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luksroot.nix
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luksroot.nix
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{ config, options, lib, pkgs, ... }:
with lib;
let
luks = config.boot.initrd.luks;
kernelPackages = config.boot.kernelPackages;
defaultPrio = (mkOptionDefault {}).priority;
commonFunctions = ''
die() {
echo "$@" >&2
exit 1
}
dev_exist() {
local target="$1"
if [ -e $target ]; then
return 0
else
local uuid=$(echo -n $target | sed -e 's,UUID=\(.*\),\1,g')
blkid --uuid $uuid >/dev/null
return $?
fi
}
wait_target() {
local name="$1"
local target="$2"
local secs="''${3:-10}"
local desc="''${4:-$name $target to appear}"
if ! dev_exist $target; then
echo -n "Waiting $secs seconds for $desc..."
local success=false;
for try in $(seq $secs); do
echo -n "."
sleep 1
if dev_exist $target; then
success=true
break
fi
done
if [ $success == true ]; then
echo " - success";
return 0
else
echo " - failure";
return 1
fi
fi
return 0
}
wait_yubikey() {
local secs="''${1:-10}"
ykinfo -v 1>/dev/null 2>&1
if [ $? != 0 ]; then
echo -n "Waiting $secs seconds for YubiKey to appear..."
local success=false
for try in $(seq $secs); do
echo -n .
sleep 1
ykinfo -v 1>/dev/null 2>&1
if [ $? == 0 ]; then
success=true
break
fi
done
if [ $success == true ]; then
echo " - success";
return 0
else
echo " - failure";
return 1
fi
fi
return 0
}
wait_gpgcard() {
local secs="''${1:-10}"
gpg --card-status > /dev/null 2> /dev/null
if [ $? != 0 ]; then
echo -n "Waiting $secs seconds for GPG Card to appear"
local success=false
for try in $(seq $secs); do
echo -n .
sleep 1
gpg --card-status > /dev/null 2> /dev/null
if [ $? == 0 ]; then
success=true
break
fi
done
if [ $success == true ]; then
echo " - success";
return 0
else
echo " - failure";
return 1
fi
fi
return 0
}
'';
preCommands = ''
# A place to store crypto things
# A ramfs is used here to ensure that the file used to update
# the key slot with cryptsetup will never get swapped out.
# Warning: Do NOT replace with tmpfs!
mkdir -p /crypt-ramfs
mount -t ramfs none /crypt-ramfs
# Cryptsetup locking directory
mkdir -p /run/cryptsetup
# For YubiKey salt storage
mkdir -p /crypt-storage
${optionalString luks.gpgSupport ''
export GPG_TTY=$(tty)
export GNUPGHOME=/crypt-ramfs/.gnupg
gpg-agent --daemon --scdaemon-program $out/bin/scdaemon > /dev/null 2> /dev/null
''}
# Disable all input echo for the whole stage. We could use read -s
# instead but that would occasionally leak characters between read
# invocations.
stty -echo
'';
postCommands = ''
stty echo
umount /crypt-storage 2>/dev/null
umount /crypt-ramfs 2>/dev/null
'';
openCommand = name: dev: assert name == dev.name;
let
csopen = "cryptsetup luksOpen ${dev.device} ${dev.name}"
+ optionalString dev.allowDiscards " --allow-discards"
+ optionalString dev.bypassWorkqueues " --perf-no_read_workqueue --perf-no_write_workqueue"
+ optionalString (dev.header != null) " --header=${dev.header}";
cschange = "cryptsetup luksChangeKey ${dev.device} ${optionalString (dev.header != null) "--header=${dev.header}"}";
fido2luksCredentials = dev.fido2.credentials ++ optional (dev.fido2.credential != null) dev.fido2.credential;
in ''
# Wait for luksRoot (and optionally keyFile and/or header) to appear, e.g.
# if on a USB drive.
wait_target "device" ${dev.device} || die "${dev.device} is unavailable"
${optionalString (dev.header != null) ''
wait_target "header" ${dev.header} || die "${dev.header} is unavailable"
''}
try_empty_passphrase() {
${if dev.tryEmptyPassphrase then ''
echo "Trying empty passphrase!"
echo "" | ${csopen}
cs_status=$?
if [ $cs_status -eq 0 ]; then
return 0
else
return 1
fi
'' else "return 1"}
}
do_open_passphrase() {
local passphrase
while true; do
echo -n "Passphrase for ${dev.device}: "
passphrase=
while true; do
if [ -e /crypt-ramfs/passphrase ]; then
echo "reused"
passphrase=$(cat /crypt-ramfs/passphrase)
break
else
# ask cryptsetup-askpass
echo -n "${dev.device}" > /crypt-ramfs/device
# and try reading it from /dev/console with a timeout
IFS= read -t 1 -r passphrase
if [ -n "$passphrase" ]; then
${if luks.reusePassphrases then ''
# remember it for the next device
echo -n "$passphrase" > /crypt-ramfs/passphrase
'' else ''
# Don't save it to ramfs. We are very paranoid
''}
echo
break
fi
fi
done
echo -n "Verifying passphrase for ${dev.device}..."
echo -n "$passphrase" | ${csopen} --key-file=-
if [ $? == 0 ]; then
echo " - success"
${if luks.reusePassphrases then ''
# we don't rm here because we might reuse it for the next device
'' else ''
rm -f /crypt-ramfs/passphrase
''}
break
else
echo " - failure"
# ask for a different one
rm -f /crypt-ramfs/passphrase
fi
done
}
# LUKS
open_normally() {
${if (dev.keyFile != null) then ''
if wait_target "key file" ${dev.keyFile}; then
${csopen} --key-file=${dev.keyFile} \
${optionalString (dev.keyFileSize != null) "--keyfile-size=${toString dev.keyFileSize}"} \
${optionalString (dev.keyFileOffset != null) "--keyfile-offset=${toString dev.keyFileOffset}"}
cs_status=$?
if [ $cs_status -ne 0 ]; then
echo "Key File ${dev.keyFile} failed!"
if ! try_empty_passphrase; then
${if dev.fallbackToPassword then "echo" else "die"} "${dev.keyFile} is unavailable"
echo " - failing back to interactive password prompt"
do_open_passphrase
fi
fi
else
# If the key file never shows up we should also try the empty passphrase
if ! try_empty_passphrase; then
${if dev.fallbackToPassword then "echo" else "die"} "${dev.keyFile} is unavailable"
echo " - failing back to interactive password prompt"
do_open_passphrase
fi
fi
'' else ''
if ! try_empty_passphrase; then
do_open_passphrase
fi
''}
}
${optionalString (luks.yubikeySupport && (dev.yubikey != null)) ''
# YubiKey
rbtohex() {
( od -An -vtx1 | tr -d ' \n' )
}
hextorb() {
( tr '[:lower:]' '[:upper:]' | sed -e 's/\([0-9A-F]\{2\}\)/\\\\\\x\1/gI' | xargs printf )
}
do_open_yubikey() {
# Make all of these local to this function
# to prevent their values being leaked
local salt
local iterations
local k_user
local challenge
local response
local k_luks
local opened
local new_salt
local new_iterations
local new_challenge
local new_response
local new_k_luks
mount -t ${dev.yubikey.storage.fsType} ${dev.yubikey.storage.device} /crypt-storage || \
die "Failed to mount YubiKey salt storage device"
salt="$(cat /crypt-storage${dev.yubikey.storage.path} | sed -n 1p | tr -d '\n')"
iterations="$(cat /crypt-storage${dev.yubikey.storage.path} | sed -n 2p | tr -d '\n')"
challenge="$(echo -n $salt | openssl-wrap dgst -binary -sha512 | rbtohex)"
response="$(ykchalresp -${toString dev.yubikey.slot} -x $challenge 2>/dev/null)"
for try in $(seq 3); do
${optionalString dev.yubikey.twoFactor ''
echo -n "Enter two-factor passphrase: "
k_user=
while true; do
if [ -e /crypt-ramfs/passphrase ]; then
echo "reused"
k_user=$(cat /crypt-ramfs/passphrase)
break
else
# Try reading it from /dev/console with a timeout
IFS= read -t 1 -r k_user
if [ -n "$k_user" ]; then
${if luks.reusePassphrases then ''
# Remember it for the next device
echo -n "$k_user" > /crypt-ramfs/passphrase
'' else ''
# Don't save it to ramfs. We are very paranoid
''}
echo
break
fi
fi
done
''}
if [ ! -z "$k_user" ]; then
k_luks="$(echo -n $k_user | pbkdf2-sha512 ${toString dev.yubikey.keyLength} $iterations $response | rbtohex)"
else
k_luks="$(echo | pbkdf2-sha512 ${toString dev.yubikey.keyLength} $iterations $response | rbtohex)"
fi
echo -n "$k_luks" | hextorb | ${csopen} --key-file=-
if [ $? == 0 ]; then
opened=true
${if luks.reusePassphrases then ''
# We don't rm here because we might reuse it for the next device
'' else ''
rm -f /crypt-ramfs/passphrase
''}
break
else
opened=false
echo "Authentication failed!"
fi
done
[ "$opened" == false ] && die "Maximum authentication errors reached"
echo -n "Gathering entropy for new salt (please enter random keys to generate entropy if this blocks for long)..."
for i in $(seq ${toString dev.yubikey.saltLength}); do
byte="$(dd if=/dev/random bs=1 count=1 2>/dev/null | rbtohex)";
new_salt="$new_salt$byte";
echo -n .
done;
echo "ok"
new_iterations="$iterations"
${optionalString (dev.yubikey.iterationStep > 0) ''
new_iterations="$(($new_iterations + ${toString dev.yubikey.iterationStep}))"
''}
new_challenge="$(echo -n $new_salt | openssl-wrap dgst -binary -sha512 | rbtohex)"
new_response="$(ykchalresp -${toString dev.yubikey.slot} -x $new_challenge 2>/dev/null)"
if [ -z "$new_response" ]; then
echo "Warning: Unable to generate new challenge response, current challenge persists!"
umount /crypt-storage
return
fi
if [ ! -z "$k_user" ]; then
new_k_luks="$(echo -n $k_user | pbkdf2-sha512 ${toString dev.yubikey.keyLength} $new_iterations $new_response | rbtohex)"
else
new_k_luks="$(echo | pbkdf2-sha512 ${toString dev.yubikey.keyLength} $new_iterations $new_response | rbtohex)"
fi
echo -n "$new_k_luks" | hextorb > /crypt-ramfs/new_key
echo -n "$k_luks" | hextorb | ${cschange} --key-file=- /crypt-ramfs/new_key
if [ $? == 0 ]; then
echo -ne "$new_salt\n$new_iterations" > /crypt-storage${dev.yubikey.storage.path}
sync /crypt-storage${dev.yubikey.storage.path}
else
echo "Warning: Could not update LUKS key, current challenge persists!"
fi
rm -f /crypt-ramfs/new_key
umount /crypt-storage
}
open_with_hardware() {
if wait_yubikey ${toString dev.yubikey.gracePeriod}; then
do_open_yubikey
else
echo "No YubiKey found, falling back to non-YubiKey open procedure"
open_normally
fi
}
''}
${optionalString (luks.gpgSupport && (dev.gpgCard != null)) ''
do_open_gpg_card() {
# Make all of these local to this function
# to prevent their values being leaked
local pin
local opened
gpg --import /gpg-keys/${dev.device}/pubkey.asc > /dev/null 2> /dev/null
gpg --card-status > /dev/null 2> /dev/null
for try in $(seq 3); do
echo -n "PIN for GPG Card associated with device ${dev.device}: "
pin=
while true; do
if [ -e /crypt-ramfs/passphrase ]; then
echo "reused"
pin=$(cat /crypt-ramfs/passphrase)
break
else
# and try reading it from /dev/console with a timeout
IFS= read -t 1 -r pin
if [ -n "$pin" ]; then
${if luks.reusePassphrases then ''
# remember it for the next device
echo -n "$pin" > /crypt-ramfs/passphrase
'' else ''
# Don't save it to ramfs. We are very paranoid
''}
echo
break
fi
fi
done
echo -n "Verifying passphrase for ${dev.device}..."
echo -n "$pin" | gpg -q --batch --passphrase-fd 0 --pinentry-mode loopback -d /gpg-keys/${dev.device}/cryptkey.gpg 2> /dev/null | ${csopen} --key-file=- > /dev/null 2> /dev/null
if [ $? == 0 ]; then
echo " - success"
${if luks.reusePassphrases then ''
# we don't rm here because we might reuse it for the next device
'' else ''
rm -f /crypt-ramfs/passphrase
''}
break
else
echo " - failure"
# ask for a different one
rm -f /crypt-ramfs/passphrase
fi
done
[ "$opened" == false ] && die "Maximum authentication errors reached"
}
open_with_hardware() {
if wait_gpgcard ${toString dev.gpgCard.gracePeriod}; then
do_open_gpg_card
else
echo "No GPG Card found, falling back to normal open procedure"
open_normally
fi
}
''}
${optionalString (luks.fido2Support && fido2luksCredentials != []) ''
open_with_hardware() {
local passsphrase
${if dev.fido2.passwordLess then ''
export passphrase=""
'' else ''
read -rsp "FIDO2 salt for ${dev.device}: " passphrase
echo
''}
${optionalString (lib.versionOlder kernelPackages.kernel.version "5.4") ''
echo "On systems with Linux Kernel < 5.4, it might take a while to initialize the CRNG, you might want to use linuxPackages_latest."
echo "Please move your mouse to create needed randomness."
''}
echo "Waiting for your FIDO2 device..."
fido2luks open${optionalString dev.allowDiscards " --allow-discards"} ${dev.device} ${dev.name} "${builtins.concatStringsSep "," fido2luksCredentials}" --await-dev ${toString dev.fido2.gracePeriod} --salt string:$passphrase
if [ $? -ne 0 ]; then
echo "No FIDO2 key found, falling back to normal open procedure"
open_normally
fi
}
''}
# commands to run right before we mount our device
${dev.preOpenCommands}
${if (luks.yubikeySupport && (dev.yubikey != null)) || (luks.gpgSupport && (dev.gpgCard != null)) || (luks.fido2Support && fido2luksCredentials != []) then ''
open_with_hardware
'' else ''
open_normally
''}
# commands to run right after we mounted our device
${dev.postOpenCommands}
'';
askPass = pkgs.writeScriptBin "cryptsetup-askpass" ''
#!/bin/sh
${commonFunctions}
while true; do
wait_target "luks" /crypt-ramfs/device 10 "LUKS to request a passphrase" || die "Passphrase is not requested now"
device=$(cat /crypt-ramfs/device)
echo -n "Passphrase for $device: "
IFS= read -rs passphrase
echo
rm /crypt-ramfs/device
echo -n "$passphrase" > /crypt-ramfs/passphrase
done
'';
preLVM = filterAttrs (n: v: v.preLVM) luks.devices;
postLVM = filterAttrs (n: v: !v.preLVM) luks.devices;
stage1Crypttab = pkgs.writeText "initrd-crypttab" (lib.concatStringsSep "\n" (lib.mapAttrsToList (n: v: let
opts = v.crypttabExtraOpts
++ optional v.allowDiscards "discard"
++ optionals v.bypassWorkqueues [ "no-read-workqueue" "no-write-workqueue" ]
++ optional (v.header != null) "header=${v.header}"
++ optional (v.keyFileOffset != null) "keyfile-offset=${toString v.keyFileOffset}"
++ optional (v.keyFileSize != null) "keyfile-size=${toString v.keyFileSize}"
++ optional (v.keyFileTimeout != null) "keyfile-timeout=${builtins.toString v.keyFileTimeout}s"
++ optional (v.tryEmptyPassphrase) "try-empty-password=true"
;
in "${n} ${v.device} ${if v.keyFile == null then "-" else v.keyFile} ${lib.concatStringsSep "," opts}") luks.devices));
in
{
imports = [
(mkRemovedOptionModule [ "boot" "initrd" "luks" "enable" ] "")
];
options = {
boot.initrd.luks.mitigateDMAAttacks = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
Unless enabled, encryption keys can be easily recovered by an attacker with physical
access to any machine with PCMCIA, ExpressCard, ThunderBolt or FireWire port.
More information is available at <http://en.wikipedia.org/wiki/DMA_attack>.
This option blacklists FireWire drivers, but doesn't remove them. You can manually
load the drivers if you need to use a FireWire device, but don't forget to unload them!
'';
};
boot.initrd.luks.cryptoModules = mkOption {
type = types.listOf types.str;
default =
[ "aes" "aes_generic" "blowfish" "twofish"
"serpent" "cbc" "xts" "lrw" "sha1" "sha256" "sha512"
"af_alg" "algif_skcipher"
];
description = lib.mdDoc ''
A list of cryptographic kernel modules needed to decrypt the root device(s).
The default includes all common modules.
'';
};
boot.initrd.luks.forceLuksSupportInInitrd = mkOption {
type = types.bool;
default = false;
internal = true;
description = lib.mdDoc ''
Whether to configure luks support in the initrd, when no luks
devices are configured.
'';
};
boot.initrd.luks.reusePassphrases = mkOption {
type = types.bool;
default = true;
description = lib.mdDoc ''
When opening a new LUKS device try reusing last successful
passphrase.
Useful for mounting a number of devices that use the same
passphrase without retyping it several times.
Such setup can be useful if you use {command}`cryptsetup luksSuspend`.
Different LUKS devices will still have
different master keys even when using the same passphrase.
'';
};
boot.initrd.luks.devices = mkOption {
default = { };
example = { luksroot.device = "/dev/disk/by-uuid/430e9eff-d852-4f68-aa3b-2fa3599ebe08"; };
description = lib.mdDoc ''
The encrypted disk that should be opened before the root
filesystem is mounted. Both LVM-over-LUKS and LUKS-over-LVM
setups are supported. The unencrypted devices can be accessed as
{file}`/dev/mapper/«name»`.
'';
type = with types; attrsOf (submodule (
{ name, ... }: { options = {
name = mkOption {
visible = false;
default = name;
example = "luksroot";
type = types.str;
description = lib.mdDoc "Name of the unencrypted device in {file}`/dev/mapper`.";
};
device = mkOption {
example = "/dev/disk/by-uuid/430e9eff-d852-4f68-aa3b-2fa3599ebe08";
type = types.str;
description = lib.mdDoc "Path of the underlying encrypted block device.";
};
header = mkOption {
default = null;
example = "/root/header.img";
type = types.nullOr types.str;
description = lib.mdDoc ''
The name of the file or block device that
should be used as header for the encrypted device.
'';
};
keyFile = mkOption {
default = null;
example = "/dev/sdb1";
type = types.nullOr types.str;
description = lib.mdDoc ''
The name of the file (can be a raw device or a partition) that
should be used as the decryption key for the encrypted device. If
not specified, you will be prompted for a passphrase instead.
'';
};
tryEmptyPassphrase = mkOption {
default = false;
type = types.bool;
description = lib.mdDoc ''
If keyFile fails then try an empty passphrase first before
prompting for password.
'';
};
keyFileTimeout = mkOption {
default = null;
example = 5;
type = types.nullOr types.int;
description = lib.mdDoc ''
The amount of time in seconds for a keyFile to appear before
timing out and trying passwords.
'';
};
keyFileSize = mkOption {
default = null;
example = 4096;
type = types.nullOr types.int;
description = lib.mdDoc ''
The size of the key file. Use this if only the beginning of the
key file should be used as a key (often the case if a raw device
or partition is used as key file). If not specified, the whole
`keyFile` will be used decryption, instead of just
the first `keyFileSize` bytes.
'';
};
keyFileOffset = mkOption {
default = null;
example = 4096;
type = types.nullOr types.int;
description = lib.mdDoc ''
The offset of the key file. Use this in combination with
`keyFileSize` to use part of a file as key file
(often the case if a raw device or partition is used as a key file).
If not specified, the key begins at the first byte of
`keyFile`.
'';
};
# FIXME: get rid of this option.
preLVM = mkOption {
default = true;
type = types.bool;
description = lib.mdDoc "Whether the luksOpen will be attempted before LVM scan or after it.";
};
allowDiscards = mkOption {
default = false;
type = types.bool;
description = lib.mdDoc ''
Whether to allow TRIM requests to the underlying device. This option
has security implications; please read the LUKS documentation before
activating it.
This option is incompatible with authenticated encryption (dm-crypt
stacked over dm-integrity).
'';
};
bypassWorkqueues = mkOption {
default = false;
type = types.bool;
description = lib.mdDoc ''
Whether to bypass dm-crypt's internal read and write workqueues.
Enabling this should improve performance on SSDs; see
[here](https://wiki.archlinux.org/index.php/Dm-crypt/Specialties#Disable_workqueue_for_increased_solid_state_drive_(SSD)_performance)
for more information. Needs Linux 5.9 or later.
'';
};
fallbackToPassword = mkOption {
default = false;
type = types.bool;
description = lib.mdDoc ''
Whether to fallback to interactive passphrase prompt if the keyfile
cannot be found. This will prevent unattended boot should the keyfile
go missing.
'';
};
gpgCard = mkOption {
default = null;
description = lib.mdDoc ''
The option to use this LUKS device with a GPG encrypted luks password by the GPG Smartcard.
If null (the default), GPG-Smartcard will be disabled for this device.
'';
type = with types; nullOr (submodule {
options = {
gracePeriod = mkOption {
default = 10;
type = types.int;
description = lib.mdDoc "Time in seconds to wait for the GPG Smartcard.";
};
encryptedPass = mkOption {
type = types.path;
description = lib.mdDoc "Path to the GPG encrypted passphrase.";
};
publicKey = mkOption {
type = types.path;
description = lib.mdDoc "Path to the Public Key.";
};
};
});
};
fido2 = {
credential = mkOption {
default = null;
example = "f1d00200d8dc783f7fb1e10ace8da27f8312d72692abfca2f7e4960a73f48e82e1f7571f6ebfcee9fb434f9886ccc8fcc52a6614d8d2";
type = types.nullOr types.str;
description = lib.mdDoc "The FIDO2 credential ID.";
};
credentials = mkOption {
default = [];
example = [ "f1d00200d8dc783f7fb1e10ace8da27f8312d72692abfca2f7e4960a73f48e82e1f7571f6ebfcee9fb434f9886ccc8fcc52a6614d8d2" ];
type = types.listOf types.str;
description = lib.mdDoc ''
List of FIDO2 credential IDs.
Use this if you have multiple FIDO2 keys you want to use for the same luks device.
'';
};
gracePeriod = mkOption {
default = 10;
type = types.int;
description = lib.mdDoc "Time in seconds to wait for the FIDO2 key.";
};
passwordLess = mkOption {
default = false;
type = types.bool;
description = lib.mdDoc ''
Defines whatever to use an empty string as a default salt.
Enable only when your device is PIN protected, such as [Trezor](https://trezor.io/).
'';
};
};
yubikey = mkOption {
default = null;
description = lib.mdDoc ''
The options to use for this LUKS device in YubiKey-PBA.
If null (the default), YubiKey-PBA will be disabled for this device.
'';
type = with types; nullOr (submodule {
options = {
twoFactor = mkOption {
default = true;
type = types.bool;
description = lib.mdDoc "Whether to use a passphrase and a YubiKey (true), or only a YubiKey (false).";
};
slot = mkOption {
default = 2;
type = types.int;
description = lib.mdDoc "Which slot on the YubiKey to challenge.";
};
saltLength = mkOption {
default = 16;
type = types.int;
description = lib.mdDoc "Length of the new salt in byte (64 is the effective maximum).";
};
keyLength = mkOption {
default = 64;
type = types.int;
description = lib.mdDoc "Length of the LUKS slot key derived with PBKDF2 in byte.";
};
iterationStep = mkOption {
default = 0;
type = types.int;
description = lib.mdDoc "How much the iteration count for PBKDF2 is increased at each successful authentication.";
};
gracePeriod = mkOption {
default = 10;
type = types.int;
description = lib.mdDoc "Time in seconds to wait for the YubiKey.";
};
/* TODO: Add to the documentation of the current module:
Options related to the storing the salt.
*/
storage = {
device = mkOption {
default = "/dev/sda1";
type = types.path;
description = lib.mdDoc ''
An unencrypted device that will temporarily be mounted in stage-1.
Must contain the current salt to create the challenge for this LUKS device.
'';
};
fsType = mkOption {
default = "vfat";
type = types.str;
description = lib.mdDoc "The filesystem of the unencrypted device.";
};
path = mkOption {
default = "/crypt-storage/default";
type = types.str;
description = lib.mdDoc ''
Absolute path of the salt on the unencrypted device with
that device's root directory as "/".
'';
};
};
};
});
};
preOpenCommands = mkOption {
type = types.lines;
default = "";
example = ''
mkdir -p /tmp/persistent
mount -t zfs rpool/safe/persistent /tmp/persistent
'';
description = lib.mdDoc ''
Commands that should be run right before we try to mount our LUKS device.
This can be useful, if the keys needed to open the drive is on another partition.
'';
};
postOpenCommands = mkOption {
type = types.lines;
default = "";
example = ''
umount /tmp/persistent
'';
description = lib.mdDoc ''
Commands that should be run right after we have mounted our LUKS device.
'';
};
crypttabExtraOpts = mkOption {
type = with types; listOf singleLineStr;
default = [];
example = [ "_netdev" ];
visible = false;
description = lib.mdDoc ''
Only used with systemd stage 1.
Extra options to append to the last column of the generated crypttab file.
'';
};
};
}));
};
boot.initrd.luks.gpgSupport = mkOption {
default = false;
type = types.bool;
description = lib.mdDoc ''
Enables support for authenticating with a GPG encrypted password.
'';
};
boot.initrd.luks.yubikeySupport = mkOption {
default = false;
type = types.bool;
description = lib.mdDoc ''
Enables support for authenticating with a YubiKey on LUKS devices.
See the NixOS wiki for information on how to properly setup a LUKS device
and a YubiKey to work with this feature.
'';
};
boot.initrd.luks.fido2Support = mkOption {
default = false;
type = types.bool;
description = lib.mdDoc ''
Enables support for authenticating with FIDO2 devices.
'';
};
};
config = mkIf (luks.devices != {} || luks.forceLuksSupportInInitrd) {
assertions =
[ { assertion = !(luks.gpgSupport && luks.yubikeySupport);
message = "YubiKey and GPG Card may not be used at the same time.";
}
{ assertion = !(luks.gpgSupport && luks.fido2Support);
message = "FIDO2 and GPG Card may not be used at the same time.";
}
{ assertion = !(luks.fido2Support && luks.yubikeySupport);
message = "FIDO2 and YubiKey may not be used at the same time.";
}
{ assertion = any (dev: dev.bypassWorkqueues) (attrValues luks.devices)
-> versionAtLeast kernelPackages.kernel.version "5.9";
message = "boot.initrd.luks.devices.<name>.bypassWorkqueues is not supported for kernels older than 5.9";
}
{ assertion = !config.boot.initrd.systemd.enable -> all (x: x.keyFileTimeout == null) (attrValues luks.devices);
message = "boot.initrd.luks.devices.<name>.keyFileTimeout is only supported for systemd initrd";
}
{ assertion = config.boot.initrd.systemd.enable -> all (dev: !dev.fallbackToPassword) (attrValues luks.devices);
message = "boot.initrd.luks.devices.<name>.fallbackToPassword is implied by systemd stage 1.";
}
{ assertion = config.boot.initrd.systemd.enable -> all (dev: dev.preLVM) (attrValues luks.devices);
message = "boot.initrd.luks.devices.<name>.preLVM is not used by systemd stage 1.";
}
{ assertion = config.boot.initrd.systemd.enable -> options.boot.initrd.luks.reusePassphrases.highestPrio == defaultPrio;
message = "boot.initrd.luks.reusePassphrases has no effect with systemd stage 1.";
}
{ assertion = config.boot.initrd.systemd.enable -> all (dev: dev.preOpenCommands == "" && dev.postOpenCommands == "") (attrValues luks.devices);
message = "boot.initrd.luks.devices.<name>.preOpenCommands and postOpenCommands is not supported by systemd stage 1. Please bind a service to cryptsetup.target or cryptsetup-pre.target instead.";
}
# TODO
{ assertion = config.boot.initrd.systemd.enable -> !luks.gpgSupport;
message = "systemd stage 1 does not support GPG smartcards yet.";
}
{ assertion = config.boot.initrd.systemd.enable -> !luks.fido2Support;
message = ''
systemd stage 1 does not support configuring FIDO2 unlocking through `boot.initrd.luks.devices.<name>.fido2`.
Use systemd-cryptenroll(1) to configure FIDO2 support.
'';
}
# TODO
{ assertion = config.boot.initrd.systemd.enable -> !luks.yubikeySupport;
message = "systemd stage 1 does not support Yubikeys yet.";
}
];
# actually, sbp2 driver is the one enabling the DMA attack, but this needs to be tested
boot.blacklistedKernelModules = optionals luks.mitigateDMAAttacks
["firewire_ohci" "firewire_core" "firewire_sbp2"];
# Some modules that may be needed for mounting anything ciphered
boot.initrd.availableKernelModules = [ "dm_mod" "dm_crypt" "cryptd" "input_leds" ]
++ luks.cryptoModules
# workaround until https://marc.info/?l=linux-crypto-vger&m=148783562211457&w=4 is merged
# remove once 'modprobe --show-depends xts' shows ecb as a dependency
++ (optional (builtins.elem "xts" luks.cryptoModules) "ecb");
# copy the cryptsetup binary and it's dependencies
boot.initrd.extraUtilsCommands = let
pbkdf2-sha512 = pkgs.runCommandCC "pbkdf2-sha512" { buildInputs = [ pkgs.openssl ]; } ''
mkdir -p "$out/bin"
cc -O3 -lcrypto ${./pbkdf2-sha512.c} -o "$out/bin/pbkdf2-sha512"
strip -s "$out/bin/pbkdf2-sha512"
'';
in
mkIf (!config.boot.initrd.systemd.enable) ''
copy_bin_and_libs ${pkgs.cryptsetup}/bin/cryptsetup