82 lines
4.1 KiB
Groff
82 lines
4.1 KiB
Groff
.TH "selinux" "8" "29 Apr 2005" "dwalsh@redhat.com" "SELinux Command Line documentation"
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.SH "NAME"
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SELinux \- NSA Security-Enhanced Linux (SELinux)
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.SH "DESCRIPTION"
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NSA Security-Enhanced Linux (SELinux) is an implementation of a
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flexible mandatory access control architecture in the Linux operating
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system. The SELinux architecture provides general support for the
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enforcement of many kinds of mandatory access control policies,
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including those based on the concepts of Type Enforcement®, Role-
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Based Access Control, and Multi-Level Security. Background
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information and technical documentation about SELinux can be found at
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http://www.nsa.gov/selinux.
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The
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.I /etc/selinux/config
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configuration file controls whether SELinux is
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enabled or disabled, and if enabled, whether SELinux operates in
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permissive mode or enforcing mode. The
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.B SELINUX
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variable may be set to
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any one of disabled, permissive, or enforcing to select one of these
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options. The disabled option completely disables the SELinux kernel
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and application code, leaving the system running without any SELinux
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protection. The permissive option enables the SELinux code, but
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causes it to operate in a mode where accesses that would be denied by
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policy are permitted but audited. The enforcing option enables the
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SELinux code and causes it to enforce access denials as well as
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auditing them. Permissive mode may yield a different set of denials
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than enforcing mode, both because enforcing mode will prevent an
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operation from proceeding past the first denial and because some
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application code will fall back to a less privileged mode of operation
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if denied access.
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The
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.I /etc/selinux/config
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configuration file also controls what policy
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is active on the system. SELinux allows for multiple policies to be
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installed on the system, but only one policy may be active at any
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given time. At present, two kinds of SELinux policy exist: targeted
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and strict. The targeted policy is designed as a policy where most
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processes operate without restrictions, and only specific services are
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placed into distinct security domains that are confined by the policy.
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For example, the user would run in a completely unconfined domain
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while the named daemon or apache daemon would run in a specific domain
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tailored to its operation. The strict policy is designed as a policy
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where all processes are partitioned into fine-grained security domains
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and confined by policy. It is anticipated in the future that other
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policies will be created (Multi-Level Security for example). You can
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define which policy you will run by setting the
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.B SELINUXTYPE
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environment variable within
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.I /etc/selinux/config.
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The corresponding
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policy configuration for each such policy must be installed in the
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/etc/selinux/SELINUXTYPE/ directories.
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A given SELinux policy can be customized further based on a set of
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compile-time tunable options and a set of runtime policy booleans.
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.B system-config-securitylevel
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allows customization of these booleans and tunables.
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Many domains that are protected by SELinux also include SELinux man pages explaining how to customize their policy.
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.SH FILE LABELING
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All files, directories, devices ... have a security context/label associated with them. These context are stored in the extended attributes of the file system.
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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.
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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.
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.SH AUTHOR
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This manual page was written by Dan Walsh <dwalsh@redhat.com>.
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.SH "SEE ALSO"
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booleans(8), setsebool(8), selinuxenabled(8), 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)
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.SH FILES
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/etc/selinux/config
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