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|
{ config, lib, pkgs, utils, ... }:
with utils;
with lib;
let
randomEncryptionCoerce = enable: { inherit enable; };
randomEncryptionOpts = { ... }: {
options = {
enable = mkOption {
default = false;
type = types.bool;
description = ''
Encrypt swap device with a random key. This way you won't have a persistent swap device.
WARNING: Don't try to hibernate when you have at least one swap partition with
this option enabled! We have no way to set the partition into which hibernation image
is saved, so if your image ends up on an encrypted one you would lose it!
WARNING #2: Do not use /dev/disk/by-uuid/… or /dev/disk/by-label/… as your swap device
when using randomEncryption as the UUIDs and labels will get erased on every boot when
the partition is encrypted. Best to use /dev/disk/by-partuuid/…
'';
};
cipher = mkOption {
default = "aes-xts-plain64";
example = "serpent-xts-plain64";
type = types.str;
description = ''
Use specified cipher for randomEncryption.
Hint: Run "cryptsetup benchmark" to see which one is fastest on your machine.
'';
};
source = mkOption {
default = "/dev/urandom";
example = "/dev/random";
type = types.str;
description = ''
Define the source of randomness to obtain a random key for encryption.
'';
};
};
};
swapCfg = {config, options, ...}: {
options = {
device = mkOption {
example = "/dev/sda3";
type = types.str;
description = "Path of the device or swap file.";
};
label = mkOption {
example = "swap";
type = types.str;
description = ''
Label of the device. Can be used instead of <varname>device</varname>.
'';
};
size = mkOption {
default = null;
example = 2048;
type = types.nullOr types.int;
description = ''
If this option is set, ‘device’ is interpreted as the
path of a swapfile that will be created automatically
with the indicated size (in megabytes).
'';
};
priority = mkOption {
default = null;
example = 2048;
type = types.nullOr types.int;
description = ''
Specify the priority of the swap device. Priority is a value between 0 and 32767.
Higher numbers indicate higher priority.
null lets the kernel choose a priority, which will show up as a negative value.
'';
};
randomEncryption = mkOption {
default = false;
example = {
enable = true;
cipher = "serpent-xts-plain64";
source = "/dev/random";
};
type = types.coercedTo types.bool randomEncryptionCoerce (types.submodule randomEncryptionOpts);
description = ''
Encrypt swap device with a random key. This way you won't have a persistent swap device.
HINT: run "cryptsetup benchmark" to test cipher performance on your machine.
WARNING: Don't try to hibernate when you have at least one swap partition with
this option enabled! We have no way to set the partition into which hibernation image
is saved, so if your image ends up on an encrypted one you would lose it!
WARNING #2: Do not use /dev/disk/by-uuid/… or /dev/disk/by-label/… as your swap device
when using randomEncryption as the UUIDs and labels will get erased on every boot when
the partition is encrypted. Best to use /dev/disk/by-partuuid/…
'';
};
discardPolicy = mkOption {
default = null;
example = "once";
type = types.nullOr (types.enum ["once" "pages" "both" ]);
description = ''
Specify the discard policy for the swap device. If "once", then the
whole swap space is discarded at swapon invocation. If "pages",
asynchronous discard on freed pages is performed, before returning to
the available pages pool. With "both", both policies are activated.
See swapon(8) for more information.
'';
};
deviceName = mkOption {
type = types.str;
internal = true;
};
realDevice = mkOption {
type = types.path;
internal = true;
};
};
config = rec {
device = mkIf options.label.isDefined
"/dev/disk/by-label/${config.label}";
deviceName = lib.replaceChars ["\\"] [""] (escapeSystemdPath config.device);
realDevice = if config.randomEncryption.enable then "/dev/mapper/${deviceName}" else config.device;
};
};
in
{
###### interface
options = {
swapDevices = mkOption {
default = [];
example = [
{ device = "/dev/hda7"; }
{ device = "/var/swapfile"; }
{ label = "bigswap"; }
];
description = ''
The swap devices and swap files. These must have been
initialised using <command>mkswap</command>. Each element
should be an attribute set specifying either the path of the
swap device or file (<literal>device</literal>) or the label
of the swap device (<literal>label</literal>, see
<command>mkswap -L</command>). Using a label is
recommended.
'';
type = types.listOf (types.submodule swapCfg);
};
};
config = mkIf ((length config.swapDevices) != 0) {
system.requiredKernelConfig = with config.lib.kernelConfig; [
(isYes "SWAP")
];
# Create missing swapfiles.
# FIXME: support changing the size of existing swapfiles.
systemd.services =
let
createSwapDevice = sw:
assert sw.device != "";
assert !(sw.randomEncryption.enable && lib.hasPrefix "/dev/disk/by-uuid" sw.device);
assert !(sw.randomEncryption.enable && lib.hasPrefix "/dev/disk/by-label" sw.device);
let realDevice' = escapeSystemdPath sw.realDevice;
in nameValuePair "mkswap-${sw.deviceName}"
{ description = "Initialisation of swap device ${sw.device}";
wantedBy = [ "${realDevice'}.swap" ];
before = [ "${realDevice'}.swap" ];
path = [ pkgs.util-linux ] ++ optional sw.randomEncryption.enable pkgs.cryptsetup;
script =
''
${optionalString (sw.size != null) ''
currentSize=$(( $(stat -c "%s" "${sw.device}" 2>/dev/null || echo 0) / 1024 / 1024 ))
if [ "${toString sw.size}" != "$currentSize" ]; then
fallocate -l ${toString sw.size}M "${sw.device}" ||
dd if=/dev/zero of="${sw.device}" bs=1M count=${toString sw.size}
if [ "${toString sw.size}" -lt "$currentSize" ]; then
truncate --size "${toString sw.size}M" "${sw.device}"
fi
chmod 0600 ${sw.device}
${optionalString (!sw.randomEncryption.enable) "mkswap ${sw.realDevice}"}
fi
''}
${optionalString sw.randomEncryption.enable ''
cryptsetup plainOpen -c ${sw.randomEncryption.cipher} -d ${sw.randomEncryption.source} ${sw.device} ${sw.deviceName}
mkswap ${sw.realDevice}
''}
'';
unitConfig.RequiresMountsFor = [ "${dirOf sw.device}" ];
unitConfig.DefaultDependencies = false; # needed to prevent a cycle
serviceConfig.Type = "oneshot";
serviceConfig.RemainAfterExit = sw.randomEncryption.enable;
serviceConfig.ExecStop = optionalString sw.randomEncryption.enable "${pkgs.cryptsetup}/bin/cryptsetup luksClose ${sw.deviceName}";
restartIfChanged = false;
};
in listToAttrs (map createSwapDevice (filter (sw: sw.size != null || sw.randomEncryption.enable) config.swapDevices));
};
}
|