HardenedBSD/share/man/man9/kernacc.9

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.\" $NetBSD: access.9,v 1.1 1996/06/16 10:38:35 pk Exp $
.\"
.\" Copyright (c) 1996 The NetBSD Foundation, Inc.
.\" All rights reserved.
.\"
.\" This code is derived from software contributed to The NetBSD Foundation
.\" by Paul Kranenburg.
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.\" This product includes software developed by the NetBSD
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.Dd June 16, 1996
.Dt KERNACC 9
.Os FreeBSD
.Sh NAME
.Nm kernacc ,
.Nm useracc
.Nd check memory regions for accessibility
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <vm/vm.h>
.Fd #include <vm/vm_extern.h>
.Ft int
.Fn kernacc "caddr_t addr" "int len" "int rw"
.Ft int
.Fn useracc "caddr_t addr" "int len" "int rw"
.Sh DESCRIPTION
The
.Fn kernacc
and
.Fn useracc
functions check whether operations of the type specified in
.Fa rw
are permitted in the range of virtual addresses given by
.Fa addr
and
.Fa len .
The possible values of
.Fa rw
are
.Dv B_READ
and
.Dv B_WRITE .
.Fn kernacc
checks addresses in the kernel address space, while
.Fn useracc
considers
.Fa addr
to represent an user space address. The process context to use for this
operation is taken from the global variable
.Va curproc .
.Pp
.Sh RETURN VALUES
Both functions return 1 if the type of access specified by
.Fa rw
is permitted. Otherwise 0 is returned.
.Pp
.Sh BUGS
The process pointer should be passed in as an argument.