From c2e99d47973796c3fafd13079337dcadecd49d8a Mon Sep 17 00:00:00 2001 From: Namjae Jeon Date: Sun, 26 Sep 2021 21:55:02 +0900 Subject: [PATCH] ksmbd: check strictly data area in ksmbd_smb2_check_message() MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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 Cc: Ronnie Sahlberg Cc: Ralph Böhme Acked-by: Hyunchul Lee Reviewed-by: Ralph Boehme Signed-off-by: Namjae Jeon Signed-off-by: Steve French --- fs/ksmbd/smb2misc.c | 98 +++++++++++++++++++++++++---------------------------- 1 file changed, 47 insertions(+), 51 deletions(-) diff --git a/fs/ksmbd/smb2misc.c b/fs/ksmbd/smb2misc.c index 9aa46bb..9edd9c1 100644 --- a/fs/ksmbd/smb2misc.c +++ b/fs/ksmbd/smb2misc.c @@ -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, -- 2.7.4