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/*
* Copyright (c) 2019-2020, AuriStor, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
* COPYRIGHT HOLDER 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 "sanon_locl.h"
OM_uint32 GSSAPI_CALLCONV
_gss_sanon_accept_sec_context(OM_uint32 *minor,
gss_ctx_id_t *context_handle,
gss_const_cred_id_t verifier_cred_handle,
const gss_buffer_t input_token,
const gss_channel_bindings_t input_chan_bindings,
gss_name_t *src_name,
gss_OID *mech_type,
gss_buffer_t output_token,
OM_uint32 *ret_flags,
OM_uint32 *time_rec,
gss_cred_id_t *delegated_cred_handle)
{
static gss_buffer_desc empty = GSS_C_EMPTY_BUFFER;
OM_uint32 major, tmp;
sanon_ctx sc = (sanon_ctx)*context_handle;
gss_buffer_desc mech_input_token = GSS_C_EMPTY_BUFFER;
gss_buffer_desc initiator_pk = GSS_C_EMPTY_BUFFER;
gss_buffer_desc hok_mic = GSS_C_EMPTY_BUFFER;
gss_buffer_desc session_key = GSS_C_EMPTY_BUFFER;
OM_uint32 req_flags = 0;
if (output_token == GSS_C_NO_BUFFER) {
*minor = EINVAL;
major = GSS_S_FAILURE;
goto out;
}
_mg_buffer_zero(output_token);
if (input_token == GSS_C_NO_BUFFER) {
major = GSS_S_DEFECTIVE_TOKEN;
goto out;
} else if (sc != NULL) {
major = GSS_S_BAD_STATUS;
goto out;
}
major = gss_decapsulate_token(input_token,
GSS_SANON_X25519_MECHANISM,
&mech_input_token);
if (major != GSS_S_COMPLETE)
goto out;
sc = calloc(1, sizeof(*sc));
if (sc == NULL) {
*minor = ENOMEM;
major = GSS_S_FAILURE;
goto out;
}
/* initiator token can include optional 64-bit flags */
if (mech_input_token.length != crypto_scalarmult_curve25519_BYTES &&
mech_input_token.length != crypto_scalarmult_curve25519_BYTES + 8) {
*minor = 0;
major = GSS_S_DEFECTIVE_TOKEN;
goto out;
}
initiator_pk = mech_input_token;
initiator_pk.length = crypto_scalarmult_curve25519_BYTES;
/* compute public and secret keys */
major = _gss_sanon_curve25519_base(minor, sc);
if (major != GSS_S_COMPLETE)
goto out;
if (mech_input_token.length > crypto_scalarmult_curve25519_BYTES) {
/* extra flags */
uint8_t *p = (uint8_t *)mech_input_token.value + crypto_scalarmult_curve25519_BYTES;
uint32_t dummy;
_gss_mg_decode_be_uint32(p, &dummy); /* upper 32 bits presently unused */
_gss_mg_decode_be_uint32(&p[4], &req_flags);
}
/* compute shared secret */
major = _gss_sanon_curve25519(minor, sc, &initiator_pk, req_flags,
input_chan_bindings, &session_key);
if (major != GSS_S_COMPLETE)
goto out;
/* do not let initiator set any other flags */
req_flags &= SANON_PROTOCOL_FLAG_MASK;
req_flags |= GSS_C_REPLAY_FLAG | GSS_C_SEQUENCE_FLAG | GSS_C_CONF_FLAG |
GSS_C_INTEG_FLAG | GSS_C_ANON_FLAG | GSS_C_TRANS_FLAG |
GSS_C_CHANNEL_BOUND_FLAG; /* CB part of KDF, so always validated */
major = _gss_sanon_import_rfc4121_context(minor, sc, req_flags, &session_key);
if (major != GSS_S_COMPLETE)
goto out;
major = _gss_sanon_get_mic(minor, (gss_const_ctx_id_t)sc,
GSS_C_QOP_DEFAULT, &empty, &hok_mic);
if (major != GSS_S_COMPLETE)
goto out;
output_token->length = sizeof(sc->pk) + hok_mic.length;
output_token->value = malloc(output_token->length);
if (output_token->value == NULL) {
output_token->length = 0;
*minor = ENOMEM;
major = GSS_S_FAILURE;
goto out;
}
memcpy(output_token->value, sc->pk, sizeof(sc->pk));
memcpy((uint8_t *)output_token->value + sizeof(sc->pk), hok_mic.value, hok_mic.length);
major = GSS_S_COMPLETE;
*context_handle = (gss_ctx_id_t)sc;
if (src_name)
*src_name = _gss_sanon_anonymous_identity;
if (ret_flags)
*ret_flags = req_flags;
if (time_rec)
*time_rec = GSS_C_INDEFINITE;
out:
if (mech_type)
*mech_type = GSS_SANON_X25519_MECHANISM;
if (delegated_cred_handle)
*delegated_cred_handle = GSS_C_NO_CREDENTIAL;
if (GSS_ERROR(major)) {
_gss_sanon_delete_sec_context(&tmp, (gss_ctx_id_t *)&sc, GSS_C_NO_BUFFER);
*context_handle = GSS_C_NO_CONTEXT;
}
gss_release_buffer(&tmp, &mech_input_token);
gss_release_buffer(&tmp, &hok_mic);
_gss_secure_release_buffer(&tmp, &session_key);
return major;
}
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