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Diffstat (limited to 'source4/libcli/smb2/signing.c')
| -rw-r--r-- | source4/libcli/smb2/signing.c | 139 |
1 files changed, 139 insertions, 0 deletions
diff --git a/source4/libcli/smb2/signing.c b/source4/libcli/smb2/signing.c new file mode 100644 index 0000000..b06f953 --- /dev/null +++ b/source4/libcli/smb2/signing.c @@ -0,0 +1,139 @@ +/* + 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 <gnutls/gnutls.h> +#include <gnutls/crypto.h> +#include "lib/crypto/gnutls_helpers.h" + +/* + sign an outgoing message + */ +NTSTATUS smb2_sign_message(struct smb2_request_buffer *buf, DATA_BLOB session_key) +{ + uint8_t digest[gnutls_hmac_get_len(GNUTLS_MAC_SHA256)]; + uint64_t session_id; + size_t hdr_offset; + int rc; + + if (buf->size < NBT_HDR_SIZE + SMB2_HDR_SIGNATURE + 16) { + /* can't sign non-SMB2 messages */ + return NT_STATUS_OK; + } + + hdr_offset = buf->hdr - buf->buffer; + + 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); + + rc = gnutls_hmac_fast(GNUTLS_MAC_SHA256, + session_key.data, + MIN(session_key.length, 16), + buf->hdr, + buf->size - hdr_offset, + digest); + if (rc < 0) { + return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED); + } + + DEBUG(5,("signed SMB2 message of size %u\n", (unsigned)buf->size - NBT_HDR_SIZE)); + + memcpy(buf->hdr + SMB2_HDR_SIGNATURE, digest, 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; + uint8_t digest[gnutls_hmac_get_len(GNUTLS_MAC_SHA256)]; + uint8_t sig[16]; + size_t hdr_offset; + int rc; + + if (buf->size < NBT_HDR_SIZE + SMB2_HDR_SIGNATURE + 16) { + /* can't check non-SMB2 messages */ + return NT_STATUS_OK; + } + + hdr_offset = buf->hdr - buf->buffer; + + 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); + + rc = gnutls_hmac_fast(GNUTLS_MAC_SHA256, + session_key.data, + MIN(session_key.length, 16), + buf->hdr, + buf->size - hdr_offset, + digest); + if (rc < 0) { + return gnutls_error_to_ntstatus(rc, NT_STATUS_HMAC_NOT_SUPPORTED); + } + + memcpy(buf->hdr + SMB2_HDR_SIGNATURE, digest, 16); + + if (!mem_equal_const_time(digest, sig, 16)) { + 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, digest, 16); + ZERO_ARRAY(digest); + return NT_STATUS_ACCESS_DENIED; + } + ZERO_ARRAY(digest); + + return NT_STATUS_OK; +} |