Do not dereference a null pointer for a malformed line in master.passwd.
[dragonfly.git] / lib / libutil / pw_util.c
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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.
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20 * 4. 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 *
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36 * @(#)pw_util.c 8.3 (Berkeley) 4/2/94
37 * $FreeBSD: src/lib/libutil/pw_util.c,v 1.38 2007/01/09 01:02:05 imp Exp $
faedbd2a 38 * $DragonFly: src/lib/libutil/pw_util.c,v 1.2 2007/12/30 13:44:33 matthias Exp $
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39 */
40
41/*
42 * This file is used by all the "password" programs; vipw(8), chpass(1),
43 * and passwd(1).
44 */
45
46#include <sys/param.h>
47#include <sys/errno.h>
48#include <sys/time.h>
49#include <sys/resource.h>
50#include <sys/stat.h>
51#include <sys/wait.h>
52
53#include <ctype.h>
54#include <err.h>
55#include <fcntl.h>
56#include <inttypes.h>
57#include <libgen.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
68static pid_t editpid = -1;
69static int lockfd = -1;
70static char masterpasswd[PATH_MAX];
71static char passwd_dir[PATH_MAX];
72static char tempname[PATH_MAX];
73static int initialized;
74
75#if 0
76void
77pw_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 */
89int
90pw_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 */
162int
163pw_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 = open(masterpasswd, O_RDONLY, 0);
179 if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
180 err(1, "%s", masterpasswd);
181 /* XXX vulnerable to race conditions */
182 if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
183 if (errno == EWOULDBLOCK) {
184 errx(1, "the password db file is busy");
185 } else {
186 err(1, "could not lock the passwd file: ");
187 }
188 }
189
190 /*
191 * If the password file was replaced while we were trying to
192 * get the lock, our hardlink count will be 0 and we have to
193 * close and retry.
194 */
195 if (fstat(lockfd, &st) == -1)
196 err(1, "fstat() failed: ");
197 if (st.st_nlink != 0)
198 break;
199 close(lockfd);
200 lockfd = -1;
201 }
202 return (lockfd);
203}
204
205/*
206 * Create and open a presumably safe temp file for editing the password
207 * data, and copy the master password file into it.
208 */
209int
210pw_tmp(int mfd)
211{
212 char buf[8192];
213 ssize_t nr;
214 const char *p;
215 int tfd;
216
217 if (*masterpasswd == '\0')
218 return (-1);
219 if ((p = strrchr(masterpasswd, '/')))
220 ++p;
221 else
222 p = masterpasswd;
223 if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
224 (int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
225 errno = ENAMETOOLONG;
226 return (-1);
227 }
228 if ((tfd = mkstemp(tempname)) == -1)
229 return (-1);
230 if (mfd != -1) {
231 while ((nr = read(mfd, buf, sizeof(buf))) > 0)
232 if (write(tfd, buf, (size_t)nr) != nr)
233 break;
234 if (nr != 0) {
235 unlink(tempname);
236 *tempname = '\0';
237 close(tfd);
238 return (-1);
239 }
240 }
241 return (tfd);
242}
243
244/*
245 * Regenerate the password database.
246 */
247int
248pw_mkdb(const char *user)
249{
250 int pstat;
251 pid_t pid;
252
253 (void)fflush(stderr);
254 switch ((pid = fork())) {
255 case -1:
256 return (-1);
257 case 0:
258 /* child */
259 if (user == NULL)
260 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
261 "-d", passwd_dir, tempname, (char *)NULL);
262 else
263 execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
264 "-d", passwd_dir, "-u", user, tempname,
265 (char *)NULL);
266 _exit(1);
267 /* NOTREACHED */
268 default:
269 /* parent */
270 break;
271 }
272 if (waitpid(pid, &pstat, 0) == -1)
273 return (-1);
274 if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
275 return (0);
276 errno = 0;
277 return (-1);
278}
279
280/*
281 * Edit the temp file. Return -1 on error, >0 if the file was modified, 0
282 * if it was not.
283 */
284int
285pw_edit(int notsetuid)
286{
287 struct sigaction sa, sa_int, sa_quit;
288 sigset_t oldsigset, sigset;
289 struct stat st1, st2;
290 const char *editor;
291 int pstat;
292
293 if ((editor = getenv("EDITOR")) == NULL)
294 editor = _PATH_VI;
295 if (stat(tempname, &st1) == -1)
296 return (-1);
297 sa.sa_handler = SIG_IGN;
298 sigemptyset(&sa.sa_mask);
299 sa.sa_flags = 0;
300 sigaction(SIGINT, &sa, &sa_int);
301 sigaction(SIGQUIT, &sa, &sa_quit);
302 sigemptyset(&sigset);
303 sigaddset(&sigset, SIGCHLD);
304 sigprocmask(SIG_BLOCK, &sigset, &oldsigset);
305 switch ((editpid = fork())) {
306 case -1:
307 return (-1);
308 case 0:
309 sigaction(SIGINT, &sa_int, NULL);
310 sigaction(SIGQUIT, &sa_quit, NULL);
311 sigprocmask(SIG_SETMASK, &oldsigset, NULL);
312 if (notsetuid) {
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313 setgid(getgid());
314 setuid(getuid());
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315 }
316 errno = 0;
317 execlp(editor, basename(editor), tempname, (char *)NULL);
318 _exit(errno);
319 default:
320 /* parent */
321 break;
322 }
323 for (;;) {
324 if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
325 if (errno == EINTR)
326 continue;
327 unlink(tempname);
328 editpid = -1;
329 break;
330 } else if (WIFSTOPPED(pstat)) {
331 raise(WSTOPSIG(pstat));
332 } else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
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_mtime != st2.st_mtime);
347}
348
349/*
350 * Clean up. Preserve errno for the caller's convenience.
351 */
352void
353pw_fini(void)
354{
355 int serrno, status;
356
357 if (!initialized)
358 return;
359 initialized = 0;
360 serrno = errno;
361 if (editpid != -1) {
362 kill(editpid, SIGTERM);
363 kill(editpid, SIGCONT);
364 waitpid(editpid, &status, 0);
365 editpid = -1;
366 }
367 if (*tempname != '\0') {
368 unlink(tempname);
369 *tempname = '\0';
370 }
371 if (lockfd != -1)
372 close(lockfd);
373 errno = serrno;
374}
375
376/*
377 * Compares two struct pwds.
378 */
379int
380pw_equal(const struct passwd *pw1, const struct passwd *pw2)
381{
382 return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
383 pw1->pw_uid == pw2->pw_uid &&
384 pw1->pw_gid == pw2->pw_gid &&
385 strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
386 pw1->pw_change == pw2->pw_change &&
387 pw1->pw_expire == pw2->pw_expire &&
388 strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
389 strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
390 strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
391}
392
393/*
394 * Make a passwd line out of a struct passwd.
395 */
396char *
397pw_make(const struct passwd *pw)
398{
399 char *line;
400
401 asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
402 pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
403 pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
404 pw->pw_gecos, pw->pw_dir, pw->pw_shell);
405 return line;
406}
407
408/*
409 * Copy password file from one descriptor to another, replacing or adding
410 * a single record on the way.
411 */
412int
413pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
414{
415 char buf[8192], *end, *line, *p, *q, *r, t;
416 struct passwd *fpw;
417 size_t len;
418 int eof, readlen;
419
420 if ((line = pw_make(pw)) == NULL)
421 return (-1);
422
423 eof = 0;
424 len = 0;
425 p = q = end = buf;
426 for (;;) {
427 /* find the end of the current line */
428 for (p = q; q < end && *q != '\0'; ++q)
429 if (*q == '\n')
430 break;
431
432 /* if we don't have a complete line, fill up the buffer */
433 if (q >= end) {
434 if (eof)
435 break;
436 if ((size_t)(q - p) >= sizeof(buf)) {
437 warnx("passwd line too long");
438 errno = EINVAL; /* hack */
439 goto err;
440 }
441 if (p < end) {
442 q = memmove(buf, p, end - p);
443 end -= p - buf;
444 } else {
445 p = q = end = buf;
446 }
447 readlen = read(ffd, end, sizeof(buf) - (end - buf));
448 if (readlen == -1)
449 goto err;
450 else
451 len = (size_t)readlen;
452 if (len == 0 && p == buf)
453 break;
454 end += len;
455 len = end - buf;
456 if (len < (ssize_t)sizeof(buf)) {
457 eof = 1;
458 if (len > 0 && buf[len - 1] != '\n')
459 ++len, *end++ = '\n';
460 }
461 continue;
462 }
463
464 /* is it a blank line or a comment? */
465 for (r = p; r < q && isspace(*r); ++r)
466 /* nothing */ ;
467 if (r == q || *r == '#') {
468 /* yep */
469 if (write(tfd, p, q - p + 1) != q - p + 1)
470 goto err;
471 ++q;
472 continue;
473 }
474
475 /* is it the one we're looking for? */
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477 t = *q;
478 *q = '\0';
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479
480 fpw = pw_scan(r, PWSCAN_MASTER);
481
482 /*
483 * fpw is either the struct passwd for the current line,
484 * or NULL if the line is malformed.
485 */
486
ee8287f8 487 *q = t;
feed9a49 488 if (fpw == NULL || strcmp(fpw->pw_name, pw->pw_name) != 0) {
ee8287f8 489 /* nope */
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490 if (fpw != NULL)
491 free(fpw);
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492 if (write(tfd, p, q - p + 1) != q - p + 1)
493 goto err;
494 ++q;
495 continue;
496 }
497 if (old_pw && !pw_equal(fpw, old_pw)) {
498 warnx("entry inconsistent");
499 free(fpw);
500 errno = EINVAL; /* hack */
501 goto err;
502 }
503 free(fpw);
504
505 /* it is, replace it */
506 len = strlen(line);
507 if (write(tfd, line, len) != (int)len)
508 goto err;
509
510 /* we're done, just copy the rest over */
511 for (;;) {
512 if (write(tfd, q, end - q) != end - q)
513 goto err;
514 q = buf;
515 readlen = read(ffd, buf, sizeof(buf));
516 if (readlen == 0)
517 break;
518 else
519 len = (size_t)readlen;
520 if (readlen == -1)
521 goto err;
522 end = buf + len;
523 }
524 goto done;
525 }
526
527 /* if we got here, we have a new entry */
528 len = strlen(line);
529 if ((size_t)write(tfd, line, len) != len ||
530 write(tfd, "\n", 1) != 1)
531 goto err;
532 done:
533 free(line);
534 return (0);
535 err:
536 free(line);
537 return (-1);
538}
539
540/*
541 * Return the current value of tempname.
542 */
543const char *
544pw_tempname(void)
545{
546
547 return (tempname);
548}
549
550/*
551 * Duplicate a struct passwd.
552 */
553struct passwd *
554pw_dup(const struct passwd *pw)
555{
556 struct passwd *npw;
557 ssize_t len;
558
559 len = sizeof(*npw) +
560 (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) +
561 (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) +
562 (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) +
563 (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) +
564 (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) +
565 (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0);
566 if ((npw = malloc((size_t)len)) == NULL)
567 return (NULL);
568 memcpy(npw, pw, sizeof(*npw));
569 len = sizeof(*npw);
570 if (pw->pw_name) {
571 npw->pw_name = ((char *)npw) + len;
572 len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1;
573 }
574 if (pw->pw_passwd) {
575 npw->pw_passwd = ((char *)npw) + len;
576 len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1;
577 }
578 if (pw->pw_class) {
579 npw->pw_class = ((char *)npw) + len;
580 len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1;
581 }
582 if (pw->pw_gecos) {
583 npw->pw_gecos = ((char *)npw) + len;
584 len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1;
585 }
586 if (pw->pw_dir) {
587 npw->pw_dir = ((char *)npw) + len;
588 len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1;
589 }
590 if (pw->pw_shell) {
591 npw->pw_shell = ((char *)npw) + len;
592 len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1;
593 }
594 return (npw);
595}
596
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597#include "pw_scan.h"
598
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599/*
600 * Wrapper around an internal libc function
601 */
602struct passwd *
603pw_scan(const char *line, int flags)
604{
605 struct passwd pw, *ret;
606 char *bp;
607
608 if ((bp = strdup(line)) == NULL)
609 return (NULL);
610 if (!__pw_scan(bp, &pw, flags)) {
611 free(bp);
612 return (NULL);
613 }
614 ret = pw_dup(&pw);
615 free(bp);
616 return (ret);
617}