git: c5e0a6bc59b9 - stable/13 - cr_bsd_visible(9): New man page

The branch stable/13 has been updated by olce:

URL: https://cgit.FreeBSD.org/src/commit/?id=c5e0a6bc59b96cb9ed98c452a0be4f012c468d26

commit c5e0a6bc59b96cb9ed98c452a0be4f012c468d26
Author:     Olivier Certner <olce.freebsd@certner.fr>
AuthorDate: 2023-08-17 23:54:40 +0000
Commit:     Olivier Certner <olce@FreeBSD.org>
CommitDate: 2023-12-21 13:36:41 +0000

    cr_bsd_visible(9): New man page
    
    Reviewed by:            bcr, pauamma_gundo.com
    Sponsored by:           Kumacom SAS
    Differential Revision:  https://reviews.freebsd.org/D40632
    
    (cherry picked from commit 0d6bf73c4f20e6ed719c29c1b382d24bb0a81a2f)
    
    Approved by:    markj (mentor)
---
 share/man/man9/Makefile         |   1 +
 share/man/man9/cr_bsd_visible.9 | 117 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 118 insertions(+)

diff --git a/share/man/man9/Makefile b/share/man/man9/Makefile
index 9d516b1f126a..18642ff86010 100644
--- a/share/man/man9/Makefile
+++ b/share/man/man9/Makefile
@@ -66,6 +66,7 @@ MAN=	accept_filter.9 \
 	copy.9 \
 	counter.9 \
 	cpuset.9 \
+	cr_bsd_visible.9 \
 	cr_cansee.9 \
 	cr_canseejailproc.9 \
 	cr_canseeothergids.9 \
diff --git a/share/man/man9/cr_bsd_visible.9 b/share/man/man9/cr_bsd_visible.9
new file mode 100644
index 000000000000..bd676e6f5705
--- /dev/null
+++ b/share/man/man9/cr_bsd_visible.9
@@ -0,0 +1,117 @@
+.\"
+.\" 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
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" 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,
+.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+.\"
+.Dd August 18, 2023
+.Dt CR_BSD_VISIBLE 9
+.Os
+.Sh NAME
+.Nm cr_bsd_visible
+.Nd determine if subjects may see entities according to BSD security policies
+.Sh SYNOPSIS
+.In sys/proc.h
+.Ft int
+.Fn cr_bsd_visible "struct ucred *u1" "struct ucred *u2"
+.Sh DESCRIPTION
+This function determines if a subject with credentials
+.Fa u1
+is denied seeing an object or subject associated to credentials
+.Fa u2
+by the following policies and associated
+.Xr sysctl 8
+knobs:
+.Bl -tag -width indent
+.It Va security.bsd.seeotheruids
+If set to 0, subjects cannot see other subjects or objects if they are not
+associated with the same real user ID.
+The corresponding internal function is
+.Xr cr_canseeotheruids 9 .
+.It Va security.bsd.seeothergids
+If set to 0, subjects cannot see other subjects or objects if they are not both
+a member of at least one common group.
+The corresponding internal function is
+.Xr cr_canseeothergids 9 .
+.It Va security.bsd.see_jail_proc
+If set to 0, subjects cannot see other subjects or objects that are not
+associated with the same jail as they are.
+The corresponding internal function is
+.Xr cr_canseejailproc 9 .
+.El
+.Pp
+As usual, the superuser (effective user ID 0) is exempt from any of these
+policies 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 .
+.Pp
+This function is intended to be used as a helper to implement
+.Xr cr_cansee 9
+and similar functions.
+.Sh RETURN VALUES
+This function returns zero if a subject with credentials
+.Fa u1
+may see a subject or object with credentials
+.Fa u2
+by the active above-mentioned policies, or
+.Er ESRCH
+otherwise.
+.Sh ERRORS
+.Bl -tag -width Er
+.It Bq Er ESRCH
+Credentials
+.Fa u1
+and
+.Fa u2
+do not have the same real user ID.
+.It Bq Er ESRCH
+Credentials
+.Fa u1
+and
+.Fa u2
+are not members of any common group
+.Po
+as determined by
+.Xr groupmember 9
+.Pc .
+.It Bq Er ESRCH
+Credentials
+.Fa u1
+and
+.Fa u2
+are not in the same jail.
+.El
+.Sh SEE ALSO
+.Xr cr_canseeotheruids 9 ,
+.Xr cr_canseeothergids 9 ,
+.Xr cr_canseejailproc 9 ,
+.Xr priv_check_cred 9 ,
+.Xr cr_cansee 9
+.Sh AUTHORS
+This function and its manual page were written by
+.An Olivier Certner Aq Mt olce.freebsd@certner.fr .