modules/m_challenge.c

   1 /*
   2  *  ircd-ratbox: A slightly useful ircd.
   3  *  m_challenge.c: Allows an IRC Operator to securely authenticate.
   4  *
   5  *  Copyright (C) 1990 Jarkko Oikarinen and University of Oulu, Co Center
   6  *  Copyright (C) 1996-2002 Hybrid Development Team
   7  *  Copyright (C) 2002-2005 ircd-ratbox development team
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License as published by
  11  *  the Free Software Foundation; either version 2 of the License, or
  12  *  (at your option) any later version.
  13  *
  14  *  This program is distributed in the hope that it will be useful,
  15  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  *  GNU General Public License for more details.
  18  *
  19  *  You should have received a copy of the GNU General Public License
  20  *  along with this program; if not, write to the Free Software
  21  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307
  22  *  USA
  23  */
  24
  25 #include "stdinc.h"
  26
  27 #ifdef HAVE_LIBCRYPTO
  28 #include <openssl/pem.h>
  29 #include <openssl/rand.h>
  30 #include <openssl/rsa.h>
  31 #include <openssl/md5.h>
  32 #include <openssl/bn.h>
  33 #include <openssl/evp.h>
  34 #include <openssl/err.h>
  35 #endif
  36
  37 #include "memory.h"
  38 #include "client.h"
  39 #include "ircd.h"
  40 #include "modules.h"
  41 #include "numeric.h"
  42 #include "send.h"
  43 #include "s_conf.h"
  44 #include "msg.h"
  45 #include "parse.h"
  46 #include "irc_string.h"
  47 #include "s_log.h"
  48 #include "s_user.h"
  49 #include "cache.h"
  50 #include "s_newconf.h"
  51
  52 #define CHALLENGE_WIDTH BUFSIZE - (NICKLEN + HOSTLEN + 12)
  53 #define CHALLENGE_EXPIRES       180     /* 180 seconds should be more than long enough */
  54 #define CHALLENGE_SECRET_LENGTH 128     /* how long our challenge secret should be */
  55
  56 #ifndef HAVE_LIBCRYPTO
  57 /* Maybe this should be an error or something?-davidt */
  58 /* now it is    -larne  */
  59 static int      challenge_load(void)
  60 {
  61 #ifndef STATIC_MODULES
  62         sendto_realops_snomask(SNO_GENERAL, L_ALL,
  63                 "Challenge module not loaded because OpenSSL is not available.");
  64         ilog(L_MAIN, "Challenge module not loaded because OpenSSL is not available.");
  65         return -1;
  66 #else
  67         return 0;
  68 #endif
  69 }
  70
  71 DECLARE_MODULE_AV1(challenge, challenge_load, NULL, NULL, NULL, NULL, "$Revision: 26 $");
  72 #else
  73
  74 static int m_challenge(struct Client *, struct Client *, int, const char **);
  75
  76 /* We have openssl support, so include /CHALLENGE */
  77 struct Message challenge_msgtab = {
  78         "CHALLENGE", 0, 0, 0, MFLG_SLOW,
  79         {mg_unreg, {m_challenge, 2}, mg_ignore, mg_ignore, mg_ignore, {m_challenge, 2}}
  80 };
  81
  82 mapi_clist_av1 challenge_clist[] = { &challenge_msgtab, NULL };
  83 DECLARE_MODULE_AV1(challenge, NULL, NULL, challenge_clist, NULL, NULL, "$Revision: 26 $");
  84
  85 static int generate_challenge(char **r_challenge, char **r_response, RSA * key);
  86
  87 static void
  88 cleanup_challenge(struct Client *target_p)
  89 {
  90         if(target_p->localClient == NULL)
  91                 return;
  92
  93         MyFree(target_p->localClient->challenge);
  94         MyFree(target_p->localClient->opername);
  95         target_p->localClient->challenge = NULL;
  96         target_p->localClient->opername = NULL;
  97         target_p->localClient->chal_time = 0;
  98 }
  99
 100 /*
 101  * m_challenge - generate RSA challenge for wouldbe oper
 102  * parv[0] = sender prefix
 103  * parv[1] = operator to challenge for, or +response
 104  *
 105  */
 106 static int
 107 m_challenge(struct Client *client_p, struct Client *source_p, int parc, const char *parv[])
 108 {
 109         struct oper_conf *oper_p;
 110         char *challenge = NULL; /* to placate gcc */
 111         char chal_line[CHALLENGE_WIDTH];
 112         unsigned char *b_response;
 113         size_t cnt;
 114         int len = 0;
 115
 116         /* if theyre an oper, reprint oper motd and ignore */
 117         if(IsOper(source_p))
 118         {
 119                 sendto_one(source_p, form_str(RPL_YOUREOPER), me.name, source_p->name);
 120                 send_oper_motd(source_p);
 121                 return 0;
 122         }
 123
 124         if(*parv[1] == '+')
 125         {
 126                 /* Ignore it if we aren't expecting this... -A1kmm */
 127                 if(!source_p->localClient->challenge)
 128                         return 0;
 129
 130                 if((CurrentTime - source_p->localClient->chal_time) > CHALLENGE_EXPIRES)
 131                 {
 132                         sendto_one(source_p, form_str(ERR_PASSWDMISMATCH), me.name, source_p->name);
 133                         ilog(L_FOPER, "EXPIRED CHALLENGE (%s) by (%s!%s@%s) (%s)",
 134                              source_p->localClient->opername, source_p->name,
 135                              source_p->username, source_p->host, source_p->sockhost);
 136
 137                         if(ConfigFileEntry.failed_oper_notice)
 138                                 sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
 139                                                      "Expired CHALLENGE attempt by %s (%s@%s)",
 140                                                      source_p->name, source_p->username,
 141                                                      source_p->host);
 142                         cleanup_challenge(source_p);
 143                         return 0;
 144                 }
 145
 146                 b_response = ircd_base64_decode((const unsigned char *)++parv[1], strlen(parv[1]), &len);
 147
 148                 if(len != SHA_DIGEST_LENGTH ||
 149                    memcmp(source_p->localClient->challenge, b_response, SHA_DIGEST_LENGTH))
 150                 {
 151                         sendto_one(source_p, form_str(ERR_PASSWDMISMATCH), me.name, source_p->name);
 152                         ilog(L_FOPER, "FAILED CHALLENGE (%s) by (%s!%s@%s) (%s)",
 153                              source_p->localClient->opername, source_p->name,
 154                              source_p->username, source_p->host, source_p->sockhost);
 155
 156                         if(ConfigFileEntry.failed_oper_notice)
 157                                 sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
 158                                                      "Failed CHALLENGE attempt by %s (%s@%s)",
 159                                                      source_p->name, source_p->username,
 160                                                      source_p->host);
 161
 162                         MyFree(b_response);
 163                         cleanup_challenge(source_p);
 164                         return 0;
 165                 }
 166
 167                 MyFree(b_response);
 168
 169                 oper_p = find_oper_conf(source_p->username, source_p->orighost,
 170                                         source_p->sockhost,
 171                                         source_p->localClient->opername);
 172
 173                 if(oper_p == NULL)
 174                 {
 175                         sendto_one(source_p, form_str(ERR_NOOPERHOST),
 176                                    me.name, source_p->name);
 177                         ilog(L_FOPER, "FAILED OPER (%s) by (%s!%s@%s) (%s)",
 178                              source_p->localClient->opername, source_p->name,
 179                              source_p->username, source_p->host,
 180                              source_p->sockhost);
 181
 182                         if(ConfigFileEntry.failed_oper_notice)
 183                                 sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
 184                                                      "Failed CHALLENGE attempt - host mismatch by %s (%s@%s)",
 185                                                      source_p->name, source_p->username,
 186                                                      source_p->host);
 187                         return 0;
 188                 }
 189
 190                 cleanup_challenge(source_p);
 191
 192                 oper_up(source_p, oper_p);
 193
 194                 ilog(L_OPERED, "OPER %s by %s!%s@%s (%s)",
 195                      source_p->localClient->opername, source_p->name,
 196                      source_p->username, source_p->host, source_p->sockhost);
 197                 return 0;
 198         }
 199
 200         cleanup_challenge(source_p);
 201
 202         oper_p = find_oper_conf(source_p->username, source_p->orighost,
 203                                 source_p->sockhost, parv[1]);
 204
 205         if(oper_p == NULL)
 206         {
 207                 sendto_one(source_p, form_str(ERR_NOOPERHOST), me.name, source_p->name);
 208                 ilog(L_FOPER, "FAILED OPER (%s) by (%s!%s@%s) (%s)",
 209                      parv[1], source_p->name,
 210                      source_p->username, source_p->host, source_p->sockhost);
 211
 212                 if(ConfigFileEntry.failed_oper_notice)
 213                         sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
 214                                              "Failed CHALLENGE attempt - host mismatch by %s (%s@%s)",
 215                                              source_p->name, source_p->username, source_p->host);
 216                 return 0;
 217         }
 218
 219         if(!oper_p->rsa_pubkey)
 220         {
 221                 sendto_one(source_p, ":%s NOTICE %s :I'm sorry, PK authentication "
 222                            "is not enabled for your oper{} block.", me.name, parv[0]);
 223                 return 0;
 224         }
 225
 226         if(!generate_challenge(&challenge, &(source_p->localClient->challenge), oper_p->rsa_pubkey))
 227         {
 228                 char *chal = challenge;
 229                 source_p->localClient->chal_time = CurrentTime;
 230                 for(;;)
 231                 {
 232                         cnt = strlcpy(chal_line, chal, CHALLENGE_WIDTH);
 233                         sendto_one(source_p, form_str(RPL_RSACHALLENGE2), me.name, source_p->name, chal_line);
 234                         if(cnt > CHALLENGE_WIDTH)
 235                                 chal += CHALLENGE_WIDTH - 1;
 236                         else
 237                                 break;
 238
 239                 }
 240                 sendto_one(source_p, form_str(RPL_ENDOFRSACHALLENGE2),
 241                            me.name, source_p->name);
 242                 MyFree(challenge);
 243                 DupString(source_p->localClient->opername, oper_p->name);
 244         }
 245         else
 246                 sendto_one_notice(source_p, ":Failed to generate challenge.");
 247
 248         return 0;
 249 }
 250
 251 static int
 252 get_randomness(unsigned char *buf, int length)
 253 {
 254         /* Seed OpenSSL PRNG with EGD enthropy pool -kre */
 255         if(ConfigFileEntry.use_egd && (ConfigFileEntry.egdpool_path != NULL))
 256         {
 257                 if(RAND_egd(ConfigFileEntry.egdpool_path) == -1)
 258                         return -1;
 259         }
 260
 261         if(RAND_status())
 262         {
 263                 if(RAND_bytes(buf, length) > 0)
 264                         return 1;
 265         }
 266         else {
 267                 if(RAND_pseudo_bytes(buf, length) >= 0)
 268                         return 1;
 269         }
 270         return 0;
 271 }
 272
 273 static int
 274 generate_challenge(char **r_challenge, char **r_response, RSA * rsa)
 275 {
 276         SHA_CTX ctx;
 277         unsigned char secret[CHALLENGE_SECRET_LENGTH], *tmp;
 278         unsigned long length;
 279         unsigned long e = 0;
 280         unsigned long cnt = 0;
 281         int ret;
 282
 283         if(!rsa)
 284                 return -1;
 285         if(get_randomness(secret, CHALLENGE_SECRET_LENGTH))
 286         {
 287                 SHA1_Init(&ctx);
 288                 SHA1_Update(&ctx, (u_int8_t *)secret, CHALLENGE_SECRET_LENGTH);
 289                 *r_response = MyMalloc(SHA_DIGEST_LENGTH);
 290                 SHA1_Final((u_int8_t *)*r_response, &ctx);
 291
 292                 length = RSA_size(rsa);
 293                 tmp = MyMalloc(length);
 294                 ret = RSA_public_encrypt(CHALLENGE_SECRET_LENGTH, secret, tmp, rsa, RSA_PKCS1_OAEP_PADDING);
 295
 296                 if (ret >= 0)
 297                 {
 298                         *r_challenge = (char *)ircd_base64_encode(tmp, ret);
 299                         MyFree(tmp);
 300                         return 0;
 301                 }
 302                 MyFree(tmp);
 303                 MyFree(*r_response);
 304                 *r_response = NULL;
 305         }
 306
 307         ERR_load_crypto_strings();
 308         while ((cnt < 100) && (e = ERR_get_error()))
 309         {
 310                 ilog(L_MAIN, "SSL error: %s", ERR_error_string(e, 0));
 311                 cnt++;
 312         }
 313
 314         return (-1);
 315 }
 316
 317 #endif /* HAVE_LIBCRYPTO */