| 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.) |
