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 "client.h"
  38 #include "ircd.h"
  39 #include "modules.h"
  40 #include "numeric.h"
  41 #include "send.h"
  42 #include "s_conf.h"
  43 #include "msg.h"
  44 #include "parse.h"
  45 #include "match.h"
  46 #include "logger.h"
  47 #include "s_user.h"
  48 #include "cache.h"
  49 #include "s_newconf.h"
  50
  51 #define CHALLENGE_WIDTH BUFSIZE - (NICKLEN + HOSTLEN + 12)
  52 #define CHALLENGE_EXPIRES       180     /* 180 seconds should be more than long enough */
  53 #define CHALLENGE_SECRET_LENGTH 128     /* how long our challenge secret should be */
  54
  55 #ifndef HAVE_LIBCRYPTO
  56
  57 static const char challenge_desc[] = "Does nothing as OpenSSL was not enabled.";
  58
  59 /* Maybe this should be an error or something?-davidt */
  60 /* now it is    -larne  */
  61 static int challenge_load(void)
  62 {
  63         sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
  64                 "Challenge module not loaded because OpenSSL is not available.");
  65         ilog(L_MAIN, "Challenge module not loaded because OpenSSL is not available.");
  66         return -1;
  67 }
  68
  69 DECLARE_MODULE_AV2(challenge, challenge_load, NULL, NULL, NULL, NULL, NULL, NULL, challenge_desc);
  70 #else
  71
  72 static const char challenge_desc[] =
  73         "Provides the challenge-response facility used for becoming an IRC operator";
  74
  75 static void m_challenge(struct MsgBuf *, struct Client *, struct Client *, int, const char **);
  76
  77 /* We have openssl support, so include /CHALLENGE */
  78 struct Message challenge_msgtab = {
  79         "CHALLENGE", 0, 0, 0, 0,
  80         {mg_unreg, {m_challenge, 2}, mg_ignore, mg_ignore, mg_ignore, {m_challenge, 2}}
  81 };
  82
  83 mapi_clist_av1 challenge_clist[] = { &challenge_msgtab, NULL };
  84
  85 DECLARE_MODULE_AV2(challenge, NULL, NULL, challenge_clist, NULL, NULL, NULL, NULL, challenge_desc);
  86
  87 static bool generate_challenge(char **r_challenge, char **r_response, RSA * key);
  88
  89 static void
  90 cleanup_challenge(struct Client *target_p)
  91 {
  92         if(target_p->localClient == NULL)
  93                 return;
  94
  95         rb_free(target_p->localClient->challenge);
  96         rb_free(target_p->user->opername);
  97         target_p->localClient->challenge = NULL;
  98         target_p->user->opername = NULL;
  99         target_p->localClient->chal_time = 0;
 100 }
 101
 102 /*
 103  * m_challenge - generate RSA challenge for wouldbe oper
 104  * parv[1] = operator to challenge for, or +response
 105  */
 106 static void
 107 m_challenge(struct MsgBuf *msgbuf_p, 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 (ConfigFileEntry.oper_secure_only && !IsSecureClient(source_p))
 117         {
 118                 sendto_one_notice(source_p, ":You must be using a secure connection to /CHALLENGE on this server");
 119                 if (ConfigFileEntry.failed_oper_notice)
 120                 {
 121                         sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
 122                                         "Failed CHALLENGE attempt - missing secure connection by %s (%s@%s)",
 123                                         source_p->name, source_p->username, source_p->host);
 124                 }
 125                 return;
 126         }
 127
 128         /* if theyre an oper, reprint oper motd and ignore */
 129         if(IsOper(source_p))
 130         {
 131                 sendto_one(source_p, form_str(RPL_YOUREOPER), me.name, source_p->name);
 132                 send_oper_motd(source_p);
 133                 return;
 134         }
 135
 136         if(*parv[1] == '+')
 137         {
 138                 /* Ignore it if we aren't expecting this... -A1kmm */
 139                 if(!source_p->localClient->challenge)
 140                         return;
 141
 142                 if((rb_current_time() - source_p->localClient->chal_time) > CHALLENGE_EXPIRES)
 143                 {
 144                         sendto_one(source_p, form_str(ERR_PASSWDMISMATCH), me.name, source_p->name);
 145                         ilog(L_FOPER, "EXPIRED CHALLENGE (%s) by (%s!%s@%s) (%s)",
 146                              source_p->user->opername, source_p->name,
 147                              source_p->username, source_p->host, source_p->sockhost);
 148
 149                         if(ConfigFileEntry.failed_oper_notice)
 150                                 sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
 151                                                      "Expired CHALLENGE attempt by %s (%s@%s)",
 152                                                      source_p->name, source_p->username,
 153                                                      source_p->host);
 154                         cleanup_challenge(source_p);
 155                         return;
 156                 }
 157
 158                 parv[1]++;
 159                 b_response = rb_base64_decode((const unsigned char *)parv[1], strlen(parv[1]), &len);
 160
 161                 if(len != SHA_DIGEST_LENGTH ||
 162                    memcmp(source_p->localClient->challenge, b_response, SHA_DIGEST_LENGTH))
 163                 {
 164                         sendto_one(source_p, form_str(ERR_PASSWDMISMATCH), me.name, source_p->name);
 165                         ilog(L_FOPER, "FAILED CHALLENGE (%s) by (%s!%s@%s) (%s)",
 166                              source_p->user->opername, source_p->name,
 167                              source_p->username, source_p->host, source_p->sockhost);
 168
 169                         if(ConfigFileEntry.failed_oper_notice)
 170                                 sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
 171                                                      "Failed CHALLENGE attempt by %s (%s@%s)",
 172                                                      source_p->name, source_p->username,
 173                                                      source_p->host);
 174
 175                         rb_free(b_response);
 176                         cleanup_challenge(source_p);
 177                         return;
 178                 }
 179
 180                 rb_free(b_response);
 181
 182                 oper_p = find_oper_conf(source_p->username, source_p->orighost,
 183                                         source_p->sockhost,
 184                                         source_p->user->opername);
 185
 186                 if(oper_p == NULL)
 187                 {
 188                         sendto_one_numeric(source_p, ERR_NOOPERHOST, form_str(ERR_NOOPERHOST));
 189                         ilog(L_FOPER, "FAILED OPER (%s) by (%s!%s@%s) (%s)",
 190                              source_p->user->opername, source_p->name,
 191                              source_p->username, source_p->host,
 192                              source_p->sockhost);
 193
 194                         if(ConfigFileEntry.failed_oper_notice)
 195                                 sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
 196                                                      "Failed CHALLENGE attempt - host mismatch by %s (%s@%s)",
 197                                                      source_p->name, source_p->username,
 198                                                      source_p->host);
 199                         return;
 200                 }
 201
 202                 cleanup_challenge(source_p);
 203
 204                 oper_up(source_p, oper_p);
 205
 206                 ilog(L_OPERED, "OPER %s by %s!%s@%s (%s)",
 207                      source_p->user->opername, source_p->name,
 208                      source_p->username, source_p->host, source_p->sockhost);
 209                 return;
 210         }
 211
 212         cleanup_challenge(source_p);
 213
 214         oper_p = find_oper_conf(source_p->username, source_p->orighost,
 215                                 source_p->sockhost, parv[1]);
 216
 217         if(oper_p == NULL)
 218         {
 219                 sendto_one_numeric(source_p, ERR_NOOPERHOST, form_str(ERR_NOOPERHOST));
 220                 ilog(L_FOPER, "FAILED OPER (%s) by (%s!%s@%s) (%s)",
 221                      parv[1], source_p->name,
 222                      source_p->username, source_p->host, source_p->sockhost);
 223
 224                 if(ConfigFileEntry.failed_oper_notice)
 225                         sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
 226                                              "Failed CHALLENGE attempt - host mismatch by %s (%s@%s)",
 227                                              source_p->name, source_p->username, source_p->host);
 228                 return;
 229         }
 230
 231         if(!oper_p->rsa_pubkey)
 232         {
 233                 sendto_one_notice(source_p, ":I'm sorry, PK authentication is not enabled for your oper{} block.");
 234                 return;
 235         }
 236
 237         if(IsOperConfNeedSSL(oper_p) && !IsSecureClient(source_p))
 238         {
 239                 sendto_one_numeric(source_p, ERR_NOOPERHOST, form_str(ERR_NOOPERHOST));
 240                 ilog(L_FOPER, "FAILED CHALLENGE (%s) by (%s!%s@%s) (%s) -- requires SSL/TLS",
 241                      parv[1], source_p->name, source_p->username, source_p->host,
 242                      source_p->sockhost);
 243
 244                 if(ConfigFileEntry.failed_oper_notice)
 245                 {
 246                         sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
 247                                              "Failed CHALLENGE attempt - missing SSL/TLS by %s (%s@%s)",
 248                                              source_p->name, source_p->username, source_p->host);
 249                 }
 250                 return;
 251         }
 252
 253         if (oper_p->certfp != NULL)
 254         {
 255                 if (source_p->certfp == NULL || rb_strcasecmp(source_p->certfp, oper_p->certfp))
 256                 {
 257                         sendto_one_numeric(source_p, ERR_NOOPERHOST, form_str(ERR_NOOPERHOST));
 258                         ilog(L_FOPER, "FAILED OPER (%s) by (%s!%s@%s) (%s) -- client certificate fingerprint mismatch",
 259                              parv[1], source_p->name,
 260                              source_p->username, source_p->host, source_p->sockhost);
 261
 262                         if(ConfigFileEntry.failed_oper_notice)
 263                         {
 264                                 sendto_realops_snomask(SNO_GENERAL, L_NETWIDE,
 265                                                      "Failed OPER attempt - client certificate fingerprint mismatch by %s (%s@%s)",
 266                                                      source_p->name, source_p->username, source_p->host);
 267                         }
 268                         return;
 269                 }
 270         }
 271
 272         if(generate_challenge(&challenge, &(source_p->localClient->challenge), oper_p->rsa_pubkey))
 273         {
 274                 char *chal = challenge;
 275                 source_p->localClient->chal_time = rb_current_time();
 276                 for(;;)
 277                 {
 278                         cnt = rb_strlcpy(chal_line, chal, CHALLENGE_WIDTH);
 279                         sendto_one(source_p, form_str(RPL_RSACHALLENGE2), me.name, source_p->name, chal_line);
 280                         if(cnt > CHALLENGE_WIDTH)
 281                                 chal += CHALLENGE_WIDTH - 1;
 282                         else
 283                                 break;
 284
 285                 }
 286                 sendto_one(source_p, form_str(RPL_ENDOFRSACHALLENGE2),
 287                            me.name, source_p->name);
 288                 rb_free(challenge);
 289                 source_p->user->opername = rb_strdup(oper_p->name);
 290         }
 291         else
 292                 sendto_one_notice(source_p, ":Failed to generate challenge.");
 293 }
 294
 295 static bool
 296 generate_challenge(char **r_challenge, char **r_response, RSA * rsa)
 297 {
 298         SHA_CTX ctx;
 299         unsigned char secret[CHALLENGE_SECRET_LENGTH], *tmp;
 300         unsigned long length;
 301         unsigned long e = 0;
 302         unsigned long cnt = 0;
 303         int ret;
 304
 305         if(!rsa)
 306                 return false;
 307         if(rb_get_random(secret, CHALLENGE_SECRET_LENGTH))
 308         {
 309                 SHA1_Init(&ctx);
 310                 SHA1_Update(&ctx, (uint8_t *)secret, CHALLENGE_SECRET_LENGTH);
 311                 *r_response = malloc(SHA_DIGEST_LENGTH);
 312                 SHA1_Final((uint8_t *)*r_response, &ctx);
 313
 314                 length = RSA_size(rsa);
 315                 tmp = rb_malloc(length);
 316                 ret = RSA_public_encrypt(CHALLENGE_SECRET_LENGTH, secret, tmp, rsa, RSA_PKCS1_OAEP_PADDING);
 317
 318                 if(ret >= 0)
 319                 {
 320                         *r_challenge = (char *)rb_base64_encode(tmp, ret);
 321                         rb_free(tmp);
 322                         return true;
 323                 }
 324
 325                 rb_free(tmp);
 326                 rb_free(*r_response);
 327                 *r_response = NULL;
 328         }
 329
 330         ERR_load_crypto_strings();
 331         while ((cnt < 100) && (e = ERR_get_error()))
 332         {
 333                 ilog(L_MAIN, "SSL error: %s", ERR_error_string(e, 0));
 334                 cnt++;
 335         }
 336
 337         return false;
 338 }
 339
 340 #endif /* HAVE_LIBCRYPTO */