src/modules/rlm_digest/rlm_digest.c

   1 /*
   2  * rlm_chap.c
   3  *
   4  * Version:  $Id$
   5  *
   6  *   This program is free software; you can redistribute it and/or modify
   7  *   it under the terms of the GNU General Public License as published by
   8  *   the Free Software Foundation; either version 2 of the License, or
   9  *   (at your option) any later version.
  10  *
  11  *   This program is distributed in the hope that it will be useful,
  12  *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  *   GNU General Public License for more details.
  15  *
  16  *   You should have received a copy of the GNU General Public License
  17  *   along with this program; if not, write to the Free Software
  18  *   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
  19  *
  20  * Copyright 2002  The FreeRADIUS server project
  21  * Copyright 2002  Alan DeKok <aland@ox.org>
  22  */
  23
  24 #include <freeradius-devel/autoconf.h>
  25
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29
  30 #include <freeradius-devel/radiusd.h>
  31 #include <freeradius-devel/modules.h>
  32
  33 static const char rcsid[] = "$Id$";
  34
  35 static int digest_authorize(void *instance, REQUEST *request)
  36 {
  37         VALUE_PAIR *vp;
  38
  39         /* quiet the compiler */
  40         instance = instance;
  41
  42         /*
  43          *      We need both of these attributes to do the authentication.
  44          */
  45         vp = pairfind(request->packet->vps, PW_DIGEST_RESPONSE);
  46         if (vp == NULL) {
  47                 return RLM_MODULE_NOOP;
  48         }
  49
  50         /*
  51          *      Check the sanity of the attribute.
  52          */
  53         if (vp->length != 32) {
  54                 DEBUG("ERROR: Received invalid Digest-Response attribute (length %d should be 32)", vp->length);
  55                 return RLM_MODULE_INVALID;
  56         }
  57
  58         /*
  59          *      We need these, too.
  60          */
  61         vp = pairfind(request->packet->vps, PW_DIGEST_ATTRIBUTES);
  62         if (vp == NULL) {
  63                 DEBUG("ERROR: Received Digest-Response without Digest-Attributes");
  64                 return RLM_MODULE_INVALID;
  65         }
  66
  67         /*
  68          *      Everything's OK, add a digest authentication type.
  69          */
  70         if (pairfind(request->config_items, PW_AUTHTYPE) == NULL) {
  71                 DEBUG("rlm_digest: Adding Auth-Type = DIGEST");
  72                 pairadd(&request->config_items,
  73                         pairmake("Auth-Type", "DIGEST", T_OP_EQ));
  74         }
  75
  76         return RLM_MODULE_OK;
  77 }
  78
  79 /*
  80  *      Perform all of the wondrous variants of digest authentication.
  81  */
  82 static int digest_authenticate(void *instance, REQUEST *request)
  83 {
  84         int i;
  85         size_t a1_len, a2_len, kd_len;
  86         uint8_t a1[(MAX_STRING_LEN + 1) * 5]; /* can be 5 attributes */
  87         uint8_t a2[(MAX_STRING_LEN + 1) * 3]; /* can be 3 attributes */
  88         uint8_t kd[(MAX_STRING_LEN + 1) * 5];
  89         uint8_t hash[16];       /* MD5 output */
  90         VALUE_PAIR *vp, *passwd, *algo;
  91         VALUE_PAIR *qop, *nonce;
  92
  93         instance = instance;    /* -Wunused */
  94
  95         /*
  96          *      We require access to the plain-text password.
  97          */
  98         passwd = pairfind(request->config_items, PW_DIGEST_HA1);
  99         if (passwd) {
 100                 if (passwd->length != 32) {
 101                         radlog(L_AUTH, "rlm_digest: Digest-HA1 has invalid length, authentication failed.");
 102                         return RLM_MODULE_INVALID;
 103                 }
 104         } else {
 105                 passwd = pairfind(request->config_items, PW_CLEARTEXT_PASSWORD);
 106         }
 107         if (!passwd) {
 108                 radlog(L_AUTH, "rlm_digest: Cleartext-Password or Digest-HA1 is required for authentication.");
 109                 return RLM_MODULE_INVALID;
 110         }
 111
 112         /*
 113          *      We need these, too.
 114          */
 115         vp = pairfind(request->packet->vps, PW_DIGEST_ATTRIBUTES);
 116         if (vp == NULL) {
 117                 DEBUG("ERROR: You set 'Auth-Type = Digest' for a request that did not contain any digest attributes!");
 118                 return RLM_MODULE_INVALID;
 119         }
 120
 121         /*
 122          *      Loop through the Digest-Attributes, sanity checking them.
 123          */
 124         DEBUG("    rlm_digest: Converting Digest-Attributes to something sane...");
 125         while (vp) {
 126                 int length = vp->length;
 127                 int attrlen;
 128                 uint8_t *p = &vp->vp_octets[0];
 129                 VALUE_PAIR *sub;
 130
 131                 /*
 132                  *      Until this stupidly encoded attribure is exhausted.
 133                  */
 134                 while (length > 0) {
 135                         /*
 136                          *      The attribute type must be valid
 137                          */
 138                         if ((p[0] == 0) || (p[0] > 10)) {
 139                                 DEBUG("ERROR: Received Digest-Attributes with invalid sub-attribute %d", p[0]);
 140                                 return RLM_MODULE_INVALID;
 141                         }
 142
 143                         attrlen = p[1]; /* stupid VSA format */
 144
 145                         /*
 146                          *      Too short.
 147                          */
 148                         if (attrlen < 3) {
 149                                 DEBUG("ERROR: Received Digest-Attributes with short sub-attribute %d, of length %d", p[0], attrlen);
 150                                 return RLM_MODULE_INVALID;
 151                         }
 152
 153                         /*
 154                          *      Too long.
 155                          */
 156                         if (attrlen > length) {
 157                                 DEBUG("ERROR: Received Digest-Attributes with long sub-attribute %d, of length %d", p[0], attrlen);
 158                                 return RLM_MODULE_INVALID;
 159                         }
 160
 161                         /*
 162                          *      Create a new attribute, broken out of
 163                          *      the stupid sub-attribute crap.
 164                          *
 165                          *      Didn't they know that VSA's exist?
 166                          */
 167                         sub = paircreate(PW_DIGEST_REALM - 1 + p[0],
 168                                          PW_TYPE_STRING);
 169                         if (!sub) {
 170                                 return RLM_MODULE_FAIL; /* out of memory */
 171                         }
 172                         memcpy(&sub->vp_octets[0], &p[2], attrlen - 2);
 173                         sub->vp_octets[attrlen - 2] = '\0';
 174                         sub->length = attrlen - 2;
 175
 176                         if (debug_flag) {
 177                           putchar('\t');
 178                           vp_print(stdout, sub);
 179                           putchar('\n');
 180                         }
 181
 182                         /*
 183                          *      And add it to the request pairs.
 184                          */
 185                         pairadd(&request->packet->vps, sub);
 186
 187                         /*
 188                          *      FIXME: Check for the existence
 189                          *      of the necessary attributes!
 190                          */
 191
 192                         length -= attrlen;
 193                         p += attrlen;
 194                 } /* loop over this one attribute */
 195
 196                 /*
 197                  *      Find the next one, if it exists.
 198                  */
 199                 vp = pairfind(vp->next, PW_DIGEST_ATTRIBUTES);
 200         }
 201
 202         /*
 203          *      We require access to the Digest-Nonce-Value
 204          */
 205         nonce = pairfind(request->packet->vps, PW_DIGEST_NONCE);
 206         if (!nonce) {
 207                 DEBUG("ERROR: No Digest-Nonce: Cannot perform Digest authentication");
 208                 return RLM_MODULE_INVALID;
 209         }
 210
 211         /*
 212          *      A1 = Digest-User-Name ":" Realm ":" Password
 213          */
 214         vp = pairfind(request->packet->vps, PW_DIGEST_USER_NAME);
 215         if (!vp) {
 216                 DEBUG("ERROR: No Digest-User-Name: Cannot perform Digest authentication");
 217                 return RLM_MODULE_INVALID;
 218         }
 219         memcpy(&a1[0], &vp->vp_octets[0], vp->length);
 220         a1_len = vp->length;
 221
 222         a1[a1_len] = ':';
 223         a1_len++;
 224
 225         vp = pairfind(request->packet->vps, PW_DIGEST_REALM);
 226         if (!vp) {
 227                 DEBUG("ERROR: No Digest-Realm: Cannot perform Digest authentication");
 228                 return RLM_MODULE_INVALID;
 229         }
 230         memcpy(&a1[a1_len], &vp->vp_octets[0], vp->length);
 231         a1_len += vp->length;
 232
 233         a1[a1_len] = ':';
 234         a1_len++;
 235
 236         if (passwd->attribute == PW_CLEARTEXT_PASSWORD) {
 237                 memcpy(&a1[a1_len], &passwd->vp_octets[0], passwd->length);
 238                 a1_len += passwd->length;
 239                 a1[a1_len] = '\0';
 240                 DEBUG2("A1 = %s", a1);
 241         } else {
 242                 a1[a1_len] = '\0';
 243                 DEBUG2("A1 = %s (using Digest-HA1)", a1);
 244                 a1_len = 16;
 245         }
 246
 247         /*
 248          *      See which variant we calculate.
 249          *      Assume MD5 if no Digest-Algorithm attribute received
 250          */
 251         algo = pairfind(request->packet->vps, PW_DIGEST_ALGORITHM);
 252         if ((algo == NULL) ||
 253             (strcasecmp(algo->vp_strvalue, "MD5") == 0)) {
 254                 /*
 255                  *      Set A1 to Digest-HA1 if no User-Password found
 256                  */
 257                 if (passwd->attribute == PW_DIGEST_HA1) {
 258                         lrad_hex2bin(passwd->vp_strvalue, &a1[0], 16);
 259                 }
 260
 261         } else if (strcasecmp(algo->vp_strvalue, "MD5-sess") == 0) {
 262                 /*
 263                  *      K1 = H(A1) : Digest-Nonce ... : H(A2)
 264                  *
 265                  *      If we find Digest-HA1, we assume it contains
 266                  *      H(A1).
 267                  */
 268                 if (passwd->attribute == PW_CLEARTEXT_PASSWORD) {
 269                         librad_md5_calc(hash, &a1[0], a1_len);
 270                         lrad_bin2hex(hash, &a1[0], 16);
 271                 } else {        /* MUST be Digest-HA1 */
 272                         memcpy(&a1[0], passwd->vp_strvalue, 32);
 273                 }
 274                 a1_len = 32;
 275
 276                 a1[a1_len] = ':';
 277                 a1_len++;
 278
 279                 /*
 280                  *      Tack on the Digest-Nonce. Length must be even
 281                  */
 282                 if ((nonce->length & 1) != 0) {
 283                         DEBUG("ERROR: Received Digest-Nonce hex string with invalid length: Cannot perform Digest authentication");
 284                         return RLM_MODULE_INVALID;
 285                 }
 286                 memcpy(&a1[a1_len], &nonce->vp_octets[0], nonce->length);
 287                 a1_len += nonce->length;
 288
 289                 a1[a1_len] = ':';
 290                 a1_len++;
 291
 292                 vp = pairfind(request->packet->vps, PW_DIGEST_CNONCE);
 293                 if (!vp) {
 294                         DEBUG("ERROR: No Digest-CNonce: Cannot perform Digest authentication");
 295                         return RLM_MODULE_INVALID;
 296                 }
 297
 298                 /*
 299                  *      Digest-CNonce length must be even
 300                  */
 301                 if ((vp->length & 1) != 0) {
 302                         DEBUG("ERROR: Received Digest-CNonce hex string with invalid length: Cannot perform Digest authentication");
 303                         return RLM_MODULE_INVALID;
 304                 }
 305                 memcpy(&a1[a1_len], &vp->vp_octets[0], vp->length);
 306                 a1_len += vp->length;
 307
 308         } else if ((algo != NULL) &&
 309                    (strcasecmp(algo->vp_strvalue, "MD5") != 0)) {
 310                 /*
 311                  *      We check for "MD5-sess" and "MD5".
 312                  *      Anything else is an error.
 313                  */
 314                 DEBUG("ERROR: Unknown Digest-Algorithm \"%s\": Cannot perform Digest authentication", vp->vp_strvalue);
 315                 return RLM_MODULE_INVALID;
 316         }
 317
 318         /*
 319          *      A2 = Digest-Method ":" Digest-URI
 320          */
 321         vp = pairfind(request->packet->vps, PW_DIGEST_METHOD);
 322         if (!vp) {
 323                 DEBUG("ERROR: No Digest-Method: Cannot perform Digest authentication");
 324                 return RLM_MODULE_INVALID;
 325         }
 326         memcpy(&a2[0], &vp->vp_octets[0], vp->length);
 327         a2_len = vp->length;
 328
 329         a2[a2_len] = ':';
 330         a2_len++;
 331
 332         vp = pairfind(request->packet->vps, PW_DIGEST_URI);
 333         if (!vp) {
 334                 DEBUG("ERROR: No Digest-URI: Cannot perform Digest authentication");
 335                 return RLM_MODULE_INVALID;
 336         }
 337         memcpy(&a2[a2_len], &vp->vp_octets[0], vp->length);
 338         a2_len += vp->length;
 339
 340         /*
 341          *  QOP is "auth-int", tack on ": Digest-Body-Digest"
 342          */
 343         qop = pairfind(request->packet->vps, PW_DIGEST_QOP);
 344         if ((qop != NULL) &&
 345             (strcasecmp(qop->vp_strvalue, "auth-int") == 0)) {
 346                 VALUE_PAIR *body;
 347
 348                 /*
 349                  *      Add in Digest-Body-Digest
 350                  */
 351                 a2[a2_len] = ':';
 352                 a2_len++;
 353
 354                 /*
 355                  *  Must be a hex representation of an MD5 digest.
 356                  */
 357                 body = pairfind(request->packet->vps, PW_DIGEST_BODY_DIGEST);
 358                 if (!body) {
 359                         DEBUG("ERROR: No Digest-Body-Digest: Cannot perform Digest authentication");
 360                         return RLM_MODULE_INVALID;
 361                 }
 362
 363                 if ((a2_len + body->length) > sizeof(a2)) {
 364                         DEBUG("ERROR: Digest-Body-Digest is too long");
 365                         return RLM_MODULE_INVALID;
 366                 }
 367
 368                 memcpy(a2 + a2_len, body->vp_octets, body->length);
 369                 a2_len += body->length;
 370
 371         } else if ((qop != NULL) &&
 372                    (strcasecmp(qop->vp_strvalue, "auth") != 0)) {
 373                 DEBUG("ERROR: Unknown Digest-QOP \"%s\": Cannot perform Digest authentication", qop->vp_strvalue);
 374                 return RLM_MODULE_INVALID;
 375         }
 376
 377         a2[a2_len] = '\0';
 378         DEBUG2("A2 = %s", a2);
 379
 380         /*
 381          *     KD = H(A1) : Digest-Nonce ... : H(A2).
 382          *     Compute MD5 if Digest-Algorithm == "MD5-Sess",
 383          *     or if we found a User-Password.
 384          */
 385         if (((algo != NULL) &&
 386              (strcasecmp(algo->vp_strvalue, "MD5-Sess") == 0)) ||
 387             (passwd->attribute == PW_CLEARTEXT_PASSWORD)) {
 388                 a1[a1_len] = '\0';
 389                 librad_md5_calc(&hash[0], &a1[0], a1_len);
 390         } else {
 391                 memcpy(&hash[0], &a1[0], a1_len);
 392         }
 393         lrad_bin2hex(hash, kd, sizeof(hash));
 394
 395 #ifndef NDEBUG
 396         if (debug_flag) {
 397                 printf("H(A1) = ");
 398                 for (i = 0; i < 16; i++) {
 399                         printf("%02x", hash[i]);
 400                 }
 401                 printf("\n");
 402         }
 403 #endif
 404         kd_len = 32;
 405
 406         kd[kd_len] = ':';
 407         kd_len++;
 408
 409         memcpy(&kd[kd_len], nonce->vp_octets, nonce->length);
 410         kd_len += nonce->length;
 411
 412         /*
 413          *      No QOP defined.  Do RFC 2069 compatibility.
 414          */
 415         if (!qop) {
 416                 /*
 417                  *      Do nothing here.
 418                  */
 419
 420         } else {                /* Digest-QOP MUST be "auth" or "auth-int" */
 421                 /*
 422                  *      Tack on ":" Digest-Nonce-Count ":" Digest-CNonce
 423                  *             ":" Digest-QOP
 424                  */
 425                 kd[kd_len] = ':';
 426                 kd_len++;
 427
 428                 vp = pairfind(request->packet->vps, PW_DIGEST_NONCE_COUNT);
 429                 if (!vp) {
 430                         DEBUG("ERROR: No Digest-Nonce-Count: Cannot perform Digest authentication");
 431                         return RLM_MODULE_INVALID;
 432                 }
 433                 memcpy(&kd[kd_len], &vp->vp_octets[0], vp->length);
 434                 kd_len += vp->length;
 435
 436                 kd[kd_len] = ':';
 437                 kd_len++;
 438
 439                 vp = pairfind(request->packet->vps, PW_DIGEST_CNONCE);
 440                 if (!vp) {
 441                         DEBUG("ERROR: No Digest-CNonce: Cannot perform Digest authentication");
 442                         return RLM_MODULE_INVALID;
 443                 }
 444                 memcpy(&kd[kd_len], &vp->vp_octets[0], vp->length);
 445                 kd_len += vp->length;
 446
 447                 kd[kd_len] = ':';
 448                 kd_len++;
 449
 450                 memcpy(&kd[kd_len], &qop->vp_octets[0], qop->length);
 451                 kd_len += qop->length;
 452         }
 453
 454         /*
 455          *      Tack on ":" H(A2)
 456          */
 457         kd[kd_len] = ':';
 458         kd_len++;
 459
 460         librad_md5_calc(&hash[0], &a2[0], a2_len);
 461
 462         lrad_bin2hex(hash, kd + kd_len, sizeof(hash));
 463
 464 #ifndef NDEBUG
 465         if (debug_flag) {
 466                 printf("H(A2) = ");
 467                 for (i = 0; i < 16; i++) {
 468                         printf("%02x", hash[i]);
 469                 }
 470                 printf("\n");
 471         }
 472 #endif
 473         kd_len += 32;
 474
 475         kd[kd_len] = 0;
 476
 477         DEBUG2("KD = %s\n", &kd[0]);
 478
 479         /*
 480          *      Take the hash of KD.
 481          */
 482         librad_md5_calc(&hash[0], &kd[0], kd_len);
 483         memcpy(&kd[0], &hash[0], 16);
 484
 485         /*
 486          *      Get the binary value of Digest-Response
 487          */
 488         vp = pairfind(request->packet->vps, PW_DIGEST_RESPONSE);
 489         if (!vp) {
 490                 DEBUG("ERROR: No Digest-Response attribute in the request.  Cannot perform digest authentication");
 491                 return RLM_MODULE_INVALID;
 492         }
 493
 494         lrad_hex2bin(&vp->vp_octets[0], &hash[0], vp->length >> 1);
 495
 496 #ifndef NDEBUG
 497         if (debug_flag) {
 498                 printf("EXPECTED ");
 499                 for (i = 0; i < 16; i++) {
 500                         printf("%02x", kd[i]);
 501                 }
 502                 printf("\n");
 503
 504                 printf("RECEIVED ");
 505                 for (i = 0; i < 16; i++) {
 506                         printf("%02x", hash[i]);
 507                 }
 508                 printf("\n");
 509         }
 510 #endif
 511
 512         /*
 513          *  And finally, compare the digest in the packet with KD.
 514          */
 515         if (memcmp(&kd[0], &hash[0], 16) == 0) {
 516                 return RLM_MODULE_OK;
 517         }
 518
 519         DEBUG("rlm_digest: FAILED authentication");
 520         return RLM_MODULE_REJECT;
 521 }
 522
 523 /*
 524  *      The module name should be the only globally exported symbol.
 525  *      That is, everything else should be 'static'.
 526  *
 527  *      If the module needs to temporarily modify it's instantiation
 528  *      data, the type should be changed to RLM_TYPE_THREAD_UNSAFE.
 529  *      The server will then take care of ensuring that the module
 530  *      is single-threaded.
 531  */
 532 module_t rlm_digest = {
 533         RLM_MODULE_INIT,
 534         "digest",
 535         0,                              /* type */
 536         NULL,                           /* instantiation */
 537         NULL,                           /* detach */
 538         {
 539                 digest_authenticate,    /* authentication */
 540                 digest_authorize,       /* authorization */
 541                 NULL,                   /* preaccounting */
 542                 NULL,                   /* accounting */
 543                 NULL,                   /* checksimul */
 544                 NULL,                   /* pre-proxy */
 545                 NULL,                   /* post-proxy */
 546                 NULL                    /* post-auth */
 547         },
 548 };