Documentation/security/LoadPin.txt

   1 LoadPin is a Linux Security Module that ensures all kernel-loaded files
   2 (modules, firmware, etc) all originate from the same filesystem, with
   3 the expectation that such a filesystem is backed by a read-only device
   4 such as dm-verity or CDROM. This allows systems that have a verified
   5 and/or unchangeable filesystem to enforce module and firmware loading
   6 restrictions without needing to sign the files individually.
   7
   8 The LSM is selectable at build-time with CONFIG_SECURITY_LOADPIN, and
   9 can be controlled at boot-time with the kernel command line option
  10 "loadpin.enabled". By default, it is enabled, but can be disabled at
  11 boot ("loadpin.enabled=0").
  12
  13 LoadPin starts pinning when it sees the first file loaded. If the
  14 block device backing the filesystem is not read-only, a sysctl is
  15 created to toggle pinning: /proc/sys/kernel/loadpin/enabled. (Having
  16 a mutable filesystem means pinning is mutable too, but having the
  17 sysctl allows for easy testing on systems with a mutable filesystem.)