ksmbd: check protocol id in ksmbd_verify_smb_message()

When second smb2 pdu has invalid protocol id, ksmbd doesn't detect it
and allow to process smb2 request. This patch add the check it in
ksmbd_verify_smb_message() and don't use protocol id of smb2 request as
protocol id of response.
Reviewed-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>
Reviewed-by: Ralph Böhme <slow@samba.org>
Reported-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/ksmbd/smb2pdu.c

@@ -433,7 +433,7 @@ static void init_chained_smb2_rsp(struct ksmbd_work *work)
 		work->compound_pfid = KSMBD_NO_FID;
 	}
 	memset((char *)rsp_hdr + 4, 0, sizeof(struct smb2_hdr) + 2);
-	rsp_hdr->ProtocolId = rcv_hdr->ProtocolId;
+	rsp_hdr->ProtocolId = SMB2_PROTO_NUMBER;
 	rsp_hdr->StructureSize = SMB2_HEADER_STRUCTURE_SIZE;
 	rsp_hdr->Command = rcv_hdr->Command;
 

fs/ksmbd/smb_common.c

@@ -129,16 +129,22 @@ int ksmbd_lookup_protocol_idx(char *str)
  *
  * check for valid smb signature and packet direction(request/response)
  *
- * Return:      0 on success, otherwise 1
+ * Return:      0 on success, otherwise -EINVAL
  */
 int ksmbd_verify_smb_message(struct ksmbd_work *work)
 {
-	struct smb2_hdr *smb2_hdr = work->request_buf;
+	struct smb2_hdr *smb2_hdr = work->request_buf + work->next_smb2_rcv_hdr_off;
+	struct smb_hdr *hdr;
 
 	if (smb2_hdr->ProtocolId == SMB2_PROTO_NUMBER)
 		return ksmbd_smb2_check_message(work);
 
-	return 0;
+	hdr = work->request_buf;
+	if (*(__le32 *)hdr->Protocol == SMB1_PROTO_NUMBER &&
+	    hdr->Command == SMB_COM_NEGOTIATE)
+		return 0;
+
+	return -EINVAL;
 }
 
 /**
@@ -265,7 +271,6 @@ static int ksmbd_negotiate_smb_dialect(void *buf)
 	return BAD_PROT_ID;
 }
 
-#define SMB_COM_NEGOTIATE	0x72
 int ksmbd_init_smb_server(struct ksmbd_work *work)
 {
 	struct ksmbd_conn *conn = work->conn;

fs/ksmbd/smb_common.h

@@ -210,6 +210,7 @@
 		FILE_READ_ATTRIBUTES | FILE_WRITE_ATTRIBUTES)
 
 #define SMB1_PROTO_NUMBER		cpu_to_le32(0x424d53ff)
+#define SMB_COM_NEGOTIATE		0x72
 
 #define SMB1_CLIENT_GUID_SIZE		(16)
 struct smb_hdr {