src/modules/m_spanningtree/hmac.cpp

   1 /*       +------------------------------------+
   2  *       | Inspire Internet Relay Chat Daemon |
   3  *       +------------------------------------+
   4  *
   5  *  InspIRCd: (C) 2002-2009 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 /* $ModDep: m_spanningtree/resolvers.h m_spanningtree/main.h m_spanningtree/utils.h m_spanningtree/treeserver.h m_spanningtree/link.h m_spanningtree/treesocket.h m_hash.h */
  29
  30 const std::string& TreeSocket::GetOurChallenge()
  31 {
  32         return this->ourchallenge;
  33 }
  34
  35 void TreeSocket::SetOurChallenge(const std::string &c)
  36 {
  37         this->ourchallenge = c;
  38 }
  39
  40 const std::string& TreeSocket::GetTheirChallenge()
  41 {
  42         return this->theirchallenge;
  43 }
  44
  45 void TreeSocket::SetTheirChallenge(const std::string &c)
  46 {
  47         this->theirchallenge = c;
  48 }
  49
  50 std::string TreeSocket::MakePass(const std::string &password, const std::string &challenge)
  51 {
  52         /* This is a simple (maybe a bit hacky?) HMAC algorithm, thanks to jilles for
  53          * suggesting the use of HMAC to secure the password against various attacks.
  54          *
  55          * Note: If m_sha256.so is not loaded, we MUST fall back to plaintext with no
  56          *       HMAC challenge/response.
  57          */
  58         Module* sha256 = ServerInstance->Modules->Find("m_sha256.so");
  59         if (Utils->ChallengeResponse && sha256 && !challenge.empty())
  60         {
  61                 /* XXX: This is how HMAC is supposed to be done:
  62                  *
  63                  * sha256( (pass xor 0x5c) + sha256((pass xor 0x36) + m) )
  64                  *
  65                  * Note that we are encoding the hex hash, not the binary
  66                  * output of the hash which is slightly different to standard.
  67                  *
  68                  * 5c and 36 were chosen as part of the HMAC standard, because they
  69                  * flip the bits in a way likely to strengthen the function.
  70                  */
  71                 std::string hmac1, hmac2;
  72
  73                 for (size_t n = 0; n < password.length(); n++)
  74                 {
  75                         hmac1 += static_cast<char>(password[n] ^ 0x5C);
  76                         hmac2 += static_cast<char>(password[n] ^ 0x36);
  77                 }
  78
  79                 hmac2 += challenge;
  80                 hmac2 = HashRequest(Utils->Creator, sha256, hmac2).hex();
  81
  82                 std::string hmac = hmac1 + hmac2;
  83                 hmac = HashRequest(Utils->Creator, sha256, hmac).hex();
  84
  85                 return "HMAC-SHA256:"+ hmac;
  86         }
  87         else if (!challenge.empty() && !sha256)
  88                 ServerInstance->Logs->Log("m_spanningtree",DEFAULT,"Not authenticating to server using SHA256/HMAC because we don't have m_sha256 loaded!");
  89
  90         return password;
  91 }
  92
  93 std::string TreeSocket::RandString(unsigned int ilength)
  94 {
  95         char* randombuf = new char[ilength+1];
  96         std::string out;
  97 #ifndef WINDOWS
  98         int f = open("/dev/urandom", O_RDONLY, 0);
  99
 100         if (f >= 0)
 101         {
 102                 if (read(f, randombuf, ilength) < (int)ilength)
 103                         ServerInstance->Logs->Log("m_spanningtree", DEFAULT, "Entropy source has gone predictable (did not return enough data)");
 104                 close(f);
 105         }
 106         else
 107 #endif
 108         {
 109                 for (unsigned int i = 0; i < ilength; i++)
 110                         randombuf[i] = rand();
 111         }
 112
 113         for (unsigned int i = 0; i < ilength; i++)
 114         {
 115                 char randchar = static_cast<char>(0x3F + (randombuf[i] & 0x3F));
 116                 out += randchar;
 117         }
 118
 119         delete[] randombuf;
 120         return out;
 121 }
 122
 123 bool TreeSocket::ComparePass(const Link& link, const std::string &theirs)
 124 {
 125         this->auth_fingerprint = !link.Fingerprint.empty();
 126         this->auth_challenge = !ourchallenge.empty() && !theirchallenge.empty();
 127
 128         std::string fp;
 129         if (GetIOHook())
 130         {
 131                 SSLCertificateRequest req(this, Utils->Creator);
 132                 if (req.cert)
 133                 {
 134                         fp = req.cert->GetFingerprint();
 135                 }
 136         }
 137
 138         if (auth_challenge)
 139         {
 140                 std::string our_hmac = MakePass(link.RecvPass, ourchallenge);
 141
 142                 /* Straight string compare of hashes */
 143                 if (our_hmac != theirs)
 144                         return false;
 145         }
 146         else
 147         {
 148                 /* Straight string compare of plaintext */
 149                 if (link.RecvPass != theirs)
 150                         return false;
 151         }
 152
 153         if (auth_fingerprint)
 154         {
 155                 /* Require fingerprint to exist and match */
 156                 if (link.Fingerprint != fp)
 157                 {
 158                         ServerInstance->SNO->WriteToSnoMask('l',"Invalid SSL fingerprint on link %s: need '%s' got '%s'",
 159                                 link.Name.c_str(), link.Fingerprint.c_str(), fp.c_str());
 160                         SendError("Provided invalid SSL fingerprint " + fp + " - expected " + link.Fingerprint);
 161                         return false;
 162                 }
 163         }
 164         else if (!fp.empty())
 165         {
 166                 ServerInstance->SNO->WriteToSnoMask('l', "SSL fingerprint for link %s is %s", link.Name.c_str(), fp.c_str());
 167         }
 168         return true;
 169 }