krb5/krb/chpw.c

/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
** set password functions added by Paul W. Nelson, Thursby Software Systems, Inc.
*/
#include <string.h>

#include "k5-int.h"
#include "auth_con.h"


krb5_error_code
krb5int_mk_chpw_req(krb5_context context,
                    krb5_auth_context auth_context,
                    krb5_data *ap_req,
                    char *passwd,
                    krb5_data *packet)
{
    krb5_error_code ret = 0;
    krb5_data clearpw;
    krb5_data cipherpw;
    krb5_replay_data replay;
    char *ptr;

    cipherpw.data = NULL;

    if ((ret = krb5_auth_con_setflags(context, auth_context,
                                      KRB5_AUTH_CONTEXT_DO_SEQUENCE)))
        goto cleanup;

    clearpw.length = strlen(passwd);
    clearpw.data = passwd;

    if ((ret = krb5_mk_priv(context, auth_context,
                            &clearpw, &cipherpw, &replay)))
        goto cleanup;

    packet->length = 6 + ap_req->length + cipherpw.length;
    packet->data = (char *) malloc(packet->length);
    if (packet->data == NULL) {
        ret = ENOMEM;
        goto cleanup;
    }
    ptr = packet->data;

    /* length */

    store_16_be(packet->length, ptr);
    ptr += 2;

    /* version == 0x0001 big-endian */

    *ptr++ = 0;
    *ptr++ = 1;

    /* ap_req length, big-endian */

    store_16_be(ap_req->length, ptr);
    ptr += 2;

    /* ap-req data */

    memcpy(ptr, ap_req->data, ap_req->length);
    ptr += ap_req->length;

    /* krb-priv of password */

    memcpy(ptr, cipherpw.data, cipherpw.length);

cleanup:
    if (cipherpw.data != NULL)  /* allocated by krb5_mk_priv */
        free(cipherpw.data);

    return(ret);
}

krb5_error_code
krb5int_rd_chpw_rep(krb5_context context, krb5_auth_context auth_context,
                    krb5_data *packet, int *result_code, krb5_data *result_data)
{
    char *ptr;
    int plen, vno;
    krb5_data ap_rep;
    krb5_ap_rep_enc_part *ap_rep_enc;
    krb5_error_code ret;
    krb5_data cipherresult;
    krb5_data clearresult;
    krb5_error *krberror = NULL;
    krb5_replay_data replay;
    krb5_keyblock *tmp;

    if (packet->length < 4)
        /* either this, or the server is printing bad messages,
           or the caller passed in garbage */
        return(KRB5KRB_AP_ERR_MODIFIED);

    ptr = packet->data;

    /* verify length */

    plen = (*ptr++ & 0xff);
    plen = (plen<<8) | (*ptr++ & 0xff);

    if (plen != packet->length) {
        /*
         * MS KDCs *may* send back a KRB_ERROR.  Although
         * not 100% correct via RFC3244, it's something
         * we can workaround here.
         */
        if (krb5_is_krb_error(packet)) {

            if ((ret = krb5_rd_error(context, packet, &krberror)))
                return(ret);

            if (krberror->e_data.data  == NULL)
                ret = ERROR_TABLE_BASE_krb5 + (krb5_error_code) krberror->error;
            else
                ret = KRB5KRB_AP_ERR_MODIFIED;
            krb5_free_error(context, krberror);
            return(ret);
        } else {
            return(KRB5KRB_AP_ERR_MODIFIED);
        }
    }


    /* verify version number */

    vno = (*ptr++ & 0xff);
    vno = (vno<<8) | (*ptr++ & 0xff);

    if (vno != 1)
        return(KRB5KDC_ERR_BAD_PVNO);

    /* read, check ap-rep length */

    ap_rep.length = (*ptr++ & 0xff);
    ap_rep.length = (ap_rep.length<<8) | (*ptr++ & 0xff);

    if (ptr + ap_rep.length >= packet->data + packet->length)
        return(KRB5KRB_AP_ERR_MODIFIED);

    if (ap_rep.length) {
        /* verify ap_rep */
        ap_rep.data = ptr;
        ptr += ap_rep.length;

        /*
         * Save send_subkey to later smash recv_subkey.
         */
        ret = krb5_auth_con_getsendsubkey(context, auth_context, &tmp);
        if (ret)
            return ret;

        ret = krb5_rd_rep(context, auth_context, &ap_rep, &ap_rep_enc);
        if (ret) {
            krb5_free_keyblock(context, tmp);
            return(ret);
        }

        krb5_free_ap_rep_enc_part(context, ap_rep_enc);

        /* extract and decrypt the result */

        cipherresult.data = ptr;
        cipherresult.length = (packet->data + packet->length) - ptr;

        /*
         * Smash recv_subkey to be send_subkey, per spec.
         */
        ret = krb5_auth_con_setrecvsubkey(context, auth_context, tmp);
        krb5_free_keyblock(context, tmp);
        if (ret)
            return ret;

        ret = krb5_rd_priv(context, auth_context, &cipherresult, &clearresult,
                           &replay);

        if (ret)
            return(ret);
    } else {
        cipherresult.data = ptr;
        cipherresult.length = (packet->data + packet->length) - ptr;

        if ((ret = krb5_rd_error(context, &cipherresult, &krberror)))
            return(ret);

        clearresult = krberror->e_data;
    }

    if (clearresult.length < 2) {
        ret = KRB5KRB_AP_ERR_MODIFIED;
        goto cleanup;
    }

    ptr = clearresult.data;

    *result_code = (*ptr++ & 0xff);
    *result_code = (*result_code<<8) | (*ptr++ & 0xff);

    if ((*result_code < KRB5_KPASSWD_SUCCESS) ||
        (*result_code > KRB5_KPASSWD_INITIAL_FLAG_NEEDED)) {
        ret = KRB5KRB_AP_ERR_MODIFIED;
        goto cleanup;
    }

    /* all success replies should be authenticated/encrypted */

    if ((ap_rep.length == 0) && (*result_code == KRB5_KPASSWD_SUCCESS)) {
        ret = KRB5KRB_AP_ERR_MODIFIED;
        goto cleanup;
    }

    result_data->length = (clearresult.data + clearresult.length) - ptr;

    if (result_data->length) {
        result_data->data = (char *) malloc(result_data->length);
        if (result_data->data == NULL) {
            ret = ENOMEM;
            goto cleanup;
        }
        memcpy(result_data->data, ptr, result_data->length);
    } else {
        result_data->data = NULL;
    }

    ret = 0;

cleanup:
    if (ap_rep.length) {
        free(clearresult.data);
    } else {
        krb5_free_error(context, krberror);
    }

    return(ret);
}

krb5_error_code KRB5_CALLCONV
krb5_chpw_result_code_string(krb5_context context, int result_code,
                             char **code_string)
{
    switch (result_code) {
    case KRB5_KPASSWD_MALFORMED:
        *code_string = "Malformed request error";
        break;
    case KRB5_KPASSWD_HARDERROR:
        *code_string = "Server error";
        break;
    case KRB5_KPASSWD_AUTHERROR:
        *code_string = "Authentication error";
        break;
    case KRB5_KPASSWD_SOFTERROR:
        *code_string = "Password change rejected";
        break;
    default:
        *code_string = "Password change failed";
        break;
    }

    return(0);
}

krb5_error_code
krb5int_mk_setpw_req(krb5_context context,
                     krb5_auth_context auth_context,
                     krb5_data *ap_req,
                     krb5_principal targprinc,
                     char *passwd,
                     krb5_data *packet)
{
    krb5_error_code ret;
    krb5_data   cipherpw;
    krb5_data   *encoded_setpw;
    struct krb5_setpw_req req;

    char *ptr;

    cipherpw.data = NULL;
    cipherpw.length = 0;

    if ((ret = krb5_auth_con_setflags(context, auth_context,
                                      KRB5_AUTH_CONTEXT_DO_SEQUENCE)))
        return(ret);

    req.target = targprinc;
    req.password.data = passwd;
    req.password.length = strlen(passwd);
    ret = encode_krb5_setpw_req(&req, &encoded_setpw);
    if (ret) {
        return ret;
    }

    if ((ret = krb5_mk_priv(context, auth_context, encoded_setpw, &cipherpw, NULL)) != 0) {
        krb5_free_data(context, encoded_setpw);
        return(ret);
    }
    krb5_free_data(context, encoded_setpw);


    packet->length = 6 + ap_req->length + cipherpw.length;
    packet->data = (char *) malloc(packet->length);
    if (packet->data  == NULL) {
        ret = ENOMEM;
        goto cleanup;
    }
    ptr = packet->data;
    /*
    ** build the packet -
    */
    /* put in the length */
    store_16_be(packet->length, ptr);
    ptr += 2;
    /* put in the version */
    *ptr++ = (char)0xff;
    *ptr++ = (char)0x80;
    /* the ap_req length is big endian */
    store_16_be(ap_req->length, ptr);
    ptr += 2;
    /* put in the request data */
    memcpy(ptr, ap_req->data, ap_req->length);
    ptr += ap_req->length;
    /*
    ** put in the "private" password data -
    */
    memcpy(ptr, cipherpw.data, cipherpw.length);
    ret = 0;
cleanup:
    if (cipherpw.data)
        krb5_free_data_contents(context, &cipherpw);
    if ((ret != 0) && packet->data) {
        free(packet->data);
        packet->data = NULL;
    }
    return ret;
}

krb5_error_code
krb5int_rd_setpw_rep(krb5_context context, krb5_auth_context auth_context,
                     krb5_data *packet,
                     int *result_code, krb5_data *result_data)
{
    char *ptr;
    unsigned int message_length, version_number;
    krb5_data ap_rep;
    krb5_ap_rep_enc_part *ap_rep_enc;
    krb5_error_code ret;
    krb5_data cipherresult;
    krb5_data clearresult;
    krb5_keyblock *tmpkey;
    /*
    ** validate the packet length -
    */
    if (packet->length < 4)
        return(KRB5KRB_AP_ERR_MODIFIED);

    ptr = packet->data;

    /*
    ** see if it is an error
    */
    if (krb5_is_krb_error(packet)) {
        krb5_error *krberror;
        if ((ret = krb5_rd_error(context, packet, &krberror)))
            return(ret);
        if (krberror->e_data.data  == NULL) {
            ret = ERROR_TABLE_BASE_krb5 + (krb5_error_code) krberror->error;
            krb5_free_error(context, krberror);
            return (ret);
        }
        clearresult = krberror->e_data;
        krberror->e_data.data  = NULL; /*So we can free it later*/
        krberror->e_data.length = 0;
        krb5_free_error(context, krberror);
        ap_rep.length = 0;

    } else { /* Not an error*/

        /*
        ** validate the message length -
        ** length is big endian
        */
        message_length = (((ptr[0] << 8)&0xff) | (ptr[1]&0xff));
        ptr += 2;
        /*
        ** make sure the message length and packet length agree -
        */
        if (message_length != packet->length)
            return(KRB5KRB_AP_ERR_MODIFIED);
        /*
        ** get the version number -
        */
        version_number = (((ptr[0] << 8)&0xff) | (ptr[1]&0xff));
        ptr += 2;
        /*
        ** make sure we support the version returned -
        */
        /*
        ** set password version is 0xff80, change password version is 1
        */
        if (version_number != 1 && version_number != 0xff80)
            return(KRB5KDC_ERR_BAD_PVNO);
        /*
        ** now fill in ap_rep with the reply -
        */
        /*
        ** get the reply length -
        */
        ap_rep.length = (((ptr[0] << 8)&0xff) | (ptr[1]&0xff));
        ptr += 2;
        /*
        ** validate ap_rep length agrees with the packet length -
        */
        if (ptr + ap_rep.length >= packet->data + packet->length)
            return(KRB5KRB_AP_ERR_MODIFIED);
        /*
        ** if data was returned, set the ap_rep ptr -
        */
        if (ap_rep.length) {
            ap_rep.data = ptr;
            ptr += ap_rep.length;

            /*
             * Save send_subkey to later smash recv_subkey.
             */
            ret = krb5_auth_con_getsendsubkey(context, auth_context, &tmpkey);
            if (ret)
                return ret;

            ret = krb5_rd_rep(context, auth_context, &ap_rep, &ap_rep_enc);
            if (ret) {
                krb5_free_keyblock(context, tmpkey);
                return(ret);
            }

            krb5_free_ap_rep_enc_part(context, ap_rep_enc);
            /*
            ** now decrypt the result -
            */
            cipherresult.data = ptr;
            cipherresult.length = (packet->data + packet->length) - ptr;

            /*
             * Smash recv_subkey to be send_subkey, per spec.
             */
            ret = krb5_auth_con_setrecvsubkey(context, auth_context, tmpkey);
            krb5_free_keyblock(context, tmpkey);
            if (ret)
                return ret;

            ret = krb5_rd_priv(context, auth_context, &cipherresult, &clearresult,
                               NULL);
            if (ret)
                return(ret);
        } /*We got an ap_rep*/
        else
            return (KRB5KRB_AP_ERR_MODIFIED);
    } /*Response instead of error*/

    /*
    ** validate the cleartext length
    */
    if (clearresult.length < 2) {
        ret = KRB5KRB_AP_ERR_MODIFIED;
        goto cleanup;
    }
    /*
    ** now decode the result -
    */
    ptr = clearresult.data;

    *result_code = (((ptr[0] << 8)&0xff) | (ptr[1]&0xff));
    ptr += 2;

    /*
    ** result code 5 is access denied
    */
    if ((*result_code < KRB5_KPASSWD_SUCCESS) || (*result_code > 5)) {
        ret = KRB5KRB_AP_ERR_MODIFIED;
        goto cleanup;
    }
    /*
    ** all success replies should be authenticated/encrypted
    */
    if ((ap_rep.length == 0) && (*result_code == KRB5_KPASSWD_SUCCESS)) {
        ret = KRB5KRB_AP_ERR_MODIFIED;
        goto cleanup;
    }

    if (result_data) {
        result_data->length = (clearresult.data + clearresult.length) - ptr;

        if (result_data->length) {
            result_data->data = (char *) malloc(result_data->length);
            if (result_data->data)
                memcpy(result_data->data, ptr, result_data->length);
        } else
            result_data->data = NULL;
    }
    ret = 0;

cleanup:
    krb5_free_data_contents(context, &clearresult);
    return(ret);
}

krb5_error_code
krb5int_setpw_result_code_string(krb5_context context, int result_code,
                                 const char **code_string)
{
    switch (result_code) {
    case KRB5_KPASSWD_MALFORMED:
        *code_string = "Malformed request error";
        break;
    case KRB5_KPASSWD_HARDERROR:
        *code_string = "Server error";
        break;
    case KRB5_KPASSWD_AUTHERROR:
        *code_string = "Authentication error";
        break;
    case KRB5_KPASSWD_SOFTERROR:
        *code_string = "Password change rejected";
        break;
    case 5: /* access denied */
        *code_string = "Access denied";
        break;
    case 6:     /* bad version */
        *code_string = "Wrong protocol version";
        break;
    case 7: /* initial flag is needed */
        *code_string = "Initial password required";
        break;
    case 0:
        *code_string = "Success";
        break;
    default:
        *code_string = "Password change failed";
        break;
    }

    return(0);
}