pam_modules/krb5/krb5_password.c

/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License (the "License").
 * You may not use this file except in compliance with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */

/*
 * Copyright (c) 1997, 2012, Oracle and/or its affiliates. All rights reserved.
 */

#include <k5-int.h>
#include <kadm5/admin.h>
#include <krb5.h>

#include <security/pam_appl.h>
#include <security/pam_modules.h>
#include <security/pam_impl.h>
#include <syslog.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <pwd.h>
#include <libintl.h>
#include <netdb.h>
#include "utils.h"
#include "krb5_repository.h"

extern int attempt_krb5_auth(pam_handle_t *, krb5_module_data_t *, char *,
    char **, boolean_t);
extern int krb5_verifypw(char *, char *, int);

static void display_msg(pam_handle_t *, int, char *);
static void display_msgs(pam_handle_t *, int, int,
        char msgs[][PAM_MAX_MSG_SIZE]);
static int krb5_changepw(pam_handle_t *, char *, char *, char *, int);

/*
 * set_ccname()
 *
 * set KRB5CCNAME shell var
 */
static void
set_ccname(
    pam_handle_t *pamh,
    krb5_module_data_t *kmd,
    int login_result,
    int debug)
{
    int result;

    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "PAM-KRB5 (password): password: finalize"
            " ccname env, login_result =%d, env ='%s'",
            login_result, kmd->env ? kmd->env : "<null>");

    if (kmd->env) {

        if (login_result == PAM_SUCCESS) {
                /*
                 * Put ccname into the pamh so that login
                 * apps can pick this up when they run
                 * pam_getenvlist().
                 */
            if ((result = pam_putenv(pamh, kmd->env))
                != PAM_SUCCESS) {
                /* should not happen but... */
                __pam_log(LOG_AUTH | LOG_ERR,
                    "PAM-KRB5 (password):"
                    " pam_putenv failed: result: %d",
                    result);
                goto cleanupccname;
            }
        } else {
        cleanupccname:
                /* for lack of a Solaris unputenv() */
            krb5_unsetenv(KRB5_ENV_CCNAME);
            free(kmd->env);
            kmd->env = NULL;
        }
    }
}

/*
 * get_set_creds()
 *
 * do a krb5 login to get and set krb5 creds (needed after a pw change
 * on pw expire on login)
 */
static void
get_set_creds(
    pam_handle_t *pamh,
    krb5_module_data_t *kmd,
    char *user,
    char *newpass,
    int debug)
{
    int login_result;

    if (!kmd || kmd->age_status != PAM_NEW_AUTHTOK_REQD)
        return;

    /*
     * if pw has expired, get/set krb5 creds ala auth mod
     *
     * pwchange verified user sufficiently, so don't request strict
     * tgt verification (will cause rcache perm issues possibly anyways)
     */
    login_result = attempt_krb5_auth(pamh, kmd, user, &newpass, 0);
    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "PAM-KRB5 (password): get_set_creds: login_result= %d",
            login_result);
    /*
     * the krb5 login should not fail, but if so,
     * warn the user they have to kinit(1)
     */
    if (login_result != PAM_SUCCESS) {
        display_msg(pamh, PAM_TEXT_INFO,
            dgettext(TEXT_DOMAIN,
            "Warning: "
            "Could not cache Kerberos"
            " credentials, please run "
            "kinit(1) or re-login\n"));
    }
    set_ccname(pamh, kmd, login_result, debug);
}
/*
 * This is the PAM Kerberos Password Change module
 *
 */

int
pam_sm_chauthtok(
    pam_handle_t        *pamh,
    int         flags,
    int         argc,
    const char      **argv)
{

    char            *user;
    int         err, result = PAM_AUTHTOK_ERR;
    char            *newpass = NULL;
    char            *oldpass = NULL;
    int         i;
    int         debug = 0;
    uid_t           pw_uid;
    krb5_module_data_t  *kmd = NULL;
    pam_repository_t    *rep_data = NULL;

    for (i = 0; i < argc; i++) {
        if (strcmp(argv[i], "debug") == 0)
            debug = 1;
        else
            __pam_log(LOG_AUTH | LOG_ERR,
                "PAM-KRB5 (password): illegal option %s",
                argv[i]);
    }

    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "PAM-KRB5 (password): start: flags = %x",
            flags);

    (void) pam_get_item(pamh, PAM_REPOSITORY, (void **)&rep_data);

    if (rep_data != NULL) {
        if (strcmp(rep_data->type, KRB5_REPOSITORY_NAME) != 0) {
            if (debug)
                __pam_log(LOG_AUTH | LOG_DEBUG,
                    "PAM-KRB5 (auth): wrong"
                    "repository found (%s), returning "
                    "PAM_IGNORE", rep_data->type);
            return (PAM_IGNORE);
        }
    }

    if (flags & PAM_PRELIM_CHECK) {
        /* Nothing to do here */
        if (debug)
            __pam_log(LOG_AUTH | LOG_DEBUG,
                "PAM-KRB5 (password): prelim check");
        return (PAM_IGNORE);
    }

    /* make sure PAM framework is telling us to update passwords */
    if (!(flags & PAM_UPDATE_AUTHTOK)) {
        __pam_log(LOG_AUTH | LOG_ERR,
            "PAM-KRB5 (password): bad flags: %d",
            flags);
        return (PAM_SYSTEM_ERR);
    }


    if ((err = pam_get_data(pamh, KRB5_DATA, (const void **)&kmd))
        != PAM_SUCCESS) {
        if (debug)
            __pam_log(LOG_AUTH | LOG_DEBUG,
                "PAM-KRB5 (password): get mod data failed %d",
                err);
        kmd = NULL;
    }

    if (flags & PAM_CHANGE_EXPIRED_AUTHTOK) {
        /* let's make sure we know the krb5 pw has expired */

        if (debug)
            __pam_log(LOG_AUTH | LOG_DEBUG,
                "PAM-KRB5 (password): kmd age status %d",
                kmd ? kmd->age_status : -99);

        if (!kmd || kmd->age_status != PAM_NEW_AUTHTOK_REQD)
            return (PAM_IGNORE);
    }

    (void) pam_get_item(pamh, PAM_USER, (void **)&user);

    if (user == NULL || *user == '\0') {
        __pam_log(LOG_AUTH | LOG_ERR,
            "PAM-KRB5 (password): username is empty");
        return (PAM_USER_UNKNOWN);
    }

    if (!get_pw_uid(user, &pw_uid)) {
        __pam_log(LOG_AUTH | LOG_ERR,
            "PAM-KRB5 (password): can't get uid for %s", user);
        return (PAM_USER_UNKNOWN);
    }

    /*
     * if root key exists in the keytab, it's a random key so no
     * need to prompt for pw and we just return IGNORE
     */
    if ((strcmp(user, ROOT_UNAME) == 0) &&
        key_in_keytab(user, debug)) {
        if (debug)
            __pam_log(LOG_AUTH | LOG_DEBUG,
                "PAM-KRB5 (password): "
                "key for '%s' in keytab, returning IGNORE", user);
        result = PAM_IGNORE;
        goto out;
    }

    (void) pam_get_item(pamh, PAM_AUTHTOK, (void **)&newpass);

    /*
     * If the preauth type done didn't use a passwd just ignore the error.
     */
    if (newpass == NULL)
        if (kmd && kmd->preauth_type == KRB_PKINIT)
            return (PAM_IGNORE);
        else
            return (PAM_SYSTEM_ERR);

    (void) pam_get_item(pamh, PAM_OLDAUTHTOK, (void **)&oldpass);

    if (oldpass == NULL)
        if (kmd && kmd->preauth_type == KRB_PKINIT)
            return (PAM_IGNORE);
        else
            return (PAM_SYSTEM_ERR);

    result = krb5_verifypw(user, oldpass, debug);
    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "PAM-KRB5 (password): verifypw %d", result);

    /*
     * If it's a bad password or general failure, we are done.
     */
    if (result != 0) {
        /*
         * if the preauth type done didn't use a passwd just ignore the
         * error.
         */
        if (kmd && kmd->preauth_type == KRB_PKINIT)
            return (PAM_IGNORE);

        if (result == 2)
            display_msg(pamh, PAM_ERROR_MSG, dgettext(TEXT_DOMAIN,
                "Old Kerberos password incorrect\n"));
        return (PAM_AUTHTOK_ERR);
    }

    /*
     * If the old password verifies try to change it regardless of the
     * preauth type and do not ignore the error.
     */
    result = krb5_changepw(pamh, user, oldpass, newpass, debug);
    if (result == PAM_SUCCESS) {
        display_msg(pamh, PAM_TEXT_INFO, dgettext(TEXT_DOMAIN,
            "Kerberos password successfully changed\n"));

        get_set_creds(pamh, kmd, user, newpass, debug);
    }

out:
    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "PAM-KRB5 (password): out: returns %d",
            result);

    return (result);
}

int
krb5_verifypw(
    char    *princ_str,
    char    *old_password,
    int debug)
{
    kadm5_ret_t     code;
    krb5_principal      princ = 0;
    char            admin_realm[1024];
    char            kprinc[2*MAXHOSTNAMELEN];
    char            **cpw_services;
    void            *server_handle;
    krb5_context        context;
    kadm5_config_params params;

    (void) memset((char *)&params, 0, sizeof (params));

    if (code = krb5_init_secure_context(&context)) {
        return (6);
    }

    if ((code = get_kmd_kuser(context, (const char *)princ_str, kprinc,
        2*MAXHOSTNAMELEN)) != 0) {
        return (code);
    }

    /* Need to get a krb5_principal struct */

    code = krb5_parse_name(context, kprinc, &princ);

    if (code != 0)
        return (6);

    if (strlen(old_password) == 0) {
        krb5_free_principal(context, princ);
        return (5);
    }

    (void) strlcpy(admin_realm,
        krb5_princ_realm(context, princ)->data,
        sizeof (admin_realm));

    params.mask |= KADM5_CONFIG_REALM;
    params.realm = admin_realm;


    if (kadm5_get_cpw_host_srv_names(context, admin_realm, &cpw_services)) {
        __pam_log(LOG_AUTH | LOG_ERR,
            "PAM-KRB5 (password): unable to get host based "
            "service name for realm %s\n",
            admin_realm);
        krb5_free_principal(context, princ);
        return (3);
    }

    code = kadm5_init_with_password(context, kprinc, old_password,
        cpw_services, &params, KADM5_STRUCT_VERSION,
        KADM5_API_VERSION_2, NULL,
        &server_handle);
    free_srv_names(cpw_services);
    if (code != 0) {
        if (debug)
            __pam_log(LOG_AUTH | LOG_DEBUG,
                "PAM-KRB5: krb5_verifypw: init_with_pw"
                " failed: (%s)", error_message(code));
        krb5_free_principal(context, princ);
        return ((code == KADM5_BAD_PASSWORD) ? 2 : 3);
    }

    krb5_free_principal(context, princ);

    (void) kadm5_destroy(server_handle);

    return (0);
}

/*
 * Function: krb5_changepw
 *
 * Purpose: Initialize and call lower level routines to change a password
 *
 * Arguments:
 *
 *  princ_str   principal name to use, optional
 *  old_password    old password
 *  new_password    new password
 *
 * Returns:
 *                      exit status of PAM_SUCCESS for success
 *          else returns PAM failure
 *
 * Requires:
 *  Passwords cannot be more than 255 characters long.
 *
 * Modifies:
 *
 * Changes the principal's password.
 *
 */
static int
krb5_changepw(
    pam_handle_t *pamh,
    char *princ_str,
    char *old_password,
    char *new_password,
    int debug)
{
    kadm5_ret_t     code;
    krb5_principal      princ = 0;
    char            msg_ret[1024], admin_realm[1024];
    char            kprinc[2*MAXHOSTNAMELEN];
    char            **cpw_services;
    void            *server_handle;
    krb5_context        context;
    kadm5_config_params params;

    (void) memset((char *)&params, 0, sizeof (params));

    if (krb5_init_secure_context(&context) != 0)
        return (PAM_SYSTEM_ERR);

    if ((code = get_kmd_kuser(context, (const char *)princ_str, kprinc,
        2*MAXHOSTNAMELEN)) != 0) {
        return (code);
    }

    /* Need to get a krb5_principal struct */

    code = krb5_parse_name(context, kprinc, &princ);
    if (code != 0)
        return (PAM_SYSTEM_ERR);

    if (strlen(old_password) == 0) {
        krb5_free_principal(context, princ);
        return (PAM_AUTHTOK_ERR);
    }

    (void) snprintf(admin_realm, sizeof (admin_realm), "%s",
        krb5_princ_realm(context, princ)->data);
    params.mask |= KADM5_CONFIG_REALM;
    params.realm = admin_realm;


    if (kadm5_get_cpw_host_srv_names(context, admin_realm, &cpw_services)) {
        __pam_log(LOG_AUTH | LOG_ERR,
            "PAM-KRB5 (password):unable to get host based "
            "service name for realm %s\n",
            admin_realm);
        return (PAM_SYSTEM_ERR);
    }

    code = kadm5_init_with_password(context, kprinc, old_password,
        cpw_services, &params, KADM5_STRUCT_VERSION,
        KADM5_API_VERSION_2, NULL,
        &server_handle);
    free_srv_names(cpw_services);
    if (code != 0) {
        if (debug)
            __pam_log(LOG_AUTH | LOG_DEBUG,
                "PAM-KRB5 (password): changepw: "
                "init_with_pw failed:  (%s)", error_message(code));
        krb5_free_principal(context, princ);
        return ((code == KADM5_BAD_PASSWORD) ?
            PAM_AUTHTOK_ERR : PAM_SYSTEM_ERR);
    }

    code = kadm5_chpass_principal_util(server_handle, princ,
        new_password,
        NULL /* don't need pw back */,
        msg_ret,
        sizeof (msg_ret));

    if (code) {
        char msgs[2][PAM_MAX_MSG_SIZE];

        (void) snprintf(msgs[0], PAM_MAX_MSG_SIZE, "%s",
            dgettext(TEXT_DOMAIN,
            "Kerberos password not changed: "));
        (void) snprintf(msgs[1], PAM_MAX_MSG_SIZE, "%s", msg_ret);

        display_msgs(pamh, PAM_ERROR_MSG, 2, msgs);
    }

    krb5_free_principal(context, princ);

    (void) kadm5_destroy(server_handle);

    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "PAM-KRB5 (password): changepw: end %d", code);

    if (code != 0)
        return (PAM_AUTHTOK_ERR);

    return (PAM_SUCCESS);
}

static void
display_msgs(pam_handle_t *pamh,
    int msg_style, int nmsg, char msgs[][PAM_MAX_MSG_SIZE])
{
    (void) __pam_display_msg(pamh, msg_style, nmsg, msgs, NULL);
}


static void
display_msg(pam_handle_t *pamh, int msg_style, char *msg)
{
    char pam_msg[1][PAM_MAX_MSG_SIZE];

    (void) snprintf(pam_msg[0], PAM_MAX_MSG_SIZE, "%s", msg);
    display_msgs(pamh, msg_style, 1, pam_msg);
}