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

NAME

       SELinux - NSA Security-Enhanced Linux (SELinux)

DESCRIPTION

       NSA  Security-Enhanced Linux (SELinux) is an implementation of a flexible mandatory access control architecture in the Linux operating sys-
       tem.  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(R), Role- Based Access Control, and Multi-Level Security.  Background information and tech-
       nical documentation about SELinux can be found at http://www.nsa.gov/selinux.

       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 option completely disables 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 pol-
       icy 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.

       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, two kinds of SELinux policy exist: targeted and
       strict.  The targeted policy is designed as a policy where most 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 strict policy is designed as a  pol-
       icy  where  all  processes are partitioned into fine-grained security domains and confined by policy.  It is anticipated in the future that
       other policies will be created (Multi-Level Security for example).  You can define which policy you will run  by  setting  the  SELINUXTYPE
       environment  variable  within  /etc/selinux/config.   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.  sys-
       tem-config-securitylevel 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

       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-securitylevel,  also  has  this
       capability.  The restorcon/fixfiles commands are also available for relabeling files.

AUTHOR

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

SEE ALSO

       booleans(8),   setsebool(8),   selinuxenabled(1),   togglesebool(8),   restorecon(8),   setfiles(8),   ftpd_selinux(8),   named_selinux(8),
       rsync_selinux(8), httpd_selinux(8), nfs_selinux(8), samba_selinux(8), kerberos_selinux(8), nis_selinux(8), ypbind_selinux(8)

FILES

       /etc/selinux/config

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