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 "commands/cmd_whois.h"
  16 #include "commands/cmd_stats.h"
  17 #include "socket.h"
  18 #include "xline.h"
  19 #include "../transport.h"
  20 #include "../m_hash.h"
  21 #include "socketengine.h"
  22
  23 #include "main.h"
  24 #include "utils.h"
  25 #include "treeserver.h"
  26 #include "link.h"
  27 #include "treesocket.h"
  28 #include "resolvers.h"
  29 #include "handshaketimer.h"
  30
  31 /* $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 */
  32
  33 const std::string& TreeSocket::GetOurChallenge()
  34 {
  35         return this->ourchallenge;
  36 }
  37
  38 void TreeSocket::SetOurChallenge(const std::string &c)
  39 {
  40         this->ourchallenge = c;
  41 }
  42
  43 const std::string& TreeSocket::GetTheirChallenge()
  44 {
  45         return this->theirchallenge;
  46 }
  47
  48 void TreeSocket::SetTheirChallenge(const std::string &c)
  49 {
  50         this->theirchallenge = c;
  51 }
  52
  53 std::string TreeSocket::MakePass(const std::string &password, const std::string &challenge)
  54 {
  55         /* This is a simple (maybe a bit hacky?) HMAC algorithm, thanks to jilles for
  56          * suggesting the use of HMAC to secure the password against various attacks.
  57          *
  58          * Note: If m_sha256.so is not loaded, we MUST fall back to plaintext with no
  59          *       HMAC challenge/response.
  60          */
  61         Module* sha256 = ServerInstance->Modules->Find("m_sha256.so");
  62         if (Utils->ChallengeResponse && sha256 && !challenge.empty())
  63         {
  64                 /* XXX: This is how HMAC is supposed to be done:
  65                  *
  66                  * sha256( (pass xor 0x5c) + sha256((pass xor 0x36) + m) )
  67                  *
  68                  * Note that we are encoding the hex hash, not the binary
  69                  * output of the hash which is slightly different to standard.
  70                  *
  71                  * 5c and 36 were chosen as part of the HMAC standard, because they
  72                  * flip the bits in a way likely to strengthen the function.
  73                  */
  74                 std::string hmac1, hmac2;
  75
  76                 for (size_t n = 0; n < password.length(); n++)
  77                 {
  78                         hmac1 += static_cast<char>(password[n] ^ 0x5C);
  79                         hmac2 += static_cast<char>(password[n] ^ 0x36);
  80                 }
  81
  82                 hmac2 += challenge;
  83                 HashResetRequest(Utils->Creator, sha256).Send();
  84                 hmac2 = HashSumRequest(Utils->Creator, sha256, hmac2).Send();
  85
  86                 HashResetRequest(Utils->Creator, sha256).Send();
  87                 std::string hmac = hmac1 + hmac2;
  88                 hmac = HashSumRequest(Utils->Creator, sha256, hmac).Send();
  89
  90                 return "HMAC-SHA256:"+ hmac;
  91         }
  92         else if (!challenge.empty() && !sha256)
  93                 ServerInstance->Logs->Log("m_spanningtree",DEFAULT,"Not authenticating to server using SHA256/HMAC because we don't have m_sha256 loaded!");
  94
  95         return password;
  96 }
  97
  98 std::string TreeSocket::RandString(unsigned int ilength)
  99 {
 100         char* randombuf = new char[ilength+1];
 101         std::string out;
 102 #ifndef WINDOWS
 103         int f = open("/dev/urandom", O_RDONLY, 0);
 104
 105         if (f >= 0)
 106         {
 107                 if (read(f, randombuf, ilength) < ilength)
 108                         ServerInstance->Logs->Log("m_spanningtree", DEFAULT, "Entropy source has gone predictable (did not return enough data)");
 109                 close(f);
 110         }
 111         else
 112 #endif
 113         {
 114                 for (unsigned int i = 0; i < ilength; i++)
 115                         randombuf[i] = rand();
 116         }
 117
 118         for (unsigned int i = 0; i < ilength; i++)
 119         {
 120                 char randchar = static_cast<char>(0x3F + (randombuf[i] & 0x3F));
 121                 out += randchar;
 122         }
 123
 124         delete[] randombuf;
 125         return out;
 126 }
 127
 128 bool TreeSocket::ComparePass(const Link& link, const std::string &theirs)
 129 {
 130         this->auth_fingerprint = !link.Fingerprint.empty();
 131         this->auth_challenge = !ourchallenge.empty() && !theirchallenge.empty();
 132
 133         const char* fp = NULL;
 134         if (GetHook())
 135                 fp = BufferedSocketFingerprintRequest(this, Utils->Creator, GetHook()).Send();
 136
 137         if (fp)
 138                 ServerInstance->Logs->Log("m_spanningtree", DEFAULT, std::string("Server SSL fingerprint ") + fp);
 139
 140         if (auth_fingerprint)
 141         {
 142                 /* Require fingerprint to exist and match */
 143                 if (!fp || link.Fingerprint != std::string(fp))
 144                         return false;
 145         }
 146
 147         if (auth_challenge)
 148         {
 149                 std::string our_hmac = MakePass(link.RecvPass, ourchallenge);
 150
 151                 /* Straight string compare of hashes */
 152                 return our_hmac == theirs;
 153         }
 154
 155         /* Straight string compare of plaintext */
 156         return link.RecvPass == theirs;
 157 }