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/*
* Copyright (c) 1997, 1998 Kungliga Tekniska Högskolan
* (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 "gssapi_locl.h"
RCSID("$Id: unwrap.c,v 1.10 1999/12/02 17:05:04 joda Exp $");
OM_uint32
gss_krb5_getsomekey(const gss_ctx_id_t context_handle,
des_cblock *key)
{
/* XXX this is ugly, and probably incorrect... */
krb5_keyblock *skey;
krb5_auth_con_getlocalsubkey(gssapi_krb5_context,
context_handle->auth_context,
&skey);
if(skey == NULL)
krb5_auth_con_getremotesubkey(gssapi_krb5_context,
context_handle->auth_context,
&skey);
if(skey == NULL)
krb5_auth_con_getkey(gssapi_krb5_context,
context_handle->auth_context,
&skey);
if(skey == NULL)
return GSS_S_FAILURE;
memcpy(key, skey->keyvalue.data, sizeof(*key));
krb5_free_keyblock(gssapi_krb5_context, skey);
return 0;
}
OM_uint32 gss_unwrap
(OM_uint32 * minor_status,
const gss_ctx_id_t context_handle,
const gss_buffer_t input_message_buffer,
gss_buffer_t output_message_buffer,
int * conf_state,
gss_qop_t * qop_state
)
{
u_char *p, *pad;
size_t len;
struct md5 md5;
u_char hash[16], seq_data[8];
des_key_schedule schedule;
des_cblock key;
des_cblock zero;
int i;
int32_t seq_number;
size_t padlength;
OM_uint32 ret;
int cstate;
p = input_message_buffer->value;
ret = gssapi_krb5_verify_header (&p,
input_message_buffer->length,
"\x02\x01");
if (ret)
return ret;
if (memcmp (p, "\x00\x00", 2) != 0)
return GSS_S_BAD_SIG;
p += 2;
if (memcmp (p, "\x00\x00", 2) == 0) {
cstate = 1;
} else if (memcmp (p, "\xFF\xFF", 2) == 0) {
cstate = 0;
} else
return GSS_S_BAD_MIC;
p += 2;
if(conf_state != NULL)
*conf_state = cstate;
if (memcmp (p, "\xff\xff", 2) != 0)
return GSS_S_DEFECTIVE_TOKEN;
p += 2;
p += 16;
len = p - (u_char *)input_message_buffer->value;
if(cstate) {
/* decrypt data */
gss_krb5_getsomekey(context_handle, &key);
for (i = 0; i < sizeof(key); ++i)
key[i] ^= 0xf0;
des_set_key (&key, schedule);
memset (&zero, 0, sizeof(zero));
des_cbc_encrypt ((des_cblock *)p,
(des_cblock *)p,
input_message_buffer->length - len,
schedule,
&zero,
DES_DECRYPT);
memset (key, 0, sizeof(key));
memset (schedule, 0, sizeof(schedule));
}
/* check pad */
pad = (u_char *)input_message_buffer->value + input_message_buffer->length - 1;
padlength = *pad;
for (i = padlength; i > 0 && *pad == padlength; i--, pad--)
;
if (i != 0)
return GSS_S_BAD_MIC;
md5_init (&md5);
md5_update (&md5, p - 24, 8);
md5_update (&md5, p, input_message_buffer->length - len);
md5_finito (&md5, hash);
memset (&zero, 0, sizeof(zero));
gss_krb5_getsomekey(context_handle, &key);
des_set_key (&key, schedule);
des_cbc_cksum ((des_cblock *)hash,
(des_cblock *)hash, sizeof(hash), schedule, &zero);
if (memcmp (p - 8, hash, 8) != 0)
return GSS_S_BAD_MIC;
/* verify sequence number */
krb5_auth_getremoteseqnumber (gssapi_krb5_context,
context_handle->auth_context,
&seq_number);
seq_data[0] = (seq_number >> 0) & 0xFF;
seq_data[1] = (seq_number >> 8) & 0xFF;
seq_data[2] = (seq_number >> 16) & 0xFF;
seq_data[3] = (seq_number >> 24) & 0xFF;
memset (seq_data + 4,
(context_handle->more_flags & LOCAL) ? 0xFF : 0,
4);
p -= 16;
des_set_key (&key, schedule);
des_cbc_encrypt ((des_cblock *)p, (des_cblock *)p, 8,
schedule, (des_cblock *)hash, DES_DECRYPT);
memset (key, 0, sizeof(key));
memset (schedule, 0, sizeof(schedule));
if (memcmp (p, seq_data, 8) != 0) {
return GSS_S_BAD_MIC;
}
krb5_auth_setremoteseqnumber (gssapi_krb5_context,
context_handle->auth_context,
++seq_number);
/* copy out data */
output_message_buffer->length = input_message_buffer->length
- len - 8 - padlength;
output_message_buffer->value = malloc(output_message_buffer->length);
if(output_message_buffer->length != 0 && output_message_buffer->value == NULL)
return GSS_S_FAILURE;
memcpy (output_message_buffer->value,
p + 24,
output_message_buffer->length);
return GSS_S_COMPLETE;
}
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