1 /*--
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993, 1994
5 * The Regents of the University of California. All rights reserved.
6 * Copyright (c) 2002 Networks Associates Technology, Inc.
7 * All rights reserved.
8 *
9 * Portions of this software were developed for the FreeBSD Project by
10 * ThinkSec AS and NAI Labs, the Security Research Division of Network
11 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
12 * ("CBOSS"), as part of the DARPA CHATS research program.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 * notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 * notice, this list of conditions and the following disclaimer in the
21 * documentation and/or other materials provided with the distribution.
22 * 3. Neither the name of the University nor the names of its contributors
23 * may be used to endorse or promote products derived from this software
24 * without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
38
39 #include <sys/cdefs.h>
40 __SCCSID("@(#)pw_util.c 8.3 (Berkeley) 4/2/94");
41
42 /*
43 * This file is used by all the "password" programs; vipw(8), chpass(1),
44 * and passwd(1).
45 */
46
47 #include <sys/param.h>
48 #include <sys/errno.h>
49 #include <sys/time.h>
50 #include <sys/resource.h>
51 #include <sys/stat.h>
52 #include <sys/wait.h>
53
54 #include <ctype.h>
55 #include <err.h>
56 #include <fcntl.h>
57 #include <inttypes.h>
58 #include <paths.h>
59 #include <pwd.h>
60 #include <signal.h>
61 #include <stdio.h>
62 #include <stdlib.h>
63 #include <string.h>
64 #include <unistd.h>
65
66 #include "libutil.h"
67
68 static pid_t editpid = -1;
69 static int lockfd = -1;
70 static char masterpasswd[PATH_MAX];
71 static char passwd_dir[PATH_MAX];
72 static char tempname[PATH_MAX];
73 static int initialized;
74
75 #if 0
76 void
77 pw_cont(int sig)
78 {
79
80 if (editpid != -1)
81 kill(editpid, sig);
82 }
83 #endif
84
85 /*
86 * Initialize statics and set limits, signals & umask to try to avoid
87 * interruptions, crashes etc. that might expose passord data.
88 */
89 int
pw_init(const char * dir,const char * master)90 pw_init(const char *dir, const char *master)
91 {
92 #if 0
93 struct rlimit rlim;
94 #endif
95
96 if (dir == NULL) {
97 strcpy(passwd_dir, _PATH_ETC);
98 } else {
99 if (strlen(dir) >= sizeof(passwd_dir)) {
100 errno = ENAMETOOLONG;
101 return (-1);
102 }
103 strcpy(passwd_dir, dir);
104 }
105
106 if (master == NULL) {
107 if (dir == NULL) {
108 strcpy(masterpasswd, _PATH_MASTERPASSWD);
109 } else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
110 passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
111 errno = ENAMETOOLONG;
112 return (-1);
113 }
114 } else {
115 if (strlen(master) >= sizeof(masterpasswd)) {
116 errno = ENAMETOOLONG;
117 return (-1);
118 }
119 strcpy(masterpasswd, master);
120 }
121
122 /*
123 * The code that follows is extremely disruptive to the calling
124 * process, and is therefore disabled until someone can conceive
125 * of a realistic scenario where it would fend off a compromise.
126 * Race conditions concerning the temporary files can be guarded
127 * against in other ways than masking signals (by checking stat(2)
128 * results after creation).
129 */
130 #if 0
131 /* Unlimited resource limits. */
132 rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
133 (void)setrlimit(RLIMIT_CPU, &rlim);
134 (void)setrlimit(RLIMIT_FSIZE, &rlim);
135 (void)setrlimit(RLIMIT_STACK, &rlim);
136 (void)setrlimit(RLIMIT_DATA, &rlim);
137 (void)setrlimit(RLIMIT_RSS, &rlim);
138
139 /* Don't drop core (not really necessary, but GP's). */
140 rlim.rlim_cur = rlim.rlim_max = 0;
141 (void)setrlimit(RLIMIT_CORE, &rlim);
142
143 /* Turn off signals. */
144 (void)signal(SIGALRM, SIG_IGN);
145 (void)signal(SIGHUP, SIG_IGN);
146 (void)signal(SIGINT, SIG_IGN);
147 (void)signal(SIGPIPE, SIG_IGN);
148 (void)signal(SIGQUIT, SIG_IGN);
149 (void)signal(SIGTERM, SIG_IGN);
150 (void)signal(SIGCONT, pw_cont);
151
152 /* Create with exact permissions. */
153 (void)umask(0);
154 #endif
155 initialized = 1;
156 return (0);
157 }
158
159 /*
160 * Lock the master password file.
161 */
162 int
pw_lock(void)163 pw_lock(void)
164 {
165
166 if (*masterpasswd == '\0')
167 return (-1);
168
169 /*
170 * If the master password file doesn't exist, the system is hosed.
171 * Might as well try to build one. Set the close-on-exec bit so
172 * that users can't get at the encrypted passwords while editing.
173 * Open should allow flock'ing the file; see 4.4BSD. XXX
174 */
175 for (;;) {
176 struct stat st;
177
178 lockfd = flopen(masterpasswd, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
179 if (lockfd == -1) {
180 if (errno == EWOULDBLOCK) {
181 errx(1, "the password db file is busy");
182 } else {
183 err(1, "could not lock the passwd file");
184 }
185 }
186
187 /*
188 * If the password file was replaced while we were trying to
189 * get the lock, our hardlink count will be 0 and we have to
190 * close and retry.
191 */
192 if (fstat(lockfd, &st) == -1)
193 err(1, "fstat() failed");
194 if (st.st_nlink != 0)
195 break;
196 close(lockfd);
197 lockfd = -1;
198 }
199 return (lockfd);
200 }
201
202 /*
203 * Create and open a presumably safe temp file for editing the password
204 * data, and copy the master password file into it.
205 */
206 int
pw_tmp(int mfd)207 pw_tmp(int mfd)
208 {
209 char buf[8192];
210 ssize_t nr;
211 const char *p;
212 int tfd;
213
214 if (*masterpasswd == '\0')
215 return (-1);
216 if ((p = strrchr(masterpasswd, '/')))
217 ++p;
218 else
219 p = masterpasswd;
220 if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
221 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
222 errno = ENAMETOOLONG;
223 return (-1);
224 }
225 if ((tfd = mkostemp(tempname, 0)) == -1)
226 return (-1);
227 if (mfd != -1) {
228 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
229 if (write(tfd, buf, (size_t)nr) != nr)
230 break;
231 if (nr != 0) {
232 unlink(tempname);
233 *tempname = '\0';
234 close(tfd);
235 return (-1);
236 }
237 }
238 return (tfd);
239 }
240
241 /*
242 * Regenerate the password database.
243 */
244 int
pw_mkdb(const char * user)245 pw_mkdb(const char *user)
246 {
247 int pstat;
248 pid_t pid;
249
250 (void)fflush(stderr);
251 switch ((pid = fork())) {
252 case -1:
253 return (-1);
254 case 0:
255 /* child */
256 if (user == NULL)
257 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
258 "-d", passwd_dir, tempname, (char *)NULL);
259 else
260 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
261 "-d", passwd_dir, "-u", user, tempname,
262 (char *)NULL);
263 _exit(1);
264 /* NOTREACHED */
265 default:
266 /* parent */
267 break;
268 }
269 if (waitpid(pid, &pstat, 0) == -1)
270 return (-1);
271 if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
272 return (0);
273 errno = 0;
274 return (-1);
275 }
276
277 /*
278 * Edit the temp file. Return -1 on error, >0 if the file was modified, 0
279 * if it was not.
280 */
281 int
pw_edit(int notsetuid)282 pw_edit(int notsetuid)
283 {
284 struct sigaction sa, sa_int, sa_quit;
285 sigset_t oldsigset, nsigset;
286 struct stat st1, st2;
287 const char *editor;
288 int pstat;
289
290 if ((editor = getenv("EDITOR")) == NULL)
291 editor = _PATH_VI;
292 if (stat(tempname, &st1) == -1)
293 return (-1);
294 sa.sa_handler = SIG_IGN;
295 sigemptyset(&sa.sa_mask);
296 sa.sa_flags = 0;
297 sigaction(SIGINT, &sa, &sa_int);
298 sigaction(SIGQUIT, &sa, &sa_quit);
299 sigemptyset(&nsigset);
300 sigaddset(&nsigset, SIGCHLD);
301 sigprocmask(SIG_BLOCK, &nsigset, &oldsigset);
302 switch ((editpid = fork())) {
303 case -1:
304 return (-1);
305 case 0:
306 sigaction(SIGINT, &sa_int, NULL);
307 sigaction(SIGQUIT, &sa_quit, NULL);
308 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
309 if (notsetuid) {
310 if (setgid(getgid()) == -1)
311 err(1, "setgid");
312 if (setuid(getuid()) == -1)
313 err(1, "setuid");
314 }
315 execlp(editor, editor, tempname, (char *)NULL);
316 err(1, "%s", editor);
317 default:
318 /* parent */
319 break;
320 }
321 for (;;) {
322 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
323 if (errno == EINTR)
324 continue;
325 unlink(tempname);
326 editpid = -1;
327 break;
328 } else if (WIFSTOPPED(pstat)) {
329 raise(WSTOPSIG(pstat));
330 } else if (WIFEXITED(pstat)) {
331 if (WEXITSTATUS(pstat) != 0)
332 errx(1, "\"%s\" exited with status %d", editor, WEXITSTATUS(pstat));
333 editpid = -1;
334 break;
335 } else {
336 unlink(tempname);
337 editpid = -1;
338 break;
339 }
340 }
341 sigaction(SIGINT, &sa_int, NULL);
342 sigaction(SIGQUIT, &sa_quit, NULL);
343 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
344 if (stat(tempname, &st2) == -1)
345 return (-1);
346 return (st1.st_mtim.tv_sec != st2.st_mtim.tv_sec ||
347 st1.st_mtim.tv_nsec != st2.st_mtim.tv_nsec);
348 }
349
350 /*
351 * Clean up. Preserve errno for the caller's convenience.
352 */
353 void
pw_fini(void)354 pw_fini(void)
355 {
356 int serrno, status;
357
358 if (!initialized)
359 return;
360 initialized = 0;
361 serrno = errno;
362 if (editpid != -1) {
363 kill(editpid, SIGTERM);
364 kill(editpid, SIGCONT);
365 waitpid(editpid, &status, 0);
366 editpid = -1;
367 }
368 if (*tempname != '\0') {
369 unlink(tempname);
370 *tempname = '\0';
371 }
372 if (lockfd != -1)
373 close(lockfd);
374 errno = serrno;
375 }
376
377 /*
378 * Compares two struct pwds.
379 */
380 int
pw_equal(const struct passwd * pw1,const struct passwd * pw2)381 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
382 {
383 return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
384 pw1->pw_uid == pw2->pw_uid &&
385 pw1->pw_gid == pw2->pw_gid &&
386 strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
387 pw1->pw_change == pw2->pw_change &&
388 pw1->pw_expire == pw2->pw_expire &&
389 strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
390 strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
391 strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
392 }
393
394 /*
395 * Make a passwd line out of a struct passwd.
396 */
397 char *
pw_make(const struct passwd * pw)398 pw_make(const struct passwd *pw)
399 {
400 char *line;
401
402 asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
403 pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
404 pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
405 pw->pw_gecos, pw->pw_dir, pw->pw_shell);
406 return (line);
407 }
408
409 /*
410 * Make a passwd line (in v7 format) out of a struct passwd
411 */
412 char *
pw_make_v7(const struct passwd * pw)413 pw_make_v7(const struct passwd *pw)
414 {
415 char *line;
416
417 asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
418 (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
419 pw->pw_gecos, pw->pw_dir, pw->pw_shell);
420 return (line);
421 }
422
423 /*
424 * Copy password file from one descriptor to another, replacing, deleting
425 * or adding a single record on the way.
426 */
427 int
pw_copy(int ffd,int tfd,const struct passwd * pw,struct passwd * old_pw)428 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
429 {
430 char *buf, *end, *line, *p, *q, *r, *tmp;
431 struct passwd *fpw;
432 const struct passwd *spw;
433 size_t len, size;
434 int eof, readlen;
435 char t;
436
437 if (old_pw == NULL && pw == NULL)
438 return (-1);
439
440 spw = old_pw;
441 /* deleting a user */
442 if (pw == NULL) {
443 line = NULL;
444 } else {
445 if ((line = pw_make(pw)) == NULL)
446 return (-1);
447 }
448
449 /* adding a user */
450 if (spw == NULL)
451 spw = pw;
452
453 /* initialize the buffer */
454 if ((buf = malloc(size = 1024)) == NULL)
455 goto err;
456
457 eof = 0;
458 len = 0;
459 p = q = end = buf;
460 for (;;) {
461 /* find the end of the current line */
462 for (p = q; q < end && *q != '\0'; ++q)
463 if (*q == '\n')
464 break;
465
466 /* if we don't have a complete line, fill up the buffer */
467 if (q >= end) {
468 if (eof)
469 break;
470 while ((size_t)(q - p) >= size) {
471 if ((tmp = reallocarray(buf, 2, size)) == NULL) {
472 warnx("passwd line too long");
473 goto err;
474 }
475 p = tmp + (p - buf);
476 q = tmp + (q - buf);
477 end = tmp + (end - buf);
478 buf = tmp;
479 size = size * 2;
480 }
481 if (p < end) {
482 q = memmove(buf, p, end - p);
483 end -= p - buf;
484 } else {
485 p = q = end = buf;
486 }
487 readlen = read(ffd, end, size - (end - buf));
488 if (readlen == -1)
489 goto err;
490 else
491 len = (size_t)readlen;
492 if (len == 0 && p == buf)
493 break;
494 end += len;
495 len = end - buf;
496 if (len < size) {
497 eof = 1;
498 if (len > 0 && buf[len - 1] != '\n')
499 ++len, *end++ = '\n';
500 }
501 continue;
502 }
503
504 /* is it a blank line or a comment? */
505 for (r = p; r < q && isspace(*r); ++r)
506 /* nothing */ ;
507 if (r == q || *r == '#') {
508 /* yep */
509 if (write(tfd, p, q - p + 1) != q - p + 1)
510 goto err;
511 ++q;
512 continue;
513 }
514
515 /* is it the one we're looking for? */
516
517 t = *q;
518 *q = '\0';
519
520 fpw = pw_scan(r, PWSCAN_MASTER);
521
522 /*
523 * fpw is either the struct passwd for the current line,
524 * or NULL if the line is malformed.
525 */
526
527 *q = t;
528 if (fpw == NULL || strcmp(fpw->pw_name, spw->pw_name) != 0) {
529 /* nope */
530 if (fpw != NULL)
531 free(fpw);
532 if (write(tfd, p, q - p + 1) != q - p + 1)
533 goto err;
534 ++q;
535 continue;
536 }
537 if (old_pw && !pw_equal(fpw, old_pw)) {
538 warnx("entry inconsistent");
539 free(fpw);
540 errno = EINVAL; /* hack */
541 goto err;
542 }
543 free(fpw);
544
545 /* it is, replace or remove it */
546 if (line != NULL) {
547 len = strlen(line);
548 if (write(tfd, line, len) != (int)len)
549 goto err;
550 } else {
551 /* when removed, avoid the \n */
552 q++;
553 }
554 /* we're done, just copy the rest over */
555 for (;;) {
556 if (write(tfd, q, end - q) != end - q)
557 goto err;
558 q = buf;
559 readlen = read(ffd, buf, size);
560 if (readlen == 0)
561 break;
562 else
563 len = (size_t)readlen;
564 if (readlen == -1)
565 goto err;
566 end = buf + len;
567 }
568 goto done;
569 }
570
571 /* if we got here, we didn't find the old entry */
572 if (line == NULL) {
573 errno = ENOENT;
574 goto err;
575 }
576 len = strlen(line);
577 if ((size_t)write(tfd, line, len) != len ||
578 write(tfd, "\n", 1) != 1)
579 goto err;
580 done:
581 free(line);
582 free(buf);
583 return (0);
584 err:
585 free(line);
586 free(buf);
587 return (-1);
588 }
589
590 /*
591 * Return the current value of tempname.
592 */
593 const char *
pw_tempname(void)594 pw_tempname(void)
595 {
596
597 return (tempname);
598 }
599
600 /*
601 * Duplicate a struct passwd.
602 */
603 struct passwd *
pw_dup(const struct passwd * pw)604 pw_dup(const struct passwd *pw)
605 {
606 char *dst;
607 struct passwd *npw;
608 ssize_t len;
609
610 len = sizeof(*npw);
611 if (pw->pw_name != NULL)
612 len += strlen(pw->pw_name) + 1;
613 if (pw->pw_passwd != NULL)
614 len += strlen(pw->pw_passwd) + 1;
615 if (pw->pw_class != NULL)
616 len += strlen(pw->pw_class) + 1;
617 if (pw->pw_gecos != NULL)
618 len += strlen(pw->pw_gecos) + 1;
619 if (pw->pw_dir != NULL)
620 len += strlen(pw->pw_dir) + 1;
621 if (pw->pw_shell != NULL)
622 len += strlen(pw->pw_shell) + 1;
623 if ((npw = malloc((size_t)len)) == NULL)
624 return (NULL);
625 memcpy(npw, pw, sizeof(*npw));
626 dst = (char *)npw + sizeof(*npw);
627 if (pw->pw_name != NULL) {
628 npw->pw_name = dst;
629 dst = stpcpy(npw->pw_name, pw->pw_name) + 1;
630 }
631 if (pw->pw_passwd != NULL) {
632 npw->pw_passwd = dst;
633 dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1;
634 }
635 if (pw->pw_class != NULL) {
636 npw->pw_class = dst;
637 dst = stpcpy(npw->pw_class, pw->pw_class) + 1;
638 }
639 if (pw->pw_gecos != NULL) {
640 npw->pw_gecos = dst;
641 dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1;
642 }
643 if (pw->pw_dir != NULL) {
644 npw->pw_dir = dst;
645 dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1;
646 }
647 if (pw->pw_shell != NULL) {
648 npw->pw_shell = dst;
649 dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1;
650 }
651 return (npw);
652 }
653
654 #include "pw_scan.h"
655
656 /*
657 * Wrapper around some internal libc functions.
658 */
659
660 void
pw_initpwd(struct passwd * pw)661 pw_initpwd(struct passwd *pw)
662 {
663
664 __pw_initpwd(pw);
665 }
666
667 struct passwd *
pw_scan(const char * line,int flags)668 pw_scan(const char *line, int flags)
669 {
670 struct passwd pw, *ret;
671 char *bp;
672
673 if ((bp = strdup(line)) == NULL)
674 return (NULL);
675 __pw_initpwd(&pw);
676 if (!__pw_scan(bp, &pw, flags)) {
677 free(bp);
678 return (NULL);
679 }
680 ret = pw_dup(&pw);
681 free(bp);
682 return (ret);
683 }
684