src/modules/m_cloaking.cpp

   1 /*       +------------------------------------+
   2  *       | Inspire Internet Relay Chat Daemon |
   3  *       +------------------------------------+
   4  *
   5  *  InspIRCd: (C) 2002-2009 InspIRCd Development Team
   6  * See: http://wiki.inspircd.org/Credits
   7  *
   8  * This program is free but copyrighted software; see
   9  *          the file COPYING for details.
  10  *
  11  * ---------------------------------------------------
  12  */
  13
  14 #include "inspircd.h"
  15 #include "m_hash.h"
  16
  17 /* $ModDesc: Provides masking of user hostnames */
  18
  19 enum CloakMode
  20 {
  21         /** 1.2-compatible host-based cloak */
  22         MODE_COMPAT_HOST,
  23         /** 1.2-compatible IP-only cloak */
  24         MODE_COMPAT_IPONLY,
  25         /** 2.0 cloak of "half" of the hostname plus the full IP hash */
  26         MODE_HALF_CLOAK,
  27         /** 2.0 cloak of IP hash, split at 2 common CIDR range points */
  28         MODE_OPAQUE
  29 };
  30
  31 // lowercase-only encoding similar to base64, used for hash output
  32 static const char base32[] = "0123456789abcdefghijklmnopqrstuv";
  33
  34 /** Handles user mode +x
  35  */
  36 class CloakUser : public ModeHandler
  37 {
  38  public:
  39         LocalStringExt ext;
  40
  41         CloakUser(Module* source)
  42                 : ModeHandler(source, "cloak", 'x', PARAM_NONE, MODETYPE_USER),
  43                 ext("cloaked_host", source)
  44         {
  45         }
  46
  47         ModeAction OnModeChange(User* source, User* dest, Channel* channel, std::string &parameter, bool adding)
  48         {
  49                 /* For remote clients, we don't take any action, we just allow it.
  50                  * The local server where they are will set their cloak instead.
  51                  * This is fine, as we will receive it later.
  52                  */
  53                 if (!IS_LOCAL(dest))
  54                 {
  55                         dest->SetMode('x',adding);
  56                         return MODEACTION_ALLOW;
  57                 }
  58
  59                 /* don't allow this user to spam modechanges */
  60                 dest->IncreasePenalty(5);
  61
  62                 if (adding)
  63                 {
  64                         if(!dest->IsModeSet('x'))
  65                         {
  66                                 /* The mode is being turned on - so attempt to
  67                                  * allocate the user a cloaked host using a non-reversible
  68                                  * algorithm (its simple, but its non-reversible so the
  69                                  * simplicity doesnt really matter). This algorithm
  70                                  * will not work if the user has only one level of domain
  71                                  * naming in their hostname (e.g. if they are on a lan or
  72                                  * are connecting via localhost) -- this doesnt matter much.
  73                                  */
  74
  75                                 std::string* cloak = ext.get(dest);
  76
  77                                 if (!cloak)
  78                                 {
  79                                         /* Force creation of missing cloak */
  80                                         creator->OnUserConnect(dest);
  81                                         cloak = ext.get(dest);
  82                                 }
  83                                 if (cloak)
  84                                 {
  85                                         dest->ChangeDisplayedHost(cloak->c_str());
  86                                         dest->SetMode('x',true);
  87                                         return MODEACTION_ALLOW;
  88                                 }
  89                         }
  90                 }
  91                 else
  92                 {
  93                         if (dest->IsModeSet('x'))
  94                         {
  95                                 /* User is removing the mode, so just restore their real host
  96                                  * and make it match the displayed one.
  97                                  */
  98                                 dest->ChangeDisplayedHost(dest->host.c_str());
  99                                 dest->SetMode('x',false);
 100                                 return MODEACTION_ALLOW;
 101                         }
 102                 }
 103
 104                 return MODEACTION_DENY;
 105         }
 106
 107 };
 108
 109
 110 class ModuleCloaking : public Module
 111 {
 112  private:
 113         CloakUser cu;
 114         CloakMode mode;
 115         std::string prefix;
 116         std::string key;
 117         unsigned int compatkey[4];
 118         const char* xtab[4];
 119         Module* HashProvider;
 120
 121  public:
 122         ModuleCloaking() : cu(this)
 123         {
 124                 /* Attempt to locate the md5 service provider, bail if we can't find it */
 125                 HashProvider = ServerInstance->Modules->Find("m_md5.so");
 126                 if (!HashProvider)
 127                         throw ModuleException("Can't find m_md5.so. Please load m_md5.so before m_cloaking.so.");
 128
 129                 OnRehash(NULL);
 130
 131                 /* Register it with the core */
 132                 if (!ServerInstance->Modes->AddMode(&cu))
 133                         throw ModuleException("Could not add new modes!");
 134
 135                 ServerInstance->Modules->UseInterface("HashRequest");
 136                 ServerInstance->Extensions.Register(&cu.ext);
 137
 138                 Implementation eventlist[] = { I_OnRehash, I_OnCheckBan, I_OnUserConnect };
 139                 ServerInstance->Modules->Attach(eventlist, this, 3);
 140
 141                 CloakExistingUsers();
 142         }
 143
 144         /** This function takes a domain name string and returns just the last two domain parts,
 145          * or the last domain part if only two are available. Failing that it just returns what it was given.
 146          *
 147          * For example, if it is passed "svn.inspircd.org" it will return ".inspircd.org".
 148          * If it is passed "brainbox.winbot.co.uk" it will return ".co.uk",
 149          * and if it is passed "localhost.localdomain" it will return ".localdomain".
 150          *
 151          * This is used to ensure a significant part of the host is always cloaked (see Bug #216)
 152          */
 153         std::string LastTwoDomainParts(const std::string &host)
 154         {
 155                 int dots = 0;
 156                 std::string::size_type splitdot = host.length();
 157
 158                 for (std::string::size_type x = host.length() - 1; x; --x)
 159                 {
 160                         if (host[x] == '.')
 161                         {
 162                                 splitdot = x;
 163                                 dots++;
 164                         }
 165                         if (dots >= 3)
 166                                 break;
 167                 }
 168
 169                 if (splitdot == host.length())
 170                         return host;
 171                 else
 172                         return host.substr(splitdot);
 173         }
 174
 175         std::string CompatCloak4(const char* ip)
 176         {
 177                 irc::sepstream seps(ip, '.');
 178                 std::string octet[4];
 179                 int i[4];
 180
 181                 for (int j = 0; j < 4; j++)
 182                 {
 183                         seps.GetToken(octet[j]);
 184                         i[j] = atoi(octet[j].c_str());
 185                 }
 186
 187                 octet[3] = octet[0] + "." + octet[1] + "." + octet[2] + "." + octet[3];
 188                 octet[2] = octet[0] + "." + octet[1] + "." + octet[2];
 189                 octet[1] = octet[0] + "." + octet[1];
 190
 191                 /* Reset the Hash module and send it our IV */
 192
 193                 std::string rv;
 194
 195                 /* Send the Hash module a different hex table for each octet group's Hash sum */
 196                 for (int k = 0; k < 4; k++)
 197                 {
 198                         HashRequestIV hash(this, HashProvider, compatkey, xtab[(compatkey[k]+i[k]) % 4], octet[k]);
 199                         rv.append(hash.result.substr(0,6));
 200                         if (k < 3)
 201                                 rv.append(".");
 202                 }
 203                 /* Stick them all together */
 204                 return rv;
 205         }
 206
 207         std::string CompatCloak6(const char* ip)
 208         {
 209                 std::vector<std::string> hashies;
 210                 std::string item;
 211                 int rounds = 0;
 212
 213                 /* Reset the Hash module and send it our IV */
 214
 215                 for (const char* input = ip; *input; input++)
 216                 {
 217                         item += *input;
 218                         if (item.length() > 7)
 219                         {
 220                                 HashRequestIV hash(this, HashProvider, compatkey, xtab[(compatkey[1]+rounds) % 4], item);
 221                                 hashies.push_back(hash.result.substr(0,8));
 222                                 item.clear();
 223                         }
 224                         rounds++;
 225                 }
 226                 if (!item.empty())
 227                 {
 228                         HashRequestIV hash(this, HashProvider, compatkey, xtab[(compatkey[1]+rounds) % 4], item);
 229                         hashies.push_back(hash.result.substr(0,8));
 230                 }
 231                 /* Stick them all together */
 232                 return irc::stringjoiner(":", hashies, 0, hashies.size() - 1).GetJoined();
 233         }
 234
 235         std::string ReversePartialIP(const irc::sockets::sockaddrs& ip)
 236         {
 237                 char rv[50];
 238                 if (ip.sa.sa_family == AF_INET6)
 239                 {
 240                         snprintf(rv, 50, ".%02x%02x.%02x%02x.%02x%02x.IP",
 241                                 ip.in6.sin6_addr.s6_addr[4], ip.in6.sin6_addr.s6_addr[5],
 242                                 ip.in6.sin6_addr.s6_addr[2], ip.in6.sin6_addr.s6_addr[3],
 243                                 ip.in6.sin6_addr.s6_addr[0], ip.in6.sin6_addr.s6_addr[1]);
 244                 }
 245                 else
 246                 {
 247                         const unsigned char* ip4 = (const unsigned char*)&ip.in4.sin_addr;
 248                         snprintf(rv, 50, ".%d.%d.IP", ip4[1], ip4[0]);
 249                 }
 250                 return rv;
 251         }
 252
 253         std::string SegmentIP(const irc::sockets::sockaddrs& ip)
 254         {
 255                 std::string bindata;
 256                 int hop1, hop2;
 257                 if (ip.sa.sa_family == AF_INET6)
 258                 {
 259                         bindata = std::string((const char*)ip.in6.sin6_addr.s6_addr, 16);
 260                         hop1 = 8;
 261                         hop2 = 6;
 262                 }
 263                 else
 264                 {
 265                         bindata = std::string((const char*)&ip.in4.sin_addr, 4);
 266                         hop1 = 3;
 267                         hop2 = 2;
 268                 }
 269
 270                 std::string rv;
 271                 rv.reserve(prefix.length() + 30);
 272                 rv.append(prefix);
 273                 rv.append(SegmentCloak(bindata, 2));
 274                 rv.append(1, '.');
 275                 bindata.erase(hop1);
 276                 rv.append(SegmentCloak(bindata, 3));
 277                 rv.append(1, '.');
 278                 bindata.erase(hop2);
 279                 rv.append(SegmentCloak(bindata, 4));
 280                 rv.append(".IP");
 281                 return rv;
 282         }
 283
 284         std::string SegmentCloak(const std::string& item, char id)
 285         {
 286                 std::string input;
 287                 input.reserve(key.length() + 3 + item.length());
 288                 input.append(1, id);
 289                 input.append(key);
 290                 input.append(1, 0); // null does not terminate a C++ string
 291                 input.append(item);
 292
 293                 HashRequest hash(this, HashProvider, input);
 294                 std::string rv = hash.binresult.substr(0,6);
 295                 for(int i=0; i < 6; i++)
 296                 {
 297                         // this discards 3 bits per byte. We have an
 298                         // overabundance of bits in the hash output, doesn't
 299                         // matter which ones we are discarding.
 300                         rv[i] = base32[rv[i] & 0x1F];
 301                 }
 302                 return rv;
 303         }
 304
 305         void CloakExistingUsers()
 306         {
 307                 std::string* cloak;
 308                 for (std::vector<User*>::iterator u = ServerInstance->Users->local_users.begin(); u != ServerInstance->Users->local_users.end(); u++)
 309                 {
 310                         cloak = cu.ext.get(*u);
 311                         if (!cloak)
 312                         {
 313                                 OnUserConnect(*u);
 314                         }
 315                 }
 316         }
 317
 318         ModResult OnCheckBan(User* user, Channel* chan, const std::string& mask)
 319         {
 320                 char cmask[MAXBUF];
 321                 std::string* cloak = cu.ext.get(user);
 322                 /* Check if they have a cloaked host, but are not using it */
 323                 if (cloak && *cloak != user->dhost)
 324                 {
 325                         snprintf(cmask, MAXBUF, "%s!%s@%s", user->nick.c_str(), user->ident.c_str(), cloak->c_str());
 326                         if (InspIRCd::Match(cmask,mask))
 327                                 return MOD_RES_DENY;
 328                 }
 329                 return MOD_RES_PASSTHRU;
 330         }
 331
 332         void Prioritize()
 333         {
 334                 /* Needs to be after m_banexception etc. */
 335                 ServerInstance->Modules->SetPriority(this, I_OnCheckBan, PRIORITY_LAST);
 336         }
 337
 338         ~ModuleCloaking()
 339         {
 340                 ServerInstance->Modules->DoneWithInterface("HashRequest");
 341         }
 342
 343         Version GetVersion()
 344         {
 345                 // returns the version number of the module to be
 346                 // listed in /MODULES
 347                 return Version("Provides masking of user hostnames", VF_COMMON|VF_VENDOR,API_VERSION);
 348         }
 349
 350         void OnRehash(User* user)
 351         {
 352                 ConfigReader Conf;
 353                 prefix = Conf.ReadValue("cloak","prefix",0);
 354
 355                 std::string modestr = Conf.ReadValue("cloak", "mode", 0);
 356                 if (modestr == "compat-host")
 357                         mode = MODE_COMPAT_HOST;
 358                 else if (modestr == "compat-ip")
 359                         mode = MODE_COMPAT_IPONLY;
 360                 else if (modestr == "half")
 361                         mode = MODE_HALF_CLOAK;
 362                 else if (modestr == "full")
 363                         mode = MODE_OPAQUE;
 364                 else
 365                         throw ModuleException("Bad value for <cloak:mode>; must be one of compat-host, compat-ip, half, full");
 366
 367                 if (mode == MODE_COMPAT_HOST || mode == MODE_COMPAT_IPONLY)
 368                 {
 369                         bool lowercase = Conf.ReadFlag("cloak", "lowercase", 0);
 370
 371                         /* These are *not* using the need_positive parameter of ReadInteger -
 372                          * that will limit the valid values to only the positive values in a
 373                          * signed int. Instead, accept any value that fits into an int and
 374                          * cast it to an unsigned int. That will, a bit oddly, give us the full
 375                          * spectrum of an unsigned integer. - Special
 376                          *
 377                          * We must limit the keys or else we get different results on
 378                          * amd64/x86 boxes. - psychon */
 379                         const unsigned int limit = 0x80000000;
 380                         compatkey[1] = (unsigned int) Conf.ReadInteger("cloak","key1",0,false);
 381                         compatkey[2] = (unsigned int) Conf.ReadInteger("cloak","key2",0,false);
 382                         compatkey[3] = (unsigned int) Conf.ReadInteger("cloak","key3",0,false);
 383                         compatkey[4] = (unsigned int) Conf.ReadInteger("cloak","key4",0,false);
 384
 385                         if (!lowercase)
 386                         {
 387                                 xtab[0] = "F92E45D871BCA630";
 388                                 xtab[1] = "A1B9D80C72E653F4";
 389                                 xtab[2] = "1ABC078934DEF562";
 390                                 xtab[3] = "ABCDEF5678901234";
 391                         }
 392                         else
 393                         {
 394                                 xtab[0] = "f92e45d871bca630";
 395                                 xtab[1] = "a1b9d80c72e653f4";
 396                                 xtab[2] = "1abc078934def562";
 397                                 xtab[3] = "abcdef5678901234";
 398                         }
 399
 400                         if (prefix.empty())
 401                                 prefix = ServerInstance->Config->Network;
 402
 403                         if (!compatkey[1] || !compatkey[2] || !compatkey[3] || !compatkey[4] ||
 404                                 compatkey[1] >= limit || compatkey[2] >= limit || compatkey[3] >= limit || compatkey[4] >= limit)
 405                         {
 406                                 std::string detail;
 407                                 if (!compatkey[1] || compatkey[1] >= limit)
 408                                         detail = "<cloak:key1> is not valid, it may be set to a too high/low value, or it may not exist.";
 409                                 else if (!compatkey[2] || compatkey[2] >= limit)
 410                                         detail = "<cloak:key2> is not valid, it may be set to a too high/low value, or it may not exist.";
 411                                 else if (!compatkey[3] || compatkey[3] >= limit)
 412                                         detail = "<cloak:key3> is not valid, it may be set to a too high/low value, or it may not exist.";
 413                                 else if (!compatkey[4] || compatkey[4] >= limit)
 414                                         detail = "<cloak:key4> is not valid, it may be set to a too high/low value, or it may not exist.";
 415
 416                                 throw ModuleException("You have not defined cloak keys for m_cloaking!!! THIS IS INSECURE AND SHOULD BE CHECKED! - " + detail);
 417                         }
 418                 }
 419                 else
 420                 {
 421                         key = Conf.ReadFlag("cloak", "key", 0);
 422                         if (key.empty() || key == "secret")
 423                                 throw ModuleException("You have not defined cloak keys for m_cloaking. Define <cloak:key> as a network-wide secret.");
 424                 }
 425         }
 426
 427         void OnUserConnect(User* dest)
 428         {
 429                 std::string* cloak = cu.ext.get(dest);
 430                 if (cloak)
 431                         return;
 432
 433                 if (dest->host.find('.') == std::string::npos && dest->host.find(':') == std::string::npos)
 434                         return;
 435
 436                 std::string ipstr = dest->GetIPString();
 437                 std::string chost;
 438
 439                 switch (mode)
 440                 {
 441                         case MODE_COMPAT_HOST:
 442                         {
 443                                 if (ipstr != dest->host)
 444                                 {
 445                                         std::string tail = LastTwoDomainParts(dest->host);
 446
 447                                         /** Reset the Hash module, and send it our IV and hex table */
 448                                         HashRequestIV hash(this, HashProvider, compatkey, xtab[(dest->host[0]) % 4], dest->host);
 449
 450                                         /* Generate a cloak using specialized Hash */
 451                                         chost = prefix + "-" + hash.result.substr(0,8) + tail;
 452
 453                                         /* Fix by brain - if the cloaked host is > the max length of a host (64 bytes
 454                                          * according to the DNS RFC) then they get cloaked as an IP.
 455                                          */
 456                                         if (chost.length() <= 64)
 457                                                 break;
 458                                 }
 459                                 // fall through to IP cloak
 460                         }
 461                         case MODE_COMPAT_IPONLY:
 462                                 if (dest->client_sa.sa.sa_family == AF_INET6)
 463                                         chost = CompatCloak6(ipstr.c_str());
 464                                 else
 465                                         chost = CompatCloak4(ipstr.c_str());
 466                                 break;
 467                         case MODE_HALF_CLOAK:
 468                         {
 469                                 std::string tail;
 470                                 if (ipstr != dest->host)
 471                                         tail = LastTwoDomainParts(dest->host);
 472                                 if (tail.empty() || tail.length() > 50)
 473                                         tail = ReversePartialIP(dest->client_sa);
 474                                 chost = prefix + SegmentCloak(dest->host, 1) + tail;
 475                                 break;
 476                         }
 477                         case MODE_OPAQUE:
 478                         default:
 479                                 chost = prefix + SegmentIP(dest->client_sa);
 480                 }
 481                 cu.ext.set(dest,chost);
 482         }
 483
 484 };
 485
 486 MODULE_INIT(ModuleCloaking)