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|
{ config, lib, pkgs, ... }:
with lib;
let
luks = config.boot.initrd.luks;
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
}
'';
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
# For Yubikey salt storage
mkdir -p /crypt-storage
# Disable all input echo for the whole stage. We could use read -s
# instead but that would ocasionally leak characters between read
# invocations.
stty -echo
'';
postCommands = ''
stty echo
umount /crypt-storage 2>/dev/null
umount /crypt-ramfs 2>/dev/null
'';
openCommand = name': { name, device, header, keyFile, keyFileSize, keyFileOffset, allowDiscards, yubikey, fallbackToPassword, ... }: assert name' == name;
let
csopen = "cryptsetup luksOpen ${device} ${name} ${optionalString allowDiscards "--allow-discards"} ${optionalString (header != null) "--header=${header}"}";
cschange = "cryptsetup luksChangeKey ${device} ${optionalString (header != null) "--header=${header}"}";
in ''
# Wait for luksRoot (and optionally keyFile and/or header) to appear, e.g.
# if on a USB drive.
wait_target "device" ${device} || die "${device} is unavailable"
${optionalString (header != null) ''
wait_target "header" ${header} || die "${header} is unavailable"
''}
do_open_passphrase() {
local passphrase
while true; do
echo -n "Passphrase for ${device}: "
passphrase=
while true; do
if [ -e /crypt-ramfs/passphrase ]; then
echo "reused"
passphrase=$(cat /crypt-ramfs/passphrase)
break
else
# ask cryptsetup-askpass
echo -n "${device}" > /crypt-ramfs/device
# and try reading it from /dev/console with a timeout
IFS= read -t 1 -r passphrase
if [ -n "$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 ${device}..."
echo -n "$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 (keyFile != null) then ''
if wait_target "key file" ${keyFile}; then
${csopen} --key-file=${keyFile} \
${optionalString (keyFileSize != null) "--keyfile-size=${toString keyFileSize}"} \
${optionalString (keyFileOffset != null) "--keyfile-offset=${toString keyFileOffset}"}
else
${if fallbackToPassword then "echo" else "die"} "${keyFile} is unavailable"
echo " - failing back to interactive password prompt"
do_open_passphrase
fi
'' else ''
do_open_passphrase
''}
}
${if luks.yubikeySupport && (yubikey != null) then ''
# 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 ${yubikey.storage.fsType} ${yubikey.storage.device} /crypt-storage || \
die "Failed to mount Yubikey salt storage device"
salt="$(cat /crypt-storage${yubikey.storage.path} | sed -n 1p | tr -d '\n')"
iterations="$(cat /crypt-storage${yubikey.storage.path} | sed -n 2p | tr -d '\n')"
challenge="$(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
${optionalString yubikey.twoFactor ''
echo -n "Enter two-factor passphrase: "
read -r k_user
echo
''}
if [ ! -z "$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 | ${csopen} --key-file=-
if [ $? == 0 ]; then
opened=true
break
else
opened=false
echo "Authentication failed!"
fi
done
[ "$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 ${toString yubikey.saltLength}); do
byte="$(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 $new_response | rbtohex)"
fi
echo -n "$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$new_iterations" > /crypt-storage${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_yubikey() {
if wait_yubikey ${toString yubikey.gracePeriod}; then
do_open_yubikey
else
echo "No yubikey found, falling back to non-yubikey open procedure"
open_normally
fi
}
open_yubikey
'' else ''
open_normally
''}
'';
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;
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.hostPlatform.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.forceLuksSupportInInitrd = mkOption {
type = types.bool;
default = false;
internal = true;
description = ''
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 = ''
When opening a n
|