1.\" 2.\" SPDX-License-Identifier: BSD-2-Clause 3.\" 4.\" Copyright (c) 2023 Olivier Certner <olce.freebsd@certner.fr> 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE DEVELOPERS ``AS IS'' AND ANY EXPRESS OR 16.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES 17.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. 18.\" IN NO EVENT SHALL THE DEVELOPERS BE LIABLE FOR ANY DIRECT, INDIRECT, 19.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT 20.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 21.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 22.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 23.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 24.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 25.\" 26.Dd August 18, 2023 27.Dt CR_BSD_VISIBLE 9 28.Os 29.Sh NAME 30.Nm cr_bsd_visible 31.Nd determine if subjects may see entities according to BSD security policies 32.Sh SYNOPSIS 33.In sys/proc.h 34.Ft int 35.Fn cr_bsd_visible "struct ucred *u1" "struct ucred *u2" 36.Sh DESCRIPTION 37This function determines if a subject with credentials 38.Fa u1 39is denied seeing an object or subject associated to credentials 40.Fa u2 41by the following policies and associated 42.Xr sysctl 8 43knobs: 44.Bl -tag -width indent 45.It Va security.bsd.seeotheruids 46If set to 0, subjects cannot see other subjects or objects if they are not 47associated with the same real user ID. 48The corresponding internal function is 49.Xr cr_canseeotheruids 9 . 50.It Va security.bsd.seeothergids 51If set to 0, subjects cannot see other subjects or objects if they are not both 52a member of at least one common group. 53The corresponding internal function is 54.Xr cr_canseeothergids 9 . 55.It Va security.bsd.see_jail_proc 56If set to 0, subjects cannot see other subjects or objects that are not 57associated with the same jail as they are. 58The corresponding internal function is 59.Xr cr_canseejailproc 9 . 60.El 61.Pp 62As usual, the superuser (effective user ID 0) is exempt from any of these 63policies provided that the 64.Xr sysctl 8 65variable 66.Va security.bsd.suser_enabled 67is non-zero and no active MAC policy explicitly denies the exemption 68.Po 69see 70.Xr priv_check_cred 9 71.Pc . 72.Pp 73This function is intended to be used as a helper to implement 74.Xr cr_cansee 9 75and similar functions. 76.Sh RETURN VALUES 77This function returns zero if a subject with credentials 78.Fa u1 79may see a subject or object with credentials 80.Fa u2 81by the active above-mentioned policies, or 82.Er ESRCH 83otherwise. 84.Sh ERRORS 85.Bl -tag -width Er 86.It Bq Er ESRCH 87Credentials 88.Fa u1 89and 90.Fa u2 91do not have the same real user ID. 92.It Bq Er ESRCH 93Credentials 94.Fa u1 95and 96.Fa u2 97are not members of any common group 98.Po 99as determined by 100.Xr realgroupmember 9 101.Pc . 102.It Bq Er ESRCH 103Credentials 104.Fa u1 105and 106.Fa u2 107are not in the same jail. 108.El 109.Sh SEE ALSO 110.Xr cr_canseeotheruids 9 , 111.Xr cr_canseeothergids 9 , 112.Xr cr_canseejailproc 9 , 113.Xr priv_check_cred 9 , 114.Xr cr_cansee 9 115.Sh AUTHORS 116This function and its manual page were written by 117.An Olivier Certner Aq Mt olce.freebsd@certner.fr . 118