cups/auth.c

   1 /*
   2  * "$Id$"
   3  *
   4  *   Authentication functions for the Common UNIX Printing System (CUPS).
   5  *
   6  *   Copyright 1997-2006 by Easy Software Products.
   7  *
   8  *   This file contains Kerberos support code, copyright 2006 by
   9  *   Jelmer Vernooij.
  10  *
  11  *   These coded instructions, statements, and computer programs are the
  12  *   property of Easy Software Products and are protected by Federal
  13  *   copyright law.  Distribution and use rights are outlined in the file
  14  *   "LICENSE.txt" which should have been included with this file.  If this
  15  *   file is missing or damaged please contact Easy Software Products
  16  *   at:
  17  *
  18  *       Attn: CUPS Licensing Information
  19  *       Easy Software Products
  20  *       44141 Airport View Drive, Suite 204
  21  *       Hollywood, Maryland 20636 USA
  22  *
  23  *       Voice: (301) 373-9600
  24  *       EMail: cups-info@cups.org
  25  *         WWW: http://www.cups.org
  26  *
  27  *   This file is subject to the Apple OS-Developed Software exception.
  28  *
  29  * Contents:
  30  *
  31  *   cupsDoAuthentication() - Authenticate a request.
  32  *   DEBUG_gss_printf()     - Show debug error messages from GSSAPI...
  33  *   cups_get_gss_creds()   - Get CUPS service credentials for authentication.
  34  *   cups_local_auth()      - Get the local authorization certificate if
  35  *                            available/applicable...
  36  */
  37
  38 /*
  39  * Include necessary headers...
  40  */
  41
  42 #include "globals.h"
  43 #include "debug.h"
  44 #include <stdlib.h>
  45 #include <ctype.h>
  46 #include <errno.h>
  47 #include <fcntl.h>
  48 #include <sys/stat.h>
  49 #if defined(WIN32) || defined(__EMX__)
  50 #  include <io.h>
  51 #else
  52 #  include <unistd.h>
  53 #endif /* WIN32 || __EMX__ */
  54
  55
  56 /*
  57  * Local functions...
  58  */
  59
  60 #ifdef HAVE_GSSAPI
  61 #  ifdef DEBUG
  62 static void     DEBUG_gss_printf(OM_uint32 major_status, OM_uint32 minor_status,
  63                                  const char *message);
  64 #  endif /* DEBUG  */
  65 static gss_name_t cups_get_gss_creds(http_t *http, const char *service_name);
  66 #endif /* HAVE_GSSAPI */
  67 static int      cups_local_auth(http_t *http);
  68
  69
  70 /*
  71  * 'cupsDoAuthentication()' - Authenticate a request.
  72  *
  73  * This function should be called in response to a HTTP_UNAUTHORIZED
  74  * status, prior to resubmitting your request.
  75  *
  76  * @since CUPS 1.1.20@
  77  */
  78
  79 int                                     /* O - 0 on success, -1 on error */
  80 cupsDoAuthentication(http_t     *http,  /* I - HTTP connection to server */
  81                      const char *method,/* I - Request method (GET, POST, PUT) */
  82                      const char *resource)
  83                                         /* I - Resource path */
  84 {
  85   const char    *password;              /* Password string */
  86   char          prompt[1024],           /* Prompt for user */
  87                 realm[HTTP_MAX_VALUE],  /* realm="xyz" string */
  88                 nonce[HTTP_MAX_VALUE],  /* nonce="xyz" string */
  89                 encode[2048];           /* Encoded username:password */
  90
  91
  92   DEBUG_printf(("cupsDoAuthentication(http=%p, method=\"%s\", resource=\"%s\")\n",
  93                 http, method, resource));
  94   DEBUG_printf(("cupsDoAuthentication: digest_tries=%d, userpass=\"%s\"\n",
  95                 http->digest_tries, http->userpass));
  96   DEBUG_printf(("cupsDoAuthentication: WWW-Authenticate=\"%s\"\n",
  97                 httpGetField(http, HTTP_FIELD_WWW_AUTHENTICATE)));
  98
  99  /*
 100   * Clear the current authentication string...
 101   */
 102
 103   http->_authstring[0] = '\0';
 104
 105   if (http->authstring && http->authstring != http->_authstring)
 106     free(http->authstring);
 107
 108   http->authstring = http->_authstring;
 109
 110  /*
 111   * See if we can do local authentication...
 112   */
 113
 114   if (http->digest_tries < 3 && !cups_local_auth(http))
 115   {
 116     DEBUG_printf(("cupsDoAuthentication: authstring=\"%s\"\n", http->authstring));
 117
 118     if (http->status == HTTP_UNAUTHORIZED)
 119       http->digest_tries ++;
 120
 121     return (0);
 122   }
 123
 124  /*
 125   * Nope, see if we should retry the current username:password...
 126   */
 127
 128   if ((http->digest_tries > 1 || !http->userpass[0]) &&
 129       strncmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE], "Negotiate", 9))
 130   {
 131    /*
 132     * Nope - get a new password from the user...
 133     */
 134
 135     snprintf(prompt, sizeof(prompt), _("Password for %s on %s? "), cupsUser(),
 136              http->hostname[0] == '/' ? "localhost" : http->hostname);
 137
 138     http->digest_tries  = strncasecmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE],
 139                                       "Digest", 5) != 0;
 140     http->userpass[0]   = '\0';
 141
 142     if ((password = cupsGetPassword(prompt)) == NULL)
 143       return (-1);
 144
 145     if (!password[0])
 146       return (-1);
 147
 148     snprintf(http->userpass, sizeof(http->userpass), "%s:%s", cupsUser(),
 149              password);
 150   }
 151   else if (http->status == HTTP_UNAUTHORIZED)
 152     http->digest_tries ++;
 153
 154  /*
 155   * Got a password; encode it for the server...
 156   */
 157
 158   if (!strncmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE], "Negotiate", 9))
 159   {
 160 #ifdef HAVE_GSSAPI
 161    /*
 162     * Kerberos authentication...
 163     */
 164
 165     OM_uint32           minor_status,   /* Minor status code */
 166                         major_status;   /* Major status code */
 167     gss_buffer_desc     output_token = GSS_C_EMPTY_BUFFER,
 168                                         /* Output token */
 169                         input_token = GSS_C_EMPTY_BUFFER;
 170                                         /* Input token */
 171     char                *gss_service_name;
 172                                         /* GSS service name */
 173     const char          *authorization;
 174                                         /* Pointer into Authorization string */
 175
 176
 177     if (http->gssname == GSS_C_NO_NAME)
 178     {
 179       if ((gss_service_name = getenv("CUPS_GSSSERVICENAME")) == NULL)
 180         gss_service_name = CUPS_DEFAULT_GSSSERVICENAME;
 181       else
 182         DEBUG_puts("cupsDoAuthentication: GSS service name set via environment");
 183
 184       http->gssname = cups_get_gss_creds(http, gss_service_name);
 185     }
 186
 187    /*
 188     * Find the start of the Kerberos input token...
 189     */
 190
 191     authorization = httpGetField(http, HTTP_FIELD_WWW_AUTHENTICATE);
 192
 193     authorization += 9;
 194     while (*authorization && isspace(*authorization & 255))
 195       authorization ++;
 196
 197     if (*authorization)
 198     {
 199      /*
 200       * For SPNEGO, this is where we'll feed the server's authorization data
 201       * back into gss via input_token...
 202       */
 203     }
 204     else
 205     {
 206       if (http->gssctx != GSS_C_NO_CONTEXT)
 207       {
 208         major_status = gss_delete_sec_context(&minor_status, &http->gssctx,
 209                                               GSS_C_NO_BUFFER);
 210         http->gssctx = GSS_C_NO_CONTEXT;
 211       }
 212     }
 213
 214     major_status  = gss_init_sec_context(&minor_status, GSS_C_NO_CREDENTIAL,
 215                                          &http->gssctx,
 216                                          http->gssname, http->gssmech,
 217                                          GSS_C_MUTUAL_FLAG, GSS_C_INDEFINITE,
 218                                          GSS_C_NO_CHANNEL_BINDINGS,
 219                                          &input_token, &http->gssmech,
 220                                          &output_token, NULL, NULL);
 221
 222     if (input_token.value)
 223       free(input_token.value);
 224
 225     if (GSS_ERROR(major_status))
 226     {
 227 #  ifdef DEBUG
 228       DEBUG_gss_printf(major_status, minor_status,
 229                        "Unable to initialise security context");
 230 #  endif /* DEBUG */
 231       return (-1);
 232     }
 233
 234 #  ifdef DEBUG
 235     if (major_status == GSS_S_CONTINUE_NEEDED)
 236       DEBUG_gss_printf(major_status, minor_status, "Continuation needed!");
 237 #  endif /* DEBUG */
 238
 239     if (output_token.length)
 240     {
 241       httpEncode64_2(encode, sizeof(encode), output_token.value,
 242                      output_token.length);
 243
 244       http->authstring = malloc(strlen(encode) + 11);
 245       sprintf(http->authstring, "Negotiate %s", encode); /* Safe because allocated */
 246
 247       major_status = gss_release_buffer(&minor_status, &output_token);
 248     }
 249
 250    /*
 251     * Copy back what we can to _authstring for backwards compatibility...
 252     */
 253
 254     strlcpy(http->_authstring, http->authstring, sizeof(http->_authstring));
 255 #endif /* HAVE_GSSAPI */
 256   }
 257   else if (strncmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE], "Digest", 6))
 258   {
 259    /*
 260     * Basic authentication...
 261     */
 262
 263     httpEncode64_2(encode, sizeof(encode), http->userpass,
 264                    strlen(http->userpass));
 265     snprintf(http->_authstring, sizeof(http->_authstring), "Basic %s", encode);
 266   }
 267   else
 268   {
 269    /*
 270     * Digest authentication...
 271     */
 272
 273     httpGetSubField(http, HTTP_FIELD_WWW_AUTHENTICATE, "realm", realm);
 274     httpGetSubField(http, HTTP_FIELD_WWW_AUTHENTICATE, "nonce", nonce);
 275
 276     httpMD5(cupsUser(), realm, strchr(http->userpass, ':') + 1, encode);
 277     httpMD5Final(nonce, method, resource, encode);
 278     snprintf(http->_authstring, sizeof(http->_authstring),
 279              "Digest username=\"%s\", realm=\"%s\", nonce=\"%s\", "
 280              "uri=\"%s\", response=\"%s\"", cupsUser(), realm, nonce,
 281              resource, encode);
 282   }
 283
 284   DEBUG_printf(("cupsDoAuthentication: authstring=\"%s\"\n", http->authstring));
 285
 286   return (0);
 287 }
 288
 289
 290 #ifdef HAVE_GSSAPI
 291 #  ifdef DEBUG
 292 /*
 293  * 'DEBUG_gss_printf()' - Show debug error messages from GSSAPI...
 294  */
 295
 296 static void
 297 DEBUG_gss_printf(OM_uint32 major_status,/* I - Major status code */
 298                  OM_uint32 minor_status,/* I - Minor status code */
 299                  const char *message)   /* I - Prefix for error message */
 300 {
 301   OM_uint32     err_major_status,       /* Major status code for display */
 302                 err_minor_status;       /* Minor status code for display */
 303   OM_uint32     msg_ctx;                /* Message context */
 304   gss_buffer_desc major_status_string = GSS_C_EMPTY_BUFFER,
 305                                         /* Major status message */
 306                 minor_status_string = GSS_C_EMPTY_BUFFER;
 307                                         /* Minor status message */
 308
 309
 310   msg_ctx          = 0;
 311   err_major_status = gss_display_status(&err_minor_status,
 312                                         major_status,
 313                                         GSS_C_GSS_CODE,
 314                                         GSS_C_NO_OID,
 315                                         &msg_ctx,
 316                                         &major_status_string);
 317
 318   if (!GSS_ERROR(err_major_status))
 319     err_major_status = gss_display_status(&err_minor_status,
 320                                           minor_status,
 321                                           GSS_C_MECH_CODE,
 322                                           GSS_C_NULL_OID,
 323                                           &msg_ctx,
 324                                           &minor_status_string);
 325
 326   printf("%s: %s, %s\n", message, (char *)major_status_string.value,
 327          (char *)minor_status_string.value);
 328
 329   gss_release_buffer(&err_minor_status, &major_status_string);
 330   gss_release_buffer(&err_minor_status, &minor_status_string);
 331 }
 332 #  endif /* DEBUG */
 333
 334
 335 /*
 336  * 'cups_get_gss_creds()' - Get CUPS service credentials for authentication.
 337  */
 338
 339 static gss_name_t                       /* O - Server name */
 340 cups_get_gss_creds(
 341     http_t     *http,                   /* I - Connection to server */
 342     const char *service_name)           /* I - Service name */
 343 {
 344   gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
 345                                         /* Service token */
 346   OM_uint32     major_status,           /* Major status code */
 347                 minor_status;           /* Minor status code */
 348   gss_name_t    server_name;            /* Server name */
 349   char          buf[1024],              /* Name buffer */
 350                 fqdn[HTTP_MAX_URI];     /* Server name buffer */
 351
 352
 353  /*
 354   * Get a server name we can use for authentication purposes...
 355   */
 356
 357   snprintf(buf, sizeof(buf), "%s@%s", service_name,
 358            httpGetHostname(http, fqdn, sizeof(fqdn)));
 359
 360   token.value  = buf;
 361   token.length = strlen(buf);
 362   server_name  = GSS_C_NO_NAME;
 363   major_status = gss_import_name(&minor_status, &token,
 364                                  GSS_C_NT_HOSTBASED_SERVICE,
 365                                  &server_name);
 366
 367   if (GSS_ERROR(major_status))
 368   {
 369 #  ifdef DEBUG
 370     DEBUG_gss_printf(major_status, minor_status, "gss_import_name() failed");
 371 #  endif /* DEBUG */
 372
 373     return (NULL);
 374   }
 375
 376   return (server_name);
 377 }
 378 #endif /* HAVE_GSSAPI */
 379
 380
 381 /*
 382  * 'cups_local_auth()' - Get the local authorization certificate if
 383  *                       available/applicable...
 384  */
 385
 386 static int                              /* O - 0 if available, -1 if not */
 387 cups_local_auth(http_t *http)           /* I - HTTP connection to server */
 388 {
 389 #if defined(WIN32) || defined(__EMX__)
 390  /*
 391   * Currently WIN32 and OS-2 do not support the CUPS server...
 392   */
 393
 394   return (-1);
 395 #else
 396   int           pid;                    /* Current process ID */
 397   FILE          *fp;                    /* Certificate file */
 398   char          filename[1024],         /* Certificate filename */
 399                 certificate[33];        /* Certificate string */
 400   _cups_globals_t *cg = _cupsGlobals(); /* Global data */
 401
 402
 403   DEBUG_printf(("cups_local_auth(http=%p) hostaddr=%s, hostname=\"%s\"\n",
 404                 http, httpAddrString(http->hostaddr, filename, sizeof(filename)), http->hostname));
 405
 406  /*
 407   * See if we are accessing localhost...
 408   */
 409
 410   if (!httpAddrLocalhost(http->hostaddr) &&
 411       strcasecmp(http->hostname, "localhost") != 0)
 412   {
 413     DEBUG_puts("cups_local_auth: Not a local connection!");
 414     return (-1);
 415   }
 416
 417  /*
 418   * Try opening a certificate file for this PID.  If that fails,
 419   * try the root certificate...
 420   */
 421
 422   pid = getpid();
 423   snprintf(filename, sizeof(filename), "%s/certs/%d", cg->cups_statedir, pid);
 424   if ((fp = fopen(filename, "r")) == NULL && pid > 0)
 425   {
 426     DEBUG_printf(("cups_local_auth: Unable to open file %s: %s\n",
 427                   filename, strerror(errno)));
 428
 429     snprintf(filename, sizeof(filename), "%s/certs/0", cg->cups_statedir);
 430     fp = fopen(filename, "r");
 431   }
 432
 433   if (fp == NULL)
 434   {
 435     DEBUG_printf(("cups_local_auth: Unable to open file %s: %s\n",
 436                   filename, strerror(errno)));
 437     return (-1);
 438   }
 439
 440  /*
 441   * Read the certificate from the file...
 442   */
 443
 444   fgets(certificate, sizeof(certificate), fp);
 445   fclose(fp);
 446
 447  /*
 448   * Set the authorization string and return...
 449   */
 450
 451   http->authstring = malloc(strlen(certificate) + 10);
 452   sprintf(http->authstring, "Local %s", certificate);
 453
 454   /* Copy back to _authstring for backwards compatibility */
 455   strlcpy(http->_authstring, http->authstring, sizeof(http->_authstring));
 456
 457   DEBUG_printf(("cups_local_auth: Returning authstring = \"%s\"\n",
 458                 http->authstring));
 459
 460   return (0);
 461 #endif /* WIN32 || __EMX__ */
 462 }
 463
 464
 465 /*
 466  * End of "$Id$".
 467  */