Return to pwd_check.c CVS log

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Simplify some things now that we only have login.conf to worry about
and fix two bugs introduced in the last commit (a duplicate free
and reversed logic for the default cipher types).

/*	$OpenBSD: pwd_check.c,v 1.9 2004/07/13 21:29:12 millert Exp $	*/

/*
 * Copyright 2000 Niels Provos <provos@citi.umich.edu>
 * 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. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Niels Provos.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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/wait.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <limits.h>
#include <errno.h>
#include <err.h>
#include <regex.h>
#include <grp.h>
#include <paths.h>
#include <login_cap.h>

struct pattern {
	char *match;
	int flags;
	char *response;
};

struct pattern patterns[] = {
	{
		"^[0-9]*$",
		REG_EXTENDED|REG_NOSUB,
		"Please don't use all-digit passwords."
	},
	{
		"^[a-z]{1,9}$",
		REG_EXTENDED|REG_NOSUB,
		"Please don't use an all-lower case password."
	},
	{
		"^[a-z]{1,6}[0-9]+$",
		REG_EXTENDED|REG_NOSUB|REG_ICASE,
		"Please use a more complicated password."
	},
	{
		"^([a-z][0-9]){1,4}$",
		REG_EXTENDED|REG_NOSUB|REG_ICASE,
		"Please use a more complicated password."
	},
	{
		"^([0-9][a-z]){1,4}$",
		REG_EXTENDED|REG_NOSUB|REG_ICASE,
		"Please use a more complicated password."
	}
};

int
pwd_check(login_cap_t *lc, char *password)
{
	regex_t rgx;
	int i, res, min_len;
	char *checker;
	int pipefds[2];
	pid_t child;

	min_len = (int)login_getcapnum(lc, "minpasswordlen", 6, 6);
	if (min_len > 0 && strlen(password) < min_len) {
		printf("Please enter a longer password.\n");
		return (0);
	}

	for (i = 0; i < sizeof(patterns) / sizeof(struct pattern); i++) {
		if (regcomp(&rgx, patterns[i].match, patterns[i].flags) != 0)
			continue;
		res = regexec(&rgx, password, 0, NULL, 0);
		regfree(&rgx);
		if (!res) {
			printf("%s\nUnusual capitalization, control characters or digits are suggested.\n", patterns[i].response);
			return (0);
		}
	}

	/* If no external checker is specified, just accept the password */
	checker = login_getcapstr(lc, "passwordcheck", NULL, NULL);
	if (checker == NULL)
		return (1);

	/* Okay, now pass control to an external program */
	if (pipe(pipefds) == -1) {
		warn("pipe");
		goto out;
	}

	child = fork();
	if (child == 0) {
		char *argp[] = { "sh", "-c", NULL, NULL};

		/* Drop privileges */
		seteuid(getuid());
		setuid(getuid());

		if (dup2(pipefds[0], STDIN_FILENO) == -1)
			exit(1);

		close(pipefds[0]);
		close(pipefds[1]);

		argp[2] = checker;
		if (execv(_PATH_BSHELL, argp) == -1)
			exit(1);
		/* NOT REACHED */
	} else if (child == -1) {
		warn("fork");
		goto out;
	}
	close(pipefds[0]);

	/* Send the password to STDIN of child */
	write(pipefds[1], password, strlen(password) + 1);
	close(pipefds[1]);

	/* get the return value from the child */
	wait(&child);
	if (WIFEXITED(child) && WEXITSTATUS(child) == 0) {
		free(checker);
		return (1);
	}

 out:
	free(checker);
	printf("Please use a different password. Unusual capitalization,\n");
	printf("control characters, or digits are suggested.\n");
	return (0);
}

int
pwd_gettries(login_cap_t *lc)
{
	quad_t ntries;

	if ((ntries = login_getcapnum(lc, "passwordtries", -1, -1)) != -1) {
		if (ntries > 0 && ntries <= INT_MAX)
			return((int)ntries);
		fprintf(stderr,
		    "Warning: pwdtries out of range in /etc/login.conf");
	}

	/*
	 * If no amount of tries is specified, return a default of 3,
	 * meaning that after 3 attempts where the user is foiled by the
	 * password checks, it will no longer be checked and they can set
	 * it to whatever they like.  This is the historic BSD behavior.
	 */
	return (3);
}