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1/* Netfilter messages via netlink socket. Allows for user space
2 * protocol helpers and general trouble making from userspace.
3 *
4 * (C) 2001 by Jay Schulist <jschlst@samba.org>,
5 * (C) 2002-2005 by Harald Welte <laforge@gnumonks.org>
6 * (C) 2005-2017 by Pablo Neira Ayuso <pablo@netfilter.org>
7 *
8 * Initial netfilter messages via netlink development funded and
9 * generally made possible by Network Robots, Inc. (www.networkrobots.com)
10 *
11 * Further development of this code funded by Astaro AG (http://www.astaro.com)
12 *
13 * This software may be used and distributed according to the terms
14 * of the GNU General Public License, incorporated herein by reference.
15 */
16
17#include <linux/module.h>
18#include <linux/types.h>
19#include <linux/socket.h>
20#include <linux/kernel.h>
21#include <linux/string.h>
22#include <linux/sockios.h>
23#include <linux/net.h>
24#include <linux/skbuff.h>
25#include <linux/uaccess.h>
26#include <net/sock.h>
27#include <linux/init.h>
28
29#include <net/netlink.h>
30#include <linux/netfilter/nfnetlink.h>
31
32MODULE_LICENSE("GPL");
33MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
34MODULE_ALIAS_NET_PF_PROTO(PF_NETLINK, NETLINK_NETFILTER);
35
36#define nfnl_dereference_protected(id) \
37 rcu_dereference_protected(table[(id)].subsys, \
38 lockdep_nfnl_is_held((id)))
39
40static char __initdata nfversion[] = "0.30";
41
42static struct {
43 struct mutex mutex;
44 const struct nfnetlink_subsystem __rcu *subsys;
45} table[NFNL_SUBSYS_COUNT];
46
47static const int nfnl_group2type[NFNLGRP_MAX+1] = {
48 [NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK,
49 [NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK,
50 [NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK,
51 [NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP,
52 [NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP,
53 [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
54 [NFNLGRP_NFTABLES] = NFNL_SUBSYS_NFTABLES,
55 [NFNLGRP_ACCT_QUOTA] = NFNL_SUBSYS_ACCT,
56 [NFNLGRP_NFTRACE] = NFNL_SUBSYS_NFTABLES,
57};
58
59void nfnl_lock(__u8 subsys_id)
60{
61 mutex_lock(&table[subsys_id].mutex);
62}
63EXPORT_SYMBOL_GPL(nfnl_lock);
64
65void nfnl_unlock(__u8 subsys_id)
66{
67 mutex_unlock(&table[subsys_id].mutex);
68}
69EXPORT_SYMBOL_GPL(nfnl_unlock);
70
71#ifdef CONFIG_PROVE_LOCKING
72bool lockdep_nfnl_is_held(u8 subsys_id)
73{
74 return lockdep_is_held(&table[subsys_id].mutex);
75}
76EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held);
77#endif
78
79int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
80{
81 nfnl_lock(n->subsys_id);
82 if (table[n->subsys_id].subsys) {
83 nfnl_unlock(n->subsys_id);
84 return -EBUSY;
85 }
86 rcu_assign_pointer(table[n->subsys_id].subsys, n);
87 nfnl_unlock(n->subsys_id);
88
89 return 0;
90}
91EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
92
93int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
94{
95 nfnl_lock(n->subsys_id);
96 table[n->subsys_id].subsys = NULL;
97 nfnl_unlock(n->subsys_id);
98 synchronize_rcu();
99 return 0;
100}
101EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
102
103static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type)
104{
105 u8 subsys_id = NFNL_SUBSYS_ID(type);
106
107 if (subsys_id >= NFNL_SUBSYS_COUNT)
108 return NULL;
109
110 return rcu_dereference(table[subsys_id].subsys);
111}
112
113static inline const struct nfnl_callback *
114nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss)
115{
116 u8 cb_id = NFNL_MSG_TYPE(type);
117
118 if (cb_id >= ss->cb_count)
119 return NULL;
120
121 return &ss->cb[cb_id];
122}
123
124int nfnetlink_has_listeners(struct net *net, unsigned int group)
125{
126 return netlink_has_listeners(net->nfnl, group);
127}
128EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
129
130int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid,
131 unsigned int group, int echo, gfp_t flags)
132{
133 return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags);
134}
135EXPORT_SYMBOL_GPL(nfnetlink_send);
136
137int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
138{
139 return netlink_set_err(net->nfnl, portid, group, error);
140}
141EXPORT_SYMBOL_GPL(nfnetlink_set_err);
142
143int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid,
144 int flags)
145{
146 return netlink_unicast(net->nfnl, skb, portid, flags);
147}
148EXPORT_SYMBOL_GPL(nfnetlink_unicast);
149
150/* Process one complete nfnetlink message. */
151static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
152{
153 struct net *net = sock_net(skb->sk);
154 const struct nfnl_callback *nc;
155 const struct nfnetlink_subsystem *ss;
156 int type, err;
157
158 /* All the messages must at least contain nfgenmsg */
159 if (nlmsg_len(nlh) < sizeof(struct nfgenmsg))
160 return 0;
161
162 type = nlh->nlmsg_type;
163replay:
164 rcu_read_lock();
165 ss = nfnetlink_get_subsys(type);
166 if (!ss) {
167#ifdef CONFIG_MODULES
168 rcu_read_unlock();
169 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
170 rcu_read_lock();
171 ss = nfnetlink_get_subsys(type);
172 if (!ss)
173#endif
174 {
175 rcu_read_unlock();
176 return -EINVAL;
177 }
178 }
179
180 nc = nfnetlink_find_client(type, ss);
181 if (!nc) {
182 rcu_read_unlock();
183 return -EINVAL;
184 }
185
186 {
187 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
188 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
189 struct nlattr *cda[ss->cb[cb_id].attr_count + 1];
190 struct nlattr *attr = (void *)nlh + min_len;
191 int attrlen = nlh->nlmsg_len - min_len;
192 __u8 subsys_id = NFNL_SUBSYS_ID(type);
193
194 err = nla_parse(cda, ss->cb[cb_id].attr_count,
195 attr, attrlen, ss->cb[cb_id].policy);
196 if (err < 0) {
197 rcu_read_unlock();
198 return err;
199 }
200
201 if (nc->call_rcu) {
202 err = nc->call_rcu(net, net->nfnl, skb, nlh,
203 (const struct nlattr **)cda);
204 rcu_read_unlock();
205 } else {
206 rcu_read_unlock();
207 nfnl_lock(subsys_id);
208 if (nfnl_dereference_protected(subsys_id) != ss ||
209 nfnetlink_find_client(type, ss) != nc)
210 err = -EAGAIN;
211 else if (nc->call)
212 err = nc->call(net, net->nfnl, skb, nlh,
213 (const struct nlattr **)cda);
214 else
215 err = -EINVAL;
216 nfnl_unlock(subsys_id);
217 }
218 if (err == -EAGAIN)
219 goto replay;
220 return err;
221 }
222}
223
224struct nfnl_err {
225 struct list_head head;
226 struct nlmsghdr *nlh;
227 int err;
228};
229
230static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err)
231{
232 struct nfnl_err *nfnl_err;
233
234 nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
235 if (nfnl_err == NULL)
236 return -ENOMEM;
237
238 nfnl_err->nlh = nlh;
239 nfnl_err->err = err;
240 list_add_tail(&nfnl_err->head, list);
241
242 return 0;
243}
244
245static void nfnl_err_del(struct nfnl_err *nfnl_err)
246{
247 list_del(&nfnl_err->head);
248 kfree(nfnl_err);
249}
250
251static void nfnl_err_reset(struct list_head *err_list)
252{
253 struct nfnl_err *nfnl_err, *next;
254
255 list_for_each_entry_safe(nfnl_err, next, err_list, head)
256 nfnl_err_del(nfnl_err);
257}
258
259static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
260{
261 struct nfnl_err *nfnl_err, *next;
262
263 list_for_each_entry_safe(nfnl_err, next, err_list, head) {
264 netlink_ack(skb, nfnl_err->nlh, nfnl_err->err);
265 nfnl_err_del(nfnl_err);
266 }
267}
268
269enum {
270 NFNL_BATCH_FAILURE = (1 << 0),
271 NFNL_BATCH_DONE = (1 << 1),
272 NFNL_BATCH_REPLAY = (1 << 2),
273};
274
275static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
276 u16 subsys_id, u32 genid)
277{
278 struct sk_buff *oskb = skb;
279 struct net *net = sock_net(skb->sk);
280 const struct nfnetlink_subsystem *ss;
281 const struct nfnl_callback *nc;
282 LIST_HEAD(err_list);
283 u32 status;
284 int err;
285
286 if (subsys_id >= NFNL_SUBSYS_COUNT)
287 return netlink_ack(skb, nlh, -EINVAL);
288replay:
289 status = 0;
290
291 skb = netlink_skb_clone(oskb, GFP_KERNEL);
292 if (!skb)
293 return netlink_ack(oskb, nlh, -ENOMEM);
294
295 nfnl_lock(subsys_id);
296 ss = nfnl_dereference_protected(subsys_id);
297 if (!ss) {
298#ifdef CONFIG_MODULES
299 nfnl_unlock(subsys_id);
300 request_module("nfnetlink-subsys-%d", subsys_id);
301 nfnl_lock(subsys_id);
302 ss = nfnl_dereference_protected(subsys_id);
303 if (!ss)
304#endif
305 {
306 nfnl_unlock(subsys_id);
307 netlink_ack(oskb, nlh, -EOPNOTSUPP);
308 return kfree_skb(skb);
309 }
310 }
311
312 if (!ss->commit || !ss->abort) {
313 nfnl_unlock(subsys_id);
314 netlink_ack(oskb, nlh, -EOPNOTSUPP);
315 return kfree_skb(skb);
316 }
317
318 if (genid && ss->valid_genid && !ss->valid_genid(net, genid)) {
319 nfnl_unlock(subsys_id);
320 netlink_ack(oskb, nlh, -ERESTART);
321 return kfree_skb(skb);
322 }
323
324 while (skb->len >= nlmsg_total_size(0)) {
325 int msglen, type;
326
327 nlh = nlmsg_hdr(skb);
328 err = 0;
329
330 if (nlh->nlmsg_len < NLMSG_HDRLEN ||
331 skb->len < nlh->nlmsg_len ||
332 nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
333 nfnl_err_reset(&err_list);
334 status |= NFNL_BATCH_FAILURE;
335 goto done;
336 }
337
338 /* Only requests are handled by the kernel */
339 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
340 err = -EINVAL;
341 goto ack;
342 }
343
344 type = nlh->nlmsg_type;
345 if (type == NFNL_MSG_BATCH_BEGIN) {
346 /* Malformed: Batch begin twice */
347 nfnl_err_reset(&err_list);
348 status |= NFNL_BATCH_FAILURE;
349 goto done;
350 } else if (type == NFNL_MSG_BATCH_END) {
351 status |= NFNL_BATCH_DONE;
352 goto done;
353 } else if (type < NLMSG_MIN_TYPE) {
354 err = -EINVAL;
355 goto ack;
356 }
357
358 /* We only accept a batch with messages for the same
359 * subsystem.
360 */
361 if (NFNL_SUBSYS_ID(type) != subsys_id) {
362 err = -EINVAL;
363 goto ack;
364 }
365
366 nc = nfnetlink_find_client(type, ss);
367 if (!nc) {
368 err = -EINVAL;
369 goto ack;
370 }
371
372 {
373 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
374 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
375 struct nlattr *cda[ss->cb[cb_id].attr_count + 1];
376 struct nlattr *attr = (void *)nlh + min_len;
377 int attrlen = nlh->nlmsg_len - min_len;
378
379 err = nla_parse(cda, ss->cb[cb_id].attr_count,
380 attr, attrlen, ss->cb[cb_id].policy);
381 if (err < 0)
382 goto ack;
383
384 if (nc->call_batch) {
385 err = nc->call_batch(net, net->nfnl, skb, nlh,
386 (const struct nlattr **)cda);
387 }
388
389 /* The lock was released to autoload some module, we
390 * have to abort and start from scratch using the
391 * original skb.
392 */
393 if (err == -EAGAIN) {
394 status |= NFNL_BATCH_REPLAY;
395 goto next;
396 }
397 }
398ack:
399 if (nlh->nlmsg_flags & NLM_F_ACK || err) {
400 /* Errors are delivered once the full batch has been
401 * processed, this avoids that the same error is
402 * reported several times when replaying the batch.
403 */
404 if (nfnl_err_add(&err_list, nlh, err) < 0) {
405 /* We failed to enqueue an error, reset the
406 * list of errors and send OOM to userspace
407 * pointing to the batch header.
408 */
409 nfnl_err_reset(&err_list);
410 netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM);
411 status |= NFNL_BATCH_FAILURE;
412 goto done;
413 }
414 /* We don't stop processing the batch on errors, thus,
415 * userspace gets all the errors that the batch
416 * triggers.
417 */
418 if (err)
419 status |= NFNL_BATCH_FAILURE;
420 }
421next:
422 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
423 if (msglen > skb->len)
424 msglen = skb->len;
425 skb_pull(skb, msglen);
426 }
427done:
428 if (status & NFNL_BATCH_REPLAY) {
429 ss->abort(net, oskb);
430 nfnl_err_reset(&err_list);
431 nfnl_unlock(subsys_id);
432 kfree_skb(skb);
433 goto replay;
434 } else if (status == NFNL_BATCH_DONE) {
435 ss->commit(net, oskb);
436 } else {
437 ss->abort(net, oskb);
438 }
439
440 nfnl_err_deliver(&err_list, oskb);
441 nfnl_unlock(subsys_id);
442 kfree_skb(skb);
443}
444
445static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
446 [NFNL_BATCH_GENID] = { .type = NLA_U32 },
447};
448
449static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
450{
451 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
452 struct nlattr *attr = (void *)nlh + min_len;
453 struct nlattr *cda[NFNL_BATCH_MAX + 1];
454 int attrlen = nlh->nlmsg_len - min_len;
455 struct nfgenmsg *nfgenmsg;
456 int msglen, err;
457 u32 gen_id = 0;
458 u16 res_id;
459
460 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
461 if (msglen > skb->len)
462 msglen = skb->len;
463
464 if (nlh->nlmsg_len < NLMSG_HDRLEN ||
465 skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
466 return;
467
468 err = nla_parse(cda, NFNL_BATCH_MAX, attr, attrlen, nfnl_batch_policy);
469 if (err < 0) {
470 netlink_ack(skb, nlh, err);
471 return;
472 }
473 if (cda[NFNL_BATCH_GENID])
474 gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
475
476 nfgenmsg = nlmsg_data(nlh);
477 skb_pull(skb, msglen);
478 /* Work around old nft using host byte order */
479 if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES)
480 res_id = NFNL_SUBSYS_NFTABLES;
481 else
482 res_id = ntohs(nfgenmsg->res_id);
483
484 nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
485}
486
487static void nfnetlink_rcv(struct sk_buff *skb)
488{
489 struct nlmsghdr *nlh = nlmsg_hdr(skb);
490
491 if (nlh->nlmsg_len < NLMSG_HDRLEN ||
492 skb->len < nlh->nlmsg_len)
493 return;
494
495 if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
496 netlink_ack(skb, nlh, -EPERM);
497 return;
498 }
499
500 if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
501 nfnetlink_rcv_skb_batch(skb, nlh);
502 else
503 netlink_rcv_skb(skb, &nfnetlink_rcv_msg);
504}
505
506#ifdef CONFIG_MODULES
507static int nfnetlink_bind(struct net *net, int group)
508{
509 const struct nfnetlink_subsystem *ss;
510 int type;
511
512 if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
513 return 0;
514
515 type = nfnl_group2type[group];
516
517 rcu_read_lock();
518 ss = nfnetlink_get_subsys(type << 8);
519 rcu_read_unlock();
520 if (!ss)
521 request_module("nfnetlink-subsys-%d", type);
522 return 0;
523}
524#endif
525
526static int __net_init nfnetlink_net_init(struct net *net)
527{
528 struct sock *nfnl;
529 struct netlink_kernel_cfg cfg = {
530 .groups = NFNLGRP_MAX,
531 .input = nfnetlink_rcv,
532#ifdef CONFIG_MODULES
533 .bind = nfnetlink_bind,
534#endif
535 };
536
537 nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg);
538 if (!nfnl)
539 return -ENOMEM;
540 net->nfnl_stash = nfnl;
541 rcu_assign_pointer(net->nfnl, nfnl);
542 return 0;
543}
544
545static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
546{
547 struct net *net;
548
549 list_for_each_entry(net, net_exit_list, exit_list)
550 RCU_INIT_POINTER(net->nfnl, NULL);
551 synchronize_net();
552 list_for_each_entry(net, net_exit_list, exit_list)
553 netlink_kernel_release(net->nfnl_stash);
554}
555
556static struct pernet_operations nfnetlink_net_ops = {
557 .init = nfnetlink_net_init,
558 .exit_batch = nfnetlink_net_exit_batch,
559};
560
561static int __init nfnetlink_init(void)
562{
563 int i;
564
565 for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
566 BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
567
568 for (i=0; i<NFNL_SUBSYS_COUNT; i++)
569 mutex_init(&table[i].mutex);
570
571 pr_info("Netfilter messages via NETLINK v%s.\n", nfversion);
572 return register_pernet_subsys(&nfnetlink_net_ops);
573}
574
575static void __exit nfnetlink_exit(void)
576{
577 pr_info("Removing netfilter NETLINK layer.\n");
578 unregister_pernet_subsys(&nfnetlink_net_ops);
579}
580module_init(nfnetlink_init);
581module_exit(nfnetlink_exit);