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.\" Copyright (c) 2003 Joseph Koshy <jkoshy@FreeBSD.org>
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.Dd November 19, 2006
.Dt P_CANDEBUG 9
.Os
.Sh NAME
.Nm p_candebug
.Nd determine debuggability of a process
.Sh SYNOPSIS
.In sys/param.h
.In sys/proc.h
.Ft int
.Fn p_candebug "struct thread *td" "struct proc *p"
.Sh DESCRIPTION
This function can be used to determine if a given process
.Fa p
is debuggable by the thread
.Fa td .
.Sh SYSCTL VARIABLES
The following
.Xr sysctl 8
variables directly influence the behaviour of
.Fn p_candebug :
.Bl -tag -width indent
.It Va kern.securelevel
Debugging of the init process is not allowed if this variable is
.Li 1
or greater.
.It Va security.bsd.unprivileged_proc_debug
Must be set to a non-zero value to allow unprivileged processes
access to the kernel's debug facilities.
.El
.Sh RETURN VALUES
The
.Fn p_candebug
function
returns
.Li 0
if the process denoted by
.Fa p
is debuggable by thread
.Fa td ,
or a non-zero error return value otherwise.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er EACCESS
The MAC subsystem denied debuggability.
.It Bq Er EAGAIN
Process
.Fa p
is in the process of being
.Fn exec Ns 'ed.
.It Bq Er EPERM
Thread
.Fa td
lacks super-user credentials and process
.Fa p
is executing a set-user-ID or set-group-ID executable.
.It Bq Er EPERM
Thread
.Fa td
lacks super-user credentials and process
.Fa p Ns 's
group set is not a subset of
.Fa td Ns 's
effective group set.
.It Bq Er EPERM
Thread
.Fa td
lacks super-user credentials and process
.Fa p Ns 's
user IDs do not match thread
.Fa td Ns 's
effective user ID.
.It Bq Er EPERM
Process
.Fa p
denotes the initial process
.Fn initproc
and the
.Xr sysctl 8
variable
.Va kern.securelevel
is greater than zero.
.It Bq Er ESRCH
Process
.Fa p
is not visible to thread
.Fa td
as determined by
.Xr cr_seeotheruids 9
or
.Xr cr_seeothergids 9 .
.It Bq Er ESRCH
Thread
.Fa td
has been jailed and process
.Fa p
does not belong to the same jail as
.Fa td .
.It Bq Er ESRCH
The MAC subsystem denied debuggability.
.El
.Sh SEE ALSO
.Xr jail 2 ,
.Xr sysctl 8 ,
.Xr cr_seeothergids 9 ,
.Xr cr_seeotheruids 9 ,
.Xr mac 9 ,
.Xr p_cansee 9 ,
.Xr prison_check 9