authd/providers/blacklist.c

   1 /*
   2  * charybdis: A slightly useful ircd.
   3  * blacklist.c: Manages DNS blacklist entries and lookups
   4  *
   5  * Copyright (C) 2006-2011 charybdis development team
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions are
   9  * met:
  10  *
  11  * 1. Redistributions of source code must retain the above copyright notice,
  12  *    this list of conditions and the following disclaimer.
  13  *
  14  * 2. Redistributions in binary form must reproduce the above copyright
  15  *    notice, this list of conditions and the following disclaimer in the
  16  *    documentation and/or other materials provided with the distribution.
  17  *
  18  * 3. The name of the author may not be used to endorse or promote products
  19  *    derived from this software without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  22  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  23  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  24  * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
  25  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  26  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  27  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  29  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
  30  * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  31  * POSSIBILITY OF SUCH DAMAGE.
  32  */
  33
  34 /* Originally written for charybdis circa 2006 (by nenolod?).
  35  * Tweaked for authd. Some functions and structs renamed. Public/private
  36  * interfaces have been shifted around. Some code has been cleaned up too.
  37  * -- Elizafox 24 March 2016
  38  */
  39
  40 #include "authd.h"
  41 #include "defaults.h"
  42 #include "provider.h"
  43 #include "notice.h"
  44 #include "stdinc.h"
  45 #include "dns.h"
  46
  47 #define SELF_PID (blacklist_provider.id)
  48
  49 typedef enum filter_t
  50 {
  51         FILTER_ALL = 1,
  52         FILTER_LAST = 2,
  53 } filter_t;
  54
  55 /* Blacklist accepted IP types */
  56 #define IPTYPE_IPV4     1
  57 #define IPTYPE_IPV6     2
  58
  59 /* A configured DNSBL */
  60 struct blacklist
  61 {
  62         char host[IRCD_RES_HOSTLEN + 1];
  63         char reason[BUFSIZE];           /* Reason template (ircd fills in the blanks) */
  64         uint8_t iptype;                 /* IP types supported */
  65         rb_dlink_list filters;          /* Filters for queries */
  66
  67         bool delete;                    /* If true delete when no clients */
  68         int refcount;                   /* When 0 and delete is set, remove this blacklist */
  69         unsigned int hits;
  70
  71         time_t lastwarning;             /* Last warning about garbage replies sent */
  72 };
  73
  74 /* A lookup in progress for a particular DNSBL for a particular client */
  75 struct blacklist_lookup
  76 {
  77         struct blacklist *bl;           /* Blacklist we're checking */
  78         struct auth_client *auth;       /* Client */
  79         struct dns_query *query;        /* DNS query pointer */
  80
  81         rb_dlink_node node;
  82 };
  83
  84 /* A blacklist filter */
  85 struct blacklist_filter
  86 {
  87         filter_t type;                  /* Type of filter */
  88         char filter[HOSTIPLEN];         /* The filter itself */
  89
  90         rb_dlink_node node;
  91 };
  92
  93 /* Blacklist user data attached to auth_client instance */
  94 struct blacklist_user
  95 {
  96         bool started;
  97         rb_dlink_list queries;          /* Blacklist queries in flight */
  98 };
  99
 100 /* public interfaces */
 101 static void blacklists_destroy(void);
 102
 103 static bool blacklists_start(struct auth_client *);
 104 static inline void blacklists_generic_cancel(struct auth_client *, const char *);
 105 static void blacklists_timeout(struct auth_client *);
 106 static void blacklists_cancel(struct auth_client *);
 107 static void blacklists_cancel_none(struct auth_client *);
 108
 109 /* private interfaces */
 110 static void unref_blacklist(struct blacklist *);
 111 static struct blacklist *new_blacklist(const char *, const char *, uint8_t, rb_dlink_list *);
 112 static struct blacklist *find_blacklist(const char *);
 113 static bool blacklist_check_reply(struct blacklist_lookup *, const char *);
 114 static void blacklist_dns_callback(const char *, bool, query_type, void *);
 115 static void initiate_blacklist_dnsquery(struct blacklist *, struct auth_client *);
 116
 117 /* Variables */
 118 static rb_dlink_list blacklist_list = { NULL, NULL, 0 };
 119 static int blacklist_timeout = BLACKLIST_TIMEOUT_DEFAULT;
 120
 121 /* private interfaces */
 122
 123 static void
 124 unref_blacklist(struct blacklist *bl)
 125 {
 126         rb_dlink_node *ptr, *nptr;
 127
 128         bl->refcount--;
 129         if (bl->delete && bl->refcount <= 0)
 130         {
 131                 RB_DLINK_FOREACH_SAFE(ptr, nptr, bl->filters.head)
 132                 {
 133                         rb_dlinkDelete(ptr, &bl->filters);
 134                         rb_free(ptr);
 135                 }
 136
 137                 rb_dlinkFindDestroy(bl, &blacklist_list);
 138                 rb_free(bl);
 139         }
 140 }
 141
 142 static struct blacklist *
 143 new_blacklist(const char *name, const char *reason, uint8_t iptype, rb_dlink_list *filters)
 144 {
 145         struct blacklist *bl;
 146
 147         if (name == NULL || reason == NULL || iptype == 0)
 148                 return NULL;
 149
 150         if((bl = find_blacklist(name)) == NULL)
 151         {
 152                 bl = rb_malloc(sizeof(struct blacklist));
 153                 rb_dlinkAddAlloc(bl, &blacklist_list);
 154         }
 155         else
 156                 bl->delete = false;
 157
 158         rb_strlcpy(bl->host, name, IRCD_RES_HOSTLEN + 1);
 159         rb_strlcpy(bl->reason, reason, BUFSIZE);
 160         bl->iptype = iptype;
 161
 162         rb_dlinkMoveList(filters, &bl->filters);
 163
 164         bl->lastwarning = 0;
 165
 166         return bl;
 167 }
 168
 169 static struct blacklist *
 170 find_blacklist(const char *name)
 171 {
 172         rb_dlink_node *ptr;
 173
 174         RB_DLINK_FOREACH(ptr, blacklist_list.head)
 175         {
 176                 struct blacklist *bl = (struct blacklist *)ptr->data;
 177
 178                 if (!strcasecmp(bl->host, name))
 179                         return bl;
 180         }
 181
 182         return NULL;
 183 }
 184
 185 static inline bool
 186 blacklist_check_reply(struct blacklist_lookup *bllookup, const char *ipaddr)
 187 {
 188         struct blacklist *bl = bllookup->bl;
 189         const char *lastoctet;
 190         rb_dlink_node *ptr;
 191
 192         /* No filters and entry found - thus positive match */
 193         if (!rb_dlink_list_length(&bl->filters))
 194                 return true;
 195
 196         /* Below will prolly have to change if IPv6 address replies are sent back */
 197         if ((lastoctet = strrchr(ipaddr, '.')) == NULL || *(++lastoctet) == '\0')
 198                 goto blwarn;
 199
 200         RB_DLINK_FOREACH(ptr, bl->filters.head)
 201         {
 202                 struct blacklist_filter *filter = ptr->data;
 203                 const char *cmpstr;
 204
 205                 if (filter->type == FILTER_ALL)
 206                         cmpstr = ipaddr;
 207                 else if (filter->type == FILTER_LAST)
 208                         cmpstr = lastoctet;
 209                 else
 210                 {
 211                         warn_opers(L_CRIT, "Blacklist: Unknown blacklist filter type (host %s): %d",
 212                                         bl->host, filter->type);
 213                         exit(EX_PROVIDER_ERROR);
 214                 }
 215
 216                 if (strcmp(cmpstr, filter->filter) == 0)
 217                         /* Match! */
 218                         return true;
 219         }
 220
 221         return false;
 222 blwarn:
 223         if (bl->lastwarning + 3600 < rb_current_time())
 224         {
 225                 warn_opers(L_WARN, "Garbage/undecipherable reply received from blacklist %s (reply %s)",
 226                                 bl->host, ipaddr);
 227                 bl->lastwarning = rb_current_time();
 228         }
 229
 230         return false;
 231 }
 232
 233 static void
 234 blacklist_dns_callback(const char *result, bool status, query_type type, void *data)
 235 {
 236         struct blacklist_lookup *bllookup = (struct blacklist_lookup *)data;
 237         struct blacklist_user *bluser;
 238         struct blacklist *bl;
 239         struct auth_client *auth;
 240
 241         lrb_assert(bllookup != NULL);
 242         lrb_assert(bllookup->auth != NULL);
 243
 244         bl = bllookup->bl;
 245         auth = bllookup->auth;
 246
 247         if((bluser = get_provider_data(auth, SELF_PID)) == NULL)
 248                 return;
 249
 250         if (result != NULL && status && blacklist_check_reply(bllookup, result))
 251         {
 252                 /* Match found, so proceed no further */
 253                 bl->hits++;
 254                 reject_client(auth, SELF_PID, bl->host, bl->reason);
 255                 blacklists_cancel(auth);
 256                 return;
 257         }
 258
 259         unref_blacklist(bl);
 260         cancel_query(bllookup->query);  /* Ignore future responses */
 261         rb_dlinkDelete(&bllookup->node, &bluser->queries);
 262         rb_free(bllookup);
 263
 264         if(!rb_dlink_list_length(&bluser->queries))
 265         {
 266                 /* Done here */
 267                 notice_client(auth->cid, "*** IP not found in DNS blacklist%s",
 268                                 rb_dlink_list_length(&blacklist_list) > 1 ? "s" : "");
 269                 rb_free(bluser);
 270                 set_provider_data(auth, SELF_PID, NULL);
 271                 set_provider_timeout_absolute(auth, SELF_PID, 0);
 272                 provider_done(auth, SELF_PID);
 273
 274                 auth_client_unref(auth);
 275         }
 276 }
 277
 278 static void
 279 initiate_blacklist_dnsquery(struct blacklist *bl, struct auth_client *auth)
 280 {
 281         struct blacklist_lookup *bllookup = rb_malloc(sizeof(struct blacklist_lookup));
 282         struct blacklist_user *bluser = get_provider_data(auth, SELF_PID);
 283         char buf[IRCD_RES_HOSTLEN + 1];
 284         int aftype;
 285
 286         bllookup->bl = bl;
 287         bllookup->auth = auth;
 288
 289         aftype = GET_SS_FAMILY(&auth->c_addr);
 290         if((aftype == AF_INET && (bl->iptype & IPTYPE_IPV4) == 0) ||
 291                 (aftype == AF_INET6 && (bl->iptype & IPTYPE_IPV6) == 0))
 292                 /* Incorrect blacklist type for this IP... */
 293         {
 294                 rb_free(bllookup);
 295                 return;
 296         }
 297
 298         build_rdns(buf, sizeof(buf), &auth->c_addr, bl->host);
 299         bllookup->query = lookup_ip(buf, AF_INET, blacklist_dns_callback, bllookup);
 300
 301         rb_dlinkAdd(bllookup, &bllookup->node, &bluser->queries);
 302         bl->refcount++;
 303 }
 304
 305 static inline bool
 306 lookup_all_blacklists(struct auth_client *auth)
 307 {
 308         struct blacklist_user *bluser = get_provider_data(auth, SELF_PID);
 309         rb_dlink_node *ptr;
 310         int iptype;
 311
 312         if(GET_SS_FAMILY(&auth->c_addr) == AF_INET)
 313                 iptype = IPTYPE_IPV4;
 314         else if(GET_SS_FAMILY(&auth->c_addr) == AF_INET6)
 315                 iptype = IPTYPE_IPV6;
 316         else
 317                 return false;
 318
 319         bluser->started = true;
 320         notice_client(auth->cid, "*** Checking your IP against DNS blacklist%s",
 321                         rb_dlink_list_length(&blacklist_list) > 1 ? "s" : "");
 322
 323         RB_DLINK_FOREACH(ptr, blacklist_list.head)
 324         {
 325                 struct blacklist *bl = (struct blacklist *)ptr->data;
 326
 327                 if (!bl->delete && (bl->iptype & iptype))
 328                         initiate_blacklist_dnsquery(bl, auth);
 329         }
 330
 331         if(!rb_dlink_list_length(&bluser->queries))
 332                 /* None checked. */
 333                 return false;
 334
 335         set_provider_timeout_relative(auth, SELF_PID, blacklist_timeout);
 336
 337         return true;
 338 }
 339
 340 static inline void
 341 delete_blacklist(struct blacklist *bl)
 342 {
 343         if (bl->refcount > 0)
 344                 bl->delete = true;
 345         else
 346         {
 347                 rb_dlinkFindDestroy(bl, &blacklist_list);
 348                 rb_free(bl);
 349         }
 350 }
 351
 352 static void
 353 delete_all_blacklists(void)
 354 {
 355         rb_dlink_node *ptr, *nptr;
 356
 357         RB_DLINK_FOREACH_SAFE(ptr, nptr, blacklist_list.head)
 358         {
 359                 delete_blacklist(ptr->data);
 360         }
 361 }
 362
 363 /* public interfaces */
 364 static bool
 365 blacklists_start(struct auth_client *auth)
 366 {
 367         lrb_assert(get_provider_data(auth, SELF_PID) == NULL);
 368
 369         if (!rb_dlink_list_length(&blacklist_list)) {
 370                 /* Nothing to do... */
 371                 provider_done(auth, SELF_PID);
 372                 return true;
 373         }
 374
 375         auth_client_ref(auth);
 376
 377         set_provider_data(auth, SELF_PID, rb_malloc(sizeof(struct blacklist_user)));
 378
 379         if (run_after_provider(auth, "rdns") && run_after_provider(auth, "ident")) {
 380                 /* Start the lookup if ident and rdns are finished, or not loaded. */
 381                 if (!lookup_all_blacklists(auth)) {
 382                         blacklists_cancel_none(auth);
 383                         return true;
 384                 }
 385         }
 386
 387         return true;
 388 }
 389
 390 /* This is called every time a provider is completed as long as we are marked not done */
 391 static void
 392 blacklists_initiate(struct auth_client *auth, uint32_t provider)
 393 {
 394         struct blacklist_user *bluser = get_provider_data(auth, SELF_PID);
 395
 396         lrb_assert(provider != SELF_PID);
 397         lrb_assert(!is_provider_done(auth, SELF_PID));
 398         lrb_assert(rb_dlink_list_length(&blacklist_list) > 0);
 399
 400         if (bluser == NULL || bluser->started) {
 401                 /* Nothing to do */
 402                 return;
 403         } else if (run_after_provider(auth, "rdns") && run_after_provider(auth, "ident")) {
 404                 /* Start the lookup if ident and rdns are finished, or not loaded. */
 405                 if (!lookup_all_blacklists(auth)) {
 406                         blacklists_cancel_none(auth);
 407                 }
 408         }
 409 }
 410
 411 static inline void
 412 blacklists_generic_cancel(struct auth_client *auth, const char *message)
 413 {
 414         rb_dlink_node *ptr, *nptr;
 415         struct blacklist_user *bluser = get_provider_data(auth, SELF_PID);
 416
 417         if(bluser == NULL)
 418                 return;
 419
 420         if(rb_dlink_list_length(&bluser->queries))
 421         {
 422                 notice_client(auth->cid, message);
 423
 424                 RB_DLINK_FOREACH_SAFE(ptr, nptr, bluser->queries.head)
 425                 {
 426                         struct blacklist_lookup *bllookup = ptr->data;
 427
 428                         cancel_query(bllookup->query);
 429                         unref_blacklist(bllookup->bl);
 430
 431                         rb_dlinkDelete(&bllookup->node, &bluser->queries);
 432                         rb_free(bllookup);
 433                 }
 434         }
 435
 436         rb_free(bluser);
 437         set_provider_data(auth, SELF_PID, NULL);
 438         set_provider_timeout_absolute(auth, SELF_PID, 0);
 439         provider_done(auth, SELF_PID);
 440
 441         auth_client_unref(auth);
 442 }
 443
 444 static void
 445 blacklists_timeout(struct auth_client *auth)
 446 {
 447         blacklists_generic_cancel(auth, "*** No response from DNS blacklists");
 448 }
 449
 450 static void
 451 blacklists_cancel(struct auth_client *auth)
 452 {
 453         blacklists_generic_cancel(auth, "*** Aborting DNS blacklist checks");
 454 }
 455
 456 static void
 457 blacklists_cancel_none(struct auth_client *auth)
 458 {
 459         blacklists_generic_cancel(auth, "*** Could not check DNS blacklists");
 460 }
 461
 462 static void
 463 blacklists_destroy(void)
 464 {
 465         rb_dictionary_iter iter;
 466         struct auth_client *auth;
 467
 468         RB_DICTIONARY_FOREACH(auth, &iter, auth_clients)
 469         {
 470                 blacklists_cancel(auth);
 471                 /* auth is now invalid as we have no reference */
 472         }
 473
 474         delete_all_blacklists();
 475 }
 476
 477 static void
 478 add_conf_blacklist(const char *key, int parc, const char **parv)
 479 {
 480         rb_dlink_list filters = { NULL, NULL, 0 };
 481         char *tmp, *elemlist = rb_strdup(parv[2]);
 482         uint8_t iptype;
 483
 484         if(*elemlist == '*')
 485                 goto end;
 486
 487         for(char *elem = rb_strtok_r(elemlist, ",", &tmp); elem; elem = rb_strtok_r(NULL, ",", &tmp))
 488         {
 489                 struct blacklist_filter *filter = rb_malloc(sizeof(struct blacklist_filter));
 490                 int dot_c = 0;
 491                 filter_t type = FILTER_LAST;
 492
 493                 /* Check blacklist filter type and for validity */
 494                 for(char *c = elem; *c != '\0'; c++)
 495                 {
 496                         if(*c == '.')
 497                         {
 498                                 if(++dot_c > 3)
 499                                 {
 500                                         warn_opers(L_CRIT, "Blacklist: addr_conf_blacklist got a bad filter (too many octets)");
 501                                         exit(EX_PROVIDER_ERROR);
 502                                 }
 503
 504                                 type = FILTER_ALL;
 505                         }
 506                         else if(!isdigit(*c))
 507                         {
 508                                 warn_opers(L_CRIT, "Blacklist: addr_conf_blacklist got a bad filter (invalid character in blacklist filter: %c)",
 509                                                 *c);
 510                                 exit(EX_PROVIDER_ERROR);
 511                         }
 512                 }
 513
 514                 if(dot_c > 0 && dot_c < 3)
 515                 {
 516                         warn_opers(L_CRIT, "Blacklist: addr_conf_blacklist got a bad filter (insufficient octets)");
 517                         exit(EX_PROVIDER_ERROR);
 518                 }
 519
 520                 filter->type = type;
 521                 rb_strlcpy(filter->filter, elem, sizeof(filter->filter));
 522                 rb_dlinkAdd(filter, &filter->node, &filters);
 523         }
 524
 525 end:
 526         rb_free(elemlist);
 527
 528         iptype = atoi(parv[1]) & 0x3;
 529         if(new_blacklist(parv[0], parv[3], iptype, &filters) == NULL)
 530         {
 531                 warn_opers(L_CRIT, "Blacklist: addr_conf_blacklist got a malformed blacklist");
 532                 exit(EX_PROVIDER_ERROR);
 533         }
 534 }
 535
 536 static void
 537 del_conf_blacklist(const char *key, int parc, const char **parv)
 538 {
 539         struct blacklist *bl = find_blacklist(parv[0]);
 540         if(bl == NULL)
 541         {
 542                 /* Not fatal for now... */
 543                 warn_opers(L_WARN, "Blacklist: tried to remove nonexistent blacklist %s", parv[0]);
 544                 return;
 545         }
 546
 547         delete_blacklist(bl);
 548 }
 549
 550 static void
 551 del_conf_blacklist_all(const char *key, int parc, const char **parv)
 552 {
 553         delete_all_blacklists();
 554 }
 555
 556 static void
 557 add_conf_blacklist_timeout(const char *key, int parc, const char **parv)
 558 {
 559         int timeout = atoi(parv[0]);
 560
 561         if(timeout < 0)
 562         {
 563                 warn_opers(L_CRIT, "Blacklist: blacklist timeout < 0 (value: %d)", timeout);
 564                 exit(EX_PROVIDER_ERROR);
 565         }
 566
 567         blacklist_timeout = timeout;
 568 }
 569
 570 #if 0
 571 static void
 572 blacklist_stats(uint32_t rid, char letter)
 573 {
 574         rb_dlink_node *ptr;
 575
 576         RB_DLINK_FOREACH(ptr, blacklist_list.head)
 577         {
 578                 struct blacklist *bl = ptr->data;
 579
 580                 if(bl->delete)
 581                         continue;
 582
 583                 stats_result(rid, letter, "%s %hhu %u", bl->host, bl->iptype, bl->hits);
 584         }
 585
 586         stats_done(rid, letter);
 587 }
 588 #endif
 589
 590 struct auth_opts_handler blacklist_options[] =
 591 {
 592         { "rbl", 4, add_conf_blacklist },
 593         { "rbl_del", 1, del_conf_blacklist },
 594         { "rbl_del_all", 0, del_conf_blacklist_all },
 595         { "rbl_timeout", 1, add_conf_blacklist_timeout },
 596         { NULL, 0, NULL },
 597 };
 598
 599 struct auth_provider blacklist_provider =
 600 {
 601         .name = "blacklist",
 602         .letter = 'B',
 603         .destroy = blacklists_destroy,
 604         .start = blacklists_start,
 605         .cancel = blacklists_cancel,
 606         .timeout = blacklists_timeout,
 607         .completed = blacklists_initiate,
 608         .opt_handlers = blacklist_options,
 609         /* .stats_handler = { 'B', blacklist_stats }, */
 610 };