selinux: handle files opened with flags 3 by checking ioctl permission

selinux: handle files opened with flags 3 by checking ioctl permission

Handle files opened with flags 3 by checking ioctl permission.

Default to returning FILE__IOCTL from file_to_av() if the f_mode has neither
FMODE_READ nor FMODE_WRITE, and thus check ioctl permission on exec or
transfer, thereby validating such descriptors early as with normal r/w
descriptors and catching leaks of them prior to attempted usage.

Signed-off-by:  Stephen Smalley <[email protected]>
Acked-by: Eric Paris <[email protected]>
Signed-off-by: James Morris <[email protected]>