xref: /openbmc/linux/net/netfilter/nft_compat.c (revision c4ee0af3)
1 /*
2  * (C) 2012-2013 by Pablo Neira Ayuso <pablo@netfilter.org>
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License version 2 as
6  * published by the Free Software Foundation.
7  *
8  * This software has been sponsored by Sophos Astaro <http://www.sophos.com>
9  */
10 
11 #include <linux/kernel.h>
12 #include <linux/init.h>
13 #include <linux/module.h>
14 #include <linux/netlink.h>
15 #include <linux/netfilter.h>
16 #include <linux/netfilter/nfnetlink.h>
17 #include <linux/netfilter/nf_tables.h>
18 #include <linux/netfilter/nf_tables_compat.h>
19 #include <linux/netfilter/x_tables.h>
20 #include <linux/netfilter_ipv4/ip_tables.h>
21 #include <linux/netfilter_ipv6/ip6_tables.h>
22 #include <asm/uaccess.h> /* for set_fs */
23 #include <net/netfilter/nf_tables.h>
24 
25 union nft_entry {
26 	struct ipt_entry e4;
27 	struct ip6t_entry e6;
28 };
29 
30 static inline void
31 nft_compat_set_par(struct xt_action_param *par, void *xt, const void *xt_info)
32 {
33 	par->target	= xt;
34 	par->targinfo	= xt_info;
35 	par->hotdrop	= false;
36 }
37 
38 static void nft_target_eval(const struct nft_expr *expr,
39 			    struct nft_data data[NFT_REG_MAX + 1],
40 			    const struct nft_pktinfo *pkt)
41 {
42 	void *info = nft_expr_priv(expr);
43 	struct xt_target *target = expr->ops->data;
44 	struct sk_buff *skb = pkt->skb;
45 	int ret;
46 
47 	nft_compat_set_par((struct xt_action_param *)&pkt->xt, target, info);
48 
49 	ret = target->target(skb, &pkt->xt);
50 
51 	if (pkt->xt.hotdrop)
52 		ret = NF_DROP;
53 
54 	switch(ret) {
55 	case XT_CONTINUE:
56 		data[NFT_REG_VERDICT].verdict = NFT_CONTINUE;
57 		break;
58 	default:
59 		data[NFT_REG_VERDICT].verdict = ret;
60 		break;
61 	}
62 	return;
63 }
64 
65 static const struct nla_policy nft_target_policy[NFTA_TARGET_MAX + 1] = {
66 	[NFTA_TARGET_NAME]	= { .type = NLA_NUL_STRING },
67 	[NFTA_TARGET_REV]	= { .type = NLA_U32 },
68 	[NFTA_TARGET_INFO]	= { .type = NLA_BINARY },
69 };
70 
71 static void
72 nft_target_set_tgchk_param(struct xt_tgchk_param *par,
73 			   const struct nft_ctx *ctx,
74 			   struct xt_target *target, void *info,
75 			   union nft_entry *entry, u8 proto, bool inv)
76 {
77 	par->net	= &init_net;
78 	par->table	= ctx->table->name;
79 	switch (ctx->afi->family) {
80 	case AF_INET:
81 		entry->e4.ip.proto = proto;
82 		entry->e4.ip.invflags = inv ? IPT_INV_PROTO : 0;
83 		break;
84 	case AF_INET6:
85 		entry->e6.ipv6.proto = proto;
86 		entry->e6.ipv6.invflags = inv ? IP6T_INV_PROTO : 0;
87 		break;
88 	}
89 	par->entryinfo	= entry;
90 	par->target	= target;
91 	par->targinfo	= info;
92 	if (ctx->chain->flags & NFT_BASE_CHAIN) {
93 		const struct nft_base_chain *basechain =
94 						nft_base_chain(ctx->chain);
95 		const struct nf_hook_ops *ops = &basechain->ops;
96 
97 		par->hook_mask = 1 << ops->hooknum;
98 	}
99 	par->family	= ctx->afi->family;
100 }
101 
102 static void target_compat_from_user(struct xt_target *t, void *in, void *out)
103 {
104 #ifdef CONFIG_COMPAT
105 	if (t->compat_from_user) {
106 		int pad;
107 
108 		t->compat_from_user(out, in);
109 		pad = XT_ALIGN(t->targetsize) - t->targetsize;
110 		if (pad > 0)
111 			memset(out + t->targetsize, 0, pad);
112 	} else
113 #endif
114 		memcpy(out, in, XT_ALIGN(t->targetsize));
115 }
116 
117 static inline int nft_compat_target_offset(struct xt_target *target)
118 {
119 #ifdef CONFIG_COMPAT
120 	return xt_compat_target_offset(target);
121 #else
122 	return 0;
123 #endif
124 }
125 
126 static const struct nla_policy nft_rule_compat_policy[NFTA_RULE_COMPAT_MAX + 1] = {
127 	[NFTA_RULE_COMPAT_PROTO]	= { .type = NLA_U32 },
128 	[NFTA_RULE_COMPAT_FLAGS]	= { .type = NLA_U32 },
129 };
130 
131 static int nft_parse_compat(const struct nlattr *attr, u8 *proto, bool *inv)
132 {
133 	struct nlattr *tb[NFTA_RULE_COMPAT_MAX+1];
134 	u32 flags;
135 	int err;
136 
137 	err = nla_parse_nested(tb, NFTA_RULE_COMPAT_MAX, attr,
138 			       nft_rule_compat_policy);
139 	if (err < 0)
140 		return err;
141 
142 	if (!tb[NFTA_RULE_COMPAT_PROTO] || !tb[NFTA_RULE_COMPAT_FLAGS])
143 		return -EINVAL;
144 
145 	flags = ntohl(nla_get_be32(tb[NFTA_RULE_COMPAT_FLAGS]));
146 	if (flags & ~NFT_RULE_COMPAT_F_MASK)
147 		return -EINVAL;
148 	if (flags & NFT_RULE_COMPAT_F_INV)
149 		*inv = true;
150 
151 	*proto = ntohl(nla_get_be32(tb[NFTA_RULE_COMPAT_PROTO]));
152 	return 0;
153 }
154 
155 static int
156 nft_target_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
157 		const struct nlattr * const tb[])
158 {
159 	void *info = nft_expr_priv(expr);
160 	struct xt_target *target = expr->ops->data;
161 	struct xt_tgchk_param par;
162 	size_t size = XT_ALIGN(nla_len(tb[NFTA_TARGET_INFO]));
163 	u8 proto = 0;
164 	bool inv = false;
165 	union nft_entry e = {};
166 	int ret;
167 
168 	target_compat_from_user(target, nla_data(tb[NFTA_TARGET_INFO]), info);
169 
170 	if (ctx->nla[NFTA_RULE_COMPAT]) {
171 		ret = nft_parse_compat(ctx->nla[NFTA_RULE_COMPAT], &proto, &inv);
172 		if (ret < 0)
173 			goto err;
174 	}
175 
176 	nft_target_set_tgchk_param(&par, ctx, target, info, &e, proto, inv);
177 
178 	ret = xt_check_target(&par, size, proto, inv);
179 	if (ret < 0)
180 		goto err;
181 
182 	/* The standard target cannot be used */
183 	if (target->target == NULL) {
184 		ret = -EINVAL;
185 		goto err;
186 	}
187 
188 	return 0;
189 err:
190 	module_put(target->me);
191 	return ret;
192 }
193 
194 static void
195 nft_target_destroy(const struct nft_expr *expr)
196 {
197 	struct xt_target *target = expr->ops->data;
198 
199 	module_put(target->me);
200 }
201 
202 static int
203 target_dump_info(struct sk_buff *skb, const struct xt_target *t, const void *in)
204 {
205 	int ret;
206 
207 #ifdef CONFIG_COMPAT
208 	if (t->compat_to_user) {
209 		mm_segment_t old_fs;
210 		void *out;
211 
212 		out = kmalloc(XT_ALIGN(t->targetsize), GFP_ATOMIC);
213 		if (out == NULL)
214 			return -ENOMEM;
215 
216 		/* We want to reuse existing compat_to_user */
217 		old_fs = get_fs();
218 		set_fs(KERNEL_DS);
219 		t->compat_to_user(out, in);
220 		set_fs(old_fs);
221 		ret = nla_put(skb, NFTA_TARGET_INFO, XT_ALIGN(t->targetsize), out);
222 		kfree(out);
223 	} else
224 #endif
225 		ret = nla_put(skb, NFTA_TARGET_INFO, XT_ALIGN(t->targetsize), in);
226 
227 	return ret;
228 }
229 
230 static int nft_target_dump(struct sk_buff *skb, const struct nft_expr *expr)
231 {
232 	const struct xt_target *target = expr->ops->data;
233 	void *info = nft_expr_priv(expr);
234 
235 	if (nla_put_string(skb, NFTA_TARGET_NAME, target->name) ||
236 	    nla_put_be32(skb, NFTA_TARGET_REV, htonl(target->revision)) ||
237 	    target_dump_info(skb, target, info))
238 		goto nla_put_failure;
239 
240 	return 0;
241 
242 nla_put_failure:
243 	return -1;
244 }
245 
246 static int nft_target_validate(const struct nft_ctx *ctx,
247 			       const struct nft_expr *expr,
248 			       const struct nft_data **data)
249 {
250 	struct xt_target *target = expr->ops->data;
251 	unsigned int hook_mask = 0;
252 
253 	if (ctx->chain->flags & NFT_BASE_CHAIN) {
254 		const struct nft_base_chain *basechain =
255 						nft_base_chain(ctx->chain);
256 		const struct nf_hook_ops *ops = &basechain->ops;
257 
258 		hook_mask = 1 << ops->hooknum;
259 		if (hook_mask & target->hooks)
260 			return 0;
261 
262 		/* This target is being called from an invalid chain */
263 		return -EINVAL;
264 	}
265 	return 0;
266 }
267 
268 static void nft_match_eval(const struct nft_expr *expr,
269 			   struct nft_data data[NFT_REG_MAX + 1],
270 			   const struct nft_pktinfo *pkt)
271 {
272 	void *info = nft_expr_priv(expr);
273 	struct xt_match *match = expr->ops->data;
274 	struct sk_buff *skb = pkt->skb;
275 	bool ret;
276 
277 	nft_compat_set_par((struct xt_action_param *)&pkt->xt, match, info);
278 
279 	ret = match->match(skb, (struct xt_action_param *)&pkt->xt);
280 
281 	if (pkt->xt.hotdrop) {
282 		data[NFT_REG_VERDICT].verdict = NF_DROP;
283 		return;
284 	}
285 
286 	switch(ret) {
287 	case true:
288 		data[NFT_REG_VERDICT].verdict = NFT_CONTINUE;
289 		break;
290 	case false:
291 		data[NFT_REG_VERDICT].verdict = NFT_BREAK;
292 		break;
293 	}
294 }
295 
296 static const struct nla_policy nft_match_policy[NFTA_MATCH_MAX + 1] = {
297 	[NFTA_MATCH_NAME]	= { .type = NLA_NUL_STRING },
298 	[NFTA_MATCH_REV]	= { .type = NLA_U32 },
299 	[NFTA_MATCH_INFO]	= { .type = NLA_BINARY },
300 };
301 
302 /* struct xt_mtchk_param and xt_tgchk_param look very similar */
303 static void
304 nft_match_set_mtchk_param(struct xt_mtchk_param *par, const struct nft_ctx *ctx,
305 			  struct xt_match *match, void *info,
306 			  union nft_entry *entry, u8 proto, bool inv)
307 {
308 	par->net	= &init_net;
309 	par->table	= ctx->table->name;
310 	switch (ctx->afi->family) {
311 	case AF_INET:
312 		entry->e4.ip.proto = proto;
313 		entry->e4.ip.invflags = inv ? IPT_INV_PROTO : 0;
314 		break;
315 	case AF_INET6:
316 		entry->e6.ipv6.proto = proto;
317 		entry->e6.ipv6.invflags = inv ? IP6T_INV_PROTO : 0;
318 		break;
319 	}
320 	par->entryinfo	= entry;
321 	par->match	= match;
322 	par->matchinfo	= info;
323 	if (ctx->chain->flags & NFT_BASE_CHAIN) {
324 		const struct nft_base_chain *basechain =
325 						nft_base_chain(ctx->chain);
326 		const struct nf_hook_ops *ops = &basechain->ops;
327 
328 		par->hook_mask = 1 << ops->hooknum;
329 	}
330 	par->family	= ctx->afi->family;
331 }
332 
333 static void match_compat_from_user(struct xt_match *m, void *in, void *out)
334 {
335 #ifdef CONFIG_COMPAT
336 	if (m->compat_from_user) {
337 		int pad;
338 
339 		m->compat_from_user(out, in);
340 		pad = XT_ALIGN(m->matchsize) - m->matchsize;
341 		if (pad > 0)
342 			memset(out + m->matchsize, 0, pad);
343 	} else
344 #endif
345 		memcpy(out, in, XT_ALIGN(m->matchsize));
346 }
347 
348 static int
349 nft_match_init(const struct nft_ctx *ctx, const struct nft_expr *expr,
350 		const struct nlattr * const tb[])
351 {
352 	void *info = nft_expr_priv(expr);
353 	struct xt_match *match = expr->ops->data;
354 	struct xt_mtchk_param par;
355 	size_t size = XT_ALIGN(nla_len(tb[NFTA_MATCH_INFO]));
356 	u8 proto = 0;
357 	bool inv = false;
358 	union nft_entry e = {};
359 	int ret;
360 
361 	match_compat_from_user(match, nla_data(tb[NFTA_MATCH_INFO]), info);
362 
363 	if (ctx->nla[NFTA_RULE_COMPAT]) {
364 		ret = nft_parse_compat(ctx->nla[NFTA_RULE_COMPAT], &proto, &inv);
365 		if (ret < 0)
366 			goto err;
367 	}
368 
369 	nft_match_set_mtchk_param(&par, ctx, match, info, &e, proto, inv);
370 
371 	ret = xt_check_match(&par, size, proto, inv);
372 	if (ret < 0)
373 		goto err;
374 
375 	return 0;
376 err:
377 	module_put(match->me);
378 	return ret;
379 }
380 
381 static void
382 nft_match_destroy(const struct nft_expr *expr)
383 {
384 	struct xt_match *match = expr->ops->data;
385 
386 	module_put(match->me);
387 }
388 
389 static int
390 match_dump_info(struct sk_buff *skb, const struct xt_match *m, const void *in)
391 {
392 	int ret;
393 
394 #ifdef CONFIG_COMPAT
395 	if (m->compat_to_user) {
396 		mm_segment_t old_fs;
397 		void *out;
398 
399 		out = kmalloc(XT_ALIGN(m->matchsize), GFP_ATOMIC);
400 		if (out == NULL)
401 			return -ENOMEM;
402 
403 		/* We want to reuse existing compat_to_user */
404 		old_fs = get_fs();
405 		set_fs(KERNEL_DS);
406 		m->compat_to_user(out, in);
407 		set_fs(old_fs);
408 		ret = nla_put(skb, NFTA_MATCH_INFO, XT_ALIGN(m->matchsize), out);
409 		kfree(out);
410 	} else
411 #endif
412 		ret = nla_put(skb, NFTA_MATCH_INFO, XT_ALIGN(m->matchsize), in);
413 
414 	return ret;
415 }
416 
417 static inline int nft_compat_match_offset(struct xt_match *match)
418 {
419 #ifdef CONFIG_COMPAT
420 	return xt_compat_match_offset(match);
421 #else
422 	return 0;
423 #endif
424 }
425 
426 static int nft_match_dump(struct sk_buff *skb, const struct nft_expr *expr)
427 {
428 	void *info = nft_expr_priv(expr);
429 	struct xt_match *match = expr->ops->data;
430 
431 	if (nla_put_string(skb, NFTA_MATCH_NAME, match->name) ||
432 	    nla_put_be32(skb, NFTA_MATCH_REV, htonl(match->revision)) ||
433 	    match_dump_info(skb, match, info))
434 		goto nla_put_failure;
435 
436 	return 0;
437 
438 nla_put_failure:
439 	return -1;
440 }
441 
442 static int nft_match_validate(const struct nft_ctx *ctx,
443 			      const struct nft_expr *expr,
444 			      const struct nft_data **data)
445 {
446 	struct xt_match *match = expr->ops->data;
447 	unsigned int hook_mask = 0;
448 
449 	if (ctx->chain->flags & NFT_BASE_CHAIN) {
450 		const struct nft_base_chain *basechain =
451 						nft_base_chain(ctx->chain);
452 		const struct nf_hook_ops *ops = &basechain->ops;
453 
454 		hook_mask = 1 << ops->hooknum;
455 		if (hook_mask & match->hooks)
456 			return 0;
457 
458 		/* This match is being called from an invalid chain */
459 		return -EINVAL;
460 	}
461 	return 0;
462 }
463 
464 static int
465 nfnl_compat_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
466 		      int event, u16 family, const char *name,
467 		      int rev, int target)
468 {
469 	struct nlmsghdr *nlh;
470 	struct nfgenmsg *nfmsg;
471 	unsigned int flags = portid ? NLM_F_MULTI : 0;
472 
473 	event |= NFNL_SUBSYS_NFT_COMPAT << 8;
474 	nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
475 	if (nlh == NULL)
476 		goto nlmsg_failure;
477 
478 	nfmsg = nlmsg_data(nlh);
479 	nfmsg->nfgen_family = family;
480 	nfmsg->version = NFNETLINK_V0;
481 	nfmsg->res_id = 0;
482 
483 	if (nla_put_string(skb, NFTA_COMPAT_NAME, name) ||
484 	    nla_put_be32(skb, NFTA_COMPAT_REV, htonl(rev)) ||
485 	    nla_put_be32(skb, NFTA_COMPAT_TYPE, htonl(target)))
486 		goto nla_put_failure;
487 
488 	nlmsg_end(skb, nlh);
489 	return skb->len;
490 
491 nlmsg_failure:
492 nla_put_failure:
493 	nlmsg_cancel(skb, nlh);
494 	return -1;
495 }
496 
497 static int
498 nfnl_compat_get(struct sock *nfnl, struct sk_buff *skb,
499 		const struct nlmsghdr *nlh, const struct nlattr * const tb[])
500 {
501 	int ret = 0, target;
502 	struct nfgenmsg *nfmsg;
503 	const char *fmt;
504 	const char *name;
505 	u32 rev;
506 	struct sk_buff *skb2;
507 
508 	if (tb[NFTA_COMPAT_NAME] == NULL ||
509 	    tb[NFTA_COMPAT_REV] == NULL ||
510 	    tb[NFTA_COMPAT_TYPE] == NULL)
511 		return -EINVAL;
512 
513 	name = nla_data(tb[NFTA_COMPAT_NAME]);
514 	rev = ntohl(nla_get_be32(tb[NFTA_COMPAT_REV]));
515 	target = ntohl(nla_get_be32(tb[NFTA_COMPAT_TYPE]));
516 
517 	nfmsg = nlmsg_data(nlh);
518 
519 	switch(nfmsg->nfgen_family) {
520 	case AF_INET:
521 		fmt = "ipt_%s";
522 		break;
523 	case AF_INET6:
524 		fmt = "ip6t_%s";
525 		break;
526 	default:
527 		pr_err("nft_compat: unsupported protocol %d\n",
528 			nfmsg->nfgen_family);
529 		return -EINVAL;
530 	}
531 
532 	try_then_request_module(xt_find_revision(nfmsg->nfgen_family, name,
533 						 rev, target, &ret),
534 						 fmt, name);
535 
536 	if (ret < 0)
537 		return ret;
538 
539 	skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
540 	if (skb2 == NULL)
541 		return -ENOMEM;
542 
543 	/* include the best revision for this extension in the message */
544 	if (nfnl_compat_fill_info(skb2, NETLINK_CB(skb).portid,
545 				  nlh->nlmsg_seq,
546 				  NFNL_MSG_TYPE(nlh->nlmsg_type),
547 				  NFNL_MSG_COMPAT_GET,
548 				  nfmsg->nfgen_family,
549 				  name, ret, target) <= 0) {
550 		kfree_skb(skb2);
551 		return -ENOSPC;
552 	}
553 
554 	ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
555 				MSG_DONTWAIT);
556 	if (ret > 0)
557 		ret = 0;
558 
559 	return ret == -EAGAIN ? -ENOBUFS : ret;
560 }
561 
562 static const struct nla_policy nfnl_compat_policy_get[NFTA_COMPAT_MAX+1] = {
563 	[NFTA_COMPAT_NAME]	= { .type = NLA_NUL_STRING,
564 				    .len = NFT_COMPAT_NAME_MAX-1 },
565 	[NFTA_COMPAT_REV]	= { .type = NLA_U32 },
566 	[NFTA_COMPAT_TYPE]	= { .type = NLA_U32 },
567 };
568 
569 static const struct nfnl_callback nfnl_nft_compat_cb[NFNL_MSG_COMPAT_MAX] = {
570 	[NFNL_MSG_COMPAT_GET]		= { .call = nfnl_compat_get,
571 					    .attr_count = NFTA_COMPAT_MAX,
572 					    .policy = nfnl_compat_policy_get },
573 };
574 
575 static const struct nfnetlink_subsystem nfnl_compat_subsys = {
576 	.name		= "nft-compat",
577 	.subsys_id	= NFNL_SUBSYS_NFT_COMPAT,
578 	.cb_count	= NFNL_MSG_COMPAT_MAX,
579 	.cb		= nfnl_nft_compat_cb,
580 };
581 
582 static LIST_HEAD(nft_match_list);
583 
584 struct nft_xt {
585 	struct list_head	head;
586 	struct nft_expr_ops	ops;
587 };
588 
589 static struct nft_expr_type nft_match_type;
590 
591 static const struct nft_expr_ops *
592 nft_match_select_ops(const struct nft_ctx *ctx,
593 		     const struct nlattr * const tb[])
594 {
595 	struct nft_xt *nft_match;
596 	struct xt_match *match;
597 	char *mt_name;
598 	__u32 rev, family;
599 
600 	if (tb[NFTA_MATCH_NAME] == NULL ||
601 	    tb[NFTA_MATCH_REV] == NULL ||
602 	    tb[NFTA_MATCH_INFO] == NULL)
603 		return ERR_PTR(-EINVAL);
604 
605 	mt_name = nla_data(tb[NFTA_MATCH_NAME]);
606 	rev = ntohl(nla_get_be32(tb[NFTA_MATCH_REV]));
607 	family = ctx->afi->family;
608 
609 	/* Re-use the existing match if it's already loaded. */
610 	list_for_each_entry(nft_match, &nft_match_list, head) {
611 		struct xt_match *match = nft_match->ops.data;
612 
613 		if (strcmp(match->name, mt_name) == 0 &&
614 		    match->revision == rev && match->family == family)
615 			return &nft_match->ops;
616 	}
617 
618 	match = xt_request_find_match(family, mt_name, rev);
619 	if (IS_ERR(match))
620 		return ERR_PTR(-ENOENT);
621 
622 	/* This is the first time we use this match, allocate operations */
623 	nft_match = kzalloc(sizeof(struct nft_xt), GFP_KERNEL);
624 	if (nft_match == NULL)
625 		return ERR_PTR(-ENOMEM);
626 
627 	nft_match->ops.type = &nft_match_type;
628 	nft_match->ops.size = NFT_EXPR_SIZE(XT_ALIGN(match->matchsize) +
629 					    nft_compat_match_offset(match));
630 	nft_match->ops.eval = nft_match_eval;
631 	nft_match->ops.init = nft_match_init;
632 	nft_match->ops.destroy = nft_match_destroy;
633 	nft_match->ops.dump = nft_match_dump;
634 	nft_match->ops.validate = nft_match_validate;
635 	nft_match->ops.data = match;
636 
637 	list_add(&nft_match->head, &nft_match_list);
638 
639 	return &nft_match->ops;
640 }
641 
642 static void nft_match_release(void)
643 {
644 	struct nft_xt *nft_match, *tmp;
645 
646 	list_for_each_entry_safe(nft_match, tmp, &nft_match_list, head)
647 		kfree(nft_match);
648 }
649 
650 static struct nft_expr_type nft_match_type __read_mostly = {
651 	.name		= "match",
652 	.select_ops	= nft_match_select_ops,
653 	.policy		= nft_match_policy,
654 	.maxattr	= NFTA_MATCH_MAX,
655 	.owner		= THIS_MODULE,
656 };
657 
658 static LIST_HEAD(nft_target_list);
659 
660 static struct nft_expr_type nft_target_type;
661 
662 static const struct nft_expr_ops *
663 nft_target_select_ops(const struct nft_ctx *ctx,
664 		      const struct nlattr * const tb[])
665 {
666 	struct nft_xt *nft_target;
667 	struct xt_target *target;
668 	char *tg_name;
669 	__u32 rev, family;
670 
671 	if (tb[NFTA_TARGET_NAME] == NULL ||
672 	    tb[NFTA_TARGET_REV] == NULL ||
673 	    tb[NFTA_TARGET_INFO] == NULL)
674 		return ERR_PTR(-EINVAL);
675 
676 	tg_name = nla_data(tb[NFTA_TARGET_NAME]);
677 	rev = ntohl(nla_get_be32(tb[NFTA_TARGET_REV]));
678 	family = ctx->afi->family;
679 
680 	/* Re-use the existing target if it's already loaded. */
681 	list_for_each_entry(nft_target, &nft_match_list, head) {
682 		struct xt_target *target = nft_target->ops.data;
683 
684 		if (strcmp(target->name, tg_name) == 0 &&
685 		    target->revision == rev && target->family == family)
686 			return &nft_target->ops;
687 	}
688 
689 	target = xt_request_find_target(family, tg_name, rev);
690 	if (IS_ERR(target))
691 		return ERR_PTR(-ENOENT);
692 
693 	/* This is the first time we use this target, allocate operations */
694 	nft_target = kzalloc(sizeof(struct nft_xt), GFP_KERNEL);
695 	if (nft_target == NULL)
696 		return ERR_PTR(-ENOMEM);
697 
698 	nft_target->ops.type = &nft_target_type;
699 	nft_target->ops.size = NFT_EXPR_SIZE(XT_ALIGN(target->targetsize) +
700 					     nft_compat_target_offset(target));
701 	nft_target->ops.eval = nft_target_eval;
702 	nft_target->ops.init = nft_target_init;
703 	nft_target->ops.destroy = nft_target_destroy;
704 	nft_target->ops.dump = nft_target_dump;
705 	nft_target->ops.validate = nft_target_validate;
706 	nft_target->ops.data = target;
707 
708 	list_add(&nft_target->head, &nft_target_list);
709 
710 	return &nft_target->ops;
711 }
712 
713 static void nft_target_release(void)
714 {
715 	struct nft_xt *nft_target, *tmp;
716 
717 	list_for_each_entry_safe(nft_target, tmp, &nft_target_list, head)
718 		kfree(nft_target);
719 }
720 
721 static struct nft_expr_type nft_target_type __read_mostly = {
722 	.name		= "target",
723 	.select_ops	= nft_target_select_ops,
724 	.policy		= nft_target_policy,
725 	.maxattr	= NFTA_TARGET_MAX,
726 	.owner		= THIS_MODULE,
727 };
728 
729 static int __init nft_compat_module_init(void)
730 {
731 	int ret;
732 
733 	ret = nft_register_expr(&nft_match_type);
734 	if (ret < 0)
735 		return ret;
736 
737 	ret = nft_register_expr(&nft_target_type);
738 	if (ret < 0)
739 		goto err_match;
740 
741 	ret = nfnetlink_subsys_register(&nfnl_compat_subsys);
742 	if (ret < 0) {
743 		pr_err("nft_compat: cannot register with nfnetlink.\n");
744 		goto err_target;
745 	}
746 
747 	pr_info("nf_tables_compat: (c) 2012 Pablo Neira Ayuso <pablo@netfilter.org>\n");
748 
749 	return ret;
750 
751 err_target:
752 	nft_unregister_expr(&nft_target_type);
753 err_match:
754 	nft_unregister_expr(&nft_match_type);
755 	return ret;
756 }
757 
758 static void __exit nft_compat_module_exit(void)
759 {
760 	nfnetlink_subsys_unregister(&nfnl_compat_subsys);
761 	nft_unregister_expr(&nft_target_type);
762 	nft_unregister_expr(&nft_match_type);
763 	nft_match_release();
764 	nft_target_release();
765 }
766 
767 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_NFT_COMPAT);
768 
769 module_init(nft_compat_module_init);
770 module_exit(nft_compat_module_exit);
771 
772 MODULE_LICENSE("GPL");
773 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
774 MODULE_ALIAS_NFT_EXPR("match");
775 MODULE_ALIAS_NFT_EXPR("target");
776