SELinux: allow userspace to read policy back out of the kernel

There is interest in being able to see what the actual policy is that was
loaded into the kernel.  The patch creates a new selinuxfs file
/selinux/policy which can be read by userspace.  The actual policy that is
loaded into the kernel will be written back out to userspace.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

security/selinux/ss/avtab.h

@@ -71,6 +71,8 @@ int avtab_read_item(struct avtab *a, void *fp, struct policydb *pol,
 		    void *p);
 
 int avtab_read(struct avtab *a, void *fp, struct policydb *pol);
+int avtab_write_item(struct policydb *p, struct avtab_node *cur, void *fp);
+int avtab_write(struct policydb *p, struct avtab *a, void *fp);
 
 struct avtab_node *avtab_insert_nonunique(struct avtab *h, struct avtab_key *key,
 					  struct avtab_datum *datum);