1/*--
2 * SPDX-License-Identifier: BSD-3-Clause
3 *
4 * Copyright (c) 1990, 1993, 1994
5 *	The Regents of the University of California.  All rights reserved.
6 * Copyright (c) 2002 Networks Associates Technology, Inc.
7 * All rights reserved.
8 *
9 * Portions of this software were developed for the FreeBSD Project by
10 * ThinkSec AS and NAI Labs, the Security Research Division of Network
11 * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
12 * ("CBOSS"), as part of the DARPA CHATS research program.
13 *
14 * Redistribution and use in source and binary forms, with or without
15 * modification, are permitted provided that the following conditions
16 * are met:
17 * 1. Redistributions of source code must retain the above copyright
18 *    notice, this list of conditions and the following disclaimer.
19 * 2. Redistributions in binary form must reproduce the above copyright
20 *    notice, this list of conditions and the following disclaimer in the
21 *    documentation and/or other materials provided with the distribution.
22 * 3. Neither the name of the University nor the names of its contributors
23 *    may be used to endorse or promote products derived from this software
24 *    without specific prior written permission.
25 *
26 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
27 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
30 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36 * SUCH DAMAGE.
37 */
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 <paths.h>
57#include <pwd.h>
58#include <signal.h>
59#include <stdio.h>
60#include <stdlib.h>
61#include <string.h>
62#include <unistd.h>
63
64#include "libutil.h"
65
66static pid_t editpid = -1;
67static int lockfd = -1;
68static char masterpasswd[PATH_MAX];
69static char passwd_dir[PATH_MAX];
70static char tempname[PATH_MAX];
71static int initialized;
72
73#if 0
74void
75pw_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 */
87int
88pw_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 */
160int
161pw_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 */
204int
205pw_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 = mkostemp(tempname, 0)) == -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 */
242int
243pw_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, (char *)NULL);
257		else
258			execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
259			    "-d", passwd_dir, "-u", user, tempname,
260			    (char *)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 */
279int
280pw_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			if (setgid(getgid()) == -1)
309				err(1, "setgid");
310			if (setuid(getuid()) == -1)
311				err(1, "setuid");
312		}
313		execlp(editor, editor, tempname, (char *)NULL);
314		err(1, "%s", editor);
315	default:
316		/* parent */
317		break;
318	}
319	for (;;) {
320		if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
321			if (errno == EINTR)
322				continue;
323			unlink(tempname);
324			editpid = -1;
325			break;
326		} else if (WIFSTOPPED(pstat)) {
327			raise(WSTOPSIG(pstat));
328		} else if (WIFEXITED(pstat)) {
329			if (WEXITSTATUS(pstat) != 0)
330				errx(1, "\"%s\" exited with status %d", editor, WEXITSTATUS(pstat));
331			editpid = -1;
332			break;
333		} else {
334			unlink(tempname);
335			editpid = -1;
336			break;
337		}
338	}
339	sigaction(SIGINT, &sa_int, NULL);
340	sigaction(SIGQUIT, &sa_quit, NULL);
341	sigprocmask(SIG_SETMASK, &oldsigset, NULL);
342	if (stat(tempname, &st2) == -1)
343		return (-1);
344	return (st1.st_mtim.tv_sec != st2.st_mtim.tv_sec ||
345	    st1.st_mtim.tv_nsec != st2.st_mtim.tv_nsec);
346}
347
348/*
349 * Clean up.  Preserve errno for the caller's convenience.
350 */
351void
352pw_fini(void)
353{
354	int serrno, status;
355
356	if (!initialized)
357		return;
358	initialized = 0;
359	serrno = errno;
360	if (editpid != -1) {
361		kill(editpid, SIGTERM);
362		kill(editpid, SIGCONT);
363		waitpid(editpid, &status, 0);
364		editpid = -1;
365	}
366	if (*tempname != '\0') {
367		unlink(tempname);
368		*tempname = '\0';
369	}
370	if (lockfd != -1)
371		close(lockfd);
372	errno = serrno;
373}
374
375/*
376 * Compares two struct pwds.
377 */
378int
379pw_equal(const struct passwd *pw1, const struct passwd *pw2)
380{
381	return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
382	    pw1->pw_uid == pw2->pw_uid &&
383	    pw1->pw_gid == pw2->pw_gid &&
384	    strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
385	    pw1->pw_change == pw2->pw_change &&
386	    pw1->pw_expire == pw2->pw_expire &&
387	    strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
388	    strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
389	    strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
390}
391
392/*
393 * Make a passwd line out of a struct passwd.
394 */
395char *
396pw_make(const struct passwd *pw)
397{
398	char *line;
399
400	asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
401	    pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
402	    pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
403	    pw->pw_gecos, pw->pw_dir, pw->pw_shell);
404	return (line);
405}
406
407/*
408 * Make a passwd line (in v7 format) out of a struct passwd
409 */
410char *
411pw_make_v7(const struct passwd *pw)
412{
413	char *line;
414
415	asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
416	    (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
417	    pw->pw_gecos, pw->pw_dir, pw->pw_shell);
418	return (line);
419}
420
421/*
422 * Copy password file from one descriptor to another, replacing, deleting
423 * or adding a single record on the way.
424 */
425int
426pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
427{
428	char *buf, *end, *line, *p, *q, *r, *tmp;
429	struct passwd *fpw;
430	const struct passwd *spw;
431	size_t len, size;
432	int eof, readlen;
433	char t;
434
435	if (old_pw == NULL && pw == NULL)
436			return (-1);
437
438	spw = old_pw;
439	/* deleting a user */
440	if (pw == NULL) {
441		line = NULL;
442	} else {
443		if ((line = pw_make(pw)) == NULL)
444			return (-1);
445	}
446
447	/* adding a user */
448	if (spw == NULL)
449		spw = pw;
450
451	/* initialize the buffer */
452	if ((buf = malloc(size = 1024)) == NULL)
453		goto err;
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			while ((size_t)(q - p) >= size) {
469				if ((tmp = reallocarray(buf, 2, size)) == NULL) {
470					warnx("passwd line too long");
471					goto err;
472				}
473				p = tmp + (p - buf);
474				q = tmp + (q - buf);
475				end = tmp + (end - buf);
476				buf = tmp;
477				size = size * 2;
478			}
479			if (p < end) {
480				q = memmove(buf, p, end - p);
481				end -= p - buf;
482			} else {
483				p = q = end = buf;
484			}
485			readlen = read(ffd, end, size - (end - buf));
486			if (readlen == -1)
487				goto err;
488			else
489				len = (size_t)readlen;
490			if (len == 0 && p == buf)
491				break;
492			end += len;
493			len = end - buf;
494			if (len < size) {
495				eof = 1;
496				if (len > 0 && buf[len - 1] != '\n')
497					++len, *end++ = '\n';
498			}
499			continue;
500		}
501
502		/* is it a blank line or a comment? */
503		for (r = p; r < q && isspace(*r); ++r)
504			/* nothing */ ;
505		if (r == q || *r == '#') {
506			/* yep */
507			if (write(tfd, p, q - p + 1) != q - p + 1)
508				goto err;
509			++q;
510			continue;
511		}
512
513		/* is it the one we're looking for? */
514
515		t = *q;
516		*q = '\0';
517
518		fpw = pw_scan(r, PWSCAN_MASTER);
519
520		/*
521		 * fpw is either the struct passwd for the current line,
522		 * or NULL if the line is malformed.
523		 */
524
525		*q = t;
526		if (fpw == NULL || strcmp(fpw->pw_name, spw->pw_name) != 0) {
527			/* nope */
528			if (fpw != NULL)
529				free(fpw);
530			if (write(tfd, p, q - p + 1) != q - p + 1)
531				goto err;
532			++q;
533			continue;
534		}
535		if (old_pw && !pw_equal(fpw, old_pw)) {
536			warnx("entry inconsistent");
537			free(fpw);
538			errno = EINVAL; /* hack */
539			goto err;
540		}
541		free(fpw);
542
543		/* it is, replace or remove it */
544		if (line != NULL) {
545			len = strlen(line);
546			if (write(tfd, line, len) != (int)len)
547				goto err;
548		} else {
549			/* when removed, avoid the \n */
550			q++;
551		}
552		/* we're done, just copy the rest over */
553		for (;;) {
554			if (write(tfd, q, end - q) != end - q)
555				goto err;
556			q = buf;
557			readlen = read(ffd, buf, size);
558			if (readlen == 0)
559				break;
560			else
561				len = (size_t)readlen;
562			if (readlen == -1)
563				goto err;
564			end = buf + len;
565		}
566		goto done;
567	}
568
569	/* if we got here, we didn't find the old entry */
570	if (line == NULL) {
571		errno = ENOENT;
572		goto err;
573	}
574	len = strlen(line);
575	if ((size_t)write(tfd, line, len) != len ||
576	    write(tfd, "\n", 1) != 1)
577		goto err;
578 done:
579	free(line);
580	free(buf);
581	return (0);
582 err:
583	free(line);
584	free(buf);
585	return (-1);
586}
587
588/*
589 * Return the current value of tempname.
590 */
591const char *
592pw_tempname(void)
593{
594
595	return (tempname);
596}
597
598/*
599 * Duplicate a struct passwd.
600 */
601struct passwd *
602pw_dup(const struct passwd *pw)
603{
604	char *dst;
605	struct passwd *npw;
606	ssize_t len;
607
608	len = sizeof(*npw);
609	if (pw->pw_name != NULL)
610		len += strlen(pw->pw_name) + 1;
611	if (pw->pw_passwd != NULL)
612		len += strlen(pw->pw_passwd) + 1;
613	if (pw->pw_class != NULL)
614		len += strlen(pw->pw_class) + 1;
615	if (pw->pw_gecos != NULL)
616		len += strlen(pw->pw_gecos) + 1;
617	if (pw->pw_dir != NULL)
618		len += strlen(pw->pw_dir) + 1;
619	if (pw->pw_shell != NULL)
620		len += strlen(pw->pw_shell) + 1;
621	if ((npw = malloc((size_t)len)) == NULL)
622		return (NULL);
623	memcpy(npw, pw, sizeof(*npw));
624	dst = (char *)npw + sizeof(*npw);
625	if (pw->pw_name != NULL) {
626		npw->pw_name = dst;
627		dst = stpcpy(npw->pw_name, pw->pw_name) + 1;
628	}
629	if (pw->pw_passwd != NULL) {
630		npw->pw_passwd = dst;
631		dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1;
632	}
633	if (pw->pw_class != NULL) {
634		npw->pw_class = dst;
635		dst = stpcpy(npw->pw_class, pw->pw_class) + 1;
636	}
637	if (pw->pw_gecos != NULL) {
638		npw->pw_gecos = dst;
639		dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1;
640	}
641	if (pw->pw_dir != NULL) {
642		npw->pw_dir = dst;
643		dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1;
644	}
645	if (pw->pw_shell != NULL) {
646		npw->pw_shell = dst;
647		dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1;
648	}
649	return (npw);
650}
651
652#include "pw_scan.h"
653
654/*
655 * Wrapper around some internal libc functions.
656 */
657
658void
659pw_initpwd(struct passwd *pw)
660{
661
662	__pw_initpwd(pw);
663}
664
665struct passwd *
666pw_scan(const char *line, int flags)
667{
668	struct passwd pw, *ret;
669	char *bp;
670
671	if ((bp = strdup(line)) == NULL)
672		return (NULL);
673	__pw_initpwd(&pw);
674	if (!__pw_scan(bp, &pw, flags)) {
675		free(bp);
676		return (NULL);
677	}
678	ret = pw_dup(&pw);
679	free(bp);
680	return (ret);
681}
682