nixos: allow customizing the kernel RANDSTRUCT seed #53826
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GrahamcOfBorg
added
6.topic: nixos
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Nit: Exposing such a specialized feature in the general interface may seem a little ad-hoc. |
joachifm
reviewed
Jan 12, 2019
| @@ -67,6 +68,19 @@ in | |||
| description = "A list of additional patches to apply to the kernel."; | |||
| }; | |||
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| boot.kernel.randstructSeed = mkOption { | |||
| type = types.str; | |||
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It'd be neat to be able to read the seed from a file instead (e.g., if I want to share my config but not the seed)
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If you don't want to create a new module, there's |
danbst
reviewed
Jan 21, 2019
delroth
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@GrahamcOfBorg build linux_latest_hardened linux linux_latest |
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@GrahamcOfBorg test hardened |
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Motivation for this change
See #53592. RANDSTRUCT is designed to make kernel exploitation harder through diversification of the builds. Allowing users to set their own RANDSTRUCT seed differentiates their kernel build from the rest of the NixOS hardened users. In a multi-host deployment this can also be used to deploy differently seeded builds on each machine.
I was torn on whether to put this in boot/kernel.nix or create a new module in security/ for the option -- in the end I decided on boot/kernel.nix because it makes the implementation much simpler, but I'm definitely open to the "new module" option too if someone has a strong opinion about this.
Still a NixOS noob, not sure if this is the right way to do things. Let me know!
@joachifm @NeQuissimus fyi
Things done
sandboxinnix.confon non-NixOS)nix-shell -p nox --run "nox-review wip"./result/bin/)nix path-info -Sbefore and after)