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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(par->net, 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         rcu_read_unlock();
175         return ret;
176 
177 err_put_timeout:
178         __xt_ct_tg_timeout_put(timeout);
179 out:
180         rcu_read_unlock();
181         return ret;
182 #else
183         return -EOPNOTSUPP;
184 #endif
185 }
186 
187 static u16 xt_ct_flags_to_dir(const struct xt_ct_target_info_v1 *info)
188 {
189         switch (info->flags & (XT_CT_ZONE_DIR_ORIG |
190                                XT_CT_ZONE_DIR_REPL)) {
191         case XT_CT_ZONE_DIR_ORIG:
192                 return NF_CT_ZONE_DIR_ORIG;
193         case XT_CT_ZONE_DIR_REPL:
194                 return NF_CT_ZONE_DIR_REPL;
195         default:
196                 return NF_CT_DEFAULT_ZONE_DIR;
197         }
198 }
199 
200 static int xt_ct_tg_check(const struct xt_tgchk_param *par,
201                           struct xt_ct_target_info_v1 *info)
202 {
203         struct nf_conntrack_zone zone;
204         struct nf_conn *ct;
205         int ret = -EOPNOTSUPP;
206 
207         if (info->flags & XT_CT_NOTRACK) {
208                 ct = NULL;
209                 goto out;
210         }
211 
212 #ifndef CONFIG_NF_CONNTRACK_ZONES
213         if (info->zone || info->flags & (XT_CT_ZONE_DIR_ORIG |
214                                          XT_CT_ZONE_DIR_REPL |
215                                          XT_CT_ZONE_MARK))
216                 goto err1;
217 #endif
218 
219         ret = nf_ct_l3proto_try_module_get(par->family);
220         if (ret < 0)
221                 goto err1;
222 
223         memset(&zone, 0, sizeof(zone));
224         zone.id = info->zone;
225         zone.dir = xt_ct_flags_to_dir(info);
226         if (info->flags & XT_CT_ZONE_MARK)
227                 zone.flags |= NF_CT_FLAG_MARK;
228 
229         ct = nf_ct_tmpl_alloc(par->net, &zone, GFP_KERNEL);
230         if (!ct) {
231                 ret = -ENOMEM;
232                 goto err2;
233         }
234 
235         ret = 0;
236         if ((info->ct_events || info->exp_events) &&
237             !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
238                                   GFP_KERNEL)) {
239                 ret = -EINVAL;
240                 goto err3;
241         }
242 
243         if (info->helper[0]) {
244                 ret = xt_ct_set_helper(ct, info->helper, par);
245                 if (ret < 0)
246                         goto err3;
247         }
248 
249         if (info->timeout[0]) {
250                 ret = xt_ct_set_timeout(ct, par, info->timeout);
251                 if (ret < 0)
252                         goto err3;
253         }
254         __set_bit(IPS_CONFIRMED_BIT, &ct->status);
255         nf_conntrack_get(&ct->ct_general);
256 out:
257         info->ct = ct;
258         return 0;
259 
260 err3:
261         nf_ct_tmpl_free(ct);
262 err2:
263         nf_ct_l3proto_module_put(par->family);
264 err1:
265         return ret;
266 }
267 
268 static int xt_ct_tg_check_v0(const struct xt_tgchk_param *par)
269 {
270         struct xt_ct_target_info *info = par->targinfo;
271         struct xt_ct_target_info_v1 info_v1 = {
272                 .flags          = info->flags,
273                 .zone           = info->zone,
274                 .ct_events      = info->ct_events,
275                 .exp_events     = info->exp_events,
276         };
277         int ret;
278 
279         if (info->flags & ~XT_CT_NOTRACK)
280                 return -EINVAL;
281 
282         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
283 
284         ret = xt_ct_tg_check(par, &info_v1);
285         if (ret < 0)
286                 return ret;
287 
288         info->ct = info_v1.ct;
289 
290         return ret;
291 }
292 
293 static int xt_ct_tg_check_v1(const struct xt_tgchk_param *par)
294 {
295         struct xt_ct_target_info_v1 *info = par->targinfo;
296 
297         if (info->flags & ~XT_CT_NOTRACK)
298                 return -EINVAL;
299 
300         return xt_ct_tg_check(par, par->targinfo);
301 }
302 
303 static int xt_ct_tg_check_v2(const struct xt_tgchk_param *par)
304 {
305         struct xt_ct_target_info_v1 *info = par->targinfo;
306 
307         if (info->flags & ~XT_CT_MASK)
308                 return -EINVAL;
309 
310         return xt_ct_tg_check(par, par->targinfo);
311 }
312 
313 static void xt_ct_destroy_timeout(struct nf_conn *ct)
314 {
315 #ifdef CONFIG_NF_CONNTRACK_TIMEOUT
316         struct nf_conn_timeout *timeout_ext;
317         typeof(nf_ct_timeout_put_hook) timeout_put;
318 
319         rcu_read_lock();
320         timeout_put = rcu_dereference(nf_ct_timeout_put_hook);
321 
322         if (timeout_put) {
323                 timeout_ext = nf_ct_timeout_find(ct);
324                 if (timeout_ext) {
325                         timeout_put(timeout_ext->timeout);
326                         RCU_INIT_POINTER(timeout_ext->timeout, NULL);
327                 }
328         }
329         rcu_read_unlock();
330 #endif
331 }
332 
333 static void xt_ct_tg_destroy(const struct xt_tgdtor_param *par,
334                              struct xt_ct_target_info_v1 *info)
335 {
336         struct nf_conn *ct = info->ct;
337         struct nf_conn_help *help;
338 
339         if (ct && !nf_ct_is_untracked(ct)) {
340                 help = nfct_help(ct);
341                 if (help)
342                         module_put(help->helper->me);
343 
344                 nf_ct_l3proto_module_put(par->family);
345 
346                 xt_ct_destroy_timeout(ct);
347                 nf_ct_put(info->ct);
348         }
349 }
350 
351 static void xt_ct_tg_destroy_v0(const struct xt_tgdtor_param *par)
352 {
353         struct xt_ct_target_info *info = par->targinfo;
354         struct xt_ct_target_info_v1 info_v1 = {
355                 .flags          = info->flags,
356                 .zone           = info->zone,
357                 .ct_events      = info->ct_events,
358                 .exp_events     = info->exp_events,
359                 .ct             = info->ct,
360         };
361         memcpy(info_v1.helper, info->helper, sizeof(info->helper));
362 
363         xt_ct_tg_destroy(par, &info_v1);
364 }
365 
366 static void xt_ct_tg_destroy_v1(const struct xt_tgdtor_param *par)
367 {
368         xt_ct_tg_destroy(par, par->targinfo);
369 }
370 
371 static struct xt_target xt_ct_tg_reg[] __read_mostly = {
372         {
373                 .name           = "CT",
374                 .family         = NFPROTO_UNSPEC,
375                 .targetsize     = sizeof(struct xt_ct_target_info),
376                 .checkentry     = xt_ct_tg_check_v0,
377                 .destroy        = xt_ct_tg_destroy_v0,
378                 .target         = xt_ct_target_v0,
379                 .table          = "raw",
380                 .me             = THIS_MODULE,
381         },
382         {
383                 .name           = "CT",
384                 .family         = NFPROTO_UNSPEC,
385                 .revision       = 1,
386                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
387                 .checkentry     = xt_ct_tg_check_v1,
388                 .destroy        = xt_ct_tg_destroy_v1,
389                 .target         = xt_ct_target_v1,
390                 .table          = "raw",
391                 .me             = THIS_MODULE,
392         },
393         {
394                 .name           = "CT",
395                 .family         = NFPROTO_UNSPEC,
396                 .revision       = 2,
397                 .targetsize     = sizeof(struct xt_ct_target_info_v1),
398                 .checkentry     = xt_ct_tg_check_v2,
399                 .destroy        = xt_ct_tg_destroy_v1,
400                 .target         = xt_ct_target_v1,
401                 .table          = "raw",
402                 .me             = THIS_MODULE,
403         },
404 };
405 
406 static unsigned int
407 notrack_tg(struct sk_buff *skb, const struct xt_action_param *par)
408 {
409         /* Previously seen (loopback)? Ignore. */
410         if (skb->nfct != NULL)
411                 return XT_CONTINUE;
412 
413         skb->nfct = &nf_ct_untracked_get()->ct_general;
414         skb->nfctinfo = IP_CT_NEW;
415         nf_conntrack_get(skb->nfct);
416 
417         return XT_CONTINUE;
418 }
419 
420 static int notrack_chk(const struct xt_tgchk_param *par)
421 {
422         if (!par->net->xt.notrack_deprecated_warning) {
423                 pr_info("netfilter: NOTRACK target is deprecated, "
424                         "use CT instead or upgrade iptables\n");
425                 par->net->xt.notrack_deprecated_warning = true;
426         }
427         return 0;
428 }
429 
430 static struct xt_target notrack_tg_reg __read_mostly = {
431         .name           = "NOTRACK",
432         .revision       = 0,
433         .family         = NFPROTO_UNSPEC,
434         .checkentry     = notrack_chk,
435         .target         = notrack_tg,
436         .table          = "raw",
437         .me             = THIS_MODULE,
438 };
439 
440 static int __init xt_ct_tg_init(void)
441 {
442         int ret;
443 
444         ret = xt_register_target(&notrack_tg_reg);
445         if (ret < 0)
446                 return ret;
447 
448         ret = xt_register_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
449         if (ret < 0) {
450                 xt_unregister_target(&notrack_tg_reg);
451                 return ret;
452         }
453         return 0;
454 }
455 
456 static void __exit xt_ct_tg_exit(void)
457 {
458         xt_unregister_targets(xt_ct_tg_reg, ARRAY_SIZE(xt_ct_tg_reg));
459         xt_unregister_target(&notrack_tg_reg);
460 }
461 
462 module_init(xt_ct_tg_init);
463 module_exit(xt_ct_tg_exit);
464 
465 MODULE_LICENSE("GPL");
466 MODULE_DESCRIPTION("Xtables: connection tracking target");
467 MODULE_ALIAS("ipt_CT");
468 MODULE_ALIAS("ip6t_CT");
469 MODULE_ALIAS("ipt_NOTRACK");
470 MODULE_ALIAS("ip6t_NOTRACK");
471 

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