.\" $NetBSD: secmodel_extensions.9,v 1.7 2022/03/27 16:36:11 christos Exp $
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.Dd March 27, 2022
.Dt SECMODEL_EXTENSIONS 9
.Os
.Sh NAME
.Nm secmodel_extensions
.Nd extensions security model
.Sh DESCRIPTION
.Nm
implements extensions to the traditional security model based on
the original
.Bx 4.4 .
They can be used to grant additional privileges to ordinary users, or
enable specific security measures like curtain mode.
.Pp
The extensions are described below.
.Sh Curtain mode
When enabled, all returned objects will be filtered according to
the user-id requesting information about them, preventing users from
accessing objects they do not own.
.Pp
It affects the output of many commands, including
.Xr fstat 1 ,
.Xr netstat 1 ,
.Xr ps 1 ,
.Xr sockstat 1 ,
and
.Xr w 1 .
.Pp
This extension is enabled by setting
.Pa security.models.extensions.curtain
or
.Pa security.curtain
.Xr sysctl 7
to a non-zero value.
.Pp
It can be enabled at any time, but cannot be disabled
anymore when the
.Em securelevel
of the system is above 0.
.Sh Non-superuser mounts
When enabled, it allows file-systems to be mounted by an ordinary user
who owns the point
.Ar node
and has at least read access to the
.Ar special
device
.Xr mount 8
arguments.
Note that the
.Cm nosuid
and
.Cm nodev
flags must be given for non-superuser mounts.
.Pp
This extension is enabled by setting
.Pa security.models.extensions.usermount
or
.Pa vfs.generic.usermount
.Xr sysctl 7
to a non-zero value.
.Pp
It can be disabled at any time, but cannot be enabled
anymore when the
.Em securelevel
of the system is above 0.
.Sh Non-superuser control of CPU sets
When enabled, an ordinary user is allowed to control the CPU
.Xr affinity 3
of the processes and threads they own.
.Pp
This extension is enabled by setting
.Pa security.models.extensions.user_set_cpu_affinity
.Xr sysctl 7
to a non-zero value.
.Pp
It can be disabled at any time, but cannot be enabled
anymore when the
.Em securelevel
of the system is above 0.
.Sh Hardlink restrictions
Prevent hardlinks to files that the user does not own or has group access
to.
.Pp
To enable user ownership checks, set the
.Xr sysctl 7
variable
.Pa security.models.extensions.hardlink_check_uid
to a non-zero value.
.Pp
To enable group membership checks, set the
.Xr sysctl 7
variable
.Pa security.models.extensions.hardlink_check_gid
to a non-zero value.
.Pp
These variables can be enabled anytime, but cannot be disabled
anymore when the
.Em securelevel
of the system is above 0.
.Sh SEE ALSO
.Xr affinity 3 ,
.Xr sched 3 ,
.Xr sysctl 7 ,
.Xr kauth 9 ,
.Xr secmodel 9 ,
.Xr secmodel_bsd44 9 ,
.Xr secmodel_securelevel 9 ,
.Xr secmodel_suser 9
.Sh AUTHORS
.An Elad Efrat Aq Mt elad@NetBSD.org