1 /* $OpenBSD: authenticate.c,v 1.29 2021/10/24 21:24:20 deraadt Exp $ */
2
3 /*-
4 * Copyright (c) 1997 Berkeley Software Design, Inc. All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. All advertising materials mentioning features or use of this software
15 * must display the following acknowledgement:
16 * This product includes software developed by Berkeley Software Design,
17 * Inc.
18 * 4. The name of Berkeley Software Design, Inc. may not be used to endorse
19 * or promote products derived from this software without specific prior
20 * written permission.
21 *
22 * THIS SOFTWARE IS PROVIDED BY BERKELEY SOFTWARE DESIGN, INC. ``AS IS'' AND
23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
25 * ARE DISCLAIMED. IN NO EVENT SHALL BERKELEY SOFTWARE DESIGN, INC. BE LIABLE
26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
32 * SUCH DAMAGE.
33 *
34 * BSDI $From: authenticate.c,v 2.21 1999/09/08 22:33:26 prb Exp $
35 */
36
37 #include <sys/stat.h>
38
39 #include <ctype.h>
40 #include <err.h>
41 #include <fcntl.h>
42 #include <limits.h>
43 #include <login_cap.h>
44 #include <paths.h>
45 #include <pwd.h>
46 #include <stdarg.h>
47 #include <stdio.h>
48 #include <stdlib.h>
49 #include <string.h>
50 #include <syslog.h>
51 #include <unistd.h>
52
53 #include <bsd_auth.h>
54
55 static int _auth_checknologin(login_cap_t *, int);
56
57 char *
auth_mkvalue(char * value)58 auth_mkvalue(char *value)
59 {
60 char *big, *p;
61
62 big = malloc(strlen(value) * 4 + 1);
63 if (big == NULL)
64 return (NULL);
65 /*
66 * XXX - There should be a more standardized
67 * routine for doing this sort of thing.
68 */
69 for (p = big; *value; ++value) {
70 switch (*value) {
71 case '\r':
72 *p++ = '\\';
73 *p++ = 'r';
74 break;
75 case '\n':
76 *p++ = '\\';
77 *p++ = 'n';
78 break;
79 case '\\':
80 *p++ = '\\';
81 *p++ = *value;
82 break;
83 case '\t':
84 case ' ':
85 if (p == big)
86 *p++ = '\\';
87 *p++ = *value;
88 break;
89 default:
90 if (!isprint((unsigned char)*value)) {
91 *p++ = '\\';
92 *p++ = ((*value >> 6) & 0x3) + '0';
93 *p++ = ((*value >> 3) & 0x7) + '0';
94 *p++ = ((*value ) & 0x7) + '0';
95 } else
96 *p++ = *value;
97 break;
98 }
99 }
100 *p = '\0';
101 return (big);
102 }
103 DEF_WEAK(auth_mkvalue);
104
105 void
auth_checknologin(login_cap_t * lc)106 auth_checknologin(login_cap_t *lc)
107 {
108 if (_auth_checknologin(lc, 1))
109 exit(1);
110 }
111 DEF_WEAK(auth_checknologin);
112
113 static int
_auth_checknologin(login_cap_t * lc,int print)114 _auth_checknologin(login_cap_t *lc, int print)
115 {
116 struct stat sb;
117 char *nologin;
118 int mustfree;
119
120 if (login_getcapbool(lc, "ignorenologin", 0))
121 return (0);
122
123 /*
124 * If we fail to get the nologin file due to a database error,
125 * assume there should have been one...
126 */
127 nologin = login_getcapstr(lc, "nologin", "", NULL);
128 mustfree = nologin && *nologin != '\0';
129 if (nologin == NULL)
130 goto print_nologin;
131
132 /* First try the nologin file specified in login.conf. */
133 if (*nologin != '\0' && stat(nologin, &sb) == 0)
134 goto print_nologin;
135 if (mustfree) {
136 free(nologin);
137 mustfree = 0;
138 }
139
140 /* If that doesn't exist try _PATH_NOLOGIN. */
141 if (stat(_PATH_NOLOGIN, &sb) == 0) {
142 nologin = _PATH_NOLOGIN;
143 goto print_nologin;
144 }
145
146 /* Couldn't stat any nologin files, must be OK to login. */
147 return (0);
148
149 print_nologin:
150 if (print) {
151 if (!nologin || *nologin == '\0' || auth_cat(nologin) == 0) {
152 puts("Logins are not allowed at this time.");
153 fflush(stdout);
154 }
155 }
156 if (mustfree)
157 free(nologin);
158 return (-1);
159 }
160
161 int
auth_cat(char * file)162 auth_cat(char *file)
163 {
164 int fd, nchars;
165 char tbuf[8192];
166
167 if ((fd = open(file, O_RDONLY)) == -1)
168 return (0);
169 while ((nchars = read(fd, tbuf, sizeof(tbuf))) > 0)
170 (void)write(fileno(stdout), tbuf, nchars);
171 (void)close(fd);
172 return (1);
173 }
174 DEF_WEAK(auth_cat);
175
176 int
_auth_validuser(const char * name)177 _auth_validuser(const char *name)
178 {
179 /* User name must be specified and may not start with a '-'. */
180 if (*name == '\0' || *name == '-') {
181 syslog(LOG_ERR, "invalid user name %s", name);
182 return 0;
183 }
184 return 1;
185 }
186
187 int
auth_approval(auth_session_t * as,login_cap_t * lc,char * name,char * type)188 auth_approval(auth_session_t *as, login_cap_t *lc, char *name, char *type)
189 {
190 int close_on_exit, close_lc_on_exit, len;
191 struct passwd pwstore, *pwd;
192 char *approve, *s, path[PATH_MAX], pwbuf[_PW_BUF_LEN];
193
194 pwd = NULL;
195 close_on_exit = as == NULL;
196 close_lc_on_exit = lc == NULL;
197
198 if (as != NULL && name == NULL)
199 name = auth_getitem(as, AUTHV_NAME);
200
201 if (as != NULL)
202 pwd = auth_getpwd(as);
203
204 if (pwd == NULL) {
205 if (name != NULL) {
206 if (!_auth_validuser(name)) {
207 warnx("cannot approve who we don't recognize");
208 return (0);
209 }
210 getpwnam_r(name, &pwstore, pwbuf, sizeof(pwbuf), &pwd);
211 } else {
212 getpwuid_r(getuid(), &pwstore, pwbuf, sizeof(pwbuf),
213 &pwd);
214 if (pwd == NULL) {
215 syslog(LOG_ERR, "no such user id %u", getuid());
216 warnx("cannot approve who we don't recognize");
217 return (0);
218 }
219 name = pwd->pw_name;
220 }
221 }
222
223 if (name == NULL)
224 name = pwd->pw_name;
225
226 if (lc == NULL) {
227 if (strlen(name) >= PATH_MAX) {
228 syslog(LOG_ERR, "username to login %.*s...",
229 PATH_MAX, name);
230 warnx("username too long");
231 return (0);
232 }
233 if (pwd == NULL && (approve = strchr(name, '.')) != NULL) {
234 strlcpy(path, name, sizeof path);
235 path[approve - name] = '\0';
236 getpwnam_r(name, &pwstore, pwbuf, sizeof(pwbuf), &pwd);
237 }
238 lc = login_getclass(pwd ? pwd->pw_class : NULL);
239 if (lc == NULL) {
240 warnx("unable to classify user");
241 return (0);
242 }
243 }
244
245 if (!type)
246 type = LOGIN_DEFSERVICE;
247 else {
248 if (strncmp(type, "approve-", 8) == 0)
249 type += 8;
250
251 len = snprintf(path, sizeof(path), "approve-%s", type);
252 if (len < 0 || len >= sizeof(path)) {
253 if (close_lc_on_exit)
254 login_close(lc);
255 syslog(LOG_ERR, "approval path too long %.*s...",
256 PATH_MAX, type);
257 warnx("approval script path too long");
258 return (0);
259 }
260 }
261
262 if ((approve = login_getcapstr(lc, s = path, NULL, NULL)) == NULL)
263 approve = login_getcapstr(lc, s = "approve", NULL, NULL);
264
265 if (approve && approve[0] != '/') {
266 if (close_lc_on_exit)
267 login_close(lc);
268 syslog(LOG_ERR, "Invalid %s script: %s", s, approve);
269 warnx("invalid path to approval script");
270 free(approve);
271 return (0);
272 }
273
274 if (as == NULL && (as = auth_open()) == NULL) {
275 if (close_lc_on_exit)
276 login_close(lc);
277 syslog(LOG_ERR, "%m");
278 warn(NULL);
279 free(approve);
280 return (0);
281 }
282
283 auth_setstate(as, AUTH_OKAY);
284 if (auth_setitem(as, AUTHV_NAME, name) < 0) {
285 syslog(LOG_ERR, "%m");
286 warn(NULL);
287 goto out;
288 }
289 if (auth_check_expire(as) < 0) /* is this account expired */
290 goto out;
291 if (_auth_checknologin(lc,
292 auth_getitem(as, AUTHV_INTERACTIVE) != NULL)) {
293 auth_setstate(as, (auth_getstate(as) & ~AUTH_ALLOW));
294 goto out;
295 }
296 if (login_getcapbool(lc, "requirehome", 0) && pwd && pwd->pw_dir &&
297 pwd->pw_dir[0]) {
298 struct stat sb;
299
300 if (stat(pwd->pw_dir, &sb) == -1 || !S_ISDIR(sb.st_mode) ||
301 (pwd->pw_uid && sb.st_uid == pwd->pw_uid &&
302 (sb.st_mode & S_IXUSR) == 0)) {
303 auth_setstate(as, (auth_getstate(as) & ~AUTH_ALLOW));
304 goto out;
305 }
306 }
307 if (approve)
308 auth_call(as, approve, strrchr(approve, '/') + 1, "--", name,
309 lc->lc_class, type, (char *)NULL);
310
311 out:
312 free(approve);
313 if (close_lc_on_exit)
314 login_close(lc);
315
316 if (close_on_exit)
317 return (auth_close(as));
318 return (auth_getstate(as) & AUTH_ALLOW);
319 }
320 DEF_WEAK(auth_approval);
321
322 auth_session_t *
auth_usercheck(char * name,char * style,char * type,char * password)323 auth_usercheck(char *name, char *style, char *type, char *password)
324 {
325 char namebuf[LOGIN_NAME_MAX + 1 + NAME_MAX + 1];
326 char pwbuf[_PW_BUF_LEN];
327 auth_session_t *as;
328 login_cap_t *lc;
329 struct passwd pwstore, *pwd = NULL;
330 char *slash;
331
332 if (!_auth_validuser(name))
333 return (NULL);
334 if (strlcpy(namebuf, name, sizeof(namebuf)) >= sizeof(namebuf))
335 return (NULL);
336 name = namebuf;
337
338 /*
339 * Split up user:style names if we were not given a style
340 */
341 if (style == NULL && (style = strchr(name, ':')) != NULL)
342 *style++ = '\0';
343
344 /*
345 * Cope with user/instance. We are only using this to get
346 * the class so it is okay if we strip a /root instance
347 * The actual login script will pay attention to the instance.
348 */
349 getpwnam_r(name, &pwstore, pwbuf, sizeof(pwbuf), &pwd);
350 if (pwd == NULL) {
351 if ((slash = strchr(name, '/')) != NULL) {
352 *slash = '\0';
353 getpwnam_r(name, &pwstore, pwbuf, sizeof(pwbuf), &pwd);
354 *slash = '/';
355 }
356 }
357 if ((lc = login_getclass(pwd ? pwd->pw_class : NULL)) == NULL)
358 return (NULL);
359
360 if ((style = login_getstyle(lc, style, type)) == NULL) {
361 login_close(lc);
362 return (NULL);
363 }
364
365 if (password) {
366 if ((as = auth_open()) == NULL) {
367 login_close(lc);
368 return (NULL);
369 }
370 auth_setitem(as, AUTHV_SERVICE, "response");
371 auth_setdata(as, "", 1);
372 auth_setdata(as, password, strlen(password) + 1);
373 explicit_bzero(password, strlen(password));
374 } else
375 as = NULL;
376 as = auth_verify(as, style, name, lc->lc_class, (char *)NULL);
377 login_close(lc);
378 return (as);
379 }
380 DEF_WEAK(auth_usercheck);
381
382 int
auth_userokay(char * name,char * style,char * type,char * password)383 auth_userokay(char *name, char *style, char *type, char *password)
384 {
385 auth_session_t *as;
386
387 as = auth_usercheck(name, style, type, password);
388
389 return (as != NULL ? auth_close(as) : 0);
390 }
391 DEF_WEAK(auth_userokay);
392
393 auth_session_t *
auth_userchallenge(char * name,char * style,char * type,char ** challengep)394 auth_userchallenge(char *name, char *style, char *type, char **challengep)
395 {
396 char namebuf[LOGIN_NAME_MAX + 1 + NAME_MAX + 1];
397 auth_session_t *as;
398 login_cap_t *lc;
399 struct passwd pwstore, *pwd = NULL;
400 char *slash, pwbuf[_PW_BUF_LEN];
401
402 if (!_auth_validuser(name))
403 return (NULL);
404 if (strlen(name) >= sizeof(namebuf))
405 return (NULL);
406 strlcpy(namebuf, name, sizeof namebuf);
407 name = namebuf;
408
409 /*
410 * Split up user:style names if we were not given a style
411 */
412 if (style == NULL && (style = strchr(name, ':')) != NULL)
413 *style++ = '\0';
414
415 /*
416 * Cope with user/instance. We are only using this to get
417 * the class so it is okay if we strip a /root instance
418 * The actual login script will pay attention to the instance.
419 */
420 getpwnam_r(name, &pwstore, pwbuf, sizeof(pwbuf), &pwd);
421 if (pwd == NULL) {
422 if ((slash = strchr(name, '/')) != NULL) {
423 *slash = '\0';
424 getpwnam_r(name, &pwstore, pwbuf, sizeof(pwbuf), &pwd);
425 *slash = '/';
426 }
427 }
428 if ((lc = login_getclass(pwd ? pwd->pw_class : NULL)) == NULL)
429 return (NULL);
430
431 if ((style = login_getstyle(lc, style, type)) == NULL ||
432 (as = auth_open()) == NULL) {
433 login_close(lc);
434 return (NULL);
435 }
436 if (auth_setitem(as, AUTHV_STYLE, style) < 0 ||
437 auth_setitem(as, AUTHV_NAME, name) < 0 ||
438 auth_setitem(as, AUTHV_CLASS, lc->lc_class) < 0) {
439 auth_close(as);
440 login_close(lc);
441 return (NULL);
442 }
443 login_close(lc);
444 *challengep = auth_challenge(as);
445 return (as);
446 }
447 DEF_WEAK(auth_userchallenge);
448
449 int
auth_userresponse(auth_session_t * as,char * response,int more)450 auth_userresponse(auth_session_t *as, char *response, int more)
451 {
452 char path[PATH_MAX];
453 char *style, *name, *challenge, *class;
454 int len;
455
456 if (as == NULL)
457 return (0);
458
459 auth_setstate(as, 0);
460
461 if ((style = auth_getitem(as, AUTHV_STYLE)) == NULL ||
462 (name = auth_getitem(as, AUTHV_NAME)) == NULL ||
463 !_auth_validuser(name)) {
464 if (more == 0)
465 return (auth_close(as));
466 return(0);
467 }
468
469 len = snprintf(path, sizeof(path), _PATH_AUTHPROG "%s", style);
470 if (len < 0 || len >= sizeof(path)) {
471 if (more == 0)
472 return (auth_close(as));
473 return (0);
474 }
475
476 challenge = auth_getitem(as, AUTHV_CHALLENGE);
477 class = auth_getitem(as, AUTHV_CLASS);
478
479 if (challenge)
480 auth_setdata(as, challenge, strlen(challenge) + 1);
481 else
482 auth_setdata(as, "", 1);
483 if (response) {
484 auth_setdata(as, response, strlen(response) + 1);
485 explicit_bzero(response, strlen(response));
486 } else
487 auth_setdata(as, "", 1);
488
489 auth_call(as, path, style, "-s", "response", "--", name,
490 class, (char *)NULL);
491
492 /*
493 * If they authenticated then make sure they did not expire
494 */
495 if (auth_getstate(as) & AUTH_ALLOW)
496 auth_check_expire(as);
497 if (more == 0)
498 return (auth_close(as));
499 return (auth_getstate(as) & AUTH_ALLOW);
500 }
501 DEF_WEAK(auth_userresponse);
502
503 /*
504 * Authenticate name with the specified style.
505 * If ``as'' is NULL a new session is formed with the default service.
506 * Returns NULL only if ``as'' is NULL and we were unable to allocate
507 * a new session.
508 *
509 * Use auth_close() or auth_getstate() to determine if the authentication
510 * worked.
511 */
512 auth_session_t *
auth_verify(auth_session_t * as,char * style,char * name,...)513 auth_verify(auth_session_t *as, char *style, char *name, ...)
514 {
515 va_list ap;
516 char path[PATH_MAX];
517
518 if ((name == NULL || style == NULL) && as == NULL)
519 return (NULL);
520
521 if (as == NULL && (as = auth_open()) == NULL)
522 return (NULL);
523 auth_setstate(as, 0);
524
525 if (style != NULL && auth_setitem(as, AUTHV_STYLE, style) < 0)
526 return (as);
527
528 if (name != NULL && auth_setitem(as, AUTHV_NAME, name) < 0)
529 return (as);
530
531 style = auth_getitem(as, AUTHV_STYLE);
532 name = auth_getitem(as, AUTHV_NAME);
533 if (!_auth_validuser(name))
534 return (as);
535
536 snprintf(path, sizeof(path), _PATH_AUTHPROG "%s", style);
537 va_start(ap, name);
538 auth_set_va_list(as, ap);
539 auth_call(as, path, auth_getitem(as, AUTHV_STYLE), "-s",
540 auth_getitem(as, AUTHV_SERVICE), "--", name, (char *)NULL);
541 va_end(ap);
542 return (as);
543 }
544 DEF_WEAK(auth_verify);
545