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.\" Copyright (c) 2003 Joseph Koshy <jkoshy@FreeBSD.org>
.\" Copyright (c) 2023 Olivier Certner <olce.freebsd@certner.fr>
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.Dd August 18, 2023
.Dt CR_CANSEEOTHERUIDS 9
.Os
.Sh NAME
.Nm cr_canseeotheruids
.Nd determine if subjects may see entities with differing user ID
.Sh SYNOPSIS
.Ft int
.Fn cr_canseeotheruids "struct ucred *u1" "struct ucred *u2"
.Sh DESCRIPTION
.Bf -emphasis
This function is internal.
Its functionality is integrated into the function
.Xr cr_bsd_visible 9 ,
which should be called instead.
.Ef
.Pp
This function checks if a subject associated to credentials
.Fa u1
is denied seeing a subject or object associated to credentials
.Fa u2
by a policy that requires both credentials to have the same real user ID.
.Pp
This policy is active if and only if the
.Xr sysctl 8
variable
.Va security.bsd.see_other_uids
is set to zero.
.Pp
As usual, the superuser (effective user ID 0) is exempt from this policy
provided that the
.Xr sysctl 8
variable
.Va security.bsd.suser_enabled
is non-zero and no active MAC policy explicitly denies the exemption
.Po
see
.Xr priv_check_cred 9
.Pc .
.Sh RETURN VALUES
The
.Fn cr_canseeotheruids
function returns 0 if the policy is disabled, both credentials have the same
real user ID, or if
.Fa u1
has privilege exempting it from the policy.
Otherwise, it returns
.Er ESRCH .
.Sh SEE ALSO
.Xr cr_bsd_visible 9 ,
.Xr priv_check_cred 9