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/*
* Copyright 1993 by OpenVision Technologies, Inc.
*
* Permission to use, copy, modify, distribute, and sell this software
* and its documentation for any purpose is hereby granted without fee,
* provided that the above copyright notice appears in all copies and
* that both that copyright notice and this permission notice appear in
* supporting documentation, and that the name of OpenVision not be used
* in advertising or publicity pertaining to distribution of the software
* without specific, written prior permission. OpenVision makes no
* representations about the suitability of this software for any
* purpose. It is provided "as is" without express or implied warranty.
*
* OPENVISION DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
* EVENT SHALL OPENVISION BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
* USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
* OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#include "gssapiP_krb5.h"
#include <memory.h>
#include <krb5/rsa-md5.h>
/* message_buffer is an input if SIGN, output if SEAL, and ignored if DEL_CTX
conf_state is only valid if SEAL.
*/
OM_uint32 INTERFACE
kg_unseal(minor_status, context_handle, input_token_buffer, message_buffer,
conf_state, qop_state, toktype)
OM_uint32 *minor_status;
gss_ctx_id_t context_handle;
gss_buffer_t input_token_buffer;
gss_buffer_t message_buffer;
int *conf_state;
int *qop_state;
int toktype;
{
krb5_gss_ctx_id_rec *ctx;
krb5_error_code code;
int bodysize;
int tmsglen;
int signalg;
int sealalg;
gss_buffer_desc token;
unsigned char *ptr;
krb5_checksum desmac;
MD5_CTX md5;
unsigned char *cksum;
krb5_timestamp now;
unsigned char *plain;
int plainlen;
if (toktype == KG_TOK_SEAL_MSG) {
message_buffer->length = 0;
message_buffer->value = NULL;
}
/* validate the context handle */
if (! kg_validate_ctx_id(context_handle)) {
*minor_status = (OM_uint32) G_VALIDATE_FAILED;
return(GSS_S_NO_CONTEXT);
}
ctx = (krb5_gss_ctx_id_rec *) context_handle;
if (! ctx->established) {
*minor_status = KG_CTX_INCOMPLETE;
return(GSS_S_NO_CONTEXT);
}
/* parse the token, leave the data in message_buffer, setting conf_state */
/* verify the header */
ptr = (unsigned char *) input_token_buffer->value;
if (! g_verify_token_header(gss_mech_krb5, &bodysize,
&ptr, toktype, input_token_buffer->length)) {
*minor_status = 0;
return(GSS_S_DEFECTIVE_TOKEN);
}
if (toktype == KG_TOK_SEAL_MSG)
tmsglen = bodysize-22;
/* get the sign and seal algorithms */
signalg = ptr[0] + (ptr[1]<<8);
sealalg = ptr[2] + (ptr[3]<<8);
if (((signalg != 0) && (signalg != 1)) ||
((toktype != KG_TOK_SEAL_MSG) && (sealalg != 0xffff)) ||
((toktype == KG_TOK_SEAL_MSG) &&
((sealalg != 0xffff) && (sealalg != 0))) ||
(ptr[4] != 0xff) ||
(ptr[5] != 0xff)) {
*minor_status = 0;
return(GSS_S_DEFECTIVE_TOKEN);
}
/* get the token parameters */
/* decode the message, if SEAL */
if (toktype == KG_TOK_SEAL_MSG) {
if (sealalg == 0) {
if ((plain = (unsigned char *) xmalloc(tmsglen)) == NULL) {
*minor_status = ENOMEM;
return(GSS_S_FAILURE);
}
if (code = kg_decrypt(&ctx->enc, NULL, ptr+22, plain, tmsglen)) {
xfree(plain);
*minor_status = code;
return(GSS_S_FAILURE);
}
} else {
plain = ptr+22;
}
plainlen = tmsglen;
if (sealalg && ctx->big_endian)
token.length = tmsglen;
else
token.length = tmsglen - 8 - plain[tmsglen-1];
if (token.length) {
if ((token.value = xmalloc(token.length)) == NULL) {
if (sealalg == 0)
xfree(plain);
*minor_status = ENOMEM;
return(GSS_S_FAILURE);
}
if (sealalg && ctx->big_endian)
memcpy(token.value, plain, token.length);
else
memcpy(token.value, plain+8, token.length);
}
} else if (toktype == KG_TOK_SIGN_MSG) {
token = *message_buffer;
plain = token.value;
plainlen = token.length;
} else {
token.length = 0;
token.value = NULL;
plain = token.value;
plainlen = token.length;
}
/* compute the checksum of the message */
if (signalg == 0) {
/* compute the checksum of the message */
MD5Init(&md5);
MD5Update(&md5, (unsigned char *) ptr-2, 8);
if (ctx->big_endian)
MD5Update(&md5, token.value, token.length);
else
MD5Update(&md5, plain, plainlen);
MD5Final(&md5);
if (sealalg == 0)
xfree(plain);
/* XXX this depends on the key being a single-des key, but that's
all that kerberos supports right now */
if (code = krb5_calculate_checksum(context, CKSUMTYPE_DESCBC, md5.digest,
16, ctx->seq.key->contents,
ctx->seq.key->length,
&desmac)) {
if (toktype == KG_TOK_SEAL_MSG)
xfree(token.value);
*minor_status = code;
return(GSS_S_FAILURE);
}
cksum = desmac.contents;
} else {
if (! ctx->seed_init) {
if (code = kg_make_seed(ctx->subkey, ctx->seed)) {
if (sealalg == 0)
xfree(plain);
if (toktype == KG_TOK_SEAL_MSG)
xfree(token.value);
*minor_status = code;
return(GSS_S_FAILURE);
}
ctx->seed_init = 1;
}
MD5Init(&md5);
MD5Update(&md5, ctx->seed, sizeof(ctx->seed));
MD5Update(&md5, (unsigned char *) ptr-2, 8);
if (ctx->big_endian)
MD5Update(&md5, token.value, token.length);
else
MD5Update(&md5, plain, plainlen);
MD5Final(&md5);
if (sealalg == 0)
xfree(plain);
cksum = md5.digest;
}
/* compare the computed checksum against the transmitted checksum */
if (memcmp(cksum, ptr+14, 8) != 0) {
if (signalg == 0)
xfree(desmac.contents);
if (toktype == KG_TOK_SEAL_MSG)
xfree(token.value);
*minor_status = 0;
return(GSS_S_BAD_SIG);
}
if (signalg == 0)
xfree(desmac.contents);
/* XXX this is where the seq_num check would go */
/* it got through unscathed. Make sure the context is unexpired */
if (toktype == KG_TOK_SEAL_MSG)
*message_buffer = token;
if (conf_state)
*conf_state = (sealalg == 0);
if (qop_state)
*qop_state = GSS_C_QOP_DEFAULT;
if (code = krb5_timeofday(ctx->context, &now)) {
*minor_status = code;
return(GSS_S_FAILURE);
}
if (now > ctx->endtime) {
*minor_status = 0;
return(GSS_S_CONTEXT_EXPIRED);
}
/* success */
*minor_status = 0;
return(GSS_S_COMPLETE);
}
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