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Linux/net/netfilter/nfnetlink_cthelper.c

Version: ~ [ linux-5.2-rc1 ] ~ [ linux-5.1.2 ] ~ [ linux-5.0.16 ] ~ [ linux-4.20.17 ] ~ [ linux-4.19.43 ] ~ [ linux-4.18.20 ] ~ [ linux-4.17.19 ] ~ [ linux-4.16.18 ] ~ [ linux-4.15.18 ] ~ [ linux-4.14.119 ] ~ [ linux-4.13.16 ] ~ [ linux-4.12.14 ] ~ [ linux-4.11.12 ] ~ [ linux-4.10.17 ] ~ [ linux-4.9.176 ] ~ [ linux-4.8.17 ] ~ [ linux-4.7.10 ] ~ [ linux-4.6.7 ] ~ [ linux-4.5.7 ] ~ [ linux-4.4.179 ] ~ [ linux-4.3.6 ] ~ [ linux-4.2.8 ] ~ [ linux-4.1.52 ] ~ [ linux-4.0.9 ] ~ [ linux-3.19.8 ] ~ [ linux-3.18.139 ] ~ [ linux-3.17.8 ] ~ [ linux-3.16.67 ] ~ [ linux-3.15.10 ] ~ [ linux-3.14.79 ] ~ [ linux-3.13.11 ] ~ [ linux-3.12.74 ] ~ [ linux-3.11.10 ] ~ [ linux-3.10.108 ] ~ [ linux-3.9.11 ] ~ [ linux-3.8.13 ] ~ [ linux-3.7.10 ] ~ [ linux-3.6.11 ] ~ [ linux-3.5.7 ] ~ [ linux-3.4.113 ] ~ [ linux-3.3.8 ] ~ [ linux-3.2.102 ] ~ [ linux-3.1.10 ] ~ [ linux-3.0.101 ] ~ [ linux-2.6.39.4 ] ~ [ linux-2.6.38.8 ] ~ [ linux-2.6.37.6 ] ~ [ linux-2.6.36.4 ] ~ [ linux-2.6.35.14 ] ~ [ linux-2.6.34.15 ] ~ [ linux-2.6.33.20 ] ~ [ linux-2.6.32.71 ] ~ [ linux-2.6.0 ] ~ [ linux-2.4.37.11 ] ~ [ unix-v6-master ] ~ [ ccs-tools-1.8.5 ] ~ [ policy-sample ] ~
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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_slow */
 55         helper = rcu_dereference(help->helper);
 56         if (helper == NULL)
 57                 return NF_DROP;
 58 
 59         /* This is an 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, nfnl_cthelper_tuple_pol);
 82         if (err < 0)
 83                 return err;
 84 
 85         if (!tb[NFCTH_TUPLE_L3PROTONUM] || !tb[NFCTH_TUPLE_L4PROTONUM])
 86                 return -EINVAL;
 87 
 88         /* Not all fields are initialized so first zero the tuple */
 89         memset(tuple, 0, sizeof(struct nf_conntrack_tuple));
 90 
 91         tuple->src.l3num = ntohs(nla_get_be16(tb[NFCTH_TUPLE_L3PROTONUM]));
 92         tuple->dst.protonum = nla_get_u8(tb[NFCTH_TUPLE_L4PROTONUM]);
 93 
 94         return 0;
 95 }
 96 
 97 static int
 98 nfnl_cthelper_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
 99 {
100         struct nf_conn_help *help = nfct_help(ct);
101 
102         if (attr == NULL)
103                 return -EINVAL;
104 
105         if (help->helper->data_len == 0)
106                 return -EINVAL;
107 
108         memcpy(help->data, nla_data(attr), help->helper->data_len);
109         return 0;
110 }
111 
112 static int
113 nfnl_cthelper_to_nlattr(struct sk_buff *skb, const struct nf_conn *ct)
114 {
115         const struct nf_conn_help *help = nfct_help(ct);
116 
117         if (help->helper->data_len &&
118             nla_put(skb, CTA_HELP_INFO, help->helper->data_len, &help->data))
119                 goto nla_put_failure;
120 
121         return 0;
122 
123 nla_put_failure:
124         return -ENOSPC;
125 }
126 
127 static const struct nla_policy nfnl_cthelper_expect_pol[NFCTH_POLICY_MAX+1] = {
128         [NFCTH_POLICY_NAME] = { .type = NLA_NUL_STRING,
129                                 .len = NF_CT_HELPER_NAME_LEN-1 },
130         [NFCTH_POLICY_EXPECT_MAX] = { .type = NLA_U32, },
131         [NFCTH_POLICY_EXPECT_TIMEOUT] = { .type = NLA_U32, },
132 };
133 
134 static int
135 nfnl_cthelper_expect_policy(struct nf_conntrack_expect_policy *expect_policy,
136                             const struct nlattr *attr)
137 {
138         int err;
139         struct nlattr *tb[NFCTH_POLICY_MAX+1];
140 
141         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr, nfnl_cthelper_expect_pol);
142         if (err < 0)
143                 return err;
144 
145         if (!tb[NFCTH_POLICY_NAME] ||
146             !tb[NFCTH_POLICY_EXPECT_MAX] ||
147             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
148                 return -EINVAL;
149 
150         strncpy(expect_policy->name,
151                 nla_data(tb[NFCTH_POLICY_NAME]), NF_CT_HELPER_NAME_LEN);
152         expect_policy->max_expected =
153                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
154         expect_policy->timeout =
155                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
156 
157         return 0;
158 }
159 
160 static const struct nla_policy
161 nfnl_cthelper_expect_policy_set[NFCTH_POLICY_SET_MAX+1] = {
162         [NFCTH_POLICY_SET_NUM] = { .type = NLA_U32, },
163 };
164 
165 static int
166 nfnl_cthelper_parse_expect_policy(struct nf_conntrack_helper *helper,
167                                   const struct nlattr *attr)
168 {
169         int i, ret;
170         struct nf_conntrack_expect_policy *expect_policy;
171         struct nlattr *tb[NFCTH_POLICY_SET_MAX+1];
172         unsigned int class_max;
173 
174         ret = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
175                                nfnl_cthelper_expect_policy_set);
176         if (ret < 0)
177                 return ret;
178 
179         if (!tb[NFCTH_POLICY_SET_NUM])
180                 return -EINVAL;
181 
182         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
183         if (class_max == 0)
184                 return -EINVAL;
185         if (class_max > NF_CT_MAX_EXPECT_CLASSES)
186                 return -EOVERFLOW;
187 
188         expect_policy = kzalloc(sizeof(struct nf_conntrack_expect_policy) *
189                                 class_max, GFP_KERNEL);
190         if (expect_policy == NULL)
191                 return -ENOMEM;
192 
193         for (i = 0; i < class_max; i++) {
194                 if (!tb[NFCTH_POLICY_SET+i])
195                         goto err;
196 
197                 ret = nfnl_cthelper_expect_policy(&expect_policy[i],
198                                                   tb[NFCTH_POLICY_SET+i]);
199                 if (ret < 0)
200                         goto err;
201         }
202 
203         helper->expect_class_max = class_max - 1;
204         helper->expect_policy = expect_policy;
205         return 0;
206 err:
207         kfree(expect_policy);
208         return -EINVAL;
209 }
210 
211 static int
212 nfnl_cthelper_create(const struct nlattr * const tb[],
213                      struct nf_conntrack_tuple *tuple)
214 {
215         struct nf_conntrack_helper *helper;
216         struct nfnl_cthelper *nfcth;
217         int ret;
218 
219         if (!tb[NFCTH_TUPLE] || !tb[NFCTH_POLICY] || !tb[NFCTH_PRIV_DATA_LEN])
220                 return -EINVAL;
221 
222         nfcth = kzalloc(sizeof(*nfcth), GFP_KERNEL);
223         if (nfcth == NULL)
224                 return -ENOMEM;
225         helper = &nfcth->helper;
226 
227         ret = nfnl_cthelper_parse_expect_policy(helper, tb[NFCTH_POLICY]);
228         if (ret < 0)
229                 goto err1;
230 
231         strncpy(helper->name, nla_data(tb[NFCTH_NAME]), NF_CT_HELPER_NAME_LEN);
232         helper->data_len = ntohl(nla_get_be32(tb[NFCTH_PRIV_DATA_LEN]));
233         helper->flags |= NF_CT_HELPER_F_USERSPACE;
234         memcpy(&helper->tuple, tuple, sizeof(struct nf_conntrack_tuple));
235 
236         helper->me = THIS_MODULE;
237         helper->help = nfnl_userspace_cthelper;
238         helper->from_nlattr = nfnl_cthelper_from_nlattr;
239         helper->to_nlattr = nfnl_cthelper_to_nlattr;
240 
241         /* Default to queue number zero, this can be updated at any time. */
242         if (tb[NFCTH_QUEUE_NUM])
243                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
244 
245         if (tb[NFCTH_STATUS]) {
246                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
247 
248                 switch(status) {
249                 case NFCT_HELPER_STATUS_ENABLED:
250                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
251                         break;
252                 case NFCT_HELPER_STATUS_DISABLED:
253                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
254                         break;
255                 }
256         }
257 
258         ret = nf_conntrack_helper_register(helper);
259         if (ret < 0)
260                 goto err2;
261 
262         list_add_tail(&nfcth->list, &nfnl_cthelper_list);
263         return 0;
264 err2:
265         kfree(helper->expect_policy);
266 err1:
267         kfree(nfcth);
268         return ret;
269 }
270 
271 static int
272 nfnl_cthelper_update_policy_one(const struct nf_conntrack_expect_policy *policy,
273                                 struct nf_conntrack_expect_policy *new_policy,
274                                 const struct nlattr *attr)
275 {
276         struct nlattr *tb[NFCTH_POLICY_MAX + 1];
277         int err;
278 
279         err = nla_parse_nested(tb, NFCTH_POLICY_MAX, attr,
280                                nfnl_cthelper_expect_pol);
281         if (err < 0)
282                 return err;
283 
284         if (!tb[NFCTH_POLICY_NAME] ||
285             !tb[NFCTH_POLICY_EXPECT_MAX] ||
286             !tb[NFCTH_POLICY_EXPECT_TIMEOUT])
287                 return -EINVAL;
288 
289         if (nla_strcmp(tb[NFCTH_POLICY_NAME], policy->name))
290                 return -EBUSY;
291 
292         new_policy->max_expected =
293                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_MAX]));
294         new_policy->timeout =
295                 ntohl(nla_get_be32(tb[NFCTH_POLICY_EXPECT_TIMEOUT]));
296 
297         return 0;
298 }
299 
300 static int nfnl_cthelper_update_policy_all(struct nlattr *tb[],
301                                            struct nf_conntrack_helper *helper)
302 {
303         struct nf_conntrack_expect_policy new_policy[helper->expect_class_max + 1];
304         struct nf_conntrack_expect_policy *policy;
305         int i, err;
306 
307         /* Check first that all policy attributes are well-formed, so we don't
308          * leave things in inconsistent state on errors.
309          */
310         for (i = 0; i < helper->expect_class_max + 1; i++) {
311 
312                 if (!tb[NFCTH_POLICY_SET + i])
313                         return -EINVAL;
314 
315                 err = nfnl_cthelper_update_policy_one(&helper->expect_policy[i],
316                                                       &new_policy[i],
317                                                       tb[NFCTH_POLICY_SET + i]);
318                 if (err < 0)
319                         return err;
320         }
321         /* Now we can safely update them. */
322         for (i = 0; i < helper->expect_class_max + 1; i++) {
323                 policy = (struct nf_conntrack_expect_policy *)
324                                 &helper->expect_policy[i];
325                 policy->max_expected = new_policy->max_expected;
326                 policy->timeout = new_policy->timeout;
327         }
328 
329         return 0;
330 }
331 
332 static int nfnl_cthelper_update_policy(struct nf_conntrack_helper *helper,
333                                        const struct nlattr *attr)
334 {
335         struct nlattr *tb[NFCTH_POLICY_SET_MAX + 1];
336         unsigned int class_max;
337         int err;
338 
339         err = nla_parse_nested(tb, NFCTH_POLICY_SET_MAX, attr,
340                                nfnl_cthelper_expect_policy_set);
341         if (err < 0)
342                 return err;
343 
344         if (!tb[NFCTH_POLICY_SET_NUM])
345                 return -EINVAL;
346 
347         class_max = ntohl(nla_get_be32(tb[NFCTH_POLICY_SET_NUM]));
348         if (helper->expect_class_max + 1 != class_max)
349                 return -EBUSY;
350 
351         return nfnl_cthelper_update_policy_all(tb, helper);
352 }
353 
354 static int
355 nfnl_cthelper_update(const struct nlattr * const tb[],
356                      struct nf_conntrack_helper *helper)
357 {
358         int ret;
359 
360         if (tb[NFCTH_PRIV_DATA_LEN])
361                 return -EBUSY;
362 
363         if (tb[NFCTH_POLICY]) {
364                 ret = nfnl_cthelper_update_policy(helper, tb[NFCTH_POLICY]);
365                 if (ret < 0)
366                         return ret;
367         }
368         if (tb[NFCTH_QUEUE_NUM])
369                 helper->queue_num = ntohl(nla_get_be32(tb[NFCTH_QUEUE_NUM]));
370 
371         if (tb[NFCTH_STATUS]) {
372                 int status = ntohl(nla_get_be32(tb[NFCTH_STATUS]));
373 
374                 switch(status) {
375                 case NFCT_HELPER_STATUS_ENABLED:
376                         helper->flags |= NF_CT_HELPER_F_CONFIGURED;
377                         break;
378                 case NFCT_HELPER_STATUS_DISABLED:
379                         helper->flags &= ~NF_CT_HELPER_F_CONFIGURED;
380                         break;
381                 }
382         }
383         return 0;
384 }
385 
386 static int
387 nfnl_cthelper_new(struct sock *nfnl, struct sk_buff *skb,
388                   const struct nlmsghdr *nlh, const struct nlattr * const tb[])
389 {
390         const char *helper_name;
391         struct nf_conntrack_helper *cur, *helper = NULL;
392         struct nf_conntrack_tuple tuple;
393         struct nfnl_cthelper *nlcth;
394         int ret = 0;
395 
396         if (!capable(CAP_NET_ADMIN))
397                 return -EPERM;
398 
399         if (!tb[NFCTH_NAME] || !tb[NFCTH_TUPLE])
400                 return -EINVAL;
401 
402         helper_name = nla_data(tb[NFCTH_NAME]);
403 
404         ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
405         if (ret < 0)
406                 return ret;
407 
408         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
409                 cur = &nlcth->helper;
410 
411                 if (strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
412                         continue;
413 
414                 if ((tuple.src.l3num != cur->tuple.src.l3num ||
415                      tuple.dst.protonum != cur->tuple.dst.protonum))
416                         continue;
417 
418                 if (nlh->nlmsg_flags & NLM_F_EXCL)
419                         return -EEXIST;
420 
421                 helper = cur;
422                 break;
423         }
424 
425         if (helper == NULL)
426                 ret = nfnl_cthelper_create(tb, &tuple);
427         else
428                 ret = nfnl_cthelper_update(tb, helper);
429 
430         return ret;
431 }
432 
433 static int
434 nfnl_cthelper_dump_tuple(struct sk_buff *skb,
435                          struct nf_conntrack_helper *helper)
436 {
437         struct nlattr *nest_parms;
438 
439         nest_parms = nla_nest_start(skb, NFCTH_TUPLE | NLA_F_NESTED);
440         if (nest_parms == NULL)
441                 goto nla_put_failure;
442 
443         if (nla_put_be16(skb, NFCTH_TUPLE_L3PROTONUM,
444                          htons(helper->tuple.src.l3num)))
445                 goto nla_put_failure;
446 
447         if (nla_put_u8(skb, NFCTH_TUPLE_L4PROTONUM, helper->tuple.dst.protonum))
448                 goto nla_put_failure;
449 
450         nla_nest_end(skb, nest_parms);
451         return 0;
452 
453 nla_put_failure:
454         return -1;
455 }
456 
457 static int
458 nfnl_cthelper_dump_policy(struct sk_buff *skb,
459                         struct nf_conntrack_helper *helper)
460 {
461         int i;
462         struct nlattr *nest_parms1, *nest_parms2;
463 
464         nest_parms1 = nla_nest_start(skb, NFCTH_POLICY | NLA_F_NESTED);
465         if (nest_parms1 == NULL)
466                 goto nla_put_failure;
467 
468         if (nla_put_be32(skb, NFCTH_POLICY_SET_NUM,
469                          htonl(helper->expect_class_max + 1)))
470                 goto nla_put_failure;
471 
472         for (i = 0; i < helper->expect_class_max + 1; i++) {
473                 nest_parms2 = nla_nest_start(skb,
474                                 (NFCTH_POLICY_SET+i) | NLA_F_NESTED);
475                 if (nest_parms2 == NULL)
476                         goto nla_put_failure;
477 
478                 if (nla_put_string(skb, NFCTH_POLICY_NAME,
479                                    helper->expect_policy[i].name))
480                         goto nla_put_failure;
481 
482                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_MAX,
483                                  htonl(helper->expect_policy[i].max_expected)))
484                         goto nla_put_failure;
485 
486                 if (nla_put_be32(skb, NFCTH_POLICY_EXPECT_TIMEOUT,
487                                  htonl(helper->expect_policy[i].timeout)))
488                         goto nla_put_failure;
489 
490                 nla_nest_end(skb, nest_parms2);
491         }
492         nla_nest_end(skb, nest_parms1);
493         return 0;
494 
495 nla_put_failure:
496         return -1;
497 }
498 
499 static int
500 nfnl_cthelper_fill_info(struct sk_buff *skb, u32 portid, u32 seq, u32 type,
501                         int event, struct nf_conntrack_helper *helper)
502 {
503         struct nlmsghdr *nlh;
504         struct nfgenmsg *nfmsg;
505         unsigned int flags = portid ? NLM_F_MULTI : 0;
506         int status;
507 
508         event |= NFNL_SUBSYS_CTHELPER << 8;
509         nlh = nlmsg_put(skb, portid, seq, event, sizeof(*nfmsg), flags);
510         if (nlh == NULL)
511                 goto nlmsg_failure;
512 
513         nfmsg = nlmsg_data(nlh);
514         nfmsg->nfgen_family = AF_UNSPEC;
515         nfmsg->version = NFNETLINK_V0;
516         nfmsg->res_id = 0;
517 
518         if (nla_put_string(skb, NFCTH_NAME, helper->name))
519                 goto nla_put_failure;
520 
521         if (nla_put_be32(skb, NFCTH_QUEUE_NUM, htonl(helper->queue_num)))
522                 goto nla_put_failure;
523 
524         if (nfnl_cthelper_dump_tuple(skb, helper) < 0)
525                 goto nla_put_failure;
526 
527         if (nfnl_cthelper_dump_policy(skb, helper) < 0)
528                 goto nla_put_failure;
529 
530         if (nla_put_be32(skb, NFCTH_PRIV_DATA_LEN, htonl(helper->data_len)))
531                 goto nla_put_failure;
532 
533         if (helper->flags & NF_CT_HELPER_F_CONFIGURED)
534                 status = NFCT_HELPER_STATUS_ENABLED;
535         else
536                 status = NFCT_HELPER_STATUS_DISABLED;
537 
538         if (nla_put_be32(skb, NFCTH_STATUS, htonl(status)))
539                 goto nla_put_failure;
540 
541         nlmsg_end(skb, nlh);
542         return skb->len;
543 
544 nlmsg_failure:
545 nla_put_failure:
546         nlmsg_cancel(skb, nlh);
547         return -1;
548 }
549 
550 static int
551 nfnl_cthelper_dump_table(struct sk_buff *skb, struct netlink_callback *cb)
552 {
553         struct nf_conntrack_helper *cur, *last;
554 
555         rcu_read_lock();
556         last = (struct nf_conntrack_helper *)cb->args[1];
557         for (; cb->args[0] < nf_ct_helper_hsize; cb->args[0]++) {
558 restart:
559                 hlist_for_each_entry_rcu(cur,
560                                 &nf_ct_helper_hash[cb->args[0]], hnode) {
561 
562                         /* skip non-userspace conntrack helpers. */
563                         if (!(cur->flags & NF_CT_HELPER_F_USERSPACE))
564                                 continue;
565 
566                         if (cb->args[1]) {
567                                 if (cur != last)
568                                         continue;
569                                 cb->args[1] = 0;
570                         }
571                         if (nfnl_cthelper_fill_info(skb,
572                                             NETLINK_CB(cb->skb).portid,
573                                             cb->nlh->nlmsg_seq,
574                                             NFNL_MSG_TYPE(cb->nlh->nlmsg_type),
575                                             NFNL_MSG_CTHELPER_NEW, cur) < 0) {
576                                 cb->args[1] = (unsigned long)cur;
577                                 goto out;
578                         }
579                 }
580         }
581         if (cb->args[1]) {
582                 cb->args[1] = 0;
583                 goto restart;
584         }
585 out:
586         rcu_read_unlock();
587         return skb->len;
588 }
589 
590 static int
591 nfnl_cthelper_get(struct sock *nfnl, struct sk_buff *skb,
592                   const struct nlmsghdr *nlh, const struct nlattr * const tb[])
593 {
594         int ret = -ENOENT;
595         struct nf_conntrack_helper *cur;
596         struct sk_buff *skb2;
597         char *helper_name = NULL;
598         struct nf_conntrack_tuple tuple;
599         struct nfnl_cthelper *nlcth;
600         bool tuple_set = false;
601 
602         if (!capable(CAP_NET_ADMIN))
603                 return -EPERM;
604 
605         if (nlh->nlmsg_flags & NLM_F_DUMP) {
606                 struct netlink_dump_control c = {
607                         .dump = nfnl_cthelper_dump_table,
608                 };
609                 return netlink_dump_start(nfnl, skb, nlh, &c);
610         }
611 
612         if (tb[NFCTH_NAME])
613                 helper_name = nla_data(tb[NFCTH_NAME]);
614 
615         if (tb[NFCTH_TUPLE]) {
616                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
617                 if (ret < 0)
618                         return ret;
619 
620                 tuple_set = true;
621         }
622 
623         list_for_each_entry(nlcth, &nfnl_cthelper_list, list) {
624                 cur = &nlcth->helper;
625                 if (helper_name &&
626                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
627                         continue;
628 
629                 if (tuple_set &&
630                     (tuple.src.l3num != cur->tuple.src.l3num ||
631                      tuple.dst.protonum != cur->tuple.dst.protonum))
632                         continue;
633 
634                 skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
635                 if (skb2 == NULL) {
636                         ret = -ENOMEM;
637                         break;
638                 }
639 
640                 ret = nfnl_cthelper_fill_info(skb2, NETLINK_CB(skb).portid,
641                                               nlh->nlmsg_seq,
642                                               NFNL_MSG_TYPE(nlh->nlmsg_type),
643                                               NFNL_MSG_CTHELPER_NEW, cur);
644                 if (ret <= 0) {
645                         kfree_skb(skb2);
646                         break;
647                 }
648 
649                 ret = netlink_unicast(nfnl, skb2, NETLINK_CB(skb).portid,
650                                       MSG_DONTWAIT);
651                 if (ret > 0)
652                         ret = 0;
653 
654                 /* this avoids a loop in nfnetlink. */
655                 return ret == -EAGAIN ? -ENOBUFS : ret;
656         }
657         return ret;
658 }
659 
660 static int
661 nfnl_cthelper_del(struct sock *nfnl, struct sk_buff *skb,
662              const struct nlmsghdr *nlh, const struct nlattr * const tb[])
663 {
664         char *helper_name = NULL;
665         struct nf_conntrack_helper *cur;
666         struct nf_conntrack_tuple tuple;
667         bool tuple_set = false, found = false;
668         struct nfnl_cthelper *nlcth, *n;
669         int j = 0, ret;
670 
671         if (!capable(CAP_NET_ADMIN))
672                 return -EPERM;
673 
674         if (tb[NFCTH_NAME])
675                 helper_name = nla_data(tb[NFCTH_NAME]);
676 
677         if (tb[NFCTH_TUPLE]) {
678                 ret = nfnl_cthelper_parse_tuple(&tuple, tb[NFCTH_TUPLE]);
679                 if (ret < 0)
680                         return ret;
681 
682                 tuple_set = true;
683         }
684 
685         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
686                 cur = &nlcth->helper;
687                 j++;
688 
689                 if (helper_name &&
690                     strncmp(cur->name, helper_name, NF_CT_HELPER_NAME_LEN))
691                         continue;
692 
693                 if (tuple_set &&
694                     (tuple.src.l3num != cur->tuple.src.l3num ||
695                      tuple.dst.protonum != cur->tuple.dst.protonum))
696                         continue;
697 
698                 found = true;
699                 nf_conntrack_helper_unregister(cur);
700                 kfree(cur->expect_policy);
701 
702                 list_del(&nlcth->list);
703                 kfree(nlcth);
704         }
705 
706         /* Make sure we return success if we flush and there is no helpers */
707         return (found || j == 0) ? 0 : -ENOENT;
708 }
709 
710 static const struct nla_policy nfnl_cthelper_policy[NFCTH_MAX+1] = {
711         [NFCTH_NAME] = { .type = NLA_NUL_STRING,
712                          .len = NF_CT_HELPER_NAME_LEN-1 },
713         [NFCTH_QUEUE_NUM] = { .type = NLA_U32, },
714 };
715 
716 static const struct nfnl_callback nfnl_cthelper_cb[NFNL_MSG_CTHELPER_MAX] = {
717         [NFNL_MSG_CTHELPER_NEW]         = { .call = nfnl_cthelper_new,
718                                             .attr_count = NFCTH_MAX,
719                                             .policy = nfnl_cthelper_policy },
720         [NFNL_MSG_CTHELPER_GET]         = { .call = nfnl_cthelper_get,
721                                             .attr_count = NFCTH_MAX,
722                                             .policy = nfnl_cthelper_policy },
723         [NFNL_MSG_CTHELPER_DEL]         = { .call = nfnl_cthelper_del,
724                                             .attr_count = NFCTH_MAX,
725                                             .policy = nfnl_cthelper_policy },
726 };
727 
728 static const struct nfnetlink_subsystem nfnl_cthelper_subsys = {
729         .name                           = "cthelper",
730         .subsys_id                      = NFNL_SUBSYS_CTHELPER,
731         .cb_count                       = NFNL_MSG_CTHELPER_MAX,
732         .cb                             = nfnl_cthelper_cb,
733 };
734 
735 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_CTHELPER);
736 
737 static int __init nfnl_cthelper_init(void)
738 {
739         int ret;
740 
741         ret = nfnetlink_subsys_register(&nfnl_cthelper_subsys);
742         if (ret < 0) {
743                 pr_err("nfnl_cthelper: cannot register with nfnetlink.\n");
744                 goto err_out;
745         }
746         return 0;
747 err_out:
748         return ret;
749 }
750 
751 static void __exit nfnl_cthelper_exit(void)
752 {
753         struct nf_conntrack_helper *cur;
754         struct nfnl_cthelper *nlcth, *n;
755 
756         nfnetlink_subsys_unregister(&nfnl_cthelper_subsys);
757 
758         list_for_each_entry_safe(nlcth, n, &nfnl_cthelper_list, list) {
759                 cur = &nlcth->helper;
760 
761                 nf_conntrack_helper_unregister(cur);
762                 kfree(cur->expect_policy);
763                 kfree(nlcth);
764         }
765 }
766 
767 module_init(nfnl_cthelper_init);
768 module_exit(nfnl_cthelper_exit);
769 

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