~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

TOMOYO Linux Cross Reference
Linux/net/netfilter/nf_conntrack_helper.c

Version: ~ [ linux-5.4-rc3 ] ~ [ linux-5.3.6 ] ~ [ linux-5.2.21 ] ~ [ linux-5.1.21 ] ~ [ linux-5.0.21 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.79 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.149 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.196 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.196 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.140 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.75 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
Architecture: ~ [ i386 ] ~ [ alpha ] ~ [ m68k ] ~ [ mips ] ~ [ ppc ] ~ [ sparc ] ~ [ sparc64 ] ~

  1 /* Helper handling for netfilter. */
  2 
  3 /* (C) 1999-2001 Paul `Rusty' Russell
  4  * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org>
  5  * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
  6  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
  7  *
  8  * This program is free software; you can redistribute it and/or modify
  9  * it under the terms of the GNU General Public License version 2 as
 10  * published by the Free Software Foundation.
 11  */
 12 
 13 #include <linux/types.h>
 14 #include <linux/netfilter.h>
 15 #include <linux/module.h>
 16 #include <linux/skbuff.h>
 17 #include <linux/vmalloc.h>
 18 #include <linux/stddef.h>
 19 #include <linux/random.h>
 20 #include <linux/err.h>
 21 #include <linux/kernel.h>
 22 #include <linux/netdevice.h>
 23 #include <linux/rculist.h>
 24 #include <linux/rtnetlink.h>
 25 
 26 #include <net/netfilter/nf_conntrack.h>
 27 #include <net/netfilter/nf_conntrack_l3proto.h>
 28 #include <net/netfilter/nf_conntrack_l4proto.h>
 29 #include <net/netfilter/nf_conntrack_helper.h>
 30 #include <net/netfilter/nf_conntrack_core.h>
 31 #include <net/netfilter/nf_conntrack_extend.h>
 32 #include <net/netfilter/nf_log.h>
 33 
 34 static DEFINE_MUTEX(nf_ct_helper_mutex);
 35 struct hlist_head *nf_ct_helper_hash __read_mostly;
 36 EXPORT_SYMBOL_GPL(nf_ct_helper_hash);
 37 unsigned int nf_ct_helper_hsize __read_mostly;
 38 EXPORT_SYMBOL_GPL(nf_ct_helper_hsize);
 39 static unsigned int nf_ct_helper_count __read_mostly;
 40 
 41 static bool nf_ct_auto_assign_helper __read_mostly = true;
 42 module_param_named(nf_conntrack_helper, nf_ct_auto_assign_helper, bool, 0644);
 43 MODULE_PARM_DESC(nf_conntrack_helper,
 44                  "Enable automatic conntrack helper assignment (default 1)");
 45 
 46 #ifdef CONFIG_SYSCTL
 47 static struct ctl_table helper_sysctl_table[] = {
 48         {
 49                 .procname       = "nf_conntrack_helper",
 50                 .data           = &init_net.ct.sysctl_auto_assign_helper,
 51                 .maxlen         = sizeof(unsigned int),
 52                 .mode           = 0644,
 53                 .proc_handler   = proc_dointvec,
 54         },
 55         {}
 56 };
 57 
 58 static int nf_conntrack_helper_init_sysctl(struct net *net)
 59 {
 60         struct ctl_table *table;
 61 
 62         table = kmemdup(helper_sysctl_table, sizeof(helper_sysctl_table),
 63                         GFP_KERNEL);
 64         if (!table)
 65                 goto out;
 66 
 67         table[0].data = &net->ct.sysctl_auto_assign_helper;
 68 
 69         /* Don't export sysctls to unprivileged users */
 70         if (net->user_ns != &init_user_ns)
 71                 table[0].procname = NULL;
 72 
 73         net->ct.helper_sysctl_header =
 74                 register_net_sysctl(net, "net/netfilter", table);
 75 
 76         if (!net->ct.helper_sysctl_header) {
 77                 pr_err("nf_conntrack_helper: can't register to sysctl.\n");
 78                 goto out_register;
 79         }
 80         return 0;
 81 
 82 out_register:
 83         kfree(table);
 84 out:
 85         return -ENOMEM;
 86 }
 87 
 88 static void nf_conntrack_helper_fini_sysctl(struct net *net)
 89 {
 90         struct ctl_table *table;
 91 
 92         table = net->ct.helper_sysctl_header->ctl_table_arg;
 93         unregister_net_sysctl_table(net->ct.helper_sysctl_header);
 94         kfree(table);
 95 }
 96 #else
 97 static int nf_conntrack_helper_init_sysctl(struct net *net)
 98 {
 99         return 0;
100 }
101 
102 static void nf_conntrack_helper_fini_sysctl(struct net *net)
103 {
104 }
105 #endif /* CONFIG_SYSCTL */
106 
107 /* Stupid hash, but collision free for the default registrations of the
108  * helpers currently in the kernel. */
109 static unsigned int helper_hash(const struct nf_conntrack_tuple *tuple)
110 {
111         return (((tuple->src.l3num << 8) | tuple->dst.protonum) ^
112                 (__force __u16)tuple->src.u.all) % nf_ct_helper_hsize;
113 }
114 
115 static struct nf_conntrack_helper *
116 __nf_ct_helper_find(const struct nf_conntrack_tuple *tuple)
117 {
118         struct nf_conntrack_helper *helper;
119         struct nf_conntrack_tuple_mask mask = { .src.u.all = htons(0xFFFF) };
120         unsigned int h;
121 
122         if (!nf_ct_helper_count)
123                 return NULL;
124 
125         h = helper_hash(tuple);
126         hlist_for_each_entry_rcu(helper, &nf_ct_helper_hash[h], hnode) {
127                 if (nf_ct_tuple_src_mask_cmp(tuple, &helper->tuple, &mask))
128                         return helper;
129         }
130         return NULL;
131 }
132 
133 struct nf_conntrack_helper *
134 __nf_conntrack_helper_find(const char *name, u16 l3num, u8 protonum)
135 {
136         struct nf_conntrack_helper *h;
137         unsigned int i;
138 
139         for (i = 0; i < nf_ct_helper_hsize; i++) {
140                 hlist_for_each_entry_rcu(h, &nf_ct_helper_hash[i], hnode) {
141                         if (!strcmp(h->name, name) &&
142                             h->tuple.src.l3num == l3num &&
143                             h->tuple.dst.protonum == protonum)
144                                 return h;
145                 }
146         }
147         return NULL;
148 }
149 EXPORT_SYMBOL_GPL(__nf_conntrack_helper_find);
150 
151 struct nf_conntrack_helper *
152 nf_conntrack_helper_try_module_get(const char *name, u16 l3num, u8 protonum)
153 {
154         struct nf_conntrack_helper *h;
155 
156         h = __nf_conntrack_helper_find(name, l3num, protonum);
157 #ifdef CONFIG_MODULES
158         if (h == NULL) {
159                 if (request_module("nfct-helper-%s", name) == 0)
160                         h = __nf_conntrack_helper_find(name, l3num, protonum);
161         }
162 #endif
163         if (h != NULL && !try_module_get(h->me))
164                 h = NULL;
165 
166         return h;
167 }
168 EXPORT_SYMBOL_GPL(nf_conntrack_helper_try_module_get);
169 
170 struct nf_conn_help *
171 nf_ct_helper_ext_add(struct nf_conn *ct,
172                      struct nf_conntrack_helper *helper, gfp_t gfp)
173 {
174         struct nf_conn_help *help;
175 
176         help = nf_ct_ext_add_length(ct, NF_CT_EXT_HELPER,
177                                     helper->data_len, gfp);
178         if (help)
179                 INIT_HLIST_HEAD(&help->expectations);
180         else
181                 pr_debug("failed to add helper extension area");
182         return help;
183 }
184 EXPORT_SYMBOL_GPL(nf_ct_helper_ext_add);
185 
186 int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
187                               gfp_t flags)
188 {
189         struct nf_conntrack_helper *helper = NULL;
190         struct nf_conn_help *help;
191         struct net *net = nf_ct_net(ct);
192         int ret = 0;
193 
194         /* We already got a helper explicitly attached. The function
195          * nf_conntrack_alter_reply - in case NAT is in use - asks for looking
196          * the helper up again. Since now the user is in full control of
197          * making consistent helper configurations, skip this automatic
198          * re-lookup, otherwise we'll lose the helper.
199          */
200         if (test_bit(IPS_HELPER_BIT, &ct->status))
201                 return 0;
202 
203         if (tmpl != NULL) {
204                 help = nfct_help(tmpl);
205                 if (help != NULL) {
206                         helper = help->helper;
207                         set_bit(IPS_HELPER_BIT, &ct->status);
208                 }
209         }
210 
211         help = nfct_help(ct);
212         if (net->ct.sysctl_auto_assign_helper && helper == NULL) {
213                 helper = __nf_ct_helper_find(&ct->tuplehash[IP_CT_DIR_REPLY].tuple);
214                 if (unlikely(!net->ct.auto_assign_helper_warned && helper)) {
215                         pr_info("nf_conntrack: automatic helper "
216                                 "assignment is deprecated and it will "
217                                 "be removed soon. Use the iptables CT target "
218                                 "to attach helpers instead.\n");
219                         net->ct.auto_assign_helper_warned = true;
220                 }
221         }
222 
223         if (helper == NULL) {
224                 if (help)
225                         RCU_INIT_POINTER(help->helper, NULL);
226                 goto out;
227         }
228 
229         if (help == NULL) {
230                 help = nf_ct_helper_ext_add(ct, helper, flags);
231                 if (help == NULL) {
232                         ret = -ENOMEM;
233                         goto out;
234                 }
235         } else {
236                 /* We only allow helper re-assignment of the same sort since
237                  * we cannot reallocate the helper extension area.
238                  */
239                 struct nf_conntrack_helper *tmp = rcu_dereference(help->helper);
240 
241                 if (tmp && tmp->help != helper->help) {
242                         RCU_INIT_POINTER(help->helper, NULL);
243                         goto out;
244                 }
245         }
246 
247         rcu_assign_pointer(help->helper, helper);
248 out:
249         return ret;
250 }
251 EXPORT_SYMBOL_GPL(__nf_ct_try_assign_helper);
252 
253 /* appropriate ct lock protecting must be taken by caller */
254 static inline int unhelp(struct nf_conntrack_tuple_hash *i,
255                          const struct nf_conntrack_helper *me)
256 {
257         struct nf_conn *ct = nf_ct_tuplehash_to_ctrack(i);
258         struct nf_conn_help *help = nfct_help(ct);
259 
260         if (help && rcu_dereference_raw(help->helper) == me) {
261                 nf_conntrack_event(IPCT_HELPER, ct);
262                 RCU_INIT_POINTER(help->helper, NULL);
263         }
264         return 0;
265 }
266 
267 void nf_ct_helper_destroy(struct nf_conn *ct)
268 {
269         struct nf_conn_help *help = nfct_help(ct);
270         struct nf_conntrack_helper *helper;
271 
272         if (help) {
273                 rcu_read_lock();
274                 helper = rcu_dereference(help->helper);
275                 if (helper && helper->destroy)
276                         helper->destroy(ct);
277                 rcu_read_unlock();
278         }
279 }
280 
281 static LIST_HEAD(nf_ct_helper_expectfn_list);
282 
283 void nf_ct_helper_expectfn_register(struct nf_ct_helper_expectfn *n)
284 {
285         spin_lock_bh(&nf_conntrack_expect_lock);
286         list_add_rcu(&n->head, &nf_ct_helper_expectfn_list);
287         spin_unlock_bh(&nf_conntrack_expect_lock);
288 }
289 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_register);
290 
291 void nf_ct_helper_expectfn_unregister(struct nf_ct_helper_expectfn *n)
292 {
293         spin_lock_bh(&nf_conntrack_expect_lock);
294         list_del_rcu(&n->head);
295         spin_unlock_bh(&nf_conntrack_expect_lock);
296 }
297 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_unregister);
298 
299 struct nf_ct_helper_expectfn *
300 nf_ct_helper_expectfn_find_by_name(const char *name)
301 {
302         struct nf_ct_helper_expectfn *cur;
303         bool found = false;
304 
305         rcu_read_lock();
306         list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
307                 if (!strcmp(cur->name, name)) {
308                         found = true;
309                         break;
310                 }
311         }
312         rcu_read_unlock();
313         return found ? cur : NULL;
314 }
315 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_name);
316 
317 struct nf_ct_helper_expectfn *
318 nf_ct_helper_expectfn_find_by_symbol(const void *symbol)
319 {
320         struct nf_ct_helper_expectfn *cur;
321         bool found = false;
322 
323         rcu_read_lock();
324         list_for_each_entry_rcu(cur, &nf_ct_helper_expectfn_list, head) {
325                 if (cur->expectfn == symbol) {
326                         found = true;
327                         break;
328                 }
329         }
330         rcu_read_unlock();
331         return found ? cur : NULL;
332 }
333 EXPORT_SYMBOL_GPL(nf_ct_helper_expectfn_find_by_symbol);
334 
335 __printf(3, 4)
336 void nf_ct_helper_log(struct sk_buff *skb, const struct nf_conn *ct,
337                       const char *fmt, ...)
338 {
339         const struct nf_conn_help *help;
340         const struct nf_conntrack_helper *helper;
341         struct va_format vaf;
342         va_list args;
343 
344         va_start(args, fmt);
345 
346         vaf.fmt = fmt;
347         vaf.va = &args;
348 
349         /* Called from the helper function, this call never fails */
350         help = nfct_help(ct);
351 
352         /* rcu_read_lock()ed by nf_hook_slow */
353         helper = rcu_dereference(help->helper);
354 
355         nf_log_packet(nf_ct_net(ct), nf_ct_l3num(ct), 0, skb, NULL, NULL, NULL,
356                       "nf_ct_%s: dropping packet: %pV ", helper->name, &vaf);
357 
358         va_end(args);
359 }
360 EXPORT_SYMBOL_GPL(nf_ct_helper_log);
361 
362 int nf_conntrack_helper_register(struct nf_conntrack_helper *me)
363 {
364         int ret = 0;
365         struct nf_conntrack_helper *cur;
366         unsigned int h = helper_hash(&me->tuple);
367 
368         BUG_ON(me->expect_policy == NULL);
369         BUG_ON(me->expect_class_max >= NF_CT_MAX_EXPECT_CLASSES);
370         BUG_ON(strlen(me->name) > NF_CT_HELPER_NAME_LEN - 1);
371 
372         mutex_lock(&nf_ct_helper_mutex);
373         hlist_for_each_entry(cur, &nf_ct_helper_hash[h], hnode) {
374                 if (strncmp(cur->name, me->name, NF_CT_HELPER_NAME_LEN) == 0 &&
375                     cur->tuple.src.l3num == me->tuple.src.l3num &&
376                     cur->tuple.dst.protonum == me->tuple.dst.protonum) {
377                         ret = -EEXIST;
378                         goto out;
379                 }
380         }
381         hlist_add_head_rcu(&me->hnode, &nf_ct_helper_hash[h]);
382         nf_ct_helper_count++;
383 out:
384         mutex_unlock(&nf_ct_helper_mutex);
385         return ret;
386 }
387 EXPORT_SYMBOL_GPL(nf_conntrack_helper_register);
388 
389 static void __nf_conntrack_helper_unregister(struct nf_conntrack_helper *me,
390                                              struct net *net)
391 {
392         struct nf_conntrack_tuple_hash *h;
393         struct nf_conntrack_expect *exp;
394         const struct hlist_node *next;
395         const struct hlist_nulls_node *nn;
396         unsigned int i;
397         int cpu;
398 
399         /* Get rid of expectations */
400         spin_lock_bh(&nf_conntrack_expect_lock);
401         for (i = 0; i < nf_ct_expect_hsize; i++) {
402                 hlist_for_each_entry_safe(exp, next,
403                                           &net->ct.expect_hash[i], hnode) {
404                         struct nf_conn_help *help = nfct_help(exp->master);
405                         if ((rcu_dereference_protected(
406                                         help->helper,
407                                         lockdep_is_held(&nf_conntrack_expect_lock)
408                                         ) == me || exp->helper == me) &&
409                             del_timer(&exp->timeout)) {
410                                 nf_ct_unlink_expect(exp);
411                                 nf_ct_expect_put(exp);
412                         }
413                 }
414         }
415         spin_unlock_bh(&nf_conntrack_expect_lock);
416 
417         /* Get rid of expecteds, set helpers to NULL. */
418         for_each_possible_cpu(cpu) {
419                 struct ct_pcpu *pcpu = per_cpu_ptr(net->ct.pcpu_lists, cpu);
420 
421                 spin_lock_bh(&pcpu->lock);
422                 hlist_nulls_for_each_entry(h, nn, &pcpu->unconfirmed, hnnode)
423                         unhelp(h, me);
424                 spin_unlock_bh(&pcpu->lock);
425         }
426         local_bh_disable();
427         for (i = 0; i < net->ct.htable_size; i++) {
428                 spin_lock(&nf_conntrack_locks[i % CONNTRACK_LOCKS]);
429                 if (i < net->ct.htable_size) {
430                         hlist_nulls_for_each_entry(h, nn, &net->ct.hash[i], hnnode)
431                                 unhelp(h, me);
432                 }
433                 spin_unlock(&nf_conntrack_locks[i % CONNTRACK_LOCKS]);
434         }
435         local_bh_enable();
436 }
437 
438 void nf_conntrack_helper_unregister(struct nf_conntrack_helper *me)
439 {
440         struct net *net;
441 
442         mutex_lock(&nf_ct_helper_mutex);
443         hlist_del_rcu(&me->hnode);
444         nf_ct_helper_count--;
445         mutex_unlock(&nf_ct_helper_mutex);
446 
447         /* Make sure every nothing is still using the helper unless its a
448          * connection in the hash.
449          */
450         synchronize_rcu();
451 
452         rtnl_lock();
453         for_each_net(net)
454                 __nf_conntrack_helper_unregister(me, net);
455         rtnl_unlock();
456 }
457 EXPORT_SYMBOL_GPL(nf_conntrack_helper_unregister);
458 
459 static struct nf_ct_ext_type helper_extend __read_mostly = {
460         .len    = sizeof(struct nf_conn_help),
461         .align  = __alignof__(struct nf_conn_help),
462         .id     = NF_CT_EXT_HELPER,
463 };
464 
465 int nf_conntrack_helper_pernet_init(struct net *net)
466 {
467         net->ct.auto_assign_helper_warned = false;
468         net->ct.sysctl_auto_assign_helper = nf_ct_auto_assign_helper;
469         return nf_conntrack_helper_init_sysctl(net);
470 }
471 
472 void nf_conntrack_helper_pernet_fini(struct net *net)
473 {
474         nf_conntrack_helper_fini_sysctl(net);
475 }
476 
477 int nf_conntrack_helper_init(void)
478 {
479         int ret;
480         nf_ct_helper_hsize = 1; /* gets rounded up to use one page */
481         nf_ct_helper_hash =
482                 nf_ct_alloc_hashtable(&nf_ct_helper_hsize, 0);
483         if (!nf_ct_helper_hash)
484                 return -ENOMEM;
485 
486         ret = nf_ct_extend_register(&helper_extend);
487         if (ret < 0) {
488                 pr_err("nf_ct_helper: Unable to register helper extension.\n");
489                 goto out_extend;
490         }
491 
492         return 0;
493 out_extend:
494         nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
495         return ret;
496 }
497 
498 void nf_conntrack_helper_fini(void)
499 {
500         nf_ct_extend_unregister(&helper_extend);
501         nf_ct_free_hashtable(nf_ct_helper_hash, nf_ct_helper_hsize);
502 }
503 

~ [ source navigation ] ~ [ diff markup ] ~ [ identifier search ] ~

kernel.org | git.kernel.org | LWN.net | Project Home | Wiki (Japanese) | Wiki (English) | SVN repository | Mail admin

Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.

osdn.jp