2 * x_tables core - Backend for {ip,ip6,arp}_tables
4 * Copyright (C) 2006-2006 Harald Welte <laforge@netfilter.org>
5 * Copyright (C) 2006-2012 Patrick McHardy <kaber@trash.net>
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>
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.
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>
27 #include <linux/slab.h>
28 #include <linux/audit.h>
29 #include <linux/user_namespace.h>
30 #include <net/net_namespace.h>
32 #include <linux/netfilter/x_tables.h>
33 #include <linux/netfilter_arp.h>
34 #include <linux/netfilter_ipv4/ip_tables.h>
35 #include <linux/netfilter_ipv6/ip6_tables.h>
36 #include <linux/netfilter_arp/arp_tables.h>
38 MODULE_LICENSE("GPL");
39 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
40 MODULE_DESCRIPTION("{ip,ip6,arp,eb}_tables backend module");
42 #define SMP_ALIGN(x) (((x) + SMP_CACHE_BYTES-1) & ~(SMP_CACHE_BYTES-1))
43 #define XT_PCPU_BLOCK_SIZE 4096
46 unsigned int offset; /* offset in kernel */
47 int delta; /* delta in 32bit user land */
52 struct list_head match;
53 struct list_head target;
55 struct mutex compat_mutex;
56 struct compat_delta *compat_tab;
57 unsigned int number; /* number of slots in compat_tab[] */
58 unsigned int cur; /* number of used slots in compat_tab[] */
62 static struct xt_af *xt;
64 static const char *const xt_prefix[NFPROTO_NUMPROTO] = {
65 [NFPROTO_UNSPEC] = "x",
66 [NFPROTO_IPV4] = "ip",
67 [NFPROTO_ARP] = "arp",
68 [NFPROTO_BRIDGE] = "eb",
69 [NFPROTO_IPV6] = "ip6",
72 /* Registration hooks for targets. */
73 int xt_register_target(struct xt_target *target)
75 u_int8_t af = target->family;
77 mutex_lock(&xt[af].mutex);
78 list_add(&target->list, &xt[af].target);
79 mutex_unlock(&xt[af].mutex);
82 EXPORT_SYMBOL(xt_register_target);
85 xt_unregister_target(struct xt_target *target)
87 u_int8_t af = target->family;
89 mutex_lock(&xt[af].mutex);
90 list_del(&target->list);
91 mutex_unlock(&xt[af].mutex);
93 EXPORT_SYMBOL(xt_unregister_target);
96 xt_register_targets(struct xt_target *target, unsigned int n)
101 for (i = 0; i < n; i++) {
102 err = xt_register_target(&target[i]);
110 xt_unregister_targets(target, i);
113 EXPORT_SYMBOL(xt_register_targets);
116 xt_unregister_targets(struct xt_target *target, unsigned int n)
119 xt_unregister_target(&target[n]);
121 EXPORT_SYMBOL(xt_unregister_targets);
123 int xt_register_match(struct xt_match *match)
125 u_int8_t af = match->family;
127 mutex_lock(&xt[af].mutex);
128 list_add(&match->list, &xt[af].match);
129 mutex_unlock(&xt[af].mutex);
132 EXPORT_SYMBOL(xt_register_match);
135 xt_unregister_match(struct xt_match *match)
137 u_int8_t af = match->family;
139 mutex_lock(&xt[af].mutex);
140 list_del(&match->list);
141 mutex_unlock(&xt[af].mutex);
143 EXPORT_SYMBOL(xt_unregister_match);
146 xt_register_matches(struct xt_match *match, unsigned int n)
151 for (i = 0; i < n; i++) {
152 err = xt_register_match(&match[i]);
160 xt_unregister_matches(match, i);
163 EXPORT_SYMBOL(xt_register_matches);
166 xt_unregister_matches(struct xt_match *match, unsigned int n)
169 xt_unregister_match(&match[n]);
171 EXPORT_SYMBOL(xt_unregister_matches);
175 * These are weird, but module loading must not be done with mutex
176 * held (since they will register), and we have to have a single
180 /* Find match, grabs ref. Returns ERR_PTR() on error. */
181 struct xt_match *xt_find_match(u8 af, const char *name, u8 revision)
186 mutex_lock(&xt[af].mutex);
187 list_for_each_entry(m, &xt[af].match, list) {
188 if (strcmp(m->name, name) == 0) {
189 if (m->revision == revision) {
190 if (try_module_get(m->me)) {
191 mutex_unlock(&xt[af].mutex);
195 err = -EPROTOTYPE; /* Found something. */
198 mutex_unlock(&xt[af].mutex);
200 if (af != NFPROTO_UNSPEC)
201 /* Try searching again in the family-independent list */
202 return xt_find_match(NFPROTO_UNSPEC, name, revision);
206 EXPORT_SYMBOL(xt_find_match);
209 xt_request_find_match(uint8_t nfproto, const char *name, uint8_t revision)
211 struct xt_match *match;
213 match = xt_find_match(nfproto, name, revision);
215 request_module("%st_%s", xt_prefix[nfproto], name);
216 match = xt_find_match(nfproto, name, revision);
221 EXPORT_SYMBOL_GPL(xt_request_find_match);
223 /* Find target, grabs ref. Returns ERR_PTR() on error. */
224 struct xt_target *xt_find_target(u8 af, const char *name, u8 revision)
229 mutex_lock(&xt[af].mutex);
230 list_for_each_entry(t, &xt[af].target, list) {
231 if (strcmp(t->name, name) == 0) {
232 if (t->revision == revision) {
233 if (try_module_get(t->me)) {
234 mutex_unlock(&xt[af].mutex);
238 err = -EPROTOTYPE; /* Found something. */
241 mutex_unlock(&xt[af].mutex);
243 if (af != NFPROTO_UNSPEC)
244 /* Try searching again in the family-independent list */
245 return xt_find_target(NFPROTO_UNSPEC, name, revision);
249 EXPORT_SYMBOL(xt_find_target);
251 struct xt_target *xt_request_find_target(u8 af, const char *name, u8 revision)
253 struct xt_target *target;
255 target = xt_find_target(af, name, revision);
256 if (IS_ERR(target)) {
257 request_module("%st_%s", xt_prefix[af], name);
258 target = xt_find_target(af, name, revision);
263 EXPORT_SYMBOL_GPL(xt_request_find_target);
266 static int xt_obj_to_user(u16 __user *psize, u16 size,
267 void __user *pname, const char *name,
268 u8 __user *prev, u8 rev)
270 if (put_user(size, psize))
272 if (copy_to_user(pname, name, strlen(name) + 1))
274 if (put_user(rev, prev))
280 #define XT_OBJ_TO_USER(U, K, TYPE, C_SIZE) \
281 xt_obj_to_user(&U->u.TYPE##_size, C_SIZE ? : K->u.TYPE##_size, \
282 U->u.user.name, K->u.kernel.TYPE->name, \
283 &U->u.user.revision, K->u.kernel.TYPE->revision)
285 int xt_data_to_user(void __user *dst, const void *src,
286 int usersize, int size)
288 usersize = usersize ? : size;
289 if (copy_to_user(dst, src, usersize))
291 if (usersize != size && clear_user(dst + usersize, size - usersize))
296 EXPORT_SYMBOL_GPL(xt_data_to_user);
298 #define XT_DATA_TO_USER(U, K, TYPE, C_SIZE) \
299 xt_data_to_user(U->data, K->data, \
300 K->u.kernel.TYPE->usersize, \
301 C_SIZE ? : K->u.kernel.TYPE->TYPE##size)
303 int xt_match_to_user(const struct xt_entry_match *m,
304 struct xt_entry_match __user *u)
306 return XT_OBJ_TO_USER(u, m, match, 0) ||
307 XT_DATA_TO_USER(u, m, match, 0);
309 EXPORT_SYMBOL_GPL(xt_match_to_user);
311 int xt_target_to_user(const struct xt_entry_target *t,
312 struct xt_entry_target __user *u)
314 return XT_OBJ_TO_USER(u, t, target, 0) ||
315 XT_DATA_TO_USER(u, t, target, 0);
317 EXPORT_SYMBOL_GPL(xt_target_to_user);
319 static int match_revfn(u8 af, const char *name, u8 revision, int *bestp)
321 const struct xt_match *m;
324 list_for_each_entry(m, &xt[af].match, list) {
325 if (strcmp(m->name, name) == 0) {
326 if (m->revision > *bestp)
327 *bestp = m->revision;
328 if (m->revision == revision)
333 if (af != NFPROTO_UNSPEC && !have_rev)
334 return match_revfn(NFPROTO_UNSPEC, name, revision, bestp);
339 static int target_revfn(u8 af, const char *name, u8 revision, int *bestp)
341 const struct xt_target *t;
344 list_for_each_entry(t, &xt[af].target, list) {
345 if (strcmp(t->name, name) == 0) {
346 if (t->revision > *bestp)
347 *bestp = t->revision;
348 if (t->revision == revision)
353 if (af != NFPROTO_UNSPEC && !have_rev)
354 return target_revfn(NFPROTO_UNSPEC, name, revision, bestp);
359 /* Returns true or false (if no such extension at all) */
360 int xt_find_revision(u8 af, const char *name, u8 revision, int target,
363 int have_rev, best = -1;
365 mutex_lock(&xt[af].mutex);
367 have_rev = target_revfn(af, name, revision, &best);
369 have_rev = match_revfn(af, name, revision, &best);
370 mutex_unlock(&xt[af].mutex);
372 /* Nothing at all? Return 0 to try loading module. */
380 *err = -EPROTONOSUPPORT;
383 EXPORT_SYMBOL_GPL(xt_find_revision);
386 textify_hooks(char *buf, size_t size, unsigned int mask, uint8_t nfproto)
388 static const char *const inetbr_names[] = {
389 "PREROUTING", "INPUT", "FORWARD",
390 "OUTPUT", "POSTROUTING", "BROUTING",
392 static const char *const arp_names[] = {
393 "INPUT", "FORWARD", "OUTPUT",
395 const char *const *names;
401 names = (nfproto == NFPROTO_ARP) ? arp_names : inetbr_names;
402 max = (nfproto == NFPROTO_ARP) ? ARRAY_SIZE(arp_names) :
403 ARRAY_SIZE(inetbr_names);
405 for (i = 0; i < max; ++i) {
406 if (!(mask & (1 << i)))
408 res = snprintf(p, size, "%s%s", np ? "/" : "", names[i]);
419 int xt_check_match(struct xt_mtchk_param *par,
420 unsigned int size, u_int8_t proto, bool inv_proto)
424 if (XT_ALIGN(par->match->matchsize) != size &&
425 par->match->matchsize != -1) {
427 * ebt_among is exempt from centralized matchsize checking
428 * because it uses a dynamic-size data set.
430 pr_err("%s_tables: %s.%u match: invalid size "
431 "%u (kernel) != (user) %u\n",
432 xt_prefix[par->family], par->match->name,
433 par->match->revision,
434 XT_ALIGN(par->match->matchsize), size);
437 if (par->match->table != NULL &&
438 strcmp(par->match->table, par->table) != 0) {
439 pr_err("%s_tables: %s match: only valid in %s table, not %s\n",
440 xt_prefix[par->family], par->match->name,
441 par->match->table, par->table);
444 if (par->match->hooks && (par->hook_mask & ~par->match->hooks) != 0) {
445 char used[64], allow[64];
447 pr_err("%s_tables: %s match: used from hooks %s, but only "
449 xt_prefix[par->family], par->match->name,
450 textify_hooks(used, sizeof(used), par->hook_mask,
452 textify_hooks(allow, sizeof(allow), par->match->hooks,
456 if (par->match->proto && (par->match->proto != proto || inv_proto)) {
457 pr_err("%s_tables: %s match: only valid for protocol %u\n",
458 xt_prefix[par->family], par->match->name,
462 if (par->match->checkentry != NULL) {
463 ret = par->match->checkentry(par);
467 /* Flag up potential errors. */
472 EXPORT_SYMBOL_GPL(xt_check_match);
474 /** xt_check_entry_match - check that matches end before start of target
476 * @match: beginning of xt_entry_match
477 * @target: beginning of this rules target (alleged end of matches)
478 * @alignment: alignment requirement of match structures
480 * Validates that all matches add up to the beginning of the target,
481 * and that each match covers at least the base structure size.
483 * Return: 0 on success, negative errno on failure.
485 static int xt_check_entry_match(const char *match, const char *target,
486 const size_t alignment)
488 const struct xt_entry_match *pos;
489 int length = target - match;
491 if (length == 0) /* no matches */
494 pos = (struct xt_entry_match *)match;
496 if ((unsigned long)pos % alignment)
499 if (length < (int)sizeof(struct xt_entry_match))
502 if (pos->u.match_size < sizeof(struct xt_entry_match))
505 if (pos->u.match_size > length)
508 length -= pos->u.match_size;
509 pos = ((void *)((char *)(pos) + (pos)->u.match_size));
510 } while (length > 0);
516 int xt_compat_add_offset(u_int8_t af, unsigned int offset, int delta)
518 struct xt_af *xp = &xt[af];
520 if (!xp->compat_tab) {
523 xp->compat_tab = vmalloc(sizeof(struct compat_delta) * xp->number);
529 if (xp->cur >= xp->number)
533 delta += xp->compat_tab[xp->cur - 1].delta;
534 xp->compat_tab[xp->cur].offset = offset;
535 xp->compat_tab[xp->cur].delta = delta;
539 EXPORT_SYMBOL_GPL(xt_compat_add_offset);
541 void xt_compat_flush_offsets(u_int8_t af)
543 if (xt[af].compat_tab) {
544 vfree(xt[af].compat_tab);
545 xt[af].compat_tab = NULL;
550 EXPORT_SYMBOL_GPL(xt_compat_flush_offsets);
552 int xt_compat_calc_jump(u_int8_t af, unsigned int offset)
554 struct compat_delta *tmp = xt[af].compat_tab;
555 int mid, left = 0, right = xt[af].cur - 1;
557 while (left <= right) {
558 mid = (left + right) >> 1;
559 if (offset > tmp[mid].offset)
561 else if (offset < tmp[mid].offset)
564 return mid ? tmp[mid - 1].delta : 0;
566 return left ? tmp[left - 1].delta : 0;
568 EXPORT_SYMBOL_GPL(xt_compat_calc_jump);
570 void xt_compat_init_offsets(u_int8_t af, unsigned int number)
572 xt[af].number = number;
575 EXPORT_SYMBOL(xt_compat_init_offsets);
577 int xt_compat_match_offset(const struct xt_match *match)
579 u_int16_t csize = match->compatsize ? : match->matchsize;
580 return XT_ALIGN(match->matchsize) - COMPAT_XT_ALIGN(csize);
582 EXPORT_SYMBOL_GPL(xt_compat_match_offset);
584 void xt_compat_match_from_user(struct xt_entry_match *m, void **dstptr,
587 const struct xt_match *match = m->u.kernel.match;
588 struct compat_xt_entry_match *cm = (struct compat_xt_entry_match *)m;
589 int pad, off = xt_compat_match_offset(match);
590 u_int16_t msize = cm->u.user.match_size;
591 char name[sizeof(m->u.user.name)];
594 memcpy(m, cm, sizeof(*cm));
595 if (match->compat_from_user)
596 match->compat_from_user(m->data, cm->data);
598 memcpy(m->data, cm->data, msize - sizeof(*cm));
599 pad = XT_ALIGN(match->matchsize) - match->matchsize;
601 memset(m->data + match->matchsize, 0, pad);
604 m->u.user.match_size = msize;
605 strlcpy(name, match->name, sizeof(name));
606 module_put(match->me);
607 strncpy(m->u.user.name, name, sizeof(m->u.user.name));
612 EXPORT_SYMBOL_GPL(xt_compat_match_from_user);
614 int xt_compat_match_to_user(const struct xt_entry_match *m,
615 void __user **dstptr, unsigned int *size)
617 const struct xt_match *match = m->u.kernel.match;
618 struct compat_xt_entry_match __user *cm = *dstptr;
619 int off = xt_compat_match_offset(match);
620 u_int16_t msize = m->u.user.match_size - off;
622 if (XT_OBJ_TO_USER(cm, m, match, msize))
625 if (match->compat_to_user) {
626 if (match->compat_to_user((void __user *)cm->data, m->data))
629 if (XT_DATA_TO_USER(cm, m, match, msize - sizeof(*cm)))
637 EXPORT_SYMBOL_GPL(xt_compat_match_to_user);
639 /* non-compat version may have padding after verdict */
640 struct compat_xt_standard_target {
641 struct compat_xt_entry_target t;
642 compat_uint_t verdict;
645 int xt_compat_check_entry_offsets(const void *base, const char *elems,
646 unsigned int target_offset,
647 unsigned int next_offset)
649 long size_of_base_struct = elems - (const char *)base;
650 const struct compat_xt_entry_target *t;
651 const char *e = base;
653 if (target_offset < size_of_base_struct)
656 if (target_offset + sizeof(*t) > next_offset)
659 t = (void *)(e + target_offset);
660 if (t->u.target_size < sizeof(*t))
663 if (target_offset + t->u.target_size > next_offset)
666 if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 &&
667 COMPAT_XT_ALIGN(target_offset + sizeof(struct compat_xt_standard_target)) != next_offset)
670 /* compat_xt_entry match has less strict alignment requirements,
671 * otherwise they are identical. In case of padding differences
672 * we need to add compat version of xt_check_entry_match.
674 BUILD_BUG_ON(sizeof(struct compat_xt_entry_match) != sizeof(struct xt_entry_match));
676 return xt_check_entry_match(elems, base + target_offset,
677 __alignof__(struct compat_xt_entry_match));
679 EXPORT_SYMBOL(xt_compat_check_entry_offsets);
680 #endif /* CONFIG_COMPAT */
683 * xt_check_entry_offsets - validate arp/ip/ip6t_entry
685 * @base: pointer to arp/ip/ip6t_entry
686 * @elems: pointer to first xt_entry_match, i.e. ip(6)t_entry->elems
687 * @target_offset: the arp/ip/ip6_t->target_offset
688 * @next_offset: the arp/ip/ip6_t->next_offset
690 * validates that target_offset and next_offset are sane and that all
691 * match sizes (if any) align with the target offset.
693 * This function does not validate the targets or matches themselves, it
694 * only tests that all the offsets and sizes are correct, that all
695 * match structures are aligned, and that the last structure ends where
696 * the target structure begins.
698 * Also see xt_compat_check_entry_offsets for CONFIG_COMPAT version.
700 * The arp/ip/ip6t_entry structure @base must have passed following tests:
701 * - it must point to a valid memory location
702 * - base to base + next_offset must be accessible, i.e. not exceed allocated
705 * A well-formed entry looks like this:
707 * ip(6)t_entry match [mtdata] match [mtdata] target [tgdata] ip(6)t_entry
708 * e->elems[]-----' | |
712 * target_offset---------------------------------' |
713 * next_offset---------------------------------------------------'
715 * elems[]: flexible array member at end of ip(6)/arpt_entry struct.
716 * This is where matches (if any) and the target reside.
717 * target_offset: beginning of target.
718 * next_offset: start of the next rule; also: size of this rule.
719 * Since targets have a minimum size, target_offset + minlen <= next_offset.
721 * Every match stores its size, sum of sizes must not exceed target_offset.
723 * Return: 0 on success, negative errno on failure.
725 int xt_check_entry_offsets(const void *base,
727 unsigned int target_offset,
728 unsigned int next_offset)
730 long size_of_base_struct = elems - (const char *)base;
731 const struct xt_entry_target *t;
732 const char *e = base;
734 /* target start is within the ip/ip6/arpt_entry struct */
735 if (target_offset < size_of_base_struct)
738 if (target_offset + sizeof(*t) > next_offset)
741 t = (void *)(e + target_offset);
742 if (t->u.target_size < sizeof(*t))
745 if (target_offset + t->u.target_size > next_offset)
748 if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 &&
749 XT_ALIGN(target_offset + sizeof(struct xt_standard_target)) != next_offset)
752 return xt_check_entry_match(elems, base + target_offset,
753 __alignof__(struct xt_entry_match));
755 EXPORT_SYMBOL(xt_check_entry_offsets);
758 * xt_alloc_entry_offsets - allocate array to store rule head offsets
760 * @size: number of entries
762 * Return: NULL or kmalloc'd or vmalloc'd array
764 unsigned int *xt_alloc_entry_offsets(unsigned int size)
766 return kvmalloc_array(size, sizeof(unsigned int), GFP_KERNEL | __GFP_ZERO);
769 EXPORT_SYMBOL(xt_alloc_entry_offsets);
772 * xt_find_jump_offset - check if target is a valid jump offset
774 * @offsets: array containing all valid rule start offsets of a rule blob
775 * @target: the jump target to search for
776 * @size: entries in @offset
778 bool xt_find_jump_offset(const unsigned int *offsets,
779 unsigned int target, unsigned int size)
781 int m, low = 0, hi = size;
786 if (offsets[m] > target)
788 else if (offsets[m] < target)
796 EXPORT_SYMBOL(xt_find_jump_offset);
798 int xt_check_target(struct xt_tgchk_param *par,
799 unsigned int size, u_int8_t proto, bool inv_proto)
803 if (XT_ALIGN(par->target->targetsize) != size) {
804 pr_err("%s_tables: %s.%u target: invalid size "
805 "%u (kernel) != (user) %u\n",
806 xt_prefix[par->family], par->target->name,
807 par->target->revision,
808 XT_ALIGN(par->target->targetsize), size);
811 if (par->target->table != NULL &&
812 strcmp(par->target->table, par->table) != 0) {
813 pr_err("%s_tables: %s target: only valid in %s table, not %s\n",
814 xt_prefix[par->family], par->target->name,
815 par->target->table, par->table);
818 if (par->target->hooks && (par->hook_mask & ~par->target->hooks) != 0) {
819 char used[64], allow[64];
821 pr_err("%s_tables: %s target: used from hooks %s, but only "
823 xt_prefix[par->family], par->target->name,
824 textify_hooks(used, sizeof(used), par->hook_mask,
826 textify_hooks(allow, sizeof(allow), par->target->hooks,
830 if (par->target->proto && (par->target->proto != proto || inv_proto)) {
831 pr_err("%s_tables: %s target: only valid for protocol %u\n",
832 xt_prefix[par->family], par->target->name,
836 if (par->target->checkentry != NULL) {
837 ret = par->target->checkentry(par);
841 /* Flag up potential errors. */
846 EXPORT_SYMBOL_GPL(xt_check_target);
849 * xt_copy_counters_from_user - copy counters and metadata from userspace
851 * @user: src pointer to userspace memory
852 * @len: alleged size of userspace memory
853 * @info: where to store the xt_counters_info metadata
854 * @compat: true if we setsockopt call is done by 32bit task on 64bit kernel
856 * Copies counter meta data from @user and stores it in @info.
858 * vmallocs memory to hold the counters, then copies the counter data
859 * from @user to the new memory and returns a pointer to it.
861 * If @compat is true, @info gets converted automatically to the 64bit
864 * The metadata associated with the counters is stored in @info.
866 * Return: returns pointer that caller has to test via IS_ERR().
867 * If IS_ERR is false, caller has to vfree the pointer.
869 void *xt_copy_counters_from_user(const void __user *user, unsigned int len,
870 struct xt_counters_info *info, bool compat)
877 /* structures only differ in size due to alignment */
878 struct compat_xt_counters_info compat_tmp;
880 if (len <= sizeof(compat_tmp))
881 return ERR_PTR(-EINVAL);
883 len -= sizeof(compat_tmp);
884 if (copy_from_user(&compat_tmp, user, sizeof(compat_tmp)) != 0)
885 return ERR_PTR(-EFAULT);
887 strlcpy(info->name, compat_tmp.name, sizeof(info->name));
888 info->num_counters = compat_tmp.num_counters;
889 user += sizeof(compat_tmp);
893 if (len <= sizeof(*info))
894 return ERR_PTR(-EINVAL);
896 len -= sizeof(*info);
897 if (copy_from_user(info, user, sizeof(*info)) != 0)
898 return ERR_PTR(-EFAULT);
900 info->name[sizeof(info->name) - 1] = '\0';
901 user += sizeof(*info);
904 size = sizeof(struct xt_counters);
905 size *= info->num_counters;
907 if (size != (u64)len)
908 return ERR_PTR(-EINVAL);
912 return ERR_PTR(-ENOMEM);
914 if (copy_from_user(mem, user, len) == 0)
918 return ERR_PTR(-EFAULT);
920 EXPORT_SYMBOL_GPL(xt_copy_counters_from_user);
923 int xt_compat_target_offset(const struct xt_target *target)
925 u_int16_t csize = target->compatsize ? : target->targetsize;
926 return XT_ALIGN(target->targetsize) - COMPAT_XT_ALIGN(csize);
928 EXPORT_SYMBOL_GPL(xt_compat_target_offset);
930 void xt_compat_target_from_user(struct xt_entry_target *t, void **dstptr,
933 const struct xt_target *target = t->u.kernel.target;
934 struct compat_xt_entry_target *ct = (struct compat_xt_entry_target *)t;
935 int pad, off = xt_compat_target_offset(target);
936 u_int16_t tsize = ct->u.user.target_size;
937 char name[sizeof(t->u.user.name)];
940 memcpy(t, ct, sizeof(*ct));
941 if (target->compat_from_user)
942 target->compat_from_user(t->data, ct->data);
944 memcpy(t->data, ct->data, tsize - sizeof(*ct));
945 pad = XT_ALIGN(target->targetsize) - target->targetsize;
947 memset(t->data + target->targetsize, 0, pad);
950 t->u.user.target_size = tsize;
951 strlcpy(name, target->name, sizeof(name));
952 module_put(target->me);
953 strncpy(t->u.user.name, name, sizeof(t->u.user.name));
958 EXPORT_SYMBOL_GPL(xt_compat_target_from_user);
960 int xt_compat_target_to_user(const struct xt_entry_target *t,
961 void __user **dstptr, unsigned int *size)
963 const struct xt_target *target = t->u.kernel.target;
964 struct compat_xt_entry_target __user *ct = *dstptr;
965 int off = xt_compat_target_offset(target);
966 u_int16_t tsize = t->u.user.target_size - off;
968 if (XT_OBJ_TO_USER(ct, t, target, tsize))
971 if (target->compat_to_user) {
972 if (target->compat_to_user((void __user *)ct->data, t->data))
975 if (XT_DATA_TO_USER(ct, t, target, tsize - sizeof(*ct)))
983 EXPORT_SYMBOL_GPL(xt_compat_target_to_user);
986 struct xt_table_info *xt_alloc_table_info(unsigned int size)
988 struct xt_table_info *info = NULL;
989 size_t sz = sizeof(*info) + size;
991 if (sz < sizeof(*info))
994 /* Pedantry: prevent them from hitting BUG() in vmalloc.c --RR */
995 if ((SMP_ALIGN(size) >> PAGE_SHIFT) + 2 > totalram_pages)
998 if (sz <= (PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER))
999 info = kmalloc(sz, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY);
1001 info = __vmalloc(sz, GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY,
1006 memset(info, 0, sizeof(*info));
1010 EXPORT_SYMBOL(xt_alloc_table_info);
1012 void xt_free_table_info(struct xt_table_info *info)
1016 if (info->jumpstack != NULL) {
1017 for_each_possible_cpu(cpu)
1018 kvfree(info->jumpstack[cpu]);
1019 kvfree(info->jumpstack);
1024 EXPORT_SYMBOL(xt_free_table_info);
1026 /* Find table by name, grabs mutex & ref. Returns NULL on error. */
1027 struct xt_table *xt_find_table_lock(struct net *net, u_int8_t af,
1030 struct xt_table *t, *found = NULL;
1032 mutex_lock(&xt[af].mutex);
1033 list_for_each_entry(t, &net->xt.tables[af], list)
1034 if (strcmp(t->name, name) == 0 && try_module_get(t->me))
1037 if (net == &init_net)
1040 /* Table doesn't exist in this netns, re-try init */
1041 list_for_each_entry(t, &init_net.xt.tables[af], list) {
1042 if (strcmp(t->name, name))
1044 if (!try_module_get(t->me)) {
1045 mutex_unlock(&xt[af].mutex);
1049 mutex_unlock(&xt[af].mutex);
1050 if (t->table_init(net) != 0) {
1057 mutex_lock(&xt[af].mutex);
1064 /* and once again: */
1065 list_for_each_entry(t, &net->xt.tables[af], list)
1066 if (strcmp(t->name, name) == 0)
1069 module_put(found->me);
1071 mutex_unlock(&xt[af].mutex);
1074 EXPORT_SYMBOL_GPL(xt_find_table_lock);
1076 void xt_table_unlock(struct xt_table *table)
1078 mutex_unlock(&xt[table->af].mutex);
1080 EXPORT_SYMBOL_GPL(xt_table_unlock);
1082 #ifdef CONFIG_COMPAT
1083 void xt_compat_lock(u_int8_t af)
1085 mutex_lock(&xt[af].compat_mutex);
1087 EXPORT_SYMBOL_GPL(xt_compat_lock);
1089 void xt_compat_unlock(u_int8_t af)
1091 mutex_unlock(&xt[af].compat_mutex);
1093 EXPORT_SYMBOL_GPL(xt_compat_unlock);
1096 DEFINE_PER_CPU(seqcount_t, xt_recseq);
1097 EXPORT_PER_CPU_SYMBOL_GPL(xt_recseq);
1099 struct static_key xt_tee_enabled __read_mostly;
1100 EXPORT_SYMBOL_GPL(xt_tee_enabled);
1102 static int xt_jumpstack_alloc(struct xt_table_info *i)
1107 size = sizeof(void **) * nr_cpu_ids;
1108 if (size > PAGE_SIZE)
1109 i->jumpstack = kvzalloc(size, GFP_KERNEL);
1111 i->jumpstack = kzalloc(size, GFP_KERNEL);
1112 if (i->jumpstack == NULL)
1115 /* ruleset without jumps -- no stack needed */
1116 if (i->stacksize == 0)
1119 /* Jumpstack needs to be able to record two full callchains, one
1120 * from the first rule set traversal, plus one table reentrancy
1121 * via -j TEE without clobbering the callchain that brought us to
1124 * This is done by allocating two jumpstacks per cpu, on reentry
1125 * the upper half of the stack is used.
1127 * see the jumpstack setup in ipt_do_table() for more details.
1129 size = sizeof(void *) * i->stacksize * 2u;
1130 for_each_possible_cpu(cpu) {
1131 i->jumpstack[cpu] = kvmalloc_node(size, GFP_KERNEL,
1133 if (i->jumpstack[cpu] == NULL)
1135 * Freeing will be done later on by the callers. The
1136 * chain is: xt_replace_table -> __do_replace ->
1137 * do_replace -> xt_free_table_info.
1145 struct xt_table_info *
1146 xt_replace_table(struct xt_table *table,
1147 unsigned int num_counters,
1148 struct xt_table_info *newinfo,
1151 struct xt_table_info *private;
1154 ret = xt_jumpstack_alloc(newinfo);
1160 /* Do the substitution. */
1162 private = table->private;
1164 /* Check inside lock: is the old number correct? */
1165 if (num_counters != private->number) {
1166 pr_debug("num_counters != table->private->number (%u/%u)\n",
1167 num_counters, private->number);
1173 newinfo->initial_entries = private->initial_entries;
1175 * Ensure contents of newinfo are visible before assigning to
1179 table->private = newinfo;
1182 * Even though table entries have now been swapped, other CPU's
1183 * may still be using the old entries. This is okay, because
1184 * resynchronization happens because of the locking done
1185 * during the get_counters() routine.
1190 if (audit_enabled) {
1191 struct audit_buffer *ab;
1193 ab = audit_log_start(current->audit_context, GFP_KERNEL,
1194 AUDIT_NETFILTER_CFG);
1196 audit_log_format(ab, "table=%s family=%u entries=%u",
1197 table->name, table->af,
1206 EXPORT_SYMBOL_GPL(xt_replace_table);
1208 struct xt_table *xt_register_table(struct net *net,
1209 const struct xt_table *input_table,
1210 struct xt_table_info *bootstrap,
1211 struct xt_table_info *newinfo)
1214 struct xt_table_info *private;
1215 struct xt_table *t, *table;
1217 /* Don't add one object to multiple lists. */
1218 table = kmemdup(input_table, sizeof(struct xt_table), GFP_KERNEL);
1224 mutex_lock(&xt[table->af].mutex);
1225 /* Don't autoload: we'd eat our tail... */
1226 list_for_each_entry(t, &net->xt.tables[table->af], list) {
1227 if (strcmp(t->name, table->name) == 0) {
1233 /* Simplifies replace_table code. */
1234 table->private = bootstrap;
1236 if (!xt_replace_table(table, 0, newinfo, &ret))
1239 private = table->private;
1240 pr_debug("table->private->number = %u\n", private->number);
1242 /* save number of initial entries */
1243 private->initial_entries = private->number;
1245 list_add(&table->list, &net->xt.tables[table->af]);
1246 mutex_unlock(&xt[table->af].mutex);
1250 mutex_unlock(&xt[table->af].mutex);
1253 return ERR_PTR(ret);
1255 EXPORT_SYMBOL_GPL(xt_register_table);
1257 void *xt_unregister_table(struct xt_table *table)
1259 struct xt_table_info *private;
1261 mutex_lock(&xt[table->af].mutex);
1262 private = table->private;
1263 list_del(&table->list);
1264 mutex_unlock(&xt[table->af].mutex);
1269 EXPORT_SYMBOL_GPL(xt_unregister_table);
1271 #ifdef CONFIG_PROC_FS
1272 struct xt_names_priv {
1273 struct seq_net_private p;
1276 static void *xt_table_seq_start(struct seq_file *seq, loff_t *pos)
1278 struct xt_names_priv *priv = seq->private;
1279 struct net *net = seq_file_net(seq);
1280 u_int8_t af = priv->af;
1282 mutex_lock(&xt[af].mutex);
1283 return seq_list_start(&net->xt.tables[af], *pos);
1286 static void *xt_table_seq_next(struct seq_file *seq, void *v, loff_t *pos)
1288 struct xt_names_priv *priv = seq->private;
1289 struct net *net = seq_file_net(seq);
1290 u_int8_t af = priv->af;
1292 return seq_list_next(v, &net->xt.tables[af], pos);
1295 static void xt_table_seq_stop(struct seq_file *seq, void *v)
1297 struct xt_names_priv *priv = seq->private;
1298 u_int8_t af = priv->af;
1300 mutex_unlock(&xt[af].mutex);
1303 static int xt_table_seq_show(struct seq_file *seq, void *v)
1305 struct xt_table *table = list_entry(v, struct xt_table, list);
1308 seq_printf(seq, "%s\n", table->name);
1312 static const struct seq_operations xt_table_seq_ops = {
1313 .start = xt_table_seq_start,
1314 .next = xt_table_seq_next,
1315 .stop = xt_table_seq_stop,
1316 .show = xt_table_seq_show,
1319 static int xt_table_open(struct inode *inode, struct file *file)
1322 struct xt_names_priv *priv;
1324 ret = seq_open_net(inode, file, &xt_table_seq_ops,
1325 sizeof(struct xt_names_priv));
1327 priv = ((struct seq_file *)file->private_data)->private;
1328 priv->af = (unsigned long)PDE_DATA(inode);
1333 static const struct file_operations xt_table_ops = {
1334 .owner = THIS_MODULE,
1335 .open = xt_table_open,
1337 .llseek = seq_lseek,
1338 .release = seq_release_net,
1342 * Traverse state for ip{,6}_{tables,matches} for helping crossing
1343 * the multi-AF mutexes.
1345 struct nf_mttg_trav {
1346 struct list_head *head, *curr;
1347 uint8_t class, nfproto;
1352 MTTG_TRAV_NFP_UNSPEC,
1357 static void *xt_mttg_seq_next(struct seq_file *seq, void *v, loff_t *ppos,
1360 static const uint8_t next_class[] = {
1361 [MTTG_TRAV_NFP_UNSPEC] = MTTG_TRAV_NFP_SPEC,
1362 [MTTG_TRAV_NFP_SPEC] = MTTG_TRAV_DONE,
1364 struct nf_mttg_trav *trav = seq->private;
1366 switch (trav->class) {
1367 case MTTG_TRAV_INIT:
1368 trav->class = MTTG_TRAV_NFP_UNSPEC;
1369 mutex_lock(&xt[NFPROTO_UNSPEC].mutex);
1370 trav->head = trav->curr = is_target ?
1371 &xt[NFPROTO_UNSPEC].target : &xt[NFPROTO_UNSPEC].match;
1373 case MTTG_TRAV_NFP_UNSPEC:
1374 trav->curr = trav->curr->next;
1375 if (trav->curr != trav->head)
1377 mutex_unlock(&xt[NFPROTO_UNSPEC].mutex);
1378 mutex_lock(&xt[trav->nfproto].mutex);
1379 trav->head = trav->curr = is_target ?
1380 &xt[trav->nfproto].target : &xt[trav->nfproto].match;
1381 trav->class = next_class[trav->class];
1383 case MTTG_TRAV_NFP_SPEC:
1384 trav->curr = trav->curr->next;
1385 if (trav->curr != trav->head)
1387 /* fallthru, _stop will unlock */
1397 static void *xt_mttg_seq_start(struct seq_file *seq, loff_t *pos,
1400 struct nf_mttg_trav *trav = seq->private;
1403 trav->class = MTTG_TRAV_INIT;
1404 for (j = 0; j < *pos; ++j)
1405 if (xt_mttg_seq_next(seq, NULL, NULL, is_target) == NULL)
1410 static void xt_mttg_seq_stop(struct seq_file *seq, void *v)
1412 struct nf_mttg_trav *trav = seq->private;
1414 switch (trav->class) {
1415 case MTTG_TRAV_NFP_UNSPEC:
1416 mutex_unlock(&xt[NFPROTO_UNSPEC].mutex);
1418 case MTTG_TRAV_NFP_SPEC:
1419 mutex_unlock(&xt[trav->nfproto].mutex);
1424 static void *xt_match_seq_start(struct seq_file *seq, loff_t *pos)
1426 return xt_mttg_seq_start(seq, pos, false);
1429 static void *xt_match_seq_next(struct seq_file *seq, void *v, loff_t *ppos)
1431 return xt_mttg_seq_next(seq, v, ppos, false);
1434 static int xt_match_seq_show(struct seq_file *seq, void *v)
1436 const struct nf_mttg_trav *trav = seq->private;
1437 const struct xt_match *match;
1439 switch (trav->class) {
1440 case MTTG_TRAV_NFP_UNSPEC:
1441 case MTTG_TRAV_NFP_SPEC:
1442 if (trav->curr == trav->head)
1444 match = list_entry(trav->curr, struct xt_match, list);
1446 seq_printf(seq, "%s\n", match->name);
1451 static const struct seq_operations xt_match_seq_ops = {
1452 .start = xt_match_seq_start,
1453 .next = xt_match_seq_next,
1454 .stop = xt_mttg_seq_stop,
1455 .show = xt_match_seq_show,
1458 static int xt_match_open(struct inode *inode, struct file *file)
1460 struct nf_mttg_trav *trav;
1461 trav = __seq_open_private(file, &xt_match_seq_ops, sizeof(*trav));
1465 trav->nfproto = (unsigned long)PDE_DATA(inode);
1469 static const struct file_operations xt_match_ops = {
1470 .owner = THIS_MODULE,
1471 .open = xt_match_open,
1473 .llseek = seq_lseek,
1474 .release = seq_release_private,
1477 static void *xt_target_seq_start(struct seq_file *seq, loff_t *pos)
1479 return xt_mttg_seq_start(seq, pos, true);
1482 static void *xt_target_seq_next(struct seq_file *seq, void *v, loff_t *ppos)
1484 return xt_mttg_seq_next(seq, v, ppos, true);
1487 static int xt_target_seq_show(struct seq_file *seq, void *v)
1489 const struct nf_mttg_trav *trav = seq->private;
1490 const struct xt_target *target;
1492 switch (trav->class) {
1493 case MTTG_TRAV_NFP_UNSPEC:
1494 case MTTG_TRAV_NFP_SPEC:
1495 if (trav->curr == trav->head)
1497 target = list_entry(trav->curr, struct xt_target, list);
1499 seq_printf(seq, "%s\n", target->name);
1504 static const struct seq_operations xt_target_seq_ops = {
1505 .start = xt_target_seq_start,
1506 .next = xt_target_seq_next,
1507 .stop = xt_mttg_seq_stop,
1508 .show = xt_target_seq_show,
1511 static int xt_target_open(struct inode *inode, struct file *file)
1513 struct nf_mttg_trav *trav;
1514 trav = __seq_open_private(file, &xt_target_seq_ops, sizeof(*trav));
1518 trav->nfproto = (unsigned long)PDE_DATA(inode);
1522 static const struct file_operations xt_target_ops = {
1523 .owner = THIS_MODULE,
1524 .open = xt_target_open,
1526 .llseek = seq_lseek,
1527 .release = seq_release_private,
1530 #define FORMAT_TABLES "_tables_names"
1531 #define FORMAT_MATCHES "_tables_matches"
1532 #define FORMAT_TARGETS "_tables_targets"
1534 #endif /* CONFIG_PROC_FS */
1537 * xt_hook_ops_alloc - set up hooks for a new table
1538 * @table: table with metadata needed to set up hooks
1539 * @fn: Hook function
1541 * This function will create the nf_hook_ops that the x_table needs
1542 * to hand to xt_hook_link_net().
1544 struct nf_hook_ops *
1545 xt_hook_ops_alloc(const struct xt_table *table, nf_hookfn *fn)
1547 unsigned int hook_mask = table->valid_hooks;
1548 uint8_t i, num_hooks = hweight32(hook_mask);
1550 struct nf_hook_ops *ops;
1553 return ERR_PTR(-EINVAL);
1555 ops = kcalloc(num_hooks, sizeof(*ops), GFP_KERNEL);
1557 return ERR_PTR(-ENOMEM);
1559 for (i = 0, hooknum = 0; i < num_hooks && hook_mask != 0;
1560 hook_mask >>= 1, ++hooknum) {
1561 if (!(hook_mask & 1))
1564 ops[i].pf = table->af;
1565 ops[i].hooknum = hooknum;
1566 ops[i].priority = table->priority;
1572 EXPORT_SYMBOL_GPL(xt_hook_ops_alloc);
1574 int xt_proto_init(struct net *net, u_int8_t af)
1576 #ifdef CONFIG_PROC_FS
1577 char buf[XT_FUNCTION_MAXNAMELEN];
1578 struct proc_dir_entry *proc;
1583 if (af >= ARRAY_SIZE(xt_prefix))
1587 #ifdef CONFIG_PROC_FS
1588 root_uid = make_kuid(net->user_ns, 0);
1589 root_gid = make_kgid(net->user_ns, 0);
1591 strlcpy(buf, xt_prefix[af], sizeof(buf));
1592 strlcat(buf, FORMAT_TABLES, sizeof(buf));
1593 proc = proc_create_data(buf, 0440, net->proc_net, &xt_table_ops,
1594 (void *)(unsigned long)af);
1597 if (uid_valid(root_uid) && gid_valid(root_gid))
1598 proc_set_user(proc, root_uid, root_gid);
1600 strlcpy(buf, xt_prefix[af], sizeof(buf));
1601 strlcat(buf, FORMAT_MATCHES, sizeof(buf));
1602 proc = proc_create_data(buf, 0440, net->proc_net, &xt_match_ops,
1603 (void *)(unsigned long)af);
1605 goto out_remove_tables;
1606 if (uid_valid(root_uid) && gid_valid(root_gid))
1607 proc_set_user(proc, root_uid, root_gid);
1609 strlcpy(buf, xt_prefix[af], sizeof(buf));
1610 strlcat(buf, FORMAT_TARGETS, sizeof(buf));
1611 proc = proc_create_data(buf, 0440, net->proc_net, &xt_target_ops,
1612 (void *)(unsigned long)af);
1614 goto out_remove_matches;
1615 if (uid_valid(root_uid) && gid_valid(root_gid))
1616 proc_set_user(proc, root_uid, root_gid);
1621 #ifdef CONFIG_PROC_FS
1623 strlcpy(buf, xt_prefix[af], sizeof(buf));
1624 strlcat(buf, FORMAT_MATCHES, sizeof(buf));
1625 remove_proc_entry(buf, net->proc_net);
1628 strlcpy(buf, xt_prefix[af], sizeof(buf));
1629 strlcat(buf, FORMAT_TABLES, sizeof(buf));
1630 remove_proc_entry(buf, net->proc_net);
1635 EXPORT_SYMBOL_GPL(xt_proto_init);
1637 void xt_proto_fini(struct net *net, u_int8_t af)
1639 #ifdef CONFIG_PROC_FS
1640 char buf[XT_FUNCTION_MAXNAMELEN];
1642 strlcpy(buf, xt_prefix[af], sizeof(buf));
1643 strlcat(buf, FORMAT_TABLES, sizeof(buf));
1644 remove_proc_entry(buf, net->proc_net);
1646 strlcpy(buf, xt_prefix[af], sizeof(buf));
1647 strlcat(buf, FORMAT_TARGETS, sizeof(buf));
1648 remove_proc_entry(buf, net->proc_net);
1650 strlcpy(buf, xt_prefix[af], sizeof(buf));
1651 strlcat(buf, FORMAT_MATCHES, sizeof(buf));
1652 remove_proc_entry(buf, net->proc_net);
1653 #endif /*CONFIG_PROC_FS*/
1655 EXPORT_SYMBOL_GPL(xt_proto_fini);
1658 * xt_percpu_counter_alloc - allocate x_tables rule counter
1660 * @state: pointer to xt_percpu allocation state
1661 * @counter: pointer to counter struct inside the ip(6)/arpt_entry struct
1663 * On SMP, the packet counter [ ip(6)t_entry->counters.pcnt ] will then
1664 * contain the address of the real (percpu) counter.
1666 * Rule evaluation needs to use xt_get_this_cpu_counter() helper
1667 * to fetch the real percpu counter.
1669 * To speed up allocation and improve data locality, a 4kb block is
1672 * xt_percpu_counter_alloc_state contains the base address of the
1673 * allocated page and the current sub-offset.
1675 * returns false on error.
1677 bool xt_percpu_counter_alloc(struct xt_percpu_counter_alloc_state *state,
1678 struct xt_counters *counter)
1680 BUILD_BUG_ON(XT_PCPU_BLOCK_SIZE < (sizeof(*counter) * 2));
1682 if (nr_cpu_ids <= 1)
1686 state->mem = __alloc_percpu(XT_PCPU_BLOCK_SIZE,
1687 XT_PCPU_BLOCK_SIZE);
1691 counter->pcnt = (__force unsigned long)(state->mem + state->off);
1692 state->off += sizeof(*counter);
1693 if (state->off > (XT_PCPU_BLOCK_SIZE - sizeof(*counter))) {
1699 EXPORT_SYMBOL_GPL(xt_percpu_counter_alloc);
1701 void xt_percpu_counter_free(struct xt_counters *counters)
1703 unsigned long pcnt = counters->pcnt;
1705 if (nr_cpu_ids > 1 && (pcnt & (XT_PCPU_BLOCK_SIZE - 1)) == 0)
1706 free_percpu((void __percpu *)pcnt);
1708 EXPORT_SYMBOL_GPL(xt_percpu_counter_free);
1710 static int __net_init xt_net_init(struct net *net)
1714 for (i = 0; i < NFPROTO_NUMPROTO; i++)
1715 INIT_LIST_HEAD(&net->xt.tables[i]);
1719 static struct pernet_operations xt_net_ops = {
1720 .init = xt_net_init,
1723 static int __init xt_init(void)
1728 for_each_possible_cpu(i) {
1729 seqcount_init(&per_cpu(xt_recseq, i));
1732 xt = kmalloc(sizeof(struct xt_af) * NFPROTO_NUMPROTO, GFP_KERNEL);
1736 for (i = 0; i < NFPROTO_NUMPROTO; i++) {
1737 mutex_init(&xt[i].mutex);
1738 #ifdef CONFIG_COMPAT
1739 mutex_init(&xt[i].compat_mutex);
1740 xt[i].compat_tab = NULL;
1742 INIT_LIST_HEAD(&xt[i].target);
1743 INIT_LIST_HEAD(&xt[i].match);
1745 rv = register_pernet_subsys(&xt_net_ops);
1751 static void __exit xt_fini(void)
1753 unregister_pernet_subsys(&xt_net_ops);
1757 module_init(xt_init);
1758 module_exit(xt_fini);