.\"	$OpenBSD: systrace.9,v 1.8 2013/08/14 06:32:32 jmc Exp $
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.\" Copyright (c) 2003 Michael Shalayeff
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.Dd $Mdocdate: August 14 2013 $
.Dt SYSTRACE 9
.Os
.Sh NAME
.Nm systrace_redirect ,
.Nm systrace_fork ,
.Nm systrace_exit
.Nd enforce policies for system calls
.Sh SYNOPSIS
.In dev/systrace.h
.Ft int
.Fn systrace_redirect "int code" "struct proc *p" "void *args" "register_t *retval"
.Ft void
.Fn systrace_fork "struct proc *oldproc" "struct proc *p"
.Ft void
.Fn systrace_exit "struct proc *p"
.Sh DESCRIPTION
These functions are used to enforce policy on the system calls as described in
.Xr systrace 1 .
.Pp
.Fn systrace_redirect
should be used to perform a system call number
.Fa code
with arguments
.Fa args
for the process
.Fa p .
The result is then put into the
.Fa retval
pointer.
A typical code sequence would be:
.Bd -literal -offset indent
#include "systrace.h"

\&...

#if NSYSTRACE > 0
	if (ISSET(p->p_flag, P_SYSTRACE))
		error = systrace_redirect(code, p, args, rval);
	else
#endif
		error = (*callp->sy_call)(p, args, rval);
.Ed
.Pp
.Fn systrace_fork
is called from the
.Xr fork1 9
function to inherit policy for the child process.
.Pp
.Fn systrace_exit
is called during the death cycle of the process to
detach the policy from the exiting process.
.Sh CODE REFERENCES
A subsystem for enforcing system call policies is implemented in
.Pa sys/dev/systrace.c .
.Sh SEE ALSO
.Xr systrace 1 ,
.Xr systrace 4 ,
.Xr syscall 9
.Sh HISTORY
The
.Nm
section manual page appeared in
.Ox 3.4 .