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/*
Unix SMB/CIFS implementation.
SMB Transport encryption (sealing) code.
Copyright (C) Jeremy Allison 2007.
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_common.h"
#if HAVE_KRB5
#include "lib/krb5_wrap/krb5_samba.h"
#endif
#include "auth/gensec/gensec.h"
#include "libcli/smb/smb_seal.h"
#undef malloc
/******************************************************************************
Pull out the encryption context for this packet. 0 means global context.
******************************************************************************/
NTSTATUS get_enc_ctx_num(const uint8_t *buf, uint16_t *p_enc_ctx_num)
{
if (smb_len_nbt(buf) < 8) {
return NT_STATUS_INVALID_BUFFER_SIZE;
}
if (buf[4] == 0xFF) {
if (buf[5] == 'S' && buf [6] == 'M' && buf[7] == 'B') {
/* Not an encrypted buffer. */
return NT_STATUS_NOT_FOUND;
}
if (buf[5] == 'E') {
*p_enc_ctx_num = SVAL(buf,6);
return NT_STATUS_OK;
}
}
return NT_STATUS_INVALID_NETWORK_RESPONSE;
}
/*******************************************************************
Set the length and marker of an encrypted smb packet.
********************************************************************/
static void smb_set_enclen(char *buf,int len,uint16_t enc_ctx_num)
{
_smb_setlen_tcp(buf,len);
SCVAL(buf,4,0xFF);
SCVAL(buf,5,'E');
SSVAL(buf,6,enc_ctx_num);
}
/******************************************************************************
Generic code for client and server.
Is encryption turned on ?
******************************************************************************/
bool common_encryption_on(struct smb_trans_enc_state *es)
{
return ((es != NULL) && es->enc_on);
}
/******************************************************************************
Generic code for client and server.
GENSEC decrypt an incoming buffer.
******************************************************************************/
static NTSTATUS common_gensec_decrypt_buffer(struct gensec_security *gensec,
char *buf)
{
NTSTATUS status;
size_t buf_len = smb_len_nbt(buf) + 4; /* Don't forget the 4 length bytes. */
DATA_BLOB in_buf, out_buf;
TALLOC_CTX *frame;
if (buf_len < 8) {
return NT_STATUS_BUFFER_TOO_SMALL;
}
frame = talloc_stackframe();
in_buf = data_blob_const(buf + 8, buf_len - 8);
status = gensec_unwrap(gensec, frame, &in_buf, &out_buf);
if (!NT_STATUS_IS_OK(status)) {
DEBUG(0,("common_gensec_decrypt_buffer: gensec_unwrap failed. Error %s\n",
nt_errstr(status)));
TALLOC_FREE(frame);
return status;
}
if (out_buf.length > in_buf.length) {
DEBUG(0,("common_gensec_decrypt_buffer: gensec_unwrap size (%u) too large (%u) !\n",
(unsigned int)out_buf.length,
(unsigned int)in_buf.length ));
TALLOC_FREE(frame);
return NT_STATUS_INVALID_PARAMETER;
}
memcpy(buf + 8, out_buf.data, out_buf.length);
/* Reset the length and overwrite the header. */
smb_setlen_nbt(buf, out_buf.length + 4);
TALLOC_FREE(frame);
return NT_STATUS_OK;
}
/******************************************************************************
Generic code for client and server.
NTLM encrypt an outgoing buffer. Return the encrypted pointer in ppbuf_out.
******************************************************************************/
static NTSTATUS common_gensec_encrypt_buffer(struct gensec_security *gensec,
uint16_t enc_ctx_num,
char *buf,
char **ppbuf_out)
{
NTSTATUS status;
DATA_BLOB in_buf, out_buf;
size_t buf_len = smb_len_nbt(buf) + 4; /* Don't forget the 4 length bytes. */
TALLOC_CTX *frame;
*ppbuf_out = NULL;
if (buf_len < 8) {
return NT_STATUS_BUFFER_TOO_SMALL;
}
in_buf = data_blob_const(buf + 8, buf_len - 8);
frame = talloc_stackframe();
status = gensec_wrap(gensec, frame, &in_buf, &out_buf);
if (!NT_STATUS_IS_OK(status)) {
DEBUG(0,("common_gensec_encrypt_buffer: gensec_wrap failed. Error %s\n",
nt_errstr(status)));
TALLOC_FREE(frame);
return status;
}
*ppbuf_out = (char *)malloc(out_buf.length + 8); /* We know this can't wrap. */
if (!*ppbuf_out) {
TALLOC_FREE(frame);
return NT_STATUS_NO_MEMORY;
}
memcpy(*ppbuf_out+8, out_buf.data, out_buf.length);
smb_set_enclen(*ppbuf_out, out_buf.length + 4, enc_ctx_num);
TALLOC_FREE(frame);
return NT_STATUS_OK;
}
/******************************************************************************
Generic code for client and server.
Encrypt an outgoing buffer. Return the alloced encrypted pointer in buf_out.
******************************************************************************/
NTSTATUS common_encrypt_buffer(struct smb_trans_enc_state *es, char *buffer, char **buf_out)
{
if (!common_encryption_on(es)) {
/* Not encrypting. */
*buf_out = buffer;
return NT_STATUS_OK;
}
return common_gensec_encrypt_buffer(es->gensec_security, es->enc_ctx_num, buffer, buf_out);
}
/******************************************************************************
Generic code for client and server.
Decrypt an incoming SMB buffer. Replaces the data within it.
New data must be less than or equal to the current length.
******************************************************************************/
NTSTATUS common_decrypt_buffer(struct smb_trans_enc_state *es, char *buf)
{
if (!common_encryption_on(es)) {
/* Not decrypting. */
return NT_STATUS_OK;
}
return common_gensec_decrypt_buffer(es->gensec_security, buf);
}
/******************************************************************************
Free an encryption-allocated buffer.
******************************************************************************/
void common_free_enc_buffer(struct smb_trans_enc_state *es, char *buf)
{
uint16_t enc_ctx_num;
if (!common_encryption_on(es)) {
return;
}
if (!NT_STATUS_IS_OK(get_enc_ctx_num((const uint8_t *)buf,
&enc_ctx_num))) {
return;
}
SAFE_FREE(buf);
}
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