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