cups/auth.c

   1 /*
   2  * "$Id: auth.c 6673 2007-07-14 00:16:39Z mike $"
   3  *
   4  *   Authentication functions for the Common UNIX Printing System (CUPS).
   5  *
   6  *   Copyright 2007 by Apple Inc.
   7  *   Copyright 1997-2007 by Easy Software Products.
   8  *
   9  *   This file contains Kerberos support code, copyright 2006 by
  10  *   Jelmer Vernooij.
  11  *
  12  *   These coded instructions, statements, and computer programs are the
  13  *   property of Apple Inc. and are protected by Federal copyright
  14  *   law.  Distribution and use rights are outlined in the file "LICENSE.txt"
  15  *   which should have been included with this file.  If this file is
  16  *   file is missing or damaged, see the license at "http://www.cups.org/".
  17  *
  18  *   This file is subject to the Apple OS-Developed Software exception.
  19  *
  20  * Contents:
  21  *
  22  *   cupsDoAuthentication() - Authenticate a request.
  23  *   DEBUG_gss_printf()     - Show debug error messages from GSSAPI...
  24  *   cups_get_gss_creds()   - Get CUPS service credentials for authentication.
  25  *   cups_local_auth()      - Get the local authorization certificate if
  26  *                            available/applicable...
  27  */
  28
  29 /*
  30  * Include necessary headers...
  31  */
  32
  33 #include "globals.h"
  34 #include "debug.h"
  35 #include <stdlib.h>
  36 #include <ctype.h>
  37 #include <errno.h>
  38 #include <fcntl.h>
  39 #include <sys/stat.h>
  40 #if defined(WIN32) || defined(__EMX__)
  41 #  include <io.h>
  42 #else
  43 #  include <unistd.h>
  44 #endif /* WIN32 || __EMX__ */
  45
  46 #if HAVE_AUTHORIZATION_H
  47 #  include <Security/Authorization.h>
  48 #  ifdef HAVE_SECBASEPRIV_H
  49 #    include <Security/SecBasePriv.h>
  50 #  else
  51 extern const char *cssmErrorString(int error);
  52 #  endif /* HAVE_SECBASEPRIV_H */
  53 #endif /* HAVE_AUTHORIZATION_H */
  54
  55 #if defined(SO_PEERCRED) && defined(AF_LOCAL)
  56 #  include <pwd.h>
  57 #endif /* SO_PEERCRED && AF_LOCAL */
  58
  59
  60 /*
  61  * Local functions...
  62  */
  63
  64 #ifdef HAVE_GSSAPI
  65 #  ifdef DEBUG
  66 static void     DEBUG_gss_printf(OM_uint32 major_status, OM_uint32 minor_status,
  67                                  const char *message);
  68 #  endif /* DEBUG  */
  69 static gss_name_t cups_get_gss_creds(http_t *http, const char *service_name);
  70 #endif /* HAVE_GSSAPI */
  71 static int      cups_local_auth(http_t *http);
  72
  73
  74 /*
  75  * 'cupsDoAuthentication()' - Authenticate a request.
  76  *
  77  * This function should be called in response to a HTTP_UNAUTHORIZED
  78  * status, prior to resubmitting your request.
  79  *
  80  * @since CUPS 1.1.20@
  81  */
  82
  83 int                                     /* O - 0 on success, -1 on error */
  84 cupsDoAuthentication(http_t     *http,  /* I - HTTP connection to server */
  85                      const char *method,/* I - Request method (GET, POST, PUT) */
  86                      const char *resource)
  87                                         /* I - Resource path */
  88 {
  89   const char    *password;              /* Password string */
  90   char          prompt[1024],           /* Prompt for user */
  91                 realm[HTTP_MAX_VALUE],  /* realm="xyz" string */
  92                 nonce[HTTP_MAX_VALUE],  /* nonce="xyz" string */
  93                 encode[2048];           /* Encoded username:password */
  94   int           localauth;              /* Local authentication result */
  95   _cups_globals_t *cg;                  /* Global data */
  96
  97
  98   DEBUG_printf(("cupsDoAuthentication(http=%p, method=\"%s\", resource=\"%s\")\n",
  99                 http, method, resource));
 100   DEBUG_printf(("cupsDoAuthentication: digest_tries=%d, userpass=\"%s\"\n",
 101                 http->digest_tries, http->userpass));
 102   DEBUG_printf(("cupsDoAuthentication: WWW-Authenticate=\"%s\"\n",
 103                 httpGetField(http, HTTP_FIELD_WWW_AUTHENTICATE)));
 104
 105  /*
 106   * Clear the current authentication string...
 107   */
 108
 109   http->_authstring[0] = '\0';
 110
 111   if (http->authstring && http->authstring != http->_authstring)
 112     free(http->authstring);
 113
 114   http->authstring = http->_authstring;
 115
 116  /*
 117   * See if we can do local authentication...
 118   */
 119
 120   if (http->digest_tries < 3)
 121   {
 122     if ((localauth = cups_local_auth(http)) == 0)
 123     {
 124       DEBUG_printf(("cupsDoAuthentication: authstring=\"%s\"\n",
 125                     http->authstring));
 126
 127       if (http->status == HTTP_UNAUTHORIZED)
 128         http->digest_tries ++;
 129
 130       return (0);
 131     }
 132     else if (localauth == -1)
 133       return (-1);                      /* Error or canceled */
 134   }
 135
 136  /*
 137   * Nope, see if we should retry the current username:password...
 138   */
 139
 140   if ((http->digest_tries > 1 || !http->userpass[0]) &&
 141       strncmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE], "Negotiate", 9))
 142   {
 143    /*
 144     * Nope - get a new password from the user...
 145     */
 146
 147     cg = _cupsGlobals();
 148
 149     if (!cg->lang_default)
 150       cg->lang_default = cupsLangDefault();
 151
 152     snprintf(prompt, sizeof(prompt),
 153              _cupsLangString(cg->lang_default, _("Password for %s on %s? ")),
 154              cupsUser(),
 155              http->hostname[0] == '/' ? "localhost" : http->hostname);
 156
 157     http->digest_tries  = strncasecmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE],
 158                                       "Digest", 5) != 0;
 159     http->userpass[0]   = '\0';
 160
 161     if ((password = cupsGetPassword(prompt)) == NULL)
 162       return (-1);
 163
 164     if (!password[0])
 165       return (-1);
 166
 167     snprintf(http->userpass, sizeof(http->userpass), "%s:%s", cupsUser(),
 168              password);
 169   }
 170   else if (http->status == HTTP_UNAUTHORIZED)
 171     http->digest_tries ++;
 172
 173  /*
 174   * Got a password; encode it for the server...
 175   */
 176
 177   if (!strncmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE], "Negotiate", 9))
 178   {
 179     if (http->status == HTTP_UNAUTHORIZED && http->digest_tries >= 3)
 180     {
 181       DEBUG_printf(("cupsDoAuthentication: too many Negotiate tries (%d)\n",
 182                     http->digest_tries));
 183
 184       return (-1);
 185     }
 186 #ifdef HAVE_GSSAPI
 187    /*
 188     * Kerberos authentication...
 189     */
 190
 191     OM_uint32           minor_status,   /* Minor status code */
 192                         major_status;   /* Major status code */
 193     gss_buffer_desc     output_token = GSS_C_EMPTY_BUFFER,
 194                                         /* Output token */
 195                         input_token = GSS_C_EMPTY_BUFFER;
 196                                         /* Input token */
 197     char                *gss_service_name;
 198                                         /* GSS service name */
 199     const char          *authorization;
 200                                         /* Pointer into Authorization string */
 201
 202
 203 #  ifdef __APPLE__
 204    /*
 205     * If the weak-linked GSSAPI/Kerberos library is not present, don't try
 206     * to use it...
 207     */
 208
 209     if (gss_init_sec_context == NULL)
 210     {
 211       DEBUG_puts("cupsDoAuthentication: Weak-linked GSSAPI/Kerberos framework "
 212                  "is not present");
 213       return (-1);
 214     }
 215 #  endif /* __APPLE__ */
 216
 217     if (http->gssname == GSS_C_NO_NAME)
 218     {
 219       if ((gss_service_name = getenv("CUPS_GSSSERVICENAME")) == NULL)
 220         gss_service_name = CUPS_DEFAULT_GSSSERVICENAME;
 221       else
 222         DEBUG_puts("cupsDoAuthentication: GSS service name set via environment");
 223
 224       http->gssname = cups_get_gss_creds(http, gss_service_name);
 225     }
 226
 227    /*
 228     * Find the start of the Kerberos input token...
 229     */
 230
 231     authorization = httpGetField(http, HTTP_FIELD_WWW_AUTHENTICATE);
 232
 233     authorization += 9;
 234     while (*authorization && isspace(*authorization & 255))
 235       authorization ++;
 236
 237     if (*authorization)
 238     {
 239      /*
 240       * For SPNEGO, this is where we'll feed the server's authorization data
 241       * back into gss via input_token...
 242       */
 243     }
 244
 245     if (http->gssctx != GSS_C_NO_CONTEXT)
 246     {
 247       major_status = gss_delete_sec_context(&minor_status, &http->gssctx,
 248                                             GSS_C_NO_BUFFER);
 249       http->gssctx = GSS_C_NO_CONTEXT;
 250     }
 251
 252     major_status  = gss_init_sec_context(&minor_status, GSS_C_NO_CREDENTIAL,
 253                                          &http->gssctx,
 254                                          http->gssname, http->gssmech,
 255                                          GSS_C_DELEG_FLAG | GSS_C_MUTUAL_FLAG,
 256                                          GSS_C_INDEFINITE,
 257                                          GSS_C_NO_CHANNEL_BINDINGS,
 258                                          &input_token, &http->gssmech,
 259                                          &output_token, NULL, NULL);
 260
 261     if (input_token.value)
 262       free(input_token.value);
 263
 264     if (GSS_ERROR(major_status))
 265     {
 266 #  ifdef DEBUG
 267       DEBUG_gss_printf(major_status, minor_status,
 268                        "Unable to initialise security context");
 269 #  endif /* DEBUG */
 270       return (-1);
 271     }
 272
 273 #  ifdef DEBUG
 274     if (major_status == GSS_S_CONTINUE_NEEDED)
 275       DEBUG_gss_printf(major_status, minor_status, "Continuation needed!");
 276 #  endif /* DEBUG */
 277
 278     if (output_token.length)
 279     {
 280       httpEncode64_2(encode, sizeof(encode), output_token.value,
 281                      output_token.length);
 282
 283       http->authstring = malloc(strlen(encode) + 11);
 284       sprintf(http->authstring, "Negotiate %s", encode); /* Safe because allocated */
 285
 286       major_status = gss_release_buffer(&minor_status, &output_token);
 287     }
 288
 289    /*
 290     * Copy back what we can to _authstring for backwards compatibility...
 291     */
 292
 293     strlcpy(http->_authstring, http->authstring, sizeof(http->_authstring));
 294 #endif /* HAVE_GSSAPI */
 295   }
 296   else if (strncmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE], "Digest", 6))
 297   {
 298    /*
 299     * Basic authentication...
 300     */
 301
 302     httpEncode64_2(encode, sizeof(encode), http->userpass,
 303                    (int)strlen(http->userpass));
 304     snprintf(http->_authstring, sizeof(http->_authstring), "Basic %s", encode);
 305   }
 306   else
 307   {
 308    /*
 309     * Digest authentication...
 310     */
 311
 312     httpGetSubField(http, HTTP_FIELD_WWW_AUTHENTICATE, "realm", realm);
 313     httpGetSubField(http, HTTP_FIELD_WWW_AUTHENTICATE, "nonce", nonce);
 314
 315     httpMD5(cupsUser(), realm, strchr(http->userpass, ':') + 1, encode);
 316     httpMD5Final(nonce, method, resource, encode);
 317     snprintf(http->_authstring, sizeof(http->_authstring),
 318              "Digest username=\"%s\", realm=\"%s\", nonce=\"%s\", "
 319              "uri=\"%s\", response=\"%s\"", cupsUser(), realm, nonce,
 320              resource, encode);
 321   }
 322
 323   DEBUG_printf(("cupsDoAuthentication: authstring=\"%s\"\n", http->authstring));
 324
 325   return (0);
 326 }
 327
 328
 329 #ifdef HAVE_GSSAPI
 330 #  ifdef DEBUG
 331 /*
 332  * 'DEBUG_gss_printf()' - Show debug error messages from GSSAPI...
 333  */
 334
 335 static void
 336 DEBUG_gss_printf(OM_uint32 major_status,/* I - Major status code */
 337                  OM_uint32 minor_status,/* I - Minor status code */
 338                  const char *message)   /* I - Prefix for error message */
 339 {
 340   OM_uint32     err_major_status,       /* Major status code for display */
 341                 err_minor_status;       /* Minor status code for display */
 342   OM_uint32     msg_ctx;                /* Message context */
 343   gss_buffer_desc major_status_string = GSS_C_EMPTY_BUFFER,
 344                                         /* Major status message */
 345                 minor_status_string = GSS_C_EMPTY_BUFFER;
 346                                         /* Minor status message */
 347
 348
 349   msg_ctx          = 0;
 350   err_major_status = gss_display_status(&err_minor_status,
 351                                         major_status,
 352                                         GSS_C_GSS_CODE,
 353                                         GSS_C_NO_OID,
 354                                         &msg_ctx,
 355                                         &major_status_string);
 356
 357   if (!GSS_ERROR(err_major_status))
 358     err_major_status = gss_display_status(&err_minor_status,
 359                                           minor_status,
 360                                           GSS_C_MECH_CODE,
 361                                           GSS_C_NULL_OID,
 362                                           &msg_ctx,
 363                                           &minor_status_string);
 364
 365   printf("%s: %s, %s\n", message, (char *)major_status_string.value,
 366          (char *)minor_status_string.value);
 367
 368   gss_release_buffer(&err_minor_status, &major_status_string);
 369   gss_release_buffer(&err_minor_status, &minor_status_string);
 370 }
 371 #  endif /* DEBUG */
 372
 373
 374 /*
 375  * 'cups_get_gss_creds()' - Get CUPS service credentials for authentication.
 376  */
 377
 378 static gss_name_t                       /* O - Server name */
 379 cups_get_gss_creds(
 380     http_t     *http,                   /* I - Connection to server */
 381     const char *service_name)           /* I - Service name */
 382 {
 383   gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
 384                                         /* Service token */
 385   OM_uint32       major_status,         /* Major status code */
 386                   minor_status;         /* Minor status code */
 387   gss_name_t      server_name;          /* Server name */
 388   char            buf[1024],            /* Name buffer */
 389                   fqdn[HTTP_MAX_URI];   /* Server name buffer */
 390
 391
 392  /*
 393   * Get the hostname...
 394   */
 395
 396   httpGetHostname(http, fqdn, sizeof(fqdn));
 397
 398   if (!strcmp(fqdn, "localhost"))
 399     httpGetHostname(NULL, fqdn, sizeof(fqdn));
 400
 401  /*
 402   * Get a server name we can use for authentication purposes...
 403   */
 404
 405   snprintf(buf, sizeof(buf), "%s@%s", service_name, fqdn);
 406
 407   token.value  = buf;
 408   token.length = strlen(buf);
 409   server_name  = GSS_C_NO_NAME;
 410   major_status = gss_import_name(&minor_status, &token,
 411                                  GSS_C_NT_HOSTBASED_SERVICE,
 412                                  &server_name);
 413
 414   if (GSS_ERROR(major_status))
 415   {
 416 #  ifdef DEBUG
 417     DEBUG_gss_printf(major_status, minor_status, "gss_import_name() failed");
 418 #  endif /* DEBUG */
 419
 420     return (NULL);
 421   }
 422
 423   return (server_name);
 424 }
 425 #endif /* HAVE_GSSAPI */
 426
 427
 428 /*
 429  * 'cups_local_auth()' - Get the local authorization certificate if
 430  *                       available/applicable...
 431  */
 432
 433 static int                              /* O - 0 if available */
 434                                         /*     1 if not available */
 435                                         /*    -1 error */
 436 cups_local_auth(http_t *http)           /* I - HTTP connection to server */
 437 {
 438 #if defined(WIN32) || defined(__EMX__)
 439  /*
 440   * Currently WIN32 and OS-2 do not support the CUPS server...
 441   */
 442
 443   return (1);
 444 #else
 445   int                   pid;            /* Current process ID */
 446   FILE                  *fp;            /* Certificate file */
 447   char                  filename[1024], /* Certificate filename */
 448                         certificate[33];/* Certificate string */
 449   _cups_globals_t *cg = _cupsGlobals(); /* Global data */
 450 #  if defined(HAVE_AUTHORIZATION_H)
 451   OSStatus              status;         /* Status */
 452   AuthorizationItem     auth_right;     /* Authorization right */
 453   AuthorizationRights   auth_rights;    /* Authorization rights */
 454   AuthorizationFlags    auth_flags;     /* Authorization flags */
 455   AuthorizationExternalForm auth_extrn; /* Authorization ref external */
 456   char                  auth_key[1024]; /* Buffer */
 457   char                  buffer[1024];   /* Buffer */
 458 #  endif /* HAVE_AUTHORIZATION_H */
 459
 460
 461   DEBUG_printf(("cups_local_auth(http=%p) hostaddr=%s, hostname=\"%s\"\n",
 462                 http, httpAddrString(http->hostaddr, filename, sizeof(filename)), http->hostname));
 463
 464  /*
 465   * See if we are accessing localhost...
 466   */
 467
 468   if (!httpAddrLocalhost(http->hostaddr) &&
 469       strcasecmp(http->hostname, "localhost") != 0)
 470   {
 471     DEBUG_puts("cups_local_auth: Not a local connection!");
 472     return (1);
 473   }
 474
 475 #  if defined(HAVE_AUTHORIZATION_H)
 476  /*
 477   * Delete any previous authorization reference...
 478   */
 479
 480   if (http->auth_ref)
 481   {
 482     AuthorizationFree(http->auth_ref, kAuthorizationFlagDefaults);
 483     http->auth_ref = NULL;
 484   }
 485
 486   if (httpGetSubField2(http, HTTP_FIELD_WWW_AUTHENTICATE, "authkey",
 487                        auth_key, sizeof(auth_key)))
 488   {
 489     status = AuthorizationCreate(NULL, kAuthorizationEmptyEnvironment,
 490                                  kAuthorizationFlagDefaults, &http->auth_ref);
 491     if (status != errAuthorizationSuccess)
 492     {
 493       DEBUG_printf(("cups_local_auth: AuthorizationCreate() returned %d (%s)\n",
 494                     (int)status, cssmErrorString(status)));
 495       return (-1);
 496     }
 497
 498     auth_right.name        = auth_key;
 499     auth_right.valueLength = 0;
 500     auth_right.value       = NULL;
 501     auth_right.flags       = 0;
 502
 503     auth_rights.count = 1;
 504     auth_rights.items = &auth_right;
 505
 506     auth_flags = kAuthorizationFlagDefaults |
 507                  kAuthorizationFlagPreAuthorize |
 508                  kAuthorizationFlagInteractionAllowed |
 509                  kAuthorizationFlagExtendRights;
 510
 511     status = AuthorizationCopyRights(http->auth_ref, &auth_rights,
 512                                      kAuthorizationEmptyEnvironment,
 513                                      auth_flags, NULL);
 514     if (status == errAuthorizationSuccess)
 515       status = AuthorizationMakeExternalForm(http->auth_ref, &auth_extrn);
 516
 517     if (status == errAuthorizationSuccess)
 518     {
 519      /*
 520       * Set the authorization string and return...
 521       */
 522
 523       httpEncode64_2(buffer, sizeof(buffer), (void *)&auth_extrn,
 524                      sizeof(auth_extrn));
 525
 526       http->authstring = malloc(strlen(buffer) + 9);
 527       sprintf(http->authstring, "AuthRef %s", buffer);
 528
 529       /* Copy back to _authstring for backwards compatibility */
 530       strlcpy(http->_authstring, http->authstring, sizeof(http->_authstring));
 531
 532       DEBUG_printf(("cups_local_auth: Returning authstring = \"%s\"\n",
 533                     http->authstring));
 534       return (0);
 535     }
 536     else if (status == errAuthorizationCanceled)
 537       return (-1);
 538
 539     DEBUG_printf(("cups_local_auth: AuthorizationCopyRights() returned %d (%s)\n",
 540                   (int)status, cssmErrorString(status)));
 541
 542   /*
 543    * Fall through to try certificates...
 544    */
 545   }
 546 #  endif /* HAVE_AUTHORIZATION_H */
 547
 548  /*
 549   * Try opening a certificate file for this PID.  If that fails,
 550   * try the root certificate...
 551   */
 552
 553   pid = getpid();
 554   snprintf(filename, sizeof(filename), "%s/certs/%d", cg->cups_statedir, pid);
 555   if ((fp = fopen(filename, "r")) == NULL && pid > 0)
 556   {
 557     DEBUG_printf(("cups_local_auth: Unable to open file %s: %s\n",
 558                   filename, strerror(errno)));
 559
 560 #ifdef HAVE_GSSAPI
 561    /*
 562     * If local certificate authentication isn't available for this PID,
 563     * check if we need Kerberos authentication...
 564     */
 565
 566     if (!strcmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE], "Negotiate"))
 567     {
 568      /*
 569       * Yes, don't try the root certificate...
 570       */
 571
 572       return (1);
 573     }
 574 #endif /* HAVE_GSSAPI */
 575
 576     snprintf(filename, sizeof(filename), "%s/certs/0", cg->cups_statedir);
 577     fp = fopen(filename, "r");
 578   }
 579
 580   if (fp)
 581   {
 582    /*
 583     * Read the certificate from the file...
 584     */
 585
 586     fgets(certificate, sizeof(certificate), fp);
 587     fclose(fp);
 588
 589    /*
 590     * Set the authorization string and return...
 591     */
 592
 593     http->authstring = malloc(strlen(certificate) + 7);
 594     sprintf(http->authstring, "Local %s", certificate);
 595
 596     /* Copy back to _authstring for backwards compatibility */
 597     strlcpy(http->_authstring, http->authstring, sizeof(http->_authstring));
 598
 599     DEBUG_printf(("cups_local_auth: Returning authstring = \"%s\"\n",
 600                   http->authstring));
 601
 602     return (0);
 603   }
 604
 605 #  if defined(SO_PEERCRED) && defined(AF_LOCAL)
 606  /*
 607   * See if we can authenticate using the peer credentials provided over a
 608   * domain socket; if so, specify "PeerCred username" as the authentication
 609   * information...
 610   */
 611
 612   if (http->hostaddr->addr.sa_family == AF_LOCAL &&
 613       !getenv("GATEWAY_INTERFACE"))     /* Not via CGI programs... */
 614   {
 615    /*
 616     * Verify that the current cupsUser() matches the current UID...
 617     */
 618
 619     struct passwd       *pwd;           /* Password information */
 620     const char          *username;      /* Current username */
 621
 622     username = cupsUser();
 623
 624     if ((pwd = getpwnam(username)) != NULL && pwd->pw_uid == getuid())
 625     {
 626       http->authstring = malloc(strlen(username) + 10);
 627       sprintf(http->authstring, "PeerCred %s", username);
 628
 629       /* Copy back to _authstring for backwards compatibility */
 630       strlcpy(http->_authstring, http->authstring, sizeof(http->_authstring));
 631
 632       DEBUG_printf(("cups_local_auth: Returning authstring = \"%s\"\n",
 633                     http->authstring));
 634
 635       return (0);
 636     }
 637   }
 638 #  endif /* SO_PEERCRED && AF_LOCAL */
 639
 640   return (1);
 641 #endif /* WIN32 || __EMX__ */
 642 }
 643
 644
 645 /*
 646  * End of "$Id: auth.c 6673 2007-07-14 00:16:39Z mike $".
 647  */