1======= 2LoadPin 3======= 4 5LoadPin is a Linux Security Module that ensures all kernel-loaded files 6(modules, firmware, etc) all originate from the same filesystem, with 7the expectation that such a filesystem is backed by a read-only device 8such as dm-verity or CDROM. This allows systems that have a verified 9and/or unchangeable filesystem to enforce module and firmware loading 10restrictions without needing to sign the files individually. 11 12The LSM is selectable at build-time with ``CONFIG_SECURITY_LOADPIN``, and 13can be controlled at boot-time with the kernel command line option 14"``loadpin.enabled``". By default, it is enabled, but can be disabled at 15boot ("``loadpin.enabled=0``"). 16 17LoadPin starts pinning when it sees the first file loaded. If the 18block device backing the filesystem is not read-only, a sysctl is 19created to toggle pinning: ``/proc/sys/kernel/loadpin/enabled``. (Having 20a mutable filesystem means pinning is mutable too, but having the 21sysctl allows for easy testing on systems with a mutable filesystem.) 22