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