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