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1 /*
2 * "$Id: auth.c 6779 2007-08-08 19:49:48Z mike $"
3 *
4 * Authentication functions for the Common UNIX Printing System (CUPS).
5 *
6 * Copyright 2007-2008 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 # else
69 # define DEBUG_gss_printf(major, minor, message)
70 # endif /* DEBUG */
71 static gss_name_t cups_get_gss_creds(http_t *http, const char *service_name);
72 #endif /* HAVE_GSSAPI */
73 static int cups_local_auth(http_t *http);
74
75
76 /*
77 * 'cupsDoAuthentication()' - Authenticate a request.
78 *
79 * This function should be called in response to a @code HTTP_UNAUTHORIZED@
80 * status, prior to resubmitting your request.
81 *
82 * @since CUPS 1.1.20@
83 */
84
85 int /* O - 0 on success, -1 on error */
86 cupsDoAuthentication(http_t *http, /* I - HTTP connection to server */
87 const char *method,/* I - Request method ("GET", "POST", "PUT") */
88 const char *resource)
89 /* I - Resource path */
90 {
91 const char *password; /* Password string */
92 char prompt[1024], /* Prompt for user */
93 realm[HTTP_MAX_VALUE], /* realm="xyz" string */
94 nonce[HTTP_MAX_VALUE]; /* nonce="xyz" string */
95 int localauth; /* Local authentication result */
96 _cups_globals_t *cg; /* Global data */
97
98
99 DEBUG_printf(("cupsDoAuthentication(http=%p, method=\"%s\", resource=\"%s\")\n",
100 http, method, resource));
101 DEBUG_printf(("cupsDoAuthentication: digest_tries=%d, userpass=\"%s\"\n",
102 http->digest_tries, http->userpass));
103 DEBUG_printf(("cupsDoAuthentication: WWW-Authenticate=\"%s\"\n",
104 httpGetField(http, HTTP_FIELD_WWW_AUTHENTICATE)));
105
106 /*
107 * Clear the current authentication string...
108 */
109
110 httpSetAuthString(http, NULL, NULL);
111
112 /*
113 * See if we can do local authentication...
114 */
115
116 if (http->digest_tries < 3)
117 {
118 if ((localauth = cups_local_auth(http)) == 0)
119 {
120 DEBUG_printf(("cupsDoAuthentication: authstring=\"%s\"\n",
121 http->authstring));
122
123 if (http->status == HTTP_UNAUTHORIZED)
124 http->digest_tries ++;
125
126 return (0);
127 }
128 else if (localauth == -1)
129 return (-1); /* Error or canceled */
130 }
131
132 /*
133 * Nope, see if we should retry the current username:password...
134 */
135
136 if ((http->digest_tries > 1 || !http->userpass[0]) &&
137 strncmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE], "Negotiate", 9))
138 {
139 /*
140 * Nope - get a new password from the user...
141 */
142
143 cg = _cupsGlobals();
144
145 if (!cg->lang_default)
146 cg->lang_default = cupsLangDefault();
147
148 snprintf(prompt, sizeof(prompt),
149 _cupsLangString(cg->lang_default, _("Password for %s on %s? ")),
150 cupsUser(),
151 http->hostname[0] == '/' ? "localhost" : http->hostname);
152
153 http->digest_tries = strncasecmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE],
154 "Digest", 5) != 0;
155 http->userpass[0] = '\0';
156
157 if ((password = cupsGetPassword(prompt)) == NULL)
158 return (-1);
159
160 if (!password[0])
161 return (-1);
162
163 snprintf(http->userpass, sizeof(http->userpass), "%s:%s", cupsUser(),
164 password);
165 }
166 else if (http->status == HTTP_UNAUTHORIZED)
167 http->digest_tries ++;
168
169 /*
170 * Got a password; encode it for the server...
171 */
172
173 if (!strncmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE], "Negotiate", 9))
174 {
175 #ifdef HAVE_GSSAPI
176 /*
177 * Kerberos authentication...
178 */
179
180 OM_uint32 minor_status, /* Minor status code */
181 major_status; /* Major status code */
182 gss_buffer_desc output_token = GSS_C_EMPTY_BUFFER,
183 /* Output token */
184 input_token = GSS_C_EMPTY_BUFFER;
185 /* Input token */
186 char *gss_service_name;
187 /* GSS service name */
188 # ifdef USE_SPNEGO
189 const char *authorization;
190 /* Pointer into Authorization string */
191 # endif /* USE_SPNEGO */
192
193
194 # ifdef __APPLE__
195 /*
196 * If the weak-linked GSSAPI/Kerberos library is not present, don't try
197 * to use it...
198 */
199
200 if (gss_init_sec_context == NULL)
201 {
202 DEBUG_puts("cupsDoAuthentication: Weak-linked GSSAPI/Kerberos framework "
203 "is not present");
204 return (-1);
205 }
206 # endif /* __APPLE__ */
207
208 if (http->status == HTTP_UNAUTHORIZED && http->digest_tries >= 3)
209 {
210 DEBUG_printf(("cupsDoAuthentication: too many Negotiate tries (%d)\n",
211 http->digest_tries));
212
213 return (-1);
214 }
215
216 if (http->gssname == GSS_C_NO_NAME)
217 {
218 if ((gss_service_name = getenv("CUPS_GSSSERVICENAME")) == NULL)
219 gss_service_name = CUPS_DEFAULT_GSSSERVICENAME;
220 else
221 DEBUG_puts("cupsDoAuthentication: GSS service name set via environment");
222
223 http->gssname = cups_get_gss_creds(http, gss_service_name);
224 }
225
226 # ifdef USE_SPNEGO /* We don't implement SPNEGO just yet... */
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 * Decode the authorization string to get the input token...
241 */
242
243 int len = strlen(authorization);
244
245 input_token.value = malloc(len);
246 input_token.value = httpDecode64_2(input_token.value, &len,
247 authorization);
248 input_token.length = len;
249
250 # ifdef DEBUG
251 {
252 char *ptr = (char *)input_token.value;
253 int left = len;
254
255 fputs("input_token=", stdout);
256 while (left > 0)
257 {
258 if (*ptr < ' ')
259 printf("\\%03o", *ptr & 255);
260 else
261 putchar(*ptr);
262 ptr ++;
263 left --;
264 }
265 putchar('\n');
266 }
267 # endif /* DEBUG */
268 }
269 # endif /* USE_SPNEGO */
270
271 if (http->gssctx != GSS_C_NO_CONTEXT)
272 {
273 major_status = gss_delete_sec_context(&minor_status, &http->gssctx,
274 GSS_C_NO_BUFFER);
275 http->gssctx = GSS_C_NO_CONTEXT;
276 }
277
278 major_status = gss_init_sec_context(&minor_status, GSS_C_NO_CREDENTIAL,
279 &http->gssctx,
280 http->gssname, http->gssmech,
281 GSS_C_DELEG_FLAG | GSS_C_MUTUAL_FLAG |
282 GSS_C_INTEG_FLAG,
283 GSS_C_INDEFINITE,
284 GSS_C_NO_CHANNEL_BINDINGS,
285 &input_token, &http->gssmech,
286 &output_token, NULL, NULL);
287
288 if (input_token.value)
289 free(input_token.value);
290
291 if (GSS_ERROR(major_status))
292 {
293 # ifdef DEBUG
294 DEBUG_gss_printf(major_status, minor_status,
295 "Unable to initialize security context");
296 # endif /* DEBUG */
297 return (-1);
298 }
299
300 if (major_status == GSS_S_CONTINUE_NEEDED)
301 DEBUG_gss_printf(major_status, minor_status, "Continuation needed!");
302
303 if (output_token.length > 0 && output_token.length <= 65536)
304 {
305 /*
306 * Allocate the authorization string since Windows KDCs can have
307 * arbitrarily large credentials...
308 */
309
310 int authsize = 10 + /* "Negotiate " */
311 output_token.length * 4 / 3 + 1 + /* Base64 */
312 1; /* nul */
313
314 httpSetAuthString(http, NULL, NULL);
315
316 if ((http->authstring = malloc(authsize)) == NULL)
317 {
318 http->authstring = http->_authstring;
319 authsize = sizeof(http->_authstring);
320 }
321
322 strcpy(http->authstring, "Negotiate ");
323 httpEncode64_2(http->authstring + 10, authsize - 10, output_token.value,
324 output_token.length);
325
326 major_status = gss_release_buffer(&minor_status, &output_token);
327 }
328 else
329 {
330 DEBUG_printf(("cupsDoAuthentication: Kerberos credentials too large - "
331 "%d bytes!\n", output_token.length));
332
333 major_status = gss_release_buffer(&minor_status, &output_token);
334
335 return (-1);
336 }
337 #endif /* HAVE_GSSAPI */
338 }
339 else if (strncmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE], "Digest", 6))
340 {
341 /*
342 * Basic authentication...
343 */
344
345 char encode[256]; /* Base64 buffer */
346
347
348 httpEncode64_2(encode, sizeof(encode), http->userpass,
349 (int)strlen(http->userpass));
350 httpSetAuthString(http, "Basic", encode);
351 }
352 else
353 {
354 /*
355 * Digest authentication...
356 */
357
358 char encode[33], /* MD5 buffer */
359 digest[1024]; /* Digest auth data */
360
361
362 httpGetSubField(http, HTTP_FIELD_WWW_AUTHENTICATE, "realm", realm);
363 httpGetSubField(http, HTTP_FIELD_WWW_AUTHENTICATE, "nonce", nonce);
364
365 httpMD5(cupsUser(), realm, strchr(http->userpass, ':') + 1, encode);
366 httpMD5Final(nonce, method, resource, encode);
367 snprintf(digest, sizeof(digest),
368 "username=\"%s\", realm=\"%s\", nonce=\"%s\", uri=\"%s\", "
369 "response=\"%s\"", cupsUser(), realm, nonce, resource, encode);
370 httpSetAuthString(http, "Digest", digest);
371 }
372
373 DEBUG_printf(("cupsDoAuthentication: authstring=\"%s\"\n", http->authstring));
374
375 return (0);
376 }
377
378
379 #ifdef HAVE_GSSAPI
380 # ifdef DEBUG
381 /*
382 * 'DEBUG_gss_printf()' - Show debug error messages from GSSAPI...
383 */
384
385 static void
386 DEBUG_gss_printf(OM_uint32 major_status,/* I - Major status code */
387 OM_uint32 minor_status,/* I - Minor status code */
388 const char *message) /* I - Prefix for error message */
389 {
390 OM_uint32 err_major_status, /* Major status code for display */
391 err_minor_status; /* Minor status code for display */
392 OM_uint32 msg_ctx; /* Message context */
393 gss_buffer_desc major_status_string = GSS_C_EMPTY_BUFFER,
394 /* Major status message */
395 minor_status_string = GSS_C_EMPTY_BUFFER;
396 /* Minor status message */
397
398
399 msg_ctx = 0;
400 err_major_status = gss_display_status(&err_minor_status,
401 major_status,
402 GSS_C_GSS_CODE,
403 GSS_C_NO_OID,
404 &msg_ctx,
405 &major_status_string);
406
407 if (!GSS_ERROR(err_major_status))
408 err_major_status = gss_display_status(&err_minor_status,
409 minor_status,
410 GSS_C_MECH_CODE,
411 GSS_C_NULL_OID,
412 &msg_ctx,
413 &minor_status_string);
414
415 printf("%s: %s, %s\n", message, (char *)major_status_string.value,
416 (char *)minor_status_string.value);
417
418 gss_release_buffer(&err_minor_status, &major_status_string);
419 gss_release_buffer(&err_minor_status, &minor_status_string);
420 }
421 # endif /* DEBUG */
422
423
424 /*
425 * 'cups_get_gss_creds()' - Get CUPS service credentials for authentication.
426 */
427
428 static gss_name_t /* O - Server name */
429 cups_get_gss_creds(
430 http_t *http, /* I - Connection to server */
431 const char *service_name) /* I - Service name */
432 {
433 gss_buffer_desc token = GSS_C_EMPTY_BUFFER;
434 /* Service token */
435 OM_uint32 major_status, /* Major status code */
436 minor_status; /* Minor status code */
437 gss_name_t server_name; /* Server name */
438 char buf[1024], /* Name buffer */
439 fqdn[HTTP_MAX_URI]; /* Server name buffer */
440
441
442 /*
443 * Get the hostname...
444 */
445
446 httpGetHostname(http, fqdn, sizeof(fqdn));
447
448 if (!strcmp(fqdn, "localhost"))
449 httpGetHostname(NULL, fqdn, sizeof(fqdn));
450
451 /*
452 * Get a server name we can use for authentication purposes...
453 */
454
455 snprintf(buf, sizeof(buf), "%s@%s", service_name, fqdn);
456
457 DEBUG_printf(("cups_get_gss_creds: Looking up %s...\n", buf));
458
459 token.value = buf;
460 token.length = strlen(buf);
461 server_name = GSS_C_NO_NAME;
462 major_status = gss_import_name(&minor_status, &token,
463 GSS_C_NT_HOSTBASED_SERVICE,
464 &server_name);
465
466 if (GSS_ERROR(major_status))
467 {
468 # ifdef DEBUG
469 DEBUG_gss_printf(major_status, minor_status, "gss_import_name() failed");
470 # endif /* DEBUG */
471
472 return (NULL);
473 }
474
475 return (server_name);
476 }
477 #endif /* HAVE_GSSAPI */
478
479
480 /*
481 * 'cups_local_auth()' - Get the local authorization certificate if
482 * available/applicable...
483 */
484
485 static int /* O - 0 if available */
486 /* 1 if not available */
487 /* -1 error */
488 cups_local_auth(http_t *http) /* I - HTTP connection to server */
489 {
490 #if defined(WIN32) || defined(__EMX__)
491 /*
492 * Currently WIN32 and OS-2 do not support the CUPS server...
493 */
494
495 return (1);
496 #else
497 int pid; /* Current process ID */
498 FILE *fp; /* Certificate file */
499 char filename[1024], /* Certificate filename */
500 certificate[33];/* Certificate string */
501 _cups_globals_t *cg = _cupsGlobals(); /* Global data */
502 # if defined(HAVE_AUTHORIZATION_H)
503 OSStatus status; /* Status */
504 AuthorizationItem auth_right; /* Authorization right */
505 AuthorizationRights auth_rights; /* Authorization rights */
506 AuthorizationFlags auth_flags; /* Authorization flags */
507 AuthorizationExternalForm auth_extrn; /* Authorization ref external */
508 char auth_key[1024]; /* Buffer */
509 char buffer[1024]; /* Buffer */
510 # endif /* HAVE_AUTHORIZATION_H */
511
512
513 DEBUG_printf(("cups_local_auth(http=%p) hostaddr=%s, hostname=\"%s\"\n",
514 http, httpAddrString(http->hostaddr, filename, sizeof(filename)), http->hostname));
515
516 /*
517 * See if we are accessing localhost...
518 */
519
520 if (!httpAddrLocalhost(http->hostaddr) &&
521 strcasecmp(http->hostname, "localhost") != 0)
522 {
523 DEBUG_puts("cups_local_auth: Not a local connection!");
524 return (1);
525 }
526
527 # if defined(HAVE_AUTHORIZATION_H)
528 /*
529 * Delete any previous authorization reference...
530 */
531
532 if (http->auth_ref)
533 {
534 AuthorizationFree(http->auth_ref, kAuthorizationFlagDefaults);
535 http->auth_ref = NULL;
536 }
537
538 if (httpGetSubField2(http, HTTP_FIELD_WWW_AUTHENTICATE, "authkey",
539 auth_key, sizeof(auth_key)))
540 {
541 status = AuthorizationCreate(NULL, kAuthorizationEmptyEnvironment,
542 kAuthorizationFlagDefaults, &http->auth_ref);
543 if (status != errAuthorizationSuccess)
544 {
545 DEBUG_printf(("cups_local_auth: AuthorizationCreate() returned %d (%s)\n",
546 (int)status, cssmErrorString(status)));
547 return (-1);
548 }
549
550 auth_right.name = auth_key;
551 auth_right.valueLength = 0;
552 auth_right.value = NULL;
553 auth_right.flags = 0;
554
555 auth_rights.count = 1;
556 auth_rights.items = &auth_right;
557
558 auth_flags = kAuthorizationFlagDefaults |
559 kAuthorizationFlagPreAuthorize |
560 kAuthorizationFlagInteractionAllowed |
561 kAuthorizationFlagExtendRights;
562
563 status = AuthorizationCopyRights(http->auth_ref, &auth_rights,
564 kAuthorizationEmptyEnvironment,
565 auth_flags, NULL);
566 if (status == errAuthorizationSuccess)
567 status = AuthorizationMakeExternalForm(http->auth_ref, &auth_extrn);
568
569 if (status == errAuthorizationSuccess)
570 {
571 /*
572 * Set the authorization string and return...
573 */
574
575 httpEncode64_2(buffer, sizeof(buffer), (void *)&auth_extrn,
576 sizeof(auth_extrn));
577
578 httpSetAuthString(http, "AuthRef", buffer);
579
580 DEBUG_printf(("cups_local_auth: Returning authstring = \"%s\"\n",
581 http->authstring));
582 return (0);
583 }
584 else if (status == errAuthorizationCanceled)
585 return (-1);
586
587 DEBUG_printf(("cups_local_auth: AuthorizationCopyRights() returned %d (%s)\n",
588 (int)status, cssmErrorString(status)));
589
590 /*
591 * Fall through to try certificates...
592 */
593 }
594 # endif /* HAVE_AUTHORIZATION_H */
595
596 /*
597 * Try opening a certificate file for this PID. If that fails,
598 * try the root certificate...
599 */
600
601 pid = getpid();
602 snprintf(filename, sizeof(filename), "%s/certs/%d", cg->cups_statedir, pid);
603 if ((fp = fopen(filename, "r")) == NULL && pid > 0)
604 {
605 DEBUG_printf(("cups_local_auth: Unable to open file %s: %s\n",
606 filename, strerror(errno)));
607
608 #ifdef HAVE_GSSAPI
609 /*
610 * If local certificate authentication isn't available for this PID,
611 * check if we need Kerberos authentication...
612 */
613
614 if (!strncmp(http->fields[HTTP_FIELD_WWW_AUTHENTICATE], "Negotiate", 9))
615 {
616 /*
617 * Yes, don't try the root certificate...
618 */
619
620 return (1);
621 }
622 #endif /* HAVE_GSSAPI */
623
624 snprintf(filename, sizeof(filename), "%s/certs/0", cg->cups_statedir);
625 fp = fopen(filename, "r");
626 }
627
628 if (fp)
629 {
630 /*
631 * Read the certificate from the file...
632 */
633
634 fgets(certificate, sizeof(certificate), fp);
635 fclose(fp);
636
637 /*
638 * Set the authorization string and return...
639 */
640
641 httpSetAuthString(http, "Local", certificate);
642
643 DEBUG_printf(("cups_local_auth: Returning authstring = \"%s\"\n",
644 http->authstring));
645
646 return (0);
647 }
648
649 # if defined(SO_PEERCRED) && defined(AF_LOCAL)
650 /*
651 * See if we can authenticate using the peer credentials provided over a
652 * domain socket; if so, specify "PeerCred username" as the authentication
653 * information...
654 */
655
656 if (http->hostaddr->addr.sa_family == AF_LOCAL &&
657 !getenv("GATEWAY_INTERFACE")) /* Not via CGI programs... */
658 {
659 /*
660 * Verify that the current cupsUser() matches the current UID...
661 */
662
663 struct passwd *pwd; /* Password information */
664 const char *username; /* Current username */
665
666 username = cupsUser();
667
668 if ((pwd = getpwnam(username)) != NULL && pwd->pw_uid == getuid())
669 {
670 httpSetAuthString(http, "PeerCred", username);
671
672 DEBUG_printf(("cups_local_auth: Returning authstring = \"%s\"\n",
673 http->authstring));
674
675 return (0);
676 }
677 }
678 # endif /* SO_PEERCRED && AF_LOCAL */
679
680 return (1);
681 #endif /* WIN32 || __EMX__ */
682 }
683
684
685 /*
686 * End of "$Id: auth.c 6779 2007-08-08 19:49:48Z mike $".
687 */