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