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rcsid[] and sccsid[] and copyright[] are essentially unmaintained (and
unmaintainable).  these days, people use source.  these id's do not provide
any benefit, and do hurt the small install media
(the 33,000 line diff is essentially mechanical)
ok with the idea millert, ok dms

/*	$OpenBSD: local_passwd.c,v 1.40 2009/10/27 23:59:41 deraadt Exp $	*/

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <sys/types.h>
#include <sys/stat.h>
#include <sys/uio.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
#include <string.h>
#include <unistd.h>
#include <util.h>
#include <login_cap.h>

#define UNCHANGED_MSG	"Password unchanged.\n"

static uid_t uid;
extern int pwd_gensalt(char *, int, login_cap_t *, char);
extern int pwd_check(login_cap_t *, char *);
extern int pwd_gettries(login_cap_t *);

int local_passwd(char *, int);
char *getnewpasswd(struct passwd *, login_cap_t *, int);
void kbintr(int);

int
local_passwd(char *uname, int authenticated)
{
	struct passwd *pw, *opw;
	login_cap_t *lc;
	sigset_t fullset;
	time_t period;
	int i, pfd, tfd = -1;
	int pwflags = _PASSWORD_OMITV7;

	if (!(pw = getpwnam(uname))) {
#ifdef YP
		extern int use_yp;
		if (!use_yp)
#endif
		warnx("unknown user %s.", uname);
		return(1);
	}
	if ((opw = pw_dup(pw)) == NULL) {
		warn(NULL);
		return(1);
	}
	if ((lc = login_getclass(pw->pw_class)) == NULL) {
		warnx("unable to get login class for user %s.", uname);
		free(opw);
		return(1);
	}

	uid = authenticated ? pw->pw_uid : getuid();
	if (uid && uid != pw->pw_uid) {
		warnx("login/uid mismatch, username argument required.");
		free(opw);
		return(1);
	}

	/* Get the new password. */
	pw->pw_passwd = getnewpasswd(pw, lc, authenticated);

	/* Reset password change time based on login.conf. */
	period = (time_t)login_getcaptime(lc, "passwordtime",
	    (quad_t)0, (quad_t)0);
	if (period > 0) {
		pw->pw_change = time(NULL) + period;
	} else {
		/*
		 * If the pw change time is the same we only need
		 * to update the spwd.db file.
		 */
		if (pw->pw_change != 0)
			pw->pw_change = 0;
		else
			pwflags = _PASSWORD_SECUREONLY;
	}

	/* Drop user's real uid and block all signals to avoid a DoS. */
	setuid(0);
	sigfillset(&fullset);
	sigdelset(&fullset, SIGINT);
	sigprocmask(SIG_BLOCK, &fullset, NULL);

	/* Get a lock on the passwd file and open it. */
	pw_init();
	for (i = 1; (tfd = pw_lock(0)) == -1; i++) {
		if (i == 4)
			(void)fputs("Attempting to lock password file, "
			    "please wait or press ^C to abort", stderr);
		(void)signal(SIGINT, kbintr);
		if (i % 16 == 0)
			fputc('.', stderr);
		usleep(250000);
		(void)signal(SIGINT, SIG_IGN);
	}
	if (i >= 4)
		fputc('\n', stderr);
	pfd = open(_PATH_MASTERPASSWD, O_RDONLY, 0);
	if (pfd < 0 || fcntl(pfd, F_SETFD, FD_CLOEXEC) == -1)
		pw_error(_PATH_MASTERPASSWD, 1, 1);

	/* Update master.passwd file and rebuild spwd.db. */
	pw_copy(pfd, tfd, pw, opw);
	free(opw);
	if (pw_mkdb(uname, pwflags) < 0)
		pw_error(NULL, 0, 1);

	return(0);
}

char *
getnewpasswd(struct passwd *pw, login_cap_t *lc, int authenticated)
{
	char *p;
	int tries, pwd_tries;
	char buf[_PASSWORD_LEN+1], salt[_PASSWORD_LEN];
	sig_t saveint, savequit;

	saveint = signal(SIGINT, kbintr);
	savequit = signal(SIGQUIT, kbintr);

	if (!authenticated) {
		(void)printf("Changing local password for %s.\n", pw->pw_name);
		if (uid != 0 && pw->pw_passwd[0] != '\0') {
			p = getpass("Old password:");
			if (p == NULL || *p == '\0') {
				(void)printf(UNCHANGED_MSG);
				pw_abort();
				exit(p == NULL ? 1 : 0);
			}
			if (strcmp(crypt(p, pw->pw_passwd), pw->pw_passwd)) {
				errno = EACCES;
				pw_error(NULL, 1, 1);
			}
		}
	}

	pwd_tries = pwd_gettries(lc);

	for (buf[0] = '\0', tries = 0;;) {
		p = getpass("New password:");
		if (p == NULL || *p == '\0') {
			(void)printf(UNCHANGED_MSG);
			pw_abort();
			exit(p == NULL ? 1 : 0);
		}
		if (strcmp(p, "s/key") == 0) {
			printf("That password collides with a system feature. Choose another.\n");
			continue;
		}

		if ((tries++ < pwd_tries || pwd_tries == 0) &&
		    pwd_check(lc, p) == 0)
			continue;
		strlcpy(buf, p, sizeof(buf));
		p = getpass("Retype new password:");
		if (p != NULL && strcmp(buf, p) == 0)
			break;
		(void)printf("Mismatch; try again, EOF to quit.\n");
	}
	if (!pwd_gensalt(salt, _PASSWORD_LEN, lc, 'l')) {
		(void)printf("Couldn't generate salt.\n");
		pw_error(NULL, 0, 0);
	}
	(void)signal(SIGINT, saveint);
	(void)signal(SIGQUIT, savequit);

	return(crypt(buf, salt));
}

/* ARGSUSED */
void
kbintr(int signo)
{
	write(STDOUT_FILENO, "\n", 1);
	write(STDOUT_FILENO, UNCHANGED_MSG, sizeof(UNCHANGED_MSG) - 1);
	_exit(0);
}