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net: Add rtnl_lock_killable()
[linux/fpc-iii.git] / net / netfilter / nfnetlink.c
blob84fc4954862d46c0fb6ca77c3842518c6cd7753e
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
32 MODULE_LICENSE("GPL");
33 MODULE_AUTHOR("Harald Welte <laforge@netfilter.org>");
34 MODULE_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
40 static struct {
41 struct mutex mutex;
42 const struct nfnetlink_subsystem __rcu *subsys;
43 } table[NFNL_SUBSYS_COUNT];
44
45 static const int nfnl_group2type[NFNLGRP_MAX+1] = {
46 [NFNLGRP_CONNTRACK_NEW] = NFNL_SUBSYS_CTNETLINK,
47 [NFNLGRP_CONNTRACK_UPDATE] = NFNL_SUBSYS_CTNETLINK,
48 [NFNLGRP_CONNTRACK_DESTROY] = NFNL_SUBSYS_CTNETLINK,
49 [NFNLGRP_CONNTRACK_EXP_NEW] = NFNL_SUBSYS_CTNETLINK_EXP,
50 [NFNLGRP_CONNTRACK_EXP_UPDATE] = NFNL_SUBSYS_CTNETLINK_EXP,
51 [NFNLGRP_CONNTRACK_EXP_DESTROY] = NFNL_SUBSYS_CTNETLINK_EXP,
52 [NFNLGRP_NFTABLES] = NFNL_SUBSYS_NFTABLES,
53 [NFNLGRP_ACCT_QUOTA] = NFNL_SUBSYS_ACCT,
54 [NFNLGRP_NFTRACE] = NFNL_SUBSYS_NFTABLES,
55 };
56
57 void nfnl_lock(__u8 subsys_id)
58 {
59 mutex_lock(&table[subsys_id].mutex);
60 }
61 EXPORT_SYMBOL_GPL(nfnl_lock);
62
63 void nfnl_unlock(__u8 subsys_id)
64 {
65 mutex_unlock(&table[subsys_id].mutex);
66 }
67 EXPORT_SYMBOL_GPL(nfnl_unlock);
68
69 #ifdef CONFIG_PROVE_LOCKING
70 bool lockdep_nfnl_is_held(u8 subsys_id)
71 {
72 return lockdep_is_held(&table[subsys_id].mutex);
73 }
74 EXPORT_SYMBOL_GPL(lockdep_nfnl_is_held);
75 #endif
76
77 int nfnetlink_subsys_register(const struct nfnetlink_subsystem *n)
78 {
79 nfnl_lock(n->subsys_id);
80 if (table[n->subsys_id].subsys) {
81 nfnl_unlock(n->subsys_id);
82 return -EBUSY;
83 }
84 rcu_assign_pointer(table[n->subsys_id].subsys, n);
85 nfnl_unlock(n->subsys_id);
86
87 return 0;
88 }
89 EXPORT_SYMBOL_GPL(nfnetlink_subsys_register);
90
91 int nfnetlink_subsys_unregister(const struct nfnetlink_subsystem *n)
92 {
93 nfnl_lock(n->subsys_id);
94 table[n->subsys_id].subsys = NULL;
95 nfnl_unlock(n->subsys_id);
96 synchronize_rcu();
97 return 0;
98 }
99 EXPORT_SYMBOL_GPL(nfnetlink_subsys_unregister);
100
101 static inline const struct nfnetlink_subsystem *nfnetlink_get_subsys(u16 type)
102 {
103 u8 subsys_id = NFNL_SUBSYS_ID(type);
104
105 if (subsys_id >= NFNL_SUBSYS_COUNT)
106 return NULL;
107
108 return rcu_dereference(table[subsys_id].subsys);
109 }
110
111 static inline const struct nfnl_callback *
112 nfnetlink_find_client(u16 type, const struct nfnetlink_subsystem *ss)
113 {
114 u8 cb_id = NFNL_MSG_TYPE(type);
115
116 if (cb_id >= ss->cb_count)
117 return NULL;
118
119 return &ss->cb[cb_id];
120 }
121
122 int nfnetlink_has_listeners(struct net *net, unsigned int group)
123 {
124 return netlink_has_listeners(net->nfnl, group);
125 }
126 EXPORT_SYMBOL_GPL(nfnetlink_has_listeners);
127
128 int nfnetlink_send(struct sk_buff *skb, struct net *net, u32 portid,
129 unsigned int group, int echo, gfp_t flags)
130 {
131 return nlmsg_notify(net->nfnl, skb, portid, group, echo, flags);
132 }
133 EXPORT_SYMBOL_GPL(nfnetlink_send);
134
135 int nfnetlink_set_err(struct net *net, u32 portid, u32 group, int error)
136 {
137 return netlink_set_err(net->nfnl, portid, group, error);
138 }
139 EXPORT_SYMBOL_GPL(nfnetlink_set_err);
140
141 int nfnetlink_unicast(struct sk_buff *skb, struct net *net, u32 portid,
142 int flags)
143 {
144 return netlink_unicast(net->nfnl, skb, portid, flags);
145 }
146 EXPORT_SYMBOL_GPL(nfnetlink_unicast);
147
148 /* Process one complete nfnetlink message. */
149 static int nfnetlink_rcv_msg(struct sk_buff *skb, struct nlmsghdr *nlh,
150 struct netlink_ext_ack *extack)
151 {
152 struct net *net = sock_net(skb->sk);
153 const struct nfnl_callback *nc;
154 const struct nfnetlink_subsystem *ss;
155 int type, err;
156
157 /* All the messages must at least contain nfgenmsg */
158 if (nlmsg_len(nlh) < sizeof(struct nfgenmsg))
159 return 0;
160
161 type = nlh->nlmsg_type;
162 replay:
163 rcu_read_lock();
164 ss = nfnetlink_get_subsys(type);
165 if (!ss) {
166 #ifdef CONFIG_MODULES
167 rcu_read_unlock();
168 request_module("nfnetlink-subsys-%d", NFNL_SUBSYS_ID(type));
169 rcu_read_lock();
170 ss = nfnetlink_get_subsys(type);
171 if (!ss)
172 #endif
173 {
174 rcu_read_unlock();
175 return -EINVAL;
176 }
177 }
178
179 nc = nfnetlink_find_client(type, ss);
180 if (!nc) {
181 rcu_read_unlock();
182 return -EINVAL;
183 }
184
185 {
186 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
187 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
188 struct nlattr *cda[ss->cb[cb_id].attr_count + 1];
189 struct nlattr *attr = (void *)nlh + min_len;
190 int attrlen = nlh->nlmsg_len - min_len;
191 __u8 subsys_id = NFNL_SUBSYS_ID(type);
192
193 err = nla_parse(cda, ss->cb[cb_id].attr_count, attr, attrlen,
194 ss->cb[cb_id].policy, extack);
195 if (err < 0) {
196 rcu_read_unlock();
197 return err;
198 }
199
200 if (nc->call_rcu) {
201 err = nc->call_rcu(net, net->nfnl, skb, nlh,
202 (const struct nlattr **)cda,
203 extack);
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 extack);
215 else
216 err = -EINVAL;
217 nfnl_unlock(subsys_id);
218 }
219 if (err == -EAGAIN)
220 goto replay;
221 return err;
222 }
223 }
224
225 struct nfnl_err {
226 struct list_head head;
227 struct nlmsghdr *nlh;
228 int err;
229 struct netlink_ext_ack extack;
230 };
231
232 static int nfnl_err_add(struct list_head *list, struct nlmsghdr *nlh, int err,
233 const struct netlink_ext_ack *extack)
234 {
235 struct nfnl_err *nfnl_err;
236
237 nfnl_err = kmalloc(sizeof(struct nfnl_err), GFP_KERNEL);
238 if (nfnl_err == NULL)
239 return -ENOMEM;
240
241 nfnl_err->nlh = nlh;
242 nfnl_err->err = err;
243 nfnl_err->extack = *extack;
244 list_add_tail(&nfnl_err->head, list);
245
246 return 0;
247 }
248
249 static void nfnl_err_del(struct nfnl_err *nfnl_err)
250 {
251 list_del(&nfnl_err->head);
252 kfree(nfnl_err);
253 }
254
255 static void nfnl_err_reset(struct list_head *err_list)
256 {
257 struct nfnl_err *nfnl_err, *next;
258
259 list_for_each_entry_safe(nfnl_err, next, err_list, head)
260 nfnl_err_del(nfnl_err);
261 }
262
263 static void nfnl_err_deliver(struct list_head *err_list, struct sk_buff *skb)
264 {
265 struct nfnl_err *nfnl_err, *next;
266
267 list_for_each_entry_safe(nfnl_err, next, err_list, head) {
268 netlink_ack(skb, nfnl_err->nlh, nfnl_err->err,
269 &nfnl_err->extack);
270 nfnl_err_del(nfnl_err);
271 }
272 }
273
274 enum {
275 NFNL_BATCH_FAILURE = (1 << 0),
276 NFNL_BATCH_DONE = (1 << 1),
277 NFNL_BATCH_REPLAY = (1 << 2),
278 };
279
280 static void nfnetlink_rcv_batch(struct sk_buff *skb, struct nlmsghdr *nlh,
281 u16 subsys_id, u32 genid)
282 {
283 struct sk_buff *oskb = skb;
284 struct net *net = sock_net(skb->sk);
285 const struct nfnetlink_subsystem *ss;
286 const struct nfnl_callback *nc;
287 struct netlink_ext_ack extack;
288 LIST_HEAD(err_list);
289 u32 status;
290 int err;
291
292 if (subsys_id >= NFNL_SUBSYS_COUNT)
293 return netlink_ack(skb, nlh, -EINVAL, NULL);
294 replay:
295 status = 0;
296
297 skb = netlink_skb_clone(oskb, GFP_KERNEL);
298 if (!skb)
299 return netlink_ack(oskb, nlh, -ENOMEM, NULL);
300
301 nfnl_lock(subsys_id);
302 ss = nfnl_dereference_protected(subsys_id);
303 if (!ss) {
304 #ifdef CONFIG_MODULES
305 nfnl_unlock(subsys_id);
306 request_module("nfnetlink-subsys-%d", subsys_id);
307 nfnl_lock(subsys_id);
308 ss = nfnl_dereference_protected(subsys_id);
309 if (!ss)
310 #endif
311 {
312 nfnl_unlock(subsys_id);
313 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
314 return kfree_skb(skb);
315 }
316 }
317
318 if (!ss->commit || !ss->abort) {
319 nfnl_unlock(subsys_id);
320 netlink_ack(oskb, nlh, -EOPNOTSUPP, NULL);
321 return kfree_skb(skb);
322 }
323
324 if (genid && ss->valid_genid && !ss->valid_genid(net, genid)) {
325 nfnl_unlock(subsys_id);
326 netlink_ack(oskb, nlh, -ERESTART, NULL);
327 return kfree_skb(skb);
328 }
329
330 while (skb->len >= nlmsg_total_size(0)) {
331 int msglen, type;
332
333 memset(&extack, 0, sizeof(extack));
334 nlh = nlmsg_hdr(skb);
335 err = 0;
336
337 if (nlh->nlmsg_len < NLMSG_HDRLEN ||
338 skb->len < nlh->nlmsg_len ||
339 nlmsg_len(nlh) < sizeof(struct nfgenmsg)) {
340 nfnl_err_reset(&err_list);
341 status |= NFNL_BATCH_FAILURE;
342 goto done;
343 }
344
345 /* Only requests are handled by the kernel */
346 if (!(nlh->nlmsg_flags & NLM_F_REQUEST)) {
347 err = -EINVAL;
348 goto ack;
349 }
350
351 type = nlh->nlmsg_type;
352 if (type == NFNL_MSG_BATCH_BEGIN) {
353 /* Malformed: Batch begin twice */
354 nfnl_err_reset(&err_list);
355 status |= NFNL_BATCH_FAILURE;
356 goto done;
357 } else if (type == NFNL_MSG_BATCH_END) {
358 status |= NFNL_BATCH_DONE;
359 goto done;
360 } else if (type < NLMSG_MIN_TYPE) {
361 err = -EINVAL;
362 goto ack;
363 }
364
365 /* We only accept a batch with messages for the same
366 * subsystem.
367 */
368 if (NFNL_SUBSYS_ID(type) != subsys_id) {
369 err = -EINVAL;
370 goto ack;
371 }
372
373 nc = nfnetlink_find_client(type, ss);
374 if (!nc) {
375 err = -EINVAL;
376 goto ack;
377 }
378
379 {
380 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
381 u8 cb_id = NFNL_MSG_TYPE(nlh->nlmsg_type);
382 struct nlattr *cda[ss->cb[cb_id].attr_count + 1];
383 struct nlattr *attr = (void *)nlh + min_len;
384 int attrlen = nlh->nlmsg_len - min_len;
385
386 err = nla_parse(cda, ss->cb[cb_id].attr_count, attr,
387 attrlen, ss->cb[cb_id].policy, NULL);
388 if (err < 0)
389 goto ack;
390
391 if (nc->call_batch) {
392 err = nc->call_batch(net, net->nfnl, skb, nlh,
393 (const struct nlattr **)cda,
394 &extack);
395 }
396
397 /* The lock was released to autoload some module, we
398 * have to abort and start from scratch using the
399 * original skb.
400 */
401 if (err == -EAGAIN) {
402 status |= NFNL_BATCH_REPLAY;
403 goto next;
404 }
405 }
406 ack:
407 if (nlh->nlmsg_flags & NLM_F_ACK || err) {
408 /* Errors are delivered once the full batch has been
409 * processed, this avoids that the same error is
410 * reported several times when replaying the batch.
411 */
412 if (nfnl_err_add(&err_list, nlh, err, &extack) < 0) {
413 /* We failed to enqueue an error, reset the
414 * list of errors and send OOM to userspace
415 * pointing to the batch header.
416 */
417 nfnl_err_reset(&err_list);
418 netlink_ack(oskb, nlmsg_hdr(oskb), -ENOMEM,
419 NULL);
420 status |= NFNL_BATCH_FAILURE;
421 goto done;
422 }
423 /* We don't stop processing the batch on errors, thus,
424 * userspace gets all the errors that the batch
425 * triggers.
426 */
427 if (err)
428 status |= NFNL_BATCH_FAILURE;
429 }
430 next:
431 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
432 if (msglen > skb->len)
433 msglen = skb->len;
434 skb_pull(skb, msglen);
435 }
436 done:
437 if (status & NFNL_BATCH_REPLAY) {
438 ss->abort(net, oskb);
439 nfnl_err_reset(&err_list);
440 nfnl_unlock(subsys_id);
441 kfree_skb(skb);
442 goto replay;
443 } else if (status == NFNL_BATCH_DONE) {
444 ss->commit(net, oskb);
445 } else {
446 ss->abort(net, oskb);
447 }
448
449 nfnl_err_deliver(&err_list, oskb);
450 nfnl_unlock(subsys_id);
451 kfree_skb(skb);
452 }
453
454 static const struct nla_policy nfnl_batch_policy[NFNL_BATCH_MAX + 1] = {
455 [NFNL_BATCH_GENID] = { .type = NLA_U32 },
456 };
457
458 static void nfnetlink_rcv_skb_batch(struct sk_buff *skb, struct nlmsghdr *nlh)
459 {
460 int min_len = nlmsg_total_size(sizeof(struct nfgenmsg));
461 struct nlattr *attr = (void *)nlh + min_len;
462 struct nlattr *cda[NFNL_BATCH_MAX + 1];
463 int attrlen = nlh->nlmsg_len - min_len;
464 struct nfgenmsg *nfgenmsg;
465 int msglen, err;
466 u32 gen_id = 0;
467 u16 res_id;
468
469 msglen = NLMSG_ALIGN(nlh->nlmsg_len);
470 if (msglen > skb->len)
471 msglen = skb->len;
472
473 if (skb->len < NLMSG_HDRLEN + sizeof(struct nfgenmsg))
474 return;
475
476 err = nla_parse(cda, NFNL_BATCH_MAX, attr, attrlen, nfnl_batch_policy,
477 NULL);
478 if (err < 0) {
479 netlink_ack(skb, nlh, err, NULL);
480 return;
481 }
482 if (cda[NFNL_BATCH_GENID])
483 gen_id = ntohl(nla_get_be32(cda[NFNL_BATCH_GENID]));
484
485 nfgenmsg = nlmsg_data(nlh);
486 skb_pull(skb, msglen);
487 /* Work around old nft using host byte order */
488 if (nfgenmsg->res_id == NFNL_SUBSYS_NFTABLES)
489 res_id = NFNL_SUBSYS_NFTABLES;
490 else
491 res_id = ntohs(nfgenmsg->res_id);
492
493 nfnetlink_rcv_batch(skb, nlh, res_id, gen_id);
494 }
495
496 static void nfnetlink_rcv(struct sk_buff *skb)
497 {
498 struct nlmsghdr *nlh = nlmsg_hdr(skb);
499
500 if (skb->len < NLMSG_HDRLEN ||
501 nlh->nlmsg_len < NLMSG_HDRLEN ||
502 skb->len < nlh->nlmsg_len)
503 return;
504
505 if (!netlink_net_capable(skb, CAP_NET_ADMIN)) {
506 netlink_ack(skb, nlh, -EPERM, NULL);
507 return;
508 }
509
510 if (nlh->nlmsg_type == NFNL_MSG_BATCH_BEGIN)
511 nfnetlink_rcv_skb_batch(skb, nlh);
512 else
513 netlink_rcv_skb(skb, nfnetlink_rcv_msg);
514 }
515
516 #ifdef CONFIG_MODULES
517 static int nfnetlink_bind(struct net *net, int group)
518 {
519 const struct nfnetlink_subsystem *ss;
520 int type;
521
522 if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
523 return 0;
524
525 type = nfnl_group2type[group];
526
527 rcu_read_lock();
528 ss = nfnetlink_get_subsys(type << 8);
529 rcu_read_unlock();
530 if (!ss)
531 request_module("nfnetlink-subsys-%d", type);
532 return 0;
533 }
534 #endif
535
536 static int __net_init nfnetlink_net_init(struct net *net)
537 {
538 struct sock *nfnl;
539 struct netlink_kernel_cfg cfg = {
540 .groups = NFNLGRP_MAX,
541 .input = nfnetlink_rcv,
542 #ifdef CONFIG_MODULES
543 .bind = nfnetlink_bind,
544 #endif
545 };
546
547 nfnl = netlink_kernel_create(net, NETLINK_NETFILTER, &cfg);
548 if (!nfnl)
549 return -ENOMEM;
550 net->nfnl_stash = nfnl;
551 rcu_assign_pointer(net->nfnl, nfnl);
552 return 0;
553 }
554
555 static void __net_exit nfnetlink_net_exit_batch(struct list_head *net_exit_list)
556 {
557 struct net *net;
558
559 list_for_each_entry(net, net_exit_list, exit_list)
560 RCU_INIT_POINTER(net->nfnl, NULL);
561 synchronize_net();
562 list_for_each_entry(net, net_exit_list, exit_list)
563 netlink_kernel_release(net->nfnl_stash);
564 }
565
566 static struct pernet_operations nfnetlink_net_ops = {
567 .init = nfnetlink_net_init,
568 .exit_batch = nfnetlink_net_exit_batch,
569 .async = true,
570 };
571
572 static int __init nfnetlink_init(void)
573 {
574 int i;
575
576 for (i = NFNLGRP_NONE + 1; i <= NFNLGRP_MAX; i++)
577 BUG_ON(nfnl_group2type[i] == NFNL_SUBSYS_NONE);
578
579 for (i=0; i<NFNL_SUBSYS_COUNT; i++)
580 mutex_init(&table[i].mutex);
581
582 return register_pernet_subsys(&nfnetlink_net_ops);
583 }
584
585 static void __exit nfnetlink_exit(void)
586 {
587 unregister_pernet_subsys(&nfnetlink_net_ops);
588 }
589 module_init(nfnetlink_init);
590 module_exit(nfnetlink_exit);
Linux with added FPC-III support