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