320 lines
8.1 KiB
C
320 lines
8.1 KiB
C
/*-
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* Copyright (c) 2012-2013 The University of Oslo
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. The name of the author may not be used to endorse or promote
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* products derived from this software without specific prior written
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* permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* $Id$
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <fcntl.h>
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#include <limits.h>
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#include <pwd.h>
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#include <stdint.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#define PAM_SM_AUTH
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#define PAM_SM_ACCOUNT
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#include <security/pam_modules.h>
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#include <security/pam_appl.h>
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#include <security/oath.h>
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#define PAM_OATH_PROMPT "Verification code: "
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#define PAM_OATH_HOTP_WINDOW 3
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#define PAM_OATH_TOTP_WINDOW 3
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enum pam_oath_nokey { nokey_error = -1, nokey_fail, nokey_fake, nokey_ignore };
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static const char *pam_oath_default_keyfile = "/var/oath/%u.otpauth";
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/*
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* Parse the nokey or badkey option, which indicates how we should act if
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* the user has no keyfile or the keyfile is invalid.
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*/
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static enum pam_oath_nokey
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pam_oath_nokey_option(pam_handle_t *pamh, const char *option)
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{
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const char *value;
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if ((value = openpam_get_option(pamh, option)) == NULL)
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return (nokey_fail);
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else if (strcmp(value, "fail") == 0)
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return (nokey_fail);
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else if (strcmp(value, "fake") == 0)
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return (nokey_fake);
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else if (strcmp(value, "ignore") == 0)
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return (nokey_ignore);
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openpam_log(PAM_LOG_ERROR, "the value of the %s option "
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"must be either 'fail', 'fake' or 'ignore'", option);
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return (nokey_error);
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}
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/*
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* Parse a numeric option. Returns -1 if the option is not set or its
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* value is not an integer in the range [0, INT_MAX].
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*/
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static int
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pam_oath_int_option(pam_handle_t *pamh, const char *option)
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{
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const char *value;
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char *end;
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long num;
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if ((value = openpam_get_option(pamh, option)) == NULL)
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return (-1);
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num = strtol(value, &end, 10);
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if (*value == '\0' || *end != '\0' || num < 0 || num > INT_MAX) {
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openpam_log(PAM_LOG_ERROR, "the value of the %s option "
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"is invalid.", option);
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return (-1);
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}
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return (num);
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}
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/*
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* Determine the location of the user's keyfile.
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*/
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static char *
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pam_oath_keyfile(pam_handle_t *pamh)
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{
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const char *keyfile;
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char *path;
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size_t size;
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if ((keyfile = openpam_get_option(pamh, "keyfile")) == NULL)
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keyfile = pam_oath_default_keyfile;
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size = 0;
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if (openpam_subst(pamh, NULL, &size, keyfile) != PAM_TRY_AGAIN)
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return (NULL);
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if ((path = malloc(size)) == NULL)
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return (NULL);
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if (openpam_subst(pamh, path, &size, keyfile) != PAM_SUCCESS) {
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free(path);
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return (NULL);
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}
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return (path);
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}
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/*
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* Load the user's key.
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*/
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static struct oath_key *
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pam_oath_load_key(const char *keyfile)
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{
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/* XXX should check ownership and permissions */
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return (oath_key_from_file(keyfile));
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}
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/*
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* Save the user's key.
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* XXX should be a liboath API function.
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*/
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static int
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pam_oath_save_key(const struct oath_key *key, const char *keyfile)
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{
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char *keyuri;
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int fd, len, pam_err;
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keyuri = NULL;
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len = 0;
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fd = -1;
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pam_err = PAM_SYSTEM_ERR;
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if ((keyuri = oath_key_to_uri(key)) == NULL)
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goto done;
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len = strlen(keyuri);
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if ((fd = open(keyfile, O_WRONLY|O_CREAT|O_TRUNC, 0600)) < 0 ||
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write(fd, keyuri, len) != len || write(fd, "\n", 1) != 1) {
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openpam_log(PAM_LOG_ERROR, "%s: %m", keyfile);
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goto done;
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}
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pam_err = PAM_SUCCESS;
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done:
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if (fd >= 0)
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close(fd);
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if (keyfile != NULL) {
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memset(keyuri, 0, len);
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free(keyuri);
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}
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return (pam_err);
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}
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PAM_EXTERN int
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pam_sm_authenticate(pam_handle_t *pamh, int flags,
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int argc, const char *argv[])
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{
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enum pam_oath_nokey nokey, badkey;
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struct passwd *pwd;
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const char *user, *password;
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char *end, *keyfile;
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struct oath_key *key;
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unsigned long response;
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int pam_err, ret, window;
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/* unused */
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(void)flags;
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(void)argc;
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(void)argv;
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keyfile = NULL;
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key = NULL;
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openpam_log(PAM_LOG_VERBOSE, "attempting OATH authentication");
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/* check how to behave if the user does not have a valid key */
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if ((nokey = pam_oath_nokey_option(pamh, "nokey")) == nokey_error ||
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(badkey = pam_oath_nokey_option(pamh, "badkey")) == nokey_error) {
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pam_err = PAM_SERVICE_ERR;
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goto done;
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}
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/* identify user */
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if ((pam_err = pam_get_user(pamh, &user, NULL)) != PAM_SUCCESS)
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goto done;
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if ((pwd = getpwnam(user)) == NULL) {
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pam_err = PAM_USER_UNKNOWN;
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goto done;
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}
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openpam_log(PAM_LOG_VERBOSE, "authenticating user %s", user);
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/* load key */
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if ((keyfile = pam_oath_keyfile(pamh)) == NULL) {
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pam_err = PAM_SYSTEM_ERR;
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goto done;
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}
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openpam_log(PAM_LOG_VERBOSE, "attempting to load %s for %s", keyfile, user);
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key = pam_oath_load_key(keyfile);
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/*
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* The user doesn't have a key, should we fake it?
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*
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* XXX implement badkey - currently, oath_key_from_file() doesn't
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* provide enough information for us to tell the difference
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* between a bad key and no key at all.
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*
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* XXX move this into pam_oath_load_key()
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*/
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if (key == NULL) {
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openpam_log(PAM_LOG_VERBOSE, "no key found for %s", user);
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switch (nokey) {
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case nokey_fail:
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pam_err = PAM_AUTHINFO_UNAVAIL;
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goto done;
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case nokey_fake:
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key = oath_key_dummy(om_hotp, oh_sha1, 6);
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break;
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case nokey_ignore:
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pam_err = PAM_IGNORE;
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goto done;
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default:
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/* can't happen */
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pam_err = PAM_SERVICE_ERR;
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goto done;
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}
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}
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/* get user's response */
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pam_err = pam_get_authtok(pamh, PAM_AUTHTOK,
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&password, PAM_OATH_PROMPT);
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if (pam_err != PAM_SUCCESS) {
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openpam_log(PAM_LOG_VERBOSE, "conversation failure");
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goto done;
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}
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/* convert to number */
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response = strtoul(password, &end, 10);
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if (end == password || *end != '\0')
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response = ULONG_MAX;
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/* verify response */
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if (key->mode == om_hotp) {
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if ((window = pam_oath_int_option(pamh, "hotp_window")) < 0 &&
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(window = pam_oath_int_option(pamh, "window")) < 0)
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window = PAM_OATH_HOTP_WINDOW;
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ret = oath_hotp_match(key, response, window);
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} else {
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if ((window = pam_oath_int_option(pamh, "totp_window")) < 0 &&
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(window = pam_oath_int_option(pamh, "window")) < 0)
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window = PAM_OATH_TOTP_WINDOW;
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ret = oath_totp_match(key, response, window);
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}
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openpam_log(PAM_LOG_VERBOSE, "verification code %s",
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ret > 0 ? "matched" : "did not match");
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if (ret <= 0) {
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pam_err = ret < 0 ? PAM_SERVICE_ERR : PAM_AUTH_ERR;
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goto done;
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}
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/* write back the key (update counter for HOTP, lastused for TOTP) */
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if (pam_oath_save_key(key, keyfile) != 0) {
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pam_err = PAM_SERVICE_ERR;
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goto done;
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}
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openpam_log(PAM_LOG_VERBOSE, "OATH authentication succeeded");
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pam_err = PAM_SUCCESS;
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done:
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oath_key_free(key);
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free(keyfile);
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return (pam_err);
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}
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PAM_EXTERN int
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pam_sm_setcred(pam_handle_t *pamh, int flags,
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int argc, const char *argv[])
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{
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/* unused */
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(void)pamh;
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(void)flags;
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(void)argc;
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(void)argv;
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return (PAM_SUCCESS);
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}
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PAM_EXTERN int
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pam_sm_acct_mgmt(pam_handle_t *pamh, int flags,
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int argc, const char *argv[])
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{
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/* unused */
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(void)pamh;
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(void)flags;
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(void)argc;
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(void)argv;
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return (PAM_SUCCESS);
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}
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PAM_MODULE_ENTRY("pam_unix");
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