Function vm_map_protect

freebsd/vm/vm_map.c:2739–2938

* vm_map_protect: * * Sets the protection and/or the maximum protection of the * specified address region in the target map. */

 *	specified address region in the target map.
 */
int
vm_map_protect(vm_map_t map, vm_offset_t start, vm_offset_t end,
    vm_prot_t new_prot, vm_prot_t new_maxprot, int flags)
{
	vm_map_entry_t entry, first_entry, in_tran, prev_entry;
	vm_object_t obj;
	struct ucred *cred;
	vm_prot_t old_prot;
	int rv;

	if (start == end)
		return (KERN_SUCCESS);

	if ((flags & (VM_MAP_PROTECT_SET_PROT | VM_MAP_PROTECT_SET_MAXPROT)) ==
	    (VM_MAP_PROTECT_SET_PROT | VM_MAP_PROTECT_SET_MAXPROT) &&
	    (new_prot & new_maxprot) != new_prot)
		return (KERN_OUT_OF_BOUNDS);

again:
	in_tran = NULL;
	vm_map_lock(map);

	if ((map->flags & MAP_WXORX) != 0 &&
	    (flags & VM_MAP_PROTECT_SET_PROT) != 0 &&
	    (new_prot & (VM_PROT_WRITE | VM_PROT_EXECUTE)) == (VM_PROT_WRITE |
	    VM_PROT_EXECUTE)) {
		vm_map_unlock(map);
		return (KERN_PROTECTION_FAILURE);
	}

	/*
	 * Ensure that we are not concurrently wiring pages.  vm_map_wire() may
	 * need to fault pages into the map and will drop the map lock while
	 * doing so, and the VM object may end up in an inconsistent state if we
	 * update the protection on the map entry in between faults.
	 */
	vm_map_wait_busy(map);

	VM_MAP_RANGE_CHECK(map, start, end);

	if (!vm_map_lookup_entry(map, start, &first_entry))
		first_entry = vm_map_entry_succ(first_entry);

	/*
	 * Make a first pass to check for protection violations.
	 */
	for (entry = first_entry; entry->start < end;
	    entry = vm_map_entry_succ(entry)) {
		if ((entry->eflags & MAP_ENTRY_GUARD) != 0)
			continue;
		if ((entry->eflags & MAP_ENTRY_IS_SUB_MAP) != 0) {
			vm_map_unlock(map);
			return (KERN_INVALID_ARGUMENT);
		}
		if ((flags & VM_MAP_PROTECT_SET_PROT) == 0)
			new_prot = entry->protection;
		if ((flags & VM_MAP_PROTECT_SET_MAXPROT) == 0)
			new_maxprot = entry->max_protection;