linux/fs/cifs/smb2misc.c

/*
 *   fs/cifs/smb2misc.c
 *
 *   Copyright (C) International Business Machines  Corp., 2002,2011
 *                 Etersoft, 2012
 *   Author(s): Steve French (sfrench@us.ibm.com)
 *              Pavel Shilovsky (pshilovsky@samba.org) 2012
 *
 *   This library is free software; you can redistribute it and/or modify
 *   it under the terms of the GNU Lesser General Public License as published
 *   by the Free Software Foundation; either version 2.1 of the License, or
 *   (at your option) any later version.
 *
 *   This library 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 Lesser General Public License for more details.
 *
 *   You should have received a copy of the GNU Lesser General Public License
 *   along with this library; if not, write to the Free Software
 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#include <linux/ctype.h>
#include "smb2pdu.h"
#include "cifsglob.h"
#include "cifsproto.h"
#include "smb2proto.h"
#include "cifs_debug.h"
#include "cifs_unicode.h"
#include "smb2status.h"

static int
check_smb2_hdr(struct smb2_hdr *hdr, __u64 mid)
{
	/*
	 * Make sure that this really is an SMB, that it is a response,
	 * and that the message ids match.
	 */
	if ((*(__le32 *)hdr->ProtocolId == SMB2_PROTO_NUMBER) &&
	    (mid == hdr->MessageId)) {
		if (hdr->Flags & SMB2_FLAGS_SERVER_TO_REDIR)
			return 0;
		else {
			/* only one valid case where server sends us request */
			if (hdr->Command == SMB2_OPLOCK_BREAK)
				return 0;
			else
				cERROR(1, "Received Request not response");
		}
	} else { /* bad signature or mid */
		if (*(__le32 *)hdr->ProtocolId != SMB2_PROTO_NUMBER)
			cERROR(1, "Bad protocol string signature header %x",
				  *(unsigned int *) hdr->ProtocolId);
		if (mid != hdr->MessageId)
			cERROR(1, "Mids do not match: %llu and %llu", mid,
				  hdr->MessageId);
	}
	cERROR(1, "Bad SMB detected. The Mid=%llu", hdr->MessageId);
	return 1;
}

/*
 *  The following table defines the expected "StructureSize" of SMB2 responses
 *  in order by SMB2 command.  This is similar to "wct" in SMB/CIFS responses.
 *
 *  Note that commands are defined in smb2pdu.h in le16 but the array below is
 *  indexed by command in host byte order
 */
static const __le16 smb2_rsp_struct_sizes[NUMBER_OF_SMB2_COMMANDS] = {
	/* SMB2_NEGOTIATE */ __constant_cpu_to_le16(65),
	/* SMB2_SESSION_SETUP */ __constant_cpu_to_le16(9),
	/* SMB2_LOGOFF */ __constant_cpu_to_le16(4),
	/* SMB2_TREE_CONNECT */ __constant_cpu_to_le16(16),
	/* SMB2_TREE_DISCONNECT */ __constant_cpu_to_le16(4),
	/* SMB2_CREATE */ __constant_cpu_to_le16(89),
	/* SMB2_CLOSE */ __constant_cpu_to_le16(60),
	/* SMB2_FLUSH */ __constant_cpu_to_le16(4),
	/* SMB2_READ */ __constant_cpu_to_le16(17),
	/* SMB2_WRITE */ __constant_cpu_to_le16(17),
	/* SMB2_LOCK */ __constant_cpu_to_le16(4),
	/* SMB2_IOCTL */ __constant_cpu_to_le16(49),
	/* BB CHECK this ... not listed in documentation */
	/* SMB2_CANCEL */ __constant_cpu_to_le16(0),
	/* SMB2_ECHO */ __constant_cpu_to_le16(4),
	/* SMB2_QUERY_DIRECTORY */ __constant_cpu_to_le16(9),
	/* SMB2_CHANGE_NOTIFY */ __constant_cpu_to_le16(9),
	/* SMB2_QUERY_INFO */ __constant_cpu_to_le16(9),
	/* SMB2_SET_INFO */ __constant_cpu_to_le16(2),
	/* BB FIXME can also be 44 for lease break */
	/* SMB2_OPLOCK_BREAK */ __constant_cpu_to_le16(24)
};

int
smb2_check_message(char *buf, unsigned int length)
{
	struct smb2_hdr *hdr = (struct smb2_hdr *)buf;
	struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
	__u64 mid = hdr->MessageId;
	__u32 len = get_rfc1002_length(buf);
	__u32 clc_len;  /* calculated length */
	int command;

	/* BB disable following printk later */
	cFYI(1, "%s length: 0x%x, smb_buf_length: 0x%x", __func__, length, len);

	/*
	 * Add function to do table lookup of StructureSize by command
	 * ie Validate the wct via smb2_struct_sizes table above
	 */

	if (length < sizeof(struct smb2_pdu)) {
		if ((length >= sizeof(struct smb2_hdr)) && (hdr->Status != 0)) {
			pdu->StructureSize2 = 0;
			/*
			 * As with SMB/CIFS, on some error cases servers may
			 * not return wct properly
			 */
			return 0;
		} else {
			cERROR(1, "Length less than SMB header size");
		}
		return 1;
	}
	if (len > CIFSMaxBufSize + MAX_SMB2_HDR_SIZE - 4) {
		cERROR(1, "SMB length greater than maximum, mid=%llu", mid);
		return 1;
	}

	if (check_smb2_hdr(hdr, mid))
		return 1;

	if (hdr->StructureSize != SMB2_HEADER_STRUCTURE_SIZE) {
		cERROR(1, "Illegal structure size %u",
			  le16_to_cpu(hdr->StructureSize));
		return 1;
	}

	command = le16_to_cpu(hdr->Command);
	if (command >= NUMBER_OF_SMB2_COMMANDS) {
		cERROR(1, "Illegal SMB2 command %d", command);
		return 1;
	}

	if (smb2_rsp_struct_sizes[command] != pdu->StructureSize2) {
		if (hdr->Status == 0 ||
		    pdu->StructureSize2 != SMB2_ERROR_STRUCTURE_SIZE2) {
			/* error packets have 9 byte structure size */
			cERROR(1, "Illegal response size %u for command %d",
				   le16_to_cpu(pdu->StructureSize2), command);
			return 1;
		}
	}

	if (4 + len != length) {
		cERROR(1, "Total length %u RFC1002 length %u mismatch mid %llu",
			  length, 4 + len, mid);
		return 1;
	}

	clc_len = smb2_calc_size(hdr);

	if (4 + len != clc_len) {
		cFYI(1, "Calculated size %u length %u mismatch mid %llu",
			clc_len, 4 + len, mid);
		/* server can return one byte more */
		if (clc_len == 4 + len + 1)
			return 0;
		return 1;
	}
	return 0;
}

/*
 * The size of the variable area depends on the offset and length fields
 * located in different fields for various SMB2 responses. SMB2 responses
 * with no variable length info, show an offset of zero for the offset field.
 */
static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = {
	/* SMB2_NEGOTIATE */ true,
	/* SMB2_SESSION_SETUP */ true,
	/* SMB2_LOGOFF */ false,
	/* SMB2_TREE_CONNECT */	false,
	/* SMB2_TREE_DISCONNECT */ false,
	/* SMB2_CREATE */ true,
	/* SMB2_CLOSE */ false,
	/* SMB2_FLUSH */ false,
	/* SMB2_READ */	true,
	/* SMB2_WRITE */ false,
	/* SMB2_LOCK */	false,
	/* SMB2_IOCTL */ true,
	/* SMB2_CANCEL */ false, /* BB CHECK this not listed in documentation */
	/* SMB2_ECHO */ false,
	/* SMB2_QUERY_DIRECTORY */ true,
	/* SMB2_CHANGE_NOTIFY */ true,
	/* SMB2_QUERY_INFO */ true,
	/* SMB2_SET_INFO */ false,
	/* SMB2_OPLOCK_BREAK */ false
};

/*
 * Returns the pointer to the beginning of the data area. Length of the data
 * area and the offset to it (from the beginning of the smb are also returned.
 */
char *
smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)
{
	*off = 0;
	*len = 0;

	/* error responses do not have data area */
	if (hdr->Status && hdr->Status != STATUS_MORE_PROCESSING_REQUIRED &&
	    (((struct smb2_err_rsp *)hdr)->StructureSize) ==
						SMB2_ERROR_STRUCTURE_SIZE2)
		return NULL;

	/*
	 * Following commands have data areas so we have to get the location
	 * of the data buffer offset and data buffer length for the particular
	 * command.
	 */
	switch (hdr->Command) {
	case SMB2_NEGOTIATE:
		*off = le16_to_cpu(
		    ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferOffset);
		*len = le16_to_cpu(
		    ((struct smb2_negotiate_rsp *)hdr)->SecurityBufferLength);
		break;
	case SMB2_SESSION_SETUP:
		*off = le16_to_cpu(
		    ((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferOffset);
		*len = le16_to_cpu(
		    ((struct smb2_sess_setup_rsp *)hdr)->SecurityBufferLength);
		break;
	case SMB2_CREATE:
		*off = le32_to_cpu(
		    ((struct smb2_create_rsp *)hdr)->CreateContextsOffset);
		*len = le32_to_cpu(
		    ((struct smb2_create_rsp *)hdr)->CreateContextsLength);
		break;
	case SMB2_QUERY_INFO:
		*off = le16_to_cpu(
		    ((struct smb2_query_info_rsp *)hdr)->OutputBufferOffset);
		*len = le32_to_cpu(
		    ((struct smb2_query_info_rsp *)hdr)->OutputBufferLength);
		break;
	case SMB2_READ:
	case SMB2_QUERY_DIRECTORY:
	case SMB2_IOCTL:
	case SMB2_CHANGE_NOTIFY:
	default:
		/* BB FIXME for unimplemented cases above */
		cERROR(1, "no length check for command");
		break;
	}

	/*
	 * Invalid length or offset probably means data area is invalid, but
	 * we have little choice but to ignore the data area in this case.
	 */
	if (*off > 4096) {
		cERROR(1, "offset %d too large, data area ignored", *off);
		*len = 0;
		*off = 0;
	} else if (*off < 0) {
		cERROR(1, "negative offset %d to data invalid ignore data area",
			  *off);
		*off = 0;
		*len = 0;
	} else if (*len < 0) {
		cERROR(1, "negative data length %d invalid, data area ignored",
			  *len);
		*len = 0;
	} else if (*len > 128 * 1024) {
		cERROR(1, "data area larger than 128K: %d", *len);
		*len = 0;
	}

	/* return pointer to beginning of data area, ie offset from SMB start */
	if ((*off != 0) && (*len != 0))
		return hdr->ProtocolId + *off;
	else
		return NULL;
}

/*
 * Calculate the size of the SMB message based on the fixed header
 * portion, the number of word parameters and the data portion of the message.
 */
unsigned int
smb2_calc_size(struct smb2_hdr *hdr)
{
	struct smb2_pdu *pdu = (struct smb2_pdu *)hdr;
	int offset; /* the offset from the beginning of SMB to data area */
	int data_length; /* the length of the variable length data area */
	/* Structure Size has already been checked to make sure it is 64 */
	int len = 4 + le16_to_cpu(pdu->hdr.StructureSize);

	/*
	 * StructureSize2, ie length of fixed parameter area has already
	 * been checked to make sure it is the correct length.
	 */
	len += le16_to_cpu(pdu->StructureSize2);

	if (has_smb2_data_area[le16_to_cpu(hdr->Command)] == false)
		goto calc_size_exit;

	smb2_get_data_area_len(&offset, &data_length, hdr);
	cFYI(1, "SMB2 data length %d offset %d", data_length, offset);

	if (data_length > 0) {
		/*
		 * Check to make sure that data area begins after fixed area,
		 * Note that last byte of the fixed area is part of data area
		 * for some commands, typically those with odd StructureSize,
		 * so we must add one to the calculation (and 4 to account for
		 * the size of the RFC1001 hdr.
		 */
		if (offset + 4 + 1 < len) {
			cERROR(1, "data area offset %d overlaps SMB2 header %d",
				  offset + 4 + 1, len);
			data_length = 0;
		} else {
			len = 4 + offset + data_length;
		}
	}
calc_size_exit:
	cFYI(1, "SMB2 len %d", len);
	return len;
}

/* Note: caller must free return buffer */
__le16 *
cifs_convert_path_to_utf16(const char *from, struct cifs_sb_info *cifs_sb)
{
	int len;
	const char *start_of_path;
	__le16 *to;

	/* Windows doesn't allow paths beginning with \ */
	if (from[0] == '\\')
		start_of_path = from + 1;
	else
		start_of_path = from;
	to = cifs_strndup_to_utf16(start_of_path, PATH_MAX, &len,
				   cifs_sb->local_nls,
				   cifs_sb->mnt_cifs_flags &
					CIFS_MOUNT_MAP_SPECIAL_CHR);
	return to;
}