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/*
Unix SMB/CIFS mplementation.
Helper functions for applying replicated objects
Copyright (C) Stefan Metzmacher <metze@samba.org> 2007
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "includes.h"
#include "../lib/util/dlinklist.h"
#include "librpc/gen_ndr/ndr_misc.h"
#include "librpc/gen_ndr/ndr_drsuapi.h"
#include "librpc/gen_ndr/ndr_drsblobs.h"
#include "../lib/crypto/crypto.h"
#include "../libcli/drsuapi/drsuapi.h"
#include "libcli/auth/libcli_auth.h"
WERROR drsuapi_decrypt_attribute_value(TALLOC_CTX *mem_ctx,
const DATA_BLOB *gensec_skey,
bool rid_crypt,
uint32_t rid,
DATA_BLOB *in,
DATA_BLOB *out)
{
DATA_BLOB confounder;
DATA_BLOB enc_buffer;
struct MD5Context md5;
uint8_t _enc_key[16];
DATA_BLOB enc_key;
DATA_BLOB dec_buffer;
uint32_t crc32_given;
uint32_t crc32_calc;
DATA_BLOB checked_buffer;
DATA_BLOB plain_buffer;
/*
* users with rid == 0 should not exist
*/
if (rid_crypt && rid == 0) {
return WERR_DS_DRA_INVALID_PARAMETER;
}
/*
* the first 16 bytes at the beginning are the confounder
* followed by the 4 byte crc32 checksum
*/
if (in->length < 20) {
return WERR_DS_DRA_INVALID_PARAMETER;
}
confounder = data_blob_const(in->data, 16);
enc_buffer = data_blob_const(in->data + 16, in->length - 16);
/*
* build the encryption key md5 over the session key followed
* by the confounder
*
* here the gensec session key is used and
* not the dcerpc ncacn_ip_tcp "SystemLibraryDTC" key!
*/
enc_key = data_blob_const(_enc_key, sizeof(_enc_key));
MD5Init(&md5);
MD5Update(&md5, gensec_skey->data, gensec_skey->length);
MD5Update(&md5, confounder.data, confounder.length);
MD5Final(enc_key.data, &md5);
/*
* copy the encrypted buffer part and
* decrypt it using the created encryption key using arcfour
*/
dec_buffer = data_blob_const(enc_buffer.data, enc_buffer.length);
arcfour_crypt_blob(dec_buffer.data, dec_buffer.length, &enc_key);
/*
* the first 4 byte are the crc32 checksum
* of the remaining bytes
*/
crc32_given = IVAL(dec_buffer.data, 0);
crc32_calc = crc32_calc_buffer(dec_buffer.data + 4 , dec_buffer.length - 4);
if (crc32_given != crc32_calc) {
return WERR_SEC_E_DECRYPT_FAILURE;
}
checked_buffer = data_blob_const(dec_buffer.data + 4, dec_buffer.length - 4);
plain_buffer = data_blob_talloc(mem_ctx, checked_buffer.data, checked_buffer.length);
W_ERROR_HAVE_NO_MEMORY(plain_buffer.data);
/*
* The following rid_crypt obfuscation isn't session specific
* and not really needed here, because we allways know the rid of the
* user account.
*
* some attributes with this 'additional encryption' include
* dBCSPwd, unicodePwd, ntPwdHistory, lmPwdHistory
*
* But for the rest of samba it's easier when we remove this static
* obfuscation here
*/
if (rid_crypt) {
uint32_t i, num_hashes;
if ((checked_buffer.length % 16) != 0) {
return WERR_DS_DRA_INVALID_PARAMETER;
}
num_hashes = plain_buffer.length / 16;
for (i = 0; i < num_hashes; i++) {
uint32_t offset = i * 16;
sam_rid_crypt(rid, checked_buffer.data + offset, plain_buffer.data + offset, 0);
}
}
*out = plain_buffer;
return WERR_OK;
}
WERROR drsuapi_decrypt_attribute(TALLOC_CTX *mem_ctx,
const DATA_BLOB *gensec_skey,
uint32_t rid,
struct drsuapi_DsReplicaAttribute *attr)
{
WERROR status;
DATA_BLOB *enc_data;
DATA_BLOB plain_data;
bool rid_crypt = false;
if (attr->value_ctr.num_values == 0) {
return WERR_OK;
}
switch (attr->attid) {
case DRSUAPI_ATTRIBUTE_dBCSPwd:
case DRSUAPI_ATTRIBUTE_unicodePwd:
case DRSUAPI_ATTRIBUTE_ntPwdHistory:
case DRSUAPI_ATTRIBUTE_lmPwdHistory:
rid_crypt = true;
break;
case DRSUAPI_ATTRIBUTE_supplementalCredentials:
case DRSUAPI_ATTRIBUTE_priorValue:
case DRSUAPI_ATTRIBUTE_currentValue:
case DRSUAPI_ATTRIBUTE_trustAuthOutgoing:
case DRSUAPI_ATTRIBUTE_trustAuthIncoming:
case DRSUAPI_ATTRIBUTE_initialAuthOutgoing:
case DRSUAPI_ATTRIBUTE_initialAuthIncoming:
break;
default:
return WERR_OK;
}
if (attr->value_ctr.num_values > 1) {
return WERR_DS_DRA_INVALID_PARAMETER;
}
if (!attr->value_ctr.values[0].blob) {
return WERR_DS_DRA_INVALID_PARAMETER;
}
enc_data = attr->value_ctr.values[0].blob;
status = drsuapi_decrypt_attribute_value(mem_ctx,
gensec_skey,
rid_crypt,
rid,
enc_data,
&plain_data);
W_ERROR_NOT_OK_RETURN(status);
talloc_free(attr->value_ctr.values[0].blob->data);
*attr->value_ctr.values[0].blob = plain_data;
return WERR_OK;
}
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