Commit c2e99d47 authored by Namjae Jeon's avatar Namjae Jeon Committed by Steve French
Browse files

ksmbd: check strictly data area in ksmbd_smb2_check_message() 



When invalid data offset and data length in request,
ksmbd_smb2_check_message check strictly and doesn't allow to process such
requests.

Cc: Tom Talpey <tom@talpey.com>
Cc: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Cc: Ralph Böhme <slow@samba.org>
Acked-by: default avatarHyunchul Lee <hyc.lee@gmail.com>
Reviewed-by: default avatarRalph Boehme <slow@samba.org>
Signed-off-by: default avatarNamjae Jeon <linkinjeon@kernel.org>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 36399990

fs/ksmbd/smb2misc.c

+47 −51
Original line number Diff line number Diff line
@@ -80,18 +80,21 @@ static const bool has_smb2_data_area[NUMBER_OF_SMB2_COMMANDS] = { 
};



/*

 * 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.

 * Set length of the data area and the offset to arguments.

 * if they are invalid, return error.

 */

static char *smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr)

static int smb2_get_data_area_len(unsigned int *off, unsigned int *len,

				  struct smb2_hdr *hdr)

{

	int ret = 0;



	*off = 0;

	*len = 0;



	/* error reqeusts do not have data area */

	if (hdr->Status && hdr->Status != STATUS_MORE_PROCESSING_REQUIRED &&

	    (((struct smb2_err_rsp *)hdr)->StructureSize) == SMB2_ERROR_STRUCTURE_SIZE2_LE)

		return NULL;

		return ret;



	/*

	 * Following commands have data areas so we have to get the location
@@ -165,69 +168,60 @@ static char *smb2_get_data_area_len(int *off, int *len, struct smb2_hdr *hdr) 
	case SMB2_IOCTL:

		*off = le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputOffset);

		*len = le32_to_cpu(((struct smb2_ioctl_req *)hdr)->InputCount);



		break;

	default:

		ksmbd_debug(SMB, "no length check for command\n");

		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) {

		ksmbd_debug(SMB, "offset %d too large, data area ignored\n",

			    *off);

		*len = 0;

		*off = 0;

	} else if (*off < 0) {

		ksmbd_debug(SMB,

			    "negative offset %d to data invalid ignore data area\n",

			    *off);

		*off = 0;

		*len = 0;

	} else if (*len < 0) {

		ksmbd_debug(SMB,

			    "negative data length %d invalid, data area ignored\n",

			    *len);

		*len = 0;

	} else if (*len > 128 * 1024) {

		ksmbd_debug(SMB, "data area larger than 128K: %d\n", *len);

		*len = 0;

		ksmbd_debug(SMB, "offset %d too large\n", *off);

		ret = -EINVAL;

	} else if ((u64)*off + *len > MAX_STREAM_PROT_LEN) {

		ksmbd_debug(SMB, "Request is larger than maximum stream protocol length(%u): %llu\n",

			    MAX_STREAM_PROT_LEN, (u64)*off + *len);

		ret = -EINVAL;

	}



	/* return pointer to beginning of data area, ie offset from SMB start */

	if ((*off != 0) && (*len != 0))

		return (char *)hdr + *off;

	else

		return NULL;

	return ret;

}



/*

 * 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.

 */

static unsigned int smb2_calc_size(void *buf)

static int smb2_calc_size(void *buf, unsigned int *len)

{

	struct smb2_pdu *pdu = (struct smb2_pdu *)buf;

	struct smb2_hdr *hdr = &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 */

	unsigned int offset; /* the offset from the beginning of SMB to data area */

	unsigned int data_length; /* the length of the variable length data area */

	int ret;



	/* Structure Size has already been checked to make sure it is 64 */

	int len = le16_to_cpu(hdr->StructureSize);

	*len = le16_to_cpu(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);

	*len += le16_to_cpu(pdu->StructureSize2);

	/*

	 * StructureSize2 of smb2_lock pdu is set to 48, indicating

	 * the size of smb2 lock request with single smb2_lock_element

	 * regardless of number of locks. Subtract single

	 * smb2_lock_element for correct buffer size check.

	 */

	if (hdr->Command == SMB2_LOCK)

		*len -= sizeof(struct smb2_lock_element);



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

		goto calc_size_exit;



	smb2_get_data_area_len(&offset, &data_length, hdr);

	ksmbd_debug(SMB, "SMB2 data length %d offset %d\n", data_length,

	ret = smb2_get_data_area_len(&offset, &data_length, hdr);

	if (ret)

		return ret;

	ksmbd_debug(SMB, "SMB2 data length %u offset %u\n", data_length,

		    offset);



	if (data_length > 0) {
@@ -237,16 +231,19 @@ static unsigned int smb2_calc_size(void *buf) 
		 * for some commands, typically those with odd StructureSize,

		 * so we must add one to the calculation.

		 */

		if (offset + 1 < len)

		if (offset + 1 < *len) {

			ksmbd_debug(SMB,

				    "data area offset %d overlaps SMB2 header %d\n",

				    offset + 1, len);

		else

			len = offset + data_length;

				    "data area offset %d overlaps SMB2 header %u\n",

				    offset + 1, *len);

			return -EINVAL;

		}



		*len = offset + data_length;

	}



calc_size_exit:

	ksmbd_debug(SMB, "SMB2 len %d\n", len);

	return len;

	ksmbd_debug(SMB, "SMB2 len %u\n", *len);

	return 0;

}



static inline int smb2_query_info_req_len(struct smb2_query_info_req *h)
@@ -391,9 +388,11 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work) 
		return 1;

	}



	clc_len = smb2_calc_size(hdr);

	if (smb2_calc_size(hdr, &clc_len))

		return 1;



	if (len != clc_len) {

		/* server can return one byte more due to implied bcc[0] */

		/* client can return one byte more due to implied bcc[0] */

		if (clc_len == len + 1)

			return 0;
@@ -418,9 +417,6 @@ int ksmbd_smb2_check_message(struct ksmbd_work *work) 
			return 0;

		}



		if (command == SMB2_LOCK_HE && len == 88)

			return 0;



		ksmbd_debug(SMB,

			    "cli req too short, len %d not %d. cmd:%d mid:%llu\n",

			    len, clc_len, command,