new in linux v3.17 commit
40e041a2c858b3caefc757e26cb85bfceae5062b
sealing allows some operations to be blocked on a file which makes
file access safer when fds are shared between processes (only
supported for shared mem fds currently)
flags:
F_SEAL_SEAL prevents further sealing
F_SEAL_SHRINK prevents file from shrinking
F_SEAL_GROW prevents file from growing
F_SEAL_WRITE prevents writes
fcntl commands:
F_GET_SEALS get the current seal flags
F_ADD_SEALS add new seal flags
#define F_CANCELLK 1029
#define F_SETPIPE_SZ 1031
#define F_GETPIPE_SZ 1032
+#define F_ADD_SEALS 1033
+#define F_GET_SEALS 1034
+
+#define F_SEAL_SEAL 0x0001
+#define F_SEAL_SHRINK 0x0002
+#define F_SEAL_GROW 0x0004
+#define F_SEAL_WRITE 0x0008
#define DN_ACCESS 0x00000001
#define DN_MODIFY 0x00000002