src/modules/m_spanningtree/hmac.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 "socket.h"
  16 #include "xline.h"
  17 #include "../m_hash.h"
  18 #include "../ssl.h"
  19 #include "socketengine.h"
  20
  21 #include "main.h"
  22 #include "utils.h"
  23 #include "treeserver.h"
  24 #include "link.h"
  25 #include "treesocket.h"
  26 #include "resolvers.h"
  27
  28 const std::string& TreeSocket::GetOurChallenge()
  29 {
  30         return capab->ourchallenge;
  31 }
  32
  33 void TreeSocket::SetOurChallenge(const std::string &c)
  34 {
  35         capab->ourchallenge = c;
  36 }
  37
  38 const std::string& TreeSocket::GetTheirChallenge()
  39 {
  40         return capab->theirchallenge;
  41 }
  42
  43 void TreeSocket::SetTheirChallenge(const std::string &c)
  44 {
  45         capab->theirchallenge = c;
  46 }
  47
  48 std::string TreeSocket::MakePass(const std::string &password, const std::string &challenge)
  49 {
  50         /* This is a simple (maybe a bit hacky?) HMAC algorithm, thanks to jilles for
  51          * suggesting the use of HMAC to secure the password against various attacks.
  52          *
  53          * Note: If m_sha256.so is not loaded, we MUST fall back to plaintext with no
  54          *       HMAC challenge/response.
  55          */
  56         HashProvider* sha256 = ServerInstance->Modules->FindDataService<HashProvider>("hash/sha256");
  57         if (Utils->ChallengeResponse && sha256 && !challenge.empty())
  58         {
  59                 /* This is how HMAC is supposed to be done:
  60                  *
  61                  * sha256( (pass xor 0x5c) + sha256((pass xor 0x36) + m) )
  62                  *
  63                  * 5c and 36 were chosen as part of the HMAC standard, because they
  64                  * flip the bits in a way likely to strengthen the function.
  65                  */
  66                 std::string hmac1, hmac2;
  67
  68                 for (size_t n = 0; n < password.length(); n++)
  69                 {
  70                         hmac1.push_back(static_cast<char>(password[n] ^ 0x5C));
  71                         hmac2.push_back(static_cast<char>(password[n] ^ 0x36));
  72                 }
  73
  74                 if (proto_version >= 1202)
  75                 {
  76                         hmac2.append(challenge);
  77                         std::string hmac = sha256->hexsum(hmac1 + sha256->sum(hmac2));
  78
  79                         return "AUTH:" + hmac;
  80                 }
  81                 else
  82                 {
  83                         // version 1.2 used a weaker HMAC, using hex output in the intermediate step
  84                         hmac2.append(challenge);
  85                         hmac2 = sha256->hexsum(hmac2);
  86
  87                         std::string hmac = hmac1 + hmac2;
  88                         hmac = sha256->hexsum(hmac);
  89
  90                         return "HMAC-SHA256:"+ hmac;
  91                 }
  92         }
  93         else if (!challenge.empty() && !sha256)
  94                 ServerInstance->Logs->Log("m_spanningtree",DEFAULT,"Not authenticating to server using SHA256/HMAC because we don't have m_sha256 loaded!");
  95
  96         return password;
  97 }
  98
  99 std::string TreeSocket::RandString(unsigned int ilength)
 100 {
 101         char* randombuf = new char[ilength+1];
 102         std::string out;
 103 #ifndef WINDOWS
 104         int f = open("/dev/urandom", O_RDONLY, 0);
 105
 106         if (f >= 0)
 107         {
 108                 if (read(f, randombuf, ilength) < (int)ilength)
 109                         ServerInstance->Logs->Log("m_spanningtree", DEFAULT, "Entropy source has gone predictable (did not return enough data)");
 110                 close(f);
 111         }
 112         else
 113 #endif
 114         {
 115                 for (unsigned int i = 0; i < ilength; i++)
 116                         randombuf[i] = rand();
 117         }
 118
 119         for (unsigned int i = 0; i < ilength; i++)
 120         {
 121                 char randchar = static_cast<char>(0x3F + (randombuf[i] & 0x3F));
 122                 out += randchar;
 123         }
 124
 125         delete[] randombuf;
 126         return out;
 127 }
 128
 129 bool TreeSocket::ComparePass(const Link& link, const std::string &theirs)
 130 {
 131         capab->auth_fingerprint = !link.Fingerprint.empty();
 132         capab->auth_challenge = !capab->ourchallenge.empty() && !capab->theirchallenge.empty();
 133
 134         std::string fp;
 135         if (GetIOHook())
 136         {
 137                 SocketCertificateRequest req(this, Utils->Creator, GetIOHook());
 138                 if (req.cert)
 139                 {
 140                         fp = req.cert->GetFingerprint();
 141                 }
 142         }
 143
 144         if (capab->auth_challenge)
 145         {
 146                 std::string our_hmac = MakePass(link.RecvPass, capab->ourchallenge);
 147
 148                 /* Straight string compare of hashes */
 149                 if (our_hmac != theirs)
 150                         return false;
 151         }
 152         else
 153         {
 154                 /* Straight string compare of plaintext */
 155                 if (link.RecvPass != theirs)
 156                         return false;
 157         }
 158
 159         if (capab->auth_fingerprint)
 160         {
 161                 /* Require fingerprint to exist and match */
 162                 if (link.Fingerprint != fp)
 163                 {
 164                         ServerInstance->SNO->WriteToSnoMask('l',"Invalid SSL fingerprint on link %s: need \"%s\" got \"%s\"",
 165                                 link.Name.c_str(), link.Fingerprint.c_str(), fp.c_str());
 166                         SendError("Provided invalid SSL fingerprint " + fp + " - expected " + link.Fingerprint);
 167                         return false;
 168                 }
 169         }
 170         else if (!fp.empty())
 171         {
 172                 ServerInstance->SNO->WriteToSnoMask('l', "SSL fingerprint for link %s is \"%s\". "
 173                         "You can improve security by specifying this in <link:fingerprint>.", link.Name.c_str(), fp.c_str());
 174         }
 175         return true;
 176 }