src/src/auths/spa.c

   1 /* $Cambridge: exim/src/src/auths/spa.c,v 1.1 2004/10/07 13:10:01 ph10 Exp $ */
   2
   3 /*************************************************
   4 *     Exim - an Internet mail transport agent    *
   5 *************************************************/
   6
   7 /* Copyright (c) University of Cambridge 1995 - 2004 */
   8 /* See the file NOTICE for conditions of use and distribution. */
   9
  10 /* This file, which provides support for Microsoft's Secure Password
  11 Authentication, was contributed by Marc Prud'hommeaux. Tom Kistner added SPA
  12 server support. I (PH) have only modified it in very trivial ways.
  13
  14 References:
  15   http://www.innovation.ch/java/ntlm.html
  16   http://www.kuro5hin.org/story/2002/4/28/1436/66154
  17
  18  * It seems that some systems have existing but different definitions of some
  19  * of the following types. I received a complaint about "int16" causing
  20  * compilation problems. So I (PH) have renamed them all, to be on the safe
  21  * side, by adding 'x' on the end. See auths/auth-spa.h.
  22
  23  * typedef signed short int16;
  24  * typedef unsigned short uint16;
  25  * typedef unsigned uint32;
  26  * typedef unsigned char  uint8;
  27
  28 07-August-2003: PH: Patched up the code to avoid assert bombouts for stupid
  29                     input data. Find appropriate comment by grepping for "PH".
  30 */
  31
  32
  33 #include "../exim.h"
  34 #include "spa.h"
  35
  36 /* #define DEBUG_SPA */
  37
  38 #ifdef DEBUG_SPA
  39 #define DSPA(x,y,z)   debug_printf(x,y,z)
  40 #else
  41 #define DSPA(x,y,z)
  42 #endif
  43
  44 /* Options specific to the spa authentication mechanism. */
  45
  46 optionlist auth_spa_options[] = {
  47   { "client_domain",             opt_stringptr,
  48       (void *)(offsetof(auth_spa_options_block, spa_domain)) },
  49   { "client_password",           opt_stringptr,
  50       (void *)(offsetof(auth_spa_options_block, spa_password)) },
  51   { "client_username",           opt_stringptr,
  52       (void *)(offsetof(auth_spa_options_block, spa_username)) },
  53   { "server_password",           opt_stringptr,
  54       (void *)(offsetof(auth_spa_options_block, spa_serverpassword)) }
  55 };
  56
  57 /* Size of the options list. An extern variable has to be used so that its
  58 address can appear in the tables drtables.c. */
  59
  60 int auth_spa_options_count =
  61   sizeof(auth_spa_options)/sizeof(optionlist);
  62
  63 /* Default private options block for the contidion authentication method. */
  64
  65 auth_spa_options_block auth_spa_option_defaults = {
  66   NULL,              /* spa_password */
  67   NULL,              /* spa_username */
  68   NULL,              /* spa_domain */
  69   NULL               /* spa_serverpassword (for server side use) */
  70 };
  71
  72
  73 /*************************************************
  74 *          Initialization entry point            *
  75 *************************************************/
  76
  77 /* Called for each instance, after its options have been read, to
  78 enable consistency checks to be done, or anything else that needs
  79 to be set up. */
  80
  81 void
  82 auth_spa_init(auth_instance *ablock)
  83 {
  84 auth_spa_options_block *ob =
  85   (auth_spa_options_block *)(ablock->options_block);
  86
  87 /* The public name defaults to the authenticator name */
  88
  89 if (ablock->public_name == NULL) ablock->public_name = ablock->name;
  90
  91 /* Both username and password must be set for a client */
  92
  93 if ((ob->spa_username == NULL) != (ob->spa_password == NULL))
  94   log_write(0, LOG_PANIC_DIE|LOG_CONFIG_FOR, "%s authenticator:\n  "
  95       "one of client_username and client_password cannot be set without "
  96       "the other", ablock->name);
  97 ablock->client = ob->spa_username != NULL;
  98
  99 /* For a server we have just one option */
 100
 101 ablock->server = ob->spa_serverpassword != NULL;
 102 }
 103
 104
 105
 106 /*************************************************
 107 *             Server entry point                 *
 108 *************************************************/
 109
 110 /* For interface, see auths/README */
 111
 112 #define CVAL(buf,pos) (((unsigned char *)(buf))[pos])
 113 #define PVAL(buf,pos) ((unsigned)CVAL(buf,pos))
 114 #define SVAL(buf,pos) (PVAL(buf,pos)|PVAL(buf,(pos)+1)<<8)
 115 #define IVAL(buf,pos) (SVAL(buf,pos)|SVAL(buf,(pos)+2)<<16)
 116
 117 int
 118 auth_spa_server(auth_instance *ablock, uschar *data)
 119 {
 120 auth_spa_options_block *ob = (auth_spa_options_block *)(ablock->options_block);
 121 uint8x lmRespData[24];
 122 uint8x ntRespData[24];
 123 SPAAuthRequest request;
 124 SPAAuthChallenge challenge;
 125 SPAAuthResponse  response;
 126 SPAAuthResponse  *responseptr = &response;
 127 uschar msgbuf[2048];
 128 uschar *clearpass;
 129
 130 /* send a 334, MS Exchange style, and grab the client's request */
 131
 132 if (auth_get_no64_data(&data, US"NTLM supported") != OK)
 133   {
 134   /* something borked */
 135   return FAIL;
 136   }
 137
 138 if (spa_base64_to_bits((char *)(&request), (const char *)(data)) < 0)
 139   {
 140   DEBUG(D_auth) debug_printf("auth_spa_server(): bad base64 data in "
 141   "request: %s\n", data);
 142   return FAIL;
 143   }
 144
 145 /* create a challenge and send it back */
 146
 147 spa_build_auth_challenge(&request,&challenge);
 148 spa_bits_to_base64 (msgbuf, (unsigned char*)&challenge,
 149     spa_request_length(&challenge));
 150
 151 if (auth_get_no64_data(&data, msgbuf) != OK)
 152   {
 153   /* something borked */
 154   return FAIL;
 155   }
 156
 157 /* dump client response */
 158 if (spa_base64_to_bits((char *)(&response), (const char *)(data)) < 0)
 159   {
 160   DEBUG(D_auth) debug_printf("auth_spa_server(): bad base64 data in "
 161   "response: %s\n", data);
 162   return FAIL;
 163   }
 164
 165 /* get username and put it in $1 */
 166
 167 /***************************************************************
 168 PH 07-Aug-2003: The original code here was this:
 169
 170 Ustrcpy(msgbuf, unicodeToString(((char*)responseptr) +
 171   IVAL(&responseptr->uUser.offset,0),
 172   SVAL(&responseptr->uUser.len,0)/2) );
 173
 174 However, if the response data is too long, unicodeToString bombs out on
 175 an assertion failure. It uses a 1024 fixed buffer. Bombing out is not a good
 176 idea. It's too messy to try to rework that function to return an error because
 177 it is called from a number of other places in the auth-spa.c module. Instead,
 178 since it is a very small function, I reproduce its code here, with a size check
 179 that causes failure if the size of msgbuf is exceeded. ****/
 180
 181   {
 182   int i;
 183   char *p = ((char*)responseptr) + IVAL(&responseptr->uUser.offset,0);
 184   int len = SVAL(&responseptr->uUser.len,0)/2;
 185
 186   if (len + 1 >= sizeof(msgbuf)) return FAIL;
 187   for (i = 0; i < len; ++i)
 188     {
 189     msgbuf[i] = *p & 0x7f;
 190     p += 2;
 191     }
 192   msgbuf[i] = 0;
 193   }
 194
 195 /***************************************************************/
 196
 197 expand_nstring[1] = msgbuf;
 198 expand_nlength[1] = Ustrlen(msgbuf);
 199 expand_nmax = 1;
 200
 201 /* look up password */
 202
 203 clearpass = expand_string(ob->spa_serverpassword);
 204 if (clearpass == NULL)
 205   {
 206   if (expand_string_forcedfail)
 207     {
 208     DEBUG(D_auth) debug_printf("auth_spa_server(): forced failure while "
 209       "expanding spa_serverpassword\n");
 210     return FAIL;
 211     }
 212   else
 213     {
 214     DEBUG(D_auth) debug_printf("auth_spa_server(): error while expanding "
 215       "spa_serverpassword: %s\n", expand_string_message);
 216     return DEFER;
 217     }
 218   }
 219
 220 /* create local hash copy */
 221
 222 spa_smb_encrypt (clearpass, challenge.challengeData, lmRespData);
 223 spa_smb_nt_encrypt (clearpass, challenge.challengeData, ntRespData);
 224
 225 /* compare NT hash (LM may not be available) */
 226
 227 if (memcmp(ntRespData,
 228       ((unsigned char*)responseptr)+IVAL(&responseptr->ntResponse.offset,0),
 229       24) == 0)
 230   /* success. we have a winner. */
 231   return OK;
 232
 233 return FAIL;
 234 }
 235
 236
 237 /*************************************************
 238 *              Client entry point                *
 239 *************************************************/
 240
 241 /* For interface, see auths/README */
 242
 243 int
 244 auth_spa_client(
 245   auth_instance *ablock,                 /* authenticator block */
 246   smtp_inblock *inblock,                 /* connection inblock */
 247   smtp_outblock *outblock,               /* connection outblock */
 248   int timeout,                           /* command timeout */
 249   uschar *buffer,                        /* buffer for reading response */
 250   int buffsize)                          /* size of buffer */
 251 {
 252        auth_spa_options_block *ob =
 253                (auth_spa_options_block *)(ablock->options_block);
 254        SPAAuthRequest   request;
 255        SPAAuthChallenge challenge;
 256        SPAAuthResponse  response;
 257        char msgbuf[2048];
 258        char *domain = NULL;
 259        char *username, *password;
 260
 261     if (smtp_write_command(outblock, FALSE, "AUTH %s\r\n",
 262          ablock->public_name) < 0)
 263                return FAIL_SEND;
 264
 265        /* wait for the 3XX OK message */
 266        if (!smtp_read_response(inblock, (uschar *)buffer, buffsize, '3', timeout))
 267                return FAIL;
 268
 269        /* Code added by PH to expand the options */
 270
 271        username = CS expand_string(ob->spa_username);
 272        if (username == NULL)
 273          {
 274          string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
 275            "authenticator: %s", ob->spa_username, ablock->name,
 276            expand_string_message);
 277          return ERROR;
 278          }
 279
 280        password = CS expand_string(ob->spa_password);
 281        if (password == NULL)
 282          {
 283          string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
 284            "authenticator: %s", ob->spa_password, ablock->name,
 285            expand_string_message);
 286          return ERROR;
 287          }
 288
 289        if (ob->spa_domain != NULL)
 290          {
 291          domain = CS expand_string(ob->spa_domain);
 292          if (domain == NULL)
 293            {
 294            string_format(buffer, buffsize, "expansion of \"%s\" failed in %s "
 295              "authenticator: %s", ob->spa_domain, ablock->name,
 296              expand_string_message);
 297            return ERROR;
 298            }
 299          }
 300
 301        /* Original code */
 302
 303        DSPA("\n\n%s authenticator: using domain %s\n\n",
 304                ablock->name, domain);
 305
 306        spa_build_auth_request (&request, CS username, domain);
 307        spa_bits_to_base64 (US msgbuf, (unsigned char*)&request,
 308                spa_request_length(&request));
 309
 310        DSPA("\n\n%s authenticator: sending request (%s)\n\n", ablock->name,
 311                msgbuf);
 312
 313        /* send the encrypted password */
 314        if (smtp_write_command(outblock, FALSE, "%s\r\n", msgbuf) < 0)
 315                return FAIL_SEND;
 316
 317        /* wait for the auth challenge */
 318        if (!smtp_read_response(inblock, (uschar *)buffer, buffsize, '3', timeout))
 319                return FAIL;
 320
 321        /* convert the challenge into the challenge struct */
 322        DSPA("\n\n%s authenticator: challenge (%s)\n\n",
 323                ablock->name, buffer + 4);
 324        spa_base64_to_bits ((char *)(&challenge), (const char *)(buffer + 4));
 325
 326        spa_build_auth_response (&challenge, &response,
 327                CS username, CS password);
 328        spa_bits_to_base64 (US msgbuf, (unsigned char*)&response,
 329                spa_request_length(&response));
 330        DSPA("\n\n%s authenticator: challenge response (%s)\n\n", ablock->name,
 331                msgbuf);
 332
 333        /* send the challenge response */
 334        if (smtp_write_command(outblock, FALSE, "%s\r\n", msgbuf) < 0)
 335                return FAIL_SEND;
 336
 337        /* If we receive a success response from the server, authentication
 338        has succeeded. There may be more data to send, but is there any point
 339        in provoking an error here? */
 340        if (smtp_read_response(inblock, US buffer, buffsize, '2', timeout))
 341                return OK;
 342
 343        /* Not a success response. If errno != 0 there is some kind of transmission
 344        error. Otherwise, check the response code in the buffer. If it starts with
 345        '3', more data is expected. */
 346        if (errno != 0 || buffer[0] != '3')
 347                return FAIL;
 348
 349        return FAIL;
 350 }
 351
 352 /* End of spa.c */