Ignore password attributes for S4U2Self requests

For consistency with Windows KDCs, allow protocol transition to work
even if the password has expired or needs changing.

Also, when looking up an enterprise principal with an AS request,
treat ERR_KEY_EXP as confirmation that the client is present in the
realm.

[ghudson@mit.edu: added comment in kdc_process_s4u2self_req(); edited
commit message]

ticket: 8763 (new)
tags: pullup
target_version: 1.17
validate_as_request(kdc_realm_t *kdc_active_realm,
                    krb5_kdc_req *request, krb5_db_entry client,
                    krb5_db_entry server, krb5_timestamp kdc_time,
                    const char **status, krb5_pa_data ***e_data)
{
    krb5_error_code ret;

    /*
     * If an option is set that is only allowed in TGS requests, complain.
     */
    if (request->kdc_options & AS_INVALID_OPTIONS) {
        *status = "INVALID AS OPTIONS";
        return KDC_ERR_BADOPTION;
    }

    /* The client must not be expired */
    if (client.expiration && ts_after(kdc_time, client.expiration)) {
        *status = "CLIENT EXPIRED";
        if (vague_errors)
            return(KRB_ERR_GENERIC);
        else
            return(KDC_ERR_NAME_EXP);
    }

    /* The client's password must not be expired, unless the server is
       a KRB5_KDC_PWCHANGE_SERVICE. */
    if (client.pw_expiration && ts_after(kdc_time, client.pw_expiration) &&
        !isflagset(server.attributes, KRB5_KDB_PWCHANGE_SERVICE)) {
        *status = "CLIENT KEY EXPIRED";
        if (vague_errors)
            return(KRB_ERR_GENERIC);
        else
            return(KDC_ERR_KEY_EXP);
    }

    /* The server must not be expired */
    if (server.expiration && ts_after(kdc_time, server.expiration)) {
        *status = "SERVICE EXPIRED";
        return(KDC_ERR_SERVICE_EXP);
    }

    /*
     * If the client requires password changing, then only allow the
     * pwchange service.
     */
    if (isflagset(client.attributes, KRB5_KDB_REQUIRES_PWCHANGE) &&
        !isflagset(server.attributes, KRB5_KDB_PWCHANGE_SERVICE)) {
        *status = "REQUIRED PWCHANGE";
        return(KDC_ERR_KEY_EXP);
    }

    /* Client and server must allow postdating tickets */
    if ((isflagset(request->kdc_options, KDC_OPT_ALLOW_POSTDATE) ||
         isflagset(request->kdc_options, KDC_OPT_POSTDATED)) &&
        (isflagset(client.attributes, KRB5_KDB_DISALLOW_POSTDATED) ||
         isflagset(server.attributes, KRB5_KDB_DISALLOW_POSTDATED))) {
        *status = "POSTDATE NOT ALLOWED";
        return(KDC_ERR_CANNOT_POSTDATE);
    }

    /* Check to see if client is locked out */
    if (isflagset(client.attributes, KRB5_KDB_DISALLOW_ALL_TIX)) {
        *status = "CLIENT LOCKED OUT";
        return(KDC_ERR_CLIENT_REVOKED);
    }

    /* Check to see if server is locked out */
    if (isflagset(server.attributes, KRB5_KDB_DISALLOW_ALL_TIX)) {
        *status = "SERVICE LOCKED OUT";
        return(KDC_ERR_S_PRINCIPAL_UNKNOWN);
    }

    /* Check to see if server is allowed to be a service */
    if (isflagset(server.attributes, KRB5_KDB_DISALLOW_SVR)) {
        *status = "SERVICE NOT ALLOWED";
        return(KDC_ERR_MUST_USE_USER2USER);
    }

    if (check_anon(kdc_active_realm, client.princ, request->server) != 0) {
        *status = "ANONYMOUS NOT ALLOWED";
        return(KDC_ERR_POLICY);
    }

    /* Perform KDB module policy checks. */
    ret = krb5_db_check_policy_as(kdc_context, request, &client, &server,
                                  kdc_time, status, e_data);
    if (ret && ret != KRB5_PLUGIN_OP_NOTSUPP)
        return errcode_to_protocol(ret);

    return 0;
}

validate_as_request(kdc_realm_t *kdc_active_realm,
                    krb5_kdc_req *request, krb5_db_entry client,
                    krb5_db_entry server, krb5_timestamp kdc_time,
                    const char **status, krb5_pa_data ***e_data)
{
    krb5_error_code ret;

    /*
     * If an option is set that is only allowed in TGS requests, complain.
     */
    if (request->kdc_options & AS_INVALID_OPTIONS) {
        *status = "INVALID AS OPTIONS";
        return KDC_ERR_BADOPTION;
    }

    /* The client must not be expired */
    if (client.expiration && ts_after(kdc_time, client.expiration)) {
        *status = "CLIENT EXPIRED";
        if (vague_errors)
            return(KRB_ERR_GENERIC);
        else
            return(KDC_ERR_NAME_EXP);
    }

    /* The client's password must not be expired, unless the server is
       a KRB5_KDC_PWCHANGE_SERVICE. */
    if (client.pw_expiration && ts_after(kdc_time, client.pw_expiration) &&
        !isflagset(server.attributes, KRB5_KDB_PWCHANGE_SERVICE)) {
        *status = "CLIENT KEY EXPIRED";
        if (vague_errors)
            return(KRB_ERR_GENERIC);
        else
            return(KDC_ERR_KEY_EXP);
    }

    /* The server must not be expired */
    if (server.expiration && ts_after(kdc_time, server.expiration)) {
        *status = "SERVICE EXPIRED";
        return(KDC_ERR_SERVICE_EXP);
    }

    /*
     * If the client requires password changing, then only allow the
     * pwchange service.
     */
    if (isflagset(client.attributes, KRB5_KDB_REQUIRES_PWCHANGE) &&
        !isflagset(server.attributes, KRB5_KDB_PWCHANGE_SERVICE)) {
        *status = "REQUIRED PWCHANGE";
        return(KDC_ERR_KEY_EXP);
    }

    /* Client and server must allow postdating tickets */
    if ((isflagset(request->kdc_options, KDC_OPT_ALLOW_POSTDATE) ||
         isflagset(request->kdc_options, KDC_OPT_POSTDATED)) &&
        (isflagset(client.attributes, KRB5_KDB_DISALLOW_POSTDATED) ||
         isflagset(server.attributes, KRB5_KDB_DISALLOW_POSTDATED))) {
        *status = "POSTDATE NOT ALLOWED";
        return(KDC_ERR_CANNOT_POSTDATE);
    }

    /* Check to see if client is locked out */
    if (isflagset(client.attributes, KRB5_KDB_DISALLOW_ALL_TIX)) {
        *status = "CLIENT LOCKED OUT";
        return(KDC_ERR_CLIENT_REVOKED);
    }

    /* Check to see if server is locked out */
    if (isflagset(server.attributes, KRB5_KDB_DISALLOW_ALL_TIX)) {
        *status = "SERVICE LOCKED OUT";
        return(KDC_ERR_S_PRINCIPAL_UNKNOWN);
    }

    /* Check to see if server is allowed to be a service */
    if (isflagset(server.attributes, KRB5_KDB_DISALLOW_SVR)) {
        *status = "SERVICE NOT ALLOWED";
        return(KDC_ERR_MUST_USE_USER2USER);
    }

    if (check_anon(kdc_active_realm, client.princ, request->server) != 0) {
        *status = "ANONYMOUS NOT ALLOWED";
        return(KDC_ERR_POLICY);
    }

    /* Perform KDB module policy checks. */
    ret = krb5_db_check_policy_as(kdc_context, request, &client, &server,
                                  kdc_time, status, e_data);
    if (ret && ret != KRB5_PLUGIN_OP_NOTSUPP)
        return errcode_to_protocol(ret);

    return 0;
}
