selinux(8) — Linux manual page

NAME | DESCRIPTION | FILE LABELING | AUTHOR | FILES | SEE ALSO | COLOPHON

selinux(8)         SELinux Command Line documentation         selinux(8)

NAME         top

       SELinux - NSA Security-Enhanced Linux (SELinux)

DESCRIPTION         top

       NSA Security-Enhanced Linux (SELinux) is an implementation of a
       flexible mandatory access control architecture in the Linux
       operating system.  The SELinux architecture provides general
       support for the enforcement of many kinds of mandatory access
       control policies, including those based on the concepts of Type
       Enforcement®, Role- Based Access Control, and Multi-Level
       Security.  Background information and technical documentation
       about SELinux can be found at https://github.com/SELinuxProject.

       The /etc/selinux/config configuration file controls whether
       SELinux is enabled or disabled, and if enabled, whether SELinux
       operates in permissive mode or enforcing mode.  The SELINUX
       variable may be set to any one of disabled, permissive, or
       enforcing to select one of these options.  The disabled disables
       most of the SELinux kernel and application code, leaving the
       system running without any SELinux protection.  The permissive
       option enables the SELinux code, but causes it to operate in a
       mode where accesses that would be denied by policy are permitted
       but audited.  The enforcing option enables the SELinux code and
       causes it to enforce access denials as well as auditing them.
       permissive mode may yield a different set of denials than
       enforcing mode, both because enforcing mode will prevent an
       operation from proceeding past the first denial and because some
       application code will fall back to a less privileged mode of
       operation if denied access.

       NOTE: Disabling SELinux by setting SELINUX=disabled in
       /etc/selinux/config is deprecated and depending on kernel version
       and configuration it might not lead to SELinux being completely
       disabled.  Specifically, the SELinux hooks will still be executed
       internally, but the SELinux policy will not be loaded and no
       operation will be denied.  In such state, the system will act as
       if SELinux was disabled, although some operations might behave
       slightly differently.  To properly disable SELinux, it is
       recommended to use the selinux=0 kernel boot option instead.  In
       that case SELinux will be disabled regardless of what is set in
       the /etc/selinux/config file.

       The /etc/selinux/config configuration file also controls what
       policy is active on the system.  SELinux allows for multiple
       policies to be installed on the system, but only one policy may
       be active at any given time.  At present, multiple kinds of
       SELinux policy exist: targeted, mls for example.  The targeted
       policy is designed as a policy where most user processes operate
       without restrictions, and only specific services are placed into
       distinct security domains that are confined by the policy.  For
       example, the user would run in a completely unconfined domain
       while the named daemon or apache daemon would run in a specific
       domain tailored to its operation.  The MLS (Multi-Level Security)
       policy is designed as a policy where all processes are
       partitioned into fine-grained security domains and confined by
       policy.  MLS also supports the Bell And LaPadula model, where
       processes are not only confined by the type but also the level of
       the data.

       You can define which policy you will run by setting the
       SELINUXTYPE environment variable within /etc/selinux/config.  You
       must reboot and possibly relabel if you change the policy type to
       have it take effect on the system.  The corresponding policy
       configuration for each such policy must be installed in the
       /etc/selinux/{SELINUXTYPE}/ directories.

       A given SELinux policy can be customized further based on a set
       of compile-time tunable options and a set of runtime policy
       booleans.  system-config-selinux allows customization of these
       booleans and tunables.

       Many domains that are protected by SELinux also include SELinux
       man pages explaining how to customize their policy.

FILE LABELING         top

       All files, directories, devices ... have a security context/label
       associated with them.  These context are stored in the extended
       attributes of the file system.  Problems with SELinux often arise
       from the file system being mislabeled. This can be caused by
       booting the machine with a non SELinux kernel.  If you see an
       error message containing file_t, that is usually a good indicator
       that you have a serious problem with file system labeling.

       The best way to relabel the file system is to create the flag
       file /.autorelabel and reboot.  system-config-selinux, also has
       this capability.  The restorecon/fixfiles commands are also
       available for relabeling files.

       Please note that using mount flag nosuid also disables SELinux
       domain transitions, unless permission nosuid_transition is used
       in the policy to allow this, which in turn needs also policy
       capability nnp_nosuid_transition.

AUTHOR         top

       This manual page was written by Dan Walsh <dwalsh@redhat.com>.

FILES         top

       /etc/selinux/config

SEE ALSO         top

       booleans(8), setsebool(8), sepolicy(8), system-config-selinux(8),
       togglesebool(8), restorecon(8), fixfiles(8), setfiles(8),
       semanage(8), sepolicy(8)

       Every confined service on the system has a man page in the
       following format:

       <servicename>_selinux(8)

       For example, httpd has the httpd_selinux(8) man page.

       man -k selinux

       Will list all SELinux man pages.

COLOPHON         top

       This page is part of the selinux (Security-Enhanced Linux user-
       space libraries and tools) project.  Information about the
       project can be found at 
       ⟨https://github.com/SELinuxProject/selinux/wiki⟩.  If you have a
       bug report for this manual page, see
       ⟨https://github.com/SELinuxProject/selinux/wiki/Contributing⟩.
       This page was obtained from the project's upstream Git repository
       ⟨https://github.com/SELinuxProject/selinux⟩ on 2021-08-27.  (At
       that time, the date of the most recent commit that was found in
       the repository was 2021-08-23.)  If you discover any rendering
       problems in this HTML version of the page, or you believe there
       is a better or more up-to-date source for the page, or you have
       corrections or improvements to the information in this COLOPHON
       (which is not part of the original manual page), send a mail to
       man-pages@man7.org

dwalsh@redhat.com              29 Apr 2005                    selinux(8)

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