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 suffix;
 125         std::string key;
 126         unsigned int compatkey[4];
 127         const char* xtab[4];
 128         dynamic_reference<HashProvider> Hash;
 129
 130  public:
 131         ModuleCloaking() : cu(this), mode(MODE_OPAQUE), Hash(this, "hash/md5")
 132         {
 133         }
 134
 135         void init()
 136         {
 137                 OnRehash(NULL);
 138
 139                 /* Register it with the core */
 140                 if (!ServerInstance->Modes->AddMode(&cu))
 141                         throw ModuleException("Could not add new modes!");
 142
 143                 ServerInstance->Extensions.Register(&cu.ext);
 144
 145                 Implementation eventlist[] = { I_OnRehash, I_OnCheckBan, I_OnUserConnect, I_OnChangeHost };
 146                 ServerInstance->Modules->Attach(eventlist, this, 4);
 147         }
 148
 149         /** This function takes a domain name string and returns just the last two domain parts,
 150          * or the last domain part if only two are available. Failing that it just returns what it was given.
 151          *
 152          * For example, if it is passed "svn.inspircd.org" it will return ".inspircd.org".
 153          * If it is passed "brainbox.winbot.co.uk" it will return ".co.uk",
 154          * and if it is passed "localhost.localdomain" it will return ".localdomain".
 155          *
 156          * This is used to ensure a significant part of the host is always cloaked (see Bug #216)
 157          */
 158         std::string LastTwoDomainParts(const std::string &host)
 159         {
 160                 int dots = 0;
 161                 std::string::size_type splitdot = host.length();
 162
 163                 for (std::string::size_type x = host.length() - 1; x; --x)
 164                 {
 165                         if (host[x] == '.')
 166                         {
 167                                 splitdot = x;
 168                                 dots++;
 169                         }
 170                         if (dots >= 3)
 171                                 break;
 172                 }
 173
 174                 if (splitdot == host.length())
 175                         return "";
 176                 else
 177                         return host.substr(splitdot);
 178         }
 179
 180         /**
 181          * 2.0-style cloaking function
 182          * @param item The item to cloak (part of an IP or hostname)
 183          * @param id A unique ID for this type of item (to make it unique if the item matches)
 184          * @param len The length of the output. Maximum for MD5 is 16 characters.
 185          */
 186         std::string SegmentCloak(const std::string& item, char id, int len)
 187         {
 188                 std::string input;
 189                 input.reserve(key.length() + 3 + item.length());
 190                 input.append(1, id);
 191                 input.append(key);
 192                 input.append(1, 0); // null does not terminate a C++ string
 193                 input.append(item);
 194
 195                 std::string rv = Hash->sum(input).substr(0,len);
 196                 for(int i=0; i < len; i++)
 197                 {
 198                         // this discards 3 bits per byte. We have an
 199                         // overabundance of bits in the hash output, doesn't
 200                         // matter which ones we are discarding.
 201                         rv[i] = base32[rv[i] & 0x1F];
 202                 }
 203                 return rv;
 204         }
 205
 206         std::string CompatCloak4(const char* ip)
 207         {
 208                 irc::sepstream seps(ip, '.');
 209                 std::string octet[4];
 210                 int i[4];
 211
 212                 for (int j = 0; j < 4; j++)
 213                 {
 214                         seps.GetToken(octet[j]);
 215                         i[j] = atoi(octet[j].c_str());
 216                 }
 217
 218                 octet[3] = octet[0] + "." + octet[1] + "." + octet[2] + "." + octet[3];
 219                 octet[2] = octet[0] + "." + octet[1] + "." + octet[2];
 220                 octet[1] = octet[0] + "." + octet[1];
 221
 222                 /* Reset the Hash module and send it our IV */
 223
 224                 std::string rv;
 225
 226                 /* Send the Hash module a different hex table for each octet group's Hash sum */
 227                 for (int k = 0; k < 4; k++)
 228                 {
 229                         rv.append(Hash->sumIV(compatkey, xtab[(compatkey[k]+i[k]) % 4], octet[k]).substr(0,6));
 230                         if (k < 3)
 231                                 rv.append(".");
 232                 }
 233                 /* Stick them all together */
 234                 return rv;
 235         }
 236
 237         std::string CompatCloak6(const char* ip)
 238         {
 239                 std::vector<std::string> hashies;
 240                 std::string item;
 241                 int rounds = 0;
 242
 243                 /* Reset the Hash module and send it our IV */
 244
 245                 for (const char* input = ip; *input; input++)
 246                 {
 247                         item += *input;
 248                         if (item.length() > 7)
 249                         {
 250                                 hashies.push_back(Hash->sumIV(compatkey, xtab[(compatkey[0]+rounds) % 4], item).substr(0,8));
 251                                 item.clear();
 252                         }
 253                         rounds++;
 254                 }
 255                 if (!item.empty())
 256                 {
 257                         hashies.push_back(Hash->sumIV(compatkey, xtab[(compatkey[0]+rounds) % 4], item).substr(0,8));
 258                 }
 259                 /* Stick them all together */
 260                 return irc::stringjoiner(":", hashies, 0, hashies.size() - 1).GetJoined();
 261         }
 262
 263         std::string SegmentIP(const irc::sockets::sockaddrs& ip, bool full)
 264         {
 265                 std::string bindata;
 266                 int hop1, hop2, hop3;
 267                 int len1, len2;
 268                 std::string rv;
 269                 if (ip.sa.sa_family == AF_INET6)
 270                 {
 271                         bindata = std::string((const char*)ip.in6.sin6_addr.s6_addr, 16);
 272                         hop1 = 8;
 273                         hop2 = 6;
 274                         hop3 = 4;
 275                         len1 = 6;
 276                         len2 = 4;
 277                         // pfx s1.s2.s3. (xxxx.xxxx or s4) sfx
 278                         //     6  4  4    9/6
 279                         rv.reserve(prefix.length() + 26 + suffix.length());
 280                 }
 281                 else
 282                 {
 283                         bindata = std::string((const char*)&ip.in4.sin_addr, 4);
 284                         hop1 = 3;
 285                         hop2 = 0;
 286                         hop3 = 2;
 287                         len1 = len2 = 3;
 288                         // pfx s1.s2. (xxx.xxx or s3) sfx
 289                         rv.reserve(prefix.length() + 15 + suffix.length());
 290                 }
 291
 292                 rv.append(prefix);
 293                 rv.append(SegmentCloak(bindata, 10, len1));
 294                 rv.append(1, '.');
 295                 bindata.erase(hop1);
 296                 rv.append(SegmentCloak(bindata, 11, len2));
 297                 if (hop2)
 298                 {
 299                         rv.append(1, '.');
 300                         bindata.erase(hop2);
 301                         rv.append(SegmentCloak(bindata, 12, len2));
 302                 }
 303
 304                 if (full)
 305                 {
 306                         rv.append(1, '.');
 307                         bindata.erase(hop3);
 308                         rv.append(SegmentCloak(bindata, 13, 6));
 309                         rv.append(suffix);
 310                 }
 311                 else
 312                 {
 313                         char buf[50];
 314                         if (ip.sa.sa_family == AF_INET6)
 315                         {
 316                                 snprintf(buf, 50, ".%02x%02x.%02x%02x%s",
 317                                         ip.in6.sin6_addr.s6_addr[2], ip.in6.sin6_addr.s6_addr[3],
 318                                         ip.in6.sin6_addr.s6_addr[0], ip.in6.sin6_addr.s6_addr[1], suffix.c_str());
 319                         }
 320                         else
 321                         {
 322                                 const unsigned char* ip4 = (const unsigned char*)&ip.in4.sin_addr;
 323                                 snprintf(buf, 50, ".%d.%d%s", ip4[1], ip4[0], suffix.c_str());
 324                         }
 325                         rv.append(buf);
 326                 }
 327                 return rv;
 328         }
 329
 330         ModResult OnCheckBan(User* user, Channel* chan, const std::string& mask)
 331         {
 332                 LocalUser* lu = IS_LOCAL(user);
 333                 if (!lu)
 334                         return MOD_RES_PASSTHRU;
 335
 336                 OnUserConnect(lu);
 337                 std::string* cloak = cu.ext.get(user);
 338                 /* Check if they have a cloaked host, but are not using it */
 339                 if (cloak && *cloak != user->dhost)
 340                 {
 341                         char cmask[MAXBUF];
 342                         snprintf(cmask, MAXBUF, "%s!%s@%s", user->nick.c_str(), user->ident.c_str(), cloak->c_str());
 343                         if (InspIRCd::Match(cmask,mask))
 344                                 return MOD_RES_DENY;
 345                 }
 346                 return MOD_RES_PASSTHRU;
 347         }
 348
 349         void Prioritize()
 350         {
 351                 /* Needs to be after m_banexception etc. */
 352                 ServerInstance->Modules->SetPriority(this, I_OnCheckBan, PRIORITY_LAST);
 353         }
 354
 355         // this unsets umode +x on every host change. If we are actually doing a +x
 356         // mode change, we will call SetMode back to true AFTER the host change is done.
 357         void OnChangeHost(User* u, const std::string& host)
 358         {
 359                 u->SetMode('x', false);
 360         }
 361
 362         ~ModuleCloaking()
 363         {
 364         }
 365
 366         Version GetVersion()
 367         {
 368                 std::string testcloak = "broken";
 369                 if (Hash)
 370                 {
 371                         switch (mode)
 372                         {
 373                                 case MODE_COMPAT_HOST:
 374                                         testcloak = prefix + "-" + Hash->sumIV(compatkey, xtab[0], "*").substr(0,10);
 375                                         break;
 376                                 case MODE_COMPAT_IPONLY:
 377                                         testcloak = Hash->sumIV(compatkey, xtab[0], "*").substr(0,10);
 378                                         break;
 379                                 case MODE_HALF_CLOAK:
 380                                         testcloak = prefix + SegmentCloak("*", 3, 8) + suffix;
 381                                         break;
 382                                 case MODE_OPAQUE:
 383                                         testcloak = prefix + SegmentCloak("*", 4, 8) + suffix;
 384                         }
 385                 }
 386                 return Version("Provides masking of user hostnames", VF_COMMON|VF_VENDOR, testcloak);
 387         }
 388
 389         void OnRehash(User* user)
 390         {
 391                 ConfigTag* tag = ServerInstance->Config->ConfValue("cloak");
 392                 prefix = tag->getString("prefix");
 393                 suffix = tag->getString("suffix", ".IP");
 394
 395                 std::string modestr = tag->getString("mode");
 396                 if (modestr == "compat-host")
 397                         mode = MODE_COMPAT_HOST;
 398                 else if (modestr == "compat-ip")
 399                         mode = MODE_COMPAT_IPONLY;
 400                 else if (modestr == "half")
 401                         mode = MODE_HALF_CLOAK;
 402                 else if (modestr == "full")
 403                         mode = MODE_OPAQUE;
 404                 else
 405                         throw ModuleException("Bad value for <cloak:mode>; must be one of compat-host, compat-ip, half, full");
 406
 407                 if (mode == MODE_COMPAT_HOST || mode == MODE_COMPAT_IPONLY)
 408                 {
 409                         bool lowercase = tag->getBool("lowercase");
 410
 411                         /* These are *not* using the need_positive parameter of ReadInteger -
 412                          * that will limit the valid values to only the positive values in a
 413                          * signed int. Instead, accept any value that fits into an int and
 414                          * cast it to an unsigned int. That will, a bit oddly, give us the full
 415                          * spectrum of an unsigned integer. - Special
 416                          *
 417                          * We must limit the keys or else we get different results on
 418                          * amd64/x86 boxes. - psychon */
 419                         const unsigned int limit = 0x80000000;
 420                         compatkey[0] = (unsigned int) tag->getInt("key1");
 421                         compatkey[1] = (unsigned int) tag->getInt("key2");
 422                         compatkey[2] = (unsigned int) tag->getInt("key3");
 423                         compatkey[3] = (unsigned int) tag->getInt("key4");
 424
 425                         if (!lowercase)
 426                         {
 427                                 xtab[0] = "F92E45D871BCA630";
 428                                 xtab[1] = "A1B9D80C72E653F4";
 429                                 xtab[2] = "1ABC078934DEF562";
 430                                 xtab[3] = "ABCDEF5678901234";
 431                         }
 432                         else
 433                         {
 434                                 xtab[0] = "f92e45d871bca630";
 435                                 xtab[1] = "a1b9d80c72e653f4";
 436                                 xtab[2] = "1abc078934def562";
 437                                 xtab[3] = "abcdef5678901234";
 438                         }
 439
 440                         if (prefix.empty())
 441                                 prefix = ServerInstance->Config->Network;
 442
 443                         if (!compatkey[0] || !compatkey[1] || !compatkey[2] || !compatkey[3] ||
 444                                 compatkey[0] >= limit || compatkey[1] >= limit || compatkey[2] >= limit || compatkey[3] >= limit)
 445                         {
 446                                 std::string detail;
 447                                 if (!compatkey[0] || compatkey[0] >= limit)
 448                                         detail = "<cloak:key1> is not valid, it may be set to a too high/low value, or it may not exist.";
 449                                 else if (!compatkey[1] || compatkey[1] >= limit)
 450                                         detail = "<cloak:key2> is not valid, it may be set to a too high/low value, or it may not exist.";
 451                                 else if (!compatkey[2] || compatkey[2] >= limit)
 452                                         detail = "<cloak:key3> is not valid, it may be set to a too high/low value, or it may not exist.";
 453                                 else if (!compatkey[3] || compatkey[3] >= limit)
 454                                         detail = "<cloak:key4> is not valid, it may be set to a too high/low value, or it may not exist.";
 455
 456                                 throw ModuleException("You have not defined cloak keys for m_cloaking!!! THIS IS INSECURE AND SHOULD BE CHECKED! - " + detail);
 457                         }
 458                 }
 459                 else
 460                 {
 461                         key = tag->getString("key");
 462                         if (key.empty() || key == "secret")
 463                                 throw ModuleException("You have not defined cloak keys for m_cloaking. Define <cloak:key> as a network-wide secret.");
 464                 }
 465         }
 466
 467         void OnUserConnect(LocalUser* dest)
 468         {
 469                 std::string* cloak = cu.ext.get(dest);
 470                 if (cloak)
 471                         return;
 472
 473                 std::string ipstr = dest->GetIPString();
 474                 std::string chost;
 475
 476                 switch (mode)
 477                 {
 478                         case MODE_COMPAT_HOST:
 479                         {
 480                                 if (ipstr != dest->host)
 481                                 {
 482                                         std::string tail = LastTwoDomainParts(dest->host);
 483
 484                                         /* Generate a cloak using specialized Hash */
 485                                         chost = prefix + "-" + Hash->sumIV(compatkey, xtab[(dest->host[0]) % 4], dest->host).substr(0,8) + tail;
 486
 487                                         /* Fix by brain - if the cloaked host is > the max length of a host (64 bytes
 488                                          * according to the DNS RFC) then they get cloaked as an IP.
 489                                          */
 490                                         if (chost.length() <= 64)
 491                                                 break;
 492                                 }
 493                                 // fall through to IP cloak
 494                         }
 495                         case MODE_COMPAT_IPONLY:
 496                                 if (dest->client_sa.sa.sa_family == AF_INET6)
 497                                         chost = CompatCloak6(ipstr.c_str());
 498                                 else
 499                                         chost = CompatCloak4(ipstr.c_str());
 500                                 break;
 501                         case MODE_HALF_CLOAK:
 502                         {
 503                                 if (ipstr != dest->host)
 504                                         chost = prefix + SegmentCloak(dest->host, 1, 6) + LastTwoDomainParts(dest->host);
 505                                 if (chost.empty() || chost.length() > 50)
 506                                         chost = SegmentIP(dest->client_sa, false);
 507                                 break;
 508                         }
 509                         case MODE_OPAQUE:
 510                         default:
 511                                 chost = SegmentIP(dest->client_sa, true);
 512                 }
 513                 cu.ext.set(dest,chost);
 514         }
 515
 516 };
 517
 518 MODULE_INIT(ModuleCloaking)