nixpkgs/nixos/modules/tasks/encrypted-devices.nix

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{ config, lib, ... }:
with lib;
let
fileSystems = config.system.build.fileSystems ++ config.swapDevices;
encDevs = filter (dev: dev.encrypted.enable) fileSystems;
keyedEncDevs = filter (dev: dev.encrypted.keyFile != null) encDevs;
keylessEncDevs = filter (dev: dev.encrypted.keyFile == null) encDevs;
anyEncrypted =
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foldr (j: v: v || j.encrypted.enable) false encDevs;
encryptedFSOptions = {
options.encrypted = {
enable = mkOption {
default = false;
type = types.bool;
description = "The block device is backed by an encrypted one, adds this device as a initrd luks entry.";
};
blkDev = mkOption {
default = null;
example = "/dev/sda1";
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type = types.nullOr types.str;
description = "Location of the backing encrypted device.";
};
label = mkOption {
default = null;
example = "rootfs";
type = types.nullOr types.str;
description = "Label of the unlocked encrypted device. Set <literal>fileSystems.&lt;name?&gt;.device</literal> to <literal>/dev/mapper/&lt;label&gt;</literal> to mount the unlocked device.";
};
keyFile = mkOption {
default = null;
example = "/mnt-root/root/.swapkey";
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type = types.nullOr types.str;
description = ''
Path to a keyfile used to unlock the backing encrypted
device. At the time this keyfile is accessed, the
<literal>neededForBoot</literal> filesystems (see
<literal>fileSystems.&lt;name?&gt;.neededForBoot</literal>)
will have been mounted under <literal>/mnt-root</literal>,
so the keyfile path should usually start with "/mnt-root/".
'';
};
};
};
in
{
options = {
fileSystems = mkOption {
type = with lib.types; attrsOf (submodule encryptedFSOptions);
};
swapDevices = mkOption {
type = with lib.types; listOf (submodule encryptedFSOptions);
};
};
config = mkIf anyEncrypted {
assertions = map (dev: {
assertion = dev.encrypted.label != null;
message = ''
The filesystem for ${dev.mountPoint} has encrypted.enable set to true, but no encrypted.label set
'';
}) encDevs;
boot.initrd = {
luks = {
devices =
builtins.listToAttrs (map (dev: {
name = dev.encrypted.label;
value = { device = dev.encrypted.blkDev; };
}) keylessEncDevs);
forceLuksSupportInInitrd = true;
};
postMountCommands =
concatMapStrings (dev:
"cryptsetup luksOpen --key-file ${dev.encrypted.keyFile} ${dev.encrypted.blkDev} ${dev.encrypted.label};\n"
) keyedEncDevs;
};
};
}