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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
81 memset(tuple, 0, sizeof(struct nf_conntrack_tuple));
82
83 tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
84 tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
85
86 return 0;
87}
88
89static int
90nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
91{
92 struct nf_conn_help *help = nfct_help(ct);
93
94 if (attr == NULL)
95 return -EINVAL;
96
97 if (help->helper->data_len == 0)
98 return -EINVAL;
99
100 memcpy(help->data, nla_data(attr), help->helper->data_len);
101 return 0;
102}
103
104static int
105nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
106{
107 const struct nf_conn_help *help = nfct_help(ct);
108
109 if (help->helper->data_len &&
110 nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
111 goto nla_put_failure;
112
113 return 0;
114
115nla_put_failure:
116 return -ENOSPC;
117}
118
119static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
120 [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
121 .len = NF_CT_HELPER_NAME_LEN-1 },
122 [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
123 [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
124};
125
126static int
127nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
128 const struct nlattr *attr)
129{
130 int err;
131 struct nlattr *tb[NFCTH_POLICY_MAX+1];
132
133 err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr, nfnl_cthelper_expect_pol);
134 if (err < 0)
135 return err;
136
137 if (!tb[NFCTH_POLICY_NAME] ||
138 !tb[NFCTH_POLICY_EXPECT_MAX] ||
139 !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
140 return -EINVAL;
141
142 strncpy(expect_policy->name,
143 nla_data(tb[NFCTH_POLICY_NAME]), NF_CT_HELPER_NAME_LEN);
144 expect_policy->max_expected =
145 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
146 expect_policy->timeout =
147 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
148
149 return 0;
150}
151
152static const struct nla_policy
153nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
154 [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
155};
156
157static int
158nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
159 const struct nlattr *attr)
160{
161 int i, ret;
162 struct nf_conntrack_expect_policy *expect_policy;
163 struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
164
165 ret = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
166 nfnl_cthelper_expect_policy_set);
167 if (ret < 0)
168 return ret;
169
170 if (!tb[NFCTH_POLICY_SET_NUM])
171 return -EINVAL;
172
173 helper->expect_class_max =
174 ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
175
176 if (helper->expect_class_max != 0 &&
177 helper->expect_class_max > NF_CT_MAX_EXPECT_CLASSES)
178 return -EOVERFLOW;
179
180 expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
181 helper->expect_class_max, GFP_KERNEL);
182 if (expect_policy == NULL)
183 return -ENOMEM;
184
185 for (i=0; i<helper->expect_class_max; i++) {
186 if (!tb[NFCTH_POLICY_SET+i])
187 goto err;
188
189 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
190 tb[NFCTH_POLICY_SET+i]);
191 if (ret < 0)
192 goto err;
193 }
194 helper->expect_policy = expect_policy;
195 return 0;
196err:
197 kfree(expect_policy);
198 return -EINVAL;
199}
200
201static int
202nfnl_cthelper_create(const struct nlattr * const tb[],
203 struct nf_conntrack_tuple *tuple)
204{
205 struct nf_conntrack_helper *helper;
206 int ret;
207
208 if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
209 return -EINVAL;
210
211 helper = kzalloc(sizeof(struct nf_conntrack_helper), GFP_KERNEL);
212 if (helper == NULL)
213 return -ENOMEM;
214
215 ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
216 if (ret < 0)
217 goto err;
218
219 strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
220 helper->data_len = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
221 helper->flags |= NF_CT_HELPER_F_USERSPACE;
222 memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
223
224 helper->me = THIS_MODULE;
225 helper->help = nfnl_userspace_cthelper;
226 helper->from_nlattr = nfnl_cthelper_from_nlattr;
227 helper->to_nlattr = nfnl_cthelper_to_nlattr;
228
229
230 if (tb[NFCTH_QUEUE_NUM])
231 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
232
233 if (tb[NFCTH_STATUS]) {
234 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
235
236 switch(status) {
237 case NFCT_HELPER_STATUS_ENABLED:
238 helper->flags |= NF_CT_HELPER_F_CONFIGURED;
239 break;
240 case NFCT_HELPER_STATUS_DISABLED:
241 helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
242 break;
243 }
244 }
245
246 ret = nf_conntrack_helper_register(helper);
247 if (ret < 0)
248 goto err;
249
250 return 0;
251err:
252 kfree(helper);
253 return ret;
254}
255
256static int
257nfnl_cthelper_update(const struct nlattr * const tb[],
258 struct nf_conntrack_helper *helper)
259{
260 int ret;
261
262 if (tb[NFCTH_PRIV_DATA_LEN])
263 return -EBUSY;
264
265 if (tb[NFCTH_POLICY]) {
266 ret = nfnl_cthelper_parse_expect_policy(helper,
267 tb[NFCTH_POLICY]);
268 if (ret < 0)
269 return ret;
270 }
271 if (tb[NFCTH_QUEUE_NUM])
272 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
273
274 if (tb[NFCTH_STATUS]) {
275 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
276
277 switch(status) {
278 case NFCT_HELPER_STATUS_ENABLED:
279 helper->flags |= NF_CT_HELPER_F_CONFIGURED;
280 break;
281 case NFCT_HELPER_STATUS_DISABLED:
282 helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
283 break;
284 }
285 }
286 return 0;
287}
288
289static int nfnl_cthelper_new(struct net *net, struct sock *nfnl,
290 struct sk_buff *skb, const struct nlmsghdr *nlh,
291 const struct nlattr * const tb[])
292{
293 const char *helper_name;
294 struct nf_conntrack_helper *cur, *helper = NULL;
295 struct nf_conntrack_tuple tuple;
296 int ret = 0, i;
297
298 if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
299 return -EINVAL;
300
301 helper_name = nla_data(tb[NFCTH_NAME]);
302
303 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
304 if (ret < 0)
305 return ret;
306
307 rcu_read_lock();
308 for (i = 0; i < nf_ct_helper_hsize && !helper; i++) {
309 hlist_for_each_entry_rcu(cur, &nf_ct_helper_hash[i], hnode) {
310
311
312 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
313 continue;
314
315 if (strncmp(cur->name, helper_name,
316 NF_CT_HELPER_NAME_LEN) != 0)
317 continue;
318
319 if ((tuple.src.l3num != cur->tuple.src.l3num ||
320 tuple.dst.protonum != cur->tuple.dst.protonum))
321 continue;
322
323 if (nlh->nlmsg_flags & NLM_F_EXCL) {
324 ret = -EEXIST;
325 goto err;
326 }
327 helper = cur;
328 break;
329 }
330 }
331 rcu_read_unlock();
332
333 if (helper == NULL)
334 ret = nfnl_cthelper_create(tb, &tuple);
335 else
336 ret = nfnl_cthelper_update(tb, helper);
337
338 return ret;
339err:
340 rcu_read_unlock();
341 return ret;
342}
343
344static int
345nfnl_cthelper_dump_tuple(struct sk_buff *skb,
346 struct nf_conntrack_helper *helper)
347{
348 struct nlattr *nest_parms;
349
350 nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
351 if (nest_parms == NULL)
352 goto nla_put_failure;
353
354 if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
355 htons(helper->tuple.src.l3num)))
356 goto nla_put_failure;
357
358 if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
359 goto nla_put_failure;
360
361 nla_nest_end(skb, nest_parms);
362 return 0;
363
364nla_put_failure:
365 return -1;
366}
367
368static int
369nfnl_cthelper_dump_policy(struct sk_buff *skb,
370 struct nf_conntrack_helper *helper)
371{
372 int i;
373 struct nlattr *nest_parms1, *nest_parms2;
374
375 nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
376 if (nest_parms1 == NULL)
377 goto nla_put_failure;
378
379 if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
380 htonl(helper->expect_class_max)))
381 goto nla_put_failure;
382
383 for (i=0; i<helper->expect_class_max; i++) {
384 nest_parms2 = nla_nest_start(skb,
385 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
386 if (nest_parms2 == NULL)
387 goto nla_put_failure;
388
389 if (nla_put_string(skb, NFCTH_POLICY_NAME,
390 helper->expect_policy[i].name))
391 goto nla_put_failure;
392
393 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
394 htonl(helper->expect_policy[i].max_expected)))
395 goto nla_put_failure;
396
397 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
398 htonl(helper->expect_policy[i].timeout)))
399 goto nla_put_failure;
400
401 nla_nest_end(skb, nest_parms2);
402 }
403 nla_nest_end(skb, nest_parms1);
404 return 0;
405
406nla_put_failure:
407 return -1;
408}
409
410static int
411nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
412 int event, struct nf_conntrack_helper *helper)
413{
414 struct nlmsghdr *nlh;
415 struct nfgenmsg *nfmsg;
416 unsigned int flags = portid ? NLM_F_MULTI : 0;
417 int status;
418
419 event |= NFNL_SUBSYS_CTHELPER << 8;
420 nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
421 if (nlh == NULL)
422 goto nlmsg_failure;
423
424 nfmsg = nlmsg_data(nlh);
425 nfmsg->nfgen_family = AF_UNSPEC;
426 nfmsg->version = NFNETLINK_V0;
427 nfmsg->res_id = 0;
428
429 if (nla_put_string(skb, NFCTH_NAME, helper->name))
430 goto nla_put_failure;
431
432 if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
433 goto nla_put_failure;
434
435 if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
436 goto nla_put_failure;
437
438 if (nfnl_cthelper_dump_policy(skb, helper) < 0)
439 goto nla_put_failure;
440
441 if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
442 goto nla_put_failure;
443
444 if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
445 status = NFCT_HELPER_STATUS_ENABLED;
446 else
447 status = NFCT_HELPER_STATUS_DISABLED;
448
449 if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
450 goto nla_put_failure;
451
452 nlmsg_end(skb, nlh);
453 return skb->len;
454
455nlmsg_failure:
456nla_put_failure:
457 nlmsg_cancel(skb, nlh);
458 return -1;
459}
460
461static int
462nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
463{
464 struct nf_conntrack_helper *cur, *last;
465
466 rcu_read_lock();
467 last = (struct nf_conntrack_helper *)cb->args[1];
468 for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
469restart:
470 hlist_for_each_entry_rcu(cur,
471 &nf_ct_helper_hash[cb->args[0]], hnode) {
472
473
474 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
475 continue;
476
477 if (cb->args[1]) {
478 if (cur != last)
479 continue;
480 cb->args[1] = 0;
481 }
482 if (nfnl_cthelper_fill_info(skb,
483 NETLINK_CB(cb->skb).portid,
484 cb->nlh->nlmsg_seq,
485 NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
486 NFNL_MSG_CTHELPER_NEW, cur) < 0) {
487 cb->args[1] = (unsigned long)cur;
488 goto out;
489 }
490 }
491 }
492 if (cb->args[1]) {
493 cb->args[1] = 0;
494 goto restart;
495 }
496out:
497 rcu_read_unlock();
498 return skb->len;
499}
500
501static int nfnl_cthelper_get(struct net *net, struct sock *nfnl,
502 struct sk_buff *skb, const struct nlmsghdr *nlh,
503 const struct nlattr * const tb[])
504{
505 int ret = -ENOENT, i;
506 struct nf_conntrack_helper *cur;
507 struct sk_buff *skb2;
508 char *helper_name = NULL;
509 struct nf_conntrack_tuple tuple;
510 bool tuple_set = false;
511
512 if (nlh->nlmsg_flags & NLM_F_DUMP) {
513 struct netlink_dump_control c = {
514 .dump = nfnl_cthelper_dump_table,
515 };
516 return netlink_dump_start(nfnl, skb, nlh, &c);
517 }
518
519 if (tb[NFCTH_NAME])
520 helper_name = nla_data(tb[NFCTH_NAME]);
521
522 if (tb[NFCTH_TUPLE]) {
523 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
524 if (ret < 0)
525 return ret;
526
527 tuple_set = true;
528 }
529
530 for (i = 0; i < nf_ct_helper_hsize; i++) {
531 hlist_for_each_entry_rcu(cur, &nf_ct_helper_hash[i], hnode) {
532
533
534 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
535 continue;
536
537 if (helper_name && strncmp(cur->name, helper_name,
538 NF_CT_HELPER_NAME_LEN) != 0) {
539 continue;
540 }
541 if (tuple_set &&
542 (tuple.src.l3num != cur->tuple.src.l3num ||
543 tuple.dst.protonum != cur->tuple.dst.protonum))
544 continue;
545
546 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
547 if (skb2 == NULL) {
548 ret = -ENOMEM;
549 break;
550 }
551
552 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
553 nlh->nlmsg_seq,
554 NFNL_MSG_TYPE(nlh->nlmsg_type),
555 NFNL_MSG_CTHELPER_NEW, cur);
556 if (ret <= 0) {
557 kfree_skb(skb2);
558 break;
559 }
560
561 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
562 MSG_DONTWAIT);
563 if (ret > 0)
564 ret = 0;
565
566
567 return ret == -EAGAIN ? -ENOBUFS : ret;
568 }
569 }
570 return ret;
571}
572
573static int nfnl_cthelper_del(struct net *net, struct sock *nfnl,
574 struct sk_buff *skb, const struct nlmsghdr *nlh,
575 const struct nlattr * const tb[])
576{
577 char *helper_name = NULL;
578 struct nf_conntrack_helper *cur;
579 struct hlist_node *tmp;
580 struct nf_conntrack_tuple tuple;
581 bool tuple_set = false, found = false;
582 int i, j = 0, ret;
583
584 if (tb[NFCTH_NAME])
585 helper_name = nla_data(tb[NFCTH_NAME]);
586
587 if (tb[NFCTH_TUPLE]) {
588 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
589 if (ret < 0)
590 return ret;
591
592 tuple_set = true;
593 }
594
595 for (i = 0; i < nf_ct_helper_hsize; i++) {
596 hlist_for_each_entry_safe(cur, tmp, &nf_ct_helper_hash[i],
597 hnode) {
598
599 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
600 continue;
601
602 j++;
603
604 if (helper_name && strncmp(cur->name, helper_name,
605 NF_CT_HELPER_NAME_LEN) != 0) {
606 continue;
607 }
608 if (tuple_set &&
609 (tuple.src.l3num != cur->tuple.src.l3num ||
610 tuple.dst.protonum != cur->tuple.dst.protonum))
611 continue;
612
613 found = true;
614 nf_conntrack_helper_unregister(cur);
615 }
616 }
617
618 return (found || j == 0) ? 0 : -ENOENT;
619}
620
621static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
622 [NFCTH_NAME] = { .type = NLA_NUL_STRING,
623 .len = NF_CT_HELPER_NAME_LEN-1 },
624 [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
625};
626
627static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
628 [NFNL_MSG_CTHELPER_NEW] = { .call = nfnl_cthelper_new,
629 .attr_count = NFCTH_MAX,
630 .policy = nfnl_cthelper_policy },
631 [NFNL_MSG_CTHELPER_GET] = { .call = nfnl_cthelper_get,
632 .attr_count = NFCTH_MAX,
633 .policy = nfnl_cthelper_policy },
634 [NFNL_MSG_CTHELPER_DEL] = { .call = nfnl_cthelper_del,
635 .attr_count = NFCTH_MAX,
636 .policy = nfnl_cthelper_policy },
637};
638
639static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
640 .name = "cthelper",
641 .subsys_id = NFNL_SUBSYS_CTHELPER,
642 .cb_count = NFNL_MSG_CTHELPER_MAX,
643 .cb = nfnl_cthelper_cb,
644};
645
646MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
647
648static int __init nfnl_cthelper_init(void)
649{
650 int ret;
651
652 ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
653 if (ret < 0) {
654 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
655 goto err_out;
656 }
657 return 0;
658err_out:
659 return ret;
660}
661
662static void __exit nfnl_cthelper_exit(void)
663{
664 struct nf_conntrack_helper *cur;
665 struct hlist_node *tmp;
666 int i;
667
668 nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
669
670 for (i=0; i<nf_ct_helper_hsize; i++) {
671 hlist_for_each_entry_safe(cur, tmp, &nf_ct_helper_hash[i],
672 hnode) {
673
674 if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
675 continue;
676
677 nf_conntrack_helper_unregister(cur);
678 }
679 }
680}
681
682module_init(nfnl_cthelper_init);
683module_exit(nfnl_cthelper_exit);
684
