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[doldaconnect.git] / daemon / auth-krb5.c
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d3372da9 1/*
2 * Dolda Connect - Modular multiuser Direct Connect-style client
302a2600 3 * Copyright (C) 2004 Fredrik Tolf <fredrik@dolda2000.com>
d3372da9 4 *
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License as published by
7 * the Free Software Foundation; either version 2 of the License, or
8 * (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
14 *
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
18*/
19
20#include <stdlib.h>
21#include <unistd.h>
22#include <string.h>
23#include <errno.h>
24#include <pwd.h>
25#include <time.h>
26#include <sys/stat.h>
27#include <sys/param.h>
28
29#ifdef HAVE_CONFIG_H
30#include <config.h>
31#endif
32#include "auth.h"
33#include "utils.h"
34#include "conf.h"
35#include "log.h"
36#include "module.h"
37#include "sysevents.h"
38
39#ifdef HAVE_KRB5
40
41#include <krb5.h>
42#include <com_err.h>
43
44struct krb5data
45{
46 int state;
47 krb5_auth_context context;
48 krb5_ticket *ticket;
49 krb5_creds *creds;
50 krb5_ccache ccache;
51 int renew;
52 struct timer *renewtimer;
53 char *username, *cname;
54};
55
56static void setrenew(struct krb5data *data);
57
58static krb5_context k5context;
59static krb5_principal myprinc;
60static krb5_keytab keytab;
61
62static void releasekrb5(struct krb5data *data)
63{
64 if(data->renewtimer != NULL)
65 canceltimer(data->renewtimer);
66 if(data->context != NULL)
67 krb5_auth_con_free(k5context, data->context);
68 if(data->ticket != NULL)
69 krb5_free_ticket(k5context, data->ticket);
70 if(data->creds != NULL)
71 krb5_free_creds(k5context, data->creds);
72 if(data->username != NULL)
73 free(data->username);
74 if(data->cname != NULL)
75 free(data->cname);
76 free(data);
77}
78
79static void release(struct authhandle *auth)
80{
81 releasekrb5((struct krb5data *)auth->mechdata);
82}
83
84static struct krb5data *newkrb5data(void)
85{
86 struct krb5data *new;
87
88 new = smalloc(sizeof(*new));
89 memset(new, 0, sizeof(*new));
90 return(new);
91}
92
93static int inithandle(struct authhandle *auth, char *username)
94{
95 int ret;
96 struct krb5data *data;
97
98 data = newkrb5data();
99 if((ret = krb5_auth_con_init(k5context, &data->context)) != 0)
100 {
101 flog(LOG_ERR, "could initialize Kerberos auth context: %s", error_message(ret));
102 releasekrb5(data);
103 return(1);
104 }
105 krb5_auth_con_setflags(k5context, data->context, KRB5_AUTH_CONTEXT_DO_SEQUENCE);
106 data->username = sstrdup(username);
107 data->state = 0;
108 auth->mechdata = data;
109 return(0);
110}
111
112/* Copied from MIT Kerberos 5 1.3.3*/
113static krb5_boolean my_krb5_kuserok(krb5_context context, krb5_principal principal, const char *luser, const char *loginfile, int authbydef)
114{
115 struct stat sbuf;
116 struct passwd *pwd;
117 char pbuf[MAXPATHLEN];
118 krb5_boolean isok = FALSE;
119 FILE *fp;
120 char kuser[65];
121 char *princname;
122 char linebuf[BUFSIZ];
123 char *newline;
124 int gobble;
125
126 /* no account => no access */
127 if ((pwd = getpwnam(luser)) == NULL) {
128 return(FALSE);
129 }
130 (void) strncpy(pbuf, pwd->pw_dir, sizeof(pbuf) - 1);
131 pbuf[sizeof(pbuf) - 1] = '\0';
132 (void) strncat(pbuf, loginfile, sizeof(pbuf) - 1 - strlen(pbuf));
133
134 if (access(pbuf, F_OK)) { /* not accessible */
135 /*
136 * if he's trying to log in as himself, and there is no .k5login file,
137 * let him. To find out, call
138 * krb5_aname_to_localname to convert the principal to a name
139 * which we can string compare.
140 */
141 if (authbydef) {
142 if (!(krb5_aname_to_localname(context, principal,
143 sizeof(kuser), kuser))
144 && (strcmp(kuser, luser) == 0)) {
145 return(TRUE);
146 }
147 } else {
148 return(FALSE);
149 }
150 }
151 if (krb5_unparse_name(context, principal, &princname))
152 return(FALSE); /* no hope of matching */
153
154 /* open ~/.k5login */
155 if ((fp = fopen(pbuf, "r")) == NULL) {
156 free(princname);
157 return(FALSE);
158 }
159 /*
160 * For security reasons, the .k5login file must be owned either by
161 * the user himself, or by root. Otherwise, don't grant access.
162 */
163 if (fstat(fileno(fp), &sbuf)) {
164 fclose(fp);
165 free(princname);
166 return(FALSE);
167 }
168 if ((sbuf.st_uid != pwd->pw_uid) && sbuf.st_uid) {
169 fclose(fp);
170 free(princname);
171 return(FALSE);
172 }
173
174 /* check each line */
175 while (!isok && (fgets(linebuf, BUFSIZ, fp) != NULL)) {
176 /* null-terminate the input string */
177 linebuf[BUFSIZ-1] = '\0';
178 newline = NULL;
179 /* nuke the newline if it exists */
180 if ((newline = strchr(linebuf, '\n')))
181 *newline = '\0';
182 if (!strcmp(linebuf, princname)) {
183 isok = TRUE;
184 continue;
185 }
186 /* clean up the rest of the line if necessary */
187 if (!newline)
188 while (((gobble = getc(fp)) != EOF) && gobble != '\n');
189 }
190 free(princname);
191 fclose(fp);
192 return(isok);
193}
194
195static void renewcreds(int cancelled, struct krb5data *data)
196{
197 int ret;
198 char ccnambuf[50];
199 krb5_ccache tmpcc;
200 krb5_creds newcreds;
201 static int ccserial = 0;
202
203 data->renewtimer = NULL;
204 if(cancelled)
205 return;
206 memset(&newcreds, 0, sizeof(newcreds));
207 snprintf(ccnambuf, sizeof(ccnambuf), "MEMORY:%i", ccserial++);
208 if((ret = krb5_cc_resolve(k5context, ccnambuf, &tmpcc)) != 0)
209 {
210 flog(LOG_ERR, "could not resolve a temporary ccache `%s': %s", ccnambuf, error_message(ret));
211 data->renew = 0;
212 return;
213 }
214 if((ret = krb5_cc_initialize(k5context, tmpcc, data->ticket->enc_part2->client)) != 0)
215 {
216 flog(LOG_ERR, "could not initialize temporary ccache: %s", error_message(ret));
217 krb5_cc_destroy(k5context, tmpcc);
218 data->renew = 0;
219 return;
220 }
221 if((ret = krb5_cc_store_cred(k5context, tmpcc, data->creds)) != 0)
222 {
223 flog(LOG_ERR, "could not store creds into temporary ccache: %s", error_message(ret));
224 krb5_cc_destroy(k5context, tmpcc);
225 data->renew = 0;
226 return;
227 }
228 if((ret = krb5_get_renewed_creds(k5context, &newcreds, data->ticket->enc_part2->client, tmpcc, NULL)) != 0)
229 {
230 flog(LOG_ERR, "could not get renewed tickets for %s: %s", data->username, error_message(ret));
231 krb5_cc_destroy(k5context, tmpcc);
232 data->renew = 0;
233 return;
234 }
235 krb5_free_creds(k5context, data->creds);
236 data->creds = NULL;
237 if((ret = krb5_copy_creds(k5context, &newcreds, &data->creds)) != 0)
238 {
239 flog(LOG_ERR, "could not copy renewed creds: %s", error_message(ret));
240 krb5_cc_destroy(k5context, tmpcc);
241 data->renew = 0;
242 return;
243 }
244 krb5_free_cred_contents(k5context, &newcreds);
245 krb5_cc_destroy(k5context, tmpcc);
246 flog(LOG_ERR, "successfully renewed krb5 creds for %s", data->username);
247 setrenew(data);
248}
249
250static void setrenew(struct krb5data *data)
251{
252 krb5_ticket_times times;
253 time_t now, good;
254
255 times = data->creds->times;
256 if(!times.starttime)
257 times.starttime = times.authtime;
258 now = time(NULL);
259 if(times.endtime < now)
260 {
261 flog(LOG_DEBUG, "tickets already expired, cannot renew");
262 data->renew = 0;
263 return;
264 }
265 good = times.starttime + (((times.endtime - times.starttime) * 9) / 10);
266 data->renewtimer = timercallback(good, (void (*)(int, void *))renewcreds, data);
267}
268
3616b334 269static int krbauth(struct authhandle *auth, struct socket *sk, char *passdata)
d3372da9 270{
271 int ret;
272 struct krb5data *data;
273 char *msg;
274 size_t msglen;
275 int authorized;
276 krb5_data k5d;
277 krb5_flags apopt;
278 krb5_creds **fwdcreds;
279
280 data = auth->mechdata;
281 if(passdata == NULL)
282 {
283 auth->prompt = AUTH_PR_AUTO;
284 if(auth->text != NULL)
285 free(auth->text);
286 auth->text = swcsdup(L"Send hex-encoded krb5 data");
287 data->state = 1;
288 return(AUTH_PASS);
289 } else {
290 if((msg = hexdecode(passdata, &msglen)) == NULL)
291 {
292 if(auth->text != NULL)
293 free(auth->text);
294 auth->text = swcsdup(L"Invalid hex encoding");
295 return(AUTH_DENIED);
296 }
297 switch(data->state)
298 {
299 case 1:
300 k5d.length = msglen;
301 k5d.data = msg;
302 if((ret = krb5_rd_req(k5context, &data->context, &k5d, myprinc, keytab, &apopt, &data->ticket)) != 0)
303 {
304 flog(LOG_INFO, "kerberos authentication failed for %s: %s", data->username, error_message(ret));
305 if(auth->text != NULL)
306 free(auth->text);
307 auth->text = icmbstowcs((char *)error_message(ret), NULL);
1b4e77a0 308 free(msg);
d3372da9 309 return(AUTH_DENIED);
310 }
311 free(msg);
312 if(apopt & AP_OPTS_MUTUAL_REQUIRED)
313 {
314 if((ret = krb5_mk_rep(k5context, data->context, &k5d)) != 0)
315 {
316 flog(LOG_WARNING, "krb5_mk_rep returned an error: %s", error_message(ret));
317 return(AUTH_ERR);
318 }
319 msg = hexencode(k5d.data, k5d.length);
320 if(auth->text != NULL)
321 free(auth->text);
322 auth->text = icmbstowcs(msg, "us-ascii");
323 free(msg);
324 free(k5d.data);
325 } else {
326 if(auth->text != NULL)
327 free(auth->text);
328 auth->text = swcsdup(L"");
329 }
330 data->state = 2;
331 return(AUTH_PASS);
332 case 2:
333 ret = atoi(msg);
334 free(msg);
335 if(ret == 1)
336 {
337 /* That is, the client has accepted us as a valid
338 * server. Now check if the client is authorized. */
339 if((ret = krb5_unparse_name(k5context, data->ticket->enc_part2->client, &data->cname)) != 0)
340 {
341 flog(LOG_ERR, "krb_unparse_name returned an error: %s", error_message(ret));
342 return(AUTH_ERR);
343 }
344 authorized = 0;
345 if(!authorized && my_krb5_kuserok(k5context, data->ticket->enc_part2->client, data->username, "/.k5login", 1))
346 authorized = 1;
347 /* Allow a seperate ACL for DC principals */
348 if(!authorized && my_krb5_kuserok(k5context, data->ticket->enc_part2->client, data->username, "/.dc-k5login", 0))
349 authorized = 1;
350 if(authorized)
351 {
d1a6180d 352 flog(LOG_INFO, "krb5 principal %s successfully authorized as %s%s", data->cname, data->username, (data->creds == NULL)?"":" (with fwd creds)");
d3372da9 353 return(AUTH_SUCCESS);
354 } else {
355 flog(LOG_INFO, "krb5 principal %s not authorized as %s", data->cname, data->username);
356 }
357 }
358 if(ret == 2)
359 {
360 if(auth->text != NULL)
361 free(auth->text);
362 auth->text = swcsdup(L"");
363 data->state = 3;
364 return(AUTH_PASS);
365 }
366 return(AUTH_DENIED);
367 case 3:
368 k5d.length = msglen;
369 k5d.data = msg;
370 if((ret = krb5_rd_cred(k5context, data->context, &k5d, &fwdcreds, NULL)) != 0)
371 {
372 flog(LOG_ERR, "krb5_rd_cred returned an error: %s", error_message(ret));
1b4e77a0 373 free(msg);
d3372da9 374 return(AUTH_ERR);
375 }
1b4e77a0 376 free(msg);
d3372da9 377 if(*fwdcreds == NULL)
378 {
379 flog(LOG_ERR, "forwarded credentials array was empty (from %s)", data->username);
380 krb5_free_tgt_creds(k5context, fwdcreds);
381 return(AUTH_ERR);
382 }
d3372da9 383 /* Copy only the first credential. (Change this if it becomes a problem) */
384 ret = krb5_copy_creds(k5context, *fwdcreds, &data->creds);
385 krb5_free_tgt_creds(k5context, fwdcreds);
386 if(ret != 0)
387 {
388 flog(LOG_ERR, "could not copy forwarded credentials: %s", error_message(ret));
389 return(AUTH_ERR);
390 }
391 if(confgetint("auth-krb5", "renewcreds"))
392 {
393 data->renew = 1;
394 setrenew(data);
395 }
396 if(auth->text != NULL)
397 free(auth->text);
398 auth->text = swcsdup(L"");
399 data->state = 2;
400 return(AUTH_PASS);
401 default:
402 free(msg);
403 flog(LOG_ERR, "BUG? Invalid state encountered in krbauth: %i", data->state);
404 return(AUTH_ERR);
405 }
406 }
407}
408
409static int opensess(struct authhandle *auth)
410{
411 int ret;
412 struct krb5data *data;
413 char *buf, *buf2;
414 int fd;
415 struct passwd *pwent;
416
417 data = auth->mechdata;
418 if(data->creds != NULL)
419 {
420 if((pwent = getpwnam(data->username)) == NULL)
421 {
422 flog(LOG_ERR, "could not get passwd entry for forwarded tickets (user %s): %s", data->username, strerror(errno));
423 return(AUTH_ERR);
424 }
5f462292 425 if(!confgetint("auth-krb5", "usedefcc"))
d3372da9 426 {
56838143 427 buf = sprintf2("/tmp/krb5cc_dc_%i_XXXXXX", pwent->pw_uid);
428 if((fd = mkstemp(buf)) < 0)
429 {
430 free(buf);
431 flog(LOG_ERR, "could not create temporary file for ccache: %s", strerror(errno));
432 return(AUTH_ERR);
433 }
434 close(fd);
435 buf2 = sprintf2("FILE:%s", buf);
436 if((ret = krb5_cc_resolve(k5context, buf2, &data->ccache)) != 0)
437 {
438 free(buf);
439 free(buf2);
440 flog(LOG_ERR, "could not resolve ccache name \"%s\": %s", buf2, error_message(ret));
441 return(AUTH_ERR);
442 }
443 setenv("KRB5CCNAME", buf2, 1);
d3372da9 444 free(buf2);
56838143 445 if((ret = krb5_cc_initialize(k5context, data->ccache, data->ticket->enc_part2->client)) != 0)
446 {
447 free(buf);
448 flog(LOG_ERR, "could not initialize ccache: %s", error_message(ret));
449 return(AUTH_ERR);
450 }
451 if((ret = krb5_cc_store_cred(k5context, data->ccache, data->creds)) != 0)
452 {
453 free(buf);
454 flog(LOG_ERR, "could not store forwarded TGT into ccache: %s", error_message(ret));
455 return(AUTH_ERR);
456 }
457 if(chown(buf, pwent->pw_uid, pwent->pw_gid))
458 {
459 free(buf);
460 flog(LOG_ERR, "could not chown new ccache to %i:%i: %s", pwent->pw_uid, pwent->pw_gid, strerror(errno));
461 return(AUTH_ERR);
462 }
d3372da9 463 free(buf);
56838143 464 } else {
d2a3e34a 465 if((buf = (char *)krb5_cc_default_name(k5context)) == NULL) {
56838143 466 flog(LOG_ERR, "could not get default ccache name");
467 return(AUTH_ERR);
468 }
469 if((ret = krb5_cc_resolve(k5context, buf, &data->ccache)) != 0)
470 {
70d8f2f1 471 flog(LOG_ERR, "could not resolve ccache name \"%s\": %s", buf, error_message(ret));
56838143 472 return(AUTH_ERR);
473 }
474 setenv("KRB5CCNAME", buf, 1);
475 if((ret = krb5_cc_initialize(k5context, data->ccache, data->ticket->enc_part2->client)) != 0)
476 {
477 flog(LOG_ERR, "could not initialize ccache: %s", error_message(ret));
478 return(AUTH_ERR);
479 }
480 if((ret = krb5_cc_store_cred(k5context, data->ccache, data->creds)) != 0)
481 {
482 flog(LOG_ERR, "could not store forwarded TGT into ccache: %s", error_message(ret));
483 return(AUTH_ERR);
484 }
d3372da9 485 }
d3372da9 486 }
487 return(AUTH_SUCCESS);
488}
489
490static int closesess(struct authhandle *auth)
491{
492 struct krb5data *data;
493
494 data = auth->mechdata;
495 if(data->ccache != NULL)
496 {
497 krb5_cc_destroy(k5context, data->ccache);
498 data->ccache = NULL;
499 }
500 return(AUTH_SUCCESS);
501}
502
503struct authmech authmech_krb5 =
504{
505 .inithandle = inithandle,
506 .release = release,
507 .authenticate = krbauth,
508 .opensess = opensess,
509 .closesess = closesess,
510 .name = L"krb5",
511 .enabled = 1
512};
513
514static int init(int hup)
515{
516 int ret;
517 char *buf;
518 krb5_principal newprinc;
519
520 if(!hup)
521 {
522 regmech(&authmech_krb5);
523 if((ret = krb5_init_context(&k5context)))
524 {
525 flog(LOG_CRIT, "could not initialize Kerberos context: %s", error_message(ret));
526 return(1);
527 }
528 if((buf = icwcstombs(confgetstr("auth-krb5", "service"), NULL)) == NULL)
529 {
530 flog(LOG_CRIT, "could not convert service name (%ls) into local charset: %s", confgetstr("auth-krb5", "service"), strerror(errno));
531 return(1);
532 } else {
533 if((ret = krb5_sname_to_principal(k5context, NULL, buf, KRB5_NT_SRV_HST, &myprinc)) != 0)
534 {
535 flog(LOG_CRIT, "could not get principal for service %s: %s", buf, error_message(ret));
536 free(buf);
537 return(1);
538 }
539 free(buf);
540 }
541 if((buf = icwcstombs(confgetstr("auth-krb5", "keytab"), NULL)) == NULL)
542 {
543 flog(LOG_ERR, "could not convert keytab name (%ls) into local charset: %s, using default keytab instead", confgetstr("auth-krb5", "keytab"), strerror(errno));
544 keytab = NULL;
545 } else {
546 if((ret = krb5_kt_resolve(k5context, buf, &keytab)) != 0)
547 {
548 flog(LOG_ERR, "could not open keytab %s: %s, using default keytab instead", buf, error_message(ret));
549 keytab = NULL;
550 }
551 free(buf);
552 }
553 }
554 if(hup)
555 {
556 if((buf = icwcstombs(confgetstr("auth-krb5", "service"), NULL)) == NULL)
557 {
558 flog(LOG_CRIT, "could not convert service name (%ls) into local charset: %s, not updating principal", confgetstr("auth-krb5", "service"), strerror(errno));
559 } else {
560 if((ret = krb5_sname_to_principal(k5context, NULL, buf, KRB5_NT_SRV_HST, &newprinc)) != 0)
561 {
562 flog(LOG_CRIT, "could not get principal for service %s: %s, not updating principal", buf, error_message(ret));
563 } else {
564 krb5_free_principal(k5context, myprinc);
565 myprinc = newprinc;
566 }
567 free(buf);
568 }
569 if(keytab != NULL)
570 krb5_kt_close(k5context, keytab);
571 if((buf = icwcstombs(confgetstr("auth-krb5", "keytab"), NULL)) == NULL)
572 {
573 flog(LOG_ERR, "could not convert keytab name (%ls) into local charset: %s, using default keytab instead", confgetstr("auth-krb5", "keytab"), strerror(errno));
574 keytab = NULL;
575 } else {
576 if((ret = krb5_kt_resolve(k5context, buf, &keytab)) != 0)
577 {
578 flog(LOG_ERR, "could not open keytab %s: %s, using default keytab instead", buf, error_message(ret));
579 keytab = NULL;
580 }
581 free(buf);
582 }
583 }
584 return(0);
585}
586
587static void terminate(void)
588{
589 if(keytab != NULL)
590 krb5_kt_close(k5context, keytab);
591 krb5_free_principal(k5context, myprinc);
592 krb5_free_context(k5context);
593}
594
595static struct configvar myvars[] =
596{
0ecdd176 597 /** The name of the service principal to use for Kerberos V
598 * authentication. */
d3372da9 599 {CONF_VAR_STRING, "service", {.str = L"doldacond"}},
d9f89ef5 600 /** The path to an alternative keytab file. If unspecified, the
601 * system default keytab will be used. */
d3372da9 602 {CONF_VAR_STRING, "keytab", {.str = L""}},
d9f89ef5 603 /** Whether to renew renewable credentials automatically before
604 * they expire. */
d3372da9 605 {CONF_VAR_BOOL, "renewcreds", {.num = 1}},
d9f89ef5 606 /** If true, the default credentials cache will be used, which is
607 * useful for e.g. Linux kernel key handling. If false, a file
608 * credentials cache will be created using mkstemp(3), using the
609 * pattern /tmp/krb5cc_dc_$UID_XXXXXX. */
56838143 610 {CONF_VAR_BOOL, "usedefcc", {.num = 0}},
d3372da9 611 {CONF_VAR_END}
612};
613
614static struct module me =
615{
616 .conf =
617 {
618 .vars = myvars
619 },
620 .init = init,
621 .terminate = terminate,
622 .name = "auth-krb5"
623};
624
625MODULE(me);
626
627#endif /* HAVE_KRB5 */