changepw.c

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/*
 * Copyright (c) 1997 - 2005 Kungliga Tekniska H鰃skolan
 * (Royal Institute of Technology, Stockholm, Sweden). 
 * All rights reserved. 
 *
 * Redistribution and use in source and binary forms, with or without 
 * modification, are permitted provided that the following conditions 
 * are met: 
 *
 * 1. Redistributions of source code must retain the above copyright 
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. Redistributions in binary form must reproduce the above copyright 
 *    notice, this list of conditions and the following disclaimer in the 
 *    documentation and/or other materials provided with the distribution. 
 *
 * 3. Neither the name of the Institute nor the names of its contributors 
 *    may be used to endorse or promote products derived from this software 
 *    without specific prior written permission. 
 *
 * THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND 
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE 
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
 * SUCH DAMAGE. 
 */

#include <krb5_locl.h>

RCSID("$Id: changepw.c 21505 2007-07-12 12:28:38Z lha $");

static void
str2data (krb5_data *d,
	  const char *fmt,
	  ...) __attribute__ ((format (printf, 2, 3)));

static void
str2data (krb5_data *d,
	  const char *fmt,
	  ...)
{
    va_list args;
    char *str;

    va_start(args, fmt);
    d->length = vasprintf (&str, fmt, args);
    va_end(args);
    d->data = str;
}

/*
 * Change password protocol defined by
 * draft-ietf-cat-kerb-chg-password-02.txt
 * 
 * Share the response part of the protocol with MS set password
 * (RFC3244)
 */

static krb5_error_code
chgpw_send_request (krb5_context context,
		    krb5_auth_context *auth_context,
		    krb5_creds *creds,
		    krb5_principal targprinc,
		    int is_stream,
		    int sock,
		    const char *passwd,
		    const char *host)
{
    krb5_error_code ret;
    krb5_data ap_req_data;
    krb5_data krb_priv_data;
    krb5_data passwd_data;
    size_t len;
    u_char header[6];
    u_char *p;
    struct iovec iov[3];
    struct msghdr msghdr;

    if (is_stream)
	return KRB5_KPASSWD_MALFORMED;

    if (targprinc &&
	krb5_principal_compare(context, creds->client, targprinc) != TRUE)
	return KRB5_KPASSWD_MALFORMED;

    krb5_data_zero (&ap_req_data);

    ret = krb5_mk_req_extended (context,
				auth_context,
				AP_OPTS_MUTUAL_REQUIRED | AP_OPTS_USE_SUBKEY,
				NULL, /* in_data */
				creds,
				&ap_req_data);
    if (ret)
	return ret;

    passwd_data.data   = rk_UNCONST(passwd);
    passwd_data.length = strlen(passwd);

    krb5_data_zero (&krb_priv_data);

    ret = krb5_mk_priv (context,
			*auth_context,
			&passwd_data,
			&krb_priv_data,
			NULL);
    if (ret)
	goto out2;

    len = 6 + ap_req_data.length + krb_priv_data.length;
    p = header;
    *p++ = (len >> 8) & 0xFF;
    *p++ = (len >> 0) & 0xFF;
    *p++ = 0;
    *p++ = 1;
    *p++ = (ap_req_data.length >> 8) & 0xFF;
    *p++ = (ap_req_data.length >> 0) & 0xFF;

    memset(&msghdr, 0, sizeof(msghdr));
    msghdr.msg_name       = NULL;
    msghdr.msg_namelen    = 0;
    msghdr.msg_iov        = iov;
    msghdr.msg_iovlen     = sizeof(iov)/sizeof(*iov);
#if 0
    msghdr.msg_control    = NULL;
    msghdr.msg_controllen = 0;
#endif

    iov[0].iov_base    = (void*)header;
    iov[0].iov_len     = 6;
    iov[1].iov_base    = ap_req_data.data;
    iov[1].iov_len     = ap_req_data.length;
    iov[2].iov_base    = krb_priv_data.data;
    iov[2].iov_len     = krb_priv_data.length;

    if (sendmsg (sock, &msghdr, 0) < 0) {
	ret = errno;
	krb5_set_error_string(context, "sendmsg %s: %s", host, strerror(ret));
    }

    krb5_data_free (&krb_priv_data);
out2:
    krb5_data_free (&ap_req_data);
    return ret;
}

/*
 * Set password protocol as defined by RFC3244 --
 * Microsoft Windows 2000 Kerberos Change Password and Set Password Protocols
 */

static krb5_error_code
setpw_send_request (krb5_context context,
		    krb5_auth_context *auth_context,
		    krb5_creds *creds,
		    krb5_principal targprinc,
		    int is_stream,
		    int sock,
		    const char *passwd,
		    const char *host)
{
    krb5_error_code ret;
    krb5_data ap_req_data;
    krb5_data krb_priv_data;
    krb5_data pwd_data;
    ChangePasswdDataMS chpw;
    size_t len;
    u_char header[4 + 6];
    u_char *p;
    struct iovec iov[3];
    struct msghdr msghdr;

    krb5_data_zero (&ap_req_data);

    ret = krb5_mk_req_extended (context,
				auth_context,
				AP_OPTS_MUTUAL_REQUIRED | AP_OPTS_USE_SUBKEY,
				NULL, /* in_data */
				creds,
				&ap_req_data);
    if (ret)
	return ret;

    chpw.newpasswd.length = strlen(passwd);
    chpw.newpasswd.data = rk_UNCONST(passwd);
    if (targprinc) {
	chpw.targname = &targprinc->name;
	chpw.targrealm = &targprinc->realm;
    } else {
	chpw.targname = NULL;
	chpw.targrealm = NULL;
    }
	
    ASN1_MALLOC_ENCODE(ChangePasswdDataMS, pwd_data.data, pwd_data.length,
		       &chpw, &len, ret);
    if (ret) {
	krb5_data_free (&ap_req_data);
	return ret;
    }

    if(pwd_data.length != len)
	krb5_abortx(context, "internal error in ASN.1 encoder");

    ret = krb5_mk_priv (context,
			*auth_context,
			&pwd_data,
			&krb_priv_data,
			NULL);
    if (ret)
	goto out2;

    len = 6 + ap_req_data.length + krb_priv_data.length;
    p = header;
    if (is_stream) {
	_krb5_put_int(p, len, 4);
	p += 4;
    }
    *p++ = (len >> 8) & 0xFF;
    *p++ = (len >> 0) & 0xFF;
    *p++ = 0xff;
    *p++ = 0x80;
    *p++ = (ap_req_data.length >> 8) & 0xFF;
    *p++ = (ap_req_data.length >> 0) & 0xFF;

    memset(&msghdr, 0, sizeof(msghdr));
    msghdr.msg_name       = NULL;
    msghdr.msg_namelen    = 0;
    msghdr.msg_iov        = iov;
    msghdr.msg_iovlen     = sizeof(iov)/sizeof(*iov);
#if 0
    msghdr.msg_control    = NULL;
    msghdr.msg_controllen = 0;
#endif

    iov[0].iov_base    = (void*)header;
    if (is_stream)
	iov[0].iov_len     = 10;
    else
	iov[0].iov_len     = 6;
    iov[1].iov_base    = ap_req_data.data;
    iov[1].iov_len     = ap_req_data.length;
    iov[2].iov_base    = krb_priv_data.data;
    iov[2].iov_len     = krb_priv_data.length;

    if (sendmsg (sock, &msghdr, 0) < 0) {
	ret = errno;
	krb5_set_error_string(context, "sendmsg %s: %s", host, strerror(ret));
    }

    krb5_data_free (&krb_priv_data);
out2:
    krb5_data_free (&ap_req_data);
    krb5_data_free (&pwd_data);
    return ret;
}

static krb5_error_code
process_reply (krb5_context context,
	       krb5_auth_context auth_context,
	       int is_stream,
	       int sock,
	       int *result_code,
	       krb5_data *result_code_string,
	       krb5_data *result_string,
	       const char *host)
{
    krb5_error_code ret;
    u_char reply[1024 * 3];
    ssize_t len;
    uint16_t pkt_len, pkt_ver;
    krb5_data ap_rep_data;
    int save_errno;

    len = 0;
    if (is_stream) {
	while (len < sizeof(reply)) {
	    unsigned long size;

	    ret = recvfrom (sock, reply + len, sizeof(reply) - len, 
			    0, NULL, NULL);
	    if (ret < 0) {
		save_errno = errno;
		krb5_set_error_string(context, "recvfrom %s: %s",
				      host, strerror(save_errno));
		return save_errno;
	    } else if (ret == 0) {
		krb5_set_error_string(context, "recvfrom timeout %s", host);
		return 1;
	    }
	    len += ret;
	    if (len < 4)
		continue;
	    _krb5_get_int(reply, &size, 4);
	    if (size + 4 < len)
		continue;
	    memmove(reply, reply + 4, size);		
	    len = size;
	    break;
	}
	if (len == sizeof(reply)) {
	    krb5_set_error_string(context, "message too large from %s",
				  host);
	    return ENOMEM;
	}
    } else {
	ret = recvfrom (sock, reply, sizeof(reply), 0, NULL, NULL);
	if (ret < 0) {
	    save_errno = errno;
	    krb5_set_error_string(context, "recvfrom %s: %s",
				  host, strerror(save_errno));
	    return save_errno;
	}
	len = ret;
    }

    if (len < 6) {
	str2data (result_string, "server %s sent to too short message "
		  "(%ld bytes)", host, (long)len);
	*result_code = KRB5_KPASSWD_MALFORMED;
	return 0;
    }

    pkt_len = (reply[0] << 8) | (reply[1]);
    pkt_ver = (reply[2] << 8) | (reply[3]);

    if ((pkt_len != len) || (reply[1] == 0x7e || reply[1] == 0x5e)) {
	KRB_ERROR error;
	size_t size;
	u_char *p;

	memset(&error, 0, sizeof(error));

	ret = decode_KRB_ERROR(reply, len, &error, &size);
	if (ret)
	    return ret;

	if (error.e_data->length < 2) {
	    str2data(result_string, "server %s sent too short "
		     "e_data to print anything usable", host);
	    free_KRB_ERROR(&error);
	    *result_code = KRB5_KPASSWD_MALFORMED;
	    return 0;
	}

	p = error.e_data->data;
	*result_code = (p[0] << 8) | p[1];
	if (error.e_data->length == 2)
	    str2data(result_string, "server only sent error code");
	else 
	    krb5_data_copy (result_string,
			    p + 2,
			    error.e_data->length - 2);
	free_KRB_ERROR(&error);
	return 0;
    }

    if (pkt_len != len) {
	str2data (result_string, "client: wrong len in reply");
	*result_code = KRB5_KPASSWD_MALFORMED;
	return 0;
    }
    if (pkt_ver != KRB5_KPASSWD_VERS_CHANGEPW) {
	str2data (result_string,
		  "client: wrong version number (%d)", pkt_ver);
	*result_code = KRB5_KPASSWD_MALFORMED;
	return 0;
    }

    ap_rep_data.data = reply + 6;
    ap_rep_data.length  = (reply[4] << 8) | (reply[5]);
  
    if (reply + len < (u_char *)ap_rep_data.data + ap_rep_data.length) {
	str2data (result_string, "client: wrong AP len in reply");
	*result_code = KRB5_KPASSWD_MALFORMED;
	return 0;
    }

    if (ap_rep_data.length) {
	krb5_ap_rep_enc_part *ap_rep;
	krb5_data priv_data;
	u_char *p;

	priv_data.data   = (u_char*)ap_rep_data.data + ap_rep_data.length;
	priv_data.length = len - ap_rep_data.length - 6;

	ret = krb5_rd_rep (context,
			   auth_context,
			   &ap_rep_data,
			   &ap_rep);
	if (ret)
	    return ret;

	krb5_free_ap_rep_enc_part (context, ap_rep);

	ret = krb5_rd_priv (context,
			    auth_context,
			    &priv_data,
			    result_code_string,
			    NULL);
	if (ret) {
	    krb5_data_free (result_code_string);
	    return ret;
	}

	if (result_code_string->length < 2) {
	    *result_code = KRB5_KPASSWD_MALFORMED;