kerberos_pac.c

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/* 
   Unix SMB/CIFS implementation.

   Create and parse the krb5 PAC
   
   Copyright (C) Andrew Bartlett <[e-mail]> 2004-2005
   Copyright (C) Andrew Tridgell 2001
   Copyright (C) Luke Howard 2002-2003
   Copyright (C) Stefan Metzmacher 2004-2005

   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 "system/kerberos.h"
#include "auth/kerberos/kerberos.h"
#include "librpc/gen_ndr/ndr_krb5pac.h"
#include "lib/ldb/include/ldb.h"
#include "auth/auth_sam_reply.h"
#include "param/param.h"

static krb5_error_code check_pac_checksum(TALLOC_CTX *mem_ctx, 
					  DATA_BLOB pac_data,
					  struct PAC_SIGNATURE_DATA *sig,
					  krb5_context context,
					  const krb5_keyblock *keyblock)
{
	krb5_error_code ret;
	krb5_crypto crypto;
	Checksum cksum;

	cksum.cksumtype		= (CKSUMTYPE)sig->type;
	cksum.checksum.length	= sig->signature.length;
	cksum.checksum.data	= sig->signature.data;

	ret = krb5_crypto_init(context,
			       keyblock,
			       0,
			       &crypto);
	if (ret) {
		DEBUG(0,("krb5_crypto_init() failed: %s\n", 
			  smb_get_krb5_error_message(context, ret, mem_ctx)));
		return ret;
	}
	ret = krb5_verify_checksum(context,
				   crypto,
				   KRB5_KU_OTHER_CKSUM,
				   pac_data.data,
				   pac_data.length,
				   &cksum);
	krb5_crypto_destroy(context, crypto);

	return ret;
}

 NTSTATUS kerberos_decode_pac(TALLOC_CTX *mem_ctx,
			      struct smb_iconv_convenience *iconv_convenience,
			      struct PAC_DATA **pac_data_out,
			      DATA_BLOB blob,
			      krb5_context context,
			      const krb5_keyblock *krbtgt_keyblock,
			      const krb5_keyblock *service_keyblock,
			      krb5_const_principal client_principal,
			      time_t tgs_authtime,
			      krb5_error_code *k5ret)
{
	krb5_error_code ret;
	NTSTATUS status;
	enum ndr_err_code ndr_err;
	struct PAC_SIGNATURE_DATA *srv_sig_ptr = NULL;
	struct PAC_SIGNATURE_DATA *kdc_sig_ptr = NULL;
	struct PAC_SIGNATURE_DATA *srv_sig_wipe = NULL;
	struct PAC_SIGNATURE_DATA *kdc_sig_wipe = NULL;
	struct PAC_LOGON_INFO *logon_info = NULL;
	struct PAC_LOGON_NAME *logon_name = NULL;
	struct PAC_DATA *pac_data;
	struct PAC_DATA_RAW *pac_data_raw;

	DATA_BLOB *srv_sig_blob = NULL;
	DATA_BLOB *kdc_sig_blob = NULL;

	DATA_BLOB modified_pac_blob;
	NTTIME tgs_authtime_nttime;
	krb5_principal client_principal_pac;
	int i;

	krb5_clear_error_string(context);

	if (k5ret) {
		*k5ret = KRB5_PARSE_MALFORMED;
	}

	pac_data = talloc(mem_ctx, struct PAC_DATA);
	pac_data_raw = talloc(mem_ctx, struct PAC_DATA_RAW);
	kdc_sig_wipe = talloc(mem_ctx, struct PAC_SIGNATURE_DATA);
	srv_sig_wipe = talloc(mem_ctx, struct PAC_SIGNATURE_DATA);
	if (!pac_data_raw || !pac_data || !kdc_sig_wipe || !srv_sig_wipe) {
		if (k5ret) {
			*k5ret = ENOMEM;
		}
		return NT_STATUS_NO_MEMORY;
	}

	ndr_err = ndr_pull_struct_blob(&blob, pac_data, 
			iconv_convenience, pac_data,
		       (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		status = ndr_map_error2ntstatus(ndr_err);
		DEBUG(0,("can't parse the PAC: %s\n",
			nt_errstr(status)));
		return status;
	}

	if (pac_data->num_buffers < 4) {
		/* we need logon_ingo, service_key and kdc_key */
		DEBUG(0,("less than 4 PAC buffers\n"));
		return NT_STATUS_INVALID_PARAMETER;
	}

	ndr_err = ndr_pull_struct_blob(&blob, pac_data_raw, 
				       iconv_convenience, pac_data_raw,
				       (ndr_pull_flags_fn_t)ndr_pull_PAC_DATA_RAW);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		status = ndr_map_error2ntstatus(ndr_err);
		DEBUG(0,("can't parse the PAC: %s\n",
			nt_errstr(status)));
		return status;
	}

	if (pac_data_raw->num_buffers < 4) {
		/* we need logon_ingo, service_key and kdc_key */
		DEBUG(0,("less than 4 PAC buffers\n"));
		return NT_STATUS_INVALID_PARAMETER;
	}

	if (pac_data->num_buffers != pac_data_raw->num_buffers) {
		/* we need logon_ingo, service_key and kdc_key */
		DEBUG(0,("misparse!  PAC_DATA has %d buffers while PAC_DATA_RAW has %d\n",
			 pac_data->num_buffers, pac_data_raw->num_buffers));
		return NT_STATUS_INVALID_PARAMETER;
	}

	for (i=0; i < pac_data->num_buffers; i++) {
		if (pac_data->buffers[i].type != pac_data_raw->buffers[i].type) {
			DEBUG(0,("misparse!  PAC_DATA buffer %d has type %d while PAC_DATA_RAW has %d\n",
				 i, pac_data->buffers[i].type, pac_data->buffers[i].type));
			return NT_STATUS_INVALID_PARAMETER;
		}
		switch (pac_data->buffers[i].type) {
			case PAC_TYPE_LOGON_INFO:
				if (!pac_data->buffers[i].info) {
					break;
				}
				logon_info = pac_data->buffers[i].info->logon_info.info;
				break;
			case PAC_TYPE_SRV_CHECKSUM:
				if (!pac_data->buffers[i].info) {
					break;
				}
				srv_sig_ptr = &pac_data->buffers[i].info->srv_cksum;
				srv_sig_blob = &pac_data_raw->buffers[i].info->remaining;
				break;
			case PAC_TYPE_KDC_CHECKSUM:
				if (!pac_data->buffers[i].info) {
					break;
				}
				kdc_sig_ptr = &pac_data->buffers[i].info->kdc_cksum;
				kdc_sig_blob = &pac_data_raw->buffers[i].info->remaining;
				break;
			case PAC_TYPE_LOGON_NAME:
				logon_name = &pac_data->buffers[i].info->logon_name;
				break;
			default:
				break;
		}
	}

	if (!logon_info) {
		DEBUG(0,("PAC no logon_info\n"));
		return NT_STATUS_INVALID_PARAMETER;
	}

	if (!logon_name) {
		DEBUG(0,("PAC no logon_name\n"));
		return NT_STATUS_INVALID_PARAMETER;
	}

	if (!srv_sig_ptr || !srv_sig_blob) {
		DEBUG(0,("PAC no srv_key\n"));
		return NT_STATUS_INVALID_PARAMETER;
	}

	if (!kdc_sig_ptr || !kdc_sig_blob) {
		DEBUG(0,("PAC no kdc_key\n"));
		return NT_STATUS_INVALID_PARAMETER;
	}

	/* Find and zero out the signatures, as required by the signing algorithm */

	/* We find the data blobs above, now we parse them to get at the exact portion we should zero */
	ndr_err = ndr_pull_struct_blob(kdc_sig_blob, kdc_sig_wipe, 
				       iconv_convenience, kdc_sig_wipe,
				       (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		status = ndr_map_error2ntstatus(ndr_err);
		DEBUG(0,("can't parse the KDC signature: %s\n",
			nt_errstr(status)));
		return status;
	}
	
	ndr_err = ndr_pull_struct_blob(srv_sig_blob, srv_sig_wipe, 
				       iconv_convenience, srv_sig_wipe,
				       (ndr_pull_flags_fn_t)ndr_pull_PAC_SIGNATURE_DATA);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		status = ndr_map_error2ntstatus(ndr_err);
		DEBUG(0,("can't parse the SRV signature: %s\n",
			nt_errstr(status)));
		return status;
	}

	/* Now zero the decoded structure */
	memset(kdc_sig_wipe->signature.data, '\0', kdc_sig_wipe->signature.length);
	memset(srv_sig_wipe->signature.data, '\0', srv_sig_wipe->signature.length);
	
	/* and reencode, back into the same place it came from */
	ndr_err = ndr_push_struct_blob(kdc_sig_blob, pac_data_raw, 
				       iconv_convenience,
				       kdc_sig_wipe,
				       (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		status = ndr_map_error2ntstatus(ndr_err);
		DEBUG(0,("can't repack the KDC signature: %s\n",
			nt_errstr(status)));
		return status;
	}
	ndr_err = ndr_push_struct_blob(srv_sig_blob, pac_data_raw, 
				       iconv_convenience,
				       srv_sig_wipe,
				       (ndr_push_flags_fn_t)ndr_push_PAC_SIGNATURE_DATA);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		status = ndr_map_error2ntstatus(ndr_err);
		DEBUG(0,("can't repack the SRV signature: %s\n",
			nt_errstr(status)));
		return status;
	}

	/* push out the whole structure, but now with zero'ed signatures */
	ndr_err = ndr_push_struct_blob(&modified_pac_blob, pac_data_raw, 
				       iconv_convenience,
				       pac_data_raw,
				       (ndr_push_flags_fn_t)ndr_push_PAC_DATA_RAW);
	if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
		status = ndr_map_error2ntstatus(ndr_err);
		DEBUG(0,("can't repack the RAW PAC: %s\n",
			nt_errstr(status)));
		return status;
	}

	/* verify by service_key */
	ret = check_pac_checksum(mem_ctx, 
				 modified_pac_blob, srv_sig_ptr, 
				 context, 
				 service_keyblock);
	if (ret) {
		DEBUG(1, ("PAC Decode: Failed to verify the service signature: %s\n",
			  smb_get_krb5_error_message(context, ret, mem_ctx)));
		if (k5ret) {
			*k5ret = ret;
		}
		return NT_STATUS_ACCESS_DENIED;
	}

	if (krbtgt_keyblock) {
		ret = check_pac_checksum(mem_ctx, 
					    srv_sig_ptr->signature, kdc_sig_ptr, 
					    context, krbtgt_keyblock);
		if (ret) {
			DEBUG(1, ("PAC Decode: Failed to verify the KDC signature: %s\n",
				  smb_get_krb5_error_message(context, ret, mem_ctx)));
			if (k5ret) {
				*k5ret = ret;
			}
			return NT_STATUS_ACCESS_DENIED;
		}
	}

	/* Convert to NT time, so as not to loose accuracy in comparison */
	unix_to_nt_time(&tgs_authtime_nttime, tgs_authtime);

	if (tgs_authtime_nttime != logon_name->logon_time) {
		DEBUG(2, ("PAC Decode: Logon time mismatch between ticket and PAC!\n"));
		DEBUG(2, ("PAC Decode: PAC: %s\n", nt_time_string(mem_ctx, logon_name->logon_time)));
		DEBUG(2, ("PAC Decode: Ticket: %s\n", nt_time_string(mem_ctx, tgs_authtime_nttime)));
		return NT_STATUS_ACCESS_DENIED;
	}

	ret = krb5_parse_name_flags(context, logon_name->account_name, KRB5_PRINCIPAL_PARSE_NO_REALM, 
				    &client_principal_pac);
	if (ret) {
		DEBUG(2, ("Could not parse name from incoming PAC: [%s]: %s\n", 
			  logon_name->account_name, 
			  smb_get_krb5_error_message(context, ret, mem_ctx)));
		if (k5ret) {
			*k5ret = ret;
		}
		return NT_STATUS_INVALID_PARAMETER;
	}

	if (!krb5_principal_compare_any_realm(context, client_principal, client_principal_pac)) {
		DEBUG(2, ("Name in PAC [%s] does not match principal name in ticket\n", 
			  logon_name->account_name));
		return NT_STATUS_ACCESS_DENIED;
	}
	
#if 0
	if (strcasecmp(logon_info->info3.base.account_name.string, 
		       "Administrator")== 0) {