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 "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         std::string debounce_uid;
  42         time_t debounce_ts;
  43         int debounce_count;
  44
  45         CloakUser(Module* source)
  46                 : ModeHandler(source, "cloak", 'x', PARAM_NONE, MODETYPE_USER),
  47                 ext("cloaked_host", source), debounce_ts(0), debounce_count(0)
  48         {
  49         }
  50
  51         ModeAction OnModeChange(User* source, User* dest, Channel* channel, std::string &parameter, bool adding)
  52         {
  53                 LocalUser* user = IS_LOCAL(dest);
  54
  55                 /* For remote clients, we don't take any action, we just allow it.
  56                  * The local server where they are will set their cloak instead.
  57                  * This is fine, as we will receive it later.
  58                  */
  59                 if (!user)
  60                 {
  61                         dest->SetMode('x',adding);
  62                         return MODEACTION_ALLOW;
  63                 }
  64
  65                 if (user->uuid == debounce_uid && debounce_ts == ServerInstance->Time())
  66                 {
  67                         // prevent spamming using /mode user +x-x+x-x+x-x
  68                         if (++debounce_count > 2)
  69                                 return MODEACTION_DENY;
  70                 }
  71                 else
  72                 {
  73                         debounce_uid = user->uuid;
  74                         debounce_count = 1;
  75                         debounce_ts = ServerInstance->Time();
  76                 }
  77
  78                 if (adding == user->IsModeSet('x'))
  79                         return MODEACTION_DENY;
  80
  81                 /* don't allow this user to spam modechanges */
  82                 if (source == dest)
  83                         user->CommandFloodPenalty += 5000;
  84
  85                 if (adding)
  86                 {
  87                         std::string* cloak = ext.get(user);
  88
  89                         if (!cloak)
  90                         {
  91                                 /* Force creation of missing cloak */
  92                                 creator->OnUserConnect(user);
  93                                 cloak = ext.get(user);
  94                         }
  95                         if (cloak)
  96                         {
  97                                 user->ChangeDisplayedHost(cloak->c_str());
  98                                 user->SetMode('x',true);
  99                                 return MODEACTION_ALLOW;
 100                         }
 101                         else
 102                                 return MODEACTION_DENY;
 103                 }
 104                 else
 105                 {
 106                         /* User is removing the mode, so restore their real host
 107                          * and make it match the displayed one.
 108                          */
 109                         user->ChangeDisplayedHost(user->host.c_str());
 110                         user->SetMode('x',false);
 111                         return MODEACTION_ALLOW;
 112                 }
 113         }
 114
 115 };
 116
 117
 118 class ModuleCloaking : public Module
 119 {
 120  private:
 121         CloakUser cu;
 122         CloakMode mode;
 123         std::string prefix;
 124         std::string key;
 125         unsigned int compatkey[4];
 126         const char* xtab[4];
 127         dynamic_reference<HashProvider> Hash;
 128
 129  public:
 130         ModuleCloaking() : cu(this), mode(MODE_OPAQUE), Hash(this, "hash/md5")
 131         {
 132         }
 133
 134         void init()
 135         {
 136                 OnRehash(NULL);
 137
 138                 /* Register it with the core */
 139                 if (!ServerInstance->Modes->AddMode(&cu))
 140                         throw ModuleException("Could not add new modes!");
 141
 142                 ServerInstance->Extensions.Register(&cu.ext);
 143
 144                 Implementation eventlist[] = { I_OnRehash, I_OnCheckBan, I_OnUserConnect, I_OnChangeHost };
 145                 ServerInstance->Modules->Attach(eventlist, this, 4);
 146         }
 147
 148         /** This function takes a domain name string and returns just the last two domain parts,
 149          * or the last domain part if only two are available. Failing that it just returns what it was given.
 150          *
 151          * For example, if it is passed "svn.inspircd.org" it will return ".inspircd.org".
 152          * If it is passed "brainbox.winbot.co.uk" it will return ".co.uk",
 153          * and if it is passed "localhost.localdomain" it will return ".localdomain".
 154          *
 155          * This is used to ensure a significant part of the host is always cloaked (see Bug #216)
 156          */
 157         std::string LastTwoDomainParts(const std::string &host)
 158         {
 159                 int dots = 0;
 160                 std::string::size_type splitdot = host.length();
 161
 162                 for (std::string::size_type x = host.length() - 1; x; --x)
 163                 {
 164                         if (host[x] == '.')
 165                         {
 166                                 splitdot = x;
 167                                 dots++;
 168                         }
 169                         if (dots >= 3)
 170                                 break;
 171                 }
 172
 173                 if (splitdot == host.length())
 174                         return "";
 175                 else
 176                         return host.substr(splitdot);
 177         }
 178
 179         /**
 180          * 2.0-style cloaking function
 181          * @param item The item to cloak (part of an IP or hostname)
 182          * @param id A unique ID for this type of item (to make it unique if the item matches)
 183          * @param len The length of the output. Maximum for MD5 is 16 characters.
 184          */
 185         std::string SegmentCloak(const std::string& item, char id, int len)
 186         {
 187                 std::string input;
 188                 input.reserve(key.length() + 3 + item.length());
 189                 input.append(1, id);
 190                 input.append(key);
 191                 input.append(1, 0); // null does not terminate a C++ string
 192                 input.append(item);
 193
 194                 std::string rv = Hash->sum(input).substr(0,len);
 195                 for(int i=0; i < len; i++)
 196                 {
 197                         // this discards 3 bits per byte. We have an
 198                         // overabundance of bits in the hash output, doesn't
 199                         // matter which ones we are discarding.
 200                         rv[i] = base32[rv[i] & 0x1F];
 201                 }
 202                 return rv;
 203         }
 204
 205         std::string CompatCloak4(const char* ip)
 206         {
 207                 irc::sepstream seps(ip, '.');
 208                 std::string octet[4];
 209                 int i[4];
 210
 211                 for (int j = 0; j < 4; j++)
 212                 {
 213                         seps.GetToken(octet[j]);
 214                         i[j] = atoi(octet[j].c_str());
 215                 }
 216
 217                 octet[3] = octet[0] + "." + octet[1] + "." + octet[2] + "." + octet[3];
 218                 octet[2] = octet[0] + "." + octet[1] + "." + octet[2];
 219                 octet[1] = octet[0] + "." + octet[1];
 220
 221                 /* Reset the Hash module and send it our IV */
 222
 223                 std::string rv;
 224
 225                 /* Send the Hash module a different hex table for each octet group's Hash sum */
 226                 for (int k = 0; k < 4; k++)
 227                 {
 228                         rv.append(Hash->sumIV(compatkey, xtab[(compatkey[k]+i[k]) % 4], octet[k]).substr(0,6));
 229                         if (k < 3)
 230                                 rv.append(".");
 231                 }
 232                 /* Stick them all together */
 233                 return rv;
 234         }
 235
 236         std::string CompatCloak6(const char* ip)
 237         {
 238                 std::vector<std::string> hashies;
 239                 std::string item;
 240                 int rounds = 0;
 241
 242                 /* Reset the Hash module and send it our IV */
 243
 244                 for (const char* input = ip; *input; input++)
 245                 {
 246                         item += *input;
 247                         if (item.length() > 7)
 248                         {
 249                                 hashies.push_back(Hash->sumIV(compatkey, xtab[(compatkey[1]+rounds) % 4], item).substr(0,8));
 250                                 item.clear();
 251                         }
 252                         rounds++;
 253                 }
 254                 if (!item.empty())
 255                 {
 256                         hashies.push_back(Hash->sumIV(compatkey, xtab[(compatkey[1]+rounds) % 4], item).substr(0,8));
 257                 }
 258                 /* Stick them all together */
 259                 return irc::stringjoiner(":", hashies, 0, hashies.size() - 1).GetJoined();
 260         }
 261
 262         std::string SegmentIP(const irc::sockets::sockaddrs& ip, bool full)
 263         {
 264                 std::string bindata;
 265                 int hop1, hop2, hop3;
 266                 int len1, len2;
 267                 std::string rv;
 268                 if (ip.sa.sa_family == AF_INET6)
 269                 {
 270                         bindata = std::string((const char*)ip.in6.sin6_addr.s6_addr, 16);
 271                         hop1 = 8;
 272                         hop2 = 6;
 273                         hop3 = 4;
 274                         len1 = 6;
 275                         len2 = 4;
 276                         rv.reserve(prefix.length() + 29);
 277                 }
 278                 else
 279                 {
 280                         bindata = std::string((const char*)&ip.in4.sin_addr, 4);
 281                         hop1 = 3;
 282                         hop2 = 0;
 283                         hop3 = 2;
 284                         len1 = len2 = 3;
 285                         rv.reserve(prefix.length() + 18);
 286                 }
 287
 288                 rv.append(prefix);
 289                 rv.append(SegmentCloak(bindata, 10, len1));
 290                 rv.append(1, '.');
 291                 bindata.erase(hop1);
 292                 rv.append(SegmentCloak(bindata, 11, len2));
 293                 if (hop2)
 294                 {
 295                         rv.append(1, '.');
 296                         bindata.erase(hop2);
 297                         rv.append(SegmentCloak(bindata, 12, len2));
 298                 }
 299
 300                 if (full)
 301                 {
 302                         rv.append(1, '.');
 303                         bindata.erase(hop3);
 304                         rv.append(SegmentCloak(bindata, 13, 6));
 305                         rv.append(".IP");
 306                 }
 307                 else
 308                 {
 309                         char buf[50];
 310                         if (ip.sa.sa_family == AF_INET6)
 311                         {
 312                                 snprintf(buf, 50, ".%02x%02x.%02x%02x.IP",
 313                                         ip.in6.sin6_addr.s6_addr[2], ip.in6.sin6_addr.s6_addr[3],
 314                                         ip.in6.sin6_addr.s6_addr[0], ip.in6.sin6_addr.s6_addr[1]);
 315                         }
 316                         else
 317                         {
 318                                 const unsigned char* ip4 = (const unsigned char*)&ip.in4.sin_addr;
 319                                 snprintf(buf, 50, ".%d.%d.IP", ip4[1], ip4[0]);
 320                         }
 321                         rv.append(buf);
 322                 }
 323                 return rv;
 324         }
 325
 326         ModResult OnCheckBan(User* user, Channel* chan, const std::string& mask)
 327         {
 328                 LocalUser* lu = IS_LOCAL(user);
 329                 if (!lu)
 330                         return MOD_RES_PASSTHRU;
 331
 332                 OnUserConnect(lu);
 333                 std::string* cloak = cu.ext.get(user);
 334                 /* Check if they have a cloaked host, but are not using it */
 335                 if (cloak && *cloak != user->dhost)
 336                 {
 337                         char cmask[MAXBUF];
 338                         snprintf(cmask, MAXBUF, "%s!%s@%s", user->nick.c_str(), user->ident.c_str(), cloak->c_str());
 339                         if (InspIRCd::Match(cmask,mask))
 340                                 return MOD_RES_DENY;
 341                 }
 342                 return MOD_RES_PASSTHRU;
 343         }
 344
 345         void Prioritize()
 346         {
 347                 /* Needs to be after m_banexception etc. */
 348                 ServerInstance->Modules->SetPriority(this, I_OnCheckBan, PRIORITY_LAST);
 349         }
 350
 351         // this unsets umode +x on every host change. If we are actually doing a +x
 352         // mode change, we will call SetMode back to true AFTER the host change is done.
 353         void OnChangeHost(User* u, const std::string& host)
 354         {
 355                 u->SetMode('x', false);
 356         }
 357
 358         ~ModuleCloaking()
 359         {
 360         }
 361
 362         Version GetVersion()
 363         {
 364                 std::string testcloak = "broken";
 365                 if (Hash)
 366                 {
 367                         switch (mode)
 368                         {
 369                                 case MODE_COMPAT_HOST:
 370                                         testcloak = prefix + "-" + Hash->sumIV(compatkey, xtab[0], "*").substr(0,10);
 371                                         break;
 372                                 case MODE_COMPAT_IPONLY:
 373                                         testcloak = Hash->sumIV(compatkey, xtab[0], "*").substr(0,10);
 374                                         break;
 375                                 case MODE_HALF_CLOAK:
 376                                         testcloak = prefix + SegmentCloak("*", 3, 8);
 377                                         break;
 378                                 case MODE_OPAQUE:
 379                                         testcloak = prefix + SegmentCloak("*", 4, 8);
 380                         }
 381                 }
 382                 return Version("Provides masking of user hostnames", VF_COMMON|VF_VENDOR, testcloak);
 383         }
 384
 385         void OnRehash(User* user)
 386         {
 387                 ConfigReader Conf;
 388                 prefix = Conf.ReadValue("cloak","prefix",0);
 389
 390                 std::string modestr = Conf.ReadValue("cloak", "mode", 0);
 391                 if (modestr == "compat-host")
 392                         mode = MODE_COMPAT_HOST;
 393                 else if (modestr == "compat-ip")
 394                         mode = MODE_COMPAT_IPONLY;
 395                 else if (modestr == "half")
 396                         mode = MODE_HALF_CLOAK;
 397                 else if (modestr == "full")
 398                         mode = MODE_OPAQUE;
 399                 else
 400                         throw ModuleException("Bad value for <cloak:mode>; must be one of compat-host, compat-ip, half, full");
 401
 402                 if (mode == MODE_COMPAT_HOST || mode == MODE_COMPAT_IPONLY)
 403                 {
 404                         bool lowercase = Conf.ReadFlag("cloak", "lowercase", 0);
 405
 406                         /* These are *not* using the need_positive parameter of ReadInteger -
 407                          * that will limit the valid values to only the positive values in a
 408                          * signed int. Instead, accept any value that fits into an int and
 409                          * cast it to an unsigned int. That will, a bit oddly, give us the full
 410                          * spectrum of an unsigned integer. - Special
 411                          *
 412                          * We must limit the keys or else we get different results on
 413                          * amd64/x86 boxes. - psychon */
 414                         const unsigned int limit = 0x80000000;
 415                         compatkey[0] = (unsigned int) Conf.ReadInteger("cloak","key1",0,false);
 416                         compatkey[1] = (unsigned int) Conf.ReadInteger("cloak","key2",0,false);
 417                         compatkey[2] = (unsigned int) Conf.ReadInteger("cloak","key3",0,false);
 418                         compatkey[3] = (unsigned int) Conf.ReadInteger("cloak","key4",0,false);
 419
 420                         if (!lowercase)
 421                         {
 422                                 xtab[0] = "F92E45D871BCA630";
 423                                 xtab[1] = "A1B9D80C72E653F4";
 424                                 xtab[2] = "1ABC078934DEF562";
 425                                 xtab[3] = "ABCDEF5678901234";
 426                         }
 427                         else
 428                         {
 429                                 xtab[0] = "f92e45d871bca630";
 430                                 xtab[1] = "a1b9d80c72e653f4";
 431                                 xtab[2] = "1abc078934def562";
 432                                 xtab[3] = "abcdef5678901234";
 433                         }
 434
 435                         if (prefix.empty())
 436                                 prefix = ServerInstance->Config->Network;
 437
 438                         if (!compatkey[0] || !compatkey[1] || !compatkey[2] || !compatkey[3] ||
 439                                 compatkey[0] >= limit || compatkey[1] >= limit || compatkey[2] >= limit || compatkey[3] >= limit)
 440                         {
 441                                 std::string detail;
 442                                 if (!compatkey[0] || compatkey[0] >= limit)
 443                                         detail = "<cloak:key1> is not valid, it may be set to a too high/low value, or it may not exist.";
 444                                 else if (!compatkey[1] || compatkey[1] >= limit)
 445                                         detail = "<cloak:key2> is not valid, it may be set to a too high/low value, or it may not exist.";
 446                                 else if (!compatkey[2] || compatkey[2] >= limit)
 447                                         detail = "<cloak:key3> is not valid, it may be set to a too high/low value, or it may not exist.";
 448                                 else if (!compatkey[3] || compatkey[3] >= limit)
 449                                         detail = "<cloak:key4> is not valid, it may be set to a too high/low value, or it may not exist.";
 450
 451                                 throw ModuleException("You have not defined cloak keys for m_cloaking!!! THIS IS INSECURE AND SHOULD BE CHECKED! - " + detail);
 452                         }
 453                 }
 454                 else
 455                 {
 456                         key = Conf.ReadFlag("cloak", "key", 0);
 457                         if (key.empty() || key == "secret")
 458                                 throw ModuleException("You have not defined cloak keys for m_cloaking. Define <cloak:key> as a network-wide secret.");
 459                 }
 460         }
 461
 462         void OnUserConnect(LocalUser* dest)
 463         {
 464                 std::string* cloak = cu.ext.get(dest);
 465                 if (cloak)
 466                         return;
 467
 468                 std::string ipstr = dest->GetIPString();
 469                 std::string chost;
 470
 471                 switch (mode)
 472                 {
 473                         case MODE_COMPAT_HOST:
 474                         {
 475                                 if (ipstr != dest->host)
 476                                 {
 477                                         std::string tail = LastTwoDomainParts(dest->host);
 478
 479                                         /* Generate a cloak using specialized Hash */
 480                                         chost = prefix + "-" + Hash->sumIV(compatkey, xtab[(dest->host[0]) % 4], dest->host).substr(0,8) + tail;
 481
 482                                         /* Fix by brain - if the cloaked host is > the max length of a host (64 bytes
 483                                          * according to the DNS RFC) then they get cloaked as an IP.
 484                                          */
 485                                         if (chost.length() <= 64)
 486                                                 break;
 487                                 }
 488                                 // fall through to IP cloak
 489                         }
 490                         case MODE_COMPAT_IPONLY:
 491                                 if (dest->client_sa.sa.sa_family == AF_INET6)
 492                                         chost = CompatCloak6(ipstr.c_str());
 493                                 else
 494                                         chost = CompatCloak4(ipstr.c_str());
 495                                 break;
 496                         case MODE_HALF_CLOAK:
 497                         {
 498                                 if (ipstr != dest->host)
 499                                         chost = prefix + SegmentCloak(dest->host, 1, 6) + LastTwoDomainParts(dest->host);
 500                                 if (chost.empty() || chost.length() > 50)
 501                                         chost = SegmentIP(dest->client_sa, false);
 502                                 break;
 503                         }
 504                         case MODE_OPAQUE:
 505                         default:
 506                                 chost = SegmentIP(dest->client_sa, true);
 507                 }
 508                 cu.ext.set(dest,chost);
 509         }
 510
 511 };
 512
 513 MODULE_INIT(ModuleCloaking)