pam_modules/krb5/krb5_acct_mgmt.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) 1995, 2012, Oracle and/or its affiliates. All rights reserved.
 */

#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 <shadow.h>

#include "krb5_repository.h"

#define KRB5_AUTOMIGRATE_DATA   "SUNW-KRB5-AUTOMIGRATE-DATA"

#define min(a, b) ((a) < (b) ? (a) : (b))

/*
 * pam_sm_acct_mgmt   main account managment routine.
 */

static int
fetch_princ_entry(
    krb5_module_data_t *kmd,
    char *princ_str,
    kadm5_principal_ent_rec *prent, /* out */
    int debug)

{
    kadm5_ret_t     code;
    krb5_principal      princ = 0;
    char            admin_realm[1024];
    char            kprinc[2*MAXHOSTNAMELEN];
    char            **cpw_services, *password;
    void            *server_handle;
    krb5_context        context;
    kadm5_config_params params;

    password = kmd->password;
    context = kmd->kcontext;

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

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

    if (strlen(password) == 0) {
        krb5_free_principal(context, princ);
        if (debug)
            __pam_log(LOG_AUTH | LOG_DEBUG,
                "PAM-KRB5 (acct): fetch_princ_entry: pwlen=0");
        return (PAM_AUTH_ERR);
    }

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

    (void) memset((char *)&params, 0, sizeof (params));
    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 (acct):  unable to get host based "
            "service name for realm '%s'",
            admin_realm);
        krb5_free_principal(context, princ);
        return (PAM_SYSTEM_ERR);
    }

    code = kadm5_init_with_password(context, kprinc, 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 (acct): fetch_princ_entry: "
                "init_with_pw failed: code = %d", code);
        krb5_free_principal(context, princ);
        return ((code == KADM5_BAD_PASSWORD) ?
            PAM_AUTH_ERR : PAM_SYSTEM_ERR);
    }

    if (_kadm5_get_kpasswd_protocol(server_handle) != KRB5_CHGPWD_RPCSEC) {
        if (debug)
            __pam_log(LOG_AUTH | LOG_DEBUG,
                "PAM-KRB5 (acct): fetch_princ_entry: "
                "non-RPCSEC_GSS chpw server, can't get "
                "princ entry");
        (void) kadm5_destroy(server_handle);
        krb5_free_principal(context, princ);
        return (PAM_SYSTEM_ERR);
    }

    code = kadm5_get_principal(server_handle, princ, prent,
                KADM5_PRINCIPAL_NORMAL_MASK);

    if (code != 0) {
        (void) kadm5_destroy(server_handle);
        krb5_free_principal(context, princ);
        return ((code == KADM5_UNK_PRINC) ?
            PAM_USER_UNKNOWN : PAM_SYSTEM_ERR);
    }

    (void) kadm5_destroy(server_handle);
    krb5_free_principal(context, princ);

    return (PAM_SUCCESS);
}

/*
 * exp_warn
 *
 * Warn the user if their pw is set to expire.
 *
 * We first check to see if the KDC had set any account or password
 * expiration information in the key expiration field.  If this was
 * not set then we must assume that the KDC could be broken and revert
 * to fetching pw/account expiration information from kadm.  We can not
 * determine the difference between broken KDCs that do not send key-exp
 * vs. principals that do not have an expiration policy.  The up-shot
 * is that pam_krb5 will probably not be stacked for acct mgmt if the
 * environment does not have an exp policy, avoiding the second exchange
 * using the kadm protocol.
 */
static int
exp_warn(
    pam_handle_t *pamh,
    char *user,
    krb5_module_data_t *kmd,
    int debug)

{
    int err;
    kadm5_principal_ent_rec prent;
    krb5_timestamp  now, days, expiration;
    char    messages[PAM_MAX_NUM_MSG][PAM_MAX_MSG_SIZE], *password;
    krb5_error_code code;

    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "PAM-KRB5 (acct): exp_warn start: user = '%s'",
            user ? user : "<null>");

    password = kmd->password;

    if (!pamh || !user || !password) {
        err = PAM_SERVICE_ERR;
        goto exit;
    }

    /*
     * If we error out from krb5_init_secure_context, then just set error
     * code, check to see about debug message and exit out of routine as the
     * context could not possibly have been setup.
     */

    if (code = krb5_init_secure_context(&kmd->kcontext)) {
        err = PAM_SYSTEM_ERR;
        if (debug)
            __pam_log(LOG_AUTH | LOG_ERR, "PAM-KRB5 (acct): "
                "krb5_init_secure_context failed: code=%d",
                code);
        goto exit;
    }
    if (code = krb5_timeofday(kmd->kcontext, &now)) {
        err = PAM_SYSTEM_ERR;
        if (debug)
            __pam_log(LOG_AUTH | LOG_ERR,
                "PAM-KRB5 (acct): krb5_timeofday failed: code=%d",
                code);
        goto out;
    }

    if (kmd->expiration != 0) {
        expiration = kmd->expiration;
    } else {
        (void) memset(&prent, 0, sizeof (prent));
        if ((err = fetch_princ_entry(kmd, user, &prent, debug))
            != PAM_SUCCESS) {
            if (debug)
                __pam_log(LOG_AUTH | LOG_DEBUG,
                "PAM-KRB5 (acct): exp_warn: fetch_pr failed %d",
                err);
            goto out;
        }
        if (prent.princ_expire_time != 0 && prent.pw_expiration != 0)
            expiration = min(prent.princ_expire_time,
                prent.pw_expiration);
        else
            expiration = prent.princ_expire_time ?
                prent.princ_expire_time : prent.pw_expiration;
    }

    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "PAM-KRB5 (acct): exp_warn: "
            "princ/pw_exp exp=%ld, now =%ld, days=%ld",
            expiration,
            now,
            expiration > 0
            ? ((expiration - now) / DAY)
            : 0);

    /* warn user if principal's pw is set to expire */
    if (expiration > 0) {
        days = (expiration - now) / DAY;
        if (days <= 0)
            (void) snprintf(messages[0],
                sizeof (messages[0]),
                dgettext(TEXT_DOMAIN,
                "Your Kerberos account/password will expire "
                "within 24 hours.\n"));
        else if (days == 1)
            (void) snprintf(messages[0],
                sizeof (messages[0]),
                dgettext(TEXT_DOMAIN,
                "Your Kerberos account/password will expire "
                "in 1 day.\n"));
        else
            (void) snprintf(messages[0],
                sizeof (messages[0]),
                dgettext(TEXT_DOMAIN,
                "Your Kerberos account/password will expire in "
                "%d days.\n"),
                (int)days);

        (void) __pam_display_msg(pamh, PAM_TEXT_INFO, 1,
                    messages, NULL);
    }

    /* things went smooth */
    err = PAM_SUCCESS;

out:

    if (kmd->kcontext) {
        krb5_free_context(kmd->kcontext);
        kmd->kcontext = NULL;
    }

exit:

    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "PAM-KRB5 (acct): exp_warn end: err = %d", err);

    return (err);
}

/*
 * pam_krb5 acct_mgmt
 *
 * we do
 *    - check if pw expired (flag set in auth)
 *    - warn user if pw is set to expire
 *
 * notes
 *    - we require the auth module to have already run (sets module data)
 *    - we don't worry about an expired princ cuz if that's the case,
 *      auth would have failed
 */
int
pam_sm_acct_mgmt(
    pam_handle_t *pamh,
    int flags,
    int argc,
    const char **argv)

{
    char *user = NULL;
    char *userdata = NULL;
    int err;
    int i;
    krb5_module_data_t *kmd = NULL;
    char    messages[PAM_MAX_NUM_MSG][PAM_MAX_MSG_SIZE];
    int debug = 0;  /* pam.conf entry option */
    int nowarn = 0; /* pam.conf entry option, no expire warnings */
    pam_repository_t    *rep_data = NULL;

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

    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "PAM-KRB5 (acct): debug=%d, nowarn=%d",
            debug, nowarn);

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

    if (rep_data != NULL) {
        /*
         * If the repository is not ours,
         * return PAM_IGNORE.
         */
        if (strcmp(rep_data->type, KRB5_REPOSITORY_NAME) != 0) {
            if (debug)
                __pam_log(LOG_AUTH | LOG_DEBUG,
                    "PAM-KRB5 (acct): wrong"
                    "repository found (%s), returning "
                    "PAM_IGNORE", rep_data->type);
            return (PAM_IGNORE);
        }
    }


    /* get user name */
    (void) pam_get_item(pamh, PAM_USER, (void **) &user);

    if (user == NULL || *user == '\0') {
        err = PAM_USER_UNKNOWN;
        goto out;
    }

    /* get pam_krb5_migrate specific data */
    err = pam_get_data(pamh, KRB5_AUTOMIGRATE_DATA,
                    (const void **)&userdata);
    if (err != PAM_SUCCESS) {
        if (debug)
            __pam_log(LOG_AUTH | LOG_DEBUG, "PAM-KRB5 (acct): "
                "no module data for KRB5_AUTOMIGRATE_DATA");
    } else {
        /*
         * We try and reauthenticate, since this user has a
         * newly created krb5 principal via the pam_krb5_migrate
         * auth module. That way, this new user will have fresh
         * creds (assuming pam_sm_authenticate() succeeds).
         */
        if (strcmp(user, userdata) == 0)
            (void) pam_sm_authenticate(pamh, flags, argc,
                    (const char **)argv);
        else
            if (debug)
                __pam_log(LOG_AUTH | LOG_DEBUG,
                "PAM-KRB5 (acct): PAM_USER %s"
                "does not match user %s from pam_get_data()",
                user, (char *)userdata);
    }

    /* get krb5 module data  */
    if ((err = pam_get_data(pamh, KRB5_DATA, (const void **)&kmd))
        != PAM_SUCCESS) {
        if (err == PAM_NO_MODULE_DATA) {
            /*
             * pam_auth never called (possible config
             * error; no pam_krb5 auth entry in pam.conf),
             */
            if (debug) {
                __pam_log(LOG_AUTH | LOG_DEBUG,
                    "PAM-KRB5 (acct): no module data");
            }
            err = PAM_IGNORE;
            goto out;
        } else {
            __pam_log(LOG_AUTH | LOG_ERR,
                    "PAM-KRB5 (acct): get module"
                    " data failed: err=%d",
                err);
        }
        goto out;
    }

    debug = debug || kmd->debug;

    /*
     * auth mod set status to ignore, most likely cuz root key is
     * in keytab, so skip other checks and return ignore
     */
    if (kmd->auth_status == PAM_IGNORE) {
        if (debug)
            __pam_log(LOG_AUTH | LOG_DEBUG,
                "PAM-KRB5 (acct): kmd auth_status is IGNORE");
        err = PAM_IGNORE;
        goto out;
    }

    /*
     * If there is no Kerberos related user and there is authentication
     * data, this means that while the user has successfully passed
     * authentication, Kerberos is not the account authority because there
     * is no valid Kerberos principal.  PAM_IGNORE is returned since
     * Kerberos is not authoritative for this user.  Other modules in the
     * account stack will need to determine the success or failure for this
     * user.
     */
    if (kmd->auth_status == PAM_USER_UNKNOWN) {
        if (debug)
            syslog(LOG_DEBUG,
                "PAM-KRB5 (acct): kmd auth_status is USER UNKNOWN");
        err = PAM_IGNORE;
        goto out;
    }

    /*
     * age_status will be set to PAM_NEW_AUTHTOK_REQD in pam_krb5's
     * 'auth' if the user's key/pw has expired and needs to be changed
     */
    if (kmd->age_status == PAM_NEW_AUTHTOK_REQD) {
        if (!nowarn) {
            (void) snprintf(messages[0], sizeof (messages[0]),
                dgettext(TEXT_DOMAIN,
                "Your Kerberos password has expired.\n"));
            (void) __pam_display_msg(pamh, PAM_TEXT_INFO,
                    1, messages, NULL);
        }
        err = PAM_NEW_AUTHTOK_REQD;
        goto out;
    }

    if (kmd->auth_status == PAM_SUCCESS && !(flags & PAM_SILENT) &&
        !nowarn && kmd->password) {
        /* if we fail, let it slide, it's only a warning brah */
        (void) exp_warn(pamh, user, kmd, debug);
    }

    /*
     * If Kerberos is treated as optional in the PAM stack, it is possible
     * that there is a KRB5_DATA item and a non-Kerberos account authority.
     * In that case, PAM_IGNORE is returned.
     */
    err = kmd->auth_status != PAM_SUCCESS ? PAM_IGNORE : kmd->auth_status;

out:
    if (debug)
        __pam_log(LOG_AUTH | LOG_DEBUG,
            "PAM-KRB5 (acct): end: %s", pam_strerror(pamh, err));

    return (err);
}