Function mac_proc_vm_revoke_recurse

freebsd/security/mac/mac_process.c:251–372

}

static void
mac_proc_vm_revoke_recurse(struct thread *td, struct ucred *cred,
    struct vm_map *map)
{
	vm_map_entry_t prev, vme;
	int result;
	vm_prot_t revokeperms;
	vm_object_t backing_object, object;
	vm_ooffset_t offset;
	struct vnode *vp;
	struct mount *mp;

	if (!mac_mmap_revocation)
		return;

	prev = &map->header;
	vm_map_lock(map);
	for (vme = vm_map_entry_first(map); vme != &map->header;
	    prev = vme, vme = vm_map_entry_succ(prev)) {
		if (vme->eflags & MAP_ENTRY_IS_SUB_MAP) {
			mac_proc_vm_revoke_recurse(td, cred,
			    vme->object.sub_map);
			continue;
		}
		/*
		 * Skip over entries that obviously are not shared.
		 */
		if (vme->eflags & (MAP_ENTRY_COW | MAP_ENTRY_NOSYNC) ||
		    !vme->max_protection)
			continue;
		/*
		 * Drill down to the deepest backing object.
		 */
		offset = vme->offset;
		object = vme->object.vm_object;
		if (object == NULL)
			continue;
		VM_OBJECT_RLOCK(object);
		while ((backing_object = object->backing_object) != NULL) {
			VM_OBJECT_RLOCK(backing_object);
			offset += object->backing_object_offset;
			VM_OBJECT_RUNLOCK(object);
			object = backing_object;
		}
		VM_OBJECT_RUNLOCK(object);
		/*
		 * At the moment, vm_maps and objects aren't considered by
		 * the MAC system, so only things with backing by a normal
		 * object (read: vnodes) are checked.
		 */
		if (object->type != OBJT_VNODE)
			continue;
		vp = (struct vnode *)object->handle;
		vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
		result = vme->max_protection;
		mac_vnode_check_mmap_downgrade(cred, vp, &result);
		VOP_UNLOCK(vp);
		/*