| Kees Cook | 30da4f7 | 2017-05-13 04:51:48 -0700 | [diff] [blame] | 1 | ======= |
| 2 | LoadPin |
| 3 | ======= |
| 4 | |
| Kees Cook | 9b09155 | 2016-04-20 15:46:28 -0700 | [diff] [blame] | 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 | |
| Kees Cook | 30da4f7 | 2017-05-13 04:51:48 -0700 | [diff] [blame] | 12 | The LSM is selectable at build-time with ``CONFIG_SECURITY_LOADPIN``, and |
| Kees Cook | 9b09155 | 2016-04-20 15:46:28 -0700 | [diff] [blame] | 13 | can be controlled at boot-time with the kernel command line option |
| Kees Cook | 30da4f7 | 2017-05-13 04:51:48 -0700 | [diff] [blame] | 14 | "``loadpin.enabled``". By default, it is enabled, but can be disabled at |
| 15 | boot ("``loadpin.enabled=0``"). |
| Kees Cook | 9b09155 | 2016-04-20 15:46:28 -0700 | [diff] [blame] | 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 |
| Kees Cook | 30da4f7 | 2017-05-13 04:51:48 -0700 | [diff] [blame] | 19 | created to toggle pinning: ``/proc/sys/kernel/loadpin/enabled``. (Having |
| Kees Cook | 9b09155 | 2016-04-20 15:46:28 -0700 | [diff] [blame] | 20 | a mutable filesystem means pinning is mutable too, but having the |
| 21 | sysctl allows for easy testing on systems with a mutable filesystem.) |