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linux-next/Documentation/admin-guide/LSM/LoadPin.rst
Kees Cook 30da4f77aa doc: ReSTify LoadPin.txt
Adjusts for ReST markup and moves under LSM admin guide.

Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2017-05-18 10:33:12 -06:00

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=======
LoadPin
=======
LoadPin is a Linux Security Module that ensures all kernel-loaded files
(modules, firmware, etc) all originate from the same filesystem, with
the expectation that such a filesystem is backed by a read-only device
such as dm-verity or CDROM. This allows systems that have a verified
and/or unchangeable filesystem to enforce module and firmware loading
restrictions without needing to sign the files individually.
The LSM is selectable at build-time with ``CONFIG_SECURITY_LOADPIN``, and
can be controlled at boot-time with the kernel command line option
"``loadpin.enabled``". By default, it is enabled, but can be disabled at
boot ("``loadpin.enabled=0``").
LoadPin starts pinning when it sees the first file loaded. If the
block device backing the filesystem is not read-only, a sysctl is
created to toggle pinning: ``/proc/sys/kernel/loadpin/enabled``. (Having
a mutable filesystem means pinning is mutable too, but having the
sysctl allows for easy testing on systems with a mutable filesystem.)