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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 <net/netlink.h>
21#include <net/sock.h>
22
23#include <net/netfilter/nf_conntrack_helper.h>
24#include <net/netfilter/nf_conntrack_expect.h>
25#include <net/netfilter/nf_conntrack_ecache.h>
26
27#include <linux/netfilter/nfnetlink.h>
28#include <linux/netfilter/nfnetlink_conntrack.h>
29#include <linux/netfilter/nfnetlink_cthelper.h>
30
31MODULE_LICENSE("GPL");
32MODULE_AUTHOR("Pablo Neira Ayuso <pablo@netfilter.org>");
33MODULE_DESCRIPTION("nfnl_cthelper: User-space connection tracking helpers");
34
35static int
36nfnl_userspace_cthelper(struct sk_buff *skb, unsigned int protoff,
37 struct nf_conn *ct, enum ip_conntrack_info ctinfo)
38{
39 const struct nf_conn_help *help;
40 struct nf_conntrack_helper *helper;
41
42 help = nfct_help(ct);
43 if (help == NULL)
44 return NF_DROP;
45
46
47 helper = rcu_dereference(help->helper);
48 if (helper == NULL)
49 return NF_DROP;
50
51
52 if ((helper->flags &
53 (NF_CT_HELPER_F_USERSPACE | NF_CT_HELPER_F_CONFIGURED)) ==
54 NF_CT_HELPER_F_USERSPACE)
55 return NF_ACCEPT;
56
57
58 return NF_QUEUE_NR(helper->queue_num) | NF_VERDICT_FLAG_QUEUE_BYPASS;
59}
60
61static const struct nla_policy nfnl_cthelper_tuple_pol[NFCTH_TUPLE_MAX+1] = {
62 [NFCTH_TUPLE_L3PROTONUM] = { .type = NLA_U16, },
63 [NFCTH_TUPLE_L4PROTONUM] = { .type = NLA_U8, },
64};
65
66static int
67nfnl_cthelper_parse_tuple(struct nf_conntrack_tuple *tuple,
68 const struct nlattr *attr)
69{
70 int err;
71 struct nlattr *tb[NFCTH_TUPLE_MAX+1];
72
73 err = nla_parse_nested(tb, NFCTH_TUPLE_MAX, attr, nfnl_cthelper_tuple_pol);
74 if (err < 0)
75 return err;
76
77 if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM])
78 return -EINVAL;
79
80 tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
81 tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
82
83 return 0;
84}
85
86static int
87nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
88{
89 const struct nf_conn_help *help = nfct_help(ct);
90
91 if (attr == NULL)
92 return -EINVAL;
93
94 if (help->helper->data_len == 0)
95 return -EINVAL;
96
97 memcpy(&help->data, nla_data(attr), help->helper->data_len);
98 return 0;
99}
100
101static int
102nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
103{
104 const struct nf_conn_help *help = nfct_help(ct);
105
106 if (help->helper->data_len &&
107 nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
108 goto nla_put_failure;
109
110 return 0;
111
112nla_put_failure:
113 return -ENOSPC;
114}
115
116static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
117 [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
118 .len = NF_CT_HELPER_NAME_LEN-1 },
119 [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
120 [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
121};
122
123static int
124nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
125 const struct nlattr *attr)
126{
127 int err;
128 struct nlattr *tb[NFCTH_POLICY_MAX+1];
129
130 err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr, nfnl_cthelper_expect_pol);
131 if (err < 0)
132 return err;
133
134 if (!tb[NFCTH_POLICY_NAME] ||
135 !tb[NFCTH_POLICY_EXPECT_MAX] ||
136 !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
137 return -EINVAL;
138
139 strncpy(expect_policy->name,
140 nla_data(tb[NFCTH_POLICY_NAME]), NF_CT_HELPER_NAME_LEN);
141 expect_policy->max_expected =
142 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
143 expect_policy->timeout =
144 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
145
146 return 0;
147}
148
149static const struct nla_policy
150nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
151 [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
152};
153
154static int
155nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
156 const struct nlattr *attr)
157{
158 int i, ret;
159 struct nf_conntrack_expect_policy *expect_policy;
160 struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
161
162 ret = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
163 nfnl_cthelper_expect_policy_set);
164 if (ret < 0)
165 return ret;
166
167 if (!tb[NFCTH_POLICY_SET_NUM])
168 return -EINVAL;
169
170 helper->expect_class_max =
171 ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
172
173 if (helper->expect_class_max != 0 &&
174 helper->expect_class_max > NF_CT_MAX_EXPECT_CLASSES)
175 return -EOVERFLOW;
176
177 expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
178 helper->expect_class_max, GFP_KERNEL);
179 if (expect_policy == NULL)
180 return -ENOMEM;
181
182 for (i=0; i<helper->expect_class_max; i++) {
183 if (!tb[NFCTH_POLICY_SET+i])
184 goto err;
185
186 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
187 tb[NFCTH_POLICY_SET+i]);
188 if (ret < 0)
189 goto err;
190 }
191 helper->expect_policy = expect_policy;
192 return 0;
193err:
194 kfree(expect_policy);
195 return -EINVAL;
196}
197
198static int
199nfnl_cthelper_create(const struct nlattr * const tb[],
200 struct nf_conntrack_tuple *tuple)
201{
202 struct nf_conntrack_helper *helper;
203 int ret;
204
205 if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
206 return -EINVAL;
207
208 helper = kzalloc(sizeof(struct nf_conntrack_helper), GFP_KERNEL);
209 if (helper == NULL)
210 return -ENOMEM;
211
212 ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
213 if (ret < 0)
214 goto err;
215
216 strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
217 helper->data_len = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
218 helper->flags |= NF_CT_HELPER_F_USERSPACE;
219 memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
220
221 helper->me = THIS_MODULE;
222 helper->help = nfnl_userspace_cthelper;
223 helper->from_nlattr = nfnl_cthelper_from_nlattr;
224 helper->to_nlattr = nfnl_cthelper_to_nlattr;
225
226
227 if (tb[NFCTH_QUEUE_NUM])
228 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
229
230 if (tb[NFCTH_STATUS]) {
231 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
232
233 switch(status) {
234 case NFCT_HELPER_STATUS_ENABLED:
235 helper->flags |= NF_CT_HELPER_F_CONFIGURED;
236 break;
237 case NFCT_HELPER_STATUS_DISABLED:
238 helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
239 break;
240 }
241 }
242
243 ret = nf_conntrack_helper_register(helper);
244 if (ret < 0)
245 goto err;
246
247 return 0;
248err:
249 kfree(helper);
250 return ret;
251}
252
253static int
254nfnl_cthelper_update(const struct nlattr * const tb[],
255 struct nf_conntrack_helper *helper)
256{
257 int ret;
258
259 if (tb[NFCTH_PRIV_DATA_LEN])
260 return -EBUSY;
261
262 if (tb[NFCTH_POLICY]) {
263 ret = nfnl_cthelper_parse_expect_policy(helper,
264 tb[NFCTH_POLICY]);
265 if (ret < 0)
266 return ret;
267 }
268 if (tb[NFCTH_QUEUE_NUM])
269 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
270
271 if (tb[NFCTH_STATUS]) {
272 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
273
274 switch(status) {
275 case NFCT_HELPER_STATUS_ENABLED:
276 helper->flags |= NF_CT_HELPER_F_CONFIGURED;
277 break;
278 case NFCT_HELPER_STATUS_DISABLED:
279 helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
280 break;
281 }
282 }
283 return 0;
284}
285
286static int
287nfnl_cthelper_new(struct sock *nfnl, struct sk_buff *skb,
288 const struct nlmsghdr *nlh, const struct nlattr * const tb[])
289{
290 const char *helper_name;
291 struct nf_conntrack_helper *cur, *helper = NULL;
292 struct nf_conntrack_tuple tuple;
293 int ret = 0, i;
294
295 if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
296 return -EINVAL;
297
298 helper_name = nla_data(tb[NFCTH_NAME]);
299
300 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
301 if (ret < 0)
302 return ret;
303
304 rcu_read_lock();
305 for (i = 0; i < nf_ct_helper_hsize && !helper; i++) {
306 hlist_for_each_entry_rcu(cur, &nf_ct_helper_hash[i], hnode) {
307
308
309 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
310 continue;
311
312 if (strncmp(cur->name, helper_name,
313 NF_CT_HELPER_NAME_LEN) != 0)
314 continue;
315
316 if ((tuple.src.l3num != cur->tuple.src.l3num ||
317 tuple.dst.protonum != cur->tuple.dst.protonum))
318 continue;
319
320 if (nlh->nlmsg_flags & NLM_F_EXCL) {
321 ret = -EEXIST;
322 goto err;
323 }
324 helper = cur;
325 break;
326 }
327 }
328 rcu_read_unlock();
329
330 if (helper == NULL)
331 ret = nfnl_cthelper_create(tb, &tuple);
332 else
333 ret = nfnl_cthelper_update(tb, helper);
334
335 return ret;
336err:
337 rcu_read_unlock();
338 return ret;
339}
340
341static int
342nfnl_cthelper_dump_tuple(struct sk_buff *skb,
343 struct nf_conntrack_helper *helper)
344{
345 struct nlattr *nest_parms;
346
347 nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
348 if (nest_parms == NULL)
349 goto nla_put_failure;
350
351 if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
352 htons(helper->tuple.src.l3num)))
353 goto nla_put_failure;
354
355 if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
356 goto nla_put_failure;
357
358 nla_nest_end(skb, nest_parms);
359 return 0;
360
361nla_put_failure:
362 return -1;
363}
364
365static int
366nfnl_cthelper_dump_policy(struct sk_buff *skb,
367 struct nf_conntrack_helper *helper)
368{
369 int i;
370 struct nlattr *nest_parms1, *nest_parms2;
371
372 nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
373 if (nest_parms1 == NULL)
374 goto nla_put_failure;
375
376 if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
377 htonl(helper->expect_class_max)))
378 goto nla_put_failure;
379
380 for (i=0; i<helper->expect_class_max; i++) {
381 nest_parms2 = nla_nest_start(skb,
382 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
383 if (nest_parms2 == NULL)
384 goto nla_put_failure;
385
386 if (nla_put_string(skb, NFCTH_POLICY_NAME,
387 helper->expect_policy[i].name))
388 goto nla_put_failure;
389
390 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
391 htonl(helper->expect_policy[i].max_expected)))
392 goto nla_put_failure;
393
394 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
395 htonl(helper->expect_policy[i].timeout)))
396 goto nla_put_failure;
397
398 nla_nest_end(skb, nest_parms2);
399 }
400 nla_nest_end(skb, nest_parms1);
401 return 0;
402
403nla_put_failure:
404 return -1;
405}
406
407static int
408nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
409 int event, struct nf_conntrack_helper *helper)
410{
411 struct nlmsghdr *nlh;
412 struct nfgenmsg *nfmsg;
413 unsigned int flags = portid ? NLM_F_MULTI : 0;
414 int status;
415
416 event |= NFNL_SUBSYS_CTHELPER << 8;
417 nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
418 if (nlh == NULL)
419 goto nlmsg_failure;
420
421 nfmsg = nlmsg_data(nlh);
422 nfmsg->nfgen_family = AF_UNSPEC;
423 nfmsg->version = NFNETLINK_V0;
424 nfmsg->res_id = 0;
425
426 if (nla_put_string(skb, NFCTH_NAME, helper->name))
427 goto nla_put_failure;
428
429 if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
430 goto nla_put_failure;
431
432 if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
433 goto nla_put_failure;
434
435 if (nfnl_cthelper_dump_policy(skb, helper) < 0)
436 goto nla_put_failure;
437
438 if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
439 goto nla_put_failure;
440
441 if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
442 status = NFCT_HELPER_STATUS_ENABLED;
443 else
444 status = NFCT_HELPER_STATUS_DISABLED;
445
446 if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
447 goto nla_put_failure;
448
449 nlmsg_end(skb, nlh);
450 return skb->len;
451
452nlmsg_failure:
453nla_put_failure:
454 nlmsg_cancel(skb, nlh);
455 return -1;
456}
457
458static int
459nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
460{
461 struct nf_conntrack_helper *cur, *last;
462
463 rcu_read_lock();
464 last = (struct nf_conntrack_helper *)cb->args[1];
465 for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
466restart:
467 hlist_for_each_entry_rcu(cur,
468 &nf_ct_helper_hash[cb->args[0]], hnode) {
469
470
471 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
472 continue;
473
474 if (cb->args[1]) {
475 if (cur != last)
476 continue;
477 cb->args[1] = 0;
478 }
479 if (nfnl_cthelper_fill_info(skb,
480 NETLINK_CB(cb->skb).portid,
481 cb->nlh->nlmsg_seq,
482 NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
483 NFNL_MSG_CTHELPER_NEW, cur) < 0) {
484 cb->args[1] = (unsigned long)cur;
485 goto out;
486 }
487 }
488 }
489 if (cb->args[1]) {
490 cb->args[1] = 0;
491 goto restart;
492 }
493out:
494 rcu_read_unlock();
495 return skb->len;
496}
497
498static int
499nfnl_cthelper_get(struct sock *nfnl, struct sk_buff *skb,
500 const struct nlmsghdr *nlh, const struct nlattr * const tb[])
501{
502 int ret = -ENOENT, i;
503 struct nf_conntrack_helper *cur;
504 struct sk_buff *skb2;
505 char *helper_name = NULL;
506 struct nf_conntrack_tuple tuple;
507 bool tuple_set = false;
508
509 if (nlh->nlmsg_flags & NLM_F_DUMP) {
510 struct netlink_dump_control c = {
511 .dump = nfnl_cthelper_dump_table,
512 };
513 return netlink_dump_start(nfnl, skb, nlh, &c);
514 }
515
516 if (tb[NFCTH_NAME])
517 helper_name = nla_data(tb[NFCTH_NAME]);
518
519 if (tb[NFCTH_TUPLE]) {
520 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
521 if (ret < 0)
522 return ret;
523
524 tuple_set = true;
525 }
526
527 for (i = 0; i < nf_ct_helper_hsize; i++) {
528 hlist_for_each_entry_rcu(cur, &nf_ct_helper_hash[i], hnode) {
529
530
531 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
532 continue;
533
534 if (helper_name && strncmp(cur->name, helper_name,
535 NF_CT_HELPER_NAME_LEN) != 0) {
536 continue;
537 }
538 if (tuple_set &&
539 (tuple.src.l3num != cur->tuple.src.l3num ||
540 tuple.dst.protonum != cur->tuple.dst.protonum))
541 continue;
542
543 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
544 if (skb2 == NULL) {
545 ret = -ENOMEM;
546 break;
547 }
548
549 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
550 nlh->nlmsg_seq,
551 NFNL_MSG_TYPE(nlh->nlmsg_type),
552 NFNL_MSG_CTHELPER_NEW, cur);
553 if (ret <= 0) {
554 kfree_skb(skb2);
555 break;
556 }
557
558 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
559 MSG_DONTWAIT);
560 if (ret > 0)
561 ret = 0;
562
563
564 return ret == -EAGAIN ? -ENOBUFS : ret;
565 }
566 }
567 return ret;
568}
569
570static int
571nfnl_cthelper_del(struct sock *nfnl, struct sk_buff *skb,
572 const struct nlmsghdr *nlh, const struct nlattr * const tb[])
573{
574 char *helper_name = NULL;
575 struct nf_conntrack_helper *cur;
576 struct hlist_node *tmp;
577 struct nf_conntrack_tuple tuple;
578 bool tuple_set = false, found = false;
579 int i, j = 0, ret;
580
581 if (tb[NFCTH_NAME])
582 helper_name = nla_data(tb[NFCTH_NAME]);
583
584 if (tb[NFCTH_TUPLE]) {
585 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
586 if (ret < 0)
587 return ret;
588
589 tuple_set = true;
590 }
591
592 for (i = 0; i < nf_ct_helper_hsize; i++) {
593 hlist_for_each_entry_safe(cur, tmp, &nf_ct_helper_hash[i],
594 hnode) {
595
596 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
597 continue;
598
599 j++;
600
601 if (helper_name && strncmp(cur->name, helper_name,
602 NF_CT_HELPER_NAME_LEN) != 0) {
603 continue;
604 }
605 if (tuple_set &&
606 (tuple.src.l3num != cur->tuple.src.l3num ||
607 tuple.dst.protonum != cur->tuple.dst.protonum))
608 continue;
609
610 found = true;
611 nf_conntrack_helper_unregister(cur);
612 }
613 }
614
615 return (found || j == 0) ? 0 : -ENOENT;
616}
617
618static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
619 [NFCTH_NAME] = { .type = NLA_NUL_STRING,
620 .len = NF_CT_HELPER_NAME_LEN-1 },
621 [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
622};
623
624static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
625 [NFNL_MSG_CTHELPER_NEW] = { .call = nfnl_cthelper_new,
626 .attr_count = NFCTH_MAX,
627 .policy = nfnl_cthelper_policy },
628 [NFNL_MSG_CTHELPER_GET] = { .call = nfnl_cthelper_get,
629 .attr_count = NFCTH_MAX,
630 .policy = nfnl_cthelper_policy },
631 [NFNL_MSG_CTHELPER_DEL] = { .call = nfnl_cthelper_del,
632 .attr_count = NFCTH_MAX,
633 .policy = nfnl_cthelper_policy },
634};
635
636static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
637 .name = "cthelper",
638 .subsys_id = NFNL_SUBSYS_CTHELPER,
639 .cb_count = NFNL_MSG_CTHELPER_MAX,
640 .cb = nfnl_cthelper_cb,
641};
642
643MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
644
645static int __init nfnl_cthelper_init(void)
646{
647 int ret;
648
649 ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
650 if (ret < 0) {
651 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
652 goto err_out;
653 }
654 return 0;
655err_out:
656 return ret;
657}
658
659static void __exit nfnl_cthelper_exit(void)
660{
661 struct nf_conntrack_helper *cur;
662 struct hlist_node *tmp;
663 int i;
664
665 nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
666
667 for (i=0; i<nf_ct_helper_hsize; i++) {
668 hlist_for_each_entry_safe(cur, tmp, &nf_ct_helper_hash[i],
669 hnode) {
670
671 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
672 continue;
673
674 nf_conntrack_helper_unregister(cur);
675 }
676 }
677}
678
679module_init(nfnl_cthelper_init);
680module_exit(nfnl_cthelper_exit);
681
