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

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