src/auth/digest/auth_digest.cc

   1 /*
   2  * $Id$
   3  *
   4  * DEBUG: section 29    Authenticator
   5  * AUTHOR: Robert Collins
   6  *
   7  * SQUID Internet Object Cache  http://squid.nlanr.net/Squid/
   8  * ----------------------------------------------------------
   9  *
  10  *  Squid is the result of efforts by numerous individuals from the
  11  *  Internet community.  Development is led by Duane Wessels of the
  12  *  National Laboratory for Applied Network Research and funded by the
  13  *  National Science Foundation.  Squid is Copyrighted (C) 1998 by
  14  *  the Regents of the University of California.  Please see the
  15  *  COPYRIGHT file for full details.  Squid incorporates software
  16  *  developed and/or copyrighted by other sources.  Please see the
  17  *  CREDITS file for full details.
  18  *
  19  *  This program is free software; you can redistribute it and/or modify
  20  *  it under the terms of the GNU General Public License as published by
  21  *  the Free Software Foundation; either version 2 of the License, or
  22  *  (at your option) any later version.
  23  *
  24  *  This program is distributed in the hope that it will be useful,
  25  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  26  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  27  *  GNU General Public License for more details.
  28  *
  29  *  You should have received a copy of the GNU General Public License
  30  *  along with this program; if not, write to the Free Software
  31  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111, USA.
  32  *
  33  */
  34
  35 /* The functions in this file handle authentication.
  36  * They DO NOT perform access control or auditing.
  37  * See acl.c for access control and client_side.c for auditing */
  38
  39
  40 #include "squid.h"
  41 #include "rfc2617.h"
  42 #include "auth/digest/auth_digest.h"
  43 #include "auth/digest/Scheme.h"
  44 #include "auth/digest/User.h"
  45 #include "auth/digest/UserRequest.h"
  46 #include "auth/Gadgets.h"
  47 #include "auth/State.h"
  48 #include "base64.h"
  49 #include "event.h"
  50 #include "mgr/Registration.h"
  51 #include "Store.h"
  52 #include "HttpRequest.h"
  53 #include "HttpReply.h"
  54 #include "wordlist.h"
  55 #include "SquidTime.h"
  56
  57 /* Digest Scheme */
  58
  59 static AUTHSSTATS authenticateDigestStats;
  60
  61 helper *digestauthenticators = NULL;
  62
  63 static hash_table *digest_nonce_cache;
  64
  65 static int authdigest_initialised = 0;
  66 static MemAllocator *digest_nonce_pool = NULL;
  67
  68 enum http_digest_attr_type {
  69     DIGEST_USERNAME,
  70     DIGEST_REALM,
  71     DIGEST_QOP,
  72     DIGEST_ALGORITHM,
  73     DIGEST_URI,
  74     DIGEST_NONCE,
  75     DIGEST_NC,
  76     DIGEST_CNONCE,
  77     DIGEST_RESPONSE,
  78     DIGEST_ENUM_END
  79 };
  80
  81 static const HttpHeaderFieldAttrs DigestAttrs[DIGEST_ENUM_END] = {
  82     {"username",  (http_hdr_type)DIGEST_USERNAME},
  83     {"realm", (http_hdr_type)DIGEST_REALM},
  84     {"qop", (http_hdr_type)DIGEST_QOP},
  85     {"algorithm", (http_hdr_type)DIGEST_ALGORITHM},
  86     {"uri", (http_hdr_type)DIGEST_URI},
  87     {"nonce", (http_hdr_type)DIGEST_NONCE},
  88     {"nc", (http_hdr_type)DIGEST_NC},
  89     {"cnonce", (http_hdr_type)DIGEST_CNONCE},
  90     {"response", (http_hdr_type)DIGEST_RESPONSE},
  91 };
  92
  93 static HttpHeaderFieldInfo *DigestFieldsInfo = NULL;
  94
  95 /*
  96  *
  97  * Nonce Functions
  98  *
  99  */
 100
 101 static void authenticateDigestNonceCacheCleanup(void *data);
 102 static digest_nonce_h *authenticateDigestNonceFindNonce(const char *nonceb64);
 103 static digest_nonce_h *authenticateDigestNonceNew(void);
 104 static void authenticateDigestNonceDelete(digest_nonce_h * nonce);
 105 static void authenticateDigestNonceSetup(void);
 106 static int authDigestNonceIsStale(digest_nonce_h * nonce);
 107 static void authDigestNonceEncode(digest_nonce_h * nonce);
 108 static void authDigestNonceLink(digest_nonce_h * nonce);
 109 #if NOT_USED
 110 static int authDigestNonceLinks(digest_nonce_h * nonce);
 111 #endif
 112 static void authDigestNonceUserUnlink(digest_nonce_h * nonce);
 113
 114 static void
 115 authDigestNonceEncode(digest_nonce_h * nonce)
 116 {
 117     if (!nonce)
 118         return;
 119
 120     if (nonce->key)
 121         xfree(nonce->key);
 122
 123     nonce->key = xstrdup(base64_encode_bin((char *) &(nonce->noncedata), sizeof(digest_nonce_data)));
 124 }
 125
 126 static digest_nonce_h *
 127 authenticateDigestNonceNew(void)
 128 {
 129     digest_nonce_h *newnonce = static_cast < digest_nonce_h * >(digest_nonce_pool->alloc());
 130     digest_nonce_h *temp;
 131
 132     /* NONCE CREATION - NOTES AND REASONING. RBC 20010108
 133      * === EXCERPT FROM RFC 2617 ===
 134      * The contents of the nonce are implementation dependent. The quality
 135      * of the implementation depends on a good choice. A nonce might, for
 136      * example, be constructed as the base 64 encoding of
 137      *
 138      * time-stamp H(time-stamp ":" ETag ":" private-key)
 139      *
 140      * where time-stamp is a server-generated time or other non-repeating
 141      * value, ETag is the value of the HTTP ETag header associated with
 142      * the requested entity, and private-key is data known only to the
 143      * server.  With a nonce of this form a server would recalculate the
 144      * hash portion after receiving the client authentication header and
 145      * reject the request if it did not match the nonce from that header
 146      * or if the time-stamp value is not recent enough. In this way the
 147      * server can limit the time of the nonce's validity. The inclusion of
 148      * the ETag prevents a replay request for an updated version of the
 149      * resource.  (Note: including the IP address of the client in the
 150      * nonce would appear to offer the server the ability to limit the
 151      * reuse of the nonce to the same client that originally got it.
 152      * However, that would break proxy farms, where requests from a single
 153      * user often go through different proxies in the farm. Also, IP
 154      * address spoofing is not that hard.)
 155      * ====
 156      *
 157      * Now for my reasoning:
 158      * We will not accept a unrecognised nonce->we have all recognisable
 159      * nonces stored. If we send out unique base64 encodings we guarantee
 160      * that a given nonce applies to only one user (barring attacks or
 161      * really bad timing with expiry and creation).  Using a random
 162      * component in the nonce allows us to loop to find a unique nonce.
 163      * We use H(nonce_data) so the nonce is meaningless to the reciever.
 164      * So our nonce looks like base64(H(timestamp,pointertohash,randomdata))
 165      * And even if our randomness is not very random (probably due to
 166      * bad coding on my part) we don't really care - the timestamp and
 167      * memory pointer also guarantee local uniqueness in the input to the hash
 168      * function.
 169      */
 170
 171     /* create a new nonce */
 172     newnonce->nc = 0;
 173     newnonce->flags.valid = 1;
 174     newnonce->noncedata.self = newnonce;
 175     newnonce->noncedata.creationtime = current_time.tv_sec;
 176     newnonce->noncedata.randomdata = squid_random();
 177
 178     authDigestNonceEncode(newnonce);
 179     /*
 180      * loop until we get a unique nonce. The nonce creation must
 181      * have a random factor
 182      */
 183
 184     while ((temp = authenticateDigestNonceFindNonce((char const *) (newnonce->key)))) {
 185         /* create a new nonce */
 186         newnonce->noncedata.randomdata = squid_random();
 187         authDigestNonceEncode(newnonce);
 188     }
 189
 190     hash_join(digest_nonce_cache, newnonce);
 191     /* the cache's link */
 192     authDigestNonceLink(newnonce);
 193     newnonce->flags.incache = 1;
 194     debugs(29, 5, "authenticateDigestNonceNew: created nonce " << newnonce << " at " << newnonce->noncedata.creationtime);
 195     return newnonce;
 196 }
 197
 198 static void
 199 authenticateDigestNonceDelete(digest_nonce_h * nonce)
 200 {
 201     if (nonce) {
 202         assert(nonce->references == 0);
 203 #if UNREACHABLECODE
 204
 205         if (nonce->flags.incache)
 206             hash_remove_link(digest_nonce_cache, nonce);
 207
 208 #endif
 209
 210         assert(nonce->flags.incache == 0);
 211
 212         safe_free(nonce->key);
 213
 214         digest_nonce_pool->freeOne(nonce);
 215     }
 216 }
 217
 218 static void
 219 authenticateDigestNonceSetup(void)
 220 {
 221     if (!digest_nonce_pool)
 222         digest_nonce_pool = memPoolCreate("Digest Scheme nonce's", sizeof(digest_nonce_h));
 223
 224     if (!digest_nonce_cache) {
 225         digest_nonce_cache = hash_create((HASHCMP *) strcmp, 7921, hash_string);
 226         assert(digest_nonce_cache);
 227         eventAdd("Digest none cache maintenance", authenticateDigestNonceCacheCleanup, NULL, static_cast<Auth::Digest::Config*>(Auth::Config::Find("digest"))->nonceGCInterval, 1);
 228     }
 229 }
 230
 231 void
 232 authenticateDigestNonceShutdown(void)
 233 {
 234     /*
 235      * We empty the cache of any nonces left in there.
 236      */
 237     digest_nonce_h *nonce;
 238
 239     if (digest_nonce_cache) {
 240         debugs(29, 2, "authenticateDigestNonceShutdown: Shutting down nonce cache ");
 241         hash_first(digest_nonce_cache);
 242
 243         while ((nonce = ((digest_nonce_h *) hash_next(digest_nonce_cache)))) {
 244             assert(nonce->flags.incache);
 245             authDigestNoncePurge(nonce);
 246         }
 247     }
 248
 249 #if DEBUGSHUTDOWN
 250     if (digest_nonce_pool) {
 251         delete digest_nonce_pool;
 252         digest_nonce_pool = NULL;
 253     }
 254
 255 #endif
 256     debugs(29, 2, "authenticateDigestNonceShutdown: Nonce cache shutdown");
 257 }
 258
 259 static void
 260 authenticateDigestNonceCacheCleanup(void *data)
 261 {
 262     /*
 263      * We walk the hash by nonceb64 as that is the unique key we
 264      * use.  For big hash tables we could consider stepping through
 265      * the cache, 100/200 entries at a time. Lets see how it flies
 266      * first.
 267      */
 268     digest_nonce_h *nonce;
 269     debugs(29, 3, "authenticateDigestNonceCacheCleanup: Cleaning the nonce cache now");
 270     debugs(29, 3, "authenticateDigestNonceCacheCleanup: Current time: " << current_time.tv_sec);
 271     hash_first(digest_nonce_cache);
 272
 273     while ((nonce = ((digest_nonce_h *) hash_next(digest_nonce_cache)))) {
 274         debugs(29, 3, "authenticateDigestNonceCacheCleanup: nonce entry  : " << nonce << " '" << (char *) nonce->key << "'");
 275         debugs(29, 4, "authenticateDigestNonceCacheCleanup: Creation time: " << nonce->noncedata.creationtime);
 276
 277         if (authDigestNonceIsStale(nonce)) {
 278             debugs(29, 4, "authenticateDigestNonceCacheCleanup: Removing nonce " << (char *) nonce->key << " from cache due to timeout.");
 279             assert(nonce->flags.incache);
 280             /* invalidate nonce so future requests fail */
 281             nonce->flags.valid = 0;
 282             /* if it is tied to a auth_user, remove the tie */
 283             authDigestNonceUserUnlink(nonce);
 284             authDigestNoncePurge(nonce);
 285         }
 286     }
 287
 288     debugs(29, 3, "authenticateDigestNonceCacheCleanup: Finished cleaning the nonce cache.");
 289
 290     if (static_cast<Auth::Digest::Config*>(Auth::Config::Find("digest"))->active())
 291         eventAdd("Digest none cache maintenance", authenticateDigestNonceCacheCleanup, NULL, static_cast<Auth::Digest::Config*>(Auth::Config::Find("digest"))->nonceGCInterval, 1);
 292 }
 293
 294 static void
 295 authDigestNonceLink(digest_nonce_h * nonce)
 296 {
 297     assert(nonce != NULL);
 298     nonce->references++;
 299     debugs(29, 9, "authDigestNonceLink: nonce '" << nonce << "' now at '" << nonce->references << "'.");
 300 }
 301
 302 #if NOT_USED
 303 static int
 304 authDigestNonceLinks(digest_nonce_h * nonce)
 305 {
 306     if (!nonce)
 307         return -1;
 308
 309     return nonce->references;
 310 }
 311
 312 #endif
 313
 314 void
 315 authDigestNonceUnlink(digest_nonce_h * nonce)
 316 {
 317     assert(nonce != NULL);
 318
 319     if (nonce->references > 0) {
 320         nonce->references--;
 321     } else {
 322         debugs(29, 1, "authDigestNonceUnlink; Attempt to lower nonce " << nonce << " refcount below 0!");
 323     }
 324
 325     debugs(29, 9, "authDigestNonceUnlink: nonce '" << nonce << "' now at '" << nonce->references << "'.");
 326
 327     if (nonce->references == 0)
 328         authenticateDigestNonceDelete(nonce);
 329 }
 330
 331 const char *
 332 authenticateDigestNonceNonceb64(const digest_nonce_h * nonce)
 333 {
 334     if (!nonce)
 335         return NULL;
 336
 337     return (char const *) nonce->key;
 338 }
 339
 340 static digest_nonce_h *
 341 authenticateDigestNonceFindNonce(const char *nonceb64)
 342 {
 343     digest_nonce_h *nonce = NULL;
 344
 345     if (nonceb64 == NULL)
 346         return NULL;
 347
 348     debugs(29, 9, "authDigestNonceFindNonce:looking for nonceb64 '" << nonceb64 << "' in the nonce cache.");
 349
 350     nonce = static_cast < digest_nonce_h * >(hash_lookup(digest_nonce_cache, nonceb64));
 351
 352     if ((nonce == NULL) || (strcmp(authenticateDigestNonceNonceb64(nonce), nonceb64)))
 353         return NULL;
 354
 355     debugs(29, 9, "authDigestNonceFindNonce: Found nonce '" << nonce << "'");
 356
 357     return nonce;
 358 }
 359
 360 int
 361 authDigestNonceIsValid(digest_nonce_h * nonce, char nc[9])
 362 {
 363     unsigned long intnc;
 364     /* do we have a nonce ? */
 365
 366     if (!nonce)
 367         return 0;
 368
 369     intnc = strtol(nc, NULL, 16);
 370
 371     /* has it already been invalidated ? */
 372     if (!nonce->flags.valid) {
 373         debugs(29, 4, "authDigestNonceIsValid: Nonce already invalidated");
 374         return 0;
 375     }
 376
 377     /* is the nonce-count ok ? */
 378     if (!static_cast<Auth::Digest::Config*>(Auth::Config::Find("digest"))->CheckNonceCount) {
 379         nonce->nc++;
 380         return -1;              /* forced OK by configuration */
 381     }
 382
 383     if ((static_cast<Auth::Digest::Config*>(Auth::Config::Find("digest"))->NonceStrictness && intnc != nonce->nc + 1) ||
 384             intnc < nonce->nc + 1) {
 385         debugs(29, 4, "authDigestNonceIsValid: Nonce count doesn't match");
 386         nonce->flags.valid = 0;
 387         return 0;
 388     }
 389
 390     /* seems ok */
 391     /* increment the nonce count - we've already checked that intnc is a
 392      *  valid representation for us, so we don't need the test here.
 393      */
 394     nonce->nc = intnc;
 395
 396     return -1;
 397 }
 398
 399 static int
 400 authDigestNonceIsStale(digest_nonce_h * nonce)
 401 {
 402     /* do we have a nonce ? */
 403
 404     if (!nonce)
 405         return -1;
 406
 407     /* has it's max duration expired? */
 408     if (nonce->noncedata.creationtime + static_cast<Auth::Digest::Config*>(Auth::Config::Find("digest"))->noncemaxduration < current_time.tv_sec) {
 409         debugs(29, 4, "authDigestNonceIsStale: Nonce is too old. " <<
 410                nonce->noncedata.creationtime << " " <<
 411                static_cast<Auth::Digest::Config*>(Auth::Config::Find("digest"))->noncemaxduration << " " <<
 412                current_time.tv_sec);
 413
 414         nonce->flags.valid = 0;
 415         return -1;
 416     }
 417
 418     if (nonce->nc > 99999998) {
 419         debugs(29, 4, "authDigestNonceIsStale: Nonce count overflow");
 420         nonce->flags.valid = 0;
 421         return -1;
 422     }
 423
 424     if (nonce->nc > static_cast<Auth::Digest::Config*>(Auth::Config::Find("digest"))->noncemaxuses) {
 425         debugs(29, 4, "authDigestNoncelastRequest: Nonce count over user limit");
 426         nonce->flags.valid = 0;
 427         return -1;
 428     }
 429
 430     /* seems ok */
 431     return 0;
 432 }
 433
 434 /**
 435  * \retval  0    the digest is not stale yet
 436  * \retval -1    the digest will be stale on the next request
 437  */
 438 int
 439 authDigestNonceLastRequest(digest_nonce_h * nonce)
 440 {
 441     if (!nonce)
 442         return -1;
 443
 444     if (nonce->nc == 99999997) {
 445         debugs(29, 4, "authDigestNoncelastRequest: Nonce count about to overflow");
 446         return -1;
 447     }
 448
 449     if (nonce->nc >= static_cast<Auth::Digest::Config*>(Auth::Config::Find("digest"))->noncemaxuses - 1) {
 450         debugs(29, 4, "authDigestNoncelastRequest: Nonce count about to hit user limit");
 451         return -1;
 452     }
 453
 454     /* and other tests are possible. */
 455     return 0;
 456 }
 457
 458 void
 459 authDigestNoncePurge(digest_nonce_h * nonce)
 460 {
 461     if (!nonce)
 462         return;
 463
 464     if (!nonce->flags.incache)
 465         return;
 466
 467     hash_remove_link(digest_nonce_cache, nonce);
 468
 469     nonce->flags.incache = 0;
 470
 471     /* the cache's link */
 472     authDigestNonceUnlink(nonce);
 473 }
 474
 475 /* USER related functions */
 476 static Auth::User::Pointer
 477 authDigestUserFindUsername(const char *username)
 478 {
 479     AuthUserHashPointer *usernamehash;
 480     debugs(29, 9, HERE << "Looking for user '" << username << "'");
 481
 482     if (username && (usernamehash = static_cast < AuthUserHashPointer * >(hash_lookup(proxy_auth_username_cache, username)))) {
 483         while ((usernamehash->user()->auth_type != Auth::AUTH_DIGEST) && (usernamehash->next))
 484             usernamehash = static_cast<AuthUserHashPointer *>(usernamehash->next);
 485
 486         if (usernamehash->user()->auth_type == Auth::AUTH_DIGEST) {
 487             return usernamehash->user();
 488         }
 489     }
 490
 491     return NULL;
 492 }
 493
 494 void
 495 Auth::Digest::Config::rotateHelpers()
 496 {
 497     /* schedule closure of existing helpers */
 498     if (digestauthenticators) {
 499         helperShutdown(digestauthenticators);
 500     }
 501
 502     /* NP: dynamic helper restart will ensure they start up again as needed. */
 503 }
 504
 505 void
 506 Auth::Digest::Config::dump(StoreEntry * entry, const char *name, Auth::Config * scheme)
 507 {
 508     wordlist *list = authenticateProgram;
 509     debugs(29, 9, "authDigestCfgDump: Dumping configuration");
 510     storeAppendPrintf(entry, "%s %s", name, "digest");
 511
 512     while (list != NULL) {
 513         storeAppendPrintf(entry, " %s", list->key);
 514         list = list->next;
 515     }
 516
 517     storeAppendPrintf(entry, "\n%s %s realm %s\n%s %s children %d startup=%d idle=%d concurrency=%d\n%s %s nonce_max_count %d\n%s %s nonce_max_duration %d seconds\n%s %s nonce_garbage_interval %d seconds\n",
 518                       name, "digest", digestAuthRealm,
 519                       name, "digest", authenticateChildren.n_max, authenticateChildren.n_startup, authenticateChildren.n_idle, authenticateChildren.concurrency,
 520                       name, "digest", noncemaxuses,
 521                       name, "digest", (int) noncemaxduration,
 522                       name, "digest", (int) nonceGCInterval);
 523 }
 524
 525 bool
 526 Auth::Digest::Config::active() const
 527 {
 528     return authdigest_initialised == 1;
 529 }
 530
 531 bool
 532 Auth::Digest::Config::configured() const
 533 {
 534     if ((authenticateProgram != NULL) &&
 535             (authenticateChildren.n_max != 0) &&
 536             (digestAuthRealm != NULL) && (noncemaxduration > -1))
 537         return true;
 538
 539     return false;
 540 }
 541
 542 /* add the [www-|Proxy-]authenticate header on a 407 or 401 reply */
 543 void
 544 Auth::Digest::Config::fixHeader(AuthUserRequest::Pointer auth_user_request, HttpReply *rep, http_hdr_type hdrType, HttpRequest * request)
 545 {
 546     if (!authenticateProgram)
 547         return;
 548
 549     int stale = 0;
 550
 551     if (auth_user_request != NULL) {
 552         AuthDigestUserRequest *digest_request;
 553         digest_request = dynamic_cast<AuthDigestUserRequest*>(auth_user_request.getRaw());
 554         assert (digest_request != NULL);
 555
 556         stale = !digest_request->flags.invalid_password;
 557     }
 558
 559     /* on a 407 or 401 we always use a new nonce */
 560     digest_nonce_h *nonce = authenticateDigestNonceNew();
 561
 562     debugs(29, 9, "authenticateFixHeader: Sending type:" << hdrType <<
 563            " header: 'Digest realm=\"" << digestAuthRealm << "\", nonce=\"" <<
 564            authenticateDigestNonceNonceb64(nonce) << "\", qop=\"" << QOP_AUTH <<
 565            "\", stale=" << (stale ? "true" : "false"));
 566
 567     /* in the future, for WWW auth we may want to support the domain entry */
 568     httpHeaderPutStrf(&rep->header, hdrType, "Digest realm=\"%s\", nonce=\"%s\", qop=\"%s\", stale=%s", digestAuthRealm, authenticateDigestNonceNonceb64(nonce), QOP_AUTH, stale ? "true" : "false");
 569 }
 570
 571 /* Initialize helpers and the like for this auth scheme. Called AFTER parsing the
 572  * config file */
 573 void
 574 Auth::Digest::Config::init(Auth::Config * scheme)
 575 {
 576     if (authenticateProgram) {
 577         DigestFieldsInfo = httpHeaderBuildFieldsInfo(DigestAttrs, DIGEST_ENUM_END);
 578         authenticateDigestNonceSetup();
 579         authdigest_initialised = 1;
 580
 581         if (digestauthenticators == NULL)
 582             digestauthenticators = new helper("digestauthenticator");
 583
 584         digestauthenticators->cmdline = authenticateProgram;
 585
 586         digestauthenticators->childs = authenticateChildren;
 587
 588         digestauthenticators->ipc_type = IPC_STREAM;
 589
 590         helperOpenServers(digestauthenticators);
 591     }
 592 }
 593
 594 void
 595 Auth::Digest::Config::registerWithCacheManager(void)
 596 {
 597     Mgr::RegisterAction("digestauthenticator",
 598                         "Digest User Authenticator Stats",
 599                         authenticateDigestStats, 0, 1);
 600 }
 601
 602 /* free any allocated configuration details */
 603 void
 604 Auth::Digest::Config::done()
 605 {
 606     authdigest_initialised = 0;
 607
 608     if (digestauthenticators)
 609         helperShutdown(digestauthenticators);
 610
 611     if (DigestFieldsInfo) {
 612         httpHeaderDestroyFieldsInfo(DigestFieldsInfo, DIGEST_ENUM_END);
 613         DigestFieldsInfo = NULL;
 614     }
 615
 616     if (!shutting_down)
 617         return;
 618
 619     delete digestauthenticators;
 620     digestauthenticators = NULL;
 621
 622     if (authenticateProgram)
 623         wordlistDestroy(&authenticateProgram);
 624
 625     safe_free(digestAuthRealm);
 626 }
 627
 628 Auth::Digest::Config::Config() :
 629         digestAuthRealm(NULL),
 630         nonceGCInterval(5*60),
 631         noncemaxduration(30*60),
 632         noncemaxuses(50),
 633         NonceStrictness(0),
 634         CheckNonceCount(1),
 635         PostWorkaround(0),
 636         utf8(0)
 637 {}
 638
 639 void
 640 Auth::Digest::Config::parse(Auth::Config * scheme, int n_configured, char *param_str)
 641 {
 642     if (strcasecmp(param_str, "program") == 0) {
 643         if (authenticateProgram)
 644             wordlistDestroy(&authenticateProgram);
 645
 646         parse_wordlist(&authenticateProgram);
 647
 648         requirePathnameExists("auth_param digest program", authenticateProgram->key);
 649     } else if (strcasecmp(param_str, "children") == 0) {
 650         authenticateChildren.parseConfig();
 651     } else if (strcasecmp(param_str, "realm") == 0) {
 652         parse_eol(&digestAuthRealm);
 653     } else if (strcasecmp(param_str, "nonce_garbage_interval") == 0) {
 654         parse_time_t(&nonceGCInterval);
 655     } else if (strcasecmp(param_str, "nonce_max_duration") == 0) {
 656         parse_time_t(&noncemaxduration);
 657     } else if (strcasecmp(param_str, "nonce_max_count") == 0) {
 658         parse_int((int *) &noncemaxuses);
 659     } else if (strcasecmp(param_str, "nonce_strictness") == 0) {
 660         parse_onoff(&NonceStrictness);
 661     } else if (strcasecmp(param_str, "check_nonce_count") == 0) {
 662         parse_onoff(&CheckNonceCount);
 663     } else if (strcasecmp(param_str, "post_workaround") == 0) {
 664         parse_onoff(&PostWorkaround);
 665     } else if (strcasecmp(param_str, "utf8") == 0) {
 666         parse_onoff(&utf8);
 667     } else {
 668         debugs(29, 0, "unrecognised digest auth scheme parameter '" << param_str << "'");
 669     }
 670 }
 671
 672 const char *
 673 Auth::Digest::Config::type() const
 674 {
 675     return Auth::Digest::Scheme::GetInstance()->type();
 676 }
 677
 678
 679 static void
 680 authenticateDigestStats(StoreEntry * sentry)
 681 {
 682     helperStats(sentry, digestauthenticators, "Digest Authenticator Statistics");
 683 }
 684
 685 /* NonceUserUnlink: remove the reference to auth_user and unlink the node from the list */
 686
 687 static void
 688 authDigestNonceUserUnlink(digest_nonce_h * nonce)
 689 {
 690     Auth::Digest::User *digest_user;
 691     dlink_node *link, *tmplink;
 692
 693     if (!nonce)
 694         return;
 695
 696     if (!nonce->user)
 697         return;
 698
 699     digest_user = nonce->user;
 700
 701     /* unlink from the user list. Yes we're crossing structures but this is the only
 702      * time this code is needed
 703      */
 704     link = digest_user->nonces.head;
 705
 706     while (link) {
 707         tmplink = link;
 708         link = link->next;
 709
 710         if (tmplink->data == nonce) {
 711             dlinkDelete(tmplink, &digest_user->nonces);
 712             authDigestNonceUnlink(static_cast < digest_nonce_h * >(tmplink->data));
 713             dlinkNodeDelete(tmplink);
 714             link = NULL;
 715         }
 716     }
 717
 718     /* this reference to user was not locked because freeeing the user frees
 719      * the nonce too.
 720      */
 721     nonce->user = NULL;
 722 }
 723
 724 /* authDigestUserLinkNonce: add a nonce to a given user's struct */
 725 static void
 726 authDigestUserLinkNonce(Auth::Digest::User * user, digest_nonce_h * nonce)
 727 {
 728     dlink_node *node;
 729
 730     if (!user || !nonce)
 731         return;
 732
 733     Auth::Digest::User *digest_user = user;
 734
 735     node = digest_user->nonces.head;
 736
 737     while (node && (node->data != nonce))
 738         node = node->next;
 739
 740     if (node)
 741         return;
 742
 743     node = dlinkNodeNew();
 744
 745     dlinkAddTail(nonce, node, &digest_user->nonces);
 746
 747     authDigestNonceLink(nonce);
 748
 749     /* ping this nonce to this auth user */
 750     assert((nonce->user == NULL) || (nonce->user == user));
 751
 752     /* we don't lock this reference because removing the user removes the
 753      * hash too. Of course if that changes we're stuffed so read the code huh?
 754      */
 755     nonce->user = user;
 756 }
 757
 758 /* setup the necessary info to log the username */
 759 static AuthUserRequest::Pointer
 760 authDigestLogUsername(char *username, AuthUserRequest::Pointer auth_user_request)
 761 {
 762     assert(auth_user_request != NULL);
 763
 764     /* log the username */
 765     debugs(29, 9, "authDigestLogUsername: Creating new user for logging '" << username << "'");
 766     Auth::User::Pointer digest_user = new Auth::Digest::User(static_cast<Auth::Digest::Config*>(Auth::Config::Find("digest")));
 767     /* save the credentials */
 768     digest_user->username(username);
 769     /* set the auth_user type */
 770     digest_user->auth_type = Auth::AUTH_BROKEN;
 771     /* link the request to the user */
 772     auth_user_request->user(digest_user);
 773     return auth_user_request;
 774 }
 775
 776 /*
 777  * Decode a Digest [Proxy-]Auth string, placing the results in the passed
 778  * Auth_user structure.
 779  */
 780 AuthUserRequest::Pointer
 781 Auth::Digest::Config::decode(char const *proxy_auth)
 782 {
 783     const char *item;
 784     const char *p;
 785     const char *pos = NULL;
 786     char *username = NULL;
 787     digest_nonce_h *nonce;
 788     int ilen;
 789
 790     debugs(29, 9, "authenticateDigestDecodeAuth: beginning");
 791
 792     AuthDigestUserRequest *digest_request = new AuthDigestUserRequest();
 793
 794     /* trim DIGEST from string */
 795
 796     while (xisgraph(*proxy_auth))
 797         proxy_auth++;
 798
 799     /* Trim leading whitespace before decoding */
 800     while (xisspace(*proxy_auth))
 801         proxy_auth++;
 802
 803     String temp(proxy_auth);
 804
 805     while (strListGetItem(&temp, ',', &item, &ilen, &pos)) {
 806         /* isolate directive name & value */
 807         size_t nlen;
 808         size_t vlen;
 809         if ((p = (const char *)memchr(item, '=', ilen)) && (p - item < ilen)) {
 810             nlen = p++ - item;
 811             vlen = ilen - (p - item);
 812         } else {
 813             nlen = ilen;
 814             vlen = 0;
 815         }
 816
 817         /* parse value. auth-param     = token "=" ( token | quoted-string ) */
 818         String value;
 819         if (vlen > 0) {
 820             if (*p == '"') {
 821                 if (!httpHeaderParseQuotedString(p, vlen, &value)) {
 822                     debugs(29, 9, "authDigestDecodeAuth: Failed to parse attribute '" << item << "' in '" << temp << "'");
 823                     continue;
 824                 }
 825             } else {
 826                 value.limitInit(p, vlen);
 827             }
 828         } else {
 829             debugs(29, 9, "authDigestDecodeAuth: Failed to parse attribute '" << item << "' in '" << temp << "'");
 830             continue;
 831         }
 832
 833         /* find type */
 834         http_digest_attr_type type = (http_digest_attr_type)httpHeaderIdByName(item, nlen, DigestFieldsInfo, DIGEST_ENUM_END);
 835
 836         switch (type) {
 837         case DIGEST_USERNAME:
 838             safe_free(username);
 839             username = xstrndup(value.rawBuf(), value.size() + 1);
 840             debugs(29, 9, "authDigestDecodeAuth: Found Username '" << username << "'");
 841             break;
 842
 843         case DIGEST_REALM:
 844             safe_free(digest_request->realm);
 845             digest_request->realm = xstrndup(value.rawBuf(), value.size() + 1);
 846             debugs(29, 9, "authDigestDecodeAuth: Found realm '" << digest_request->realm << "'");
 847             break;
 848
 849         case DIGEST_QOP:
 850             safe_free(digest_request->qop);
 851             digest_request->qop = xstrndup(value.rawBuf(), value.size() + 1);
 852             debugs(29, 9, "authDigestDecodeAuth: Found qop '" << digest_request->qop << "'");
 853             break;
 854
 855         case DIGEST_ALGORITHM:
 856             safe_free(digest_request->algorithm);
 857             digest_request->algorithm = xstrndup(value.rawBuf(), value.size() + 1);
 858             debugs(29, 9, "authDigestDecodeAuth: Found algorithm '" << digest_request->algorithm << "'");
 859             break;
 860
 861         case DIGEST_URI:
 862             safe_free(digest_request->uri);
 863             digest_request->uri = xstrndup(value.rawBuf(), value.size() + 1);
 864             debugs(29, 9, "authDigestDecodeAuth: Found uri '" << digest_request->uri << "'");
 865             break;
 866
 867         case DIGEST_NONCE:
 868             safe_free(digest_request->nonceb64);
 869             digest_request->nonceb64 = xstrndup(value.rawBuf(), value.size() + 1);
 870             debugs(29, 9, "authDigestDecodeAuth: Found nonce '" << digest_request->nonceb64 << "'");
 871             break;
 872
 873         case DIGEST_NC:
 874             if (value.size() != 8) {
 875                 debugs(29, 9, "authDigestDecodeAuth: Invalid nc '" << value << "' in '" << temp << "'");
 876             }
 877             xstrncpy(digest_request->nc, value.rawBuf(), value.size() + 1);
 878             debugs(29, 9, "authDigestDecodeAuth: Found noncecount '" << digest_request->nc << "'");
 879             break;
 880
 881         case DIGEST_CNONCE:
 882             safe_free(digest_request->cnonce);
 883             digest_request->cnonce = xstrndup(value.rawBuf(), value.size() + 1);
 884             debugs(29, 9, "authDigestDecodeAuth: Found cnonce '" << digest_request->cnonce << "'");
 885             break;
 886
 887         case DIGEST_RESPONSE:
 888             safe_free(digest_request->response);
 889             digest_request->response = xstrndup(value.rawBuf(), value.size() + 1);
 890             debugs(29, 9, "authDigestDecodeAuth: Found response '" << digest_request->response << "'");
 891             break;
 892
 893         default:
 894             debugs(29, 3, "authDigestDecodeAuth: Unknown attribute '" << item << "' in '" << temp << "'");
 895             break;
 896         }
 897     }
 898
 899     temp.clean();
 900
 901
 902     /* now we validate the data given to us */
 903
 904     /*
 905      * TODO: on invalid parameters we should return 400, not 407.
 906      * Find some clean way of doing this. perhaps return a valid
 907      * struct, and set the direction to clientwards combined with
 908      * a change to the clientwards handling code (ie let the
 909      * clientwards call set the error type (but limited to known
 910      * correct values - 400/401/407
 911      */
 912
 913     /* 2069 requirements */
 914
 915     /* do we have a username ? */
 916     if (!username || username[0] == '\0') {
 917         debugs(29, 2, "authenticateDigestDecode: Empty or not present username");
 918         return authDigestLogUsername(username, digest_request);
 919     }
 920
 921     /* Sanity check of the username.
 922      * " can not be allowed in usernames until * the digest helper protocol
 923      * have been redone
 924      */
 925     if (strchr(username, '"')) {
 926         debugs(29, 2, "authenticateDigestDecode: Unacceptable username '" << username << "'");
 927         return authDigestLogUsername(username, digest_request);
 928     }
 929
 930     /* do we have a realm ? */
 931     if (!digest_request->realm || digest_request->realm[0] == '\0') {
 932         debugs(29, 2, "authenticateDigestDecode: Empty or not present realm");
 933         return authDigestLogUsername(username, digest_request);
 934     }
 935
 936     /* and a nonce? */
 937     if (!digest_request->nonceb64 || digest_request->nonceb64[0] == '\0') {
 938         debugs(29, 2, "authenticateDigestDecode: Empty or not present nonce");
 939         return authDigestLogUsername(username, digest_request);
 940     }
 941
 942     /* we can't check the URI just yet. We'll check it in the
 943      * authenticate phase, but needs to be given */
 944     if (!digest_request->uri || digest_request->uri[0] == '\0') {
 945         debugs(29, 2, "authenticateDigestDecode: Missing URI field");
 946         return authDigestLogUsername(username, digest_request);
 947     }
 948
 949     /* is the response the correct length? */
 950     if (!digest_request->response || strlen(digest_request->response) != 32) {
 951         debugs(29, 2, "authenticateDigestDecode: Response length invalid");
 952         return authDigestLogUsername(username, digest_request);
 953     }
 954
 955     /* check the algorithm is present and supported */
 956     if (!digest_request->algorithm)
 957         digest_request->algorithm = xstrndup("MD5", 4);
 958     else if (strcmp(digest_request->algorithm, "MD5")
 959              && strcmp(digest_request->algorithm, "MD5-sess")) {
 960         debugs(29, 2, "authenticateDigestDecode: invalid algorithm specified!");
 961         return authDigestLogUsername(username, digest_request);
 962     }
 963
 964     /* 2617 requirements, indicated by qop */
 965     if (digest_request->qop) {
 966
 967         /* check the qop is what we expected. */
 968         if (strcmp(digest_request->qop, QOP_AUTH) != 0) {
 969             /* we received a qop option we didn't send */
 970             debugs(29, 2, "authenticateDigestDecode: Invalid qop option received");
 971             return authDigestLogUsername(username, digest_request);
 972         }
 973
 974         /* check cnonce */
 975         if (!digest_request->cnonce || digest_request->cnonce[0] == '\0') {
 976             debugs(29, 2, "authenticateDigestDecode: Missing cnonce field");
 977             return authDigestLogUsername(username, digest_request);
 978         }
 979
 980         /* check nc */
 981         if (strlen(digest_request->nc) != 8 || strspn(digest_request->nc, "0123456789abcdefABCDEF") != 8) {
 982             debugs(29, 2, "authenticateDigestDecode: invalid nonce count");
 983             return authDigestLogUsername(username, digest_request);
 984         }
 985     } else {
 986         /* cnonce and nc both require qop */
 987         if (digest_request->cnonce || digest_request->nc) {
 988             debugs(29, 2, "authenticateDigestDecode: missing qop!");
 989             return authDigestLogUsername(username, digest_request);
 990         }
 991     }
 992
 993     /** below nonce state dependent **/
 994
 995     /* now the nonce */
 996     nonce = authenticateDigestNonceFindNonce(digest_request->nonceb64);
 997     if (!nonce) {
 998         /* we couldn't find a matching nonce! */
 999         debugs(29, 2, "authenticateDigestDecode: Unexpected or invalid nonce received");
1000         if (digest_request->user() != NULL)
1001             digest_request->user()->credentials(Auth::Failed);
1002         return authDigestLogUsername(username, digest_request);
1003     }
1004
1005     digest_request->nonce = nonce;
1006     authDigestNonceLink(nonce);
1007
1008     /* check that we're not being hacked / the username hasn't changed */
1009     if (nonce->user && strcmp(username, nonce->user->username())) {
1010         debugs(29, 2, "authenticateDigestDecode: Username for the nonce does not equal the username for the request");
1011         return authDigestLogUsername(username, digest_request);
1012     }
1013
1014     /* the method we'll check at the authenticate step as well */
1015
1016
1017     /* we don't send or parse opaques. Ok so we're flexable ... */
1018
1019     /* find the user */
1020     Auth::Digest::User *digest_user;
1021
1022     Auth::User::Pointer auth_user;
1023
1024     if ((auth_user = authDigestUserFindUsername(username)) == NULL) {
1025         /* the user doesn't exist in the username cache yet */
1026         debugs(29, 9, "authDigestDecodeAuth: Creating new digest user '" << username << "'");
1027         digest_user = new Auth::Digest::User(this);
1028         /* auth_user is a parent */
1029         auth_user = digest_user;
1030         /* save the username */
1031         digest_user->username(username);
1032         /* set the user type */
1033         digest_user->auth_type = Auth::AUTH_DIGEST;
1034         /* this auth_user struct is the one to get added to the
1035          * username cache */
1036         /* store user in hash's */
1037         digest_user->addToNameCache();
1038
1039         /*
1040          * Add the digest to the user so we can tell if a hacking
1041          * or spoofing attack is taking place. We do this by assuming
1042          * the user agent won't change user name without warning.
1043          */
1044         authDigestUserLinkNonce(digest_user, nonce);
1045     } else {
1046         debugs(29, 9, "authDigestDecodeAuth: Found user '" << username << "' in the user cache as '" << auth_user << "'");
1047         digest_user = static_cast<Auth::Digest::User *>(auth_user.getRaw());
1048         xfree(username);
1049     }
1050
1051     /*link the request and the user */
1052     assert(digest_request != NULL);
1053
1054     digest_request->user(digest_user);
1055     debugs(29, 9, "username = '" << digest_user->username() << "'\nrealm = '" <<
1056            digest_request->realm << "'\nqop = '" << digest_request->qop <<
1057            "'\nalgorithm = '" << digest_request->algorithm << "'\nuri = '" <<
1058            digest_request->uri << "'\nnonce = '" << digest_request->nonceb64 <<
1059            "'\nnc = '" << digest_request->nc << "'\ncnonce = '" <<
1060            digest_request->cnonce << "'\nresponse = '" <<
1061            digest_request->response << "'\ndigestnonce = '" << nonce << "'");
1062
1063     return digest_request;
1064 }