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
29MODULE_LICENSE("GPL");
30MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
31MODULE_DESCRIPTION("nfnl_cthelper: User-space connection tracking helpers");
32
33struct nfnl_cthelper {
34 struct list_head list;
35 struct nf_conntrack_helper helper;
36};
37
38static LIST_HEAD(nfnl_cthelper_list);
39
40static int
41nfnl_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
66static 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
71static int
72nfnl_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, nla: attr,
79 policy: 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(nla: tb[NFCTH_TUPLE_L4PROTONUM]);
91
92 return 0;
93}
94
95static int
96nfnl_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(dest: help->data, src: attr, count: sizeof(help->data));
109 return 0;
110}
111
112static int
113nfnl_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, attrtype: CTA_HELP_INFO, attrlen: helper->data_len, data: &help->data))
121 goto nla_put_failure;
122
123 return 0;
124
125nla_put_failure:
126 return -ENOSPC;
127}
128
129static 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
136static int
137nfnl_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, nla: attr,
144 policy: 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(dst: expect_policy->name,
154 nla: 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
166static const struct nla_policy
167nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
168 [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
169};
170
171static int
172nfnl_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, nla: attr,
181 policy: 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 = kcalloc(class_max,
196 sizeof(struct nf_conntrack_expect_policy),
197 GFP_KERNEL);
198 if (expect_policy == NULL)
199 return -ENOMEM;
200
201 for (i = 0; i < class_max; i++) {
202 if (!tb[NFCTH_POLICY_SET+i])
203 goto err;
204
205 ret = nfnl_cthelper_expect_policy(expect_policy: &expect_policy[i],
206 attr: tb[NFCTH_POLICY_SET+i]);
207 if (ret < 0)
208 goto err;
209 }
210
211 helper->expect_class_max = class_max - 1;
212 helper->expect_policy = expect_policy;
213 return 0;
214err:
215 kfree(objp: expect_policy);
216 return -EINVAL;
217}
218
219static int
220nfnl_cthelper_create(const struct nlattr * const tb[],
221 struct nf_conntrack_tuple *tuple)
222{
223 struct nf_conntrack_helper *helper;
224 struct nfnl_cthelper *nfcth;
225 unsigned int size;
226 int ret;
227
228 if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
229 return -EINVAL;
230
231 nfcth = kzalloc(sizeof(*nfcth), GFP_KERNEL);
232 if (nfcth == NULL)
233 return -ENOMEM;
234 helper = &nfcth->helper;
235
236 ret = nfnl_cthelper_parse_expect_policy(helper, attr: tb[NFCTH_POLICY]);
237 if (ret < 0)
238 goto err1;
239
240 nla_strscpy(dst: helper->name,
241 nla: tb[NFCTH_NAME], NF_CT_HELPER_NAME_LEN);
242 size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
243 if (size > sizeof_field(struct nf_conn_help, data)) {
244 ret = -ENOMEM;
245 goto err2;
246 }
247 helper->data_len = size;
248
249 helper->flags |= NF_CT_HELPER_F_USERSPACE;
250 memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
251
252 helper->me = THIS_MODULE;
253 helper->help = nfnl_userspace_cthelper;
254 helper->from_nlattr = nfnl_cthelper_from_nlattr;
255 helper->to_nlattr = nfnl_cthelper_to_nlattr;
256
257 /* Default to queue number zero, this can be updated at any time. */
258 if (tb[NFCTH_QUEUE_NUM])
259 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
260
261 if (tb[NFCTH_STATUS]) {
262 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
263
264 switch(status) {
265 case NFCT_HELPER_STATUS_ENABLED:
266 helper->flags |= NF_CT_HELPER_F_CONFIGURED;
267 break;
268 case NFCT_HELPER_STATUS_DISABLED:
269 helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
270 break;
271 }
272 }
273
274 ret = nf_conntrack_helper_register(helper);
275 if (ret < 0)
276 goto err2;
277
278 list_add_tail(new: &nfcth->list, head: &nfnl_cthelper_list);
279 return 0;
280err2:
281 kfree(objp: helper->expect_policy);
282err1:
283 kfree(objp: nfcth);
284 return ret;
285}
286
287static int
288nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
289 struct nf_conntrack_expect_policy *new_policy,
290 const struct nlattr *attr)
291{
292 struct nlattr *tb[NFCTH_POLICY_MAX + 1];
293 int err;
294
295 err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_MAX, nla: attr,
296 policy: nfnl_cthelper_expect_pol, NULL);
297 if (err < 0)
298 return err;
299
300 if (!tb[NFCTH_POLICY_NAME] ||
301 !tb[NFCTH_POLICY_EXPECT_MAX] ||
302 !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
303 return -EINVAL;
304
305 if (nla_strcmp(nla: tb[NFCTH_POLICY_NAME], str: policy->name))
306 return -EBUSY;
307
308 new_policy->max_expected =
309 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
310 if (new_policy->max_expected > NF_CT_EXPECT_MAX_CNT)
311 return -EINVAL;
312
313 new_policy->timeout =
314 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
315
316 return 0;
317}
318
319static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
320 struct nf_conntrack_helper *helper)
321{
322 struct nf_conntrack_expect_policy *new_policy;
323 struct nf_conntrack_expect_policy *policy;
324 int i, ret = 0;
325
326 new_policy = kmalloc_array(helper->expect_class_max + 1,
327 sizeof(*new_policy), GFP_KERNEL);
328 if (!new_policy)
329 return -ENOMEM;
330
331 /* Check first that all policy attributes are well-formed, so we don't
332 * leave things in inconsistent state on errors.
333 */
334 for (i = 0; i < helper->expect_class_max + 1; i++) {
335
336 if (!tb[NFCTH_POLICY_SET + i]) {
337 ret = -EINVAL;
338 goto err;
339 }
340
341 ret = nfnl_cthelper_update_policy_one(policy: &helper->expect_policy[i],
342 new_policy: &new_policy[i],
343 attr: tb[NFCTH_POLICY_SET + i]);
344 if (ret < 0)
345 goto err;
346 }
347 /* Now we can safely update them. */
348 for (i = 0; i < helper->expect_class_max + 1; i++) {
349 policy = (struct nf_conntrack_expect_policy *)
350 &helper->expect_policy[i];
351 policy->max_expected = new_policy->max_expected;
352 policy->timeout = new_policy->timeout;
353 }
354
355err:
356 kfree(objp: new_policy);
357 return ret;
358}
359
360static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
361 const struct nlattr *attr)
362{
363 struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
364 unsigned int class_max;
365 int err;
366
367 err = nla_parse_nested_deprecated(tb, NFCTH_POLICY_SET_MAX, nla: attr,
368 policy: nfnl_cthelper_expect_policy_set,
369 NULL);
370 if (err < 0)
371 return err;
372
373 if (!tb[NFCTH_POLICY_SET_NUM])
374 return -EINVAL;
375
376 class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
377 if (helper->expect_class_max + 1 != class_max)
378 return -EBUSY;
379
380 return nfnl_cthelper_update_policy_all(tb, helper);
381}
382
383static int
384nfnl_cthelper_update(const struct nlattr * const tb[],
385 struct nf_conntrack_helper *helper)
386{
387 u32 size;
388 int ret;
389
390 if (tb[NFCTH_PRIV_DATA_LEN]) {
391 size = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
392 if (size != helper->data_len)
393 return -EBUSY;
394 }
395
396 if (tb[NFCTH_POLICY]) {
397 ret = nfnl_cthelper_update_policy(helper, attr: tb[NFCTH_POLICY]);
398 if (ret < 0)
399 return ret;
400 }
401 if (tb[NFCTH_QUEUE_NUM])
402 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
403
404 if (tb[NFCTH_STATUS]) {
405 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
406
407 switch(status) {
408 case NFCT_HELPER_STATUS_ENABLED:
409 helper->flags |= NF_CT_HELPER_F_CONFIGURED;
410 break;
411 case NFCT_HELPER_STATUS_DISABLED:
412 helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
413 break;
414 }
415 }
416 return 0;
417}
418
419static int nfnl_cthelper_new(struct sk_buff *skb, const struct nfnl_info *info,
420 const struct nlattr * const tb[])
421{
422 const char *helper_name;
423 struct nf_conntrack_helper *cur, *helper = NULL;
424 struct nf_conntrack_tuple tuple;
425 struct nfnl_cthelper *nlcth;
426 int ret = 0;
427
428 if (!capable(CAP_NET_ADMIN))
429 return -EPERM;
430
431 if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
432 return -EINVAL;
433
434 helper_name = nla_data(nla: tb[NFCTH_NAME]);
435
436 ret = nfnl_cthelper_parse_tuple(tuple: &tuple, attr: tb[NFCTH_TUPLE]);
437 if (ret < 0)
438 return ret;
439
440 list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
441 cur = &nlcth->helper;
442
443 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
444 continue;
445
446 if ((tuple.src.l3num != cur->tuple.src.l3num ||
447 tuple.dst.protonum != cur->tuple.dst.protonum))
448 continue;
449
450 if (info->nlh->nlmsg_flags & NLM_F_EXCL)
451 return -EEXIST;
452
453 helper = cur;
454 break;
455 }
456
457 if (helper == NULL)
458 ret = nfnl_cthelper_create(tb, tuple: &tuple);
459 else
460 ret = nfnl_cthelper_update(tb, helper);
461
462 return ret;
463}
464
465static int
466nfnl_cthelper_dump_tuple(struct sk_buff *skb,
467 struct nf_conntrack_helper *helper)
468{
469 struct nlattr *nest_parms;
470
471 nest_parms = nla_nest_start(skb, attrtype: NFCTH_TUPLE);
472 if (nest_parms == NULL)
473 goto nla_put_failure;
474
475 if (nla_put_be16(skb, attrtype: NFCTH_TUPLE_L3PROTONUM,
476 htons(helper->tuple.src.l3num)))
477 goto nla_put_failure;
478
479 if (nla_put_u8(skb, attrtype: NFCTH_TUPLE_L4PROTONUM, value: helper->tuple.dst.protonum))
480 goto nla_put_failure;
481
482 nla_nest_end(skb, start: nest_parms);
483 return 0;
484
485nla_put_failure:
486 return -1;
487}
488
489static int
490nfnl_cthelper_dump_policy(struct sk_buff *skb,
491 struct nf_conntrack_helper *helper)
492{
493 int i;
494 struct nlattr *nest_parms1, *nest_parms2;
495
496 nest_parms1 = nla_nest_start(skb, attrtype: NFCTH_POLICY);
497 if (nest_parms1 == NULL)
498 goto nla_put_failure;
499
500 if (nla_put_be32(skb, attrtype: NFCTH_POLICY_SET_NUM,
501 htonl(helper->expect_class_max + 1)))
502 goto nla_put_failure;
503
504 for (i = 0; i < helper->expect_class_max + 1; i++) {
505 nest_parms2 = nla_nest_start(skb, attrtype: (NFCTH_POLICY_SET + i));
506 if (nest_parms2 == NULL)
507 goto nla_put_failure;
508
509 if (nla_put_string(skb, attrtype: NFCTH_POLICY_NAME,
510 str: helper->expect_policy[i].name))
511 goto nla_put_failure;
512
513 if (nla_put_be32(skb, attrtype: NFCTH_POLICY_EXPECT_MAX,
514 htonl(helper->expect_policy[i].max_expected)))
515 goto nla_put_failure;
516
517 if (nla_put_be32(skb, attrtype: NFCTH_POLICY_EXPECT_TIMEOUT,
518 htonl(helper->expect_policy[i].timeout)))
519 goto nla_put_failure;
520
521 nla_nest_end(skb, start: nest_parms2);
522 }
523 nla_nest_end(skb, start: nest_parms1);
524 return 0;
525
526nla_put_failure:
527 return -1;
528}
529
530static int
531nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
532 int event, struct nf_conntrack_helper *helper)
533{
534 struct nlmsghdr *nlh;
535 unsigned int flags = portid ? NLM_F_MULTI : 0;
536 int status;
537
538 event = nfnl_msg_type(NFNL_SUBSYS_CTHELPER, msg_type: event);
539 nlh = nfnl_msg_put(skb, portid, seq, type: event, flags, AF_UNSPEC,
540 NFNETLINK_V0, res_id: 0);
541 if (!nlh)
542 goto nlmsg_failure;
543
544 if (nla_put_string(skb, attrtype: NFCTH_NAME, str: helper->name))
545 goto nla_put_failure;
546
547 if (nla_put_be32(skb, attrtype: NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
548 goto nla_put_failure;
549
550 if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
551 goto nla_put_failure;
552
553 if (nfnl_cthelper_dump_policy(skb, helper) < 0)
554 goto nla_put_failure;
555
556 if (nla_put_be32(skb, attrtype: NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
557 goto nla_put_failure;
558
559 if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
560 status = NFCT_HELPER_STATUS_ENABLED;
561 else
562 status = NFCT_HELPER_STATUS_DISABLED;
563
564 if (nla_put_be32(skb, attrtype: NFCTH_STATUS, htonl(status)))
565 goto nla_put_failure;
566
567 nlmsg_end(skb, nlh);
568 return skb->len;
569
570nlmsg_failure:
571nla_put_failure:
572 nlmsg_cancel(skb, nlh);
573 return -1;
574}
575
576static int
577nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
578{
579 struct nf_conntrack_helper *cur, *last;
580
581 rcu_read_lock();
582 last = (struct nf_conntrack_helper *)cb->args[1];
583 for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
584restart:
585 hlist_for_each_entry_rcu(cur,
586 &nf_ct_helper_hash[cb->args[0]], hnode) {
587
588 /* skip non-userspace conntrack helpers. */
589 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
590 continue;
591
592 if (cb->args[1]) {
593 if (cur != last)
594 continue;
595 cb->args[1] = 0;
596 }
597 if (nfnl_cthelper_fill_info(skb,
598 NETLINK_CB(cb->skb).portid,
599 seq: cb->nlh->nlmsg_seq,
600 NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
601 event: NFNL_MSG_CTHELPER_NEW, helper: cur) < 0) {
602 cb->args[1] = (unsigned long)cur;
603 goto out;
604 }
605 }
606 }
607 if (cb->args[1]) {
608 cb->args[1] = 0;
609 goto restart;
610 }
611out:
612 rcu_read_unlock();
613 return skb->len;
614}
615
616static int nfnl_cthelper_get(struct sk_buff *skb, const struct nfnl_info *info,
617 const struct nlattr * const tb[])
618{
619 int ret = -ENOENT;
620 struct nf_conntrack_helper *cur;
621 struct sk_buff *skb2;
622 char *helper_name = NULL;
623 struct nf_conntrack_tuple tuple;
624 struct nfnl_cthelper *nlcth;
625 bool tuple_set = false;
626
627 if (!capable(CAP_NET_ADMIN))
628 return -EPERM;
629
630 if (info->nlh->nlmsg_flags & NLM_F_DUMP) {
631 struct netlink_dump_control c = {
632 .dump = nfnl_cthelper_dump_table,
633 };
634 return netlink_dump_start(ssk: info->sk, skb, nlh: info->nlh, control: &c);
635 }
636
637 if (tb[NFCTH_NAME])
638 helper_name = nla_data(nla: tb[NFCTH_NAME]);
639
640 if (tb[NFCTH_TUPLE]) {
641 ret = nfnl_cthelper_parse_tuple(tuple: &tuple, attr: tb[NFCTH_TUPLE]);
642 if (ret < 0)
643 return ret;
644
645 tuple_set = true;
646 }
647
648 list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
649 cur = &nlcth->helper;
650 if (helper_name &&
651 strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
652 continue;
653
654 if (tuple_set &&
655 (tuple.src.l3num != cur->tuple.src.l3num ||
656 tuple.dst.protonum != cur->tuple.dst.protonum))
657 continue;
658
659 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
660 if (skb2 == NULL) {
661 ret = -ENOMEM;
662 break;
663 }
664
665 ret = nfnl_cthelper_fill_info(skb: skb2, NETLINK_CB(skb).portid,
666 seq: info->nlh->nlmsg_seq,
667 NFNL_MSG_TYPE(info->nlh->nlmsg_type),
668 event: NFNL_MSG_CTHELPER_NEW, helper: cur);
669 if (ret <= 0) {
670 kfree_skb(skb: skb2);
671 break;
672 }
673
674 ret = nfnetlink_unicast(skb: skb2, net: info->net, NETLINK_CB(skb).portid);
675 break;
676 }
677
678 return ret;
679}
680
681static int nfnl_cthelper_del(struct sk_buff *skb, const struct nfnl_info *info,
682 const struct nlattr * const tb[])
683{
684 char *helper_name = NULL;
685 struct nf_conntrack_helper *cur;
686 struct nf_conntrack_tuple tuple;
687 bool tuple_set = false, found = false;
688 struct nfnl_cthelper *nlcth, *n;
689 int j = 0, ret;
690
691 if (!capable(CAP_NET_ADMIN))
692 return -EPERM;
693
694 if (tb[NFCTH_NAME])
695 helper_name = nla_data(nla: tb[NFCTH_NAME]);
696
697 if (tb[NFCTH_TUPLE]) {
698 ret = nfnl_cthelper_parse_tuple(tuple: &tuple, attr: tb[NFCTH_TUPLE]);
699 if (ret < 0)
700 return ret;
701
702 tuple_set = true;
703 }
704
705 ret = -ENOENT;
706 list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
707 cur = &nlcth->helper;
708 j++;
709
710 if (helper_name &&
711 strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
712 continue;
713
714 if (tuple_set &&
715 (tuple.src.l3num != cur->tuple.src.l3num ||
716 tuple.dst.protonum != cur->tuple.dst.protonum))
717 continue;
718
719 if (refcount_dec_if_one(r: &cur->refcnt)) {
720 found = true;
721 nf_conntrack_helper_unregister(cur);
722 kfree(objp: cur->expect_policy);
723
724 list_del(entry: &nlcth->list);
725 kfree(objp: nlcth);
726 } else {
727 ret = -EBUSY;
728 }
729 }
730
731 /* Make sure we return success if we flush and there is no helpers */
732 return (found || j == 0) ? 0 : ret;
733}
734
735static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
736 [NFCTH_NAME] = { .type = NLA_NUL_STRING,
737 .len = NF_CT_HELPER_NAME_LEN-1 },
738 [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
739 [NFCTH_PRIV_DATA_LEN] = { .type = NLA_U32, },
740 [NFCTH_STATUS] = { .type = NLA_U32, },
741};
742
743static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
744 [NFNL_MSG_CTHELPER_NEW] = {
745 .call = nfnl_cthelper_new,
746 .type = NFNL_CB_MUTEX,
747 .attr_count = NFCTH_MAX,
748 .policy = nfnl_cthelper_policy
749 },
750 [NFNL_MSG_CTHELPER_GET] = {
751 .call = nfnl_cthelper_get,
752 .type = NFNL_CB_MUTEX,
753 .attr_count = NFCTH_MAX,
754 .policy = nfnl_cthelper_policy
755 },
756 [NFNL_MSG_CTHELPER_DEL] = {
757 .call = nfnl_cthelper_del,
758 .type = NFNL_CB_MUTEX,
759 .attr_count = NFCTH_MAX,
760 .policy = nfnl_cthelper_policy
761 },
762};
763
764static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
765 .name = "cthelper",
766 .subsys_id = NFNL_SUBSYS_CTHELPER,
767 .cb_count = NFNL_MSG_CTHELPER_MAX,
768 .cb = nfnl_cthelper_cb,
769};
770
771MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
772
773static int __init nfnl_cthelper_init(void)
774{
775 int ret;
776
777 ret = nfnetlink_subsys_register(n: &nfnl_cthelper_subsys);
778 if (ret < 0) {
779 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
780 goto err_out;
781 }
782 return 0;
783err_out:
784 return ret;
785}
786
787static void __exit nfnl_cthelper_exit(void)
788{
789 struct nf_conntrack_helper *cur;
790 struct nfnl_cthelper *nlcth, *n;
791
792 nfnetlink_subsys_unregister(n: &nfnl_cthelper_subsys);
793
794 list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
795 cur = &nlcth->helper;
796
797 nf_conntrack_helper_unregister(cur);
798 kfree(objp: cur->expect_policy);
799 kfree(objp: nlcth);
800 }
801}
802
803module_init(nfnl_cthelper_init);
804module_exit(nfnl_cthelper_exit);
805

source code of linux/net/netfilter/nfnetlink_cthelper.c