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 /* Registration hooks for targets. */
xt_register_target(struct xt_target * target)71 int xt_register_target(struct xt_target *target)
72 {
73 	u_int8_t af = target->family;
74 
75 	mutex_lock(&xt[af].mutex);
76 	list_add(&target->list, &xt[af].target);
77 	mutex_unlock(&xt[af].mutex);
78 	return 0;
79 }
80 EXPORT_SYMBOL(xt_register_target);
81 
82 void
xt_unregister_target(struct xt_target * target)83 xt_unregister_target(struct xt_target *target)
84 {
85 	u_int8_t af = target->family;
86 
87 	mutex_lock(&xt[af].mutex);
88 	list_del(&target->list);
89 	mutex_unlock(&xt[af].mutex);
90 }
91 EXPORT_SYMBOL(xt_unregister_target);
92 
93 int
xt_register_targets(struct xt_target * target,unsigned int n)94 xt_register_targets(struct xt_target *target, unsigned int n)
95 {
96 	unsigned int i;
97 	int err = 0;
98 
99 	for (i = 0; i < n; i++) {
100 		err = xt_register_target(&target[i]);
101 		if (err)
102 			goto err;
103 	}
104 	return err;
105 
106 err:
107 	if (i > 0)
108 		xt_unregister_targets(target, i);
109 	return err;
110 }
111 EXPORT_SYMBOL(xt_register_targets);
112 
113 void
xt_unregister_targets(struct xt_target * target,unsigned int n)114 xt_unregister_targets(struct xt_target *target, unsigned int n)
115 {
116 	while (n-- > 0)
117 		xt_unregister_target(&target[n]);
118 }
119 EXPORT_SYMBOL(xt_unregister_targets);
120 
xt_register_match(struct xt_match * match)121 int xt_register_match(struct xt_match *match)
122 {
123 	u_int8_t af = match->family;
124 
125 	mutex_lock(&xt[af].mutex);
126 	list_add(&match->list, &xt[af].match);
127 	mutex_unlock(&xt[af].mutex);
128 	return 0;
129 }
130 EXPORT_SYMBOL(xt_register_match);
131 
132 void
xt_unregister_match(struct xt_match * match)133 xt_unregister_match(struct xt_match *match)
134 {
135 	u_int8_t af = match->family;
136 
137 	mutex_lock(&xt[af].mutex);
138 	list_del(&match->list);
139 	mutex_unlock(&xt[af].mutex);
140 }
141 EXPORT_SYMBOL(xt_unregister_match);
142 
143 int
xt_register_matches(struct xt_match * match,unsigned int n)144 xt_register_matches(struct xt_match *match, unsigned int n)
145 {
146 	unsigned int i;
147 	int err = 0;
148 
149 	for (i = 0; i < n; i++) {
150 		err = xt_register_match(&match[i]);
151 		if (err)
152 			goto err;
153 	}
154 	return err;
155 
156 err:
157 	if (i > 0)
158 		xt_unregister_matches(match, i);
159 	return err;
160 }
161 EXPORT_SYMBOL(xt_register_matches);
162 
163 void
xt_unregister_matches(struct xt_match * match,unsigned int n)164 xt_unregister_matches(struct xt_match *match, unsigned int n)
165 {
166 	while (n-- > 0)
167 		xt_unregister_match(&match[n]);
168 }
169 EXPORT_SYMBOL(xt_unregister_matches);
170 
171 
172 /*
173  * These are weird, but module loading must not be done with mutex
174  * held (since they will register), and we have to have a single
175  * function to use.
176  */
177 
178 /* Find match, grabs ref.  Returns ERR_PTR() on error. */
xt_find_match(u8 af,const char * name,u8 revision)179 struct xt_match *xt_find_match(u8 af, const char *name, u8 revision)
180 {
181 	struct xt_match *m;
182 	int err = -ENOENT;
183 
184 	mutex_lock(&xt[af].mutex);
185 	list_for_each_entry(m, &xt[af].match, list) {
186 		if (strcmp(m->name, name) == 0) {
187 			if (m->revision == revision) {
188 				if (try_module_get(m->me)) {
189 					mutex_unlock(&xt[af].mutex);
190 					return m;
191 				}
192 			} else
193 				err = -EPROTOTYPE; /* Found something. */
194 		}
195 	}
196 	mutex_unlock(&xt[af].mutex);
197 
198 	if (af != NFPROTO_UNSPEC)
199 		/* Try searching again in the family-independent list */
200 		return xt_find_match(NFPROTO_UNSPEC, name, revision);
201 
202 	return ERR_PTR(err);
203 }
204 EXPORT_SYMBOL(xt_find_match);
205 
206 struct xt_match *
xt_request_find_match(uint8_t nfproto,const char * name,uint8_t revision)207 xt_request_find_match(uint8_t nfproto, const char *name, uint8_t revision)
208 {
209 	struct xt_match *match;
210 
211 	match = xt_find_match(nfproto, name, revision);
212 	if (IS_ERR(match)) {
213 		request_module("%st_%s", xt_prefix[nfproto], name);
214 		match = xt_find_match(nfproto, name, revision);
215 	}
216 
217 	return match;
218 }
219 EXPORT_SYMBOL_GPL(xt_request_find_match);
220 
221 /* Find target, grabs ref.  Returns ERR_PTR() on error. */
xt_find_target(u8 af,const char * name,u8 revision)222 struct xt_target *xt_find_target(u8 af, const char *name, u8 revision)
223 {
224 	struct xt_target *t;
225 	int err = -ENOENT;
226 
227 	mutex_lock(&xt[af].mutex);
228 	list_for_each_entry(t, &xt[af].target, list) {
229 		if (strcmp(t->name, name) == 0) {
230 			if (t->revision == revision) {
231 				if (try_module_get(t->me)) {
232 					mutex_unlock(&xt[af].mutex);
233 					return t;
234 				}
235 			} else
236 				err = -EPROTOTYPE; /* Found something. */
237 		}
238 	}
239 	mutex_unlock(&xt[af].mutex);
240 
241 	if (af != NFPROTO_UNSPEC)
242 		/* Try searching again in the family-independent list */
243 		return xt_find_target(NFPROTO_UNSPEC, name, revision);
244 
245 	return ERR_PTR(err);
246 }
247 EXPORT_SYMBOL(xt_find_target);
248 
xt_request_find_target(u8 af,const char * name,u8 revision)249 struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision)
250 {
251 	struct xt_target *target;
252 
253 	target = xt_find_target(af, name, revision);
254 	if (IS_ERR(target)) {
255 		request_module("%st_%s", xt_prefix[af], name);
256 		target = xt_find_target(af, name, revision);
257 	}
258 
259 	return target;
260 }
261 EXPORT_SYMBOL_GPL(xt_request_find_target);
262 
match_revfn(u8 af,const char * name,u8 revision,int * bestp)263 static int match_revfn(u8 af, const char *name, u8 revision, int *bestp)
264 {
265 	const struct xt_match *m;
266 	int have_rev = 0;
267 
268 	list_for_each_entry(m, &xt[af].match, list) {
269 		if (strcmp(m->name, name) == 0) {
270 			if (m->revision > *bestp)
271 				*bestp = m->revision;
272 			if (m->revision == revision)
273 				have_rev = 1;
274 		}
275 	}
276 
277 	if (af != NFPROTO_UNSPEC && !have_rev)
278 		return match_revfn(NFPROTO_UNSPEC, name, revision, bestp);
279 
280 	return have_rev;
281 }
282 
target_revfn(u8 af,const char * name,u8 revision,int * bestp)283 static int target_revfn(u8 af, const char *name, u8 revision, int *bestp)
284 {
285 	const struct xt_target *t;
286 	int have_rev = 0;
287 
288 	list_for_each_entry(t, &xt[af].target, list) {
289 		if (strcmp(t->name, name) == 0) {
290 			if (t->revision > *bestp)
291 				*bestp = t->revision;
292 			if (t->revision == revision)
293 				have_rev = 1;
294 		}
295 	}
296 
297 	if (af != NFPROTO_UNSPEC && !have_rev)
298 		return target_revfn(NFPROTO_UNSPEC, name, revision, bestp);
299 
300 	return have_rev;
301 }
302 
303 /* Returns true or false (if no such extension at all) */
xt_find_revision(u8 af,const char * name,u8 revision,int target,int * err)304 int xt_find_revision(u8 af, const char *name, u8 revision, int target,
305 		     int *err)
306 {
307 	int have_rev, best = -1;
308 
309 	mutex_lock(&xt[af].mutex);
310 	if (target == 1)
311 		have_rev = target_revfn(af, name, revision, &best);
312 	else
313 		have_rev = match_revfn(af, name, revision, &best);
314 	mutex_unlock(&xt[af].mutex);
315 
316 	/* Nothing at all?  Return 0 to try loading module. */
317 	if (best == -1) {
318 		*err = -ENOENT;
319 		return 0;
320 	}
321 
322 	*err = best;
323 	if (!have_rev)
324 		*err = -EPROTONOSUPPORT;
325 	return 1;
326 }
327 EXPORT_SYMBOL_GPL(xt_find_revision);
328 
329 static char *
textify_hooks(char * buf,size_t size,unsigned int mask,uint8_t nfproto)330 textify_hooks(char *buf, size_t size, unsigned int mask, uint8_t nfproto)
331 {
332 	static const char *const inetbr_names[] = {
333 		"PREROUTING", "INPUT", "FORWARD",
334 		"OUTPUT", "POSTROUTING", "BROUTING",
335 	};
336 	static const char *const arp_names[] = {
337 		"INPUT", "FORWARD", "OUTPUT",
338 	};
339 	const char *const *names;
340 	unsigned int i, max;
341 	char *p = buf;
342 	bool np = false;
343 	int res;
344 
345 	names = (nfproto == NFPROTO_ARP) ? arp_names : inetbr_names;
346 	max   = (nfproto == NFPROTO_ARP) ? ARRAY_SIZE(arp_names) :
347 	                                   ARRAY_SIZE(inetbr_names);
348 	*p = '\0';
349 	for (i = 0; i < max; ++i) {
350 		if (!(mask & (1 << i)))
351 			continue;
352 		res = snprintf(p, size, "%s%s", np ? "/" : "", names[i]);
353 		if (res > 0) {
354 			size -= res;
355 			p += res;
356 		}
357 		np = true;
358 	}
359 
360 	return buf;
361 }
362 
xt_check_match(struct xt_mtchk_param * par,unsigned int size,u_int8_t proto,bool inv_proto)363 int xt_check_match(struct xt_mtchk_param *par,
364 		   unsigned int size, u_int8_t proto, bool inv_proto)
365 {
366 	int ret;
367 
368 	if (XT_ALIGN(par->match->matchsize) != size &&
369 	    par->match->matchsize != -1) {
370 		/*
371 		 * ebt_among is exempt from centralized matchsize checking
372 		 * because it uses a dynamic-size data set.
373 		 */
374 		pr_err("%s_tables: %s.%u match: invalid size "
375 		       "%u (kernel) != (user) %u\n",
376 		       xt_prefix[par->family], par->match->name,
377 		       par->match->revision,
378 		       XT_ALIGN(par->match->matchsize), size);
379 		return -EINVAL;
380 	}
381 	if (par->match->table != NULL &&
382 	    strcmp(par->match->table, par->table) != 0) {
383 		pr_err("%s_tables: %s match: only valid in %s table, not %s\n",
384 		       xt_prefix[par->family], par->match->name,
385 		       par->match->table, par->table);
386 		return -EINVAL;
387 	}
388 	if (par->match->hooks && (par->hook_mask & ~par->match->hooks) != 0) {
389 		char used[64], allow[64];
390 
391 		pr_err("%s_tables: %s match: used from hooks %s, but only "
392 		       "valid from %s\n",
393 		       xt_prefix[par->family], par->match->name,
394 		       textify_hooks(used, sizeof(used), par->hook_mask,
395 		                     par->family),
396 		       textify_hooks(allow, sizeof(allow), par->match->hooks,
397 		                     par->family));
398 		return -EINVAL;
399 	}
400 	if (par->match->proto && (par->match->proto != proto || inv_proto)) {
401 		pr_err("%s_tables: %s match: only valid for protocol %u\n",
402 		       xt_prefix[par->family], par->match->name,
403 		       par->match->proto);
404 		return -EINVAL;
405 	}
406 	if (par->match->checkentry != NULL) {
407 		ret = par->match->checkentry(par);
408 		if (ret < 0)
409 			return ret;
410 		else if (ret > 0)
411 			/* Flag up potential errors. */
412 			return -EIO;
413 	}
414 	return 0;
415 }
416 EXPORT_SYMBOL_GPL(xt_check_match);
417 
418 /** xt_check_entry_match - check that matches end before start of target
419  *
420  * @match: beginning of xt_entry_match
421  * @target: beginning of this rules target (alleged end of matches)
422  * @alignment: alignment requirement of match structures
423  *
424  * Validates that all matches add up to the beginning of the target,
425  * and that each match covers at least the base structure size.
426  *
427  * Return: 0 on success, negative errno on failure.
428  */
xt_check_entry_match(const char * match,const char * target,const size_t alignment)429 static int xt_check_entry_match(const char *match, const char *target,
430 				const size_t alignment)
431 {
432 	const struct xt_entry_match *pos;
433 	int length = target - match;
434 
435 	if (length == 0) /* no matches */
436 		return 0;
437 
438 	pos = (struct xt_entry_match *)match;
439 	do {
440 		if ((unsigned long)pos % alignment)
441 			return -EINVAL;
442 
443 		if (length < (int)sizeof(struct xt_entry_match))
444 			return -EINVAL;
445 
446 		if (pos->u.match_size < sizeof(struct xt_entry_match))
447 			return -EINVAL;
448 
449 		if (pos->u.match_size > length)
450 			return -EINVAL;
451 
452 		length -= pos->u.match_size;
453 		pos = ((void *)((char *)(pos) + (pos)->u.match_size));
454 	} while (length > 0);
455 
456 	return 0;
457 }
458 
459 #ifdef CONFIG_COMPAT
xt_compat_add_offset(u_int8_t af,unsigned int offset,int delta)460 int xt_compat_add_offset(u_int8_t af, unsigned int offset, int delta)
461 {
462 	struct xt_af *xp = &xt[af];
463 
464 	if (!xp->compat_tab) {
465 		if (!xp->number)
466 			return -EINVAL;
467 		xp->compat_tab = vmalloc(sizeof(struct compat_delta) * xp->number);
468 		if (!xp->compat_tab)
469 			return -ENOMEM;
470 		xp->cur = 0;
471 	}
472 
473 	if (xp->cur >= xp->number)
474 		return -EINVAL;
475 
476 	if (xp->cur)
477 		delta += xp->compat_tab[xp->cur - 1].delta;
478 	xp->compat_tab[xp->cur].offset = offset;
479 	xp->compat_tab[xp->cur].delta = delta;
480 	xp->cur++;
481 	return 0;
482 }
483 EXPORT_SYMBOL_GPL(xt_compat_add_offset);
484 
xt_compat_flush_offsets(u_int8_t af)485 void xt_compat_flush_offsets(u_int8_t af)
486 {
487 	if (xt[af].compat_tab) {
488 		vfree(xt[af].compat_tab);
489 		xt[af].compat_tab = NULL;
490 		xt[af].number = 0;
491 		xt[af].cur = 0;
492 	}
493 }
494 EXPORT_SYMBOL_GPL(xt_compat_flush_offsets);
495 
xt_compat_calc_jump(u_int8_t af,unsigned int offset)496 int xt_compat_calc_jump(u_int8_t af, unsigned int offset)
497 {
498 	struct compat_delta *tmp = xt[af].compat_tab;
499 	int mid, left = 0, right = xt[af].cur - 1;
500 
501 	while (left <= right) {
502 		mid = (left + right) >> 1;
503 		if (offset > tmp[mid].offset)
504 			left = mid + 1;
505 		else if (offset < tmp[mid].offset)
506 			right = mid - 1;
507 		else
508 			return mid ? tmp[mid - 1].delta : 0;
509 	}
510 	return left ? tmp[left - 1].delta : 0;
511 }
512 EXPORT_SYMBOL_GPL(xt_compat_calc_jump);
513 
xt_compat_init_offsets(u_int8_t af,unsigned int number)514 void xt_compat_init_offsets(u_int8_t af, unsigned int number)
515 {
516 	xt[af].number = number;
517 	xt[af].cur = 0;
518 }
519 EXPORT_SYMBOL(xt_compat_init_offsets);
520 
xt_compat_match_offset(const struct xt_match * match)521 int xt_compat_match_offset(const struct xt_match *match)
522 {
523 	u_int16_t csize = match->compatsize ? : match->matchsize;
524 	return XT_ALIGN(match->matchsize) - COMPAT_XT_ALIGN(csize);
525 }
526 EXPORT_SYMBOL_GPL(xt_compat_match_offset);
527 
xt_compat_match_from_user(struct xt_entry_match * m,void ** dstptr,unsigned int * size)528 void xt_compat_match_from_user(struct xt_entry_match *m, void **dstptr,
529 			       unsigned int *size)
530 {
531 	const struct xt_match *match = m->u.kernel.match;
532 	struct compat_xt_entry_match *cm = (struct compat_xt_entry_match *)m;
533 	int pad, off = xt_compat_match_offset(match);
534 	u_int16_t msize = cm->u.user.match_size;
535 	char name[sizeof(m->u.user.name)];
536 
537 	m = *dstptr;
538 	memcpy(m, cm, sizeof(*cm));
539 	if (match->compat_from_user)
540 		match->compat_from_user(m->data, cm->data);
541 	else
542 		memcpy(m->data, cm->data, msize - sizeof(*cm));
543 	pad = XT_ALIGN(match->matchsize) - match->matchsize;
544 	if (pad > 0)
545 		memset(m->data + match->matchsize, 0, pad);
546 
547 	msize += off;
548 	m->u.user.match_size = msize;
549 	strlcpy(name, match->name, sizeof(name));
550 	module_put(match->me);
551 	strncpy(m->u.user.name, name, sizeof(m->u.user.name));
552 
553 	*size += off;
554 	*dstptr += msize;
555 }
556 EXPORT_SYMBOL_GPL(xt_compat_match_from_user);
557 
xt_compat_match_to_user(const struct xt_entry_match * m,void __user ** dstptr,unsigned int * size)558 int xt_compat_match_to_user(const struct xt_entry_match *m,
559 			    void __user **dstptr, unsigned int *size)
560 {
561 	const struct xt_match *match = m->u.kernel.match;
562 	struct compat_xt_entry_match __user *cm = *dstptr;
563 	int off = xt_compat_match_offset(match);
564 	u_int16_t msize = m->u.user.match_size - off;
565 
566 	if (copy_to_user(cm, m, sizeof(*cm)) ||
567 	    put_user(msize, &cm->u.user.match_size) ||
568 	    copy_to_user(cm->u.user.name, m->u.kernel.match->name,
569 			 strlen(m->u.kernel.match->name) + 1))
570 		return -EFAULT;
571 
572 	if (match->compat_to_user) {
573 		if (match->compat_to_user((void __user *)cm->data, m->data))
574 			return -EFAULT;
575 	} else {
576 		if (copy_to_user(cm->data, m->data, msize - sizeof(*cm)))
577 			return -EFAULT;
578 	}
579 
580 	*size -= off;
581 	*dstptr += msize;
582 	return 0;
583 }
584 EXPORT_SYMBOL_GPL(xt_compat_match_to_user);
585 
586 /* non-compat version may have padding after verdict */
587 struct compat_xt_standard_target {
588 	struct compat_xt_entry_target t;
589 	compat_uint_t verdict;
590 };
591 
xt_compat_check_entry_offsets(const void * base,const char * elems,unsigned int target_offset,unsigned int next_offset)592 int xt_compat_check_entry_offsets(const void *base, const char *elems,
593 				  unsigned int target_offset,
594 				  unsigned int next_offset)
595 {
596 	long size_of_base_struct = elems - (const char *)base;
597 	const struct compat_xt_entry_target *t;
598 	const char *e = base;
599 
600 	if (target_offset < size_of_base_struct)
601 		return -EINVAL;
602 
603 	if (target_offset + sizeof(*t) > next_offset)
604 		return -EINVAL;
605 
606 	t = (void *)(e + target_offset);
607 	if (t->u.target_size < sizeof(*t))
608 		return -EINVAL;
609 
610 	if (target_offset + t->u.target_size > next_offset)
611 		return -EINVAL;
612 
613 	if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 &&
614 	    COMPAT_XT_ALIGN(target_offset + sizeof(struct compat_xt_standard_target)) != next_offset)
615 		return -EINVAL;
616 
617 	/* compat_xt_entry match has less strict aligment requirements,
618 	 * otherwise they are identical.  In case of padding differences
619 	 * we need to add compat version of xt_check_entry_match.
620 	 */
621 	BUILD_BUG_ON(sizeof(struct compat_xt_entry_match) != sizeof(struct xt_entry_match));
622 
623 	return xt_check_entry_match(elems, base + target_offset,
624 				    __alignof__(struct compat_xt_entry_match));
625 }
626 EXPORT_SYMBOL(xt_compat_check_entry_offsets);
627 #endif /* CONFIG_COMPAT */
628 
629 /**
630  * xt_check_entry_offsets - validate arp/ip/ip6t_entry
631  *
632  * @base: pointer to arp/ip/ip6t_entry
633  * @elems: pointer to first xt_entry_match, i.e. ip(6)t_entry->elems
634  * @target_offset: the arp/ip/ip6_t->target_offset
635  * @next_offset: the arp/ip/ip6_t->next_offset
636  *
637  * validates that target_offset and next_offset are sane and that all
638  * match sizes (if any) align with the target offset.
639  *
640  * This function does not validate the targets or matches themselves, it
641  * only tests that all the offsets and sizes are correct, that all
642  * match structures are aligned, and that the last structure ends where
643  * the target structure begins.
644  *
645  * Also see xt_compat_check_entry_offsets for CONFIG_COMPAT version.
646  *
647  * The arp/ip/ip6t_entry structure @base must have passed following tests:
648  * - it must point to a valid memory location
649  * - base to base + next_offset must be accessible, i.e. not exceed allocated
650  *   length.
651  *
652  * A well-formed entry looks like this:
653  *
654  * ip(6)t_entry   match [mtdata]  match [mtdata] target [tgdata] ip(6)t_entry
655  * e->elems[]-----'                              |               |
656  *                matchsize                      |               |
657  *                                matchsize      |               |
658  *                                               |               |
659  * target_offset---------------------------------'               |
660  * next_offset---------------------------------------------------'
661  *
662  * elems[]: flexible array member at end of ip(6)/arpt_entry struct.
663  *          This is where matches (if any) and the target reside.
664  * target_offset: beginning of target.
665  * next_offset: start of the next rule; also: size of this rule.
666  * Since targets have a minimum size, target_offset + minlen <= next_offset.
667  *
668  * Every match stores its size, sum of sizes must not exceed target_offset.
669  *
670  * Return: 0 on success, negative errno on failure.
671  */
xt_check_entry_offsets(const void * base,const char * elems,unsigned int target_offset,unsigned int next_offset)672 int xt_check_entry_offsets(const void *base,
673 			   const char *elems,
674 			   unsigned int target_offset,
675 			   unsigned int next_offset)
676 {
677 	long size_of_base_struct = elems - (const char *)base;
678 	const struct xt_entry_target *t;
679 	const char *e = base;
680 
681 	/* target start is within the ip/ip6/arpt_entry struct */
682 	if (target_offset < size_of_base_struct)
683 		return -EINVAL;
684 
685 	if (target_offset + sizeof(*t) > next_offset)
686 		return -EINVAL;
687 
688 	t = (void *)(e + target_offset);
689 	if (t->u.target_size < sizeof(*t))
690 		return -EINVAL;
691 
692 	if (target_offset + t->u.target_size > next_offset)
693 		return -EINVAL;
694 
695 	if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 &&
696 	    XT_ALIGN(target_offset + sizeof(struct xt_standard_target)) != next_offset)
697 		return -EINVAL;
698 
699 	return xt_check_entry_match(elems, base + target_offset,
700 				    __alignof__(struct xt_entry_match));
701 }
702 EXPORT_SYMBOL(xt_check_entry_offsets);
703 
xt_check_target(struct xt_tgchk_param * par,unsigned int size,u_int8_t proto,bool inv_proto)704 int xt_check_target(struct xt_tgchk_param *par,
705 		    unsigned int size, u_int8_t proto, bool inv_proto)
706 {
707 	int ret;
708 
709 	if (XT_ALIGN(par->target->targetsize) != size) {
710 		pr_err("%s_tables: %s.%u target: invalid size "
711 		       "%u (kernel) != (user) %u\n",
712 		       xt_prefix[par->family], par->target->name,
713 		       par->target->revision,
714 		       XT_ALIGN(par->target->targetsize), size);
715 		return -EINVAL;
716 	}
717 	if (par->target->table != NULL &&
718 	    strcmp(par->target->table, par->table) != 0) {
719 		pr_err("%s_tables: %s target: only valid in %s table, not %s\n",
720 		       xt_prefix[par->family], par->target->name,
721 		       par->target->table, par->table);
722 		return -EINVAL;
723 	}
724 	if (par->target->hooks && (par->hook_mask & ~par->target->hooks) != 0) {
725 		char used[64], allow[64];
726 
727 		pr_err("%s_tables: %s target: used from hooks %s, but only "
728 		       "usable from %s\n",
729 		       xt_prefix[par->family], par->target->name,
730 		       textify_hooks(used, sizeof(used), par->hook_mask,
731 		                     par->family),
732 		       textify_hooks(allow, sizeof(allow), par->target->hooks,
733 		                     par->family));
734 		return -EINVAL;
735 	}
736 	if (par->target->proto && (par->target->proto != proto || inv_proto)) {
737 		pr_err("%s_tables: %s target: only valid for protocol %u\n",
738 		       xt_prefix[par->family], par->target->name,
739 		       par->target->proto);
740 		return -EINVAL;
741 	}
742 	if (par->target->checkentry != NULL) {
743 		ret = par->target->checkentry(par);
744 		if (ret < 0)
745 			return ret;
746 		else if (ret > 0)
747 			/* Flag up potential errors. */
748 			return -EIO;
749 	}
750 	return 0;
751 }
752 EXPORT_SYMBOL_GPL(xt_check_target);
753 
754 /**
755  * xt_copy_counters_from_user - copy counters and metadata from userspace
756  *
757  * @user: src pointer to userspace memory
758  * @len: alleged size of userspace memory
759  * @info: where to store the xt_counters_info metadata
760  * @compat: true if we setsockopt call is done by 32bit task on 64bit kernel
761  *
762  * Copies counter meta data from @user and stores it in @info.
763  *
764  * vmallocs memory to hold the counters, then copies the counter data
765  * from @user to the new memory and returns a pointer to it.
766  *
767  * If @compat is true, @info gets converted automatically to the 64bit
768  * representation.
769  *
770  * The metadata associated with the counters is stored in @info.
771  *
772  * Return: returns pointer that caller has to test via IS_ERR().
773  * If IS_ERR is false, caller has to vfree the pointer.
774  */
xt_copy_counters_from_user(const void __user * user,unsigned int len,struct xt_counters_info * info,bool compat)775 void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
776 				 struct xt_counters_info *info, bool compat)
777 {
778 	void *mem;
779 	u64 size;
780 
781 #ifdef CONFIG_COMPAT
782 	if (compat) {
783 		/* structures only differ in size due to alignment */
784 		struct compat_xt_counters_info compat_tmp;
785 
786 		if (len <= sizeof(compat_tmp))
787 			return ERR_PTR(-EINVAL);
788 
789 		len -= sizeof(compat_tmp);
790 		if (copy_from_user(&compat_tmp, user, sizeof(compat_tmp)) != 0)
791 			return ERR_PTR(-EFAULT);
792 
793 		strlcpy(info->name, compat_tmp.name, sizeof(info->name));
794 		info->num_counters = compat_tmp.num_counters;
795 		user += sizeof(compat_tmp);
796 	} else
797 #endif
798 	{
799 		if (len <= sizeof(*info))
800 			return ERR_PTR(-EINVAL);
801 
802 		len -= sizeof(*info);
803 		if (copy_from_user(info, user, sizeof(*info)) != 0)
804 			return ERR_PTR(-EFAULT);
805 
806 		info->name[sizeof(info->name) - 1] = '\0';
807 		user += sizeof(*info);
808 	}
809 
810 	size = sizeof(struct xt_counters);
811 	size *= info->num_counters;
812 
813 	if (size != (u64)len)
814 		return ERR_PTR(-EINVAL);
815 
816 	mem = vmalloc(len);
817 	if (!mem)
818 		return ERR_PTR(-ENOMEM);
819 
820 	if (copy_from_user(mem, user, len) == 0)
821 		return mem;
822 
823 	vfree(mem);
824 	return ERR_PTR(-EFAULT);
825 }
826 EXPORT_SYMBOL_GPL(xt_copy_counters_from_user);
827 
828 #ifdef CONFIG_COMPAT
xt_compat_target_offset(const struct xt_target * target)829 int xt_compat_target_offset(const struct xt_target *target)
830 {
831 	u_int16_t csize = target->compatsize ? : target->targetsize;
832 	return XT_ALIGN(target->targetsize) - COMPAT_XT_ALIGN(csize);
833 }
834 EXPORT_SYMBOL_GPL(xt_compat_target_offset);
835 
xt_compat_target_from_user(struct xt_entry_target * t,void ** dstptr,unsigned int * size)836 void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,
837 				unsigned int *size)
838 {
839 	const struct xt_target *target = t->u.kernel.target;
840 	struct compat_xt_entry_target *ct = (struct compat_xt_entry_target *)t;
841 	int pad, off = xt_compat_target_offset(target);
842 	u_int16_t tsize = ct->u.user.target_size;
843 	char name[sizeof(t->u.user.name)];
844 
845 	t = *dstptr;
846 	memcpy(t, ct, sizeof(*ct));
847 	if (target->compat_from_user)
848 		target->compat_from_user(t->data, ct->data);
849 	else
850 		memcpy(t->data, ct->data, tsize - sizeof(*ct));
851 	pad = XT_ALIGN(target->targetsize) - target->targetsize;
852 	if (pad > 0)
853 		memset(t->data + target->targetsize, 0, pad);
854 
855 	tsize += off;
856 	t->u.user.target_size = tsize;
857 	strlcpy(name, target->name, sizeof(name));
858 	module_put(target->me);
859 	strncpy(t->u.user.name, name, sizeof(t->u.user.name));
860 
861 	*size += off;
862 	*dstptr += tsize;
863 }
864 EXPORT_SYMBOL_GPL(xt_compat_target_from_user);
865 
xt_compat_target_to_user(const struct xt_entry_target * t,void __user ** dstptr,unsigned int * size)866 int xt_compat_target_to_user(const struct xt_entry_target *t,
867 			     void __user **dstptr, unsigned int *size)
868 {
869 	const struct xt_target *target = t->u.kernel.target;
870 	struct compat_xt_entry_target __user *ct = *dstptr;
871 	int off = xt_compat_target_offset(target);
872 	u_int16_t tsize = t->u.user.target_size - off;
873 
874 	if (copy_to_user(ct, t, sizeof(*ct)) ||
875 	    put_user(tsize, &ct->u.user.target_size) ||
876 	    copy_to_user(ct->u.user.name, t->u.kernel.target->name,
877 			 strlen(t->u.kernel.target->name) + 1))
878 		return -EFAULT;
879 
880 	if (target->compat_to_user) {
881 		if (target->compat_to_user((void __user *)ct->data, t->data))
882 			return -EFAULT;
883 	} else {
884 		if (copy_to_user(ct->data, t->data, tsize - sizeof(*ct)))
885 			return -EFAULT;
886 	}
887 
888 	*size -= off;
889 	*dstptr += tsize;
890 	return 0;
891 }
892 EXPORT_SYMBOL_GPL(xt_compat_target_to_user);
893 #endif
894 
xt_alloc_table_info(unsigned int size)895 struct xt_table_info *xt_alloc_table_info(unsigned int size)
896 {
897 	struct xt_table_info *info = NULL;
898 	size_t sz = sizeof(*info) + size;
899 
900 	/* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
901 	if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > totalram_pages)
902 		return NULL;
903 
904 	if (sz <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER))
905 		info = kmalloc(sz, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
906 	if (!info) {
907 		info = vmalloc(sz);
908 		if (!info)
909 			return NULL;
910 	}
911 	memset(info, 0, sizeof(*info));
912 	info->size = size;
913 	return info;
914 }
915 EXPORT_SYMBOL(xt_alloc_table_info);
916 
xt_free_table_info(struct xt_table_info * info)917 void xt_free_table_info(struct xt_table_info *info)
918 {
919 	int cpu;
920 
921 	if (info->jumpstack != NULL) {
922 		for_each_possible_cpu(cpu)
923 			kvfree(info->jumpstack[cpu]);
924 		kvfree(info->jumpstack);
925 	}
926 
927 	kvfree(info);
928 }
929 EXPORT_SYMBOL(xt_free_table_info);
930 
931 /* Find table by name, grabs mutex & ref.  Returns ERR_PTR() on error. */
xt_find_table_lock(struct net * net,u_int8_t af,const char * name)932 struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
933 				    const char *name)
934 {
935 	struct xt_table *t;
936 
937 	mutex_lock(&xt[af].mutex);
938 	list_for_each_entry(t, &net->xt.tables[af], list)
939 		if (strcmp(t->name, name) == 0 && try_module_get(t->me))
940 			return t;
941 	mutex_unlock(&xt[af].mutex);
942 	return NULL;
943 }
944 EXPORT_SYMBOL_GPL(xt_find_table_lock);
945 
xt_table_unlock(struct xt_table * table)946 void xt_table_unlock(struct xt_table *table)
947 {
948 	mutex_unlock(&xt[table->af].mutex);
949 }
950 EXPORT_SYMBOL_GPL(xt_table_unlock);
951 
952 #ifdef CONFIG_COMPAT
xt_compat_lock(u_int8_t af)953 void xt_compat_lock(u_int8_t af)
954 {
955 	mutex_lock(&xt[af].compat_mutex);
956 }
957 EXPORT_SYMBOL_GPL(xt_compat_lock);
958 
xt_compat_unlock(u_int8_t af)959 void xt_compat_unlock(u_int8_t af)
960 {
961 	mutex_unlock(&xt[af].compat_mutex);
962 }
963 EXPORT_SYMBOL_GPL(xt_compat_unlock);
964 #endif
965 
966 DEFINE_PER_CPU(seqcount_t, xt_recseq);
967 EXPORT_PER_CPU_SYMBOL_GPL(xt_recseq);
968 
969 struct static_key xt_tee_enabled __read_mostly;
970 EXPORT_SYMBOL_GPL(xt_tee_enabled);
971 
xt_jumpstack_alloc(struct xt_table_info * i)972 static int xt_jumpstack_alloc(struct xt_table_info *i)
973 {
974 	unsigned int size;
975 	int cpu;
976 
977 	size = sizeof(void **) * nr_cpu_ids;
978 	if (size > PAGE_SIZE)
979 		i->jumpstack = vzalloc(size);
980 	else
981 		i->jumpstack = kzalloc(size, GFP_KERNEL);
982 	if (i->jumpstack == NULL)
983 		return -ENOMEM;
984 
985 	/* ruleset without jumps -- no stack needed */
986 	if (i->stacksize == 0)
987 		return 0;
988 
989 	/* Jumpstack needs to be able to record two full callchains, one
990 	 * from the first rule set traversal, plus one table reentrancy
991 	 * via -j TEE without clobbering the callchain that brought us to
992 	 * TEE target.
993 	 *
994 	 * This is done by allocating two jumpstacks per cpu, on reentry
995 	 * the upper half of the stack is used.
996 	 *
997 	 * see the jumpstack setup in ipt_do_table() for more details.
998 	 */
999 	size = sizeof(void *) * i->stacksize * 2u;
1000 	for_each_possible_cpu(cpu) {
1001 		if (size > PAGE_SIZE)
1002 			i->jumpstack[cpu] = vmalloc_node(size,
1003 				cpu_to_node(cpu));
1004 		else
1005 			i->jumpstack[cpu] = kmalloc_node(size,
1006 				GFP_KERNEL, cpu_to_node(cpu));
1007 		if (i->jumpstack[cpu] == NULL)
1008 			/*
1009 			 * Freeing will be done later on by the callers. The
1010 			 * chain is: xt_replace_table -> __do_replace ->
1011 			 * do_replace -> xt_free_table_info.
1012 			 */
1013 			return -ENOMEM;
1014 	}
1015 
1016 	return 0;
1017 }
1018 
1019 struct xt_table_info *
xt_replace_table(struct xt_table * table,unsigned int num_counters,struct xt_table_info * newinfo,int * error)1020 xt_replace_table(struct xt_table *table,
1021 	      unsigned int num_counters,
1022 	      struct xt_table_info *newinfo,
1023 	      int *error)
1024 {
1025 	struct xt_table_info *private;
1026 	int ret;
1027 
1028 	ret = xt_jumpstack_alloc(newinfo);
1029 	if (ret < 0) {
1030 		*error = ret;
1031 		return NULL;
1032 	}
1033 
1034 	/* Do the substitution. */
1035 	local_bh_disable();
1036 	private = table->private;
1037 
1038 	/* Check inside lock: is the old number correct? */
1039 	if (num_counters != private->number) {
1040 		pr_debug("num_counters != table->private->number (%u/%u)\n",
1041 			 num_counters, private->number);
1042 		local_bh_enable();
1043 		*error = -EAGAIN;
1044 		return NULL;
1045 	}
1046 
1047 	newinfo->initial_entries = private->initial_entries;
1048 	/*
1049 	 * Ensure contents of newinfo are visible before assigning to
1050 	 * private.
1051 	 */
1052 	smp_wmb();
1053 	table->private = newinfo;
1054 
1055 	/*
1056 	 * Even though table entries have now been swapped, other CPU's
1057 	 * may still be using the old entries. This is okay, because
1058 	 * resynchronization happens because of the locking done
1059 	 * during the get_counters() routine.
1060 	 */
1061 	local_bh_enable();
1062 
1063 #ifdef CONFIG_AUDIT
1064 	if (audit_enabled) {
1065 		struct audit_buffer *ab;
1066 
1067 		ab = audit_log_start(current->audit_context, GFP_KERNEL,
1068 				     AUDIT_NETFILTER_CFG);
1069 		if (ab) {
1070 			audit_log_format(ab, "table=%s family=%u entries=%u",
1071 					 table->name, table->af,
1072 					 private->number);
1073 			audit_log_end(ab);
1074 		}
1075 	}
1076 #endif
1077 
1078 	return private;
1079 }
1080 EXPORT_SYMBOL_GPL(xt_replace_table);
1081 
xt_register_table(struct net * net,const struct xt_table * input_table,struct xt_table_info * bootstrap,struct xt_table_info * newinfo)1082 struct xt_table *xt_register_table(struct net *net,
1083 				   const struct xt_table *input_table,
1084 				   struct xt_table_info *bootstrap,
1085 				   struct xt_table_info *newinfo)
1086 {
1087 	int ret;
1088 	struct xt_table_info *private;
1089 	struct xt_table *t, *table;
1090 
1091 	/* Don't add one object to multiple lists. */
1092 	table = kmemdup(input_table, sizeof(struct xt_table), GFP_KERNEL);
1093 	if (!table) {
1094 		ret = -ENOMEM;
1095 		goto out;
1096 	}
1097 
1098 	mutex_lock(&xt[table->af].mutex);
1099 	/* Don't autoload: we'd eat our tail... */
1100 	list_for_each_entry(t, &net->xt.tables[table->af], list) {
1101 		if (strcmp(t->name, table->name) == 0) {
1102 			ret = -EEXIST;
1103 			goto unlock;
1104 		}
1105 	}
1106 
1107 	/* Simplifies replace_table code. */
1108 	table->private = bootstrap;
1109 
1110 	if (!xt_replace_table(table, 0, newinfo, &ret))
1111 		goto unlock;
1112 
1113 	private = table->private;
1114 	pr_debug("table->private->number = %u\n", private->number);
1115 
1116 	/* save number of initial entries */
1117 	private->initial_entries = private->number;
1118 
1119 	list_add(&table->list, &net->xt.tables[table->af]);
1120 	mutex_unlock(&xt[table->af].mutex);
1121 	return table;
1122 
1123 unlock:
1124 	mutex_unlock(&xt[table->af].mutex);
1125 	kfree(table);
1126 out:
1127 	return ERR_PTR(ret);
1128 }
1129 EXPORT_SYMBOL_GPL(xt_register_table);
1130 
xt_unregister_table(struct xt_table * table)1131 void *xt_unregister_table(struct xt_table *table)
1132 {
1133 	struct xt_table_info *private;
1134 
1135 	mutex_lock(&xt[table->af].mutex);
1136 	private = table->private;
1137 	list_del(&table->list);
1138 	mutex_unlock(&xt[table->af].mutex);
1139 	kfree(table);
1140 
1141 	return private;
1142 }
1143 EXPORT_SYMBOL_GPL(xt_unregister_table);
1144 
1145 #ifdef CONFIG_PROC_FS
1146 struct xt_names_priv {
1147 	struct seq_net_private p;
1148 	u_int8_t af;
1149 };
xt_table_seq_start(struct seq_file * seq,loff_t * pos)1150 static void *xt_table_seq_start(struct seq_file *seq, loff_t *pos)
1151 {
1152 	struct xt_names_priv *priv = seq->private;
1153 	struct net *net = seq_file_net(seq);
1154 	u_int8_t af = priv->af;
1155 
1156 	mutex_lock(&xt[af].mutex);
1157 	return seq_list_start(&net->xt.tables[af], *pos);
1158 }
1159 
xt_table_seq_next(struct seq_file * seq,void * v,loff_t * pos)1160 static void *xt_table_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1161 {
1162 	struct xt_names_priv *priv = seq->private;
1163 	struct net *net = seq_file_net(seq);
1164 	u_int8_t af = priv->af;
1165 
1166 	return seq_list_next(v, &net->xt.tables[af], pos);
1167 }
1168 
xt_table_seq_stop(struct seq_file * seq,void * v)1169 static void xt_table_seq_stop(struct seq_file *seq, void *v)
1170 {
1171 	struct xt_names_priv *priv = seq->private;
1172 	u_int8_t af = priv->af;
1173 
1174 	mutex_unlock(&xt[af].mutex);
1175 }
1176 
xt_table_seq_show(struct seq_file * seq,void * v)1177 static int xt_table_seq_show(struct seq_file *seq, void *v)
1178 {
1179 	struct xt_table *table = list_entry(v, struct xt_table, list);
1180 
1181 	if (*table->name)
1182 		seq_printf(seq, "%s\n", table->name);
1183 	return 0;
1184 }
1185 
1186 static const struct seq_operations xt_table_seq_ops = {
1187 	.start	= xt_table_seq_start,
1188 	.next	= xt_table_seq_next,
1189 	.stop	= xt_table_seq_stop,
1190 	.show	= xt_table_seq_show,
1191 };
1192 
xt_table_open(struct inode * inode,struct file * file)1193 static int xt_table_open(struct inode *inode, struct file *file)
1194 {
1195 	int ret;
1196 	struct xt_names_priv *priv;
1197 
1198 	ret = seq_open_net(inode, file, &xt_table_seq_ops,
1199 			   sizeof(struct xt_names_priv));
1200 	if (!ret) {
1201 		priv = ((struct seq_file *)file->private_data)->private;
1202 		priv->af = (unsigned long)PDE_DATA(inode);
1203 	}
1204 	return ret;
1205 }
1206 
1207 static const struct file_operations xt_table_ops = {
1208 	.owner	 = THIS_MODULE,
1209 	.open	 = xt_table_open,
1210 	.read	 = seq_read,
1211 	.llseek	 = seq_lseek,
1212 	.release = seq_release_net,
1213 };
1214 
1215 /*
1216  * Traverse state for ip{,6}_{tables,matches} for helping crossing
1217  * the multi-AF mutexes.
1218  */
1219 struct nf_mttg_trav {
1220 	struct list_head *head, *curr;
1221 	uint8_t class, nfproto;
1222 };
1223 
1224 enum {
1225 	MTTG_TRAV_INIT,
1226 	MTTG_TRAV_NFP_UNSPEC,
1227 	MTTG_TRAV_NFP_SPEC,
1228 	MTTG_TRAV_DONE,
1229 };
1230 
xt_mttg_seq_next(struct seq_file * seq,void * v,loff_t * ppos,bool is_target)1231 static void *xt_mttg_seq_next(struct seq_file *seq, void *v, loff_t *ppos,
1232     bool is_target)
1233 {
1234 	static const uint8_t next_class[] = {
1235 		[MTTG_TRAV_NFP_UNSPEC] = MTTG_TRAV_NFP_SPEC,
1236 		[MTTG_TRAV_NFP_SPEC]   = MTTG_TRAV_DONE,
1237 	};
1238 	struct nf_mttg_trav *trav = seq->private;
1239 
1240 	switch (trav->class) {
1241 	case MTTG_TRAV_INIT:
1242 		trav->class = MTTG_TRAV_NFP_UNSPEC;
1243 		mutex_lock(&xt[NFPROTO_UNSPEC].mutex);
1244 		trav->head = trav->curr = is_target ?
1245 			&xt[NFPROTO_UNSPEC].target : &xt[NFPROTO_UNSPEC].match;
1246  		break;
1247 	case MTTG_TRAV_NFP_UNSPEC:
1248 		trav->curr = trav->curr->next;
1249 		if (trav->curr != trav->head)
1250 			break;
1251 		mutex_unlock(&xt[NFPROTO_UNSPEC].mutex);
1252 		mutex_lock(&xt[trav->nfproto].mutex);
1253 		trav->head = trav->curr = is_target ?
1254 			&xt[trav->nfproto].target : &xt[trav->nfproto].match;
1255 		trav->class = next_class[trav->class];
1256 		break;
1257 	case MTTG_TRAV_NFP_SPEC:
1258 		trav->curr = trav->curr->next;
1259 		if (trav->curr != trav->head)
1260 			break;
1261 		/* fallthru, _stop will unlock */
1262 	default:
1263 		return NULL;
1264 	}
1265 
1266 	if (ppos != NULL)
1267 		++*ppos;
1268 	return trav;
1269 }
1270 
xt_mttg_seq_start(struct seq_file * seq,loff_t * pos,bool is_target)1271 static void *xt_mttg_seq_start(struct seq_file *seq, loff_t *pos,
1272     bool is_target)
1273 {
1274 	struct nf_mttg_trav *trav = seq->private;
1275 	unsigned int j;
1276 
1277 	trav->class = MTTG_TRAV_INIT;
1278 	for (j = 0; j < *pos; ++j)
1279 		if (xt_mttg_seq_next(seq, NULL, NULL, is_target) == NULL)
1280 			return NULL;
1281 	return trav;
1282 }
1283 
xt_mttg_seq_stop(struct seq_file * seq,void * v)1284 static void xt_mttg_seq_stop(struct seq_file *seq, void *v)
1285 {
1286 	struct nf_mttg_trav *trav = seq->private;
1287 
1288 	switch (trav->class) {
1289 	case MTTG_TRAV_NFP_UNSPEC:
1290 		mutex_unlock(&xt[NFPROTO_UNSPEC].mutex);
1291 		break;
1292 	case MTTG_TRAV_NFP_SPEC:
1293 		mutex_unlock(&xt[trav->nfproto].mutex);
1294 		break;
1295 	}
1296 }
1297 
xt_match_seq_start(struct seq_file * seq,loff_t * pos)1298 static void *xt_match_seq_start(struct seq_file *seq, loff_t *pos)
1299 {
1300 	return xt_mttg_seq_start(seq, pos, false);
1301 }
1302 
xt_match_seq_next(struct seq_file * seq,void * v,loff_t * ppos)1303 static void *xt_match_seq_next(struct seq_file *seq, void *v, loff_t *ppos)
1304 {
1305 	return xt_mttg_seq_next(seq, v, ppos, false);
1306 }
1307 
xt_match_seq_show(struct seq_file * seq,void * v)1308 static int xt_match_seq_show(struct seq_file *seq, void *v)
1309 {
1310 	const struct nf_mttg_trav *trav = seq->private;
1311 	const struct xt_match *match;
1312 
1313 	switch (trav->class) {
1314 	case MTTG_TRAV_NFP_UNSPEC:
1315 	case MTTG_TRAV_NFP_SPEC:
1316 		if (trav->curr == trav->head)
1317 			return 0;
1318 		match = list_entry(trav->curr, struct xt_match, list);
1319 		if (*match->name)
1320 			seq_printf(seq, "%s\n", match->name);
1321 	}
1322 	return 0;
1323 }
1324 
1325 static const struct seq_operations xt_match_seq_ops = {
1326 	.start	= xt_match_seq_start,
1327 	.next	= xt_match_seq_next,
1328 	.stop	= xt_mttg_seq_stop,
1329 	.show	= xt_match_seq_show,
1330 };
1331 
xt_match_open(struct inode * inode,struct file * file)1332 static int xt_match_open(struct inode *inode, struct file *file)
1333 {
1334 	struct nf_mttg_trav *trav;
1335 	trav = __seq_open_private(file, &xt_match_seq_ops, sizeof(*trav));
1336 	if (!trav)
1337 		return -ENOMEM;
1338 
1339 	trav->nfproto = (unsigned long)PDE_DATA(inode);
1340 	return 0;
1341 }
1342 
1343 static const struct file_operations xt_match_ops = {
1344 	.owner	 = THIS_MODULE,
1345 	.open	 = xt_match_open,
1346 	.read	 = seq_read,
1347 	.llseek	 = seq_lseek,
1348 	.release = seq_release_private,
1349 };
1350 
xt_target_seq_start(struct seq_file * seq,loff_t * pos)1351 static void *xt_target_seq_start(struct seq_file *seq, loff_t *pos)
1352 {
1353 	return xt_mttg_seq_start(seq, pos, true);
1354 }
1355 
xt_target_seq_next(struct seq_file * seq,void * v,loff_t * ppos)1356 static void *xt_target_seq_next(struct seq_file *seq, void *v, loff_t *ppos)
1357 {
1358 	return xt_mttg_seq_next(seq, v, ppos, true);
1359 }
1360 
xt_target_seq_show(struct seq_file * seq,void * v)1361 static int xt_target_seq_show(struct seq_file *seq, void *v)
1362 {
1363 	const struct nf_mttg_trav *trav = seq->private;
1364 	const struct xt_target *target;
1365 
1366 	switch (trav->class) {
1367 	case MTTG_TRAV_NFP_UNSPEC:
1368 	case MTTG_TRAV_NFP_SPEC:
1369 		if (trav->curr == trav->head)
1370 			return 0;
1371 		target = list_entry(trav->curr, struct xt_target, list);
1372 		if (*target->name)
1373 			seq_printf(seq, "%s\n", target->name);
1374 	}
1375 	return 0;
1376 }
1377 
1378 static const struct seq_operations xt_target_seq_ops = {
1379 	.start	= xt_target_seq_start,
1380 	.next	= xt_target_seq_next,
1381 	.stop	= xt_mttg_seq_stop,
1382 	.show	= xt_target_seq_show,
1383 };
1384 
xt_target_open(struct inode * inode,struct file * file)1385 static int xt_target_open(struct inode *inode, struct file *file)
1386 {
1387 	struct nf_mttg_trav *trav;
1388 	trav = __seq_open_private(file, &xt_target_seq_ops, sizeof(*trav));
1389 	if (!trav)
1390 		return -ENOMEM;
1391 
1392 	trav->nfproto = (unsigned long)PDE_DATA(inode);
1393 	return 0;
1394 }
1395 
1396 static const struct file_operations xt_target_ops = {
1397 	.owner	 = THIS_MODULE,
1398 	.open	 = xt_target_open,
1399 	.read	 = seq_read,
1400 	.llseek	 = seq_lseek,
1401 	.release = seq_release_private,
1402 };
1403 
1404 #define FORMAT_TABLES	"_tables_names"
1405 #define	FORMAT_MATCHES	"_tables_matches"
1406 #define FORMAT_TARGETS 	"_tables_targets"
1407 
1408 #endif /* CONFIG_PROC_FS */
1409 
1410 /**
1411  * xt_hook_link - set up hooks for a new table
1412  * @table:	table with metadata needed to set up hooks
1413  * @fn:		Hook function
1414  *
1415  * This function will take care of creating and registering the necessary
1416  * Netfilter hooks for XT tables.
1417  */
xt_hook_link(const struct xt_table * table,nf_hookfn * fn)1418 struct nf_hook_ops *xt_hook_link(const struct xt_table *table, nf_hookfn *fn)
1419 {
1420 	unsigned int hook_mask = table->valid_hooks;
1421 	uint8_t i, num_hooks = hweight32(hook_mask);
1422 	uint8_t hooknum;
1423 	struct nf_hook_ops *ops;
1424 	int ret;
1425 
1426 	ops = kmalloc(sizeof(*ops) * num_hooks, GFP_KERNEL);
1427 	if (ops == NULL)
1428 		return ERR_PTR(-ENOMEM);
1429 
1430 	for (i = 0, hooknum = 0; i < num_hooks && hook_mask != 0;
1431 	     hook_mask >>= 1, ++hooknum) {
1432 		if (!(hook_mask & 1))
1433 			continue;
1434 		ops[i].hook     = fn;
1435 		ops[i].pf       = table->af;
1436 		ops[i].hooknum  = hooknum;
1437 		ops[i].priority = table->priority;
1438 		++i;
1439 	}
1440 
1441 	ret = nf_register_hooks(ops, num_hooks);
1442 	if (ret < 0) {
1443 		kfree(ops);
1444 		return ERR_PTR(ret);
1445 	}
1446 
1447 	return ops;
1448 }
1449 EXPORT_SYMBOL_GPL(xt_hook_link);
1450 
1451 /**
1452  * xt_hook_unlink - remove hooks for a table
1453  * @ops:	nf_hook_ops array as returned by nf_hook_link
1454  * @hook_mask:	the very same mask that was passed to nf_hook_link
1455  */
xt_hook_unlink(const struct xt_table * table,struct nf_hook_ops * ops)1456 void xt_hook_unlink(const struct xt_table *table, struct nf_hook_ops *ops)
1457 {
1458 	nf_unregister_hooks(ops, hweight32(table->valid_hooks));
1459 	kfree(ops);
1460 }
1461 EXPORT_SYMBOL_GPL(xt_hook_unlink);
1462 
xt_proto_init(struct net * net,u_int8_t af)1463 int xt_proto_init(struct net *net, u_int8_t af)
1464 {
1465 #ifdef CONFIG_PROC_FS
1466 	char buf[XT_FUNCTION_MAXNAMELEN];
1467 	struct proc_dir_entry *proc;
1468 #endif
1469 
1470 	if (af >= ARRAY_SIZE(xt_prefix))
1471 		return -EINVAL;
1472 
1473 
1474 #ifdef CONFIG_PROC_FS
1475 	strlcpy(buf, xt_prefix[af], sizeof(buf));
1476 	strlcat(buf, FORMAT_TABLES, sizeof(buf));
1477 	proc = proc_create_data(buf, 0440, net->proc_net, &xt_table_ops,
1478 				(void *)(unsigned long)af);
1479 	if (!proc)
1480 		goto out;
1481 
1482 	strlcpy(buf, xt_prefix[af], sizeof(buf));
1483 	strlcat(buf, FORMAT_MATCHES, sizeof(buf));
1484 	proc = proc_create_data(buf, 0440, net->proc_net, &xt_match_ops,
1485 				(void *)(unsigned long)af);
1486 	if (!proc)
1487 		goto out_remove_tables;
1488 
1489 	strlcpy(buf, xt_prefix[af], sizeof(buf));
1490 	strlcat(buf, FORMAT_TARGETS, sizeof(buf));
1491 	proc = proc_create_data(buf, 0440, net->proc_net, &xt_target_ops,
1492 				(void *)(unsigned long)af);
1493 	if (!proc)
1494 		goto out_remove_matches;
1495 #endif
1496 
1497 	return 0;
1498 
1499 #ifdef CONFIG_PROC_FS
1500 out_remove_matches:
1501 	strlcpy(buf, xt_prefix[af], sizeof(buf));
1502 	strlcat(buf, FORMAT_MATCHES, sizeof(buf));
1503 	remove_proc_entry(buf, net->proc_net);
1504 
1505 out_remove_tables:
1506 	strlcpy(buf, xt_prefix[af], sizeof(buf));
1507 	strlcat(buf, FORMAT_TABLES, sizeof(buf));
1508 	remove_proc_entry(buf, net->proc_net);
1509 out:
1510 	return -1;
1511 #endif
1512 }
1513 EXPORT_SYMBOL_GPL(xt_proto_init);
1514 
xt_proto_fini(struct net * net,u_int8_t af)1515 void xt_proto_fini(struct net *net, u_int8_t af)
1516 {
1517 #ifdef CONFIG_PROC_FS
1518 	char buf[XT_FUNCTION_MAXNAMELEN];
1519 
1520 	strlcpy(buf, xt_prefix[af], sizeof(buf));
1521 	strlcat(buf, FORMAT_TABLES, sizeof(buf));
1522 	remove_proc_entry(buf, net->proc_net);
1523 
1524 	strlcpy(buf, xt_prefix[af], sizeof(buf));
1525 	strlcat(buf, FORMAT_TARGETS, sizeof(buf));
1526 	remove_proc_entry(buf, net->proc_net);
1527 
1528 	strlcpy(buf, xt_prefix[af], sizeof(buf));
1529 	strlcat(buf, FORMAT_MATCHES, sizeof(buf));
1530 	remove_proc_entry(buf, net->proc_net);
1531 #endif /*CONFIG_PROC_FS*/
1532 }
1533 EXPORT_SYMBOL_GPL(xt_proto_fini);
1534 
xt_net_init(struct net * net)1535 static int __net_init xt_net_init(struct net *net)
1536 {
1537 	int i;
1538 
1539 	for (i = 0; i < NFPROTO_NUMPROTO; i++)
1540 		INIT_LIST_HEAD(&net->xt.tables[i]);
1541 	return 0;
1542 }
1543 
1544 static struct pernet_operations xt_net_ops = {
1545 	.init = xt_net_init,
1546 };
1547 
xt_init(void)1548 static int __init xt_init(void)
1549 {
1550 	unsigned int i;
1551 	int rv;
1552 
1553 	for_each_possible_cpu(i) {
1554 		seqcount_init(&per_cpu(xt_recseq, i));
1555 	}
1556 
1557 	xt = kmalloc(sizeof(struct xt_af) * NFPROTO_NUMPROTO, GFP_KERNEL);
1558 	if (!xt)
1559 		return -ENOMEM;
1560 
1561 	for (i = 0; i < NFPROTO_NUMPROTO; i++) {
1562 		mutex_init(&xt[i].mutex);
1563 #ifdef CONFIG_COMPAT
1564 		mutex_init(&xt[i].compat_mutex);
1565 		xt[i].compat_tab = NULL;
1566 #endif
1567 		INIT_LIST_HEAD(&xt[i].target);
1568 		INIT_LIST_HEAD(&xt[i].match);
1569 	}
1570 	rv = register_pernet_subsys(&xt_net_ops);
1571 	if (rv < 0)
1572 		kfree(xt);
1573 	return rv;
1574 }
1575 
xt_fini(void)1576 static void __exit xt_fini(void)
1577 {
1578 	unregister_pernet_subsys(&xt_net_ops);
1579 	kfree(xt);
1580 }
1581 
1582 module_init(xt_init);
1583 module_exit(xt_fini);
1584 
1585