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

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  1 /*
  2  * x_tables core - Backend for {ip,ip6,arp}_tables
  3  *
  4  * Copyright (C) 2006-2006 Harald Welte <laforge@netfilter.org>
  5  * Copyright (C) 2006-2012 Patrick McHardy <kaber@trash.net>
  6  *
  7  * Based on existing ip_tables code which is
  8  *   Copyright (C) 1999 Paul `Rusty' Russell & Michael J. Neuling
  9  *   Copyright (C) 2000-2005 Netfilter Core Team <coreteam@netfilter.org>
 10  *
 11  * This program is free software; you can redistribute it and/or modify
 12  * it under the terms of the GNU General Public License version 2 as
 13  * published by the Free Software Foundation.
 14  *
 15  */
 16 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 17 #include <linux/kernel.h>
 18 #include <linux/module.h>
 19 #include <linux/socket.h>
 20 #include <linux/net.h>
 21 #include <linux/proc_fs.h>
 22 #include <linux/seq_file.h>
 23 #include <linux/string.h>
 24 #include <linux/vmalloc.h>
 25 #include <linux/mutex.h>
 26 #include <linux/mm.h>
 27 #include <linux/slab.h>
 28 #include <linux/audit.h>
 29 #include <net/net_namespace.h>
 30 
 31 #include <linux/netfilter/x_tables.h>
 32 #include <linux/netfilter_arp.h>
 33 #include <linux/netfilter_ipv4/ip_tables.h>
 34 #include <linux/netfilter_ipv6/ip6_tables.h>
 35 #include <linux/netfilter_arp/arp_tables.h>
 36 
 37 MODULE_LICENSE("GPL");
 38 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
 39 MODULE_DESCRIPTION("{ip,ip6,arp,eb}_tables backend module");
 40 
 41 #define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1))
 42 
 43 struct compat_delta {
 44         unsigned int offset; /* offset in kernel */
 45         int delta; /* delta in 32bit user land */
 46 };
 47 
 48 struct xt_af {
 49         struct mutex mutex;
 50         struct list_head match;
 51         struct list_head target;
 52 #ifdef CONFIG_COMPAT
 53         struct mutex compat_mutex;
 54         struct compat_delta *compat_tab;
 55         unsigned int number; /* number of slots in compat_tab[] */
 56         unsigned int cur; /* number of used slots in compat_tab[] */
 57 #endif
 58 };
 59 
 60 static struct xt_af *xt;
 61 
 62 static const char *const xt_prefix[NFPROTO_NUMPROTO] = {
 63         [NFPROTO_UNSPEC] = "x",
 64         [NFPROTO_IPV4]   = "ip",
 65         [NFPROTO_ARP]    = "arp",
 66         [NFPROTO_BRIDGE] = "eb",
 67         [NFPROTO_IPV6]   = "ip6",
 68 };
 69 
 70 /* Allow this many total (re)entries. */
 71 static const unsigned int xt_jumpstack_multiplier = 2;
 72 
 73 /* Registration hooks for targets. */
 74 int xt_register_target(struct xt_target *target)
 75 {
 76         u_int8_t af = target->family;
 77 
 78         mutex_lock(&xt[af].mutex);
 79         list_add(&target->list, &xt[af].target);
 80         mutex_unlock(&xt[af].mutex);
 81         return 0;
 82 }
 83 EXPORT_SYMBOL(xt_register_target);
 84 
 85 void
 86 xt_unregister_target(struct xt_target *target)
 87 {
 88         u_int8_t af = target->family;
 89 
 90         mutex_lock(&xt[af].mutex);
 91         list_del(&target->list);
 92         mutex_unlock(&xt[af].mutex);
 93 }
 94 EXPORT_SYMBOL(xt_unregister_target);
 95 
 96 int
 97 xt_register_targets(struct xt_target *target, unsigned int n)
 98 {
 99         unsigned int i;
100         int err = 0;
101 
102         for (i = 0; i < n; i++) {
103                 err = xt_register_target(&target[i]);
104                 if (err)
105                         goto err;
106         }
107         return err;
108 
109 err:
110         if (i > 0)
111                 xt_unregister_targets(target, i);
112         return err;
113 }
114 EXPORT_SYMBOL(xt_register_targets);
115 
116 void
117 xt_unregister_targets(struct xt_target *target, unsigned int n)
118 {
119         while (n-- > 0)
120                 xt_unregister_target(&target[n]);
121 }
122 EXPORT_SYMBOL(xt_unregister_targets);
123 
124 int xt_register_match(struct xt_match *match)
125 {
126         u_int8_t af = match->family;
127 
128         mutex_lock(&xt[af].mutex);
129         list_add(&match->list, &xt[af].match);
130         mutex_unlock(&xt[af].mutex);
131         return 0;
132 }
133 EXPORT_SYMBOL(xt_register_match);
134 
135 void
136 xt_unregister_match(struct xt_match *match)
137 {
138         u_int8_t af = match->family;
139 
140         mutex_lock(&xt[af].mutex);
141         list_del(&match->list);
142         mutex_unlock(&xt[af].mutex);
143 }
144 EXPORT_SYMBOL(xt_unregister_match);
145 
146 int
147 xt_register_matches(struct xt_match *match, unsigned int n)
148 {
149         unsigned int i;
150         int err = 0;
151 
152         for (i = 0; i < n; i++) {
153                 err = xt_register_match(&match[i]);
154                 if (err)
155                         goto err;
156         }
157         return err;
158 
159 err:
160         if (i > 0)
161                 xt_unregister_matches(match, i);
162         return err;
163 }
164 EXPORT_SYMBOL(xt_register_matches);
165 
166 void
167 xt_unregister_matches(struct xt_match *match, unsigned int n)
168 {
169         while (n-- > 0)
170                 xt_unregister_match(&match[n]);
171 }
172 EXPORT_SYMBOL(xt_unregister_matches);
173 
174 
175 /*
176  * These are weird, but module loading must not be done with mutex
177  * held (since they will register), and we have to have a single
178  * function to use.
179  */
180 
181 /* Find match, grabs ref.  Returns ERR_PTR() on error. */
182 struct xt_match *xt_find_match(u8 af, const char *name, u8 revision)
183 {
184         struct xt_match *m;
185         int err = -ENOENT;
186 
187         mutex_lock(&xt[af].mutex);
188         list_for_each_entry(m, &xt[af].match, list) {
189                 if (strcmp(m->name, name) == 0) {
190                         if (m->revision == revision) {
191                                 if (try_module_get(m->me)) {
192                                         mutex_unlock(&xt[af].mutex);
193                                         return m;
194                                 }
195                         } else
196                                 err = -EPROTOTYPE; /* Found something. */
197                 }
198         }
199         mutex_unlock(&xt[af].mutex);
200 
201         if (af != NFPROTO_UNSPEC)
202                 /* Try searching again in the family-independent list */
203                 return xt_find_match(NFPROTO_UNSPEC, name, revision);
204 
205         return ERR_PTR(err);
206 }
207 EXPORT_SYMBOL(xt_find_match);
208 
209 struct xt_match *
210 xt_request_find_match(uint8_t nfproto, const char *name, uint8_t revision)
211 {
212         struct xt_match *match;
213 
214         match = xt_find_match(nfproto, name, revision);
215         if (IS_ERR(match)) {
216                 request_module("%st_%s", xt_prefix[nfproto], name);
217                 match = xt_find_match(nfproto, name, revision);
218         }
219 
220         return match;
221 }
222 EXPORT_SYMBOL_GPL(xt_request_find_match);
223 
224 /* Find target, grabs ref.  Returns ERR_PTR() on error. */
225 struct xt_target *xt_find_target(u8 af, const char *name, u8 revision)
226 {
227         struct xt_target *t;
228         int err = -ENOENT;
229 
230         mutex_lock(&xt[af].mutex);
231         list_for_each_entry(t, &xt[af].target, list) {
232                 if (strcmp(t->name, name) == 0) {
233                         if (t->revision == revision) {
234                                 if (try_module_get(t->me)) {
235                                         mutex_unlock(&xt[af].mutex);
236                                         return t;
237                                 }
238                         } else
239                                 err = -EPROTOTYPE; /* Found something. */
240                 }
241         }
242         mutex_unlock(&xt[af].mutex);
243 
244         if (af != NFPROTO_UNSPEC)
245                 /* Try searching again in the family-independent list */
246                 return xt_find_target(NFPROTO_UNSPEC, name, revision);
247 
248         return ERR_PTR(err);
249 }
250 EXPORT_SYMBOL(xt_find_target);
251 
252 struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision)
253 {
254         struct xt_target *target;
255 
256         target = xt_find_target(af, name, revision);
257         if (IS_ERR(target)) {
258                 request_module("%st_%s", xt_prefix[af], name);
259                 target = xt_find_target(af, name, revision);
260         }
261 
262         return target;
263 }
264 EXPORT_SYMBOL_GPL(xt_request_find_target);
265 
266 static int match_revfn(u8 af, const char *name, u8 revision, int *bestp)
267 {
268         const struct xt_match *m;
269         int have_rev = 0;
270 
271         list_for_each_entry(m, &xt[af].match, list) {
272                 if (strcmp(m->name, name) == 0) {
273                         if (m->revision > *bestp)
274                                 *bestp = m->revision;
275                         if (m->revision == revision)
276                                 have_rev = 1;
277                 }
278         }
279 
280         if (af != NFPROTO_UNSPEC && !have_rev)
281                 return match_revfn(NFPROTO_UNSPEC, name, revision, bestp);
282 
283         return have_rev;
284 }
285 
286 static int target_revfn(u8 af, const char *name, u8 revision, int *bestp)
287 {
288         const struct xt_target *t;
289         int have_rev = 0;
290 
291         list_for_each_entry(t, &xt[af].target, list) {
292                 if (strcmp(t->name, name) == 0) {
293                         if (t->revision > *bestp)
294                                 *bestp = t->revision;
295                         if (t->revision == revision)
296                                 have_rev = 1;
297                 }
298         }
299 
300         if (af != NFPROTO_UNSPEC && !have_rev)
301                 return target_revfn(NFPROTO_UNSPEC, name, revision, bestp);
302 
303         return have_rev;
304 }
305 
306 /* Returns true or false (if no such extension at all) */
307 int xt_find_revision(u8 af, const char *name, u8 revision, int target,
308                      int *err)
309 {
310         int have_rev, best = -1;
311 
312         mutex_lock(&xt[af].mutex);
313         if (target == 1)
314                 have_rev = target_revfn(af, name, revision, &best);
315         else
316                 have_rev = match_revfn(af, name, revision, &best);
317         mutex_unlock(&xt[af].mutex);
318 
319         /* Nothing at all?  Return 0 to try loading module. */
320         if (best == -1) {
321                 *err = -ENOENT;
322                 return 0;
323         }
324 
325         *err = best;
326         if (!have_rev)
327                 *err = -EPROTONOSUPPORT;
328         return 1;
329 }
330 EXPORT_SYMBOL_GPL(xt_find_revision);
331 
332 static char *
333 textify_hooks(char *buf, size_t size, unsigned int mask, uint8_t nfproto)
334 {
335         static const char *const inetbr_names[] = {
336                 "PREROUTING", "INPUT", "FORWARD",
337                 "OUTPUT", "POSTROUTING", "BROUTING",
338         };
339         static const char *const arp_names[] = {
340                 "INPUT", "FORWARD", "OUTPUT",
341         };
342         const char *const *names;
343         unsigned int i, max;
344         char *p = buf;
345         bool np = false;
346         int res;
347 
348         names = (nfproto == NFPROTO_ARP) ? arp_names : inetbr_names;
349         max   = (nfproto == NFPROTO_ARP) ? ARRAY_SIZE(arp_names) :
350                                            ARRAY_SIZE(inetbr_names);
351         *p = '\0';
352         for (i = 0; i < max; ++i) {
353                 if (!(mask & (1 << i)))
354                         continue;
355                 res = snprintf(p, size, "%s%s", np ? "/" : "", names[i]);
356                 if (res > 0) {
357                         size -= res;
358                         p += res;
359                 }
360                 np = true;
361         }
362 
363         return buf;
364 }
365 
366 int xt_check_match(struct xt_mtchk_param *par,
367                    unsigned int size, u_int8_t proto, bool inv_proto)
368 {
369         int ret;
370 
371         if (XT_ALIGN(par->match->matchsize) != size &&
372             par->match->matchsize != -1) {
373                 /*
374                  * ebt_among is exempt from centralized matchsize checking
375                  * because it uses a dynamic-size data set.
376                  */
377                 pr_err("%s_tables: %s.%u match: invalid size "
378                        "%u (kernel) != (user) %u\n",
379                        xt_prefix[par->family], par->match->name,
380                        par->match->revision,
381                        XT_ALIGN(par->match->matchsize), size);
382                 return -EINVAL;
383         }
384         if (par->match->table != NULL &&
385             strcmp(par->match->table, par->table) != 0) {
386                 pr_err("%s_tables: %s match: only valid in %s table, not %s\n",
387                        xt_prefix[par->family], par->match->name,
388                        par->match->table, par->table);
389                 return -EINVAL;
390         }
391         if (par->match->hooks && (par->hook_mask & ~par->match->hooks) != 0) {
392                 char used[64], allow[64];
393 
394                 pr_err("%s_tables: %s match: used from hooks %s, but only "
395                        "valid from %s\n",
396                        xt_prefix[par->family], par->match->name,
397                        textify_hooks(used, sizeof(used), par->hook_mask,
398                                      par->family),
399                        textify_hooks(allow, sizeof(allow), par->match->hooks,
400                                      par->family));
401                 return -EINVAL;
402         }
403         if (par->match->proto && (par->match->proto != proto || inv_proto)) {
404                 pr_err("%s_tables: %s match: only valid for protocol %u\n",
405                        xt_prefix[par->family], par->match->name,
406                        par->match->proto);
407                 return -EINVAL;
408         }
409         if (par->match->checkentry != NULL) {
410                 ret = par->match->checkentry(par);
411                 if (ret < 0)
412                         return ret;
413                 else if (ret > 0)
414                         /* Flag up potential errors. */
415                         return -EIO;
416         }
417         return 0;
418 }
419 EXPORT_SYMBOL_GPL(xt_check_match);
420 
421 #ifdef CONFIG_COMPAT
422 int xt_compat_add_offset(u_int8_t af, unsigned int offset, int delta)
423 {
424         struct xt_af *xp = &xt[af];
425 
426         if (!xp->compat_tab) {
427                 if (!xp->number)
428                         return -EINVAL;
429                 xp->compat_tab = vmalloc(sizeof(struct compat_delta) * xp->number);
430                 if (!xp->compat_tab)
431                         return -ENOMEM;
432                 xp->cur = 0;
433         }
434 
435         if (xp->cur >= xp->number)
436                 return -EINVAL;
437 
438         if (xp->cur)
439                 delta += xp->compat_tab[xp->cur - 1].delta;
440         xp->compat_tab[xp->cur].offset = offset;
441         xp->compat_tab[xp->cur].delta = delta;
442         xp->cur++;
443         return 0;
444 }
445 EXPORT_SYMBOL_GPL(xt_compat_add_offset);
446 
447 void xt_compat_flush_offsets(u_int8_t af)
448 {
449         if (xt[af].compat_tab) {
450                 vfree(xt[af].compat_tab);
451                 xt[af].compat_tab = NULL;
452                 xt[af].number = 0;
453                 xt[af].cur = 0;
454         }
455 }
456 EXPORT_SYMBOL_GPL(xt_compat_flush_offsets);
457 
458 int xt_compat_calc_jump(u_int8_t af, unsigned int offset)
459 {
460         struct compat_delta *tmp = xt[af].compat_tab;
461         int mid, left = 0, right = xt[af].cur - 1;
462 
463         while (left <= right) {
464                 mid = (left + right) >> 1;
465                 if (offset > tmp[mid].offset)
466                         left = mid + 1;
467                 else if (offset < tmp[mid].offset)
468                         right = mid - 1;
469                 else
470                         return mid ? tmp[mid - 1].delta : 0;
471         }
472         return left ? tmp[left - 1].delta : 0;
473 }
474 EXPORT_SYMBOL_GPL(xt_compat_calc_jump);
475 
476 void xt_compat_init_offsets(u_int8_t af, unsigned int number)
477 {
478         xt[af].number = number;
479         xt[af].cur = 0;
480 }
481 EXPORT_SYMBOL(xt_compat_init_offsets);
482 
483 int xt_compat_match_offset(const struct xt_match *match)
484 {
485         u_int16_t csize = match->compatsize ? : match->matchsize;
486         return XT_ALIGN(match->matchsize) - COMPAT_XT_ALIGN(csize);
487 }
488 EXPORT_SYMBOL_GPL(xt_compat_match_offset);
489 
490 int xt_compat_match_from_user(struct xt_entry_match *m, void **dstptr,
491                               unsigned int *size)
492 {
493         const struct xt_match *match = m->u.kernel.match;
494         struct compat_xt_entry_match *cm = (struct compat_xt_entry_match *)m;
495         int pad, off = xt_compat_match_offset(match);
496         u_int16_t msize = cm->u.user.match_size;
497 
498         m = *dstptr;
499         memcpy(m, cm, sizeof(*cm));
500         if (match->compat_from_user)
501                 match->compat_from_user(m->data, cm->data);
502         else
503                 memcpy(m->data, cm->data, msize - sizeof(*cm));
504         pad = XT_ALIGN(match->matchsize) - match->matchsize;
505         if (pad > 0)
506                 memset(m->data + match->matchsize, 0, pad);
507 
508         msize += off;
509         m->u.user.match_size = msize;
510 
511         *size += off;
512         *dstptr += msize;
513         return 0;
514 }
515 EXPORT_SYMBOL_GPL(xt_compat_match_from_user);
516 
517 int xt_compat_match_to_user(const struct xt_entry_match *m,
518                             void __user **dstptr, unsigned int *size)
519 {
520         const struct xt_match *match = m->u.kernel.match;
521         struct compat_xt_entry_match __user *cm = *dstptr;
522         int off = xt_compat_match_offset(match);
523         u_int16_t msize = m->u.user.match_size - off;
524 
525         if (copy_to_user(cm, m, sizeof(*cm)) ||
526             put_user(msize, &cm->u.user.match_size) ||
527             copy_to_user(cm->u.user.name, m->u.kernel.match->name,
528                          strlen(m->u.kernel.match->name) + 1))
529                 return -EFAULT;
530 
531         if (match->compat_to_user) {
532                 if (match->compat_to_user((void __user *)cm->data, m->data))
533                         return -EFAULT;
534         } else {
535                 if (copy_to_user(cm->data, m->data, msize - sizeof(*cm)))
536                         return -EFAULT;
537         }
538 
539         *size -= off;
540         *dstptr += msize;
541         return 0;
542 }
543 EXPORT_SYMBOL_GPL(xt_compat_match_to_user);
544 #endif /* CONFIG_COMPAT */
545 
546 int xt_check_target(struct xt_tgchk_param *par,
547                     unsigned int size, u_int8_t proto, bool inv_proto)
548 {
549         int ret;
550 
551         if (XT_ALIGN(par->target->targetsize) != size) {
552                 pr_err("%s_tables: %s.%u target: invalid size "
553                        "%u (kernel) != (user) %u\n",
554                        xt_prefix[par->family], par->target->name,
555                        par->target->revision,
556                        XT_ALIGN(par->target->targetsize), size);
557                 return -EINVAL;
558         }
559         if (par->target->table != NULL &&
560             strcmp(par->target->table, par->table) != 0) {
561                 pr_err("%s_tables: %s target: only valid in %s table, not %s\n",
562                        xt_prefix[par->family], par->target->name,
563                        par->target->table, par->table);
564                 return -EINVAL;
565         }
566         if (par->target->hooks && (par->hook_mask & ~par->target->hooks) != 0) {
567                 char used[64], allow[64];
568 
569                 pr_err("%s_tables: %s target: used from hooks %s, but only "
570                        "usable from %s\n",
571                        xt_prefix[par->family], par->target->name,
572                        textify_hooks(used, sizeof(used), par->hook_mask,
573                                      par->family),
574                        textify_hooks(allow, sizeof(allow), par->target->hooks,
575                                      par->family));
576                 return -EINVAL;
577         }
578         if (par->target->proto && (par->target->proto != proto || inv_proto)) {
579                 pr_err("%s_tables: %s target: only valid for protocol %u\n",
580                        xt_prefix[par->family], par->target->name,
581                        par->target->proto);
582                 return -EINVAL;
583         }
584         if (par->target->checkentry != NULL) {
585                 ret = par->target->checkentry(par);
586                 if (ret < 0)
587                         return ret;
588                 else if (ret > 0)
589                         /* Flag up potential errors. */
590                         return -EIO;
591         }
592         return 0;
593 }
594 EXPORT_SYMBOL_GPL(xt_check_target);
595 
596 #ifdef CONFIG_COMPAT
597 int xt_compat_target_offset(const struct xt_target *target)
598 {
599         u_int16_t csize = target->compatsize ? : target->targetsize;
600         return XT_ALIGN(target->targetsize) - COMPAT_XT_ALIGN(csize);
601 }
602 EXPORT_SYMBOL_GPL(xt_compat_target_offset);
603 
604 void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,
605                                 unsigned int *size)
606 {
607         const struct xt_target *target = t->u.kernel.target;
608         struct compat_xt_entry_target *ct = (struct compat_xt_entry_target *)t;
609         int pad, off = xt_compat_target_offset(target);
610         u_int16_t tsize = ct->u.user.target_size;
611 
612         t = *dstptr;
613         memcpy(t, ct, sizeof(*ct));
614         if (target->compat_from_user)
615                 target->compat_from_user(t->data, ct->data);
616         else
617                 memcpy(t->data, ct->data, tsize - sizeof(*ct));
618         pad = XT_ALIGN(target->targetsize) - target->targetsize;
619         if (pad > 0)
620                 memset(t->data + target->targetsize, 0, pad);
621 
622         tsize += off;
623         t->u.user.target_size = tsize;
624 
625         *size += off;
626         *dstptr += tsize;
627 }
628 EXPORT_SYMBOL_GPL(xt_compat_target_from_user);
629 
630 int xt_compat_target_to_user(const struct xt_entry_target *t,
631                              void __user **dstptr, unsigned int *size)
632 {
633         const struct xt_target *target = t->u.kernel.target;
634         struct compat_xt_entry_target __user *ct = *dstptr;
635         int off = xt_compat_target_offset(target);
636         u_int16_t tsize = t->u.user.target_size - off;
637 
638         if (copy_to_user(ct, t, sizeof(*ct)) ||
639             put_user(tsize, &ct->u.user.target_size) ||
640             copy_to_user(ct->u.user.name, t->u.kernel.target->name,
641                          strlen(t->u.kernel.target->name) + 1))
642                 return -EFAULT;
643 
644         if (target->compat_to_user) {
645                 if (target->compat_to_user((void __user *)ct->data, t->data))
646                         return -EFAULT;
647         } else {
648                 if (copy_to_user(ct->data, t->data, tsize - sizeof(*ct)))
649                         return -EFAULT;
650         }
651 
652         *size -= off;
653         *dstptr += tsize;
654         return 0;
655 }
656 EXPORT_SYMBOL_GPL(xt_compat_target_to_user);
657 #endif
658 
659 struct xt_table_info *xt_alloc_table_info(unsigned int size)
660 {
661         struct xt_table_info *newinfo;
662         int cpu;
663 
664         /* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
665         if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > totalram_pages)
666                 return NULL;
667 
668         newinfo = kzalloc(XT_TABLE_INFO_SZ, GFP_KERNEL);
669         if (!newinfo)
670                 return NULL;
671 
672         newinfo->size = size;
673 
674         for_each_possible_cpu(cpu) {
675                 if (size <= PAGE_SIZE)
676                         newinfo->entries[cpu] = kmalloc_node(size,
677                                                         GFP_KERNEL,
678                                                         cpu_to_node(cpu));
679                 else
680                         newinfo->entries[cpu] = vmalloc_node(size,
681                                                         cpu_to_node(cpu));
682 
683                 if (newinfo->entries[cpu] == NULL) {
684                         xt_free_table_info(newinfo);
685                         return NULL;
686                 }
687         }
688 
689         return newinfo;
690 }
691 EXPORT_SYMBOL(xt_alloc_table_info);
692 
693 void xt_free_table_info(struct xt_table_info *info)
694 {
695         int cpu;
696 
697         for_each_possible_cpu(cpu)
698                 kvfree(info->entries[cpu]);
699 
700         if (info->jumpstack != NULL) {
701                 for_each_possible_cpu(cpu)
702                         kvfree(info->jumpstack[cpu]);
703                 kvfree(info->jumpstack);
704         }
705 
706         free_percpu(info->stackptr);
707 
708         kfree(info);
709 }
710 EXPORT_SYMBOL(xt_free_table_info);
711 
712 /* Find table by name, grabs mutex & ref.  Returns ERR_PTR() on error. */
713 struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
714                                     const char *name)
715 {
716         struct xt_table *t;
717 
718         mutex_lock(&xt[af].mutex);
719         list_for_each_entry(t, &net->xt.tables[af], list)
720                 if (strcmp(t->name, name) == 0 && try_module_get(t->me))
721                         return t;
722         mutex_unlock(&xt[af].mutex);
723         return NULL;
724 }
725 EXPORT_SYMBOL_GPL(xt_find_table_lock);
726 
727 void xt_table_unlock(struct xt_table *table)
728 {
729         mutex_unlock(&xt[table->af].mutex);
730 }
731 EXPORT_SYMBOL_GPL(xt_table_unlock);
732 
733 #ifdef CONFIG_COMPAT
734 void xt_compat_lock(u_int8_t af)
735 {
736         mutex_lock(&xt[af].compat_mutex);
737 }
738 EXPORT_SYMBOL_GPL(xt_compat_lock);
739 
740 void xt_compat_unlock(u_int8_t af)
741 {
742         mutex_unlock(&xt[af].compat_mutex);
743 }
744 EXPORT_SYMBOL_GPL(xt_compat_unlock);
745 #endif
746 
747 DEFINE_PER_CPU(seqcount_t, xt_recseq);
748 EXPORT_PER_CPU_SYMBOL_GPL(xt_recseq);
749 
750 static int xt_jumpstack_alloc(struct xt_table_info *i)
751 {
752         unsigned int size;
753         int cpu;
754 
755         i->stackptr = alloc_percpu(unsigned int);
756         if (i->stackptr == NULL)
757                 return -ENOMEM;
758 
759         size = sizeof(void **) * nr_cpu_ids;
760         if (size > PAGE_SIZE)
761                 i->jumpstack = vzalloc(size);
762         else
763                 i->jumpstack = kzalloc(size, GFP_KERNEL);
764         if (i->jumpstack == NULL)
765                 return -ENOMEM;
766 
767         i->stacksize *= xt_jumpstack_multiplier;
768         size = sizeof(void *) * i->stacksize;
769         for_each_possible_cpu(cpu) {
770                 if (size > PAGE_SIZE)
771                         i->jumpstack[cpu] = vmalloc_node(size,
772                                 cpu_to_node(cpu));
773                 else
774                         i->jumpstack[cpu] = kmalloc_node(size,
775                                 GFP_KERNEL, cpu_to_node(cpu));
776                 if (i->jumpstack[cpu] == NULL)
777                         /*
778                          * Freeing will be done later on by the callers. The
779                          * chain is: xt_replace_table -> __do_replace ->
780                          * do_replace -> xt_free_table_info.
781                          */
782                         return -ENOMEM;
783         }
784 
785         return 0;
786 }
787 
788 struct xt_table_info *
789 xt_replace_table(struct xt_table *table,
790               unsigned int num_counters,
791               struct xt_table_info *newinfo,
792               int *error)
793 {
794         struct xt_table_info *private;
795         int ret;
796 
797         ret = xt_jumpstack_alloc(newinfo);
798         if (ret < 0) {
799                 *error = ret;
800                 return NULL;
801         }
802 
803         /* Do the substitution. */
804         local_bh_disable();
805         private = table->private;
806 
807         /* Check inside lock: is the old number correct? */
808         if (num_counters != private->number) {
809                 pr_debug("num_counters != table->private->number (%u/%u)\n",
810                          num_counters, private->number);
811                 local_bh_enable();
812                 *error = -EAGAIN;
813                 return NULL;
814         }
815 
816         newinfo->initial_entries = private->initial_entries;
817         /*
818          * Ensure contents of newinfo are visible before assigning to
819          * private.
820          */
821         smp_wmb();
822         table->private = newinfo;
823 
824         /*
825          * Even though table entries have now been swapped, other CPU's
826          * may still be using the old entries. This is okay, because
827          * resynchronization happens because of the locking done
828          * during the get_counters() routine.
829          */
830         local_bh_enable();
831 
832 #ifdef CONFIG_AUDIT
833         if (audit_enabled) {
834                 struct audit_buffer *ab;
835 
836                 ab = audit_log_start(current->audit_context, GFP_KERNEL,
837                                      AUDIT_NETFILTER_CFG);
838                 if (ab) {
839                         audit_log_format(ab, "table=%s family=%u entries=%u",
840                                          table->name, table->af,
841                                          private->number);
842                         audit_log_end(ab);
843                 }
844         }
845 #endif
846 
847         return private;
848 }
849 EXPORT_SYMBOL_GPL(xt_replace_table);
850 
851 struct xt_table *xt_register_table(struct net *net,
852                                    const struct xt_table *input_table,
853                                    struct xt_table_info *bootstrap,
854                                    struct xt_table_info *newinfo)
855 {
856         int ret;
857         struct xt_table_info *private;
858         struct xt_table *t, *table;
859 
860         /* Don't add one object to multiple lists. */
861         table = kmemdup(input_table, sizeof(struct xt_table), GFP_KERNEL);
862         if (!table) {
863                 ret = -ENOMEM;
864                 goto out;
865         }
866 
867         mutex_lock(&xt[table->af].mutex);
868         /* Don't autoload: we'd eat our tail... */
869         list_for_each_entry(t, &net->xt.tables[table->af], list) {
870                 if (strcmp(t->name, table->name) == 0) {
871                         ret = -EEXIST;
872                         goto unlock;
873                 }
874         }
875 
876         /* Simplifies replace_table code. */
877         table->private = bootstrap;
878 
879         if (!xt_replace_table(table, 0, newinfo, &ret))
880                 goto unlock;
881 
882         private = table->private;
883         pr_debug("table->private->number = %u\n", private->number);
884 
885         /* save number of initial entries */
886         private->initial_entries = private->number;
887 
888         list_add(&table->list, &net->xt.tables[table->af]);
889         mutex_unlock(&xt[table->af].mutex);
890         return table;
891 
892 unlock:
893         mutex_unlock(&xt[table->af].mutex);
894         kfree(table);
895 out:
896         return ERR_PTR(ret);
897 }
898 EXPORT_SYMBOL_GPL(xt_register_table);
899 
900 void *xt_unregister_table(struct xt_table *table)
901 {
902         struct xt_table_info *private;
903 
904         mutex_lock(&xt[table->af].mutex);
905         private = table->private;
906         list_del(&table->list);
907         mutex_unlock(&xt[table->af].mutex);
908         kfree(table);
909 
910         return private;
911 }
912 EXPORT_SYMBOL_GPL(xt_unregister_table);
913 
914 #ifdef CONFIG_PROC_FS
915 struct xt_names_priv {
916         struct seq_net_private p;
917         u_int8_t af;
918 };
919 static void *xt_table_seq_start(struct seq_file *seq, loff_t *pos)
920 {
921         struct xt_names_priv *priv = seq->private;
922         struct net *net = seq_file_net(seq);
923         u_int8_t af = priv->af;
924 
925         mutex_lock(&xt[af].mutex);
926         return seq_list_start(&net->xt.tables[af], *pos);
927 }
928 
929 static void *xt_table_seq_next(struct seq_file *seq, void *v, loff_t *pos)
930 {
931         struct xt_names_priv *priv = seq->private;
932         struct net *net = seq_file_net(seq);
933         u_int8_t af = priv->af;
934 
935         return seq_list_next(v, &net->xt.tables[af], pos);
936 }
937 
938 static void xt_table_seq_stop(struct seq_file *seq, void *v)
939 {
940         struct xt_names_priv *priv = seq->private;
941         u_int8_t af = priv->af;
942 
943         mutex_unlock(&xt[af].mutex);
944 }
945 
946 static int xt_table_seq_show(struct seq_file *seq, void *v)
947 {
948         struct xt_table *table = list_entry(v, struct xt_table, list);
949 
950         if (strlen(table->name))
951                 return seq_printf(seq, "%s\n", table->name);
952         else
953                 return 0;
954 }
955 
956 static const struct seq_operations xt_table_seq_ops = {
957         .start  = xt_table_seq_start,
958         .next   = xt_table_seq_next,
959         .stop   = xt_table_seq_stop,
960         .show   = xt_table_seq_show,
961 };
962 
963 static int xt_table_open(struct inode *inode, struct file *file)
964 {
965         int ret;
966         struct xt_names_priv *priv;
967 
968         ret = seq_open_net(inode, file, &xt_table_seq_ops,
969                            sizeof(struct xt_names_priv));
970         if (!ret) {
971                 priv = ((struct seq_file *)file->private_data)->private;
972                 priv->af = (unsigned long)PDE_DATA(inode);
973         }
974         return ret;
975 }
976 
977 static const struct file_operations xt_table_ops = {
978         .owner   = THIS_MODULE,
979         .open    = xt_table_open,
980         .read    = seq_read,
981         .llseek  = seq_lseek,
982         .release = seq_release_net,
983 };
984 
985 /*
986  * Traverse state for ip{,6}_{tables,matches} for helping crossing
987  * the multi-AF mutexes.
988  */
989 struct nf_mttg_trav {
990         struct list_head *head, *curr;
991         uint8_t class, nfproto;
992 };
993 
994 enum {
995         MTTG_TRAV_INIT,
996         MTTG_TRAV_NFP_UNSPEC,
997         MTTG_TRAV_NFP_SPEC,
998         MTTG_TRAV_DONE,
999 };
1000 
1001 static void *xt_mttg_seq_next(struct seq_file *seq, void *v, loff_t *ppos,
1002     bool is_target)
1003 {
1004         static const uint8_t next_class[] = {
1005                 [MTTG_TRAV_NFP_UNSPEC] = MTTG_TRAV_NFP_SPEC,
1006                 [MTTG_TRAV_NFP_SPEC]   = MTTG_TRAV_DONE,
1007         };
1008         struct nf_mttg_trav *trav = seq->private;
1009 
1010         switch (trav->class) {
1011         case MTTG_TRAV_INIT:
1012                 trav->class = MTTG_TRAV_NFP_UNSPEC;
1013                 mutex_lock(&xt[NFPROTO_UNSPEC].mutex);
1014                 trav->head = trav->curr = is_target ?
1015                         &xt[NFPROTO_UNSPEC].target : &xt[NFPROTO_UNSPEC].match;
1016                 break;
1017         case MTTG_TRAV_NFP_UNSPEC:
1018                 trav->curr = trav->curr->next;
1019                 if (trav->curr != trav->head)
1020                         break;
1021                 mutex_unlock(&xt[NFPROTO_UNSPEC].mutex);
1022                 mutex_lock(&xt[trav->nfproto].mutex);
1023                 trav->head = trav->curr = is_target ?
1024                         &xt[trav->nfproto].target : &xt[trav->nfproto].match;
1025                 trav->class = next_class[trav->class];
1026                 break;
1027         case MTTG_TRAV_NFP_SPEC:
1028                 trav->curr = trav->curr->next;
1029                 if (trav->curr != trav->head)
1030                         break;
1031                 /* fallthru, _stop will unlock */
1032         default:
1033                 return NULL;
1034         }
1035 
1036         if (ppos != NULL)
1037                 ++*ppos;
1038         return trav;
1039 }
1040 
1041 static void *xt_mttg_seq_start(struct seq_file *seq, loff_t *pos,
1042     bool is_target)
1043 {
1044         struct nf_mttg_trav *trav = seq->private;
1045         unsigned int j;
1046 
1047         trav->class = MTTG_TRAV_INIT;
1048         for (j = 0; j < *pos; ++j)
1049                 if (xt_mttg_seq_next(seq, NULL, NULL, is_target) == NULL)
1050                         return NULL;
1051         return trav;
1052 }
1053 
1054 static void xt_mttg_seq_stop(struct seq_file *seq, void *v)
1055 {
1056         struct nf_mttg_trav *trav = seq->private;
1057 
1058         switch (trav->class) {
1059         case MTTG_TRAV_NFP_UNSPEC:
1060                 mutex_unlock(&xt[NFPROTO_UNSPEC].mutex);
1061                 break;
1062         case MTTG_TRAV_NFP_SPEC:
1063                 mutex_unlock(&xt[trav->nfproto].mutex);
1064                 break;
1065         }
1066 }
1067 
1068 static void *xt_match_seq_start(struct seq_file *seq, loff_t *pos)
1069 {
1070         return xt_mttg_seq_start(seq, pos, false);
1071 }
1072 
1073 static void *xt_match_seq_next(struct seq_file *seq, void *v, loff_t *ppos)
1074 {
1075         return xt_mttg_seq_next(seq, v, ppos, false);
1076 }
1077 
1078 static int xt_match_seq_show(struct seq_file *seq, void *v)
1079 {
1080         const struct nf_mttg_trav *trav = seq->private;
1081         const struct xt_match *match;
1082 
1083         switch (trav->class) {
1084         case MTTG_TRAV_NFP_UNSPEC:
1085         case MTTG_TRAV_NFP_SPEC:
1086                 if (trav->curr == trav->head)
1087                         return 0;
1088                 match = list_entry(trav->curr, struct xt_match, list);
1089                 return (*match->name == '\0') ? 0 :
1090                        seq_printf(seq, "%s\n", match->name);
1091         }
1092         return 0;
1093 }
1094 
1095 static const struct seq_operations xt_match_seq_ops = {
1096         .start  = xt_match_seq_start,
1097         .next   = xt_match_seq_next,
1098         .stop   = xt_mttg_seq_stop,
1099         .show   = xt_match_seq_show,
1100 };
1101 
1102 static int xt_match_open(struct inode *inode, struct file *file)
1103 {
1104         struct seq_file *seq;
1105         struct nf_mttg_trav *trav;
1106         int ret;
1107 
1108         trav = kmalloc(sizeof(*trav), GFP_KERNEL);
1109         if (trav == NULL)
1110                 return -ENOMEM;
1111 
1112         ret = seq_open(file, &xt_match_seq_ops);
1113         if (ret < 0) {
1114                 kfree(trav);
1115                 return ret;
1116         }
1117 
1118         seq = file->private_data;
1119         seq->private = trav;
1120         trav->nfproto = (unsigned long)PDE_DATA(inode);
1121         return 0;
1122 }
1123 
1124 static const struct file_operations xt_match_ops = {
1125         .owner   = THIS_MODULE,
1126         .open    = xt_match_open,
1127         .read    = seq_read,
1128         .llseek  = seq_lseek,
1129         .release = seq_release_private,
1130 };
1131 
1132 static void *xt_target_seq_start(struct seq_file *seq, loff_t *pos)
1133 {
1134         return xt_mttg_seq_start(seq, pos, true);
1135 }
1136 
1137 static void *xt_target_seq_next(struct seq_file *seq, void *v, loff_t *ppos)
1138 {
1139         return xt_mttg_seq_next(seq, v, ppos, true);
1140 }
1141 
1142 static int xt_target_seq_show(struct seq_file *seq, void *v)
1143 {
1144         const struct nf_mttg_trav *trav = seq->private;
1145         const struct xt_target *target;
1146 
1147         switch (trav->class) {
1148         case MTTG_TRAV_NFP_UNSPEC:
1149         case MTTG_TRAV_NFP_SPEC:
1150                 if (trav->curr == trav->head)
1151                         return 0;
1152                 target = list_entry(trav->curr, struct xt_target, list);
1153                 return (*target->name == '\0') ? 0 :
1154                        seq_printf(seq, "%s\n", target->name);
1155         }
1156         return 0;
1157 }
1158 
1159 static const struct seq_operations xt_target_seq_ops = {
1160         .start  = xt_target_seq_start,
1161         .next   = xt_target_seq_next,
1162         .stop   = xt_mttg_seq_stop,
1163         .show   = xt_target_seq_show,
1164 };
1165 
1166 static int xt_target_open(struct inode *inode, struct file *file)
1167 {
1168         struct seq_file *seq;
1169         struct nf_mttg_trav *trav;
1170         int ret;
1171 
1172         trav = kmalloc(sizeof(*trav), GFP_KERNEL);
1173         if (trav == NULL)
1174                 return -ENOMEM;
1175 
1176         ret = seq_open(file, &xt_target_seq_ops);
1177         if (ret < 0) {
1178                 kfree(trav);
1179                 return ret;
1180         }
1181 
1182         seq = file->private_data;
1183         seq->private = trav;
1184         trav->nfproto = (unsigned long)PDE_DATA(inode);
1185         return 0;
1186 }
1187 
1188 static const struct file_operations xt_target_ops = {
1189         .owner   = THIS_MODULE,
1190         .open    = xt_target_open,
1191         .read    = seq_read,
1192         .llseek  = seq_lseek,
1193         .release = seq_release_private,
1194 };
1195 
1196 #define FORMAT_TABLES   "_tables_names"
1197 #define FORMAT_MATCHES  "_tables_matches"
1198 #define FORMAT_TARGETS  "_tables_targets"
1199 
1200 #endif /* CONFIG_PROC_FS */
1201 
1202 /**
1203  * xt_hook_link - set up hooks for a new table
1204  * @table:      table with metadata needed to set up hooks
1205  * @fn:         Hook function
1206  *
1207  * This function will take care of creating and registering the necessary
1208  * Netfilter hooks for XT tables.
1209  */
1210 struct nf_hook_ops *xt_hook_link(const struct xt_table *table, nf_hookfn *fn)
1211 {
1212         unsigned int hook_mask = table->valid_hooks;
1213         uint8_t i, num_hooks = hweight32(hook_mask);
1214         uint8_t hooknum;
1215         struct nf_hook_ops *ops;
1216         int ret;
1217 
1218         ops = kmalloc(sizeof(*ops) * num_hooks, GFP_KERNEL);
1219         if (ops == NULL)
1220                 return ERR_PTR(-ENOMEM);
1221 
1222         for (i = 0, hooknum = 0; i < num_hooks && hook_mask != 0;
1223              hook_mask >>= 1, ++hooknum) {
1224                 if (!(hook_mask & 1))
1225                         continue;
1226                 ops[i].hook     = fn;
1227                 ops[i].owner    = table->me;
1228                 ops[i].pf       = table->af;
1229                 ops[i].hooknum  = hooknum;
1230                 ops[i].priority = table->priority;
1231                 ++i;
1232         }
1233 
1234         ret = nf_register_hooks(ops, num_hooks);
1235         if (ret < 0) {
1236                 kfree(ops);
1237                 return ERR_PTR(ret);
1238         }
1239 
1240         return ops;
1241 }
1242 EXPORT_SYMBOL_GPL(xt_hook_link);
1243 
1244 /**
1245  * xt_hook_unlink - remove hooks for a table
1246  * @ops:        nf_hook_ops array as returned by nf_hook_link
1247  * @hook_mask:  the very same mask that was passed to nf_hook_link
1248  */
1249 void xt_hook_unlink(const struct xt_table *table, struct nf_hook_ops *ops)
1250 {
1251         nf_unregister_hooks(ops, hweight32(table->valid_hooks));
1252         kfree(ops);
1253 }
1254 EXPORT_SYMBOL_GPL(xt_hook_unlink);
1255 
1256 int xt_proto_init(struct net *net, u_int8_t af)
1257 {
1258 #ifdef CONFIG_PROC_FS
1259         char buf[XT_FUNCTION_MAXNAMELEN];
1260         struct proc_dir_entry *proc;
1261 #endif
1262 
1263         if (af >= ARRAY_SIZE(xt_prefix))
1264                 return -EINVAL;
1265 
1266 
1267 #ifdef CONFIG_PROC_FS
1268         strlcpy(buf, xt_prefix[af], sizeof(buf));
1269         strlcat(buf, FORMAT_TABLES, sizeof(buf));
1270         proc = proc_create_data(buf, 0440, net->proc_net, &xt_table_ops,
1271                                 (void *)(unsigned long)af);
1272         if (!proc)
1273                 goto out;
1274 
1275         strlcpy(buf, xt_prefix[af], sizeof(buf));
1276         strlcat(buf, FORMAT_MATCHES, sizeof(buf));
1277         proc = proc_create_data(buf, 0440, net->proc_net, &xt_match_ops,
1278                                 (void *)(unsigned long)af);
1279         if (!proc)
1280                 goto out_remove_tables;
1281 
1282         strlcpy(buf, xt_prefix[af], sizeof(buf));
1283         strlcat(buf, FORMAT_TARGETS, sizeof(buf));
1284         proc = proc_create_data(buf, 0440, net->proc_net, &xt_target_ops,
1285                                 (void *)(unsigned long)af);
1286         if (!proc)
1287                 goto out_remove_matches;
1288 #endif
1289 
1290         return 0;
1291 
1292 #ifdef CONFIG_PROC_FS
1293 out_remove_matches:
1294         strlcpy(buf, xt_prefix[af], sizeof(buf));
1295         strlcat(buf, FORMAT_MATCHES, sizeof(buf));
1296         remove_proc_entry(buf, net->proc_net);
1297 
1298 out_remove_tables:
1299         strlcpy(buf, xt_prefix[af], sizeof(buf));
1300         strlcat(buf, FORMAT_TABLES, sizeof(buf));
1301         remove_proc_entry(buf, net->proc_net);
1302 out:
1303         return -1;
1304 #endif
1305 }
1306 EXPORT_SYMBOL_GPL(xt_proto_init);
1307 
1308 void xt_proto_fini(struct net *net, u_int8_t af)
1309 {
1310 #ifdef CONFIG_PROC_FS
1311         char buf[XT_FUNCTION_MAXNAMELEN];
1312 
1313         strlcpy(buf, xt_prefix[af], sizeof(buf));
1314         strlcat(buf, FORMAT_TABLES, sizeof(buf));
1315         remove_proc_entry(buf, net->proc_net);
1316 
1317         strlcpy(buf, xt_prefix[af], sizeof(buf));
1318         strlcat(buf, FORMAT_TARGETS, sizeof(buf));
1319         remove_proc_entry(buf, net->proc_net);
1320 
1321         strlcpy(buf, xt_prefix[af], sizeof(buf));
1322         strlcat(buf, FORMAT_MATCHES, sizeof(buf));
1323         remove_proc_entry(buf, net->proc_net);
1324 #endif /*CONFIG_PROC_FS*/
1325 }
1326 EXPORT_SYMBOL_GPL(xt_proto_fini);
1327 
1328 static int __net_init xt_net_init(struct net *net)
1329 {
1330         int i;
1331 
1332         for (i = 0; i < NFPROTO_NUMPROTO; i++)
1333                 INIT_LIST_HEAD(&net->xt.tables[i]);
1334         return 0;
1335 }
1336 
1337 static struct pernet_operations xt_net_ops = {
1338         .init = xt_net_init,
1339 };
1340 
1341 static int __init xt_init(void)
1342 {
1343         unsigned int i;
1344         int rv;
1345 
1346         for_each_possible_cpu(i) {
1347                 seqcount_init(&per_cpu(xt_recseq, i));
1348         }
1349 
1350         xt = kmalloc(sizeof(struct xt_af) * NFPROTO_NUMPROTO, GFP_KERNEL);
1351         if (!xt)
1352                 return -ENOMEM;
1353 
1354         for (i = 0; i < NFPROTO_NUMPROTO; i++) {
1355                 mutex_init(&xt[i].mutex);
1356 #ifdef CONFIG_COMPAT
1357                 mutex_init(&xt[i].compat_mutex);
1358                 xt[i].compat_tab = NULL;
1359 #endif
1360                 INIT_LIST_HEAD(&xt[i].target);
1361                 INIT_LIST_HEAD(&xt[i].match);
1362         }
1363         rv = register_pernet_subsys(&xt_net_ops);
1364         if (rv < 0)
1365                 kfree(xt);
1366         return rv;
1367 }
1368 
1369 static void __exit xt_fini(void)
1370 {
1371         unregister_pernet_subsys(&xt_net_ops);
1372         kfree(xt);
1373 }
1374 
1375 module_init(xt_init);
1376 module_exit(xt_fini);
1377 
1378 

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