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ksmbd: limit pdu length size according to connection status

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Stream protocol length will never be larger than 16KB until session setup.
After session setup, the size of requests will not be larger than
16KB + SMB2 MAX WRITE size. This patch limits these invalidly oversized
requests and closes the connection immediately.

Fixes: 0626e6641f ("cifsd: add server handler for central processing and tranport layers")
Cc: stable@vger.kernel.org
Reported-by: zdi-disclosures@trendmicro.com # ZDI-CAN-18259
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Namjae Jeon 2023-01-25 00:13:20 +09:00 committed by Steve French
parent 5fde3c21cf
commit 62c487b53a
2 changed files with 18 additions and 4 deletions
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17
fs/ksmbd/connection.c
View File

@ -280,7 +280,7 @@ int ksmbd_conn_handler_loop(void *p)
{
struct ksmbd_conn *conn = (struct ksmbd_conn *)p;
struct ksmbd_transport *t = conn->transport;
unsigned int pdu_size;
unsigned int pdu_size, max_allowed_pdu_size;
char hdr_buf[4] = {0,};
int size;
@ -305,13 +305,26 @@ int ksmbd_conn_handler_loop(void *p)
pdu_size = get_rfc1002_len(hdr_buf);
ksmbd_debug(CONN, "RFC1002 header %u bytes\n", pdu_size);
if (conn->status == KSMBD_SESS_GOOD)
max_allowed_pdu_size =
SMB3_MAX_MSGSIZE + conn->vals->max_write_size;
else
max_allowed_pdu_size = SMB3_MAX_MSGSIZE;
if (pdu_size > max_allowed_pdu_size) {
pr_err_ratelimited("PDU length(%u) excceed maximum allowed pdu size(%u) on connection(%d)\n",
pdu_size, max_allowed_pdu_size,
conn->status);
break;
}
/*
* Check if pdu size is valid (min : smb header size,
* max : 0x00FFFFFF).
*/
if (pdu_size < __SMB2_HEADER_STRUCTURE_SIZE ||
pdu_size > MAX_STREAM_PROT_LEN) {
continue;
break;
}
/* 4 for rfc1002 length field */

5
fs/ksmbd/smb2pdu.h
View File

@ -24,8 +24,9 @@
#define SMB21_DEFAULT_IOSIZE (1024 * 1024)
#define SMB3_DEFAULT_TRANS_SIZE (1024 * 1024)
#define SMB3_MIN_IOSIZE (64 * 1024)
#define SMB3_MAX_IOSIZE (8 * 1024 * 1024)
#define SMB3_MIN_IOSIZE (64 * 1024)
#define SMB3_MAX_IOSIZE (8 * 1024 * 1024)
#define SMB3_MAX_MSGSIZE (4 * 4096)
/*
* Definitions for SMB2 Protocol Data Units (network frames)