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#include <sys/cdefs.h>
40__FBSDID("$FreeBSD$");
41__SCCSID("@(#)pw_util.c	8.3 (Berkeley) 4/2/94");
42
43/*
44 * This file is used by all the "password" programs; vipw(8), chpass(1),
45 * and passwd(1).
46 */
47
48#include <sys/param.h>
49#include <sys/errno.h>
50#include <sys/time.h>
51#include <sys/resource.h>
52#include <sys/stat.h>
53#include <sys/wait.h>
54
55#include <ctype.h>
56#include <err.h>
57#include <fcntl.h>
58#include <inttypes.h>
59#include <paths.h>
60#include <pwd.h>
61#include <signal.h>
62#include <stdio.h>
63#include <stdlib.h>
64#include <string.h>
65#include <unistd.h>
66
67#include "libutil.h"
68
69static pid_t editpid = -1;
70static int lockfd = -1;
71static char masterpasswd[PATH_MAX];
72static char passwd_dir[PATH_MAX];
73static char tempname[PATH_MAX];
74static int initialized;
75
76#if 0
77void
78pw_cont(int sig)
79{
80
81	if (editpid != -1)
82		kill(editpid, sig);
83}
84#endif
85
86/*
87 * Initialize statics and set limits, signals & umask to try to avoid
88 * interruptions, crashes etc. that might expose passord data.
89 */
90int
91pw_init(const char *dir, const char *master)
92{
93#if 0
94	struct rlimit rlim;
95#endif
96
97	if (dir == NULL) {
98		strcpy(passwd_dir, _PATH_ETC);
99	} else {
100		if (strlen(dir) >= sizeof(passwd_dir)) {
101			errno = ENAMETOOLONG;
102			return (-1);
103		}
104		strcpy(passwd_dir, dir);
105	}
106
107	if (master == NULL) {
108		if (dir == NULL) {
109			strcpy(masterpasswd, _PATH_MASTERPASSWD);
110		} else if (snprintf(masterpasswd, sizeof(masterpasswd), "%s/%s",
111		    passwd_dir, _MASTERPASSWD) > (int)sizeof(masterpasswd)) {
112			errno = ENAMETOOLONG;
113			return (-1);
114		}
115	} else {
116		if (strlen(master) >= sizeof(masterpasswd)) {
117			errno = ENAMETOOLONG;
118			return (-1);
119		}
120		strcpy(masterpasswd, master);
121	}
122
123	/*
124	 * The code that follows is extremely disruptive to the calling
125	 * process, and is therefore disabled until someone can conceive
126	 * of a realistic scenario where it would fend off a compromise.
127	 * Race conditions concerning the temporary files can be guarded
128	 * against in other ways than masking signals (by checking stat(2)
129	 * results after creation).
130	 */
131#if 0
132	/* Unlimited resource limits. */
133	rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
134	(void)setrlimit(RLIMIT_CPU, &rlim);
135	(void)setrlimit(RLIMIT_FSIZE, &rlim);
136	(void)setrlimit(RLIMIT_STACK, &rlim);
137	(void)setrlimit(RLIMIT_DATA, &rlim);
138	(void)setrlimit(RLIMIT_RSS, &rlim);
139
140	/* Don't drop core (not really necessary, but GP's). */
141	rlim.rlim_cur = rlim.rlim_max = 0;
142	(void)setrlimit(RLIMIT_CORE, &rlim);
143
144	/* Turn off signals. */
145	(void)signal(SIGALRM, SIG_IGN);
146	(void)signal(SIGHUP, SIG_IGN);
147	(void)signal(SIGINT, SIG_IGN);
148	(void)signal(SIGPIPE, SIG_IGN);
149	(void)signal(SIGQUIT, SIG_IGN);
150	(void)signal(SIGTERM, SIG_IGN);
151	(void)signal(SIGCONT, pw_cont);
152
153	/* Create with exact permissions. */
154	(void)umask(0);
155#endif
156	initialized = 1;
157	return (0);
158}
159
160/*
161 * Lock the master password file.
162 */
163int
164pw_lock(void)
165{
166
167	if (*masterpasswd == '\0')
168		return (-1);
169
170	/*
171	 * If the master password file doesn't exist, the system is hosed.
172	 * Might as well try to build one.  Set the close-on-exec bit so
173	 * that users can't get at the encrypted passwords while editing.
174	 * Open should allow flock'ing the file; see 4.4BSD.	XXX
175	 */
176	for (;;) {
177		struct stat st;
178
179		lockfd = flopen(masterpasswd, O_RDONLY|O_NONBLOCK|O_CLOEXEC, 0);
180		if (lockfd == -1) {
181			if (errno == EWOULDBLOCK) {
182				errx(1, "the password db file is busy");
183			} else {
184				err(1, "could not lock the passwd file");
185			}
186		}
187
188		/*
189		 * If the password file was replaced while we were trying to
190		 * get the lock, our hardlink count will be 0 and we have to
191		 * close and retry.
192		 */
193		if (fstat(lockfd, &st) == -1)
194			err(1, "fstat() failed");
195		if (st.st_nlink != 0)
196			break;
197		close(lockfd);
198		lockfd = -1;
199	}
200	return (lockfd);
201}
202
203/*
204 * Create and open a presumably safe temp file for editing the password
205 * data, and copy the master password file into it.
206 */
207int
208pw_tmp(int mfd)
209{
210	char buf[8192];
211	ssize_t nr;
212	const char *p;
213	int tfd;
214
215	if (*masterpasswd == '\0')
216		return (-1);
217	if ((p = strrchr(masterpasswd, '/')))
218		++p;
219	else
220		p = masterpasswd;
221	if (snprintf(tempname, sizeof(tempname), "%.*spw.XXXXXX",
222		(int)(p - masterpasswd), masterpasswd) >= (int)sizeof(tempname)) {
223		errno = ENAMETOOLONG;
224		return (-1);
225	}
226	if ((tfd = mkostemp(tempname, 0)) == -1)
227		return (-1);
228	if (mfd != -1) {
229		while ((nr = read(mfd, buf, sizeof(buf))) > 0)
230			if (write(tfd, buf, (size_t)nr) != nr)
231				break;
232		if (nr != 0) {
233			unlink(tempname);
234			*tempname = '\0';
235			close(tfd);
236			return (-1);
237		}
238	}
239	return (tfd);
240}
241
242/*
243 * Regenerate the password database.
244 */
245int
246pw_mkdb(const char *user)
247{
248	int pstat;
249	pid_t pid;
250
251	(void)fflush(stderr);
252	switch ((pid = fork())) {
253	case -1:
254		return (-1);
255	case 0:
256		/* child */
257		if (user == NULL)
258			execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
259			    "-d", passwd_dir, tempname, (char *)NULL);
260		else
261			execl(_PATH_PWD_MKDB, "pwd_mkdb", "-p",
262			    "-d", passwd_dir, "-u", user, tempname,
263			    (char *)NULL);
264		_exit(1);
265		/* NOTREACHED */
266	default:
267		/* parent */
268		break;
269	}
270	if (waitpid(pid, &pstat, 0) == -1)
271		return (-1);
272	if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
273		return (0);
274	errno = 0;
275	return (-1);
276}
277
278/*
279 * Edit the temp file.  Return -1 on error, >0 if the file was modified, 0
280 * if it was not.
281 */
282int
283pw_edit(int notsetuid)
284{
285	struct sigaction sa, sa_int, sa_quit;
286	sigset_t oldsigset, nsigset;
287	struct stat st1, st2;
288	const char *editor;
289	int pstat;
290
291	if ((editor = getenv("EDITOR")) == NULL)
292		editor = _PATH_VI;
293	if (stat(tempname, &st1) == -1)
294		return (-1);
295	sa.sa_handler = SIG_IGN;
296	sigemptyset(&sa.sa_mask);
297	sa.sa_flags = 0;
298	sigaction(SIGINT, &sa, &sa_int);
299	sigaction(SIGQUIT, &sa, &sa_quit);
300	sigemptyset(&nsigset);
301	sigaddset(&nsigset, SIGCHLD);
302	sigprocmask(SIG_BLOCK, &nsigset, &oldsigset);
303	switch ((editpid = fork())) {
304	case -1:
305		return (-1);
306	case 0:
307		sigaction(SIGINT, &sa_int, NULL);
308		sigaction(SIGQUIT, &sa_quit, NULL);
309		sigprocmask(SIG_SETMASK, &oldsigset, NULL);
310		if (notsetuid) {
311			if (setgid(getgid()) == -1)
312				err(1, "setgid");
313			if (setuid(getuid()) == -1)
314				err(1, "setuid");
315		}
316		execlp(editor, editor, tempname, (char *)NULL);
317		err(1, "%s", editor);
318	default:
319		/* parent */
320		break;
321	}
322	for (;;) {
323		if (waitpid(editpid, &pstat, WUNTRACED) == -1) {
324			if (errno == EINTR)
325				continue;
326			unlink(tempname);
327			editpid = -1;
328			break;
329		} else if (WIFSTOPPED(pstat)) {
330			raise(WSTOPSIG(pstat));
331		} else if (WIFEXITED(pstat)) {
332			if (WEXITSTATUS(pstat) != 0)
333				errx(1, "\"%s\" exited with status %d", editor, WEXITSTATUS(pstat));
334			editpid = -1;
335			break;
336		} else {
337			unlink(tempname);
338			editpid = -1;
339			break;
340		}
341	}
342	sigaction(SIGINT, &sa_int, NULL);
343	sigaction(SIGQUIT, &sa_quit, NULL);
344	sigprocmask(SIG_SETMASK, &oldsigset, NULL);
345	if (stat(tempname, &st2) == -1)
346		return (-1);
347	return (st1.st_mtim.tv_sec != st2.st_mtim.tv_sec ||
348	    st1.st_mtim.tv_nsec != st2.st_mtim.tv_nsec);
349}
350
351/*
352 * Clean up.  Preserve errno for the caller's convenience.
353 */
354void
355pw_fini(void)
356{
357	int serrno, status;
358
359	if (!initialized)
360		return;
361	initialized = 0;
362	serrno = errno;
363	if (editpid != -1) {
364		kill(editpid, SIGTERM);
365		kill(editpid, SIGCONT);
366		waitpid(editpid, &status, 0);
367		editpid = -1;
368	}
369	if (*tempname != '\0') {
370		unlink(tempname);
371		*tempname = '\0';
372	}
373	if (lockfd != -1)
374		close(lockfd);
375	errno = serrno;
376}
377
378/*
379 * Compares two struct pwds.
380 */
381int
382pw_equal(const struct passwd *pw1, const struct passwd *pw2)
383{
384	return (strcmp(pw1->pw_name, pw2->pw_name) == 0 &&
385	    pw1->pw_uid == pw2->pw_uid &&
386	    pw1->pw_gid == pw2->pw_gid &&
387	    strcmp(pw1->pw_class, pw2->pw_class) == 0 &&
388	    pw1->pw_change == pw2->pw_change &&
389	    pw1->pw_expire == pw2->pw_expire &&
390	    strcmp(pw1->pw_gecos, pw2->pw_gecos) == 0 &&
391	    strcmp(pw1->pw_dir, pw2->pw_dir) == 0 &&
392	    strcmp(pw1->pw_shell, pw2->pw_shell) == 0);
393}
394
395/*
396 * Make a passwd line out of a struct passwd.
397 */
398char *
399pw_make(const struct passwd *pw)
400{
401	char *line;
402
403	asprintf(&line, "%s:%s:%ju:%ju:%s:%ju:%ju:%s:%s:%s", pw->pw_name,
404	    pw->pw_passwd, (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
405	    pw->pw_class, (uintmax_t)pw->pw_change, (uintmax_t)pw->pw_expire,
406	    pw->pw_gecos, pw->pw_dir, pw->pw_shell);
407	return (line);
408}
409
410/*
411 * Make a passwd line (in v7 format) out of a struct passwd
412 */
413char *
414pw_make_v7(const struct passwd *pw)
415{
416	char *line;
417
418	asprintf(&line, "%s:*:%ju:%ju:%s:%s:%s", pw->pw_name,
419	    (uintmax_t)pw->pw_uid, (uintmax_t)pw->pw_gid,
420	    pw->pw_gecos, pw->pw_dir, pw->pw_shell);
421	return (line);
422}
423
424/*
425 * Copy password file from one descriptor to another, replacing, deleting
426 * or adding a single record on the way.
427 */
428int
429pw_copy(int ffd, int tfd, const struct passwd *pw, struct passwd *old_pw)
430{
431	char *buf, *end, *line, *p, *q, *r, *tmp;
432	struct passwd *fpw;
433	const struct passwd *spw;
434	size_t len, size;
435	int eof, readlen;
436	char t;
437
438	if (old_pw == NULL && pw == NULL)
439			return (-1);
440
441	spw = old_pw;
442	/* deleting a user */
443	if (pw == NULL) {
444		line = NULL;
445	} else {
446		if ((line = pw_make(pw)) == NULL)
447			return (-1);
448	}
449
450	/* adding a user */
451	if (spw == NULL)
452		spw = pw;
453
454	/* initialize the buffer */
455	if ((buf = malloc(size = 1024)) == NULL)
456		goto err;
457
458	eof = 0;
459	len = 0;
460	p = q = end = buf;
461	for (;;) {
462		/* find the end of the current line */
463		for (p = q; q < end && *q != '\0'; ++q)
464			if (*q == '\n')
465				break;
466
467		/* if we don't have a complete line, fill up the buffer */
468		if (q >= end) {
469			if (eof)
470				break;
471			while ((size_t)(q - p) >= size) {
472				if ((tmp = reallocarray(buf, 2, size)) == NULL) {
473					warnx("passwd line too long");
474					goto err;
475				}
476				p = tmp + (p - buf);
477				q = tmp + (q - buf);
478				end = tmp + (end - buf);
479				buf = tmp;
480				size = size * 2;
481			}
482			if (p < end) {
483				q = memmove(buf, p, end - p);
484				end -= p - buf;
485			} else {
486				p = q = end = buf;
487			}
488			readlen = read(ffd, end, size - (end - buf));
489			if (readlen == -1)
490				goto err;
491			else
492				len = (size_t)readlen;
493			if (len == 0 && p == buf)
494				break;
495			end += len;
496			len = end - buf;
497			if (len < size) {
498				eof = 1;
499				if (len > 0 && buf[len - 1] != '\n')
500					++len, *end++ = '\n';
501			}
502			continue;
503		}
504
505		/* is it a blank line or a comment? */
506		for (r = p; r < q && isspace(*r); ++r)
507			/* nothing */ ;
508		if (r == q || *r == '#') {
509			/* yep */
510			if (write(tfd, p, q - p + 1) != q - p + 1)
511				goto err;
512			++q;
513			continue;
514		}
515
516		/* is it the one we're looking for? */
517
518		t = *q;
519		*q = '\0';
520
521		fpw = pw_scan(r, PWSCAN_MASTER);
522
523		/*
524		 * fpw is either the struct passwd for the current line,
525		 * or NULL if the line is malformed.
526		 */
527
528		*q = t;
529		if (fpw == NULL || strcmp(fpw->pw_name, spw->pw_name) != 0) {
530			/* nope */
531			if (fpw != NULL)
532				free(fpw);
533			if (write(tfd, p, q - p + 1) != q - p + 1)
534				goto err;
535			++q;
536			continue;
537		}
538		if (old_pw && !pw_equal(fpw, old_pw)) {
539			warnx("entry inconsistent");
540			free(fpw);
541			errno = EINVAL; /* hack */
542			goto err;
543		}
544		free(fpw);
545
546		/* it is, replace or remove it */
547		if (line != NULL) {
548			len = strlen(line);
549			if (write(tfd, line, len) != (int)len)
550				goto err;
551		} else {
552			/* when removed, avoid the \n */
553			q++;
554		}
555		/* we're done, just copy the rest over */
556		for (;;) {
557			if (write(tfd, q, end - q) != end - q)
558				goto err;
559			q = buf;
560			readlen = read(ffd, buf, size);
561			if (readlen == 0)
562				break;
563			else
564				len = (size_t)readlen;
565			if (readlen == -1)
566				goto err;
567			end = buf + len;
568		}
569		goto done;
570	}
571
572	/* if we got here, we didn't find the old entry */
573	if (line == NULL) {
574		errno = ENOENT;
575		goto err;
576	}
577	len = strlen(line);
578	if ((size_t)write(tfd, line, len) != len ||
579	    write(tfd, "\n", 1) != 1)
580		goto err;
581 done:
582	free(line);
583	free(buf);
584	return (0);
585 err:
586	free(line);
587	free(buf);
588	return (-1);
589}
590
591/*
592 * Return the current value of tempname.
593 */
594const char *
595pw_tempname(void)
596{
597
598	return (tempname);
599}
600
601/*
602 * Duplicate a struct passwd.
603 */
604struct passwd *
605pw_dup(const struct passwd *pw)
606{
607	char *dst;
608	struct passwd *npw;
609	ssize_t len;
610
611	len = sizeof(*npw);
612	if (pw->pw_name != NULL)
613		len += strlen(pw->pw_name) + 1;
614	if (pw->pw_passwd != NULL)
615		len += strlen(pw->pw_passwd) + 1;
616	if (pw->pw_class != NULL)
617		len += strlen(pw->pw_class) + 1;
618	if (pw->pw_gecos != NULL)
619		len += strlen(pw->pw_gecos) + 1;
620	if (pw->pw_dir != NULL)
621		len += strlen(pw->pw_dir) + 1;
622	if (pw->pw_shell != NULL)
623		len += strlen(pw->pw_shell) + 1;
624	if ((npw = malloc((size_t)len)) == NULL)
625		return (NULL);
626	memcpy(npw, pw, sizeof(*npw));
627	dst = (char *)npw + sizeof(*npw);
628	if (pw->pw_name != NULL) {
629		npw->pw_name = dst;
630		dst = stpcpy(npw->pw_name, pw->pw_name) + 1;
631	}
632	if (pw->pw_passwd != NULL) {
633		npw->pw_passwd = dst;
634		dst = stpcpy(npw->pw_passwd, pw->pw_passwd) + 1;
635	}
636	if (pw->pw_class != NULL) {
637		npw->pw_class = dst;
638		dst = stpcpy(npw->pw_class, pw->pw_class) + 1;
639	}
640	if (pw->pw_gecos != NULL) {
641		npw->pw_gecos = dst;
642		dst = stpcpy(npw->pw_gecos, pw->pw_gecos) + 1;
643	}
644	if (pw->pw_dir != NULL) {
645		npw->pw_dir = dst;
646		dst = stpcpy(npw->pw_dir, pw->pw_dir) + 1;
647	}
648	if (pw->pw_shell != NULL) {
649		npw->pw_shell = dst;
650		dst = stpcpy(npw->pw_shell, pw->pw_shell) + 1;
651	}
652	return (npw);
653}
654
655#include "pw_scan.h"
656
657/*
658 * Wrapper around some internal libc functions.
659 */
660
661void
662pw_initpwd(struct passwd *pw)
663{
664
665	__pw_initpwd(pw);
666}
667
668struct passwd *
669pw_scan(const char *line, int flags)
670{
671	struct passwd pw, *ret;
672	char *bp;
673
674	if ((bp = strdup(line)) == NULL)
675		return (NULL);
676	__pw_initpwd(&pw);
677	if (!__pw_scan(bp, &pw, flags)) {
678		free(bp);
679		return (NULL);
680	}
681	ret = pw_dup(&pw);
682	free(bp);
683	return (ret);
684}
685