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/*
Unix SMB/CIFS implementation.
Copyright (C) Andrew Tridgell 2004
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 "smb_server/smb_server.h"
#include "libcli/raw/libcliraw.h"
#include "libcli/raw/raw_proto.h"
#include "param/param.h"
/*
sign an outgoing packet
*/
void smbsrv_sign_packet(struct smbsrv_request *req)
{
#if 0
/* enable this when packet signing is preventing you working out why valgrind
says that data is uninitialised */
file_save("pkt.dat", req->out.buffer, req->out.size);
#endif
switch (req->smb_conn->signing.signing_state) {
case SMB_SIGNING_ENGINE_OFF:
break;
case SMB_SIGNING_ENGINE_BSRSPYL:
/* mark the packet as signed - BEFORE we sign it...*/
mark_packet_signed(&req->out);
/* I wonder what BSRSPYL stands for - but this is what MS
actually sends! */
memcpy((req->out.hdr + HDR_SS_FIELD), "BSRSPYL ", 8);
break;
case SMB_SIGNING_ENGINE_ON:
sign_outgoing_message(&req->out,
&req->smb_conn->signing.mac_key,
req->seq_num+1);
break;
}
return;
}
/*
setup the signing key for a connection. Called after authentication succeeds
in a session setup
*/
bool smbsrv_setup_signing(struct smbsrv_connection *smb_conn,
DATA_BLOB *session_key,
DATA_BLOB *response)
{
if (!set_smb_signing_common(&smb_conn->signing)) {
return false;
}
return smbcli_simple_set_signing(smb_conn,
&smb_conn->signing, session_key, response);
}
bool smbsrv_init_signing(struct smbsrv_connection *smb_conn)
{
smb_conn->signing.mac_key = data_blob(NULL, 0);
if (!smbcli_set_signing_off(&smb_conn->signing)) {
return false;
}
switch (lp_server_signing(smb_conn->lp_ctx)) {
case SMB_SIGNING_OFF:
smb_conn->signing.allow_smb_signing = false;
break;
case SMB_SIGNING_SUPPORTED:
smb_conn->signing.allow_smb_signing = true;
break;
case SMB_SIGNING_REQUIRED:
smb_conn->signing.allow_smb_signing = true;
smb_conn->signing.mandatory_signing = true;
break;
case SMB_SIGNING_AUTO:
/* If we are a domain controller, SMB signing is
* really important, as it can prevent a number of
* attacks on communications between us and the
* clients */
if (lp_server_role(smb_conn->lp_ctx) == ROLE_DOMAIN_CONTROLLER) {
smb_conn->signing.allow_smb_signing = true;
smb_conn->signing.mandatory_signing = true;
} else {
/* However, it really sucks (no sendfile, CPU
* overhead) performance-wise when used on a
* file server, so disable it by default (auto
* is the default) on non-DCs */
smb_conn->signing.allow_smb_signing = false;
}
break;
}
return true;
}
/*
allocate a sequence number to a request
*/
static void req_signing_alloc_seq_num(struct smbsrv_request *req)
{
req->seq_num = req->smb_conn->signing.next_seq_num;
if (req->smb_conn->signing.signing_state != SMB_SIGNING_ENGINE_OFF) {
req->smb_conn->signing.next_seq_num += 2;
}
}
/*
called for requests that do not produce a reply of their own
*/
void smbsrv_signing_no_reply(struct smbsrv_request *req)
{
if (req->smb_conn->signing.signing_state != SMB_SIGNING_ENGINE_OFF) {
req->smb_conn->signing.next_seq_num--;
}
}
/***********************************************************
SMB signing - Simple implementation - check a MAC sent by client
************************************************************/
/**
* Check a packet supplied by the server.
* @return false if we had an established signing connection
* which had a back checksum, true otherwise
*/
bool smbsrv_signing_check_incoming(struct smbsrv_request *req)
{
bool good;
req_signing_alloc_seq_num(req);
switch (req->smb_conn->signing.signing_state)
{
case SMB_SIGNING_ENGINE_OFF:
return true;
case SMB_SIGNING_ENGINE_BSRSPYL:
case SMB_SIGNING_ENGINE_ON:
{
if (req->in.size < (HDR_SS_FIELD + 8)) {
return false;
} else {
good = check_signed_incoming_message(&req->in,
&req->smb_conn->signing.mac_key,
req->seq_num);
return signing_good(&req->smb_conn->signing,
req->seq_num+1, good);
}
}
}
return false;
}
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