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                         return;
  88
  89                 int i = countExt.get(them);
  90                 if (i)
  91                         countExt.set(them, i - 1);
  92
  93                 // The DNSBL reply must contain an A result.
  94                 const DNS::ResourceRecord* const ans_record = r->FindAnswerOfType(DNS::QUERY_A);
  95                 if (!ans_record)
  96                 {
  97                         ConfEntry->stats_errors++;
  98                         ServerInstance->SNO->WriteGlobalSno('d', "%s returned an result with no IPv4 address.",
  99                                 ConfEntry->name.c_str());
 100                         return;
 101                 }
 102
 103                 // The DNSBL reply must be a valid IPv4 address.
 104                 in_addr resultip;
 105                 if (inet_pton(AF_INET, ans_record->rdata.c_str(), &resultip) != 1)
 106                 {
 107                         ConfEntry->stats_errors++;
 108                         ServerInstance->SNO->WriteGlobalSno('d', "%s returned an invalid IPv4 address: %s",
 109                                 ConfEntry->name.c_str(), ans_record->rdata.c_str());
 110                         return;
 111                 }
 112
 113                 // The DNSBL reply should be in the 127.0.0.0/8 range.
 114                 if ((resultip.s_addr & 0xFF) != 127)
 115                 {
 116                         ConfEntry->stats_errors++;
 117                         ServerInstance->SNO->WriteGlobalSno('d', "%s returned an IPv4 address which is outside of the 127.0.0.0/8 subnet: %s",
 118                                 ConfEntry->name.c_str(), ans_record->rdata.c_str());
 119                         return;
 120                 }
 121
 122                 bool match = false;
 123                 unsigned int result = 0;
 124                 switch (ConfEntry->type)
 125                 {
 126                         case DNSBLConfEntry::A_BITMASK:
 127                         {
 128                                 result = (resultip.s_addr >> 24) & ConfEntry->bitmask;
 129                                 match = (result != 0);
 130                                 break;
 131                         }
 132                         case DNSBLConfEntry::A_RECORD:
 133                         {
 134                                 result = resultip.s_addr >> 24;
 135                                 match = (ConfEntry->records[result] == 1);
 136                                 break;
 137                         }
 138                 }
 139
 140                 if (match)
 141                 {
 142                         std::string reason = ConfEntry->reason;
 143                         std::string::size_type x = reason.find("%ip%");
 144                         while (x != std::string::npos)
 145                         {
 146                                 reason.erase(x, 4);
 147                                 reason.insert(x, them->GetIPString());
 148                                 x = reason.find("%ip%");
 149                         }
 150
 151                         ConfEntry->stats_hits++;
 152
 153                         switch (ConfEntry->banaction)
 154                         {
 155                                 case DNSBLConfEntry::I_KILL:
 156                                 {
 157                                         ServerInstance->Users->QuitUser(them, "Killed (" + reason + ")");
 158                                         break;
 159                                 }
 160                                 case DNSBLConfEntry::I_MARK:
 161                                 {
 162                                         if (!ConfEntry->ident.empty())
 163                                         {
 164                                                 them->WriteNotice("Your ident has been set to " + ConfEntry->ident + " because you matched " + reason);
 165                                                 them->ChangeIdent(ConfEntry->ident);
 166                                         }
 167
 168                                         if (!ConfEntry->host.empty())
 169                                         {
 170                                                 them->WriteNotice("Your host has been set to " + ConfEntry->host + " because you matched " + reason);
 171                                                 them->ChangeDisplayedHost(ConfEntry->host);
 172                                         }
 173
 174                                         nameExt.set(them, ConfEntry->name);
 175                                         break;
 176                                 }
 177                                 case DNSBLConfEntry::I_KLINE:
 178                                 {
 179                                         KLine* kl = new KLine(ServerInstance->Time(), ConfEntry->duration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
 180                                                         "*", them->GetIPString());
 181                                         if (ServerInstance->XLines->AddLine(kl,NULL))
 182                                         {
 183                                                 ServerInstance->SNO->WriteToSnoMask('x', "K-line added due to DNSBL match on *@%s to expire in %s (on %s): %s",
 184                                                         them->GetIPString().c_str(), InspIRCd::DurationString(kl->duration).c_str(),
 185                                                         InspIRCd::TimeString(kl->expiry).c_str(), reason.c_str());
 186                                                 ServerInstance->XLines->ApplyLines();
 187                                         }
 188                                         else
 189                                         {
 190                                                 delete kl;
 191                                                 return;
 192                                         }
 193                                         break;
 194                                 }
 195                                 case DNSBLConfEntry::I_GLINE:
 196                                 {
 197                                         GLine* gl = new GLine(ServerInstance->Time(), ConfEntry->duration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
 198                                                         "*", them->GetIPString());
 199                                         if (ServerInstance->XLines->AddLine(gl,NULL))
 200                                         {
 201                                                 ServerInstance->SNO->WriteToSnoMask('x', "G-line added due to DNSBL match on *@%s to expire in %s (on %s): %s",
 202                                                         them->GetIPString().c_str(), InspIRCd::DurationString(gl->duration).c_str(),
 203                                                         InspIRCd::TimeString(gl->expiry).c_str(), reason.c_str());
 204                                                 ServerInstance->XLines->ApplyLines();
 205                                         }
 206                                         else
 207                                         {
 208                                                 delete gl;
 209                                                 return;
 210                                         }
 211                                         break;
 212                                 }
 213                                 case DNSBLConfEntry::I_ZLINE:
 214                                 {
 215                                         ZLine* zl = new ZLine(ServerInstance->Time(), ConfEntry->duration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
 216                                                         them->GetIPString());
 217                                         if (ServerInstance->XLines->AddLine(zl,NULL))
 218                                         {
 219                                                 ServerInstance->SNO->WriteToSnoMask('x', "Z-line added due to DNSBL match on %s to expire in %s (on %s): %s",
 220                                                         them->GetIPString().c_str(), InspIRCd::DurationString(zl->duration).c_str(),
 221                                                         InspIRCd::TimeString(zl->expiry).c_str(), reason.c_str());
 222                                                 ServerInstance->XLines->ApplyLines();
 223                                         }
 224                                         else
 225                                         {
 226                                                 delete zl;
 227                                                 return;
 228                                         }
 229                                         break;
 230                                 }
 231                                 case DNSBLConfEntry::I_UNKNOWN:
 232                                 default:
 233                                         break;
 234                         }
 235
 236                         ServerInstance->SNO->WriteGlobalSno('d', "Connecting user %s (%s) detected as being on the '%s' DNS blacklist with result %d",
 237                                 them->GetFullRealHost().c_str(), them->GetIPString().c_str(), ConfEntry->name.c_str(), result);
 238                 }
 239                 else
 240                         ConfEntry->stats_misses++;
 241         }
 242
 243         void OnError(const DNS::Query *q) CXX11_OVERRIDE
 244         {
 245                 LocalUser* them = IS_LOCAL(ServerInstance->FindUUID(theiruid));
 246                 if (!them || them->client_sa != theirsa)
 247                         return;
 248
 249                 int i = countExt.get(them);
 250                 if (i)
 251                         countExt.set(them, i - 1);
 252
 253                 if (q->error == DNS::ERROR_NO_RECORDS || q->error == DNS::ERROR_DOMAIN_NOT_FOUND)
 254                 {
 255                         ConfEntry->stats_misses++;
 256                         return;
 257                 }
 258
 259                 ConfEntry->stats_errors++;
 260                 ServerInstance->SNO->WriteGlobalSno('d', "An error occurred whilst checking whether %s (%s) is on the '%s' DNS blacklist: %s",
 261                         them->GetFullRealHost().c_str(), them->GetIPString().c_str(), ConfEntry->name.c_str(), this->manager->GetErrorStr(q->error).c_str());
 262         }
 263 };
 264
 265 typedef std::vector<reference<DNSBLConfEntry> > DNSBLConfList;
 266
 267 class ModuleDNSBL : public Module, public Stats::EventListener
 268 {
 269         DNSBLConfList DNSBLConfEntries;
 270         dynamic_reference<DNS::Manager> DNS;
 271         LocalStringExt nameExt;
 272         LocalIntExt countExt;
 273
 274         /*
 275          *      Convert a string to EnumBanaction
 276          */
 277         DNSBLConfEntry::EnumBanaction str2banaction(const std::string &action)
 278         {
 279                 if (stdalgo::string::equalsci(action, "kill"))
 280                         return DNSBLConfEntry::I_KILL;
 281                 if (stdalgo::string::equalsci(action, "kline"))
 282                         return DNSBLConfEntry::I_KLINE;
 283                 if (stdalgo::string::equalsci(action, "zline"))
 284                         return DNSBLConfEntry::I_ZLINE;
 285                 if (stdalgo::string::equalsci(action, "gline"))
 286                         return DNSBLConfEntry::I_GLINE;
 287                 if (stdalgo::string::equalsci(action, "mark"))
 288                         return DNSBLConfEntry::I_MARK;
 289                 return DNSBLConfEntry::I_UNKNOWN;
 290         }
 291  public:
 292         ModuleDNSBL()
 293                 : Stats::EventListener(this)
 294                 , DNS(this, "DNS")
 295                 , nameExt("dnsbl_match", ExtensionItem::EXT_USER, this)
 296                 , countExt("dnsbl_pending", ExtensionItem::EXT_USER, this)
 297         {
 298         }
 299
 300         void init() CXX11_OVERRIDE
 301         {
 302                 ServerInstance->SNO->EnableSnomask('d', "DNSBL");
 303         }
 304
 305         void Prioritize() CXX11_OVERRIDE
 306         {
 307                 Module* corexline = ServerInstance->Modules->Find("core_xline");
 308                 ServerInstance->Modules->SetPriority(this, I_OnSetUserIP, PRIORITY_AFTER, corexline);
 309         }
 310
 311         Version GetVersion() CXX11_OVERRIDE
 312         {
 313                 return Version("Allows the server administrator to check the IP address of connecting users against a DNSBL.", VF_VENDOR);
 314         }
 315
 316         /** Fill our conf vector with data
 317          */
 318         void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
 319         {
 320                 DNSBLConfList newentries;
 321
 322                 ConfigTagList dnsbls = ServerInstance->Config->ConfTags("dnsbl");
 323                 for(ConfigIter i = dnsbls.first; i != dnsbls.second; ++i)
 324                 {
 325                         ConfigTag* tag = i->second;
 326                         reference<DNSBLConfEntry> e = new DNSBLConfEntry();
 327
 328                         e->name = tag->getString("name");
 329                         e->ident = tag->getString("ident");
 330                         e->host = tag->getString("host");
 331                         e->reason = tag->getString("reason", "Your IP has been blacklisted.", 1);
 332                         e->domain = tag->getString("domain");
 333
 334                         if (stdalgo::string::equalsci(tag->getString("type"), "bitmask"))
 335                         {
 336                                 e->type = DNSBLConfEntry::A_BITMASK;
 337                                 e->bitmask = tag->getUInt("bitmask", 0, 0, UINT_MAX);
 338                         }
 339                         else
 340                         {
 341                                 memset(e->records, 0, sizeof(e->records));
 342                                 e->type = DNSBLConfEntry::A_RECORD;
 343                                 irc::portparser portrange(tag->getString("records"), false);
 344                                 long item = -1;
 345                                 while ((item = portrange.GetToken()))
 346                                         e->records[item] = 1;
 347                         }
 348
 349                         e->banaction = str2banaction(tag->getString("action"));
 350                         e->duration = tag->getDuration("duration", 60, 1);
 351
 352                         /* Use portparser for record replies */
 353
 354                         /* yeah, logic here is a little messy */
 355                         if ((e->bitmask <= 0) && (DNSBLConfEntry::A_BITMASK == e->type))
 356                         {
 357                                 throw ModuleException("Invalid <dnsbl:bitmask> at " + tag->getTagLocation());
 358                         }
 359                         else if (e->name.empty())
 360                         {
 361                                 throw ModuleException("Empty <dnsbl:name> at " + tag->getTagLocation());
 362                         }
 363                         else if (e->domain.empty())
 364                         {
 365                                 throw ModuleException("Empty <dnsbl:domain> at " + tag->getTagLocation());
 366                         }
 367                         else if (e->banaction == DNSBLConfEntry::I_UNKNOWN)
 368                         {
 369                                 throw ModuleException("Unknown <dnsbl:action> at " + tag->getTagLocation());
 370                         }
 371                         else
 372                         {
 373                                 /* add it, all is ok */
 374                                 newentries.push_back(e);
 375                         }
 376                 }
 377
 378                 DNSBLConfEntries.swap(newentries);
 379         }
 380
 381         void OnSetUserIP(LocalUser* user) CXX11_OVERRIDE
 382         {
 383                 if (user->exempt || user->quitting || !DNS)
 384                         return;
 385
 386                 // Clients can't be in a DNSBL if they aren't connected via IPv4 or IPv6.
 387                 if (user->client_sa.family() != AF_INET && user->client_sa.family() != AF_INET6)
 388                         return;
 389
 390                 if (user->MyClass)
 391                 {
 392                         if (!user->MyClass->config->getBool("usednsbl", true))
 393                                 return;
 394                 }
 395                 else
 396                 {
 397                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "User has no connect class in OnSetUserIP");
 398                         return;
 399                 }
 400
 401                 std::string reversedip;
 402                 if (user->client_sa.family() == AF_INET)
 403                 {
 404                         unsigned int a, b, c, d;
 405                         d = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 24) & 0xFF;
 406                         c = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 16) & 0xFF;
 407                         b = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 8) & 0xFF;
 408                         a = (unsigned int) user->client_sa.in4.sin_addr.s_addr & 0xFF;
 409
 410                         reversedip = ConvToStr(d) + "." + ConvToStr(c) + "." + ConvToStr(b) + "." + ConvToStr(a);
 411                 }
 412                 else if (user->client_sa.family() == AF_INET6)
 413                 {
 414                         const unsigned char* ip = user->client_sa.in6.sin6_addr.s6_addr;
 415
 416                         std::string buf = BinToHex(ip, 16);
 417                         for (std::string::const_reverse_iterator it = buf.rbegin(); it != buf.rend(); ++it)
 418                         {
 419                                 reversedip.push_back(*it);
 420                                 reversedip.push_back('.');
 421                         }
 422                         reversedip.erase(reversedip.length() - 1, 1);
 423                 }
 424                 else
 425                         return;
 426
 427                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Reversed IP %s -> %s", user->GetIPString().c_str(), reversedip.c_str());
 428
 429                 countExt.set(user, DNSBLConfEntries.size());
 430
 431                 // For each DNSBL, we will run through this lookup
 432                 for (unsigned i = 0; i < DNSBLConfEntries.size(); ++i)
 433                 {
 434                         // Fill hostname with a dnsbl style host (d.c.b.a.domain.tld)
 435                         std::string hostname = reversedip + "." + DNSBLConfEntries[i]->domain;
 436
 437                         /* now we'd need to fire off lookups for `hostname'. */
 438                         DNSBLResolver *r = new DNSBLResolver(*this->DNS, this, nameExt, countExt, hostname, user, DNSBLConfEntries[i]);
 439                         try
 440                         {
 441                                 this->DNS->Process(r);
 442                         }
 443                         catch (DNS::Exception &ex)
 444                         {
 445                                 delete r;
 446                                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, ex.GetReason());
 447                         }
 448
 449                         if (user->quitting)
 450                                 break;
 451                 }
 452         }
 453
 454         ModResult OnSetConnectClass(LocalUser* user, ConnectClass* myclass) CXX11_OVERRIDE
 455         {
 456                 std::string dnsbl;
 457                 if (!myclass->config->readString("dnsbl", dnsbl))
 458                         return MOD_RES_PASSTHRU;
 459
 460                 std::string* match = nameExt.get(user);
 461                 if (!match)
 462                 {
 463                         ServerInstance->Logs->Log("CONNECTCLASS", LOG_DEBUG, "The %s connect class is not suitable as it requires a DNSBL mark",
 464                                         myclass->GetName().c_str());
 465                         return MOD_RES_DENY;
 466                 }
 467
 468                 if (!InspIRCd::Match(*match, dnsbl))
 469                 {
 470                         ServerInstance->Logs->Log("CONNECTCLASS", LOG_DEBUG, "The %s connect class is not suitable as the DNSBL mark (%s) does not match %s",
 471                                         myclass->GetName().c_str(), match->c_str(), dnsbl.c_str());
 472                         return MOD_RES_DENY;
 473                 }
 474
 475                 return MOD_RES_PASSTHRU;
 476         }
 477
 478         ModResult OnCheckReady(LocalUser *user) CXX11_OVERRIDE
 479         {
 480                 if (countExt.get(user))
 481                         return MOD_RES_DENY;
 482                 return MOD_RES_PASSTHRU;
 483         }
 484
 485         ModResult OnStats(Stats::Context& stats) CXX11_OVERRIDE
 486         {
 487                 if (stats.GetSymbol() != 'd')
 488                         return MOD_RES_PASSTHRU;
 489
 490                 unsigned long total_hits = 0;
 491                 unsigned long total_misses = 0;
 492                 unsigned long total_errors = 0;
 493                 for (std::vector<reference<DNSBLConfEntry> >::const_iterator i = DNSBLConfEntries.begin(); i != DNSBLConfEntries.end(); ++i)
 494                 {
 495                         total_hits += (*i)->stats_hits;
 496                         total_misses += (*i)->stats_misses;
 497                         total_errors += (*i)->stats_errors;
 498
 499                         stats.AddRow(304, InspIRCd::Format("DNSBLSTATS \"%s\" had %lu hits, %lu misses, and %lu errors",
 500                                 (*i)->name.c_str(), (*i)->stats_hits, (*i)->stats_misses, (*i)->stats_errors));
 501                 }
 502
 503                 stats.AddRow(304, "DNSBLSTATS Total hits: " + ConvToStr(total_hits));
 504                 stats.AddRow(304, "DNSBLSTATS Total misses: " + ConvToStr(total_misses));
 505                 stats.AddRow(304, "DNSBLSTATS Total errors: " + ConvToStr(total_errors));
 506                 return MOD_RES_PASSTHRU;
 507         }
 508 };
 509
 510 MODULE_INIT(ModuleDNSBL)