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TOMOYO Linux Cross Reference
Linux/net/netfilter/nfnetlink_cthelper.c

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  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
 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
 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
 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
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
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
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
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
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 
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 
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
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 
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
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
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
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
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 
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 
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 
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 
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 

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