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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: Hyunchul Lee <hyc.lee@gmail.com>
Reviewed-by: Ralph Boehme <slow@samba.org>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Namjae Jeon 2021-09-26 21:55:02 +09:00 committed by Steve French
parent 3639999011
commit c2e99d4797
1 changed files with 47 additions and 51 deletions
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98
fs/ksmbd/smb2misc.c
View File

@ -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,