src/modules/m_cloaking.cpp

   1 /*       +------------------------------------+
   2  *       | Inspire Internet Relay Chat Daemon |
   3  *       +------------------------------------+
   4  *
   5  *  InspIRCd: (C) 2002-2010 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                 IS_LOCAL(dest)->CommandFloodPenalty += 5000;
  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 && IS_LOCAL(dest))
  78                                 {
  79                                         /* Force creation of missing cloak */
  80                                         creator->OnUserConnect(IS_LOCAL(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         dynamic_reference<HashProvider> Hash;
 120
 121  public:
 122         ModuleCloaking() : cu(this), Hash(this, "hash/md5")
 123         {
 124         }
 125
 126         void init()
 127         {
 128                 OnRehash(NULL);
 129
 130                 /* Register it with the core */
 131                 if (!ServerInstance->Modes->AddMode(&cu))
 132                         throw ModuleException("Could not add new modes!");
 133
 134                 ServerInstance->Extensions.Register(&cu.ext);
 135
 136                 Implementation eventlist[] = { I_OnRehash, I_OnCheckBan, I_OnUserConnect };
 137                 ServerInstance->Modules->Attach(eventlist, this, 3);
 138         }
 139
 140         /** This function takes a domain name string and returns just the last two domain parts,
 141          * or the last domain part if only two are available. Failing that it just returns what it was given.
 142          *
 143          * For example, if it is passed "svn.inspircd.org" it will return ".inspircd.org".
 144          * If it is passed "brainbox.winbot.co.uk" it will return ".co.uk",
 145          * and if it is passed "localhost.localdomain" it will return ".localdomain".
 146          *
 147          * This is used to ensure a significant part of the host is always cloaked (see Bug #216)
 148          */
 149         std::string LastTwoDomainParts(const std::string &host)
 150         {
 151                 int dots = 0;
 152                 std::string::size_type splitdot = host.length();
 153
 154                 for (std::string::size_type x = host.length() - 1; x; --x)
 155                 {
 156                         if (host[x] == '.')
 157                         {
 158                                 splitdot = x;
 159                                 dots++;
 160                         }
 161                         if (dots >= 3)
 162                                 break;
 163                 }
 164
 165                 if (splitdot == host.length())
 166                         return host;
 167                 else
 168                         return host.substr(splitdot);
 169         }
 170
 171         std::string CompatCloak4(const char* ip)
 172         {
 173                 irc::sepstream seps(ip, '.');
 174                 std::string octet[4];
 175                 int i[4];
 176
 177                 for (int j = 0; j < 4; j++)
 178                 {
 179                         seps.GetToken(octet[j]);
 180                         i[j] = atoi(octet[j].c_str());
 181                 }
 182
 183                 octet[3] = octet[0] + "." + octet[1] + "." + octet[2] + "." + octet[3];
 184                 octet[2] = octet[0] + "." + octet[1] + "." + octet[2];
 185                 octet[1] = octet[0] + "." + octet[1];
 186
 187                 /* Reset the Hash module and send it our IV */
 188
 189                 std::string rv;
 190
 191                 /* Send the Hash module a different hex table for each octet group's Hash sum */
 192                 for (int k = 0; k < 4; k++)
 193                 {
 194                         rv.append(Hash->sumIV(compatkey, xtab[(compatkey[k]+i[k]) % 4], octet[k]).substr(0,6));
 195                         if (k < 3)
 196                                 rv.append(".");
 197                 }
 198                 /* Stick them all together */
 199                 return rv;
 200         }
 201
 202         std::string CompatCloak6(const char* ip)
 203         {
 204                 std::vector<std::string> hashies;
 205                 std::string item;
 206                 int rounds = 0;
 207
 208                 /* Reset the Hash module and send it our IV */
 209
 210                 for (const char* input = ip; *input; input++)
 211                 {
 212                         item += *input;
 213                         if (item.length() > 7)
 214                         {
 215                                 hashies.push_back(Hash->sumIV(compatkey, xtab[(compatkey[1]+rounds) % 4], item).substr(0,8));
 216                                 item.clear();
 217                         }
 218                         rounds++;
 219                 }
 220                 if (!item.empty())
 221                 {
 222                         hashies.push_back(Hash->sumIV(compatkey, xtab[(compatkey[1]+rounds) % 4], item).substr(0,8));
 223                 }
 224                 /* Stick them all together */
 225                 return irc::stringjoiner(":", hashies, 0, hashies.size() - 1).GetJoined();
 226         }
 227
 228         std::string SegmentIP(const irc::sockets::sockaddrs& ip, bool full)
 229         {
 230                 std::string bindata;
 231                 int hop1, hop2, hop3;
 232                 std::string rv;
 233                 if (ip.sa.sa_family == AF_INET6)
 234                 {
 235                         bindata = std::string((const char*)ip.in6.sin6_addr.s6_addr, 16);
 236                         hop1 = 8;
 237                         hop2 = 6;
 238                         hop3 = 4;
 239                         rv.reserve(prefix.length() + 37);
 240                 }
 241                 else
 242                 {
 243                         bindata = std::string((const char*)&ip.in4.sin_addr, 4);
 244                         hop1 = 3;
 245                         hop2 = 0;
 246                         hop3 = 2;
 247                         rv.reserve(prefix.length() + 30);
 248                 }
 249
 250                 rv.append(prefix);
 251                 rv.append(SegmentCloak(bindata, 10));
 252                 rv.append(1, '.');
 253                 bindata.erase(hop1);
 254                 rv.append(SegmentCloak(bindata, 11));
 255                 if (hop2)
 256                 {
 257                         rv.append(1, '.');
 258                         bindata.erase(hop2);
 259                         rv.append(SegmentCloak(bindata, 12));
 260                 }
 261
 262                 if (full)
 263                 {
 264                         rv.append(1, '.');
 265                         bindata.erase(hop3);
 266                         rv.append(SegmentCloak(bindata, 13));
 267                         rv.append(".IP");
 268                 }
 269                 else
 270                 {
 271                         char buf[50];
 272                         if (ip.sa.sa_family == AF_INET6)
 273                         {
 274                                 snprintf(buf, 50, ".%02x%02x.%02x%02x.IP",
 275                                         ip.in6.sin6_addr.s6_addr[2], ip.in6.sin6_addr.s6_addr[3],
 276                                         ip.in6.sin6_addr.s6_addr[0], ip.in6.sin6_addr.s6_addr[1]);
 277                         }
 278                         else
 279                         {
 280                                 const unsigned char* ip4 = (const unsigned char*)&ip.in4.sin_addr;
 281                                 snprintf(buf, 50, ".%d.%d.IP", ip4[1], ip4[0]);
 282                         }
 283                         rv.append(buf);
 284                 }
 285                 return rv;
 286         }
 287
 288         std::string SegmentCloak(const std::string& item, char id)
 289         {
 290                 std::string input;
 291                 input.reserve(key.length() + 3 + item.length());
 292                 input.append(1, id);
 293                 input.append(key);
 294                 input.append(1, 0); // null does not terminate a C++ string
 295                 input.append(item);
 296
 297                 std::string rv = Hash->sum(input).substr(0,6);
 298                 for(int i=0; i < 6; i++)
 299                 {
 300                         // this discards 3 bits per byte. We have an
 301                         // overabundance of bits in the hash output, doesn't
 302                         // matter which ones we are discarding.
 303                         rv[i] = base32[rv[i] & 0x1F];
 304                 }
 305                 return rv;
 306         }
 307
 308         ModResult OnCheckBan(User* user, Channel* chan, const std::string& mask)
 309         {
 310                 LocalUser* lu = IS_LOCAL(user);
 311                 if (!lu)
 312                         return MOD_RES_PASSTHRU;
 313
 314                 OnUserConnect(lu);
 315                 std::string* cloak = cu.ext.get(user);
 316                 /* Check if they have a cloaked host, but are not using it */
 317                 if (cloak && *cloak != user->dhost)
 318                 {
 319                         char cmask[MAXBUF];
 320                         snprintf(cmask, MAXBUF, "%s!%s@%s", user->nick.c_str(), user->ident.c_str(), cloak->c_str());
 321                         if (InspIRCd::Match(cmask,mask))
 322                                 return MOD_RES_DENY;
 323                 }
 324                 return MOD_RES_PASSTHRU;
 325         }
 326
 327         void Prioritize()
 328         {
 329                 /* Needs to be after m_banexception etc. */
 330                 ServerInstance->Modules->SetPriority(this, I_OnCheckBan, PRIORITY_LAST);
 331         }
 332
 333         ~ModuleCloaking()
 334         {
 335         }
 336
 337         Version GetVersion()
 338         {
 339                 std::string testcloak;
 340                 switch (mode)
 341                 {
 342                         case MODE_COMPAT_HOST:
 343                                 testcloak = prefix + "-" + Hash->sumIV(compatkey, xtab[0], "*").substr(0,10);
 344                                 break;
 345                         case MODE_COMPAT_IPONLY:
 346                                 testcloak = Hash->sumIV(compatkey, xtab[0], "*").substr(0,10);
 347                                 break;
 348                         case MODE_HALF_CLOAK:
 349                                 testcloak = prefix + SegmentCloak("*", 3);
 350                                 break;
 351                         case MODE_OPAQUE:
 352                         default:
 353                                 testcloak = prefix + SegmentCloak("*", 4);
 354                 }
 355                 return Version("Provides masking of user hostnames", VF_COMMON|VF_VENDOR, testcloak);
 356         }
 357
 358         void OnRehash(User* user)
 359         {
 360                 ConfigReader Conf;
 361                 prefix = Conf.ReadValue("cloak","prefix",0);
 362
 363                 std::string modestr = Conf.ReadValue("cloak", "mode", 0);
 364                 if (modestr == "compat-host")
 365                         mode = MODE_COMPAT_HOST;
 366                 else if (modestr == "compat-ip")
 367                         mode = MODE_COMPAT_IPONLY;
 368                 else if (modestr == "half")
 369                         mode = MODE_HALF_CLOAK;
 370                 else if (modestr == "full")
 371                         mode = MODE_OPAQUE;
 372                 else
 373                         throw ModuleException("Bad value for <cloak:mode>; must be one of compat-host, compat-ip, half, full");
 374
 375                 if (mode == MODE_COMPAT_HOST || mode == MODE_COMPAT_IPONLY)
 376                 {
 377                         bool lowercase = Conf.ReadFlag("cloak", "lowercase", 0);
 378
 379                         /* These are *not* using the need_positive parameter of ReadInteger -
 380                          * that will limit the valid values to only the positive values in a
 381                          * signed int. Instead, accept any value that fits into an int and
 382                          * cast it to an unsigned int. That will, a bit oddly, give us the full
 383                          * spectrum of an unsigned integer. - Special
 384                          *
 385                          * We must limit the keys or else we get different results on
 386                          * amd64/x86 boxes. - psychon */
 387                         const unsigned int limit = 0x80000000;
 388                         compatkey[0] = (unsigned int) Conf.ReadInteger("cloak","key1",0,false);
 389                         compatkey[1] = (unsigned int) Conf.ReadInteger("cloak","key2",0,false);
 390                         compatkey[2] = (unsigned int) Conf.ReadInteger("cloak","key3",0,false);
 391                         compatkey[3] = (unsigned int) Conf.ReadInteger("cloak","key4",0,false);
 392
 393                         if (!lowercase)
 394                         {
 395                                 xtab[0] = "F92E45D871BCA630";
 396                                 xtab[1] = "A1B9D80C72E653F4";
 397                                 xtab[2] = "1ABC078934DEF562";
 398                                 xtab[3] = "ABCDEF5678901234";
 399                         }
 400                         else
 401                         {
 402                                 xtab[0] = "f92e45d871bca630";
 403                                 xtab[1] = "a1b9d80c72e653f4";
 404                                 xtab[2] = "1abc078934def562";
 405                                 xtab[3] = "abcdef5678901234";
 406                         }
 407
 408                         if (prefix.empty())
 409                                 prefix = ServerInstance->Config->Network;
 410
 411                         if (!compatkey[0] || !compatkey[1] || !compatkey[2] || !compatkey[3] ||
 412                                 compatkey[0] >= limit || compatkey[1] >= limit || compatkey[2] >= limit || compatkey[3] >= limit)
 413                         {
 414                                 std::string detail;
 415                                 if (!compatkey[0] || compatkey[0] >= limit)
 416                                         detail = "<cloak:key1> is not valid, it may be set to a too high/low value, or it may not exist.";
 417                                 else if (!compatkey[1] || compatkey[1] >= limit)
 418                                         detail = "<cloak:key2> is not valid, it may be set to a too high/low value, or it may not exist.";
 419                                 else if (!compatkey[2] || compatkey[2] >= limit)
 420                                         detail = "<cloak:key3> is not valid, it may be set to a too high/low value, or it may not exist.";
 421                                 else if (!compatkey[3] || compatkey[3] >= limit)
 422                                         detail = "<cloak:key4> is not valid, it may be set to a too high/low value, or it may not exist.";
 423
 424                                 throw ModuleException("You have not defined cloak keys for m_cloaking!!! THIS IS INSECURE AND SHOULD BE CHECKED! - " + detail);
 425                         }
 426                 }
 427                 else
 428                 {
 429                         key = Conf.ReadFlag("cloak", "key", 0);
 430                         if (key.empty() || key == "secret")
 431                                 throw ModuleException("You have not defined cloak keys for m_cloaking. Define <cloak:key> as a network-wide secret.");
 432                 }
 433         }
 434
 435         void OnUserConnect(LocalUser* dest)
 436         {
 437                 std::string* cloak = cu.ext.get(dest);
 438                 if (cloak)
 439                         return;
 440
 441                 if (dest->host.find('.') == std::string::npos && dest->host.find(':') == std::string::npos)
 442                         return;
 443
 444                 std::string ipstr = dest->GetIPString();
 445                 std::string chost;
 446
 447                 switch (mode)
 448                 {
 449                         case MODE_COMPAT_HOST:
 450                         {
 451                                 if (ipstr != dest->host)
 452                                 {
 453                                         std::string tail = LastTwoDomainParts(dest->host);
 454
 455                                         /* Generate a cloak using specialized Hash */
 456                                         chost = prefix + "-" + Hash->sumIV(compatkey, xtab[(dest->host[0]) % 4], dest->host).substr(0,8) + tail;
 457
 458                                         /* Fix by brain - if the cloaked host is > the max length of a host (64 bytes
 459                                          * according to the DNS RFC) then they get cloaked as an IP.
 460                                          */
 461                                         if (chost.length() <= 64)
 462                                                 break;
 463                                 }
 464                                 // fall through to IP cloak
 465                         }
 466                         case MODE_COMPAT_IPONLY:
 467                                 if (dest->client_sa.sa.sa_family == AF_INET6)
 468                                         chost = CompatCloak6(ipstr.c_str());
 469                                 else
 470                                         chost = CompatCloak4(ipstr.c_str());
 471                                 break;
 472                         case MODE_HALF_CLOAK:
 473                         {
 474                                 if (ipstr != dest->host)
 475                                         chost = prefix + SegmentCloak(dest->host, 1) + LastTwoDomainParts(dest->host);
 476                                 if (chost.empty() || chost.length() > 50)
 477                                         chost = SegmentIP(dest->client_sa, false);
 478                                 break;
 479                         }
 480                         case MODE_OPAQUE:
 481                         default:
 482                                 chost = SegmentIP(dest->client_sa, true);
 483                 }
 484                 cu.ext.set(dest,chost);
 485         }
 486
 487 };
 488
 489 MODULE_INIT(ModuleCloaking)