File: auth_krb5.c

package info (click to toggle)
cyrus-sasl2 2.1.27+dfsg-1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye, buster, sid
  • size: 19,700 kB
  • sloc: ansic: 58,924; sh: 4,843; java: 1,614; xml: 1,498; makefile: 1,265; python: 350; perl: 199
file content (483 lines) | stat: -rw-r--r-- 13,856 bytes parent folder | download
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
/* MODULE: auth_krb5 */

/* COPYRIGHT
 * Copyright (c) 1997 Messaging Direct Ltd.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY MESSAGING DIRECT LTD. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL MESSAGING DIRECT LTD. OR
 * ITS EMPLOYEES OR AGENTS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR
 * TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 * END COPYRIGHT */

/* ok, this is  wrong but the most convenient way of doing 
 * it for now. We assume (possibly incorrectly) that if GSSAPI exists then 
 * the Kerberos 5 headers and libraries exist.   
 * What really should be done is a configure.in check for krb5.h and use 
 * that since none of this code is GSSAPI but rather raw Kerberos5.
 */


/* Also, at some point one would hope it would be possible to
 * have less divergence between Heimdal and MIT Kerberos 5.
 *
 * As of the summer of 2003, the obvious issues are that
 * MIT doesn't have krb5_verify_opt_*() and Heimdal doesn't
 * have krb5_sname_to_principal().
 */

/* PUBLIC DEPENDENCIES */
#include "mechanisms.h"
#include "globals.h" /* mech_option */
#include "cfile.h"
#include "krbtf.h"

#ifdef AUTH_KRB5
# include <krb5.h>
static cfile config = 0;
static char *keytabname = NULL; /* "system default" */
static char *verify_principal = "host"; /* a principal in the default keytab */
#endif /* AUTH_KRB5 */

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>
#include <sys/stat.h>
#include "auth_krb5.h"

/* END PUBLIC DEPENDENCIES */

int					/* R: -1 on failure, else 0 */
auth_krb5_init (
  /* PARAMETERS */
  void					/* no parameters */
  /* END PARAMETERS */
  )
{
#ifdef AUTH_KRB5
    char *configname = 0;

    if (krbtf_init() == -1) {
	syslog(LOG_ERR, "auth_krb5_init krbtf_init failed");
	return -1;
    }

    if (mech_option)
	configname = mech_option;
    else if (access(SASLAUTHD_CONF_FILE_DEFAULT, F_OK) == 0)
	configname = SASLAUTHD_CONF_FILE_DEFAULT;
 
    if (configname) {
	char complaint[1024];

	if (!(config = cfile_read(configname, complaint, sizeof (complaint)))) {
	    syslog(LOG_ERR, "auth_krb5_init %s", complaint);
	    return -1;
	}
    }

    if (config) {
	keytabname = (char *) cfile_getstring(config, "krb5_keytab", keytabname);
	verify_principal = (char *) cfile_getstring(config, "krb5_verify_principal", verify_principal);
    }

    return 0;

#else
    return -1;
#endif
}

#ifdef AUTH_KRB5

static int
form_principal_name (
  const char *user,
  const char *service,
  const char *realm,
  char *pname,
  int pnamelen
  )
{
    const char *forced_instance = 0;
	int plen;

    plen = strlcpy(pname, user, pnamelen);
    user = pname;

    if (config && cfile_getswitch(config, "krb5_conv_krb4_instance", 0)) {
       char *krb4_instance;

       if ((krb4_instance = strchr(pname, '.'))) *krb4_instance = '/';
    }

    if (config) {
	char keyname[1024];

	snprintf(keyname, sizeof (keyname), "krb5_%s_instance", service);
	forced_instance = cfile_getstring(config, keyname, 0);
    }

    if (forced_instance) {
	char *user_specified;

	if ((user_specified = strchr(user, '/'))) {
	    if (strcmp(user_specified + 1, forced_instance)) {
		/* user not allowed to override sysadmin */
		return -1;
	    } else {
		/* don't need to force--user already asked for it */
		forced_instance = 0;
	    }
	}
    }

    /* form user[/instance][@realm] */
    plen += snprintf(pname+plen, pnamelen-plen, "%s%s%s%s",
	(forced_instance ? "/" : ""),
	(forced_instance ? forced_instance : ""),
	((realm && realm[0]) ? "@" : ""),
	((realm && realm[0]) ? realm : "")
	);
    if ((plen <= 0) || (plen >= pnamelen))
	return -1;

    /* Perhaps we should uppercase the realm? */

    return 0;
}

#ifdef KRB5_HEIMDAL

char *					/* R: allocated response string */
auth_krb5 (
  /* PARAMETERS */
  const char *user,			/* I: plaintext authenticator */
  const char *password,			/* I: plaintext password */
  const char *service,                  /* I: service authenticating to */
  const char *realm                     /* I: user's realm */
  /* END PARAMETERS */
  )
{
    /* VARIABLES */
    krb5_context context;
    krb5_ccache ccache = NULL;
    krb5_keytab kt = NULL;
    krb5_principal auth_user;
    krb5_verify_opt opt;
    char * result;
    char tfname[2048];
    char principalbuf[2048];
    /* END VARIABLES */

    if (!user || !password) {
	syslog(LOG_ERR, "auth_krb5: NULL password or username?");
	return strdup("NO saslauthd internal NULL password or username");
    }

    if (krb5_init_context(&context)) {
	syslog(LOG_ERR, "auth_krb5: krb5_init_context");
	return strdup("NO saslauthd internal krb5_init_context error");
    }

    if (form_principal_name(user, service, realm, principalbuf, sizeof (principalbuf))) {
	syslog(LOG_ERR, "auth_krb5: form_principal_name");
	return strdup("NO saslauthd principal name error");
    }

    if (krb5_parse_name (context, principalbuf, &auth_user)) {
	krb5_free_context(context);
	syslog(LOG_ERR, "auth_krb5: krb5_parse_name");
	return strdup("NO saslauthd internal krb5_parse_name error");
    }

    if (krbtf_name(tfname, sizeof (tfname)) != 0) {
	syslog(LOG_ERR, "auth_krb5: could not generate ccache name");
	return strdup("NO saslauthd internal error");
    }

    if (krb5_cc_resolve(context, tfname, &ccache)) {
	krb5_free_principal(context, auth_user);
	krb5_free_context(context);
	syslog(LOG_ERR, "auth_krb5: krb5_cc_resolve");
	return strdup("NO saslauthd internal error");
    }

    if (keytabname) {
	if (krb5_kt_resolve(context, keytabname, &kt)) {
	    krb5_free_principal(context, auth_user);
	    krb5_cc_destroy(context, ccache);
	    krb5_free_context(context);
	    syslog(LOG_ERR, "auth_krb5: krb5_kt_resolve");
	    return strdup("NO saslauthd internal error");
	}
    }
    
    krb5_verify_opt_init(&opt);
    krb5_verify_opt_set_secure(&opt, 1);
    krb5_verify_opt_set_ccache(&opt, ccache);
    if (kt)
	krb5_verify_opt_set_keytab(&opt,  kt);
    krb5_verify_opt_set_service(&opt, verify_principal);
    
    if (krb5_verify_user_opt(context, auth_user, password, &opt)) {
	result = strdup("NO krb5_verify_user_opt failed");
    } else {
        result = strdup("OK");
    }
    
    krb5_free_principal(context, auth_user);
    krb5_cc_destroy(context, ccache);
    if (kt)
	krb5_kt_close(context, kt);
    krb5_free_context(context);

    return result;
}

#else /* !KRB5_HEIMDAL */

static void k5support_log_err(int priority,
                              krb5_context context,
			      krb5_error_code code,
			      char const *msg)
{
    const char *k5_msg = krb5_get_error_message(context, code);

    syslog(priority, "auth_krb5: %s: %s (%d)\n", msg, k5_msg, code);
    krb5_free_error_message(context, k5_msg);
}

/* returns 0 for failure, 1 for success */
static int k5support_verify_tgt(krb5_context context, 
				krb5_ccache ccache) 
{
    krb5_principal server;
    krb5_data packet;
    krb5_keyblock *keyblock = NULL;
    krb5_auth_context auth_context = NULL;
    krb5_error_code k5_retcode;
    krb5_keytab kt = NULL;
    char thishost[BUFSIZ];
    int result = 0;
    
    memset(&packet, 0, sizeof(packet));

    if ((k5_retcode = krb5_sname_to_principal(context, NULL, verify_principal,
					      KRB5_NT_SRV_HST, &server))) {
	k5support_log_err(LOG_DEBUG, context, k5_retcode, "krb5_sname_to_principal()");
	return 0;
    }

    if (keytabname) {
	if ((k5_retcode = krb5_kt_resolve(context, keytabname, &kt))) {
	    k5support_log_err(LOG_DEBUG, context, k5_retcode, "krb5_kt_resolve()");
	    goto fini;
	}
    }
    
    if ((k5_retcode = krb5_kt_read_service_key(context, kt, server, 0,
					       0, &keyblock))) {
	k5support_log_err(LOG_DEBUG, context, k5_retcode, "krb5_kt_read_service_key()");
	goto fini;
    }
    
    if (keyblock) {
	krb5_free_keyblock(context, keyblock);
    }
    
    /* this duplicates work done in krb5_sname_to_principal
     * oh well.
     */
    if (gethostname(thishost, BUFSIZ) < 0) {
	goto fini;
    }
    thishost[BUFSIZ-1] = '\0';
    
    if ((k5_retcode = krb5_mk_req(context, &auth_context, 0, verify_principal, 
				  thishost, NULL, ccache, &packet))) {
	k5support_log_err(LOG_DEBUG, context, k5_retcode, "krb5_mk_req()");
    }
    
    if (auth_context) {
	krb5_auth_con_free(context, auth_context);
	auth_context = NULL;
    }
    
    if (k5_retcode) {
	goto fini;
    }
    
    if ((k5_retcode = krb5_rd_req(context, &auth_context, &packet, 
				  server, NULL, NULL, NULL))) {
	k5support_log_err(LOG_DEBUG, context, k5_retcode, "krb5_rd_req()");
	goto fini;
    }

    if (auth_context) {
      krb5_auth_con_free(context, auth_context);
      auth_context = NULL;
    }
    
    /* all is good now */
    result = 1;
 fini:
    if (!k5_retcode) {
        krb5_free_data_contents(context, &packet);
    }
    krb5_free_principal(context, server);
    
    return result;
}

/* FUNCTION: auth_krb5 */

/* SYNOPSIS
 * Authenticate against Kerberos V.
 * END SYNOPSIS */

char *					/* R: allocated response string */
auth_krb5 (
  /* PARAMETERS */
  const char *user,			/* I: plaintext authenticator */
  const char *password,			/* I: plaintext password */
  const char *service,			/* I: service authenticating to */
  const char *realm			/* I: user's realm */
  /* END PARAMETERS */
  )
{
    /* VARIABLES */
    krb5_context context;
    krb5_ccache ccache = NULL;
    krb5_principal auth_user;
    krb5_creds creds;
    krb5_get_init_creds_opt opts;
    char * result;
    char tfname[2048];
    char principalbuf[2048];
    krb5_error_code code;
    /* END VARIABLES */

    if (!user|| !password) {
	syslog(LOG_ERR, "auth_krb5: NULL password or username?");
	return strdup("NO saslauthd internal error");
    }

    if (krb5_init_context(&context)) {
	syslog(LOG_ERR, "auth_krb5: krb5_init_context");
	return strdup("NO saslauthd internal error");
    }

    if (form_principal_name(user, service, realm, principalbuf, sizeof (principalbuf))) {
	syslog(LOG_ERR, "auth_krb5: form_principal_name");
	return strdup("NO saslauthd principal name error");
    }

    if ((code = krb5_parse_name (context, principalbuf, &auth_user))) {
	k5support_log_err(LOG_ERR, context, code, "krb5_parse_name()");
	krb5_free_context(context);
	return strdup("NO saslauthd internal error");
    }
    
    if (krbtf_name(tfname, sizeof (tfname)) != 0) {
	syslog(LOG_ERR, "auth_krb5: could not generate ticket file name");
	return strdup("NO saslauthd internal error");
    }

    if ((code = krb5_cc_resolve(context, tfname, &ccache))) {
	k5support_log_err(LOG_ERR, context, code, "krb5_cc_resolve()");
	krb5_free_principal(context, auth_user);
	krb5_free_context(context);
	return strdup("NO saslauthd internal error");
    }
    
    if ((code = krb5_cc_initialize (context, ccache, auth_user))) {
	k5support_log_err(LOG_ERR, context, code, "krb5_cc_initialize()");
	krb5_free_principal(context, auth_user);
	krb5_free_context(context);
	return strdup("NO saslauthd internal error");
    }
    
    krb5_get_init_creds_opt_init(&opts);
    /* 15 min should be more than enough */
    krb5_get_init_creds_opt_set_tkt_life(&opts, 900); 
    if ((code = krb5_get_init_creds_password(context, &creds, 
                                             auth_user, password, NULL, NULL, 
                                             0, NULL, &opts))) {
	k5support_log_err(LOG_ERR, context, code, "krb5_get_init_creds_password()");
	krb5_cc_destroy(context, ccache);
	krb5_free_principal(context, auth_user);
	krb5_free_context(context);
	return strdup("NO saslauthd internal error");
    }
    
    /* at this point we should have a TGT. Let's make sure it is valid */
    if ((code = krb5_cc_store_cred(context, ccache, &creds))) {
	k5support_log_err(LOG_ERR, context, code, "krb5_cc_store_cred()");
	krb5_free_principal(context, auth_user);
	krb5_cc_destroy(context, ccache);
	krb5_free_context(context);
	return strdup("NO saslauthd internal error");
    }
    
    if (!k5support_verify_tgt(context, ccache)) {
	syslog(LOG_ERR, "auth_krb5: k5support_verify_tgt");
	result = strdup("NO saslauthd internal error");
	goto fini;
    }
    
    /* 
     * fall through -- user is valid beyond this point  
     */
    
    result = strdup("OK");
 fini:
/* destroy any tickets we had */
    krb5_free_cred_contents(context, &creds);
    krb5_free_principal(context, auth_user);
    krb5_cc_destroy(context, ccache);
    krb5_free_context(context);

    return result;
}

#endif /* KRB5_HEIMDAL */

#else /* ! AUTH_KRB5 */

char *
auth_krb5 (
  const char *login __attribute__((unused)),
  const char *password __attribute__((unused)),
  const char *service __attribute__((unused)),
  const char *realm __attribute__((unused))
  )
{
    return NULL;
}

#endif /* ! AUTH_KRB5 */

/* END FUNCTION: auth_krb5 */

/* END MODULE: auth_krb5 */