1 /*-
2 * Copyright (c) 1990, 1993, 1994
3 * The Regents of the University of California. All rights reserved.
4 * Copyright (c) 2002 Networks Associates Technology, Inc.
5 * All rights reserved.
6 *
7 * Portions of this software were developed for the FreeBSD Project by
8 * ThinkSec AS and NAI Labs, the Security Research Division of Network
9 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035
10 * ("CBOSS"), as part of the DARPA CHATS research program.
11 *
12 * Redistribution and use in source and binary forms, with or without
13 * modification, are permitted provided that the following conditions
14 * are met:
15 * 1. Redistributions of source code must retain the above copyright
16 * notice, this list of conditions and the following disclaimer.
17 * 2. Redistributions in binary form must reproduce the above copyright
18 * notice, this list of conditions and the following disclaimer in the
19 * documentation and/or other materials provided with the distribution.
20 * 3. Neither the name of the University nor the names of its contributors
21 * may be used to endorse or promote products derived from this software
22 * without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 *
36 * @(#)pw_util.c 8.3 (Berkeley) 4/2/94
37 * $FreeBSD: head/lib/libutil/pw_util.c 244744 2012-12-27 20:24:44Z bapt $
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 <libgen.h>
57 #include <paths.h>
58 #include <pwd.h>
59 #include <signal.h>
60 #include <stdio.h>
61 #include <stdlib.h>
62 #include <string.h>
63 #include <unistd.h>
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 = mkstemp(tempname)) == -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, NULL);
257 else
258 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
259 "-d", passwd_dir, "-u", user, tempname,
260 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 (void)setgid(getgid());
309 (void)setuid(getuid());
310 }
311 errno = 0;
312 execlp(editor, basename(strdup(editor)), tempname, NULL);
313 _exit(errno);
314 default:
315 /* parent */
316 break;
317 }
318 for (;;) {
319 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
320 if (errno == EINTR)
321 continue;
322 unlink(tempname);
323 editpid = -1;
324 break;
325 } else if (WIFSTOPPED(pstat)) {
326 raise(WSTOPSIG(pstat));
327 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
328 editpid = -1;
329 break;
330 } else {
331 unlink(tempname);
332 editpid = -1;
333 break;
334 }
335 }
336 sigaction(SIGINT, &sa_int, NULL);
337 sigaction(SIGQUIT, &sa_quit, NULL);
338 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
339 if (stat(tempname, &st2) == -1)
340 return (-1);
341 return (st1.st_mtim.tv_sec != st2.st_mtim.tv_sec ||
342 st1.st_mtim.tv_nsec != st2.st_mtim.tv_nsec);
343 }
344
345 /*
346 * Clean up. Preserve errno for the caller's convenience.
347 */
348 void
pw_fini(void)349 pw_fini(void)
350 {
351 int serrno, status;
352
353 if (!initialized)
354 return;
355 initialized = 0;
356 serrno = errno;
357 if (editpid != -1) {
358 kill(editpid, SIGTERM);
359 kill(editpid, SIGCONT);
360 waitpid(editpid, &status, 0);
361 editpid = -1;
362 }
363 if (*tempname != '\0') {
364 unlink(tempname);
365 *tempname = '\0';
366 }
367 if (lockfd != -1)
368 close(lockfd);
369 errno = serrno;
370 }
371
372 /*
373 * Compares two struct pwds.
374 */
375 int
pw_equal(const struct passwd * pw1,const struct passwd * pw2)376 pw_equal(const struct passwd *pw1, const struct passwd *pw2)
377 {
378 return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
379 pw1->pw_uid == pw2->pw_uid &&
380 pw1->pw_gid == pw2->pw_gid &&
381 strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
382 pw1->pw_change == pw2->pw_change &&
383 pw1->pw_expire == pw2->pw_expire &&
384 strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
385 strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
386 strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
387 }
388
389 /*
390 * Make a passwd line out of a struct passwd.
391 */
392 char *
pw_make(const struct passwd * pw)393 pw_make(const struct passwd *pw)
394 {
395 char *line;
396
397 asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
398 pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
399 pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
400 pw->pw_gecos, pw->pw_dir, pw->pw_shell);
401 return (line);
402 }
403
404 /*
405 * Make a passwd line (in v7 format) out of a struct passwd
406 */
407 char *
pw_make_v7(const struct passwd * pw)408 pw_make_v7(const struct passwd *pw)
409 {
410 char *line;
411
412 asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
413 (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
414 pw->pw_gecos, pw->pw_dir, pw->pw_shell);
415 return (line);
416 }
417
418 /*
419 * Copy password file from one descriptor to another, replacing, deleting
420 * or adding a single record on the way.
421 */
422 int
pw_copy(int ffd,int tfd,const struct passwd * pw,struct passwd * old_pw)423 pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
424 {
425 char buf[8192], *end, *line, *p, *q, *r, t;
426 struct passwd *fpw;
427 const struct passwd *spw;
428 size_t len;
429 int eof, readlen;
430
431 if (old_pw == NULL && pw == NULL)
432 return (-1);
433
434 spw = old_pw;
435 /* deleting a user */
436 if (pw == NULL) {
437 line = NULL;
438 } else {
439 if ((line = pw_make(pw)) == NULL)
440 return (-1);
441 }
442
443 /* adding a user */
444 if (spw == NULL)
445 spw = pw;
446
447 eof = 0;
448 len = 0;
449 p = q = end = buf;
450 for (;;) {
451 /* find the end of the current line */
452 for (p = q; q < end && *q != '\0'; ++q)
453 if (*q == '\n')
454 break;
455
456 /* if we don't have a complete line, fill up the buffer */
457 if (q >= end) {
458 if (eof)
459 break;
460 if ((size_t)(q - p) >= sizeof(buf)) {
461 warnx("passwd line too long");
462 errno = EINVAL; /* hack */
463 goto err;
464 }
465 if (p < end) {
466 q = memmove(buf, p, end - p);
467 end -= p - buf;
468 } else {
469 p = q = end = buf;
470 }
471 readlen = read(ffd, end, sizeof(buf) - (end - buf));
472 if (readlen == -1)
473 goto err;
474 else
475 len = (size_t)readlen;
476 if (len == 0 && p == buf)
477 break;
478 end += len;
479 len = end - buf;
480 if (len < (ssize_t)sizeof(buf)) {
481 eof = 1;
482 if (len > 0 && buf[len - 1] != '\n')
483 ++len, *end++ = '\n';
484 }
485 continue;
486 }
487
488 /* is it a blank line or a comment? */
489 for (r = p; r < q && isspace(*r); ++r)
490 /* nothing */ ;
491 if (r == q || *r == '#') {
492 /* yep */
493 if (write(tfd, p, q - p + 1) != q - p + 1)
494 goto err;
495 ++q;
496 continue;
497 }
498
499 /* is it the one we're looking for? */
500
501 t = *q;
502 *q = '\0';
503
504 fpw = pw_scan(r, PWSCAN_MASTER);
505
506 /*
507 * fpw is either the struct passwd for the current line,
508 * or NULL if the line is malformed.
509 */
510
511 *q = t;
512 if (fpw == NULL || strcmp(fpw->pw_name, spw->pw_name) != 0) {
513 /* nope */
514 if (fpw != NULL)
515 free(fpw);
516 if (write(tfd, p, q - p + 1) != q - p + 1)
517 goto err;
518 ++q;
519 continue;
520 }
521 if (old_pw && !pw_equal(fpw, old_pw)) {
522 warnx("entry inconsistent");
523 free(fpw);
524 errno = EINVAL; /* hack */
525 goto err;
526 }
527 free(fpw);
528
529 /* it is, replace or remove it */
530 if (line != NULL) {
531 len = strlen(line);
532 if (write(tfd, line, len) != (int)len)
533 goto err;
534 } else {
535 /* when removed, avoid the \n */
536 q++;
537 }
538 /* we're done, just copy the rest over */
539 for (;;) {
540 if (write(tfd, q, end - q) != end - q)
541 goto err;
542 q = buf;
543 readlen = read(ffd, buf, sizeof(buf));
544 if (readlen == 0)
545 break;
546 else
547 len = (size_t)readlen;
548 if (readlen == -1)
549 goto err;
550 end = buf + len;
551 }
552 goto done;
553 }
554
555 /* if we got here, we didn't find the old entry */
556 if (line == NULL) {
557 errno = ENOENT;
558 goto err;
559 }
560 len = strlen(line);
561 if ((size_t)write(tfd, line, len) != len ||
562 write(tfd, "\n", 1) != 1)
563 goto err;
564 done:
565 if (line != NULL)
566 free(line);
567 return (0);
568 err:
569 if (line != NULL)
570 free(line);
571 return (-1);
572 }
573
574 /*
575 * Return the current value of tempname.
576 */
577 const char *
pw_tempname(void)578 pw_tempname(void)
579 {
580
581 return (tempname);
582 }
583
584 /*
585 * Duplicate a struct passwd.
586 */
587 struct passwd *
pw_dup(const struct passwd * pw)588 pw_dup(const struct passwd *pw)
589 {
590 char *dst;
591 struct passwd *npw;
592 ssize_t len;
593
594 len = sizeof(*npw);
595 if (pw->pw_name != NULL)
596 len += strlen(pw->pw_name) + 1;
597 if (pw->pw_passwd != NULL)
598 len += strlen(pw->pw_passwd) + 1;
599 if (pw->pw_class != NULL)
600 len += strlen(pw->pw_class) + 1;
601 if (pw->pw_gecos != NULL)
602 len += strlen(pw->pw_gecos) + 1;
603 if (pw->pw_dir != NULL)
604 len += strlen(pw->pw_dir) + 1;
605 if (pw->pw_shell != NULL)
606 len += strlen(pw->pw_shell) + 1;
607 if ((npw = malloc((size_t)len)) == NULL)
608 return (NULL);
609 memcpy(npw, pw, sizeof(*npw));
610 dst = (char *)npw + sizeof(*npw);
611 if (pw->pw_name != NULL) {
612 npw->pw_name = dst;
613 dst = stpcpy(npw->pw_name, pw->pw_name) + 1;
614 }
615 if (pw->pw_passwd != NULL) {
616 npw->pw_passwd = dst;
617 dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1;
618 }
619 if (pw->pw_class != NULL) {
620 npw->pw_class = dst;
621 dst = stpcpy(npw->pw_class, pw->pw_class) + 1;
622 }
623 if (pw->pw_gecos != NULL) {
624 npw->pw_gecos = dst;
625 dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1;
626 }
627 if (pw->pw_dir != NULL) {
628 npw->pw_dir = dst;
629 dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1;
630 }
631 if (pw->pw_shell != NULL) {
632 npw->pw_shell = dst;
633 dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1;
634 }
635 return (npw);
636 }
637
638 #include "pw_scan.h"
639
640 /*
641 * Wrapper around an internal libc function
642 */
643 struct passwd *
pw_scan(const char * line,int flags)644 pw_scan(const char *line, int flags)
645 {
646 struct passwd pw, *ret;
647 char *bp;
648
649 if ((bp = strdup(line)) == NULL)
650 return (NULL);
651 if (!__pw_scan(bp, &pw, flags)) {
652 free(bp);
653 return (NULL);
654 }
655 ret = pw_dup(&pw);
656 free(bp);
657 return (ret);
658 }
659