nfsd41: add flag checking for create_session

Teach the NFS server to reject invalid create_session flags.

Also do some minor formatting adjustments.
Signed-off-by: Mi Jinlong <mijinlong@cn.fujitsu.com>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

fs/nfsd/nfs4state.c

@@ -1515,6 +1515,9 @@ nfsd4_create_session(struct svc_rqst *rqstp,
 	bool confirm_me = false;
 	int status = 0;
 
+	if (cr_ses->flags & ~SESSION4_FLAG_MASK_A)
+		return nfserr_inval;
+
 	nfs4_lock_state();
 	unconf = find_unconfirmed_client(&cr_ses->clientid);
 	conf = find_confirmed_client(&cr_ses->clientid);

include/linux/nfs4.h

@@ -570,9 +570,11 @@ struct nfs4_sessionid {
 };
 
 /* Create Session Flags */
-#define SESSION4_PERSIST	 0x001
-#define SESSION4_BACK_CHAN 	 0x002
-#define SESSION4_RDMA		 0x004
+#define SESSION4_PERSIST	0x001
+#define SESSION4_BACK_CHAN	0x002
+#define SESSION4_RDMA		0x004
+
+#define SESSION4_FLAG_MASK_A	0x007
 
 enum state_protect_how4 {
 	SP4_NONE	= 0,