481 lines
16 KiB
Nix
481 lines
16 KiB
Nix
{ config, lib, pkgs, ... }:
|
|
|
|
with lib;
|
|
|
|
let
|
|
luks = config.boot.initrd.luks;
|
|
|
|
openCommand = name': { name, device, header, keyFile, keyFileSize, allowDiscards, yubikey, ... }: assert name' == name; ''
|
|
|
|
# Wait for a target (e.g. device, keyFile, header, ...) to appear.
|
|
wait_target() {
|
|
local name="$1"
|
|
local target="$2"
|
|
|
|
if [ ! -e $target ]; then
|
|
echo -n "Waiting 10 seconds for $name $target to appear"
|
|
local success=false;
|
|
for try in $(seq 10); do
|
|
echo -n "."
|
|
sleep 1
|
|
if [ -e $target ]; then success=true break; fi
|
|
done
|
|
if [ $success = true ]; then
|
|
echo " - success";
|
|
else
|
|
echo " - failure";
|
|
fi
|
|
fi
|
|
}
|
|
|
|
# Wait for luksRoot (and optionally keyFile and/or header) to appear, e.g.
|
|
# if on a USB drive.
|
|
wait_target "device" ${device}
|
|
|
|
${optionalString (keyFile != null) ''
|
|
wait_target "key file" ${keyFile}
|
|
''}
|
|
|
|
${optionalString (header != null) ''
|
|
wait_target "header" ${header}
|
|
''}
|
|
|
|
open_normally() {
|
|
echo luksOpen ${device} ${name} ${optionalString allowDiscards "--allow-discards"} \
|
|
${optionalString (header != null) "--header=${header}"} \
|
|
${optionalString (keyFile != null) "--key-file=${keyFile} ${optionalString (keyFileSize != null) "--keyfile-size=${toString keyFileSize}"}"} \
|
|
> /.luksopen_args
|
|
cryptsetup-askpass
|
|
rm /.luksopen_args
|
|
}
|
|
|
|
${optionalString (luks.yubikeySupport && (yubikey != null)) ''
|
|
|
|
rbtohex() {
|
|
( od -An -vtx1 | tr -d ' \n' )
|
|
}
|
|
|
|
hextorb() {
|
|
( tr '[:lower:]' '[:upper:]' | sed -e 's/\([0-9A-F]\{2\}\)/\\\\\\x\1/gI' | xargs printf )
|
|
}
|
|
|
|
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
|
|
|
|
mkdir -p ${yubikey.storage.mountPoint}
|
|
mount -t ${yubikey.storage.fsType} ${toString yubikey.storage.device} ${yubikey.storage.mountPoint}
|
|
|
|
salt="$(cat ${yubikey.storage.mountPoint}${yubikey.storage.path} | sed -n 1p | tr -d '\n')"
|
|
iterations="$(cat ${yubikey.storage.mountPoint}${yubikey.storage.path} | sed -n 2p | tr -d '\n')"
|
|
challenge="$(echo -n $salt | openssl-wrap dgst -binary -sha512 | rbtohex)"
|
|
response="$(ykchalresp -${toString yubikey.slot} -x $challenge 2>/dev/null)"
|
|
|
|
for try in $(seq 3); do
|
|
|
|
${optionalString yubikey.twoFactor ''
|
|
echo -n "Enter two-factor passphrase: "
|
|
read -s k_user
|
|
echo
|
|
''}
|
|
|
|
if [ ! -z "$k_user" ]; then
|
|
k_luks="$(echo -n $k_user | pbkdf2-sha512 ${toString yubikey.keyLength} $iterations $response | rbtohex)"
|
|
else
|
|
k_luks="$(echo | pbkdf2-sha512 ${toString yubikey.keyLength} $iterations $response | rbtohex)"
|
|
fi
|
|
|
|
echo -n "$k_luks" | hextorb | cryptsetup luksOpen ${device} ${name} ${optionalString allowDiscards "--allow-discards"} --key-file=-
|
|
|
|
if [ $? == "0" ]; then
|
|
opened=true
|
|
break
|
|
else
|
|
opened=false
|
|
echo "Authentication failed!"
|
|
fi
|
|
done
|
|
|
|
if [ "$opened" == false ]; then
|
|
umount ${yubikey.storage.mountPoint}
|
|
echo "Maximum authentication errors reached"
|
|
exit 1
|
|
fi
|
|
|
|
echo -n "Gathering entropy for new salt (please enter random keys to generate entropy if this blocks for long)..."
|
|
for i in $(seq ${toString yubikey.saltLength}); do
|
|
byte="$(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"
|
|
${optionalString (yubikey.iterationStep > 0) ''
|
|
new_iterations="$(($new_iterations + ${toString yubikey.iterationStep}))"
|
|
''}
|
|
|
|
new_challenge="$(echo -n $new_salt | openssl-wrap dgst -binary -sha512 | rbtohex)"
|
|
|
|
new_response="$(ykchalresp -${toString yubikey.slot} -x $new_challenge 2>/dev/null)"
|
|
|
|
if [ ! -z "$k_user" ]; then
|
|
new_k_luks="$(echo -n $k_user | pbkdf2-sha512 ${toString yubikey.keyLength} $new_iterations $new_response | rbtohex)"
|
|
else
|
|
new_k_luks="$(echo | pbkdf2-sha512 ${toString yubikey.keyLength} $new_iterations $new_response | rbtohex)"
|
|
fi
|
|
|
|
mkdir -p ${yubikey.ramfsMountPoint}
|
|
# 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!
|
|
mount -t ramfs none ${yubikey.ramfsMountPoint}
|
|
|
|
echo -n "$new_k_luks" | hextorb > ${yubikey.ramfsMountPoint}/new_key
|
|
echo -n "$k_luks" | hextorb | cryptsetup luksChangeKey ${device} --key-file=- ${yubikey.ramfsMountPoint}/new_key
|
|
|
|
if [ $? == "0" ]; then
|
|
echo -ne "$new_salt\n$new_iterations" > ${yubikey.storage.mountPoint}${yubikey.storage.path}
|
|
else
|
|
echo "Warning: Could not update LUKS key, current challenge persists!"
|
|
fi
|
|
|
|
rm -f ${yubikey.ramfsMountPoint}/new_key
|
|
umount ${yubikey.ramfsMountPoint}
|
|
rm -rf ${yubikey.ramfsMountPoint}
|
|
|
|
umount ${yubikey.storage.mountPoint}
|
|
}
|
|
|
|
${optionalString (yubikey.gracePeriod > 0) ''
|
|
echo -n "Waiting ${toString yubikey.gracePeriod} seconds as grace..."
|
|
for i in $(seq ${toString yubikey.gracePeriod}); do
|
|
sleep 1
|
|
echo -n .
|
|
done
|
|
echo "ok"
|
|
''}
|
|
|
|
yubikey_missing=true
|
|
ykinfo -v 1>/dev/null 2>&1
|
|
if [ $? != "0" ]; then
|
|
echo -n "waiting 10 seconds for yubikey to appear..."
|
|
for try in $(seq 10); do
|
|
sleep 1
|
|
ykinfo -v 1>/dev/null 2>&1
|
|
if [ $? == "0" ]; then
|
|
yubikey_missing=false
|
|
break
|
|
fi
|
|
echo -n .
|
|
done
|
|
echo "ok"
|
|
else
|
|
yubikey_missing=false
|
|
fi
|
|
|
|
if [ "$yubikey_missing" == true ]; then
|
|
echo "no yubikey found, falling back to non-yubikey open procedure"
|
|
open_normally
|
|
else
|
|
open_yubikey
|
|
fi
|
|
''}
|
|
|
|
# open luksRoot and scan for logical volumes
|
|
${optionalString ((!luks.yubikeySupport) || (yubikey == null)) ''
|
|
open_normally
|
|
''}
|
|
'';
|
|
|
|
preLVM = filterAttrs (n: v: v.preLVM) luks.devices;
|
|
postLVM = filterAttrs (n: v: !v.preLVM) luks.devices;
|
|
|
|
in
|
|
{
|
|
|
|
options = {
|
|
|
|
boot.initrd.luks.mitigateDMAAttacks = mkOption {
|
|
type = types.bool;
|
|
default = true;
|
|
description = ''
|
|
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 <link xlink:href="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"
|
|
(if pkgs.stdenv.system == "x86_64-linux" then "aes_x86_64" else "aes_i586")
|
|
];
|
|
description = ''
|
|
A list of cryptographic kernel modules needed to decrypt the root device(s).
|
|
The default includes all common modules.
|
|
'';
|
|
};
|
|
|
|
boot.initrd.luks.devices = mkOption {
|
|
default = { };
|
|
example = { "luksroot".device = "/dev/disk/by-uuid/430e9eff-d852-4f68-aa3b-2fa3599ebe08"; };
|
|
description = ''
|
|
The encrypted disk that should be opened before the root
|
|
filesystem is mounted. Both LVM-over-LUKS and LUKS-over-LVM
|
|
setups are sypported. The unencrypted devices can be accessed as
|
|
<filename>/dev/mapper/<replaceable>name</replaceable></filename>.
|
|
'';
|
|
|
|
type = with types; loaOf (submodule (
|
|
{ name, ... }: { options = {
|
|
|
|
name = mkOption {
|
|
visible = false;
|
|
default = name;
|
|
example = "luksroot";
|
|
type = types.str;
|
|
description = "Name of the unencrypted device in <filename>/dev/mapper</filename>.";
|
|
};
|
|
|
|
device = mkOption {
|
|
example = "/dev/disk/by-uuid/430e9eff-d852-4f68-aa3b-2fa3599ebe08";
|
|
type = types.str;
|
|
description = "Path of the underlying encrypted block device.";
|
|
};
|
|
|
|
header = mkOption {
|
|
default = null;
|
|
example = "/root/header.img";
|
|
type = types.nullOr types.str;
|
|
description = ''
|
|
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 = ''
|
|
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.
|
|
'';
|
|
};
|
|
|
|
keyFileSize = mkOption {
|
|
default = null;
|
|
example = 4096;
|
|
type = types.nullOr types.int;
|
|
description = ''
|
|
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
|
|
<literal>keyFile</literal> will be used decryption, instead of just
|
|
the first <literal>keyFileSize</literal> bytes.
|
|
'';
|
|
};
|
|
|
|
# FIXME: get rid of this option.
|
|
preLVM = mkOption {
|
|
default = true;
|
|
type = types.bool;
|
|
description = "Whether the luksOpen will be attempted before LVM scan or after it.";
|
|
};
|
|
|
|
allowDiscards = mkOption {
|
|
default = false;
|
|
type = types.bool;
|
|
description = ''
|
|
Whether to allow TRIM requests to the underlying device. This option
|
|
has security implications; please read the LUKS documentation before
|
|
activating it.
|
|
'';
|
|
};
|
|
|
|
yubikey = mkOption {
|
|
default = null;
|
|
description = ''
|
|
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 = "Whether to use a passphrase and a Yubikey (true), or only a Yubikey (false).";
|
|
};
|
|
|
|
slot = mkOption {
|
|
default = 2;
|
|
type = types.int;
|
|
description = "Which slot on the Yubikey to challenge.";
|
|
};
|
|
|
|
saltLength = mkOption {
|
|
default = 16;
|
|
type = types.int;
|
|
description = "Length of the new salt in byte (64 is the effective maximum).";
|
|
};
|
|
|
|
keyLength = mkOption {
|
|
default = 64;
|
|
type = types.int;
|
|
description = "Length of the LUKS slot key derived with PBKDF2 in byte.";
|
|
};
|
|
|
|
iterationStep = mkOption {
|
|
default = 0;
|
|
type = types.int;
|
|
description = "How much the iteration count for PBKDF2 is increased at each successful authentication.";
|
|
};
|
|
|
|
gracePeriod = mkOption {
|
|
default = 2;
|
|
type = types.int;
|
|
description = "Time in seconds to wait before attempting to find the Yubikey.";
|
|
};
|
|
|
|
ramfsMountPoint = mkOption {
|
|
default = "/crypt-ramfs";
|
|
type = types.str;
|
|
description = "Path where the ramfs used to update the LUKS key will be mounted during early boot.";
|
|
};
|
|
|
|
/* 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 = ''
|
|
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 = "The filesystem of the unencrypted device.";
|
|
};
|
|
|
|
mountPoint = mkOption {
|
|
default = "/crypt-storage";
|
|
type = types.str;
|
|
description = "Path where the unencrypted device will be mounted during early boot.";
|
|
};
|
|
|
|
path = mkOption {
|
|
default = "/crypt-storage/default";
|
|
type = types.str;
|
|
description = ''
|
|
Absolute path of the salt on the unencrypted device with
|
|
that device's root directory as "/".
|
|
'';
|
|
};
|
|
};
|
|
};
|
|
});
|
|
};
|
|
|
|
}; }));
|
|
};
|
|
|
|
boot.initrd.luks.yubikeySupport = mkOption {
|
|
default = false;
|
|
type = types.bool;
|
|
description = ''
|
|
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.
|
|
'';
|
|
};
|
|
};
|
|
|
|
config = mkIf (luks.devices != {}) {
|
|
|
|
# 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" ] ++ luks.cryptoModules;
|
|
|
|
# copy the cryptsetup binary and it's dependencies
|
|
boot.initrd.extraUtilsCommands = ''
|
|
copy_bin_and_libs ${pkgs.cryptsetup}/bin/cryptsetup
|
|
|
|
cat > $out/bin/cryptsetup-askpass <<EOF
|
|
#!$out/bin/sh -e
|
|
if [ -e /.luksopen_args ]; then
|
|
cryptsetup \$(cat /.luksopen_args)
|
|
killall -q cryptsetup
|
|
else
|
|
echo "Passphrase is not requested now"
|
|
exit 1
|
|
fi
|
|
EOF
|
|
chmod +x $out/bin/cryptsetup-askpass
|
|
|
|
${optionalString luks.yubikeySupport ''
|
|
copy_bin_and_libs ${pkgs.yubikey-personalization}/bin/ykchalresp
|
|
copy_bin_and_libs ${pkgs.yubikey-personalization}/bin/ykinfo
|
|
copy_bin_and_libs ${pkgs.openssl.bin}/bin/openssl
|
|
|
|
cc -O3 -I${pkgs.openssl.dev}/include -L${pkgs.openssl.out}/lib ${./pbkdf2-sha512.c} -o pbkdf2-sha512 -lcrypto
|
|
strip -s pbkdf2-sha512
|
|
copy_bin_and_libs pbkdf2-sha512
|
|
|
|
mkdir -p $out/etc/ssl
|
|
cp -pdv ${pkgs.openssl.out}/etc/ssl/openssl.cnf $out/etc/ssl
|
|
|
|
cat > $out/bin/openssl-wrap <<EOF
|
|
#!$out/bin/sh
|
|
export OPENSSL_CONF=$out/etc/ssl/openssl.cnf
|
|
$out/bin/openssl "\$@"
|
|
EOF
|
|
chmod +x $out/bin/openssl-wrap
|
|
''}
|
|
'';
|
|
|
|
boot.initrd.extraUtilsCommandsTest = ''
|
|
$out/bin/cryptsetup --version
|
|
${optionalString luks.yubikeySupport ''
|
|
$out/bin/ykchalresp -V
|
|
$out/bin/ykinfo -V
|
|
$out/bin/openssl-wrap version
|
|
''}
|
|
'';
|
|
|
|
boot.initrd.preLVMCommands = concatStrings (mapAttrsToList openCommand preLVM);
|
|
boot.initrd.postDeviceCommands = concatStrings (mapAttrsToList openCommand postLVM);
|
|
|
|
environment.systemPackages = [ pkgs.cryptsetup ];
|
|
};
|
|
}
|