentry     = xt_ct_tg_check_v0,
372                 .destroy        = xt_ct_tg_destroy_v0,
373                 .target         = xt_ct_target_v0,
374                 .table          = "raw",
375                 .me             = THIS_MODULE,
376         },
377         {
378                 .name           = "CT",
379                 .family         = NFPROTO_UNSPEC,
380                 .revision       = 1,
381                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
382                 .checkentry     = xt_ct_tg_check_v1,
383                 .destroy        = xt_ct_tg_destroy_v1,
384                 .target         = xt_ct_target_v1,
385                 .table          = "raw",
386                 .me             = THIS_MODULE,
387         },
388         {
389                 .name           = "CT",
390                 .family         = NFPROTO_UNSPEC,
391                 .revision       = 2,
392                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
393                 .checkentry     = xt_ct_tg_check_v2,
394                 .destroy        = xt_ct_tg_destroy_v1,
395                 .target         = xt_ct_target_v1,
396                 .table          = "raw",
397                 .me             = THIS_MODULE,
398         },
399 };
400 
401 static unsigned int
402 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
403 {
404         /* Previously seen (loopback)? Ignore. */
405         if (skb->nfct != NULL)
406                 return XT_CONTINUE;
407 
408         skb->nfct = &nf_ct_untracked_get()->ct_general;
409         skb->nfctinfo = IP_CT_NEW;
410         nf_conntrack_get(skb->nfct);
411 
412         return XT_CONTINUE;
413 }
414 
415 static int notrack_chk(const struct xt_tgchk_param *par)
416 {
417         if (!par->net->xt.notrack_deprecated_warning) {
418                 pr_info("netfilter: NOTRACK target is deprecated, "
419                         "use CT instead or upgrade iptables\n");
420                 par->net->xt.notrack_deprecated_warning = true;
421         }
422         return 0;
423 }
424 
425 static struct xt_target notrack_tg_reg __read_mostly = {
426         .name           = "NOTRACK",
427         .revision       = 0,
428         .family         = NFPROTO_UNSPEC,
429         .checkentry     = notrack_chk,
430         .target         = notrack_tg,
431         .table          = "raw",
432         .me             = THIS_MODULE,
433 };
434 
435 static int __init xt_ct_tg_init(void)
436 {
437         int ret;
438 
439         ret = xt_register_target(&notrack_tg_reg);
440         if (ret < 0)
441                 return ret;
442 
443         ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
444         if (ret < 0) {
445                 xt_unregister_target(&notrack_tg_reg);
446                 return ret;
447         }
448         return 0;
449 }
450 
451 static void __exit xt_ct_tg_exit(void)
452 {
453         xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
454         xt_unregister_target(&notrack_tg_reg);
455 }
456 
457 module_init(xt_ct_tg_init);
458 module_exit(xt_ct_tg_exit);
459 
460 MODULE_LICENSE("GPL");
461 MODULE_DESCRIPTION("Xtables: connection tracking target");
462 MODULE_ALIAS("ipt_CT");
463 MODULE_ALIAS("ip6t_CT");
464 MODULE_ALIAS("ipt_NOTRACK");
465 MODULE_ALIAS("ip6t_NOTRACK");
466 

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