pw_util.c revision 96199 
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. All advertising materials mentioning features or use of this software
21 *    must display the following acknowledgement:
22 *	This product includes software developed by the University of
23 *	California, Berkeley and its contributors.
24 * 4. Neither the name of the University nor the names of its contributors
25 *    may be used to endorse or promote products derived from this software
26 *    without specific prior written permission.
27 *
28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
31 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
38 * SUCH DAMAGE.
39 */
40
41#ifndef lint
42#if 0
43static const char sccsid[] = "@(#)pw_util.c	8.3 (Berkeley) 4/2/94";
44#endif
45static const char rcsid[] =
46  "$FreeBSD: head/lib/libutil/pw_util.c 96199 2002-05-08 00:50:07Z des $";
47#endif /* not lint */
48
49/*
50 * This file is used by all the "password" programs; vipw(8), chpass(1),
51 * and passwd(1).
52 */
53
54#include <sys/param.h>
55#include <sys/errno.h>
56#include <sys/time.h>
57#include <sys/resource.h>
58#include <sys/stat.h>
59#include <sys/wait.h>
60
61#include <err.h>
62#include <ctype.h>
63#include <fcntl.h>
64#include <inttypes.h>
65#include <libgen.h>
66#include <paths.h>
67#include <pwd.h>
68#include <signal.h>
69#include <stdio.h>
70#include <stdlib.h>
71#include <string.h>
72#include <unistd.h>
73
74#include <libutil.h>
75
76static pid_t editpid = -1;
77static int lockfd = -1;
78static char masterpasswd[PATH_MAX];
79static char passwd_dir[PATH_MAX];
80static char tempname[PATH_MAX];
81static int initialized;
82
83void
84pw_cont(int sig)
85{
86
87	if (editpid != -1)
88		kill(editpid, sig);
89}
90
91/*
92 * Initialize statics and set limits, signals & umask to try to avoid
93 * interruptions, crashes etc. that might expose passord data.
94 */
95int
96pw_init(const char *dir, const char *master)
97{
98#if 0
99	struct rlimit rlim;
100#endif
101
102	if (dir == NULL) {
103		strcpy(passwd_dir, _PATH_ETC);
104	} else {
105		if (strlen(dir) >= sizeof passwd_dir) {
106			errno = ENAMETOOLONG;
107			return (-1);
108		}
109		strcpy(passwd_dir, dir);
110	}
111
112	if (master == NULL) {
113		if (dir == NULL) {
114			strcpy(masterpasswd, _PATH_MASTERPASSWD);
115		} else if (snprintf(masterpasswd, sizeof masterpasswd, "%s/%s",
116		    passwd_dir, _MASTERPASSWD) > sizeof masterpasswd) {
117			errno = ENAMETOOLONG;
118			return (-1);
119		}
120	} else {
121		if (strlen(master) >= sizeof masterpasswd) {
122			errno = ENAMETOOLONG;
123			return (-1);
124		}
125		strcpy(masterpasswd, master);
126	}
127
128	/*
129	 * The code that follows is extremely disruptive to the calling
130	 * process, and is therefore disabled until someone can conceive
131	 * of a realistic scenario where it would fend off a compromise.
132	 * Race conditions concerning the temporary files can be guarded
133	 * against in other ways than masking signals (by checking stat(2)
134	 * results after creation).
135	 */
136#if 0
137	/* Unlimited resource limits. */
138	rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
139	(void)setrlimit(RLIMIT_CPU, &rlim);
140	(void)setrlimit(RLIMIT_FSIZE, &rlim);
141	(void)setrlimit(RLIMIT_STACK, &rlim);
142	(void)setrlimit(RLIMIT_DATA, &rlim);
143	(void)setrlimit(RLIMIT_RSS, &rlim);
144
145	/* Don't drop core (not really necessary, but GP's). */
146	rlim.rlim_cur = rlim.rlim_max = 0;
147	(void)setrlimit(RLIMIT_CORE, &rlim);
148
149	/* Turn off signals. */
150	(void)signal(SIGALRM, SIG_IGN);
151	(void)signal(SIGHUP, SIG_IGN);
152	(void)signal(SIGINT, SIG_IGN);
153	(void)signal(SIGPIPE, SIG_IGN);
154	(void)signal(SIGQUIT, SIG_IGN);
155	(void)signal(SIGTERM, SIG_IGN);
156	(void)signal(SIGCONT, pw_cont);
157
158	/* Create with exact permissions. */
159	(void)umask(0);
160#endif
161	initialized = 1;
162	return (0);
163}
164
165/*
166 * Lock the master password file.
167 */
168int
169pw_lock(void)
170{
171
172	if (*masterpasswd == '\0')
173		return (-1);
174
175	/*
176	 * If the master password file doesn't exist, the system is hosed.
177	 * Might as well try to build one.  Set the close-on-exec bit so
178	 * that users can't get at the encrypted passwords while editing.
179	 * Open should allow flock'ing the file; see 4.4BSD.	XXX
180	 */
181	for (;;) {
182		struct stat st;
183
184		lockfd = open(masterpasswd, O_RDONLY, 0);
185		if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
186			err(1, "%s", masterpasswd);
187		/* XXX vulnerable to race conditions */
188		if (flock(lockfd, LOCK_EX|LOCK_NB))
189			errx(1, "the password db file is busy");
190
191		/*
192		 * If the password file was replaced while we were trying to
193		 * get the lock, our hardlink count will be 0 and we have to
194		 * close and retry.
195		 */
196		if (fstat(lockfd, &st) < 0)
197			errx(1, "fstat() failed");
198		if (st.st_nlink != 0)
199			break;
200		close(lockfd);
201		lockfd = -1;
202	}
203	return (lockfd);
204}
205
206/*
207 * Create and open a presumably safe temp file for editing the password
208 * data, and copy the master password file into it.
209 */
210int
211pw_tmp(int mfd)
212{
213	char buf[8192];
214	ssize_t nr, nw;
215	const char *p;
216	int tfd;
217
218	if (*masterpasswd == '\0')
219		return (-1);
220	if ((p = strrchr(masterpasswd, '/')))
221		++p;
222	else
223		p = masterpasswd;
224	if (snprintf(tempname, sizeof tempname, "%.*spw.XXXXXX",
225		(int)(p - masterpasswd), masterpasswd) >= sizeof tempname) {
226		errno = ENAMETOOLONG;
227		return (-1);
228	}
229	if ((tfd = mkstemp(tempname)) == -1)
230		return (-1);
231	if (mfd != -1) {
232		while ((nr = read(mfd, buf, sizeof buf)) > 0)
233			if ((nw = write(tfd, buf, nr)) != nr)
234				break;
235		if (nr != 0) {
236			unlink(tempname);
237			*tempname = '\0';
238			close(tfd);
239			return (-1);
240		}
241	}
242	return (tfd);
243}
244
245/*
246 * Regenerate the password database.
247 */
248int
249pw_mkdb(const char *user)
250{
251	int pstat;
252	pid_t pid;
253
254	(void)fflush(stderr);
255	switch ((pid = fork())) {
256	case -1:
257		return (-1);
258	case 0:
259		/* child */
260		if (user == NULL)
261			execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
262			    "-d", passwd_dir, tempname, NULL);
263		else
264			execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
265			    "-d", passwd_dir, "-u", user, tempname, NULL);
266		_exit(1);
267	default:
268		/* parent */
269		break;
270	}
271	if (waitpid(pid, &pstat, 0) == -1)
272		return (-1);
273	if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
274		return (0);
275	errno = 0;
276	return (-1);
277}
278
279/*
280 * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
281 * if it was not.
282 */
283int
284pw_edit(int notsetuid)
285{
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	switch ((editpid = fork())) {
295	case -1:
296		return (-1);
297	case 0:
298		/* child */
299		if (notsetuid) {
300			(void)setgid(getgid());
301			(void)setuid(getuid());
302		}
303		errno = 0;
304		execlp(editor, basename(editor), tempname, NULL);
305		_exit(errno);
306	default:
307		/* parent */
308		break;
309	}
310	for (;;) {
311		editpid = waitpid(editpid, &pstat, WUNTRACED);
312		if (editpid == -1) {
313			unlink(tempname);
314			return (-1);
315		} else if (WIFSTOPPED(pstat)) {
316			raise(WSTOPSIG(pstat));
317		} else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
318			editpid = -1;
319			break;
320		} else {
321			unlink(tempname);
322			*tempname = '\0';
323			editpid = -1;
324			return (-1);
325		}
326	}
327	if (stat(tempname, &st2) == -1)
328		return (-1);
329	return (st1.st_mtime != st2.st_mtime);
330}
331
332/*
333 * Clean up.  Preserve errno for the caller's convenience.
334 */
335void
336pw_fini(void)
337{
338	int serrno, status;
339
340	if (!initialized)
341		return;
342	initialized = 0;
343	serrno = errno;
344	if (editpid != -1) {
345		kill(editpid, SIGTERM);
346		kill(editpid, SIGCONT);
347		waitpid(editpid, &status, 0);
348		editpid = -1;
349	}
350	if (*tempname != '\0') {
351		unlink(tempname);
352		*tempname = '\0';
353	}
354	if (lockfd != -1)
355		close(lockfd);
356	errno = serrno;
357}
358
359/*
360 * Compares two struct pwds.
361 */
362int
363pw_equal(struct passwd *pw1, struct passwd *pw2)
364{
365	return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
366	    pw1->pw_uid == pw2->pw_uid &&
367	    pw1->pw_gid == pw2->pw_gid &&
368	    strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
369	    pw1->pw_change == pw2->pw_change &&
370	    pw1->pw_expire == pw2->pw_expire &&
371	    strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
372	    strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
373	    strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
374}
375
376/*
377 * Make a passwd line out of a struct passwd.
378 */
379char *
380pw_make(struct passwd *pw)
381{
382	char *line;
383
384	asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
385	    pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
386	    pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
387	    pw->pw_gecos, pw->pw_dir, pw->pw_shell);
388	return line;
389}
390
391/*
392 * Copy password file from one descriptor to another, replacing or adding
393 * a single record on the way.
394 */
395int
396pw_copy(int ffd, int tfd, struct passwd *pw, struct passwd *old_pw)
397{
398	char buf[8192], *end, *line, *p, *q, *r, t;
399	struct passwd *fpw;
400	ssize_t len;
401	int eof;
402
403	if ((line = pw_make(pw)) == NULL)
404		return (-1);
405
406	eof = 0;
407	len = 0;
408	p = q = end = buf;
409	for (;;) {
410		/* find the end of the current line */
411		for (p = q; q < end && *q != '\0'; ++q)
412			if (*q == '\n')
413				break;
414
415		/* if we don't have a complete line, fill up the buffer */
416		if (q >= end) {
417			if (eof)
418				break;
419			if (q - p >= sizeof buf) {
420				warnx("passwd line too long");
421				errno = EINVAL; /* hack */
422				goto err;
423			}
424			if (p < end) {
425				q = memmove(buf, p, end - p);
426				end -= p - buf;
427			} else {
428				p = q = end = buf;
429			}
430			len = read(ffd, end, sizeof buf - (end - buf));
431			if (len == -1)
432				goto err;
433			if (len == 0 && p == buf)
434				break;
435			end += len;
436			len = end - buf;
437			if (len < sizeof buf) {
438				eof = 1;
439				if (len > 0 && buf[len - 1] != '\n')
440					++len, *end++ = '\n';
441			}
442			continue;
443		}
444
445		/* is it a blank line or a comment? */
446		for (r = p; r < q && isspace(*r); ++r)
447			/* nothing */ ;
448		if (r == q || *r == '#') {
449			/* yep */
450			if (write(tfd, p, q - p + 1) != q - p + 1)
451				goto err;
452			++q;
453			continue;
454		}
455
456		/* is it the one we're looking for? */
457		t = *q;
458		*q = '\0';
459		fpw = pw_scan(r, PWSCAN_MASTER);
460		*q = t;
461		if (old_pw == NULL || !pw_equal(pw, old_pw)) {
462			/* nope */
463			free(fpw);
464			if (write(tfd, p, q - p + 1) != q - p + 1)
465				goto err;
466			++q;
467			continue;
468		}
469		free(fpw);
470
471		/* it is, replace it */
472		len = strlen(line);
473		if (write(tfd, line, len) != len)
474			goto err;
475
476		/* we're done, just copy the rest over */
477		for (;;) {
478			if (write(tfd, q, end - q) != end - q)
479				goto err;
480			q = buf;
481			len = read(ffd, buf, sizeof buf);
482			if (len == 0)
483				break;
484			if (len == -1)
485				goto err;
486			end = buf + len;
487		}
488		goto done;
489	}
490
491	/* if we got here, we have a new entry */
492	len = strlen(line);
493	if (write(tfd, line, len) != len)
494		goto err;
495 done:
496	free(line);
497	return (0);
498 err:
499	free(line);
500	return (-1);
501}
502
503/*
504 * Return the current value of tempname.
505 */
506const char *
507pw_tempname(void)
508{
509
510	return (tempname);
511}
512
513/*
514 * Duplicate a struct passwd.
515 */
516struct passwd *
517pw_dup(struct passwd *pw)
518{
519	struct passwd *npw;
520	size_t len;
521
522	len = sizeof *npw +
523	    (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) +
524	    (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) +
525	    (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) +
526	    (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) +
527	    (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) +
528	    (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0);
529	if ((npw = malloc(len)) == NULL)
530		return (NULL);
531	memcpy(npw, pw, sizeof *npw);
532	len = sizeof *npw;
533	if (pw->pw_name) {
534		npw->pw_name = ((char *)npw) + len;
535		len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1;
536	}
537	if (pw->pw_passwd) {
538		npw->pw_passwd = ((char *)npw) + len;
539		len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1;
540	}
541	if (pw->pw_class) {
542		npw->pw_class = ((char *)npw) + len;
543		len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1;
544	}
545	if (pw->pw_gecos) {
546		npw->pw_gecos = ((char *)npw) + len;
547		len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1;
548	}
549	if (pw->pw_dir) {
550		npw->pw_dir = ((char *)npw) + len;
551		len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1;
552	}
553	if (pw->pw_shell) {
554		npw->pw_shell = ((char *)npw) + len;
555		len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1;
556	}
557	return (npw);
558}
559
560#include "pw_scan.h"
561
562/*
563 * Wrapper around an internal libc function
564 */
565struct passwd *
566pw_scan(const char *line, int flags)
567{
568	struct passwd pw, *ret;
569	char *bp;
570
571	if ((bp = strdup(line)) == NULL)
572		return (NULL);
573	if (!__pw_scan(bp, &pw, flags)) {
574		free(bp);
575		return (NULL);
576	}
577	ret = pw_dup(&pw);
578	free(bp);
579	return (ret);
580}
581