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 * 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 */
36
37#ifndef lint
38#if 0
39static const char sccsid[] = "@(#)pw_util.c	8.3 (Berkeley) 4/2/94";
40#endif
41static const char rcsid[] =
42  "$FreeBSD$";
43#endif /* not lint */
44
45/*
46 * This file is used by all the "password" programs; vipw(8), chpass(1),
47 * and passwd(1).
48 */
49
50#include <sys/param.h>
51#include <sys/errno.h>
52#include <sys/time.h>
53#include <sys/resource.h>
54#include <sys/stat.h>
55#include <sys/wait.h>
56
57#include <ctype.h>
58#include <err.h>
59#include <fcntl.h>
60#include <inttypes.h>
61#include <libgen.h>
62#include <paths.h>
63#include <pwd.h>
64#include <signal.h>
65#include <stdio.h>
66#include <stdlib.h>
67#include <string.h>
68#include <unistd.h>
69
70#include "libutil.h"
71
72static pid_t editpid = -1;
73static int lockfd = -1;
74static char masterpasswd[PATH_MAX];
75static char passwd_dir[PATH_MAX];
76static char tempname[PATH_MAX];
77static int initialized;
78
79#if 0
80void
81pw_cont(int sig)
82{
83
84	if (editpid != -1)
85		kill(editpid, sig);
86}
87#endif
88
89/*
90 * Initialize statics and set limits, signals & umask to try to avoid
91 * interruptions, crashes etc. that might expose passord data.
92 */
93int
94pw_init(const char *dir, const char *master)
95{
96#if 0
97	struct rlimit rlim;
98#endif
99
100	if (dir == NULL) {
101		strcpy(passwd_dir, _PATH_ETC);
102	} else {
103		if (strlen(dir) >= sizeof(passwd_dir)) {
104			errno = ENAMETOOLONG;
105			return (-1);
106		}
107		strcpy(passwd_dir, dir);
108	}
109
110	if (master == NULL) {
111		if (dir == NULL) {
112			strcpy(masterpasswd, _PATH_MASTERPASSWD);
113		} else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
114		    passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
115			errno = ENAMETOOLONG;
116			return (-1);
117		}
118	} else {
119		if (strlen(master) >= sizeof(masterpasswd)) {
120			errno = ENAMETOOLONG;
121			return (-1);
122		}
123		strcpy(masterpasswd, master);
124	}
125
126	/*
127	 * The code that follows is extremely disruptive to the calling
128	 * process, and is therefore disabled until someone can conceive
129	 * of a realistic scenario where it would fend off a compromise.
130	 * Race conditions concerning the temporary files can be guarded
131	 * against in other ways than masking signals (by checking stat(2)
132	 * results after creation).
133	 */
134#if 0
135	/* Unlimited resource limits. */
136	rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
137	(void)setrlimit(RLIMIT_CPU, &rlim);
138	(void)setrlimit(RLIMIT_FSIZE, &rlim);
139	(void)setrlimit(RLIMIT_STACK, &rlim);
140	(void)setrlimit(RLIMIT_DATA, &rlim);
141	(void)setrlimit(RLIMIT_RSS, &rlim);
142
143	/* Don't drop core (not really necessary, but GP's). */
144	rlim.rlim_cur = rlim.rlim_max = 0;
145	(void)setrlimit(RLIMIT_CORE, &rlim);
146
147	/* Turn off signals. */
148	(void)signal(SIGALRM, SIG_IGN);
149	(void)signal(SIGHUP, SIG_IGN);
150	(void)signal(SIGINT, SIG_IGN);
151	(void)signal(SIGPIPE, SIG_IGN);
152	(void)signal(SIGQUIT, SIG_IGN);
153	(void)signal(SIGTERM, SIG_IGN);
154	(void)signal(SIGCONT, pw_cont);
155
156	/* Create with exact permissions. */
157	(void)umask(0);
158#endif
159	initialized = 1;
160	return (0);
161}
162
163/*
164 * Lock the master password file.
165 */
166int
167pw_lock(void)
168{
169
170	if (*masterpasswd == '\0')
171		return (-1);
172
173	/*
174	 * If the master password file doesn't exist, the system is hosed.
175	 * Might as well try to build one.  Set the close-on-exec bit so
176	 * that users can't get at the encrypted passwords while editing.
177	 * Open should allow flock'ing the file; see 4.4BSD.	XXX
178	 */
179	for (;;) {
180		struct stat st;
181
182		lockfd = open(masterpasswd, O_RDONLY, 0);
183		if (lockfd < 0 || fcntl(lockfd, F_SETFD, 1) == -1)
184			err(1, "%s", masterpasswd);
185		/* XXX vulnerable to race conditions */
186		if (flock(lockfd, LOCK_EX|LOCK_NB) == -1) {
187			if (errno == EWOULDBLOCK) {
188				errx(1, "the password db file is busy");
189			} else {
190				err(1, "could not lock the passwd file: ");
191			}
192		}
193
194		/*
195		 * If the password file was replaced while we were trying to
196		 * get the lock, our hardlink count will be 0 and we have to
197		 * close and retry.
198		 */
199		if (fstat(lockfd, &st) == -1)
200			err(1, "fstat() failed: ");
201		if (st.st_nlink != 0)
202			break;
203		close(lockfd);
204		lockfd = -1;
205	}
206	return (lockfd);
207}
208
209/*
210 * Create and open a presumably safe temp file for editing the password
211 * data, and copy the master password file into it.
212 */
213int
214pw_tmp(int mfd)
215{
216	char buf[8192];
217	ssize_t nr;
218	const char *p;
219	int tfd;
220
221	if (*masterpasswd == '\0')
222		return (-1);
223	if ((p = strrchr(masterpasswd, '/')))
224		++p;
225	else
226		p = masterpasswd;
227	if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
228		(int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
229		errno = ENAMETOOLONG;
230		return (-1);
231	}
232	if ((tfd = mkstemp(tempname)) == -1)
233		return (-1);
234	if (mfd != -1) {
235		while ((nr = read(mfd, buf, sizeof(buf))) > 0)
236			if (write(tfd, buf, (size_t)nr) != nr)
237				break;
238		if (nr != 0) {
239			unlink(tempname);
240			*tempname = '\0';
241			close(tfd);
242			return (-1);
243		}
244	}
245	return (tfd);
246}
247
248/*
249 * Regenerate the password database.
250 */
251int
252pw_mkdb(const char *user)
253{
254	int pstat;
255	pid_t pid;
256
257	(void)fflush(stderr);
258	switch ((pid = fork())) {
259	case -1:
260		return (-1);
261	case 0:
262		/* child */
263		if (user == NULL)
264			execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
265			    "-d", passwd_dir, tempname, (char *)NULL);
266		else
267			execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
268			    "-d", passwd_dir, "-u", user, tempname,
269			    (char *)NULL);
270		_exit(1);
271		/* NOTREACHED */
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, nsigset;
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(&nsigset);
307	sigaddset(&nsigset, SIGCHLD);
308	sigprocmask(SIG_BLOCK, &nsigset, &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, (char *)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(const struct passwd *pw1, const 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(const 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 * Make a passwd line (in v7 format) out of a struct passwd
414 */
415char *
416pw_make_v7(const struct passwd *pw)
417{
418	char *line;
419
420	asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
421	    (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
422	    pw->pw_gecos, pw->pw_dir, pw->pw_shell);
423	return (line);
424}
425
426/*
427 * Copy password file from one descriptor to another, replacing, deleting
428 * or adding a single record on the way.
429 */
430int
431pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
432{
433	char buf[8192], *end, *line, *p, *q, *r, t;
434	struct passwd *fpw;
435	const struct passwd *spw;
436	size_t len;
437	int eof, readlen;
438
439	if (old_pw == NULL && pw == NULL)
440			return (-1);
441
442	spw = old_pw;
443	/* deleting a user */
444	if (pw == NULL) {
445		line = NULL;
446	} else {
447		if ((line = pw_make(pw)) == NULL)
448			return (-1);
449	}
450
451	/* adding a user */
452	if (spw == NULL)
453		spw = pw;
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			if ((size_t)(q - p) >= sizeof(buf)) {
469				warnx("passwd line too long");
470				errno = EINVAL; /* hack */
471				goto err;
472			}
473			if (p < end) {
474				q = memmove(buf, p, end - p);
475				end -= p - buf;
476			} else {
477				p = q = end = buf;
478			}
479			readlen = read(ffd, end, sizeof(buf) - (end - buf));
480			if (readlen == -1)
481				goto err;
482			else
483				len = (size_t)readlen;
484			if (len == 0 && p == buf)
485				break;
486			end += len;
487			len = end - buf;
488			if (len < (ssize_t)sizeof(buf)) {
489				eof = 1;
490				if (len > 0 && buf[len - 1] != '\n')
491					++len, *end++ = '\n';
492			}
493			continue;
494		}
495
496		/* is it a blank line or a comment? */
497		for (r = p; r < q && isspace(*r); ++r)
498			/* nothing */ ;
499		if (r == q || *r == '#') {
500			/* yep */
501			if (write(tfd, p, q - p + 1) != q - p + 1)
502				goto err;
503			++q;
504			continue;
505		}
506
507		/* is it the one we're looking for? */
508
509		t = *q;
510		*q = '\0';
511
512		fpw = pw_scan(r, PWSCAN_MASTER);
513
514		/*
515		 * fpw is either the struct passwd for the current line,
516		 * or NULL if the line is malformed.
517		 */
518
519		*q = t;
520		if (fpw == NULL || strcmp(fpw->pw_name, spw->pw_name) != 0) {
521			/* nope */
522			if (fpw != NULL)
523				free(fpw);
524			if (write(tfd, p, q - p + 1) != q - p + 1)
525				goto err;
526			++q;
527			continue;
528		}
529		if (old_pw && !pw_equal(fpw, old_pw)) {
530			warnx("entry inconsistent");
531			free(fpw);
532			errno = EINVAL; /* hack */
533			goto err;
534		}
535		free(fpw);
536
537		/* it is, replace or remove it */
538		if (line != NULL) {
539			len = strlen(line);
540			if (write(tfd, line, len) != (int)len)
541				goto err;
542		} else {
543			/* when removed, avoid the \n */
544			q++;
545		}
546		/* we're done, just copy the rest over */
547		for (;;) {
548			if (write(tfd, q, end - q) != end - q)
549				goto err;
550			q = buf;
551			readlen = read(ffd, buf, sizeof(buf));
552			if (readlen == 0)
553				break;
554			else
555				len = (size_t)readlen;
556			if (readlen == -1)
557				goto err;
558			end = buf + len;
559		}
560		goto done;
561	}
562
563	/* if we got here, we didn't find the old entry */
564	if (line == NULL) {
565		errno = ENOENT;
566		goto err;
567	}
568	len = strlen(line);
569	if ((size_t)write(tfd, line, len) != len ||
570	    write(tfd, "\n", 1) != 1)
571		goto err;
572 done:
573	if (line != NULL)
574		free(line);
575	return (0);
576 err:
577	if (line != NULL)
578		free(line);
579	return (-1);
580}
581
582/*
583 * Return the current value of tempname.
584 */
585const char *
586pw_tempname(void)
587{
588
589	return (tempname);
590}
591
592/*
593 * Duplicate a struct passwd.
594 */
595struct passwd *
596pw_dup(const struct passwd *pw)
597{
598	char *dst;
599	struct passwd *npw;
600	ssize_t len;
601
602	len = sizeof(*npw);
603	if (pw->pw_name != NULL)
604		len += strlen(pw->pw_name) + 1;
605	if (pw->pw_passwd != NULL)
606		len += strlen(pw->pw_passwd) + 1;
607	if (pw->pw_class != NULL)
608		len += strlen(pw->pw_class) + 1;
609	if (pw->pw_gecos != NULL)
610		len += strlen(pw->pw_gecos) + 1;
611	if (pw->pw_dir != NULL)
612		len += strlen(pw->pw_dir) + 1;
613	if (pw->pw_shell != NULL)
614		len += strlen(pw->pw_shell) + 1;
615	if ((npw = malloc((size_t)len)) == NULL)
616		return (NULL);
617	memcpy(npw, pw, sizeof(*npw));
618	dst = (char *)npw + sizeof(*npw);
619	if (pw->pw_name != NULL) {
620		npw->pw_name = dst;
621		dst = stpcpy(npw->pw_name, pw->pw_name) + 1;
622	}
623	if (pw->pw_passwd != NULL) {
624		npw->pw_passwd = dst;
625		dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1;
626	}
627	if (pw->pw_class != NULL) {
628		npw->pw_class = dst;
629		dst = stpcpy(npw->pw_class, pw->pw_class) + 1;
630	}
631	if (pw->pw_gecos != NULL) {
632		npw->pw_gecos = dst;
633		dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1;
634	}
635	if (pw->pw_dir != NULL) {
636		npw->pw_dir = dst;
637		dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1;
638	}
639	if (pw->pw_shell != NULL) {
640		npw->pw_shell = dst;
641		dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1;
642	}
643	return (npw);
644}
645
646#include "pw_scan.h"
647
648/*
649 * Wrapper around an internal libc function
650 */
651struct passwd *
652pw_scan(const char *line, int flags)
653{
654	struct passwd pw, *ret;
655	char *bp;
656
657	if ((bp = strdup(line)) == NULL)
658		return (NULL);
659	if (!__pw_scan(bp, &pw, flags)) {
660		free(bp);
661		return (NULL);
662	}
663	ret = pw_dup(&pw);
664	free(bp);
665	return (ret);
666}
667