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+.\"
+.\" SPDX-License-Identifier: BSD-2-Clause
+.\"
+.\" Copyright (c) 2023 Olivier Certner <olce.freebsd@certner.fr>
+.\"
+.\" Redistribution and use in source and binary forms, with or without
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+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
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+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR
+.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT,
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+.\"
+.Dd June 16, 2023
+.Dt CR_SEEJAILPROC 9
+.Os
+.Sh NAME
+.Nm cr_seejailproc
+.Nd may subjects see entities in a different jail?
+.Sh SYNOPSIS
+.Ft int
+.Fn cr_seejailproc "struct ucred *u1" "struct ucred *u2"
+.Sh DESCRIPTION
+.Bf -emphasis
+This function is internal.
+Its functionality is integrated into function
+.Xr cr_bsd_visibility 9 ,
+which should be called instead.
+.Ef
+.Pp
+This function checks if a subject associated to credentials
+.Fa u1
+is not denied seeing a subject or object associated to credentials
+.Fa u2
+by a policy that requires both credentials to be associated to the same jail.
+This is a restriction to the baseline jail policy that subjects in a jail can
+see subjects or objects in the same jail or any sub-jail of it.
+.Pp
+This policy is active if and only if the
+.Xr sysctl 8
+variable
+.Va security.bsd.see_jail_proc
+is non-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
+0 if the policy is disabled, the subject exempt from it or if both credentials
+are associated to the same jail,
+.Er ESRCH
+otherwise.
+.Sh SEE ALSO
+.Xr cr_bsd_visibility 9 ,
+.Xr priv_check_cred 9
+.Sh AUTHORS
+This manual page was written by
+.An Olivier Certner Aq Mt olce.freebsd@certner.fr .