pw_util.c revision 116344 
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 116344 2003-06-14 18:42:37Z markm $";
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 <ctype.h>
62#include <err.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) == -1) {
189			if (errno == EWOULDBLOCK) {
190				errx(1, "the password db file is busy");
191			} else {
192				err(1, "could not lock the passwd file: ");
193			}
194		}
195
196		/*
197		 * If the password file was replaced while we were trying to
198		 * get the lock, our hardlink count will be 0 and we have to
199		 * close and retry.
200		 */
201		if (fstat(lockfd, &st) == -1)
202			err(1, "fstat() failed: ");
203		if (st.st_nlink != 0)
204			break;
205		close(lockfd);
206		lockfd = -1;
207	}
208	return (lockfd);
209}
210
211/*
212 * Create and open a presumably safe temp file for editing the password
213 * data, and copy the master password file into it.
214 */
215int
216pw_tmp(int mfd)
217{
218	char buf[8192];
219	ssize_t nr, nw;
220	const char *p;
221	int tfd;
222
223	if (*masterpasswd == '\0')
224		return (-1);
225	if ((p = strrchr(masterpasswd, '/')))
226		++p;
227	else
228		p = masterpasswd;
229	if (snprintf(tempname, sizeof tempname, "%.*spw.XXXXXX",
230		(int)(p - masterpasswd), masterpasswd) >= sizeof tempname) {
231		errno = ENAMETOOLONG;
232		return (-1);
233	}
234	if ((tfd = mkstemp(tempname)) == -1)
235		return (-1);
236	if (mfd != -1) {
237		while ((nr = read(mfd, buf, sizeof buf)) > 0)
238			if ((nw = write(tfd, buf, nr)) != nr)
239				break;
240		if (nr != 0) {
241			unlink(tempname);
242			*tempname = '\0';
243			close(tfd);
244			return (-1);
245		}
246	}
247	return (tfd);
248}
249
250/*
251 * Regenerate the password database.
252 */
253int
254pw_mkdb(const char *user)
255{
256	int pstat;
257	pid_t pid;
258
259	(void)fflush(stderr);
260	switch ((pid = fork())) {
261	case -1:
262		return (-1);
263	case 0:
264		/* child */
265		if (user == NULL)
266			execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
267			    "-d", passwd_dir, tempname, NULL);
268		else
269			execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
270			    "-d", passwd_dir, "-u", user, tempname, NULL);
271		_exit(1);
272	default:
273		/* parent */
274		break;
275	}
276	if (waitpid(pid, &pstat, 0) == -1)
277		return (-1);
278	if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
279		return (0);
280	errno = 0;
281	return (-1);
282}
283
284/*
285 * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
286 * if it was not.
287 */
288int
289pw_edit(int notsetuid)
290{
291	struct sigaction sa, sa_int, sa_quit;
292	sigset_t oldsigset, sigset;
293	struct stat st1, st2;
294	const char *editor;
295	int pstat;
296
297	if ((editor = getenv("EDITOR")) == NULL)
298		editor = _PATH_VI;
299	if (stat(tempname, &st1) == -1)
300		return (-1);
301	sa.sa_handler = SIG_IGN;
302	sigemptyset(&sa.sa_mask);
303	sa.sa_flags = 0;
304	sigaction(SIGINT, &sa, &sa_int);
305	sigaction(SIGQUIT, &sa, &sa_quit);
306	sigemptyset(&sigset);
307	sigaddset(&sigset, SIGCHLD);
308	sigprocmask(SIG_BLOCK, &sigset, &oldsigset);
309	switch ((editpid = fork())) {
310	case -1:
311		return (-1);
312	case 0:
313		sigaction(SIGINT, &sa_int, NULL);
314		sigaction(SIGQUIT, &sa_quit, NULL);
315		sigprocmask(SIG_SETMASK, &oldsigset, NULL);
316		if (notsetuid) {
317			(void)setgid(getgid());
318			(void)setuid(getuid());
319		}
320		errno = 0;
321		execlp(editor, basename(editor), tempname, NULL);
322		_exit(errno);
323	default:
324		/* parent */
325		break;
326	}
327	for (;;) {
328		if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
329			if (errno == EINTR)
330				continue;
331			unlink(tempname);
332			editpid = -1;
333			break;
334		} else if (WIFSTOPPED(pstat)) {
335			raise(WSTOPSIG(pstat));
336		} else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0) {
337			editpid = -1;
338			break;
339		} else {
340			unlink(tempname);
341			editpid = -1;
342			break;
343		}
344	}
345	sigaction(SIGINT, &sa_int, NULL);
346	sigaction(SIGQUIT, &sa_quit, NULL);
347	sigprocmask(SIG_SETMASK, &oldsigset, NULL);
348	if (stat(tempname, &st2) == -1)
349		return (-1);
350	return (st1.st_mtime != st2.st_mtime);
351}
352
353/*
354 * Clean up.  Preserve errno for the caller's convenience.
355 */
356void
357pw_fini(void)
358{
359	int serrno, status;
360
361	if (!initialized)
362		return;
363	initialized = 0;
364	serrno = errno;
365	if (editpid != -1) {
366		kill(editpid, SIGTERM);
367		kill(editpid, SIGCONT);
368		waitpid(editpid, &status, 0);
369		editpid = -1;
370	}
371	if (*tempname != '\0') {
372		unlink(tempname);
373		*tempname = '\0';
374	}
375	if (lockfd != -1)
376		close(lockfd);
377	errno = serrno;
378}
379
380/*
381 * Compares two struct pwds.
382 */
383int
384pw_equal(struct passwd *pw1, struct passwd *pw2)
385{
386	return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
387	    pw1->pw_uid == pw2->pw_uid &&
388	    pw1->pw_gid == pw2->pw_gid &&
389	    strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
390	    pw1->pw_change == pw2->pw_change &&
391	    pw1->pw_expire == pw2->pw_expire &&
392	    strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
393	    strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
394	    strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
395}
396
397/*
398 * Make a passwd line out of a struct passwd.
399 */
400char *
401pw_make(struct passwd *pw)
402{
403	char *line;
404
405	asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
406	    pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
407	    pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
408	    pw->pw_gecos, pw->pw_dir, pw->pw_shell);
409	return line;
410}
411
412/*
413 * Copy password file from one descriptor to another, replacing or adding
414 * a single record on the way.
415 */
416int
417pw_copy(int ffd, int tfd, struct passwd *pw, struct passwd *old_pw)
418{
419	char buf[8192], *end, *line, *p, *q, *r, t;
420	struct passwd *fpw;
421	ssize_t len;
422	int eof;
423
424	if ((line = pw_make(pw)) == NULL)
425		return (-1);
426
427	eof = 0;
428	len = 0;
429	p = q = end = buf;
430	for (;;) {
431		/* find the end of the current line */
432		for (p = q; q < end && *q != '\0'; ++q)
433			if (*q == '\n')
434				break;
435
436		/* if we don't have a complete line, fill up the buffer */
437		if (q >= end) {
438			if (eof)
439				break;
440			if (q - p >= sizeof buf) {
441				warnx("passwd line too long");
442				errno = EINVAL; /* hack */
443				goto err;
444			}
445			if (p < end) {
446				q = memmove(buf, p, end - p);
447				end -= p - buf;
448			} else {
449				p = q = end = buf;
450			}
451			len = read(ffd, end, sizeof buf - (end - buf));
452			if (len == -1)
453				goto err;
454			if (len == 0 && p == buf)
455				break;
456			end += len;
457			len = end - buf;
458			if (len < sizeof buf) {
459				eof = 1;
460				if (len > 0 && buf[len - 1] != '\n')
461					++len, *end++ = '\n';
462			}
463			continue;
464		}
465
466		/* is it a blank line or a comment? */
467		for (r = p; r < q && isspace(*r); ++r)
468			/* nothing */ ;
469		if (r == q || *r == '#') {
470			/* yep */
471			if (write(tfd, p, q - p + 1) != q - p + 1)
472				goto err;
473			++q;
474			continue;
475		}
476
477		/* is it the one we're looking for? */
478		t = *q;
479		*q = '\0';
480		fpw = pw_scan(r, PWSCAN_MASTER);
481		*q = t;
482		if (strcmp(fpw->pw_name, pw->pw_name) != 0) {
483			/* nope */
484			free(fpw);
485			if (write(tfd, p, q - p + 1) != q - p + 1)
486				goto err;
487			++q;
488			continue;
489		}
490		if (old_pw && !pw_equal(fpw, old_pw)) {
491			warnx("entry inconsistent");
492			free(fpw);
493			errno = EINVAL; /* hack */
494			goto err;
495		}
496		free(fpw);
497
498		/* it is, replace it */
499		len = strlen(line);
500		if (write(tfd, line, len) != len)
501			goto err;
502
503		/* we're done, just copy the rest over */
504		for (;;) {
505			if (write(tfd, q, end - q) != end - q)
506				goto err;
507			q = buf;
508			len = read(ffd, buf, sizeof buf);
509			if (len == 0)
510				break;
511			if (len == -1)
512				goto err;
513			end = buf + len;
514		}
515		goto done;
516	}
517
518	/* if we got here, we have a new entry */
519	len = strlen(line);
520	if (write(tfd, line, len) != len ||
521	    write(tfd, "\n", 1) != 1)
522		goto err;
523 done:
524	free(line);
525	return (0);
526 err:
527	free(line);
528	return (-1);
529}
530
531/*
532 * Return the current value of tempname.
533 */
534const char *
535pw_tempname(void)
536{
537
538	return (tempname);
539}
540
541/*
542 * Duplicate a struct passwd.
543 */
544struct passwd *
545pw_dup(struct passwd *pw)
546{
547	struct passwd *npw;
548	size_t len;
549
550	len = sizeof *npw +
551	    (pw->pw_name ? strlen(pw->pw_name) + 1 : 0) +
552	    (pw->pw_passwd ? strlen(pw->pw_passwd) + 1 : 0) +
553	    (pw->pw_class ? strlen(pw->pw_class) + 1 : 0) +
554	    (pw->pw_gecos ? strlen(pw->pw_gecos) + 1 : 0) +
555	    (pw->pw_dir ? strlen(pw->pw_dir) + 1 : 0) +
556	    (pw->pw_shell ? strlen(pw->pw_shell) + 1 : 0);
557	if ((npw = malloc(len)) == NULL)
558		return (NULL);
559	memcpy(npw, pw, sizeof *npw);
560	len = sizeof *npw;
561	if (pw->pw_name) {
562		npw->pw_name = ((char *)npw) + len;
563		len += sprintf(npw->pw_name, "%s", pw->pw_name) + 1;
564	}
565	if (pw->pw_passwd) {
566		npw->pw_passwd = ((char *)npw) + len;
567		len += sprintf(npw->pw_passwd, "%s", pw->pw_passwd) + 1;
568	}
569	if (pw->pw_class) {
570		npw->pw_class = ((char *)npw) + len;
571		len += sprintf(npw->pw_class, "%s", pw->pw_class) + 1;
572	}
573	if (pw->pw_gecos) {
574		npw->pw_gecos = ((char *)npw) + len;
575		len += sprintf(npw->pw_gecos, "%s", pw->pw_gecos) + 1;
576	}
577	if (pw->pw_dir) {
578		npw->pw_dir = ((char *)npw) + len;
579		len += sprintf(npw->pw_dir, "%s", pw->pw_dir) + 1;
580	}
581	if (pw->pw_shell) {
582		npw->pw_shell = ((char *)npw) + len;
583		len += sprintf(npw->pw_shell, "%s", pw->pw_shell) + 1;
584	}
585	return (npw);
586}
587
588#include "pw_scan.h"
589
590/*
591 * Wrapper around an internal libc function
592 */
593struct passwd *
594pw_scan(const char *line, int flags)
595{
596	struct passwd pw, *ret;
597	char *bp;
598
599	if ((bp = strdup(line)) == NULL)
600		return (NULL);
601	if (!__pw_scan(bp, &pw, flags)) {
602		free(bp);
603		return (NULL);
604	}
605	ret = pw_dup(&pw);
606	free(bp);
607	return (ret);
608}
609