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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-06-03 13:54:25 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-06-03 13:54:25 +0000 |
commit | 9cb1c4df7b9ce1a9ad1312621b0f2b16a94fba3a (patch) | |
tree | 2efb72864cc69e174c9c5ee33efb88a5f1553b48 /modules.d/97masterkey | |
parent | Initial commit. (diff) | |
download | dracut-9cb1c4df7b9ce1a9ad1312621b0f2b16a94fba3a.tar.xz dracut-9cb1c4df7b9ce1a9ad1312621b0f2b16a94fba3a.zip |
Adding upstream version 060+5.upstream/060+5
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'modules.d/97masterkey')
-rw-r--r-- | modules.d/97masterkey/README | 68 | ||||
-rwxr-xr-x | modules.d/97masterkey/masterkey.sh | 69 | ||||
-rwxr-xr-x | modules.d/97masterkey/module-setup.sh | 26 |
3 files changed, 163 insertions, 0 deletions
diff --git a/modules.d/97masterkey/README b/modules.d/97masterkey/README new file mode 100644 index 0000000..524ccfc --- /dev/null +++ b/modules.d/97masterkey/README @@ -0,0 +1,68 @@ +# Directions for creating the kernel master key that will be used for +# encrypting/decrypting other keys. + +# A trusted key is a TPM random number, which is only ever exposed to +# userspace as an encrypted datablob. A trusted key can be sealed to a +# set of PCR values. For more details on trusted keys, refer to the +# kernel keys-trusted-encrypted.txt documentation. +$ keyctl add trusted kmk-trusted "new 32" @u +801713097 + +# For those systems which don't have a TPM, but want to experiment with +# encrypted keys, create a user key of 32 random bytes. Unlike +# trusted/encrypted keys, user type key data is visible to userspace. +$ keyctl add user kmk-user "`dd if=/dev/urandom bs=1 count=32 2>/dev/null`" @u +144468621 + +# Save the kernel master key (trusted type): +$ su -c 'keyctl pipe `keyctl search @u trusted kmk-trusted` > /etc/keys/kmk-trusted.blob' + +# or (user type): +$ su -c 'keyctl pipe `keyctl search @u user kmk-user` > /etc/keys/kmk-user.blob' + +# A useful feature of trusted keys is that it is possible to prevent their +# unsealing at later time by providing the parameter 'pcrlock=<pcrnum>' when +# loading it, which causes the PCR #<pcrnum> to be extended with a random value. +# Actually, the <pcrnum> variable is set to '11' to let users experiment with +# this feature by using a register that is never extended during the boot, +# making the re-sealing not necessary. In the future, the kernel master key will +# be sealed to the PCR #14 which is extended, according to the TrustedGRUB +# documentation[1], to the measure of the kernel and the initial ramdisk. + +# The kernel master key path name and type can be set in one of the following +# ways (specified in the order in which variables are overwritten): + +1) use default values: +-------------------------------------------------------------------------- +MULTIKERNELMODE="NO" +MASTERKEYTYPE="trusted" +MASTERKEY="/etc/keys/kmk-${MASTERKEYTYPE}.blob" +-------------------------------------------------------------------------- + +2) create the configuration file '/etc/sysconfig/masterkey' to override the +value of one or all variables; + +3) specify these parameters in the kernel command line: +- masterkey=</kernel/master/key/path>, to override the MASTERKEY variable; +- masterkeytype=<kernel-master-key-type>, to override the MASTERKEYTYPE variable. + +# The variable MULTIKERNELMODE has been introduced to support multi boot +# configurations, where a trusted/user key is tied to a specific kernel and +# initial ramdisk. In this case, setting MULTIKERNELMODE to 'YES' will cause the +# kernel version to be added to the default masterkey path name, so that the +# MASTERKEY variable should not be overridden each time a different kernel is +# chosen. The default value of MASTERKEY will be equal to: +-------------------------------------------------------------------------- +MASTERKEY="/etc/keys/kmk-${MASTERKEYTYPE}-$(uname -r).blob" +-------------------------------------------------------------------------- + +# The masterkey path name also depends on the value of MASTERKEYTYPE, as reported +# in the default values for defined variables. For example, if only MASTERKEYTYPE +# is overridden by setting it to 'user' in the configuration file or from the +# kernel command line, the value of MASTERKEY will be: +-------------------------------------------------------------------------- +MASTERKEY="/etc/keys/kmk-user.blob" +-------------------------------------------------------------------------- + + +[1] https://projects.sirrix.com/trac/trustedgrub/ diff --git a/modules.d/97masterkey/masterkey.sh b/modules.d/97masterkey/masterkey.sh new file mode 100755 index 0000000..6dd6a4d --- /dev/null +++ b/modules.d/97masterkey/masterkey.sh @@ -0,0 +1,69 @@ +#!/bin/sh + +# Licensed under the GPLv2 +# +# Copyright (C) 2011 Politecnico di Torino, Italy +# TORSEC group -- http://security.polito.it +# Roberto Sassu <roberto.sassu@polito.it> + +MASTERKEYSCONFIG="${NEWROOT}/etc/sysconfig/masterkey" +MULTIKERNELMODE="NO" +PCRLOCKNUM=11 + +load_masterkey() { + # read the configuration from the config file + # shellcheck disable=SC1090 + [ -f "${MASTERKEYSCONFIG}" ] \ + && . "${MASTERKEYSCONFIG}" + + # override the kernel master key path name from the 'masterkey=' parameter + # in the kernel command line + MASTERKEYARG=$(getarg masterkey=) && MASTERKEY=${MASTERKEYARG} + + # override the kernel master key type from the 'masterkeytype=' parameter + # in the kernel command line + MASTERKEYTYPEARG=$(getarg masterkeytype=) && MASTERKEYTYPE=${MASTERKEYTYPEARG} + + # set default values + [ -z "${MASTERKEYTYPE}" ] \ + && MASTERKEYTYPE="trusted" + + if [ -z "${MASTERKEY}" ]; then + # append the kernel version to the default masterkey path name + # if MULTIKERNELMODE is set to YES + if [ "${MULTIKERNELMODE}" = "YES" ]; then + MASTERKEY="/etc/keys/kmk-${MASTERKEYTYPE}-$(uname -r).blob" + else + MASTERKEY="/etc/keys/kmk-${MASTERKEYTYPE}.blob" + fi + fi + + # set the kernel master key path name + MASTERKEYPATH="${NEWROOT}${MASTERKEY}" + + # check for kernel master key's existence + if [ ! -f "${MASTERKEYPATH}" ]; then + if [ "${RD_DEBUG}" = "yes" ]; then + info "masterkey: kernel master key file not found: ${MASTERKEYPATH}" + fi + return 1 + fi + + # read the kernel master key blob + read -r KEYBLOB < "${MASTERKEYPATH}" + + # add the 'load' prefix if the key type is 'trusted' + [ "${MASTERKEYTYPE}" = "trusted" ] \ + && KEYBLOB="load ${KEYBLOB} pcrlock=${PCRLOCKNUM}" + + # load the kernel master key + info "Loading the kernel master key" + keyctl add "${MASTERKEYTYPE}" "kmk-${MASTERKEYTYPE}" "${KEYBLOB}" @u > /dev/null || { + info "masterkey: failed to load the kernel master key: kmk-${MASTERKEYTYPE}" + return 1 + } + + return 0 +} + +load_masterkey diff --git a/modules.d/97masterkey/module-setup.sh b/modules.d/97masterkey/module-setup.sh new file mode 100755 index 0000000..49b006e --- /dev/null +++ b/modules.d/97masterkey/module-setup.sh @@ -0,0 +1,26 @@ +#!/bin/bash + +# called by dracut +check() { + [[ $hostonly ]] && { + require_binaries keyctl uname || return 1 + } + + return 255 +} + +# called by dracut +depends() { + return 0 +} + +# called by dracut +installkernel() { + instmods trusted encrypted +} + +# called by dracut +install() { + inst_multiple keyctl uname + inst_hook pre-pivot 60 "$moddir/masterkey.sh" +} |