diff options
Diffstat (limited to 'nixos/modules/system/boot/luksroot.nix')
| -rw-r--r-- | nixos/modules/system/boot/luksroot.nix | 143 |
1 files changed, 94 insertions, 49 deletions
diff --git a/nixos/modules/system/boot/luksroot.nix b/nixos/modules/system/boot/luksroot.nix index d70d1341166..117c526fcd3 100644 --- a/nixos/modules/system/boot/luksroot.nix +++ b/nixos/modules/system/boot/luksroot.nix @@ -43,22 +43,33 @@ let } hextorb() { - ( tr '[:lower:]' '[:upper:]' | sed -e 's/\([0-9A-F]\{2\}\)/\\\\\\x\1/gI'| xargs printf ) + ( tr '[:lower:]' '[:upper:]' | sed -e 's/\([0-9A-F]\{2\}\)/\\\\\\x\1/gI' | xargs printf ) } open_yubikey() { - mkdir -p ${yubikey.storage.mountPoint} - mount -t ${yubikey.storage.fsType} ${toString yubikey.storage.device} ${yubikey.storage.mountPoint} - - local uuid_r + # 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 - sleep 1 + mkdir -p ${yubikey.storage.mountPoint} + mount -t ${yubikey.storage.fsType} ${toString yubikey.storage.device} ${yubikey.storage.mountPoint} - uuid_r="$(cat ${yubikey.storage.mountPoint}${yubikey.storage.path})" + 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 $(seq 3); do @@ -68,9 +79,11 @@ let echo ''} - challenge="$(echo -n $k_user$uuid_r | openssl-wrap dgst -binary -sha512 | rbtohex)" - - k_luks="$(ykchalresp -${toString yubikey.slot} -x $challenge 2>/dev/null)" + if [ ! -z "$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} ${optionalString allowDiscards "--allow-discards"} --key-file=- @@ -89,53 +102,60 @@ let exit 1 fi - update_failed=false - - local new_uuid_r - new_uuid_r="$(uuidgen)" - if [ $? != "0" ]; then - for try in $(seq 10); do - sleep 1 - new_uuid_r="$(uuidgen)" - if [ $? == "0" ]; then break; fi - if [ $try -eq 10 ]; then update_failed=true; fi - done - 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" - if [ "$update_failed" == false ]; then - new_uuid_r="$(echo -n $new_uuid_r | head -c 36 | tr -d '-')" + new_iterations="$iterations" + ${optionalString (yubikey.iterationStep > 0) '' + new_iterations="$(($new_iterations + ${toString yubikey.iterationStep}))" + ''} - local new_challenge - new_challenge="$(echo -n $k_user$new_uuid_r | openssl-wrap dgst -binary -sha512 | rbtohex)" + new_challenge="$(echo -n $new_salt | openssl-wrap dgst -binary -sha512 | rbtohex)" - local new_k_luks - new_k_luks="$(ykchalresp -${toString yubikey.slot} -x $new_challenge 2>/dev/null)" + new_response="$(ykchalresp -${toString yubikey.slot} -x $new_challenge 2>/dev/null)" - 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 ${yubikey.ramfsMountPoint} + if [ ! -z "$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 > ${yubikey.ramfsMountPoint}/new_key - echo -n "$k_luks" | cryptsetup luksChangeKey ${device} --key-file=- ${yubikey.ramfsMountPoint}/new_key + 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} - if [ $? == "0" ]; then - echo -n "$new_uuid_r" > ${yubikey.storage.mountPoint}${yubikey.storage.path} - else - echo "Warning: Could not update LUKS key, current challenge persists!" - fi + echo -n "$new_k_luks" | hextorb > ${yubikey.ramfsMountPoint}/new_key + echo -n "$k_luks" | hextorb | cryptsetup luksChangeKey ${device} --key-file=- ${yubikey.ramfsMountPoint}/new_key - rm -f ${yubikey.ramfsMountPoint}/new_key - umount ${yubikey.ramfsMountPoint} - rm -rf ${yubikey.ramfsMountPoint} + if [ $? == "0" ]; then + echo -ne "$new_salt\n$new_iterations" > ${yubikey.storage.mountPoint}${yubikey.storage.path} else - echo "Warning: Could not obtain new UUID, current challenge persists!" + 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 @@ -292,6 +312,30 @@ in 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.string; @@ -300,7 +344,7 @@ in storage = mkOption { type = types.optionSet; - description = "Options related to the storing the random UUID"; + description = "Options related to the storing the salt"; options = { device = mkOption { @@ -308,7 +352,7 @@ in type = types.path; description = '' An unencrypted device that will temporarily be mounted in stage-1. - Must contain the current random UUID to create the challenge for this LUKS device. + Must contain the current salt to create the challenge for this LUKS device. ''; }; @@ -328,7 +372,7 @@ in default = "/crypt-storage/default"; type = types.string; description = '' - Absolute path of the random UUID on the unencrypted device with + Absolute path of the salt on the unencrypted device with that device's root directory as "/". ''; }; @@ -370,11 +414,13 @@ in cp -pdv ${pkgs.popt}/lib/libpopt*.so.* $out/lib ${optionalString luks.yubikeySupport '' - cp -pdv ${pkgs.utillinux}/bin/uuidgen $out/bin cp -pdv ${pkgs.ykpers}/bin/ykchalresp $out/bin cp -pdv ${pkgs.ykpers}/bin/ykinfo $out/bin cp -pdv ${pkgs.openssl}/bin/openssl $out/bin + cc -O3 -I${pkgs.openssl}/include -L${pkgs.openssl}/lib ${./pbkdf2-sha512.c} -o $out/bin/pbkdf2-sha512 -lcrypto + strip -s $out/bin/pbkdf2-sha512 + cp -pdv ${pkgs.libusb1}/lib/libusb*.so.* $out/lib cp -pdv ${pkgs.ykpers}/lib/libykpers*.so.* $out/lib cp -pdv ${pkgs.libyubikey}/lib/libyubikey*.so.* $out/lib @@ -394,7 +440,6 @@ EOF boot.initrd.extraUtilsCommandsTest = '' $out/bin/cryptsetup --version ${optionalString luks.yubikeySupport '' - $out/bin/uuidgen --version $out/bin/ykchalresp -V $out/bin/ykinfo -V cat > $out/bin/openssl-wrap <<EOF |