diff options
Diffstat (limited to 'source4/libcli/smb2/signing.c')
| -rw-r--r-- | source4/libcli/smb2/signing.c | 165 |
1 files changed, 165 insertions, 0 deletions
diff --git a/source4/libcli/smb2/signing.c b/source4/libcli/smb2/signing.c new file mode 100644 index 0000000000..01f7576134 --- /dev/null +++ b/source4/libcli/smb2/signing.c @@ -0,0 +1,165 @@ +/* + Unix SMB/CIFS implementation. + + SMB2 Signing Code + + Copyright (C) Andrew Tridgell <tridge@samba.org> 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 <http://www.gnu.org/licenses/>. +*/ + +#include "includes.h" +#include "libcli/raw/libcliraw.h" +#include "libcli/smb2/smb2.h" +#include "libcli/smb2/smb2_calls.h" +#include "heimdal/lib/hcrypto/sha.h" + +/* + NOTE: this code does not yet interoperate with the windows SMB2 + implementation. We are waiting on feedback on the docs to find out + why + */ + + +/* + setup signing on a transport + */ +NTSTATUS smb2_start_signing(struct smb2_transport *transport) +{ + if (transport->signing.session_key.length != 16) { + DEBUG(2,("Wrong session key length %u for SMB2 signing\n", + (unsigned)transport->signing.session_key.length)); + return NT_STATUS_ACCESS_DENIED; + } + + transport->signing.signing_started = true; + return NT_STATUS_OK; +} + +/* + sign an outgoing message + */ +NTSTATUS smb2_sign_message(struct smb2_request *req) +{ + struct smb2_request_buffer *buf = &req->out; + uint64_t session_id; + SHA256_CTX m; + uint8_t res[32]; + + if (!req->transport->signing.doing_signing || + !req->transport->signing.signing_started) { + return NT_STATUS_OK; + } + + 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 (req->transport->signing.session_key.length != 16) { + DEBUG(2,("Wrong session key length %u for SMB2 signing\n", + (unsigned)req->transport->signing.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); + SHA256_Init(&m); + SHA256_Update(&m, req->transport->signing.session_key.data, + req->transport->signing.session_key.length); + SHA256_Update(&m, buf->buffer+NBT_HDR_SIZE, buf->size-NBT_HDR_SIZE); + 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); + + if (DEBUGLVL(5)) { + /* check our own signature */ + smb2_check_signature(req->transport, buf->buffer, buf->size); + } + + return NT_STATUS_OK; +} + +/* + check an incoming signature + */ +NTSTATUS smb2_check_signature(struct smb2_transport *transport, + uint8_t *buffer, uint_t length) +{ + uint64_t session_id; + SHA256_CTX m; + uint8_t res[SHA256_DIGEST_LENGTH]; + uint8_t sig[16]; + + if (!transport->signing.signing_started || + !transport->signing.doing_signing) { + return NT_STATUS_OK; + } + + if (length < NBT_HDR_SIZE + SMB2_HDR_SIGNATURE + 16) { + /* can't check non-SMB2 messages */ + return NT_STATUS_OK; + } + + session_id = BVAL(buffer+NBT_HDR_SIZE, 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 (transport->signing.session_key.length == 0) { + /* we don't have the session key yet */ + return NT_STATUS_OK; + } + + if (transport->signing.session_key.length != 16) { + DEBUG(2,("Wrong session key length %u for SMB2 signing\n", + (unsigned)transport->signing.session_key.length)); + return NT_STATUS_ACCESS_DENIED; + } + + memcpy(sig, buffer+NBT_HDR_SIZE+SMB2_HDR_SIGNATURE, 16); + + memset(buffer + NBT_HDR_SIZE + SMB2_HDR_SIGNATURE, 0, 16); + + ZERO_STRUCT(m); + SHA256_Init(&m); + SHA256_Update(&m, transport->signing.session_key.data, 16); + SHA256_Update(&m, buffer+NBT_HDR_SIZE, length-NBT_HDR_SIZE); + SHA256_Final(res, &m); + + memcpy(buffer+NBT_HDR_SIZE+SMB2_HDR_SIGNATURE, sig, 16); + + if (memcmp(res, sig, 16) != 0) { + DEBUG(0,("Bad SMB2 signature for message of size %u\n", length)); + dump_data(0, sig, 16); + dump_data(0, res, 16); + return NT_STATUS_ACCESS_DENIED; + } + + return NT_STATUS_OK; +} |