/* Unix SMB/CIFS implementation. SMB2 Signing Code Copyright (C) Andrew Tridgell 2008 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 . */ #include "includes.h" #include "libcli/raw/libcliraw.h" #include "libcli/smb2/smb2.h" #include "libcli/smb2/smb2_calls.h" #include "lib/crypto/crypto.h" /* sign an outgoing message */ NTSTATUS smb2_sign_message(struct smb2_request_buffer *buf, DATA_BLOB session_key) { struct HMACSHA256Context m; uint8_t res[32]; uint64_t session_id; if (buf->size < NBT_HDR_SIZE + SMB2_HDR_SIGNATURE + 16) { /* can't sign non-SMB2 messages */ return NT_STATUS_OK; } session_id = BVAL(buf->hdr, SMB2_HDR_SESSION_ID); if (session_id == 0) { /* we don't sign messages with a zero session_id. See MS-SMB2 3.2.4.1.1 */ return NT_STATUS_OK; } if (session_key.length == 0) { DEBUG(2,("Wrong session key length %u for SMB2 signing\n", (unsigned)session_key.length)); return NT_STATUS_ACCESS_DENIED; } memset(buf->hdr + SMB2_HDR_SIGNATURE, 0, 16); SIVAL(buf->hdr, SMB2_HDR_FLAGS, IVAL(buf->hdr, SMB2_HDR_FLAGS) | SMB2_HDR_FLAG_SIGNED); ZERO_STRUCT(m); hmac_sha256_init(session_key.data, MIN(session_key.length, 16), &m); hmac_sha256_update(buf->buffer+NBT_HDR_SIZE, buf->size-NBT_HDR_SIZE, &m); hmac_sha256_final(res, &m); DEBUG(5,("signed SMB2 message of size %u\n", (unsigned)buf->size - NBT_HDR_SIZE)); memcpy(buf->hdr + SMB2_HDR_SIGNATURE, res, 16); return NT_STATUS_OK; } /* check an incoming signature */ NTSTATUS smb2_check_signature(struct smb2_request_buffer *buf, DATA_BLOB session_key) { uint64_t session_id; struct HMACSHA256Context m; uint8_t res[SHA256_DIGEST_LENGTH]; uint8_t sig[16]; if (buf->size < NBT_HDR_SIZE + SMB2_HDR_SIGNATURE + 16) { /* can't check non-SMB2 messages */ return NT_STATUS_OK; } session_id = BVAL(buf->hdr, SMB2_HDR_SESSION_ID); if (session_id == 0) { /* don't sign messages with a zero session_id. See MS-SMB2 3.2.4.1.1 */ return NT_STATUS_OK; } if (session_key.length == 0) { /* we don't have the session key yet */ return NT_STATUS_OK; } memcpy(sig, buf->hdr+SMB2_HDR_SIGNATURE, 16); memset(buf->hdr + SMB2_HDR_SIGNATURE, 0, 16); ZERO_STRUCT(m); hmac_sha256_init(session_key.data, MIN(session_key.length, 16), &m); hmac_sha256_update(buf->hdr, buf->size-NBT_HDR_SIZE, &m); hmac_sha256_final(res, &m); memcpy(buf->hdr+SMB2_HDR_SIGNATURE, sig, 16); if (memcmp(res, sig, 16) != 0) { DEBUG(0,("Bad SMB2 signature for message of size %u\n", (unsigned)buf->size-NBT_HDR_SIZE)); dump_data(0, sig, 16); dump_data(0, res, 16); return NT_STATUS_ACCESS_DENIED; } return NT_STATUS_OK; }