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      1 /*	$NetBSD: passwd.c,v 1.53 2018/06/24 01:53:14 kamil Exp $	*/
      2 
      3 /*
      4  * Copyright (c) 1987, 1993, 1994, 1995
      5  *	The Regents of the University of California.  All rights reserved.
      6  *
      7  * Redistribution and use in source and binary forms, with or without
      8  * modification, are permitted provided that the following conditions
      9  * are met:
     10  * 1. Redistributions of source code must retain the above copyright
     11  *    notice, this list of conditions and the following disclaimer.
     12  * 2. Redistributions in binary form must reproduce the above copyright
     13  *    notice, this list of conditions and the following disclaimer in the
     14  *    documentation and/or other materials provided with the distribution.
     15  * 3. Neither the name of the University nor the names of its contributors
     16  *    may be used to endorse or promote products derived from this software
     17  *    without specific prior written permission.
     18  *
     19  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
     20  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     21  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     22  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
     23  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     24  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     25  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     26  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     27  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     28  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     29  * SUCH DAMAGE.
     30  */
     31 
     32 #include <sys/cdefs.h>
     33 #if defined(LIBC_SCCS) && !defined(lint)
     34 __RCSID("$NetBSD: passwd.c,v 1.53 2018/06/24 01:53:14 kamil Exp $");
     35 #endif /* LIBC_SCCS and not lint */
     36 
     37 #include <sys/types.h>
     38 #include <sys/param.h>
     39 #include <sys/stat.h>
     40 #include <sys/time.h>
     41 #include <sys/resource.h>
     42 #include <sys/wait.h>
     43 
     44 #include <assert.h>
     45 #include <ctype.h>
     46 #include <err.h>
     47 #include <errno.h>
     48 #include <fcntl.h>
     49 #include <limits.h>
     50 #include <paths.h>
     51 #include <pwd.h>
     52 #include <grp.h>
     53 #include <signal.h>
     54 #include <stdio.h>
     55 #include <stdlib.h>
     56 #include <string.h>
     57 #include <unistd.h>
     58 #include <util.h>
     59 
     60 static const char      *pw_filename(const char *filename);
     61 static void		pw_cont(int sig);
     62 static const char *	pw_equal(char *buf, struct passwd *old_pw);
     63 static const char      *pw_default(const char *option);
     64 static int		read_line(FILE *fp, char *line, int max);
     65 static void		trim_whitespace(char *line);
     66 
     67 static	char	pw_prefix[MAXPATHLEN];
     68 
     69 const char *
     70 pw_getprefix(void)
     71 {
     72 
     73 	return(pw_prefix);
     74 }
     75 
     76 int
     77 pw_setprefix(const char *new_prefix)
     78 {
     79 	size_t length;
     80 
     81 	_DIAGASSERT(new_prefix != NULL);
     82 
     83 	length = strlen(new_prefix);
     84 	if (length < sizeof(pw_prefix)) {
     85 		(void)strcpy(pw_prefix, new_prefix);
     86 		while (length > 0 && pw_prefix[length - 1] == '/')
     87 			pw_prefix[--length] = '\0';
     88 		return(0);
     89 	}
     90 	errno = ENAMETOOLONG;
     91 	return(-1);
     92 }
     93 
     94 static const char *
     95 pw_filename(const char *filename)
     96 {
     97 	static char newfilename[MAXPATHLEN];
     98 
     99 	_DIAGASSERT(filename != NULL);
    100 
    101 	if (pw_prefix[0] == '\0')
    102 		return filename;
    103 
    104 	if (strlen(pw_prefix) + strlen(filename) < sizeof(newfilename))
    105 		return strcat(strcpy(newfilename, pw_prefix), filename);
    106 
    107 	errno = ENAMETOOLONG;
    108 	return(NULL);
    109 }
    110 
    111 int
    112 pw_lock(int retries)
    113 {
    114 	const char *filename;
    115 	int i, fd;
    116 	mode_t old_mode;
    117 	int oerrno;
    118 
    119 	/* Acquire the lock file. */
    120 	filename = pw_filename(_PATH_MASTERPASSWD_LOCK);
    121 	if (filename == NULL)
    122 		return(-1);
    123 	old_mode = umask(0);
    124 	fd = open(filename, O_WRONLY|O_CREAT|O_EXCL, 0600);
    125 	for (i = 0; i < retries && fd < 0 && errno == EEXIST; i++) {
    126 		sleep(1);
    127 		fd = open(filename, O_WRONLY|O_CREAT|O_EXCL,
    128 			  0600);
    129 	}
    130 	oerrno = errno;
    131 	(void)umask(old_mode);
    132 	errno = oerrno;
    133 	return(fd);
    134 }
    135 
    136 int
    137 pw_mkdb(const char *username, int secureonly)
    138 {
    139 	const char *args[9];
    140 	int pstat, i;
    141 	pid_t pid;
    142 
    143 	pid = vfork();
    144 	if (pid == -1)
    145 		return -1;
    146 
    147 	if (pid == 0) {
    148 		args[0] = "pwd_mkdb";
    149 		args[1] = "-d";
    150 		args[2] = pw_prefix;
    151 		args[3] = "-pl";
    152 		i = 4;
    153 
    154 		if (secureonly)
    155 			args[i++] = "-s";
    156 		if (username != NULL) {
    157 			args[i++] = "-u";
    158 			args[i++] = username;
    159 		}
    160 
    161 		args[i++] = pw_filename(_PATH_MASTERPASSWD_LOCK);
    162 		args[i] = NULL;
    163 		execv(_PATH_PWD_MKDB, (char * const *)__UNCONST(args));
    164 		_exit(1);
    165 	}
    166 	pid = waitpid(pid, &pstat, 0);
    167 	if (pid == -1) {
    168 		warn("error waiting for pid %lu", (unsigned long)pid);
    169 		return -1;
    170 	}
    171 	if (WIFEXITED(pstat)) {
    172 		if (WEXITSTATUS(pstat) != 0) {
    173 			warnx("pwd_mkdb exited with status %d",
    174 			    WEXITSTATUS(pstat));
    175 			return -1;
    176 		}
    177 	} else if (WIFSIGNALED(pstat)) {
    178 		warnx("pwd_mkdb exited with signal %d", WTERMSIG(pstat));
    179 		return -1;
    180 	}
    181 	return 0;
    182 }
    183 
    184 int
    185 pw_abort(void)
    186 {
    187 	const char *filename;
    188 
    189 	filename = pw_filename(_PATH_MASTERPASSWD_LOCK);
    190 	return((filename == NULL) ? -1 : unlink(filename));
    191 }
    192 
    193 /* Everything below this point is intended for the convenience of programs
    194  * which allow a user to interactively edit the passwd file.  Errors in the
    195  * routines below will cause the process to abort. */
    196 
    197 static pid_t editpid = -1;
    198 
    199 static void
    200 pw_cont(int sig)
    201 {
    202 
    203 	if (editpid != -1)
    204 		kill(editpid, sig);
    205 }
    206 
    207 void
    208 pw_init(void)
    209 {
    210 	struct rlimit rlim;
    211 
    212 	/* Unlimited resource limits. */
    213 	rlim.rlim_cur = rlim.rlim_max = RLIM_INFINITY;
    214 	(void)setrlimit(RLIMIT_CPU, &rlim);
    215 	(void)setrlimit(RLIMIT_FSIZE, &rlim);
    216 	(void)setrlimit(RLIMIT_STACK, &rlim);
    217 	(void)setrlimit(RLIMIT_DATA, &rlim);
    218 	(void)setrlimit(RLIMIT_RSS, &rlim);
    219 
    220 	/* Don't drop core (not really necessary, but GP's). */
    221 	rlim.rlim_cur = rlim.rlim_max = 0;
    222 	(void)setrlimit(RLIMIT_CORE, &rlim);
    223 
    224 	/* Turn off signals. */
    225 	(void)signal(SIGALRM, SIG_IGN);
    226 	(void)signal(SIGHUP, SIG_IGN);
    227 	(void)signal(SIGINT, SIG_IGN);
    228 	(void)signal(SIGPIPE, SIG_IGN);
    229 	(void)signal(SIGQUIT, SIG_IGN);
    230 	(void)signal(SIGTERM, SIG_IGN);
    231 	(void)signal(SIGCONT, pw_cont);
    232 }
    233 
    234 void
    235 pw_edit(int notsetuid, const char *filename)
    236 {
    237 	int pstat;
    238 	char *p;
    239 	const char * volatile editor;
    240 	const char *argp[] = { "sh", "-c", NULL, NULL };
    241 
    242 	if (filename == NULL)
    243 		filename = _PATH_MASTERPASSWD_LOCK;
    244 
    245 	filename = pw_filename(filename);
    246 	if (filename == NULL)
    247 		return;
    248 
    249 	if ((editor = getenv("EDITOR")) == NULL)
    250 		editor = _PATH_VI;
    251 
    252 	p = malloc(strlen(editor) + 1 + strlen(filename) + 1);
    253 	if (p == NULL)
    254 		return;
    255 
    256 	sprintf(p, "%s %s", editor, filename);
    257 	argp[2] = p;
    258 
    259 	switch(editpid = vfork()) {
    260 	case -1:
    261 		free(p);
    262 		return;
    263 	case 0:
    264 		if (notsetuid) {
    265 			setgid(getgid());
    266 			setuid(getuid());
    267 		}
    268 		execvp(_PATH_BSHELL, (char *const *)__UNCONST(argp));
    269 		_exit(1);
    270 	}
    271 
    272 	free(p);
    273 
    274 	for (;;) {
    275 		editpid = waitpid(editpid, (int *)&pstat, WUNTRACED);
    276 		if (editpid == -1)
    277 			pw_error(editor, 1, 1);
    278 		else if (WIFSTOPPED(pstat))
    279 			raise(WSTOPSIG(pstat));
    280 		else if (WIFEXITED(pstat) && WEXITSTATUS(pstat) == 0)
    281 			break;
    282 		else
    283 			pw_error(editor, 1, 1);
    284 	}
    285 	editpid = -1;
    286 }
    287 
    288 void
    289 pw_prompt(void)
    290 {
    291 	int c;
    292 
    293 	(void)printf("re-edit the password file? [y]: ");
    294 	(void)fflush(stdout);
    295 	c = getchar();
    296 	if (c != EOF && c != '\n')
    297 		while (getchar() != '\n');
    298 	if (c == 'n')
    299 		pw_error(NULL, 0, 0);
    300 }
    301 
    302 /* for use in pw_copy(). Compare a pw entry to a pw struct. */
    303 /* returns a character string labelling the miscompared field or 0 */
    304 static const char *
    305 pw_equal(char *buf, struct passwd *pw)
    306 {
    307 	struct passwd buf_pw;
    308 	size_t len;
    309 
    310 	_DIAGASSERT(buf != NULL);
    311 	_DIAGASSERT(pw != NULL);
    312 
    313 	len = strlen (buf);
    314 	if (buf[len-1] == '\n')
    315 		buf[len-1] = '\0';
    316 	if (!pw_scan(buf, &buf_pw, NULL))
    317 		return "corrupt line";
    318 	if (strcmp(pw->pw_name, buf_pw.pw_name) != 0)
    319 		return "name";
    320 	if (pw->pw_uid != buf_pw.pw_uid)
    321 		return "uid";
    322 	if (pw->pw_gid != buf_pw.pw_gid)
    323 		return "gid";
    324 	if (strcmp( pw->pw_class, buf_pw.pw_class) != 0)
    325 		return "class";
    326 	if (pw->pw_change != buf_pw.pw_change)
    327 		return "change";
    328 	if (pw->pw_expire != buf_pw.pw_expire)
    329 		return "expire";
    330 	if (strcmp( pw->pw_gecos, buf_pw.pw_gecos) != 0)
    331 		return "gecos";
    332 	if (strcmp( pw->pw_dir, buf_pw.pw_dir) != 0)
    333 		return "dir";
    334 	if (strcmp( pw->pw_shell, buf_pw.pw_shell) != 0)
    335 		return "shell";
    336 	return (char *)0;
    337 }
    338 
    339 void
    340 pw_copy(int ffd, int tfd, struct passwd *pw, struct passwd *old_pw)
    341 {
    342 	char errbuf[200];
    343 	int rv;
    344 
    345 	rv = pw_copyx(ffd, tfd, pw, old_pw, errbuf, sizeof(errbuf));
    346 	if (rv == 0) {
    347 		warnx("%s", errbuf);
    348 		pw_error(NULL, 0, 1);
    349 	}
    350 }
    351 
    352 static void
    353 pw_print(FILE *to, const struct passwd *pw)
    354 {
    355 	(void)fprintf(to, "%s:%s:%d:%d:%s:%lld:%lld:%s:%s:%s\n",
    356 	    pw->pw_name, pw->pw_passwd, pw->pw_uid, pw->pw_gid,
    357 	    pw->pw_class, (long long)pw->pw_change,
    358 	    (long long)pw->pw_expire,
    359 	    pw->pw_gecos, pw->pw_dir, pw->pw_shell);
    360 }
    361 
    362 int
    363 pw_copyx(int ffd, int tfd, struct passwd *pw, struct passwd *old_pw,
    364     char *errbuf, size_t errbufsz)
    365 {
    366 	const char *filename;
    367 	char mpwd[MAXPATHLEN], mpwdl[MAXPATHLEN], *p, buf[8192];
    368 	FILE *from, *to;
    369 	int done;
    370 
    371 	_DIAGASSERT(pw != NULL);
    372 	_DIAGASSERT(errbuf != NULL);
    373 	/* old_pw may be NULL */
    374 
    375 	if ((filename = pw_filename(_PATH_MASTERPASSWD)) == NULL) {
    376 		snprintf(errbuf, errbufsz, "%s: %s", pw_prefix,
    377 		    strerror(errno));
    378 		return (0);
    379 	}
    380 	(void)strcpy(mpwd, filename);
    381 	if ((filename = pw_filename(_PATH_MASTERPASSWD_LOCK)) == NULL) {
    382 		snprintf(errbuf, errbufsz, "%s: %s", pw_prefix,
    383 		    strerror(errno));
    384 		return (0);
    385 	}
    386 	(void)strcpy(mpwdl, filename);
    387 
    388 	if (!(from = fdopen(ffd, "r"))) {
    389 		snprintf(errbuf, errbufsz, "%s: %s", mpwd, strerror(errno));
    390 		return (0);
    391 	}
    392 	if (!(to = fdopen(tfd, "w"))) {
    393 		snprintf(errbuf, errbufsz, "%s: %s", mpwdl, strerror(errno));
    394 		(void)fclose(from);
    395 		return (0);
    396 	}
    397 
    398 	for (done = 0; fgets(buf, (int)sizeof(buf), from);) {
    399 		const char *neq;
    400 		if (!strchr(buf, '\n')) {
    401 			snprintf(errbuf, errbufsz, "%s: line too long", mpwd);
    402 			(void)fclose(from);
    403 			(void)fclose(to);
    404 			return (0);
    405 		}
    406 		if (done) {
    407 			(void)fprintf(to, "%s", buf);
    408 			if (ferror(to)) {
    409 				snprintf(errbuf, errbufsz, "%s",
    410 				    strerror(errno));
    411 				(void)fclose(from);
    412 				(void)fclose(to);
    413 				return (0);
    414 			}
    415 			continue;
    416 		}
    417 		if (!(p = strchr(buf, ':'))) {
    418 			snprintf(errbuf, errbufsz, "%s: corrupted entry", mpwd);
    419 			(void)fclose(from);
    420 			(void)fclose(to);
    421 			return (0);
    422 		}
    423 		*p = '\0';
    424 		if (strcmp(buf, pw->pw_name)) {
    425 			*p = ':';
    426 			(void)fprintf(to, "%s", buf);
    427 			if (ferror(to)) {
    428 				snprintf(errbuf, errbufsz, "%s",
    429 				    strerror(errno));
    430 				(void)fclose(from);
    431 				(void)fclose(to);
    432 				return (0);
    433 			}
    434 			continue;
    435 		}
    436 		*p = ':';
    437 		if (old_pw && (neq = pw_equal(buf, old_pw)) != NULL) {
    438 			if (strcmp(neq, "corrupt line") == 0)
    439 				(void)snprintf(errbuf, errbufsz,
    440 				    "%s: entry %s corrupted", mpwd,
    441 				    pw->pw_name);
    442 			else
    443 				(void)snprintf(errbuf, errbufsz,
    444 				    "%s: entry %s inconsistent %s",
    445 				    mpwd, pw->pw_name, neq);
    446 			(void)fclose(from);
    447 			(void)fclose(to);
    448 			return (0);
    449 		}
    450 		pw_print(to, pw);
    451 		done = 1;
    452 		if (ferror(to)) {
    453 			snprintf(errbuf, errbufsz, "%s", strerror(errno));
    454 			(void)fclose(from);
    455 			(void)fclose(to);
    456 			return (0);
    457 		}
    458 	}
    459 	/* Only append a new entry if real uid is root! */
    460 	if (!done) {
    461 		if (getuid() == 0) {
    462 			pw_print(to, pw);
    463 			done = 1;
    464 		} else {
    465 			snprintf(errbuf, errbufsz,
    466 			    "%s: changes not made, no such entry", mpwd);
    467 		}
    468 	}
    469 
    470 	if (ferror(to)) {
    471 		snprintf(errbuf, errbufsz, "%s", strerror(errno));
    472 		(void)fclose(from);
    473 		(void)fclose(to);
    474 		return (0);
    475 	}
    476 	(void)fclose(from);
    477 	(void)fclose(to);
    478 
    479 	return (done);
    480 }
    481 
    482 void
    483 pw_error(const char *name, int error, int eval)
    484 {
    485 
    486 	if (error) {
    487 		if (name)
    488 			warn("%s", name);
    489 		else
    490 			warn(NULL);
    491 	}
    492 
    493 	warnx("%s%s: unchanged", pw_prefix, _PATH_MASTERPASSWD);
    494 	pw_abort();
    495 	exit(eval);
    496 }
    497 
    498 /* Removes head and/or tail spaces. */
    499 static void
    500 trim_whitespace(char *line)
    501 {
    502 	char *p;
    503 
    504 	_DIAGASSERT(line != NULL);
    505 
    506 	/* Handle empty string */
    507 	if (*line == '\0')
    508 		return;
    509 
    510 	/* Remove leading spaces */
    511 	p = line;
    512 	while (isspace((unsigned char) *p))
    513 		p++;
    514 	memmove(line, p, strlen(p) + 1);
    515 
    516 	/* Handle empty string after removal of whitespace characters */
    517 	if (*line == '\0')
    518 		return;
    519 
    520 	/* Remove trailing spaces, line must not be empty string here */
    521 	p = line + strlen(line) - 1;
    522 	while (isspace((unsigned char) *p))
    523 		p--;
    524 	*(p + 1) = '\0';
    525 }
    526 
    527 
    528 /* Get one line, remove spaces from front and tail */
    529 static int
    530 read_line(FILE *fp, char *line, int max)
    531 {
    532 	char   *p;
    533 
    534 	_DIAGASSERT(fp != NULL);
    535 	_DIAGASSERT(line != NULL);
    536 
    537 	/* Read one line of config */
    538 	if (fgets(line, max, fp) == NULL)
    539 		return (0);
    540 
    541 	if ((p = strchr(line, '\n')) == NULL) {
    542 		warnx("line too long");
    543 		return (0);
    544 	}
    545 	*p = '\0';
    546 
    547 	/* Remove comments */
    548 	if ((p = strchr(line, '#')) != NULL)
    549 		*p = '\0';
    550 
    551 	trim_whitespace(line);
    552 	return (1);
    553 }
    554 
    555 static const char *
    556 pw_default(const char *option)
    557 {
    558 	static const char *options[][2] = {
    559 		{ "localcipher",	"old" },
    560 		{ "ypcipher",		"old" },
    561 	};
    562 	size_t i;
    563 
    564 	_DIAGASSERT(option != NULL);
    565 	for (i = 0; i < sizeof(options) / sizeof(options[0]); i++)
    566 		if (strcmp(options[i][0], option) == 0)
    567 			return (options[i][1]);
    568 
    569 	return (NULL);
    570 }
    571 
    572 /*
    573  * Retrieve password information from the /etc/passwd.conf file, at the
    574  * moment this is only for choosing the cipher to use.  It could easily be
    575  * used for other authentication methods as well.
    576  */
    577 void
    578 pw_getconf(char *data, size_t max, const char *key, const char *option)
    579 {
    580 	FILE *fp;
    581 	char line[LINE_MAX], *p, *p2;
    582 	static char result[LINE_MAX];
    583 	int got, found;
    584 	const char *cp;
    585 
    586 	_DIAGASSERT(data != NULL);
    587 	_DIAGASSERT(key != NULL);
    588 	_DIAGASSERT(option != NULL);
    589 
    590 	got = 0;
    591 	found = 0;
    592 	result[0] = '\0';
    593 
    594 	if ((fp = fopen(_PATH_PASSWD_CONF, "r")) == NULL) {
    595 		if ((cp = pw_default(option)) != NULL)
    596 			strlcpy(data, cp, max);
    597 		else
    598 			data[0] = '\0';
    599 		return;
    600 	}
    601 
    602 	while (!found && (got || read_line(fp, line, LINE_MAX))) {
    603 		got = 0;
    604 
    605 		if (strncmp(key, line, strlen(key)) != 0 ||
    606 		    line[strlen(key)] != ':')
    607 			continue;
    608 
    609 		/* Now we found our specified key */
    610 		while (read_line(fp, line, LINE_MAX)) {
    611 			/* Leaving key field */
    612 			if (line[0] != '\0' && strchr(line + 1, ':') != NULL) {
    613 				got = 1;
    614 				break;
    615 			}
    616 			p2 = line;
    617 			if ((p = strsep(&p2, "=")) == NULL || p2 == NULL)
    618 				continue;
    619 			trim_whitespace(p);
    620 
    621 			if (!strncmp(p, option, strlen(option))) {
    622 				trim_whitespace(p2);
    623 				strcpy(result, p2);
    624 				found = 1;
    625 				break;
    626 			}
    627 		}
    628 	}
    629 	fclose(fp);
    630 
    631 	if (!found)
    632 		errno = ENOENT;
    633 	if (!got)
    634 		errno = ENOTDIR;
    635 
    636 	/*
    637 	 * If we got no result and were looking for a default
    638 	 * value, try hard coded defaults.
    639 	 */
    640 
    641 	if (strlen(result) == 0 && strcmp(key, "default") == 0 &&
    642 	    (cp = pw_default(option)) != NULL)
    643 		strlcpy(data, cp, max);
    644 	else
    645 		strlcpy(data, result, max);
    646 }
    647 
    648 void
    649 pw_getpwconf(char *data, size_t max, const struct passwd *pwd,
    650     const char *option)
    651 {
    652 	char grpkey[LINE_MAX];
    653 	struct group grs, *grp;
    654 	char grbuf[1024];
    655 
    656 	pw_getconf(data, max, pwd->pw_name, option);
    657 
    658 	/* Try to find an entry for the group */
    659 	if (*data == '\0') {
    660 		(void)getgrgid_r(pwd->pw_gid, &grs, grbuf, sizeof(grbuf), &grp);
    661 		if (grp != NULL) {
    662 			(void)snprintf(grpkey, sizeof(grpkey), ":%s",
    663 			    grp->gr_name);
    664 			pw_getconf(data, max, grpkey, option);
    665 		}
    666 		if (*data == '\0')
    667 		        pw_getconf(data, max, "default", option);
    668 	}
    669 }
    670