| rjw | 1f88458 | 2022-01-06 17:20:42 +0800 | [diff] [blame^] | 1 | ======= |
| 2 | LoadPin |
| 3 | ======= |
| 4 | |
| 5 | LoadPin is a Linux Security Module that ensures all kernel-loaded files |
| 6 | (modules, firmware, etc) all originate from the same filesystem, with |
| 7 | the expectation that such a filesystem is backed by a read-only device |
| 8 | such as dm-verity or CDROM. This allows systems that have a verified |
| 9 | and/or unchangeable filesystem to enforce module and firmware loading |
| 10 | restrictions without needing to sign the files individually. |
| 11 | |
| 12 | The LSM is selectable at build-time with ``CONFIG_SECURITY_LOADPIN``, and |
| 13 | can be controlled at boot-time with the kernel command line option |
| 14 | "``loadpin.enabled``". By default, it is enabled, but can be disabled at |
| 15 | boot ("``loadpin.enabled=0``"). |
| 16 | |
| 17 | LoadPin starts pinning when it sees the first file loaded. If the |
| 18 | block device backing the filesystem is not read-only, a sysctl is |
| 19 | created to toggle pinning: ``/proc/sys/kernel/loadpin/enabled``. (Having |
| 20 | a mutable filesystem means pinning is mutable too, but having the |
| 21 | sysctl allows for easy testing on systems with a mutable filesystem.) |