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, 2016-2020 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;
  47                 DNSBLConfEntry(): type(A_BITMASK),duration(86400),bitmask(0),stats_hits(0), stats_misses(0) {}
  48 };
  49
  50
  51 /** Resolver for CGI:IRC hostnames encoded in ident/real name
  52  */
  53 class DNSBLResolver : public DNS::Request
  54 {
  55  private:
  56         irc::sockets::sockaddrs theirsa;
  57         std::string theiruid;
  58         LocalStringExt& nameExt;
  59         LocalIntExt& countExt;
  60         reference<DNSBLConfEntry> ConfEntry;
  61
  62  public:
  63         DNSBLResolver(DNS::Manager *mgr, Module *me, LocalStringExt& match, LocalIntExt& ctr, const std::string &hostname, LocalUser* u, reference<DNSBLConfEntry> conf)
  64                 : DNS::Request(mgr, me, hostname, DNS::QUERY_A, true)
  65                 , theirsa(u->client_sa)
  66                 , theiruid(u->uuid)
  67                 , nameExt(match)
  68                 , countExt(ctr)
  69                 , ConfEntry(conf)
  70         {
  71         }
  72
  73         /* Note: This may be called multiple times for multiple A record results */
  74         void OnLookupComplete(const DNS::Query *r) CXX11_OVERRIDE
  75         {
  76                 /* Check the user still exists */
  77                 LocalUser* them = IS_LOCAL(ServerInstance->FindUUID(theiruid));
  78                 if (!them || them->client_sa != theirsa)
  79                         return;
  80
  81                 const DNS::ResourceRecord* const ans_record = r->FindAnswerOfType(DNS::QUERY_A);
  82                 if (!ans_record)
  83                         return;
  84
  85                 // All replies should be in 127.0.0.0/8
  86                 if (ans_record->rdata.compare(0, 4, "127.") != 0)
  87                 {
  88                         ServerInstance->SNO->WriteGlobalSno('d', "DNSBL: %s returned address outside of acceptable subnet 127.0.0.0/8: %s", ConfEntry->domain.c_str(), ans_record->rdata.c_str());
  89                         ConfEntry->stats_misses++;
  90                         return;
  91                 }
  92
  93                 int i = countExt.get(them);
  94                 if (i)
  95                         countExt.set(them, i - 1);
  96
  97                 // Now we calculate the bitmask: 256*(256*(256*a+b)+c)+d
  98
  99                 unsigned int bitmask = 0, record = 0;
 100                 bool match = false;
 101                 in_addr resultip;
 102
 103                 inet_pton(AF_INET, ans_record->rdata.c_str(), &resultip);
 104
 105                 switch (ConfEntry->type)
 106                 {
 107                         case DNSBLConfEntry::A_BITMASK:
 108                                 bitmask = resultip.s_addr >> 24; /* Last octet (network byte order) */
 109                                 bitmask &= ConfEntry->bitmask;
 110                                 match = (bitmask != 0);
 111                         break;
 112                         case DNSBLConfEntry::A_RECORD:
 113                                 record = resultip.s_addr >> 24; /* Last octet */
 114                                 match = (ConfEntry->records[record] == 1);
 115                         break;
 116                 }
 117
 118                 if (match)
 119                 {
 120                         std::string reason = ConfEntry->reason;
 121                         std::string::size_type x = reason.find("%ip%");
 122                         while (x != std::string::npos)
 123                         {
 124                                 reason.erase(x, 4);
 125                                 reason.insert(x, them->GetIPString());
 126                                 x = reason.find("%ip%");
 127                         }
 128
 129                         ConfEntry->stats_hits++;
 130
 131                         switch (ConfEntry->banaction)
 132                         {
 133                                 case DNSBLConfEntry::I_KILL:
 134                                 {
 135                                         ServerInstance->Users->QuitUser(them, "Killed (" + reason + ")");
 136                                         break;
 137                                 }
 138                                 case DNSBLConfEntry::I_MARK:
 139                                 {
 140                                         if (!ConfEntry->ident.empty())
 141                                         {
 142                                                 them->WriteNotice("Your ident has been set to " + ConfEntry->ident + " because you matched " + reason);
 143                                                 them->ChangeIdent(ConfEntry->ident);
 144                                         }
 145
 146                                         if (!ConfEntry->host.empty())
 147                                         {
 148                                                 them->WriteNotice("Your host has been set to " + ConfEntry->host + " because you matched " + reason);
 149                                                 them->ChangeDisplayedHost(ConfEntry->host);
 150                                         }
 151
 152                                         nameExt.set(them, ConfEntry->name);
 153                                         break;
 154                                 }
 155                                 case DNSBLConfEntry::I_KLINE:
 156                                 {
 157                                         KLine* kl = new KLine(ServerInstance->Time(), ConfEntry->duration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
 158                                                         "*", them->GetIPString());
 159                                         if (ServerInstance->XLines->AddLine(kl,NULL))
 160                                         {
 161                                                 ServerInstance->SNO->WriteToSnoMask('x', "K-line added due to DNSBL match on *@%s to expire in %s (on %s): %s",
 162                                                         them->GetIPString().c_str(), InspIRCd::DurationString(kl->duration).c_str(),
 163                                                         InspIRCd::TimeString(kl->expiry).c_str(), reason.c_str());
 164                                                 ServerInstance->XLines->ApplyLines();
 165                                         }
 166                                         else
 167                                         {
 168                                                 delete kl;
 169                                                 return;
 170                                         }
 171                                         break;
 172                                 }
 173                                 case DNSBLConfEntry::I_GLINE:
 174                                 {
 175                                         GLine* gl = new GLine(ServerInstance->Time(), ConfEntry->duration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
 176                                                         "*", them->GetIPString());
 177                                         if (ServerInstance->XLines->AddLine(gl,NULL))
 178                                         {
 179                                                 ServerInstance->SNO->WriteToSnoMask('x', "G-line added due to DNSBL match on *@%s to expire in %s (on %s): %s",
 180                                                         them->GetIPString().c_str(), InspIRCd::DurationString(gl->duration).c_str(),
 181                                                         InspIRCd::TimeString(gl->expiry).c_str(), reason.c_str());
 182                                                 ServerInstance->XLines->ApplyLines();
 183                                         }
 184                                         else
 185                                         {
 186                                                 delete gl;
 187                                                 return;
 188                                         }
 189                                         break;
 190                                 }
 191                                 case DNSBLConfEntry::I_ZLINE:
 192                                 {
 193                                         ZLine* zl = new ZLine(ServerInstance->Time(), ConfEntry->duration, ServerInstance->Config->ServerName.c_str(), reason.c_str(),
 194                                                         them->GetIPString());
 195                                         if (ServerInstance->XLines->AddLine(zl,NULL))
 196                                         {
 197                                                 ServerInstance->SNO->WriteToSnoMask('x', "Z-line added due to DNSBL match on %s to expire in %s (on %s): %s",
 198                                                         them->GetIPString().c_str(), InspIRCd::DurationString(zl->duration).c_str(),
 199                                                         InspIRCd::TimeString(zl->expiry).c_str(), reason.c_str());
 200                                                 ServerInstance->XLines->ApplyLines();
 201                                         }
 202                                         else
 203                                         {
 204                                                 delete zl;
 205                                                 return;
 206                                         }
 207                                         break;
 208                                 }
 209                                 case DNSBLConfEntry::I_UNKNOWN:
 210                                 default:
 211                                         break;
 212                         }
 213
 214                         ServerInstance->SNO->WriteGlobalSno('d', "Connecting user %s (%s) detected as being on the '%s' DNS blacklist with result %d",
 215                                 them->GetFullRealHost().c_str(), them->GetIPString().c_str(), ConfEntry->name.c_str(), (ConfEntry->type==DNSBLConfEntry::A_BITMASK) ? bitmask : record);
 216                 }
 217                 else
 218                         ConfEntry->stats_misses++;
 219         }
 220
 221         void OnError(const DNS::Query *q) CXX11_OVERRIDE
 222         {
 223                 LocalUser* them = IS_LOCAL(ServerInstance->FindUUID(theiruid));
 224                 if (!them || them->client_sa != theirsa)
 225                         return;
 226
 227                 int i = countExt.get(them);
 228                 if (i)
 229                         countExt.set(them, i - 1);
 230
 231                 if (q->error == DNS::ERROR_NO_RECORDS || q->error == DNS::ERROR_DOMAIN_NOT_FOUND)
 232                 {
 233                         ConfEntry->stats_misses++;
 234                         return;
 235                 }
 236
 237                 ServerInstance->SNO->WriteGlobalSno('d', "An error occurred whilst checking whether %s (%s) is on the '%s' DNS blacklist: %s",
 238                         them->GetFullRealHost().c_str(), them->GetIPString().c_str(), ConfEntry->name.c_str(), this->manager->GetErrorStr(q->error).c_str());
 239         }
 240 };
 241
 242 typedef std::vector<reference<DNSBLConfEntry> > DNSBLConfList;
 243
 244 class ModuleDNSBL : public Module, public Stats::EventListener
 245 {
 246         DNSBLConfList DNSBLConfEntries;
 247         dynamic_reference<DNS::Manager> DNS;
 248         LocalStringExt nameExt;
 249         LocalIntExt countExt;
 250
 251         /*
 252          *      Convert a string to EnumBanaction
 253          */
 254         DNSBLConfEntry::EnumBanaction str2banaction(const std::string &action)
 255         {
 256                 if (stdalgo::string::equalsci(action, "kill"))
 257                         return DNSBLConfEntry::I_KILL;
 258                 if (stdalgo::string::equalsci(action, "kline"))
 259                         return DNSBLConfEntry::I_KLINE;
 260                 if (stdalgo::string::equalsci(action, "zline"))
 261                         return DNSBLConfEntry::I_ZLINE;
 262                 if (stdalgo::string::equalsci(action, "gline"))
 263                         return DNSBLConfEntry::I_GLINE;
 264                 if (stdalgo::string::equalsci(action, "mark"))
 265                         return DNSBLConfEntry::I_MARK;
 266                 return DNSBLConfEntry::I_UNKNOWN;
 267         }
 268  public:
 269         ModuleDNSBL()
 270                 : Stats::EventListener(this)
 271                 , DNS(this, "DNS")
 272                 , nameExt("dnsbl_match", ExtensionItem::EXT_USER, this)
 273                 , countExt("dnsbl_pending", ExtensionItem::EXT_USER, this)
 274         {
 275         }
 276
 277         void init() CXX11_OVERRIDE
 278         {
 279                 ServerInstance->SNO->EnableSnomask('d', "DNSBL");
 280         }
 281
 282         Version GetVersion() CXX11_OVERRIDE
 283         {
 284                 return Version("Allows the server administrator to check the IP address of connecting users against a DNSBL.", VF_VENDOR);
 285         }
 286
 287         /** Fill our conf vector with data
 288          */
 289         void ReadConfig(ConfigStatus& status) CXX11_OVERRIDE
 290         {
 291                 DNSBLConfList newentries;
 292
 293                 ConfigTagList dnsbls = ServerInstance->Config->ConfTags("dnsbl");
 294                 for(ConfigIter i = dnsbls.first; i != dnsbls.second; ++i)
 295                 {
 296                         ConfigTag* tag = i->second;
 297                         reference<DNSBLConfEntry> e = new DNSBLConfEntry();
 298
 299                         e->name = tag->getString("name");
 300                         e->ident = tag->getString("ident");
 301                         e->host = tag->getString("host");
 302                         e->reason = tag->getString("reason", "Your IP has been blacklisted.", 1);
 303                         e->domain = tag->getString("domain");
 304
 305                         if (stdalgo::string::equalsci(tag->getString("type"), "bitmask"))
 306                         {
 307                                 e->type = DNSBLConfEntry::A_BITMASK;
 308                                 e->bitmask = tag->getUInt("bitmask", 0, 0, UINT_MAX);
 309                         }
 310                         else
 311                         {
 312                                 memset(e->records, 0, sizeof(e->records));
 313                                 e->type = DNSBLConfEntry::A_RECORD;
 314                                 irc::portparser portrange(tag->getString("records"), false);
 315                                 long item = -1;
 316                                 while ((item = portrange.GetToken()))
 317                                         e->records[item] = 1;
 318                         }
 319
 320                         e->banaction = str2banaction(tag->getString("action"));
 321                         e->duration = tag->getDuration("duration", 60, 1);
 322
 323                         /* Use portparser for record replies */
 324
 325                         /* yeah, logic here is a little messy */
 326                         if ((e->bitmask <= 0) && (DNSBLConfEntry::A_BITMASK == e->type))
 327                         {
 328                                 throw ModuleException("Invalid <dnsbl:bitmask> at " + tag->getTagLocation());
 329                         }
 330                         else if (e->name.empty())
 331                         {
 332                                 throw ModuleException("Empty <dnsbl:name> at " + tag->getTagLocation());
 333                         }
 334                         else if (e->domain.empty())
 335                         {
 336                                 throw ModuleException("Empty <dnsbl:domain> at " + tag->getTagLocation());
 337                         }
 338                         else if (e->banaction == DNSBLConfEntry::I_UNKNOWN)
 339                         {
 340                                 throw ModuleException("Unknown <dnsbl:action> at " + tag->getTagLocation());
 341                         }
 342                         else
 343                         {
 344                                 /* add it, all is ok */
 345                                 newentries.push_back(e);
 346                         }
 347                 }
 348
 349                 DNSBLConfEntries.swap(newentries);
 350         }
 351
 352         void OnSetUserIP(LocalUser* user) CXX11_OVERRIDE
 353         {
 354                 if ((user->exempt) || !DNS)
 355                         return;
 356
 357                 // Clients can't be in a DNSBL if they aren't connected via IPv4 or IPv6.
 358                 if (user->client_sa.family() != AF_INET && user->client_sa.family() != AF_INET6)
 359                         return;
 360
 361                 if (user->MyClass)
 362                 {
 363                         if (!user->MyClass->config->getBool("usednsbl", true))
 364                                 return;
 365                 }
 366                 else
 367                         ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "User has no connect class in OnSetUserIP");
 368
 369                 std::string reversedip;
 370                 if (user->client_sa.family() == AF_INET)
 371                 {
 372                         unsigned int a, b, c, d;
 373                         d = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 24) & 0xFF;
 374                         c = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 16) & 0xFF;
 375                         b = (unsigned int) (user->client_sa.in4.sin_addr.s_addr >> 8) & 0xFF;
 376                         a = (unsigned int) user->client_sa.in4.sin_addr.s_addr & 0xFF;
 377
 378                         reversedip = ConvToStr(d) + "." + ConvToStr(c) + "." + ConvToStr(b) + "." + ConvToStr(a);
 379                 }
 380                 else if (user->client_sa.family() == AF_INET6)
 381                 {
 382                         const unsigned char* ip = user->client_sa.in6.sin6_addr.s6_addr;
 383
 384                         std::string buf = BinToHex(ip, 16);
 385                         for (std::string::const_reverse_iterator it = buf.rbegin(); it != buf.rend(); ++it)
 386                         {
 387                                 reversedip.push_back(*it);
 388                                 reversedip.push_back('.');
 389                         }
 390                         reversedip.erase(reversedip.length() - 1, 1);
 391                 }
 392                 else
 393                         return;
 394
 395                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, "Reversed IP %s -> %s", user->GetIPString().c_str(), reversedip.c_str());
 396
 397                 countExt.set(user, DNSBLConfEntries.size());
 398
 399                 // For each DNSBL, we will run through this lookup
 400                 for (unsigned i = 0; i < DNSBLConfEntries.size(); ++i)
 401                 {
 402                         // Fill hostname with a dnsbl style host (d.c.b.a.domain.tld)
 403                         std::string hostname = reversedip + "." + DNSBLConfEntries[i]->domain;
 404
 405                         /* now we'd need to fire off lookups for `hostname'. */
 406                         DNSBLResolver *r = new DNSBLResolver(*this->DNS, this, nameExt, countExt, hostname, user, DNSBLConfEntries[i]);
 407                         try
 408                         {
 409                                 this->DNS->Process(r);
 410                         }
 411                         catch (DNS::Exception &ex)
 412                         {
 413                                 delete r;
 414                                 ServerInstance->Logs->Log(MODNAME, LOG_DEBUG, ex.GetReason());
 415                         }
 416
 417                         if (user->quitting)
 418                                 break;
 419                 }
 420         }
 421
 422         ModResult OnSetConnectClass(LocalUser* user, ConnectClass* myclass) CXX11_OVERRIDE
 423         {
 424                 std::string dnsbl;
 425                 if (!myclass->config->readString("dnsbl", dnsbl))
 426                         return MOD_RES_PASSTHRU;
 427
 428                 std::string* match = nameExt.get(user);
 429                 if (!match)
 430                 {
 431                         ServerInstance->Logs->Log("CONNECTCLASS", LOG_DEBUG, "The %s connect class is not suitable as it requires a DNSBL mark",
 432                                         myclass->GetName().c_str());
 433                         return MOD_RES_DENY;
 434                 }
 435
 436                 if (!InspIRCd::Match(*match, dnsbl))
 437                 {
 438                         ServerInstance->Logs->Log("CONNECTCLASS", LOG_DEBUG, "The %s connect class is not suitable as the DNSBL mark (%s) does not match %s",
 439                                         myclass->GetName().c_str(), match->c_str(), dnsbl.c_str());
 440                         return MOD_RES_DENY;
 441                 }
 442
 443                 return MOD_RES_PASSTHRU;
 444         }
 445
 446         ModResult OnCheckReady(LocalUser *user) CXX11_OVERRIDE
 447         {
 448                 if (countExt.get(user))
 449                         return MOD_RES_DENY;
 450                 return MOD_RES_PASSTHRU;
 451         }
 452
 453         ModResult OnStats(Stats::Context& stats) CXX11_OVERRIDE
 454         {
 455                 if (stats.GetSymbol() != 'd')
 456                         return MOD_RES_PASSTHRU;
 457
 458                 unsigned long total_hits = 0, total_misses = 0;
 459
 460                 for (std::vector<reference<DNSBLConfEntry> >::const_iterator i = DNSBLConfEntries.begin(); i != DNSBLConfEntries.end(); ++i)
 461                 {
 462                         total_hits += (*i)->stats_hits;
 463                         total_misses += (*i)->stats_misses;
 464
 465                         stats.AddRow(304, "DNSBLSTATS DNSbl \"" + (*i)->name + "\" had " +
 466                                         ConvToStr((*i)->stats_hits) + " hits and " + ConvToStr((*i)->stats_misses) + " misses");
 467                 }
 468
 469                 stats.AddRow(304, "DNSBLSTATS Total hits: " + ConvToStr(total_hits));
 470                 stats.AddRow(304, "DNSBLSTATS Total misses: " + ConvToStr(total_misses));
 471
 472                 return MOD_RES_PASSTHRU;
 473         }
 474 };
 475
 476 MODULE_INIT(ModuleDNSBL)