1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * (C) 2012 Pablo Neira Ayuso <pablo@netfilter.org>
4 *
5 * This software has been sponsored by Vyatta Inc. <http://www.vyatta.com>
6 */
7 #include <linux/init.h>
8 #include <linux/module.h>
9 #include <linux/kernel.h>
10 #include <linux/skbuff.h>
11 #include <linux/netlink.h>
12 #include <linux/rculist.h>
13 #include <linux/slab.h>
14 #include <linux/types.h>
15 #include <linux/list.h>
16 #include <linux/errno.h>
17 #include <linux/capability.h>
18 #include <net/netlink.h>
19 #include <net/sock.h>
20
21 #include <net/netfilter/nf_conntrack_helper.h>
22 #include <net/netfilter/nf_conntrack_expect.h>
23 #include <net/netfilter/nf_conntrack_ecache.h>
24
25 #include <linux/netfilter/nfnetlink.h>
26 #include <linux/netfilter/nfnetlink_conntrack.h>
27 #include <linux/netfilter/nfnetlink_cthelper.h>
28
29 MODULE_LICENSE("GPL");
30 MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
31 MODULE_DESCRIPTION("nfnl_cthelper: User-space connection tracking helpers");
32
33 struct nfnl_cthelper {
34 struct list_head list;
35 struct nf_conntrack_helper helper;
36 };
37
38 static LIST_HEAD(nfnl_cthelper_list);
39
40 static int
nfnl_userspace_cthelper(struct sk_buff * skb,unsigned int protoff,struct nf_conn * ct,enum ip_conntrack_info ctinfo)41 nfnl_userspace_cthelper(struct sk_buff *skb, unsigned int protoff,
42 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
43 {
44 const struct nf_conn_help *help;
45 struct nf_conntrack_helper *helper;
46
47 help = nfct_help(ct);
48 if (help == NULL)
49 return NF_DROP;
50
51 /* rcu_read_lock()ed by nf_hook_thresh */
52 helper = rcu_dereference(help->helper);
53 if (helper == NULL)
54 return NF_DROP;
55
56 /* This is a user-space helper not yet configured, skip. */
57 if ((helper->flags &
58 (NF_CT_HELPER_F_USERSPACE | NF_CT_HELPER_F_CONFIGURED)) ==
59 NF_CT_HELPER_F_USERSPACE)
60 return NF_ACCEPT;
61
62 /* If the user-space helper is not available, don't block traffic. */
63 return NF_QUEUE_NR(helper->queue_num) | NF_VERDICT_FLAG_QUEUE_BYPASS;
64 }
65
66 static const struct nla_policy nfnl_cthelper_tuple_pol[NFCTH_TUPLE_MAX+1] = {
67 [NFCTH_TUPLE_L3PROTONUM] = { .type = NLA_U16, },
68 [NFCTH_TUPLE_L4PROTONUM] = { .type = NLA_U8, },
69 };
70
71 static int
nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple * tuple,const struct nlattr * attr)72 nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple *tuple,
73 const struct nlattr *attr)
74 {
75 int err;
76 struct nlattr *tb[NFCTH_TUPLE_MAX+1];
77
78 err = nla_parse_nested_deprecated(tb, NFCTH_TUPLE_MAX, attr,
79 nfnl_cthelper_tuple_pol, NULL);
80 if (err < 0)
81 return err;
82
83 if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM])
84 return -EINVAL;
85
86 /* Not all fields are initialized so first zero the tuple */
87 memset(tuple, 0, sizeof(struct nf_conntrack_tuple));
88
89 tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
90 tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
91
92 return 0;
93 }
94
95 static int
nfnl_cthelper_from_nlattr(struct nlattr * attr,struct nf_conn * ct)96 nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
97 {
98 struct nf_conn_help *help = nfct_help(ct);
99 const struct nf_conntrack_helper *helper;
100
101 if (attr == NULL)
102 return -EINVAL;
103
104 helper = rcu_dereference(help->helper);
105 if (!helper || helper->data_len == 0)
106 return -EINVAL;
107
108 nla_memcpy(help->data, attr, sizeof(help->data));
109 return 0;
110 }
111
112 static int
nfnl_cthelper_to_nlattr(struct sk_buff * skb,const struct nf_conn * ct)113 nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
114 {
115 const struct nf_conn_help *help = nfct_help(ct);
116 const struct nf_conntrack_helper *helper;
117
118 helper = rcu_dereference(help->helper);
119 if (helper && helper->data_len &&
120 nla_put(skb, CTA_HELP_INFO, helper->data_len, &help->data))
121 goto nla_put_failure;
122
123 return 0;
124
125 nla_put_failure:
126 return -ENOSPC;
127 }
128
129 static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
130 [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
131 .len = NF_CT_HELPER_NAME_LEN-1 },
132 [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
133 [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
134 };
135
136 static int
nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy * expect_policy,const struct nlattr * attr)137 nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
138 const struct nlattr *attr)
139 {
140 int err;
141 struct nlattr *tb[NFCTH_POLICY_MAX+1];
142
143 err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_MAX, attr,
144 nfnl_cthelper_expect_pol, NULL);
145 if (err < 0)
146 return err;
147
148 if (!tb[NFCTH_POLICY_NAME] ||
149 !tb[NFCTH_POLICY_EXPECT_MAX] ||
150 !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
151 return -EINVAL;
152
153 nla_strscpy(expect_policy->name,
154 tb[NFCTH_POLICY_NAME], NF_CT_HELPER_NAME_LEN);
155 expect_policy->max_expected =
156 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
157 if (expect_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
158 return -EINVAL;
159
160 expect_policy->timeout =
161 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
162
163 return 0;
164 }
165
166 static const struct nla_policy
167 nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
168 [NFCTH_POLICY_SET_NUM] = NLA_POLICY_MAX(NLA_BE32, NF_CT_MAX_EXPECT_CLASSES),
169 };
170
171 static int
nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper * helper,const struct nlattr * attr)172 nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
173 const struct nlattr *attr)
174 {
175 int i, ret;
176 struct nf_conntrack_expect_policy *expect_policy;
177 struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
178 unsigned int class_max;
179
180 ret = nla_parse_nested_deprecated(tb, NFCTH_POLICY_SET_MAX, attr,
181 nfnl_cthelper_expect_policy_set,
182 NULL);
183 if (ret < 0)
184 return ret;
185
186 if (!tb[NFCTH_POLICY_SET_NUM])
187 return -EINVAL;
188
189 class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
190 if (class_max == 0)
191 return -EINVAL;
192 if (class_max > NF_CT_MAX_EXPECT_CLASSES)
193 return -EOVERFLOW;
194
195 expect_policy = kzalloc_objs(struct nf_conntrack_expect_policy,
196 class_max);
197 if (expect_policy == NULL)
198 return -ENOMEM;
199
200 for (i = 0; i < class_max; i++) {
201 if (!tb[NFCTH_POLICY_SET+i])
202 goto err;
203
204 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
205 tb[NFCTH_POLICY_SET+i]);
206 if (ret < 0)
207 goto err;
208 }
209
210 helper->expect_class_max = class_max - 1;
211 helper->expect_policy = expect_policy;
212 return 0;
213 err:
214 kfree(expect_policy);
215 return -EINVAL;
216 }
217
218 static int
nfnl_cthelper_create(const struct nlattr * const tb[],struct nf_conntrack_tuple * tuple)219 nfnl_cthelper_create(const struct nlattr * const tb[],
220 struct nf_conntrack_tuple *tuple)
221 {
222 struct nf_conntrack_helper *helper;
223 struct nfnl_cthelper *nfcth;
224 unsigned int size;
225 int ret;
226
227 if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
228 return -EINVAL;
229
230 nfcth = kzalloc_obj(*nfcth);
231 if (nfcth == NULL)
232 return -ENOMEM;
233 helper = &nfcth->helper;
234
235 ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
236 if (ret < 0)
237 goto err1;
238
239 nla_strscpy(helper->name,
240 tb[NFCTH_NAME], NF_CT_HELPER_NAME_LEN);
241 size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
242 if (size > sizeof_field(struct nf_conn_help, data)) {
243 ret = -ENOMEM;
244 goto err2;
245 }
246 helper->data_len = size;
247
248 helper->flags |= NF_CT_HELPER_F_USERSPACE;
249 memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
250
251 helper->me = THIS_MODULE;
252 helper->help = nfnl_userspace_cthelper;
253 helper->from_nlattr = nfnl_cthelper_from_nlattr;
254 helper->to_nlattr = nfnl_cthelper_to_nlattr;
255
256 /* Default to queue number zero, this can be updated at any time. */
257 if (tb[NFCTH_QUEUE_NUM])
258 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
259
260 if (tb[NFCTH_STATUS]) {
261 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
262
263 switch(status) {
264 case NFCT_HELPER_STATUS_ENABLED:
265 helper->flags |= NF_CT_HELPER_F_CONFIGURED;
266 break;
267 case NFCT_HELPER_STATUS_DISABLED:
268 helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
269 break;
270 }
271 }
272
273 ret = nf_conntrack_helper_register(helper);
274 if (ret < 0)
275 goto err2;
276
277 list_add_tail(&nfcth->list, &nfnl_cthelper_list);
278 return 0;
279 err2:
280 kfree(helper->expect_policy);
281 err1:
282 kfree(nfcth);
283 return ret;
284 }
285
286 static int
nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy * policy,struct nf_conntrack_expect_policy * new_policy,const struct nlattr * attr)287 nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
288 struct nf_conntrack_expect_policy *new_policy,
289 const struct nlattr *attr)
290 {
291 struct nlattr *tb[NFCTH_POLICY_MAX + 1];
292 int err;
293
294 err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_MAX, attr,
295 nfnl_cthelper_expect_pol, NULL);
296 if (err < 0)
297 return err;
298
299 if (!tb[NFCTH_POLICY_NAME] ||
300 !tb[NFCTH_POLICY_EXPECT_MAX] ||
301 !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
302 return -EINVAL;
303
304 if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
305 return -EBUSY;
306
307 new_policy->max_expected =
308 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
309 if (new_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
310 return -EINVAL;
311
312 new_policy->timeout =
313 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
314
315 return 0;
316 }
317
nfnl_cthelper_update_policy_all(struct nlattr * tb[],struct nf_conntrack_helper * helper)318 static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
319 struct nf_conntrack_helper *helper)
320 {
321 struct nf_conntrack_expect_policy *new_policy;
322 struct nf_conntrack_expect_policy *policy;
323 int i, ret = 0;
324
325 new_policy = kmalloc_objs(*new_policy, helper->expect_class_max + 1);
326 if (!new_policy)
327 return -ENOMEM;
328
329 /* Check first that all policy attributes are well-formed, so we don't
330 * leave things in inconsistent state on errors.
331 */
332 for (i = 0; i < helper->expect_class_max + 1; i++) {
333
334 if (!tb[NFCTH_POLICY_SET + i]) {
335 ret = -EINVAL;
336 goto err;
337 }
338
339 ret = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
340 &new_policy[i],
341 tb[NFCTH_POLICY_SET + i]);
342 if (ret < 0)
343 goto err;
344 }
345 /* Now we can safely update them. */
346 for (i = 0; i < helper->expect_class_max + 1; i++) {
347 policy = (struct nf_conntrack_expect_policy *)
348 &helper->expect_policy[i];
349 policy->max_expected = new_policy->max_expected;
350 policy->timeout = new_policy->timeout;
351 }
352
353 err:
354 kfree(new_policy);
355 return ret;
356 }
357
nfnl_cthelper_update_policy(struct nf_conntrack_helper * helper,const struct nlattr * attr)358 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
359 const struct nlattr *attr)
360 {
361 struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
362 unsigned int class_max;
363 int err;
364
365 err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_SET_MAX, attr,
366 nfnl_cthelper_expect_policy_set,
367 NULL);
368 if (err < 0)
369 return err;
370
371 if (!tb[NFCTH_POLICY_SET_NUM])
372 return -EINVAL;
373
374 class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
375 if (helper->expect_class_max + 1 != class_max)
376 return -EBUSY;
377
378 return nfnl_cthelper_update_policy_all(tb, helper);
379 }
380
381 static int
nfnl_cthelper_update(const struct nlattr * const tb[],struct nf_conntrack_helper * helper)382 nfnl_cthelper_update(const struct nlattr * const tb[],
383 struct nf_conntrack_helper *helper)
384 {
385 u32 size;
386 int ret;
387
388 if (tb[NFCTH_PRIV_DATA_LEN]) {
389 size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
390 if (size != helper->data_len)
391 return -EBUSY;
392 }
393
394 if (tb[NFCTH_POLICY]) {
395 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
396 if (ret < 0)
397 return ret;
398 }
399 if (tb[NFCTH_QUEUE_NUM])
400 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
401
402 if (tb[NFCTH_STATUS]) {
403 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
404
405 switch(status) {
406 case NFCT_HELPER_STATUS_ENABLED:
407 helper->flags |= NF_CT_HELPER_F_CONFIGURED;
408 break;
409 case NFCT_HELPER_STATUS_DISABLED:
410 helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
411 break;
412 }
413 }
414 return 0;
415 }
416
nfnl_cthelper_new(struct sk_buff * skb,const struct nfnl_info * info,const struct nlattr * const tb[])417 static int nfnl_cthelper_new(struct sk_buff *skb, const struct nfnl_info *info,
418 const struct nlattr * const tb[])
419 {
420 const char *helper_name;
421 struct nf_conntrack_helper *cur, *helper = NULL;
422 struct nf_conntrack_tuple tuple;
423 struct nfnl_cthelper *nlcth;
424 int ret = 0;
425
426 if (!capable(CAP_NET_ADMIN))
427 return -EPERM;
428
429 if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
430 return -EINVAL;
431
432 helper_name = nla_data(tb[NFCTH_NAME]);
433
434 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
435 if (ret < 0)
436 return ret;
437
438 list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
439 cur = &nlcth->helper;
440
441 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
442 continue;
443
444 if ((tuple.src.l3num != cur->tuple.src.l3num ||
445 tuple.dst.protonum != cur->tuple.dst.protonum))
446 continue;
447
448 if (info->nlh->nlmsg_flags & NLM_F_EXCL)
449 return -EEXIST;
450
451 helper = cur;
452 break;
453 }
454
455 if (helper == NULL)
456 ret = nfnl_cthelper_create(tb, &tuple);
457 else
458 ret = nfnl_cthelper_update(tb, helper);
459
460 return ret;
461 }
462
463 static int
nfnl_cthelper_dump_tuple(struct sk_buff * skb,struct nf_conntrack_helper * helper)464 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
465 struct nf_conntrack_helper *helper)
466 {
467 struct nlattr *nest_parms;
468
469 nest_parms = nla_nest_start(skb, NFCTH_TUPLE);
470 if (nest_parms == NULL)
471 goto nla_put_failure;
472
473 if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
474 htons(helper->tuple.src.l3num)))
475 goto nla_put_failure;
476
477 if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
478 goto nla_put_failure;
479
480 nla_nest_end(skb, nest_parms);
481 return 0;
482
483 nla_put_failure:
484 return -1;
485 }
486
487 static int
nfnl_cthelper_dump_policy(struct sk_buff * skb,struct nf_conntrack_helper * helper)488 nfnl_cthelper_dump_policy(struct sk_buff *skb,
489 struct nf_conntrack_helper *helper)
490 {
491 int i;
492 struct nlattr *nest_parms1, *nest_parms2;
493
494 nest_parms1 = nla_nest_start(skb, NFCTH_POLICY);
495 if (nest_parms1 == NULL)
496 goto nla_put_failure;
497
498 if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
499 htonl(helper->expect_class_max + 1)))
500 goto nla_put_failure;
501
502 for (i = 0; i < helper->expect_class_max + 1; i++) {
503 nest_parms2 = nla_nest_start(skb, (NFCTH_POLICY_SET + i));
504 if (nest_parms2 == NULL)
505 goto nla_put_failure;
506
507 if (nla_put_string(skb, NFCTH_POLICY_NAME,
508 helper->expect_policy[i].name))
509 goto nla_put_failure;
510
511 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
512 htonl(helper->expect_policy[i].max_expected)))
513 goto nla_put_failure;
514
515 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
516 htonl(helper->expect_policy[i].timeout)))
517 goto nla_put_failure;
518
519 nla_nest_end(skb, nest_parms2);
520 }
521 nla_nest_end(skb, nest_parms1);
522 return 0;
523
524 nla_put_failure:
525 return -1;
526 }
527
528 static int
nfnl_cthelper_fill_info(struct sk_buff * skb,u32 portid,u32 seq,u32 type,int event,struct nf_conntrack_helper * helper)529 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
530 int event, struct nf_conntrack_helper *helper)
531 {
532 struct nlmsghdr *nlh;
533 unsigned int flags = portid ? NLM_F_MULTI : 0;
534 int status;
535
536 event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, event);
537 nlh = nfnl_msg_put(skb, portid, seq, event, flags, AF_UNSPEC,
538 NFNETLINK_V0, 0);
539 if (!nlh)
540 goto nlmsg_failure;
541
542 if (nla_put_string(skb, NFCTH_NAME, helper->name))
543 goto nla_put_failure;
544
545 if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
546 goto nla_put_failure;
547
548 if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
549 goto nla_put_failure;
550
551 if (nfnl_cthelper_dump_policy(skb, helper) < 0)
552 goto nla_put_failure;
553
554 if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
555 goto nla_put_failure;
556
557 if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
558 status = NFCT_HELPER_STATUS_ENABLED;
559 else
560 status = NFCT_HELPER_STATUS_DISABLED;
561
562 if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
563 goto nla_put_failure;
564
565 nlmsg_end(skb, nlh);
566 return skb->len;
567
568 nlmsg_failure:
569 nla_put_failure:
570 nlmsg_cancel(skb, nlh);
571 return -1;
572 }
573
574 static int
nfnl_cthelper_dump_table(struct sk_buff * skb,struct netlink_callback * cb)575 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
576 {
577 struct nf_conntrack_helper *cur, *last;
578
579 rcu_read_lock();
580 last = (struct nf_conntrack_helper *)cb->args[1];
581 for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
582 restart:
583 hlist_for_each_entry_rcu(cur,
584 &nf_ct_helper_hash[cb->args[0]], hnode) {
585
586 /* skip non-userspace conntrack helpers. */
587 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
588 continue;
589
590 if (cb->args[1]) {
591 if (cur != last)
592 continue;
593 cb->args[1] = 0;
594 }
595 if (nfnl_cthelper_fill_info(skb,
596 NETLINK_CB(cb->skb).portid,
597 cb->nlh->nlmsg_seq,
598 NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
599 NFNL_MSG_CTHELPER_NEW, cur) < 0) {
600 cb->args[1] = (unsigned long)cur;
601 goto out;
602 }
603 }
604 if (cb->args[1]) {
605 cb->args[1] = 0;
606 goto restart;
607 }
608 }
609 out:
610 rcu_read_unlock();
611 return skb->len;
612 }
613
nfnl_cthelper_get(struct sk_buff * skb,const struct nfnl_info * info,const struct nlattr * const tb[])614 static int nfnl_cthelper_get(struct sk_buff *skb, const struct nfnl_info *info,
615 const struct nlattr * const tb[])
616 {
617 int ret = -ENOENT;
618 struct nf_conntrack_helper *cur;
619 struct sk_buff *skb2;
620 char *helper_name = NULL;
621 struct nf_conntrack_tuple tuple;
622 struct nfnl_cthelper *nlcth;
623 bool tuple_set = false;
624
625 if (!capable(CAP_NET_ADMIN))
626 return -EPERM;
627
628 if (info->nlh->nlmsg_flags & NLM_F_DUMP) {
629 struct netlink_dump_control c = {
630 .dump = nfnl_cthelper_dump_table,
631 };
632 return netlink_dump_start(info->sk, skb, info->nlh, &c);
633 }
634
635 if (tb[NFCTH_NAME])
636 helper_name = nla_data(tb[NFCTH_NAME]);
637
638 if (tb[NFCTH_TUPLE]) {
639 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
640 if (ret < 0)
641 return ret;
642
643 tuple_set = true;
644 }
645
646 list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
647 cur = &nlcth->helper;
648 if (helper_name &&
649 strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
650 continue;
651
652 if (tuple_set &&
653 (tuple.src.l3num != cur->tuple.src.l3num ||
654 tuple.dst.protonum != cur->tuple.dst.protonum))
655 continue;
656
657 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
658 if (skb2 == NULL) {
659 ret = -ENOMEM;
660 break;
661 }
662
663 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
664 info->nlh->nlmsg_seq,
665 NFNL_MSG_TYPE(info->nlh->nlmsg_type),
666 NFNL_MSG_CTHELPER_NEW, cur);
667 if (ret <= 0) {
668 kfree_skb(skb2);
669 break;
670 }
671
672 ret = nfnetlink_unicast(skb2, info->net, NETLINK_CB(skb).portid);
673 break;
674 }
675
676 return ret;
677 }
678
nfnl_cthelper_del(struct sk_buff * skb,const struct nfnl_info * info,const struct nlattr * const tb[])679 static int nfnl_cthelper_del(struct sk_buff *skb, const struct nfnl_info *info,
680 const struct nlattr * const tb[])
681 {
682 char *helper_name = NULL;
683 struct nf_conntrack_helper *cur;
684 struct nf_conntrack_tuple tuple;
685 bool tuple_set = false, found = false;
686 struct nfnl_cthelper *nlcth, *n;
687 int j = 0, ret;
688
689 if (!capable(CAP_NET_ADMIN))
690 return -EPERM;
691
692 if (tb[NFCTH_NAME])
693 helper_name = nla_data(tb[NFCTH_NAME]);
694
695 if (tb[NFCTH_TUPLE]) {
696 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
697 if (ret < 0)
698 return ret;
699
700 tuple_set = true;
701 }
702
703 ret = -ENOENT;
704 list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
705 cur = &nlcth->helper;
706 j++;
707
708 if (helper_name &&
709 strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
710 continue;
711
712 if (tuple_set &&
713 (tuple.src.l3num != cur->tuple.src.l3num ||
714 tuple.dst.protonum != cur->tuple.dst.protonum))
715 continue;
716
717 if (refcount_dec_if_one(&cur->refcnt)) {
718 found = true;
719 nf_conntrack_helper_unregister(cur);
720 kfree(cur->expect_policy);
721
722 list_del(&nlcth->list);
723 kfree(nlcth);
724 } else {
725 ret = -EBUSY;
726 }
727 }
728
729 /* Make sure we return success if we flush and there is no helpers */
730 return (found || j == 0) ? 0 : ret;
731 }
732
733 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
734 [NFCTH_NAME] = { .type = NLA_NUL_STRING,
735 .len = NF_CT_HELPER_NAME_LEN-1 },
736 [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
737 [NFCTH_PRIV_DATA_LEN] = { .type = NLA_U32, },
738 [NFCTH_STATUS] = { .type = NLA_U32, },
739 };
740
741 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
742 [NFNL_MSG_CTHELPER_NEW] = {
743 .call = nfnl_cthelper_new,
744 .type = NFNL_CB_MUTEX,
745 .attr_count = NFCTH_MAX,
746 .policy = nfnl_cthelper_policy
747 },
748 [NFNL_MSG_CTHELPER_GET] = {
749 .call = nfnl_cthelper_get,
750 .type = NFNL_CB_MUTEX,
751 .attr_count = NFCTH_MAX,
752 .policy = nfnl_cthelper_policy
753 },
754 [NFNL_MSG_CTHELPER_DEL] = {
755 .call = nfnl_cthelper_del,
756 .type = NFNL_CB_MUTEX,
757 .attr_count = NFCTH_MAX,
758 .policy = nfnl_cthelper_policy
759 },
760 };
761
762 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
763 .name = "cthelper",
764 .subsys_id = NFNL_SUBSYS_CTHELPER,
765 .cb_count = NFNL_MSG_CTHELPER_MAX,
766 .cb = nfnl_cthelper_cb,
767 };
768
769 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
770
nfnl_cthelper_init(void)771 static int __init nfnl_cthelper_init(void)
772 {
773 int ret;
774
775 ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
776 if (ret < 0) {
777 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
778 goto err_out;
779 }
780 return 0;
781 err_out:
782 return ret;
783 }
784
nfnl_cthelper_exit(void)785 static void __exit nfnl_cthelper_exit(void)
786 {
787 struct nf_conntrack_helper *cur;
788 struct nfnl_cthelper *nlcth, *n;
789
790 nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
791
792 list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
793 cur = &nlcth->helper;
794
795 nf_conntrack_helper_unregister(cur);
796 kfree(cur->expect_policy);
797 kfree(nlcth);
798 }
799 }
800
801 module_init(nfnl_cthelper_init);
802 module_exit(nfnl_cthelper_exit);
803