ksmbd: limit pdu length size according to connection status

mainline inclusion
from mainline-v6.3-rc1
commit 62c487b5
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7CETC
CVE: NA

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=62c487b53a7ff31e322cf2874d3796b8202c54a5

--------------------------------

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: 0626e664 ("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: NNamjae Jeon <linkinjeon@kernel.org>
Signed-off-by: NSteve French <stfrench@microsoft.com>
Signed-off-by: NZhaoLong Wang <wangzhaolong1@huawei.com>

Conflicts:
    fs/ksmbd/smb2pdu.h

fs/ksmbd/connection.c

@@ -274,7 +274,7 @@ 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;
 
@@ -299,13 +299,26 @@ 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 */

fs/ksmbd/smb2pdu.h

@@ -113,8 +113,9 @@
 #define SMB21_DEFAULT_IOSIZE	(1024 * 1024)
 #define SMB3_DEFAULT_IOSIZE	(4 * 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)
 
 /*
  * SMB2 Header Definition