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.\" Copyright (c) 2006 Ceri Davies <ceri@FreeBSD.org>
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.\" $FreeBSD: src/share/man/man9/cr_cansee.9,v 1.1.12.2.2.1 2010/12/21 17:09:25 kensmith Exp $
.\"
.Dd November 19, 2006
.Dt CR_CANSEE 9
.Os
.Sh NAME
.Nm cr_cansee
.Nd "determine visibility of objects given their user credentials"
.Sh SYNOPSIS
.In sys/param.h
.In sys/systm.h
.In sys/ucred.h
.Ft int
.Fn cr_cansee "struct ucred *u1" "struct ucred *u2"
.Sh DESCRIPTION
This function determines the visibility of objects in the
kernel based on the real user IDs and group IDs in the credentials
.Fa u1
and
.Fa u2
associated with them.
.Pp
The visibility of objects is influenced by the
.Xr sysctl 8
variables
.Va security.bsd.see_other_gids
and
.Va security.bsd.see_other_uids ,
as per the description in
.Xr cr_seeothergids 9
and
.Xr cr_seeotheruids 9
respectively.
.Sh RETURN VALUES
This function returns zero if the object with credential
.Fa u1
can
.Dq see
the object with credential
.Fa u2 ,
or
.Er ESRCH
otherwise.
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er ESRCH
The object with credential
.Fa u1
cannot
.Dq see
the object with credential
.Fa u2 .
.It Bq Er ESRCH
The object with credential
.Fa u1
has been jailed and the object with credential
.Fa u2
does not belong to the same jail as
.Fa u1 .
.It Bq Er ESRCH
The MAC subsystem denied visibility.
.El
.Sh SEE ALSO
.Xr cr_seeothergids 9 ,
.Xr cr_seeotheruids 9 ,
.Xr mac 9 ,
.Xr p_cansee 9