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 "provider.h"
  42 #include "notice.h"
  43 #include "stdinc.h"
  44 #include "dns.h"
  45
  46 typedef enum filter_t
  47 {
  48         FILTER_ALL = 1,
  49         FILTER_LAST = 2,
  50 } filter_t;
  51
  52 /* Blacklist accepted IP types */
  53 #define IPTYPE_IPV4     1
  54 #define IPTYPE_IPV6     2
  55
  56 /* A configured DNSBL */
  57 struct blacklist
  58 {
  59         char host[IRCD_RES_HOSTLEN + 1];
  60         char reason[BUFSIZE];           /* Reason template (ircd fills in the blanks) */
  61         unsigned char iptype;           /* IP types supported */
  62         rb_dlink_list filters;          /* Filters for queries */
  63
  64         bool delete;                    /* If true delete when no clients */
  65         int refcount;                   /* When 0 and delete is set, remove this blacklist */
  66
  67         time_t lastwarning;             /* Last warning about garbage replies sent */
  68 };
  69
  70 /* A lookup in progress for a particular DNSBL for a particular client */
  71 struct blacklist_lookup
  72 {
  73         struct blacklist *bl;           /* Blacklist we're checking */
  74         struct auth_client *auth;       /* Client */
  75         struct dns_query *query;        /* DNS query pointer */
  76
  77         rb_dlink_node node;
  78 };
  79
  80 /* A blacklist filter */
  81 struct blacklist_filter
  82 {
  83         filter_t type;                  /* Type of filter */
  84         char filter[HOSTIPLEN]; /* The filter itself */
  85
  86         rb_dlink_node node;
  87 };
  88
  89 /* Blacklist user data attached to auth_client instance */
  90 struct blacklist_user
  91 {
  92         rb_dlink_list queries;          /* Blacklist queries in flight */
  93         time_t timeout;                 /* When this times out */
  94 };
  95
  96 /* public interfaces */
  97 static bool blacklists_init(void);
  98 static void blacklists_destroy(void);
  99
 100 static bool blacklists_start(struct auth_client *);
 101 static void blacklists_cancel(struct auth_client *);
 102
 103 /* private interfaces */
 104 static void unref_blacklist(struct blacklist *);
 105 static struct blacklist *new_blacklist(const char *, const char *, unsigned char, rb_dlink_list *);
 106 static struct blacklist *find_blacklist(const char *);
 107 static bool blacklist_check_reply(struct blacklist_lookup *, const char *);
 108 static void blacklist_dns_callback(const char *, bool, query_type, void *);
 109 static void initiate_blacklist_dnsquery(struct blacklist *, struct auth_client *);
 110 static void timeout_blacklist_queries_event(void *);
 111
 112 /* Variables */
 113 static rb_dlink_list blacklist_list = { NULL, NULL, 0 };
 114 static struct ev_entry *timeout_ev;
 115 static EVH timeout_blacklists;
 116 static int blacklist_timeout = 15;
 117
 118 /* private interfaces */
 119
 120 static void
 121 unref_blacklist(struct blacklist *bl)
 122 {
 123         rb_dlink_node *ptr, *nptr;
 124
 125         bl->refcount--;
 126         if (bl->delete && bl->refcount <= 0)
 127         {
 128                 RB_DLINK_FOREACH_SAFE(ptr, nptr, bl->filters.head)
 129                 {
 130                         rb_dlinkDelete(ptr, &bl->filters);
 131                         rb_free(ptr);
 132                 }
 133
 134                 rb_dlinkFindDestroy(bl, &blacklist_list);
 135                 rb_free(bl);
 136         }
 137 }
 138
 139 static struct blacklist *
 140 new_blacklist(const char *name, const char *reason, unsigned char iptype, rb_dlink_list *filters)
 141 {
 142         struct blacklist *bl;
 143
 144         if (name == NULL || reason == NULL || iptype == 0)
 145                 return NULL;
 146
 147         if((bl = find_blacklist(name)) == NULL)
 148         {
 149                 bl = rb_malloc(sizeof(struct blacklist));
 150                 rb_dlinkAddAlloc(bl, &blacklist_list);
 151         }
 152         else
 153                 bl->delete = false;
 154
 155         rb_strlcpy(bl->host, name, IRCD_RES_HOSTLEN + 1);
 156         rb_strlcpy(bl->reason, reason, BUFSIZE);
 157         bl->iptype = iptype;
 158
 159         rb_dlinkMoveList(filters, &bl->filters);
 160
 161         bl->lastwarning = 0;
 162
 163         return bl;
 164 }
 165
 166 static struct blacklist *
 167 find_blacklist(const char *name)
 168 {
 169         rb_dlink_node *ptr;
 170
 171         RB_DLINK_FOREACH(ptr, blacklist_list.head)
 172         {
 173                 struct blacklist *bl = (struct blacklist *)ptr->data;
 174
 175                 if (!strcasecmp(bl->host, name))
 176                         return bl;
 177         }
 178
 179         return NULL;
 180 }
 181
 182 static inline bool
 183 blacklist_check_reply(struct blacklist_lookup *bllookup, const char *ipaddr)
 184 {
 185         struct blacklist *bl = bllookup->bl;
 186         const char *lastoctet;
 187         rb_dlink_node *ptr;
 188
 189         /* No filters and entry found - thus positive match */
 190         if (!rb_dlink_list_length(&bl->filters))
 191                 return true;
 192
 193         /* Below will prolly have to change if IPv6 address replies are sent back */
 194         if ((lastoctet = strrchr(ipaddr, '.')) == NULL || *(++lastoctet) == '\0')
 195                 goto blwarn;
 196
 197         RB_DLINK_FOREACH(ptr, bl->filters.head)
 198         {
 199                 struct blacklist_filter *filter = ptr->data;
 200                 const char *cmpstr;
 201
 202                 if (filter->type == FILTER_ALL)
 203                         cmpstr = ipaddr;
 204                 else if (filter->type == FILTER_LAST)
 205                         cmpstr = lastoctet;
 206                 else
 207                 {
 208                         warn_opers(L_CRIT, "BUG: Unknown blacklist filter type on blacklist %s: %d",
 209                                         bl->host, filter->type);
 210                         continue;
 211                 }
 212
 213                 if (strcmp(cmpstr, filter->filter) == 0)
 214                         /* Match! */
 215                         return true;
 216         }
 217
 218         return false;
 219 blwarn:
 220         if (bl->lastwarning + 3600 < rb_current_time())
 221         {
 222                 warn_opers(L_WARN, "Garbage/undecipherable reply received from blacklist %s (reply %s)",
 223                                 bl->host, ipaddr);
 224                 bl->lastwarning = rb_current_time();
 225         }
 226         return false;
 227 }
 228
 229 static void
 230 blacklist_dns_callback(const char *result, bool status, query_type type, void *data)
 231 {
 232         struct blacklist_lookup *bllookup = (struct blacklist_lookup *)data;
 233         struct blacklist_user *bluser;
 234         struct auth_client *auth;
 235
 236         if (bllookup == NULL || bllookup->auth == NULL)
 237                 return;
 238
 239         auth = bllookup->auth;
 240         bluser = auth->data[PROVIDER_BLACKLIST];
 241         if(bluser == NULL)
 242                 return;
 243
 244         if (result != NULL && status && blacklist_check_reply(bllookup, result))
 245         {
 246                 /* Match found, so proceed no further */
 247                 blacklists_cancel(auth);
 248                 reject_client(auth, PROVIDER_BLACKLIST, bllookup->bl->reason);
 249                 return;
 250         }
 251
 252         unref_blacklist(bllookup->bl);
 253         rb_dlinkDelete(&bllookup->node, &bluser->queries);
 254         rb_free(bllookup);
 255
 256         if(!rb_dlink_list_length(&bluser->queries))
 257         {
 258                 /* Done here */
 259                 provider_done(auth, PROVIDER_BLACKLIST);
 260                 rb_free(bluser);
 261                 auth->data[PROVIDER_BLACKLIST] = NULL;
 262         }
 263 }
 264
 265 static void
 266 initiate_blacklist_dnsquery(struct blacklist *bl, struct auth_client *auth)
 267 {
 268         struct blacklist_lookup *bllookup = rb_malloc(sizeof(struct blacklist_lookup));
 269         struct blacklist_user *bluser = auth->data[PROVIDER_BLACKLIST];
 270         char buf[IRCD_RES_HOSTLEN + 1];
 271         int aftype;
 272
 273         bllookup->bl = bl;
 274         bllookup->auth = auth;
 275
 276         aftype = GET_SS_FAMILY(&auth->c_addr);
 277         if((aftype == AF_INET && (bl->iptype & IPTYPE_IPV4) == 0) ||
 278                 (aftype == AF_INET6 && (bl->iptype & IPTYPE_IPV6) == 0))
 279                 /* Incorrect blacklist type for this IP... */
 280                 return;
 281
 282         build_rdns(buf, sizeof(buf), &auth->c_addr, bl->host);
 283
 284         bllookup->query = lookup_ip(buf, AF_INET, blacklist_dns_callback, bllookup);
 285
 286         rb_dlinkAdd(bllookup, &bllookup->node, &bluser->queries);
 287         bl->refcount++;
 288 }
 289
 290 /* Timeout outstanding queries */
 291 static void
 292 timeout_blacklist_queries_event(void *notused)
 293 {
 294         struct auth_client *auth;
 295         rb_dictionary_iter iter;
 296
 297         RB_DICTIONARY_FOREACH(auth, &iter, auth_clients)
 298         {
 299                 struct blacklist_user *bluser = auth->data[PROVIDER_BLACKLIST];
 300
 301                 if(bluser != NULL && bluser->timeout < rb_current_time())
 302                 {
 303                         blacklists_cancel(auth);
 304                         provider_done(auth, PROVIDER_BLACKLIST);
 305                 }
 306         }
 307 }
 308
 309 static inline void
 310 lookup_all_blacklists(struct auth_client *auth)
 311 {
 312         struct blacklist_user *bluser = auth->data[PROVIDER_BLACKLIST];
 313         rb_dlink_node *ptr;
 314
 315         RB_DLINK_FOREACH(ptr, blacklist_list.head)
 316         {
 317                 struct blacklist *bl = (struct blacklist *)ptr->data;
 318
 319                 if (!bl->delete)
 320                         initiate_blacklist_dnsquery(bl, auth);
 321         }
 322
 323         bluser->timeout = rb_current_time() + blacklist_timeout;
 324 }
 325
 326 /* public interfaces */
 327 static bool
 328 blacklists_start(struct auth_client *auth)
 329 {
 330         if(auth->data[PROVIDER_BLACKLIST] != NULL)
 331                 return true;
 332
 333         if(!rb_dlink_list_length(&blacklist_list))
 334                 /* Nothing to do... */
 335                 return true;
 336
 337         auth->data[PROVIDER_BLACKLIST] = rb_malloc(sizeof(struct blacklist_user));
 338
 339         if(is_provider_done(auth, PROVIDER_RDNS) && is_provider_done(auth, PROVIDER_IDENT))
 340                 /* This probably can't happen but let's handle this case anyway */
 341                 lookup_all_blacklists(auth);
 342
 343         set_provider_on(auth, PROVIDER_BLACKLIST);
 344         return true;
 345 }
 346
 347 /* This is called every time a provider is completed as long as we are marked not done */
 348 static void
 349 blacklists_initiate(struct auth_client *auth, provider_t provider)
 350 {
 351         struct blacklist_user *bluser = auth->data[PROVIDER_BLACKLIST];
 352
 353         lrb_assert(provider != PROVIDER_BLACKLIST);
 354         lrb_assert(!is_provider_done(auth, PROVIDER_BLACKLIST));
 355         lrb_assert(rb_dlink_list_length(&blacklist_list) > 0);
 356
 357         if(bluser == NULL || rb_dlink_list_length(&bluser->queries))
 358                 /* Nothing to do */
 359                 return;
 360         else if(!(is_provider_done(auth, PROVIDER_RDNS) && is_provider_done(auth, PROVIDER_IDENT)))
 361                 /* Don't start until we've completed these */
 362                 return;
 363         else
 364                 lookup_all_blacklists(auth);
 365 }
 366
 367 static void
 368 blacklists_cancel(struct auth_client *auth)
 369 {
 370         rb_dlink_node *ptr, *nptr;
 371         struct blacklist_user *bluser = auth->data[PROVIDER_BLACKLIST];
 372
 373         if(bluser == NULL)
 374                 return;
 375
 376         RB_DLINK_FOREACH_SAFE(ptr, nptr, bluser->queries.head)
 377         {
 378                 struct blacklist_lookup *bllookup = ptr->data;
 379                 rb_dlinkDelete(&bllookup->node, &bluser->queries);
 380                 unref_blacklist(bllookup->bl);
 381                 cancel_query(bllookup->query);
 382                 rb_free(bllookup);
 383         }
 384
 385         rb_free(bluser);
 386         auth->data[PROVIDER_BLACKLIST] = NULL;
 387 }
 388
 389 static bool
 390 blacklists_init(void)
 391 {
 392         timeout_ev = rb_event_addish("timeout_blacklist_queries_event", timeout_blacklist_queries_event, NULL, 1);
 393         return (timeout_ev != NULL);
 394 }
 395
 396 static void
 397 blacklists_destroy(void)
 398 {
 399         rb_dlink_node *ptr, *nptr;
 400         rb_dictionary_iter iter;
 401         struct blacklist *bl;
 402         struct auth_client *auth;
 403
 404         RB_DICTIONARY_FOREACH(auth, &iter, auth_clients)
 405         {
 406                 blacklists_cancel(auth);
 407         }
 408
 409         RB_DLINK_FOREACH_SAFE(ptr, nptr, blacklist_list.head)
 410         {
 411                 bl = ptr->data;
 412                 if (bl->refcount > 0)
 413                         bl->delete = true;
 414                 else
 415                 {
 416                         rb_free(ptr->data);
 417                         rb_dlinkDestroy(ptr, &blacklist_list);
 418                 }
 419         }
 420 }
 421
 422 static void
 423 add_conf_blacklist(const char *key, int parc, const char **parv)
 424 {
 425         rb_dlink_list filters;
 426         char *tmp, *elemlist = rb_strdup(parv[2]);
 427         unsigned char iptype;
 428
 429         for(char *elem = rb_strtok_r(elemlist, ",", &tmp); elem; elem = rb_strtok_r(NULL, ",", &tmp))
 430         {
 431                 struct blacklist_filter *filter = rb_malloc(sizeof(struct blacklist_filter));
 432                 int dot_c = 0;
 433                 filter_t type = FILTER_LAST;
 434                 bool valid = true;
 435
 436                 /* Check blacklist filter type and for validity */
 437                 for(char *c = elem; *c != '\0'; c++)
 438                 {
 439                         if(*c == '.')
 440                         {
 441                                 if(++dot_c > 3)
 442                                 {
 443                                         warn_opers(L_CRIT, "addr_conf_blacklist got a bad filter (too many octets)");
 444                                         valid = false;
 445                                         break;
 446                                 }
 447
 448                                 type = FILTER_ALL;
 449                         }
 450                         else if(!isdigit(*c))
 451                         {
 452                                 warn_opers(L_CRIT, "addr_conf_blacklist got a bad filter (invalid character in blacklist filter: %c)", *c);
 453                                 valid = false;
 454                                 break;
 455                         }
 456                 }
 457
 458                 if(valid && dot_c > 0 && dot_c < 3)
 459                 {
 460                         warn_opers(L_CRIT, "addr_conf_blacklist got a bad filter (insufficient octets)");
 461                         valid = false;
 462                 }
 463
 464                 if(!valid)
 465                 {
 466                         rb_free(filter);
 467                         continue;
 468                 }
 469
 470                 filter->type = type;
 471                 rb_strlcpy(filter->filter, elem, sizeof(filter->filter));
 472                 rb_dlinkAdd(filter, &filter->node, &filters);
 473         }
 474
 475         rb_free(elemlist);
 476
 477         iptype = atoi(parv[1]) & 0x3;
 478         if(new_blacklist(parv[0], parv[3], iptype, &filters) == NULL)
 479         {
 480                 rb_dlink_node *ptr, *nptr;
 481
 482                 warn_opers(L_CRIT, "addr_conf_blacklist got a malformed blacklist");
 483
 484                 RB_DLINK_FOREACH_SAFE(ptr, nptr, filters.head)
 485                 {
 486                         rb_free(ptr->data);
 487                         rb_dlinkDelete(ptr, &filters);
 488                 }
 489         }
 490 }
 491
 492 static void
 493 add_conf_blacklist_timeout(const char *key, int parc, const char **parv)
 494 {
 495         int timeout = atoi(parv[0]);
 496
 497         if(timeout < 0)
 498         {
 499                 warn_opers(L_CRIT, "BUG: timeout < 0 (value: %d)", timeout);
 500                 return;
 501         }
 502
 503         blacklist_timeout = timeout;
 504 }
 505
 506 struct auth_opts_handler blacklist_options[] =
 507 {
 508         { "rbl", 4, add_conf_blacklist },
 509         { "rbl_timeout", 1, add_conf_blacklist_timeout },
 510         { NULL, 0, NULL },
 511 };
 512
 513 struct auth_provider blacklist_provider =
 514 {
 515         .id = PROVIDER_BLACKLIST,
 516         .init = blacklists_init,
 517         .destroy = blacklists_destroy,
 518         .start = blacklists_start,
 519         .cancel = blacklists_cancel,
 520         .completed = blacklists_initiate,
 521         .opt_handlers = blacklist_options,
 522 };