src/modules/m_dnsbl.cpp

   1 /*
   2  * InspIRCd -- Internet Relay Chat Daemon
   3  *
   4  *   Copyright (C) 2018-2020 Matt Schatz <genius3000@g3k.solutions>
   5  *   Copyright (C) 2018-2019 linuxdaemon <linuxdaemon.irc@gmail.com>
   6  *   Copyright (C) 2013, 2017-2021 Sadie Powell <sadie@witchery.services>
   7  *   Copyright (C) 2013, 2015-2016 Adam <Adam@anope.org>
   8  *   Copyright (C) 2012-2016 Attila Molnar <attilamolnar@hush.com>
   9  *   Copyright (C) 2012, 2018 Robby <robby@chatbelgie.be>
  10  *   Copyright (C) 2009-2010 Daniel De Graaf <danieldg@inspircd.org>
  11  *   Copyright (C) 2007, 2010 Craig Edwards <brain@inspircd.org>
  12  *   Copyright (C) 2007 Dennis Friis <peavey@inspircd.org>
  13  *   Copyright (C) 2006-2009 Robin Burchell <robin+git@viroteck.net>
  14  *
  15  * This file is part of InspIRCd.  InspIRCd is free software: you can
  16  * redistribute it and/or modify it under the terms of the GNU General Public
  17  * License as published by the Free Software Foundation, version 2.
  18  *
  19  * This program is distributed in the hope that it will be useful, but WITHOUT
  20  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
  21  * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
  22  * details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  26  */
  27
  28
  29 #include "inspircd.h"
  30 #include "xline.h"
  31 #include "modules/dns.h"
  32 #include "modules/stats.h"
  33
  34 /* Class holding data for a single entry */
  35 class DNSBLConfEntry : public refcountbase
  36 {
  37         public:
  38                 enum EnumBanaction { I_UNKNOWN, I_KILL, I_ZLINE, I_KLINE, I_GLINE, I_MARK };
  39                 enum EnumType { A_RECORD, A_BITMASK };
  40                 std::string name, ident, host, domain, reason;
  41                 EnumBanaction banaction;
  42                 EnumType type;
  43                 unsigned long duration;
  44                 unsigned int bitmask;
  45                 unsigned char records[256];
  46                 unsigned long stats_hits, stats_misses, stats_errors;
  47                 DNSBLConfEntry()
  48                         : type(A_BITMASK)
  49                         , duration(86400)
  50                         , bitmask(0)
  51                         , stats_hits(0)
  52                         , stats_misses(0)
  53                         , stats_errors(0)
  54                 {
  55                 }
  56 };
  57
  58
  59 /** Resolver for CGI:IRC hostnames encoded in ident/real name
  60  */
  61 class DNSBLResolver : public DNS::Request
  62 {
  63  private:
  64         irc::sockets::sockaddrs theirsa;
  65         std::string theiruid;
  66         LocalStringExt& nameExt;
  67         LocalIntExt& countExt;
  68         reference<DNSBLConfEntry> ConfEntry;
  69
  70  public:
  71         DNSBLResolver(DNS::Manager *mgr, Module *me, LocalStringExt& match, LocalIntExt& ctr, const std::string &hostname, LocalUser* u, reference<DNSBLConfEntry> conf)
  72                 : DNS::Request(mgr, me, hostname, DNS::QUERY_A, true)
  73                 , theirsa(u->client_sa)
  74                 , theiruid(u->uuid)
  75                 , nameExt(match)
  76                 , countExt(ctr)
  77                 , ConfEntry(conf)
  78         {
  79         }
  80
  81         /* Note: This may be called multiple times for multiple A record results */
  82         void OnLookupComplete(const DNS::Query *r) CXX11_OVERRIDE
  83         {
  84                 /* Check the user still exists */
  85                 LocalUser* them = IS_LOCAL(ServerInstance->FindUUID(theiruid));
  86                 if (!them || them->client_sa != theirsa)
  87                 {
  88                         ConfEntry->stats_misses++;
  89                         return;
  90                 }
  91
  92                 int i = countExt.get(them);
  93                 if (i)
  94                         countExt.set(them, i - 1);
  95
  96                 // The DNSBL reply must contain an A result.
  97                 const DNS::ResourceRecord* const ans_record = r->FindAnswerOfType(DNS::QUERY_A);
  98                 if (!ans_record)
  99                 {
 100                         ConfEntry->stats_errors++;
 101                         ServerInstance->SNO->WriteGlobalSno('d', "%s returned an result with no IPv4 address.",
 102                                 ConfEntry->name.c_str());
 103                         return;
 104                 }
 105
 106                 // The DNSBL reply must be a valid IPv4 address.
 107                 in_addr resultip;
 108                 if (inet_pton(AF_INET, ans_record->rdata.c_str(), &resultip) != 1)
 109                 {
 110                         ConfEntry->stats_errors++;
 111                         ServerInstance->SNO->WriteGlobalSno('d', "%s returned an invalid IPv4 address: %s",
 112                                 ConfEntry->name.c_str(), ans_record->rdata.c_str());
 113                         return;
 114                 }
 115
 116                 // The DNSBL reply should be in the 127.0.0.0/8 range.
 117                 if ((resultip.s_addr & 0xFF) != 127)
 118                 {
 119                         ConfEntry->stats_errors++;
 120                         ServerInstance->SNO->WriteGlobalSno('d', "%s returned an IPv4 address which is outside of the 127.0.0.0/8 subnet: %s",
 121                                 ConfEntry->name.c_str(), ans_record->rdata.c_str());
 122                         return;
 123                 }
 124
 125                 bool match = false;
 126                 unsigned int result = 0;
 127                 switch (ConfEntry->type)
 128                 {
 129                         case DNSBLConfEntry::A_BITMASK:
 130                         {
 131                                 result = (resultip.s_addr >> 24) & ConfEntry->bitmask;
 132                                 match = (result != 0);
 133                                 break;
 134                         }
 135                         case DNSBLConfEntry::A_RECORD:
 136                         {
 137                                 result = resultip.s_addr >> 24;
 138                                 match = (ConfEntry->records[result] == 1);
 139                                 break;
 140                         }
 141                 }
 142
 143                 if (match)
 144                 {
 145                         std::string reason = ConfEntry->reason;
 146                         std::string::size_type x = reason.find("%ip%");
 147                         while (x != std::string::npos)
 148                         {
 149                                 reason.erase(x, 4);
 150                                 reason.insert(x, them->GetIPString());
 151                                 x = reason.find("%ip%");
 152                         }
 153
 154                         ConfEntry->stats_hits++;
 155
 156                         switch (ConfEntry->banaction)
 157                         {
 158                                 case DNSBLConfEntry::I_KILL:
 159                                 {
 160                                         ServerInstance->Users->QuitUser(them, "Killed (" + reason + ")");
 161                                         break;
 162                                 }
 163                                 case DNSBLConfEntry::I_MARK:
 164                                 {
 165                                         if (!ConfEntry->ident.empty())
 166                                         {
 167                                                 them->WriteNotice("Your ident has been set to " + ConfEntry->ident + " because you matched " + reason);
 168                                                 them->ChangeIdent(ConfEntry->ident);
 169                                         }
 170
 171                                         if (!ConfEntry->host.empty())
 172                                         {
 173                                                 them->WriteNotice("Your host has been set to " + ConfEntry->host + " because you matched " + reason);
 174                                                 them->ChangeDisplayedHost(ConfEntry->host);
 175                                         }
 176
 177                                         nameExt.set(them, ConfEntry->name);
 178                                         break;
 179                                 }
 180                                 case DNSBLConfEntry::I_KLINE:
 181                                 {
 182                                         KLine* kl = new KLine(ServerInstance->Time(), ConfEntry->duration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
 183                                                         "*", them->GetIPString());
 184                                         if (ServerInstance->XLines->AddLine(kl,NULL))
 185                                         {
 186                                                 ServerInstance->SNO->WriteToSnoMask('x', "K-line added due to DNSBL match on *@%s to expire in %s (on %s): %s",
 187                                                         them->GetIPString().c_str(), InspIRCd::DurationString(kl->duration).c_str(),
 188                                                         InspIRCd::TimeString(kl->expiry).c_str(), reason.c_str());
 189                                                 ServerInstance->XLines->ApplyLines();
 190                                         }
 191                                         else
 192                                         {
 193                                                 delete kl;
 194                                                 return;
 195                                         }
 196                                         break;
 197                                 }
 198                                 case DNSBLConfEntry::I_GLINE:
 199                                 {
 200                                         GLine* gl = new GLine(ServerInstance->Time(), ConfEntry->duration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
 201                                                         "*", them->GetIPString());
 202                                         if (ServerInstance->XLines->AddLine(gl,NULL))
 203                                         {
 204                                                 ServerInstance->SNO->WriteToSnoMask('x', "G-line added due to DNSBL match on *@%s to expire in %s (on %s): %s",
 205                                                         them->GetIPString().c_str(), InspIRCd::DurationString(gl->duration).c_str(),
 206                                                         InspIRCd::TimeString(gl->expiry).c_str(), reason.c_str());
 207                                                 ServerInstance->XLines->ApplyLines();
 208                                         }
 209                                         else
 210                                         {
 211                                                 delete gl;
 212                                                 return;
 213                                         }
 214                                         break;
 215                                 }
 216                                 case DNSBLConfEntry::I_ZLINE:
 217                                 {
 218                                         ZLine* zl = new ZLine(ServerInstance->Time(), ConfEntry->duration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
 219                                                         them->GetIPString());
 220                                         if (ServerInstance->XLines->AddLine(zl,NULL))
 221                                         {
 222                                                 ServerInstance->SNO->WriteToSnoMask('x', "Z-line added due to DNSBL match on %s to expire in %s (on %s): %s",
 223                                                         them->GetIPString().c_str(), InspIRCd::DurationString(zl->duration).c_str(),
 224                                                         InspIRCd::TimeString(zl->expiry).c_str(), reason.c_str());
 225                                                 ServerInstance->XLines->ApplyLines();
 226                                         }
 227                                         else
 228                                         {
 229                                                 delete zl;
 230                                                 return;
 231                                         }
 232                                         break;
 233                                 }
 234                                 case DNSBLConfEntry::I_UNKNOWN:
 235                                 default:
 236                                         break;
 237                         }
 238
 239                         ServerInstance->SNO->WriteGlobalSno('d', "Connecting user %s (%s) detected as being on the '%s' DNS blacklist with result %d",
 240                                 them->GetFullRealHost().c_str(), them->GetIPString().c_str(), ConfEntry->name.c_str(), result);
 241                 }
 242                 else
 243                         ConfEntry->stats_misses++;
 244         }
 245
 246         void OnError(const DNS::Query *q) CXX11_OVERRIDE
 247         {
 248                 bool is_miss = true;
 249                 switch (q->error)
 250                 {
 251                         case DNS::ERROR_NO_RECORDS:
 252                         case DNS::ERROR_DOMAIN_NOT_FOUND:
 253                                 ConfEntry->stats_misses++;
 254                                 break;
 255
 256                         default:
 257                                 ConfEntry->stats_errors++;
 258                                 is_miss = false;
 259                                 break;
 260                 }
 261
 262                 LocalUser* them = IS_LOCAL(ServerInstance->FindUUID(theiruid));
 263                 if (!them || them->client_sa != theirsa)
 264                         return;
 265
 266                 int i = countExt.get(them);
 267                 if (i)
 268                         countExt.set(them, i - 1);
 269
 270                 if (is_miss)
 271                         return;
 272
 273                 ServerInstance->SNO->WriteGlobalSno('d', "An error occurred whilst checking whether %s (%s) is on the '%s' DNS blacklist: %s",
 274                         them->GetFullRealHost().c_str(), them->GetIPString().c_str(), ConfEntry->name.c_str(), this->manager->GetErrorStr(q->error).c_str());
 275         }
 276 };
 277
 278 typedef std::vector<reference<DNSBLConfEntry> > DNSBLConfList;
 279
 280 class ModuleDNSBL : public Module, public Stats::EventListener
 281 {
 282         DNSBLConfList DNSBLConfEntries;
 283         dynamic_reference<DNS::Manager> DNS;
 284         LocalStringExt nameExt;
 285         LocalIntExt countExt;
 286
 287         /*
 288          *      Convert a string to EnumBanaction
 289          */
 290         DNSBLConfEntry::EnumBanaction str2banaction(const std::string &action)
 291         {
 292                 if (stdalgo::string::equalsci(action, "kill"))
 293                         return DNSBLConfEntry::I_KILL;
 294                 if (stdalgo::string::equalsci(action, "kline"))
 295                         return DNSBLConfEntry::I_KLINE;
 296                 if (stdalgo::string::equalsci(action, "zline"))
 297                         return DNSBLConfEntry::I_ZLINE;
 298                 if (stdalgo::string::equalsci(action, "gline"))
 299                         return DNSBLConfEntry::I_GLINE;
 300                 if (stdalgo::string::equalsci(action, "mark"))
 301                         return DNSBLConfEntry::I_MARK;
 302                 return DNSBLConfEntry::I_UNKNOWN;
 303         }
 304  public:
 305         ModuleDNSBL()
 306                 : Stats::EventListener(this)
 307                 , DNS(this, "DNS")
 308                 , nameExt("dnsbl_match", ExtensionItem::EXT_USER, this)
 309                 , countExt("dnsbl_pending", ExtensionItem::EXT_USER, this)
 310         {
 311         }
 312
 313         void init() CXX11_OVERRIDE
 314         {
 315                 ServerInstance->SNO->EnableSnomask('d', "DNSBL");
 316         }
 317
 318         void Prioritize() CXX11_OVERRIDE
 319         {
 320                 Module* corexline = ServerInstance->Modules->Find("core_xline");
 321                 ServerInstance->Modules->SetPriority(this, I_OnSetUserIP, PRIORITY_AFTER, corexline);
 322         }
 323
 324         Version GetVersion() CXX11_OVERRIDE
 325         {
 326                 return Version("Allows the server administrator to check the IP address of connecting users against a DNSBL.", VF_VENDOR);
 327         }
 328
 329         /** Fill our conf vector with data
 330          */
 331         void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
 332         {
 333                 DNSBLConfList newentries;
 334
 335                 ConfigTagList dnsbls = ServerInstance->Config->ConfTags("dnsbl");
 336                 for(ConfigIter i = dnsbls.first; i != dnsbls.second; ++i)
 337                 {
 338                         ConfigTag* tag = i->second;
 339                         reference<DNSBLConfEntry> e = new DNSBLConfEntry();
 340
 341                         e->name = tag->getString("name");
 342                         e->ident = tag->getString("ident");
 343                         e->host = tag->getString("host");
 344                         e->reason = tag->getString("reason", "Your IP has been blacklisted.", 1);
 345                         e->domain = tag->getString("domain");
 346
 347                         if (stdalgo::string::equalsci(tag->getString("type"), "bitmask"))
 348                         {
 349                                 e->type = DNSBLConfEntry::A_BITMASK;
 350                                 e->bitmask = tag->getUInt("bitmask", 0, 0, UINT_MAX);
 351                         }
 352                         else
 353                         {
 354                                 memset(e->records, 0, sizeof(e->records));
 355                                 e->type = DNSBLConfEntry::A_RECORD;
 356                                 irc::portparser portrange(tag->getString("records"), false);
 357                                 long item = -1;
 358                                 while ((item = portrange.GetToken()))
 359                                         e->records[item] = 1;
 360                         }
 361
 362                         e->banaction = str2banaction(tag->getString("action"));
 363                         e->duration = tag->getDuration("duration", 60, 1);
 364
 365                         /* Use portparser for record replies */
 366
 367                         /* yeah, logic here is a little messy */
 368                         if ((e->bitmask <= 0) && (DNSBLConfEntry::A_BITMASK == e->type))
 369                         {
 370                                 throw ModuleException("Invalid <dnsbl:bitmask> at " + tag->getTagLocation());
 371                         }
 372                         else if (e->name.empty())
 373                         {
 374                                 throw ModuleException("Empty <dnsbl:name> at " + tag->getTagLocation());
 375                         }
 376                         else if (e->domain.empty())
 377                         {
 378                                 throw ModuleException("Empty <dnsbl:domain> at " + tag->getTagLocation());
 379                         }
 380                         else if (e->banaction == DNSBLConfEntry::I_UNKNOWN)
 381                         {
 382                                 throw ModuleException("Unknown <dnsbl:action> at " + tag->getTagLocation());
 383                         }
 384                         else
 385                         {
 386                                 /* add it, all is ok */
 387                                 newentries.push_back(e);
 388                         }
 389                 }
 390
 391                 DNSBLConfEntries.swap(newentries);
 392         }
 393
 394         void OnSetUserIP(LocalUser* user) CXX11_OVERRIDE
 395         {
 396                 if (user->exempt || user->quitting || !DNS)
 397                         return;
 398
 399                 // Clients can't be in a DNSBL if they aren't connected via IPv4 or IPv6.
 400                 if (user->client_sa.family() != AF_INET && user->client_sa.family() != AF_INET6)
 401                         return;
 402
 403                 if (user->MyClass)
 404                 {
 405                         if (!user->MyClass->config->getBool("usednsbl", true))
 406                                 return;
 407                 }
 408                 else
 409                 {
 410                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "User has no connect class in OnSetUserIP");
 411                         return;
 412                 }
 413
 414                 std::string reversedip;
 415                 if (user->client_sa.family() == AF_INET)
 416                 {
 417                         unsigned int a, b, c, d;
 418                         d = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 24) & 0xFF;
 419                         c = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 16) & 0xFF;
 420                         b = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 8) & 0xFF;
 421                         a = (unsigned int) user->client_sa.in4.sin_addr.s_addr & 0xFF;
 422
 423                         reversedip = ConvToStr(d) + "." + ConvToStr(c) + "." + ConvToStr(b) + "." + ConvToStr(a);
 424                 }
 425                 else if (user->client_sa.family() == AF_INET6)
 426                 {
 427                         const unsigned char* ip = user->client_sa.in6.sin6_addr.s6_addr;
 428
 429                         std::string buf = BinToHex(ip, 16);
 430                         for (std::string::const_reverse_iterator it = buf.rbegin(); it != buf.rend(); ++it)
 431                         {
 432                                 reversedip.push_back(*it);
 433                                 reversedip.push_back('.');
 434                         }
 435                         reversedip.erase(reversedip.length() - 1, 1);
 436                 }
 437                 else
 438                         return;
 439
 440                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Reversed IP %s -> %s", user->GetIPString().c_str(), reversedip.c_str());
 441
 442                 countExt.set(user, DNSBLConfEntries.size());
 443
 444                 // For each DNSBL, we will run through this lookup
 445                 for (unsigned i = 0; i < DNSBLConfEntries.size(); ++i)
 446                 {
 447                         // Fill hostname with a dnsbl style host (d.c.b.a.domain.tld)
 448                         std::string hostname = reversedip + "." + DNSBLConfEntries[i]->domain;
 449
 450                         /* now we'd need to fire off lookups for `hostname'. */
 451                         DNSBLResolver *r = new DNSBLResolver(*this->DNS, this, nameExt, countExt, hostname, user, DNSBLConfEntries[i]);
 452                         try
 453                         {
 454                                 this->DNS->Process(r);
 455                         }
 456                         catch (DNS::Exception &ex)
 457                         {
 458                                 delete r;
 459                                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, ex.GetReason());
 460                         }
 461
 462                         if (user->quitting)
 463                                 break;
 464                 }
 465         }
 466
 467         ModResult OnSetConnectClass(LocalUser* user, ConnectClass* myclass) CXX11_OVERRIDE
 468         {
 469                 std::string dnsbl;
 470                 if (!myclass->config->readString("dnsbl", dnsbl))
 471                         return MOD_RES_PASSTHRU;
 472
 473                 std::string* match = nameExt.get(user);
 474                 if (!match)
 475                 {
 476                         ServerInstance->Logs->Log("CONNECTCLASS", LOG_DEBUG, "The %s connect class is not suitable as it requires a DNSBL mark",
 477                                         myclass->GetName().c_str());
 478                         return MOD_RES_DENY;
 479                 }
 480
 481                 if (!InspIRCd::Match(*match, dnsbl))
 482                 {
 483                         ServerInstance->Logs->Log("CONNECTCLASS", LOG_DEBUG, "The %s connect class is not suitable as the DNSBL mark (%s) does not match %s",
 484                                         myclass->GetName().c_str(), match->c_str(), dnsbl.c_str());
 485                         return MOD_RES_DENY;
 486                 }
 487
 488                 return MOD_RES_PASSTHRU;
 489         }
 490
 491         ModResult OnCheckReady(LocalUser *user) CXX11_OVERRIDE
 492         {
 493                 if (countExt.get(user))
 494                         return MOD_RES_DENY;
 495                 return MOD_RES_PASSTHRU;
 496         }
 497
 498         ModResult OnStats(Stats::Context& stats) CXX11_OVERRIDE
 499         {
 500                 if (stats.GetSymbol() != 'd')
 501                         return MOD_RES_PASSTHRU;
 502
 503                 unsigned long total_hits = 0;
 504                 unsigned long total_misses = 0;
 505                 unsigned long total_errors = 0;
 506                 for (std::vector<reference<DNSBLConfEntry> >::const_iterator i = DNSBLConfEntries.begin(); i != DNSBLConfEntries.end(); ++i)
 507                 {
 508                         total_hits += (*i)->stats_hits;
 509                         total_misses += (*i)->stats_misses;
 510                         total_errors += (*i)->stats_errors;
 511
 512                         stats.AddRow(304, InspIRCd::Format("DNSBLSTATS \"%s\" had %lu hits, %lu misses, and %lu errors",
 513                                 (*i)->name.c_str(), (*i)->stats_hits, (*i)->stats_misses, (*i)->stats_errors));
 514                 }
 515
 516                 stats.AddRow(304, "DNSBLSTATS Total hits: " + ConvToStr(total_hits));
 517                 stats.AddRow(304, "DNSBLSTATS Total misses: " + ConvToStr(total_misses));
 518                 stats.AddRow(304, "DNSBLSTATS Total errors: " + ConvToStr(total_errors));
 519                 return MOD_RES_PASSTHRU;
 520         }
 521 };
 522
 523 MODULE_INIT(ModuleDNSBL)