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9b091556 KC |
1 | LoadPin is a Linux Security Module that ensures all kernel-loaded files |
2 | (modules, firmware, etc) all originate from the same filesystem, with | |
3 | the expectation that such a filesystem is backed by a read-only device | |
4 | such as dm-verity or CDROM. This allows systems that have a verified | |
5 | and/or unchangeable filesystem to enforce module and firmware loading | |
6 | restrictions without needing to sign the files individually. | |
7 | ||
8 | The LSM is selectable at build-time with CONFIG_SECURITY_LOADPIN, and | |
9 | can be controlled at boot-time with the kernel command line option | |
10 | "loadpin.enabled". By default, it is enabled, but can be disabled at | |
11 | boot ("loadpin.enabled=0"). | |
12 | ||
13 | LoadPin starts pinning when it sees the first file loaded. If the | |
14 | block device backing the filesystem is not read-only, a sysctl is | |
15 | created to toggle pinning: /proc/sys/kernel/loadpin/enabled. (Having | |
16 | a mutable filesystem means pinning is mutable too, but having the | |
17 | sysctl allows for easy testing on systems with a mutable filesystem.) |