text: /*	$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);
  }
  