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         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 && !dest->IsModeSet('x'))
  63                 {
  64                         std::string* cloak = ext.get(dest);
  65
  66                         if (!cloak)
  67                         {
  68                                 /* Force creation of missing cloak */
  69                                 creator->OnUserConnect(IS_LOCAL(dest));
  70                                 cloak = ext.get(dest);
  71                         }
  72                         if (cloak)
  73                         {
  74                                 dest->ChangeDisplayedHost(cloak->c_str());
  75                                 dest->SetMode('x',true);
  76                                 return MODEACTION_ALLOW;
  77                         }
  78                 }
  79                 else if (!adding && dest->IsModeSet('x'))
  80                 {
  81                         /* User is removing the mode, so restore their real host
  82                          * and make it match the displayed one.
  83                          */
  84                         dest->ChangeDisplayedHost(dest->host.c_str());
  85                         dest->SetMode('x',false);
  86                         return MODEACTION_ALLOW;
  87                 }
  88
  89                 return MODEACTION_DENY;
  90         }
  91
  92 };
  93
  94
  95 class ModuleCloaking : public Module
  96 {
  97  private:
  98         CloakUser cu;
  99         CloakMode mode;
 100         std::string prefix;
 101         std::string key;
 102         unsigned int compatkey[4];
 103         const char* xtab[4];
 104         dynamic_reference<HashProvider> Hash;
 105
 106  public:
 107         ModuleCloaking() : cu(this), Hash(this, "hash/md5")
 108         {
 109         }
 110
 111         void init()
 112         {
 113                 OnRehash(NULL);
 114
 115                 /* Register it with the core */
 116                 if (!ServerInstance->Modes->AddMode(&cu))
 117                         throw ModuleException("Could not add new modes!");
 118
 119                 ServerInstance->Extensions.Register(&cu.ext);
 120
 121                 Implementation eventlist[] = { I_OnRehash, I_OnCheckBan, I_OnUserConnect, I_OnChangeHost };
 122                 ServerInstance->Modules->Attach(eventlist, this, 4);
 123         }
 124
 125         /** This function takes a domain name string and returns just the last two domain parts,
 126          * or the last domain part if only two are available. Failing that it just returns what it was given.
 127          *
 128          * For example, if it is passed "svn.inspircd.org" it will return ".inspircd.org".
 129          * If it is passed "brainbox.winbot.co.uk" it will return ".co.uk",
 130          * and if it is passed "localhost.localdomain" it will return ".localdomain".
 131          *
 132          * This is used to ensure a significant part of the host is always cloaked (see Bug #216)
 133          */
 134         std::string LastTwoDomainParts(const std::string &host)
 135         {
 136                 int dots = 0;
 137                 std::string::size_type splitdot = host.length();
 138
 139                 for (std::string::size_type x = host.length() - 1; x; --x)
 140                 {
 141                         if (host[x] == '.')
 142                         {
 143                                 splitdot = x;
 144                                 dots++;
 145                         }
 146                         if (dots >= 3)
 147                                 break;
 148                 }
 149
 150                 if (splitdot == host.length())
 151                         return host;
 152                 else
 153                         return host.substr(splitdot);
 154         }
 155
 156         std::string CompatCloak4(const char* ip)
 157         {
 158                 irc::sepstream seps(ip, '.');
 159                 std::string octet[4];
 160                 int i[4];
 161
 162                 for (int j = 0; j < 4; j++)
 163                 {
 164                         seps.GetToken(octet[j]);
 165                         i[j] = atoi(octet[j].c_str());
 166                 }
 167
 168                 octet[3] = octet[0] + "." + octet[1] + "." + octet[2] + "." + octet[3];
 169                 octet[2] = octet[0] + "." + octet[1] + "." + octet[2];
 170                 octet[1] = octet[0] + "." + octet[1];
 171
 172                 /* Reset the Hash module and send it our IV */
 173
 174                 std::string rv;
 175
 176                 /* Send the Hash module a different hex table for each octet group's Hash sum */
 177                 for (int k = 0; k < 4; k++)
 178                 {
 179                         rv.append(Hash->sumIV(compatkey, xtab[(compatkey[k]+i[k]) % 4], octet[k]).substr(0,6));
 180                         if (k < 3)
 181                                 rv.append(".");
 182                 }
 183                 /* Stick them all together */
 184                 return rv;
 185         }
 186
 187         std::string CompatCloak6(const char* ip)
 188         {
 189                 std::vector<std::string> hashies;
 190                 std::string item;
 191                 int rounds = 0;
 192
 193                 /* Reset the Hash module and send it our IV */
 194
 195                 for (const char* input = ip; *input; input++)
 196                 {
 197                         item += *input;
 198                         if (item.length() > 7)
 199                         {
 200                                 hashies.push_back(Hash->sumIV(compatkey, xtab[(compatkey[1]+rounds) % 4], item).substr(0,8));
 201                                 item.clear();
 202                         }
 203                         rounds++;
 204                 }
 205                 if (!item.empty())
 206                 {
 207                         hashies.push_back(Hash->sumIV(compatkey, xtab[(compatkey[1]+rounds) % 4], item).substr(0,8));
 208                 }
 209                 /* Stick them all together */
 210                 return irc::stringjoiner(":", hashies, 0, hashies.size() - 1).GetJoined();
 211         }
 212
 213         std::string SegmentIP(const irc::sockets::sockaddrs& ip, bool full)
 214         {
 215                 std::string bindata;
 216                 int hop1, hop2, hop3;
 217                 std::string rv;
 218                 if (ip.sa.sa_family == AF_INET6)
 219                 {
 220                         bindata = std::string((const char*)ip.in6.sin6_addr.s6_addr, 16);
 221                         hop1 = 8;
 222                         hop2 = 6;
 223                         hop3 = 4;
 224                         rv.reserve(prefix.length() + 37);
 225                 }
 226                 else
 227                 {
 228                         bindata = std::string((const char*)&ip.in4.sin_addr, 4);
 229                         hop1 = 3;
 230                         hop2 = 0;
 231                         hop3 = 2;
 232                         rv.reserve(prefix.length() + 30);
 233                 }
 234
 235                 rv.append(prefix);
 236                 rv.append(SegmentCloak(bindata, 10));
 237                 rv.append(1, '.');
 238                 bindata.erase(hop1);
 239                 rv.append(SegmentCloak(bindata, 11));
 240                 if (hop2)
 241                 {
 242                         rv.append(1, '.');
 243                         bindata.erase(hop2);
 244                         rv.append(SegmentCloak(bindata, 12));
 245                 }
 246
 247                 if (full)
 248                 {
 249                         rv.append(1, '.');
 250                         bindata.erase(hop3);
 251                         rv.append(SegmentCloak(bindata, 13));
 252                         rv.append(".IP");
 253                 }
 254                 else
 255                 {
 256                         char buf[50];
 257                         if (ip.sa.sa_family == AF_INET6)
 258                         {
 259                                 snprintf(buf, 50, ".%02x%02x.%02x%02x.IP",
 260                                         ip.in6.sin6_addr.s6_addr[2], ip.in6.sin6_addr.s6_addr[3],
 261                                         ip.in6.sin6_addr.s6_addr[0], ip.in6.sin6_addr.s6_addr[1]);
 262                         }
 263                         else
 264                         {
 265                                 const unsigned char* ip4 = (const unsigned char*)&ip.in4.sin_addr;
 266                                 snprintf(buf, 50, ".%d.%d.IP", ip4[1], ip4[0]);
 267                         }
 268                         rv.append(buf);
 269                 }
 270                 return rv;
 271         }
 272
 273         std::string SegmentCloak(const std::string& item, char id)
 274         {
 275                 std::string input;
 276                 input.reserve(key.length() + 3 + item.length());
 277                 input.append(1, id);
 278                 input.append(key);
 279                 input.append(1, 0); // null does not terminate a C++ string
 280                 input.append(item);
 281
 282                 std::string rv = Hash->sum(input).substr(0,6);
 283                 for(int i=0; i < 6; i++)
 284                 {
 285                         // this discards 3 bits per byte. We have an
 286                         // overabundance of bits in the hash output, doesn't
 287                         // matter which ones we are discarding.
 288                         rv[i] = base32[rv[i] & 0x1F];
 289                 }
 290                 return rv;
 291         }
 292
 293         ModResult OnCheckBan(User* user, Channel* chan, const std::string& mask)
 294         {
 295                 LocalUser* lu = IS_LOCAL(user);
 296                 if (!lu)
 297                         return MOD_RES_PASSTHRU;
 298
 299                 OnUserConnect(lu);
 300                 std::string* cloak = cu.ext.get(user);
 301                 /* Check if they have a cloaked host, but are not using it */
 302                 if (cloak && *cloak != user->dhost)
 303                 {
 304                         char cmask[MAXBUF];
 305                         snprintf(cmask, MAXBUF, "%s!%s@%s", user->nick.c_str(), user->ident.c_str(), cloak->c_str());
 306                         if (InspIRCd::Match(cmask,mask))
 307                                 return MOD_RES_DENY;
 308                 }
 309                 return MOD_RES_PASSTHRU;
 310         }
 311
 312         void Prioritize()
 313         {
 314                 /* Needs to be after m_banexception etc. */
 315                 ServerInstance->Modules->SetPriority(this, I_OnCheckBan, PRIORITY_LAST);
 316         }
 317
 318         // this unsets umode +x on every host change. If we are actually doing a +x
 319         // mode change, we will call SetMode back to true AFTER the host change is done.
 320         void OnChangeHost(User* u, const std::string& host)
 321         {
 322                 u->SetMode('x', false);
 323         }
 324
 325         ~ModuleCloaking()
 326         {
 327         }
 328
 329         Version GetVersion()
 330         {
 331                 std::string testcloak = "broken";
 332                 if (Hash)
 333                 {
 334                         switch (mode)
 335                         {
 336                                 case MODE_COMPAT_HOST:
 337                                         testcloak = prefix + "-" + Hash->sumIV(compatkey, xtab[0], "*").substr(0,10);
 338                                         break;
 339                                 case MODE_COMPAT_IPONLY:
 340                                         testcloak = Hash->sumIV(compatkey, xtab[0], "*").substr(0,10);
 341                                         break;
 342                                 case MODE_HALF_CLOAK:
 343                                         testcloak = prefix + SegmentCloak("*", 3);
 344                                         break;
 345                                 case MODE_OPAQUE:
 346                                         testcloak = prefix + SegmentCloak("*", 4);
 347                         }
 348                 }
 349                 return Version("Provides masking of user hostnames", VF_COMMON|VF_VENDOR, testcloak);
 350         }
 351
 352         void OnRehash(User* user)
 353         {
 354                 ConfigReader Conf;
 355                 prefix = Conf.ReadValue("cloak","prefix",0);
 356
 357                 std::string modestr = Conf.ReadValue("cloak", "mode", 0);
 358                 if (modestr == "compat-host")
 359                         mode = MODE_COMPAT_HOST;
 360                 else if (modestr == "compat-ip")
 361                         mode = MODE_COMPAT_IPONLY;
 362                 else if (modestr == "half")
 363                         mode = MODE_HALF_CLOAK;
 364                 else if (modestr == "full")
 365                         mode = MODE_OPAQUE;
 366                 else
 367                         throw ModuleException("Bad value for <cloak:mode>; must be one of compat-host, compat-ip, half, full");
 368
 369                 if (mode == MODE_COMPAT_HOST || mode == MODE_COMPAT_IPONLY)
 370                 {
 371                         bool lowercase = Conf.ReadFlag("cloak", "lowercase", 0);
 372
 373                         /* These are *not* using the need_positive parameter of ReadInteger -
 374                          * that will limit the valid values to only the positive values in a
 375                          * signed int. Instead, accept any value that fits into an int and
 376                          * cast it to an unsigned int. That will, a bit oddly, give us the full
 377                          * spectrum of an unsigned integer. - Special
 378                          *
 379                          * We must limit the keys or else we get different results on
 380                          * amd64/x86 boxes. - psychon */
 381                         const unsigned int limit = 0x80000000;
 382                         compatkey[0] = (unsigned int) Conf.ReadInteger("cloak","key1",0,false);
 383                         compatkey[1] = (unsigned int) Conf.ReadInteger("cloak","key2",0,false);
 384                         compatkey[2] = (unsigned int) Conf.ReadInteger("cloak","key3",0,false);
 385                         compatkey[3] = (unsigned int) Conf.ReadInteger("cloak","key4",0,false);
 386
 387                         if (!lowercase)
 388                         {
 389                                 xtab[0] = "F92E45D871BCA630";
 390                                 xtab[1] = "A1B9D80C72E653F4";
 391                                 xtab[2] = "1ABC078934DEF562";
 392                                 xtab[3] = "ABCDEF5678901234";
 393                         }
 394                         else
 395                         {
 396                                 xtab[0] = "f92e45d871bca630";
 397                                 xtab[1] = "a1b9d80c72e653f4";
 398                                 xtab[2] = "1abc078934def562";
 399                                 xtab[3] = "abcdef5678901234";
 400                         }
 401
 402                         if (prefix.empty())
 403                                 prefix = ServerInstance->Config->Network;
 404
 405                         if (!compatkey[0] || !compatkey[1] || !compatkey[2] || !compatkey[3] ||
 406                                 compatkey[0] >= limit || compatkey[1] >= limit || compatkey[2] >= limit || compatkey[3] >= limit)
 407                         {
 408                                 std::string detail;
 409                                 if (!compatkey[0] || compatkey[0] >= limit)
 410                                         detail = "<cloak:key1> is not valid, it may be set to a too high/low value, or it may not exist.";
 411                                 else if (!compatkey[1] || compatkey[1] >= limit)
 412                                         detail = "<cloak:key2> is not valid, it may be set to a too high/low value, or it may not exist.";
 413                                 else if (!compatkey[2] || compatkey[2] >= limit)
 414                                         detail = "<cloak:key3> is not valid, it may be set to a too high/low value, or it may not exist.";
 415                                 else if (!compatkey[3] || compatkey[3] >= limit)
 416                                         detail = "<cloak:key4> is not valid, it may be set to a too high/low value, or it may not exist.";
 417
 418                                 throw ModuleException("You have not defined cloak keys for m_cloaking!!! THIS IS INSECURE AND SHOULD BE CHECKED! - " + detail);
 419                         }
 420                 }
 421                 else
 422                 {
 423                         key = Conf.ReadFlag("cloak", "key", 0);
 424                         if (key.empty() || key == "secret")
 425                                 throw ModuleException("You have not defined cloak keys for m_cloaking. Define <cloak:key> as a network-wide secret.");
 426                 }
 427         }
 428
 429         void OnUserConnect(LocalUser* dest)
 430         {
 431                 std::string* cloak = cu.ext.get(dest);
 432                 if (cloak)
 433                         return;
 434
 435                 std::string ipstr = dest->GetIPString();
 436                 std::string chost;
 437
 438                 switch (mode)
 439                 {
 440                         case MODE_COMPAT_HOST:
 441                         {
 442                                 if (ipstr != dest->host)
 443                                 {
 444                                         std::string tail = LastTwoDomainParts(dest->host);
 445
 446                                         /* Generate a cloak using specialized Hash */
 447                                         chost = prefix + "-" + Hash->sumIV(compatkey, xtab[(dest->host[0]) % 4], dest->host).substr(0,8) + tail;
 448
 449                                         /* Fix by brain - if the cloaked host is > the max length of a host (64 bytes
 450                                          * according to the DNS RFC) then they get cloaked as an IP.
 451                                          */
 452                                         if (chost.length() <= 64)
 453                                                 break;
 454                                 }
 455                                 // fall through to IP cloak
 456                         }
 457                         case MODE_COMPAT_IPONLY:
 458                                 if (dest->client_sa.sa.sa_family == AF_INET6)
 459                                         chost = CompatCloak6(ipstr.c_str());
 460                                 else
 461                                         chost = CompatCloak4(ipstr.c_str());
 462                                 break;
 463                         case MODE_HALF_CLOAK:
 464                         {
 465                                 if (ipstr != dest->host)
 466                                         chost = prefix + SegmentCloak(dest->host, 1) + LastTwoDomainParts(dest->host);
 467                                 if (chost.empty() || chost.length() > 50)
 468                                         chost = SegmentIP(dest->client_sa, false);
 469                                 break;
 470                         }
 471                         case MODE_OPAQUE:
 472                         default:
 473                                 chost = SegmentIP(dest->client_sa, true);
 474                 }
 475                 cu.ext.set(dest,chost);
 476         }
 477
 478 };
 479
 480 MODULE_INIT(ModuleCloaking)