Add PKCS#11 pin basic functionality

Signed-off-by: Sergio Arroutbi <[email protected]>
Co-authored-by: Sergio Correia <[email protected]>

.github/workflows/install-dependencies

@@ -23,8 +23,7 @@ debian:*|ubuntu:*)
     while ! apt-get -y install ${COMMON} \
         build-essential pkg-config libssl-dev libjansson-dev libjose-dev \
         luksmeta libluksmeta-dev libpwquality-tools libglib2.0-dev \
-        libudisks2-dev libaudit-dev systemd; do
-
+        libudisks2-dev libaudit-dev systemd opensc pcscd libsofthsm2-dev; do
         sleep 5
     done
     ;;
@@ -33,8 +32,10 @@ debian:*|ubuntu:*)
     printf 'max_parallel_downloads=10\nfastestmirror=1\n' >> /etc/dnf/dnf.conf
     dnf -y clean all
     dnf -y --setopt=deltarpm=0 update
-    dnf -y install dnf-utils jq socat cryptsetup keyutils cracklib-dicts lsof
-    command -v dnf5 && dnf5 -y install dnf5-command\(builddep\) || dnf -y install dnf-command\(builddep\)
+    dnf -y install dnf-utils jq socat cryptsetup keyutils cracklib-dicts lsof \
+        opensc pcsc-lite softhsm
+    command -v dnf5 && dnf5 -y install dnf5-command\(builddep\) \
+        || dnf -y install dnf-command\(builddep\)
     dnf -y builddep clevis
     ;;
 
@@ -48,7 +49,8 @@ debian:*|ubuntu:*)
     yum -y --allowerasing install ${COMMON}
     yum -y install pkgconfig openssl-devel openssl zlib-devel \
         jansson-devel findutils gcc libjose-devel luksmeta libluksmeta-devel \
-        audit-libs-devel tpm2-tools desktop-file-utils cracklib-dicts
+        audit-libs-devel tpm2-tools desktop-file-utils cracklib-dicts opensc \
+        pcsc-lite softhsm
     sed -i 's|>=1\.0\.2|>=1\.0\.1|' meson.build
     ;;
 esac

README.md

@@ -77,6 +77,102 @@ $ echo hi | clevis encrypt tpm2 '{}' > hi.jwe
 Clevis store the public and private keys of the encrypted key in the JWE object,
 so those can be fetched on decryption to unseal the key encrypted using the TPM2.
 
+#### PIN: PKCS#11
+
+Clevis can perform the role of a PKCS#11 application, as described in the [RFC 7512: The PKCS#11 URI Scheme](https://www.rfc-editor.org/rfc/rfc7512.html).
+
+PKCS#11 protocol determines that a PIN (Personal Identity Number) must be configured into the hardware device so that the unlocking process is successful. Clevis will allow users to unlock a particular encrypted disk, and will provide a way to get the PIN. There will be two possibilities:
+
+1 - Provide the PIN at boot time: In this first case, Clevis will detect PKCS#11 device and will prompt for its PIN.
+In case PIN is wrong, Clevis will prompt for the PIN again. It is the user's responsibility to be aware of the possible lock / brick of the device in case PIN is unknown.
+
+2 - Provide the PIN at Clevis configuration time: In this second case, Clevis will be configured with the PIN value.
+
+Initially, RFC7512 defines a mechanism to specify a special kind of URI (the `pkcs11` URI), that allows identifying both a device and also the information required for it to be unlocked. Special attention deserves the parameters `pin-value`, which allow specifying the value of the PIN or the location of the PIN respectively. Clevis will understand, initially, the 'pin-value' parameter. Below you can find and example of PKCS#11 URIs using previous parameter:
+
+* PKCS#11 URI with `pin-value` defined:
+
+```
+pkcs11:token=Software%20PKCS%2311%20softtoken;manufacturer=Snake%20Oil,%20Inc.?pin-value=the-pin
+```
+
+In the next section, Clevis configuration examples are provided, so that it is clarified what are the different options for a PKCS#11 device to be bound to an encrypted disk.
+
+##### Clevis configuration
+
+Clevis will provide a mechanism for the user to bind a particular PKCS#11 device to an encrypted device. The name of the new pin for Clevis will be `pkcs11`, and the way to configure it will be the same that is currently used:
+
+```
+$ clevis luks bind -h
+```
+
+```
+Usage: clevis luks bind [-y] [-f] [-s SLT] [-k KEY] [-t TOKEN_ID] [-e EXISTING_TOKEN_ID] -d DEV PIN CFG
+```
+
+##### Configuration to provide a PKCS#11 URI to Clevis
+As first example, a user can provide the information of the device by specifying its URI to Clevis:
+
+```
+$ clevis luks bind -d /dev/sda1 pkcs11 '{"uri": "pkcs11:model=PKCS%2315%20emulated;manufacturer=piv_II;
+serial=0a35ba26b062b9c5;token=clevis;id=%02;object=Encryption%20Key"}'
+```
+
+##### Configuration to provide a slot to Clevis
+It is possible to specify the slot where a PKCS#11 device is located through the parameters provided to the URI:
+
+```
+$ clevis luks bind -d /dev/sda1 pkcs11 '{"uri": "pkcs11:?slot-id=0"}'
+```
+
+It must be clarified that providing just the slot information will make Clevis to prompt also to select one of the available keys matched on the token in the selected slot, to avoid accidentally encryption with unwanted keys.
+
+##### Configuration to bind Clevis to the first PKCS#11 device found
+An additional option is to provide Clevis a configuration so that the first PKCS#11 device found by Clevis is bound. To do so, an empty URI can be provided as shown below:
+
+```
+$ clevis luks bind -d /dev/sda1 pkcs11 '{"uri":, "pkcs11:"}'
+```
+
+In this case, Clevis will be responsible for the detection of the device and, if no device is found, responsible for dumping the corresponding error.
+
+It must be clarified that providing an empty URI will make Clevis to prompt also to select one of the available keys matched on the token to avoid accidentally encryption with unwanted keys.
+
+##### Configuration to provide a module path to Clevis PKCS#11 pin:
+A module path can be provided to Clevis, so that it uses that module to access a device. This is only required in case the card is not supported by underlying Clevis software (OpenSC). For this reason, the module path field is completely optional. To provide the module location the user can provide the "module-path" to the "uri" Clevis configuration:
+
+```
+$ clevis-luks-bind -d /dev/sda1 pkcs11 '{"uri": "pkcs11:model=PKCS%2315%20emulated;manufacturer=piv_II;
+serial=0a35ba26b062b9c5;token=clevis;id=%02;object=Encryption%20Key?
+module-path=/usr/local/lib64/libmypkcs11.so"}'
+```
+
+As it happens with the rest of devices, encrypted disks that have been bound to a PKCS#11 device can be checked with `clevis luks list` command:
+
+```
+$ clevis luks list -d /dev/sda1
+```
+
+```
+1: pkcs11 '{"uri": "pkcs11:model=PKCS%2315%20emulated;manufacturer=piv_II;
+serial=0a35ba26b062b9c5;token=clevis;id=%02;object=Encryption%20Key?
+module-path=/usr/local/lib64/libmypkcs11.so"}'
+```
+
+For security reasons, no PIN related information will be shown.
+
+##### Configuration to provide PKCS#11 tool a different mechanism
+
+In the first phase of development, Clevis will be used in top of OpenSC to provide PKCS#11 functionality.
+OpenSC, and, in particular, `pkcs11-tool`, provides an option to indicate the mechanism to use for decryption.
+For testing purposes, some libraries, such as [SoftHSM](https://www.opendnssec.org/softhsm)), don't work with default `pkcs11-tool` mechanism,
+so it is  required to provide a particular mechanism to use. For this reason, Clevis can be provided with
+the mechanism to use, in case the default one, `RSA-PKCS-OAEP`, is not valid:
+
+```
+$ clevis luks bind -d /dev/sda1 pkcs11 '{"uri": "pkcs11:", "mechanism":"RSA-PKCS"}'
+```
+
 #### PIN: Shamir Secret Sharing
 
 Clevis provides a way to mix pins together to provide sophisticated unlocking

src/luks/clevis-luks-common-functions.in

@@ -177,6 +177,22 @@ clevis_luks_print_pin_config() {
 
     local pin=
     case "${P}" in
+    pkcs11)
+        local uri
+        uri="$(jose fmt -j- -g uri -u- <<< "${content}")"
+        mechanism="$(jose fmt -j- -g mechanism -u- <<< "${content}")"
+        if [ -z "${mechanism}" ]; then
+            pin=$(printf '{"uri":"%s"}' "${uri}")
+        else
+            pin=$(printf '{"uri":"%s", "mechanism":"%s"}' "${uri}" "${mechanism}")
+        fi
+        printf "pkcs11 '%s'" "${pin}"
+        ;;
+    sss)
+        local threshold
+        threshold=$(jose fmt -j- -Og t -o- <<< "${content}")
+        clevis_luks_process_sss_pin "${content}" "${threshold}"
+        ;;
     tang)
         local url
         url="$(jose fmt -j- -g url -u- <<< "${content}")"
@@ -197,11 +213,6 @@ clevis_luks_print_pin_config() {
         pin=${pin/#,/}
         printf "tpm2 '{%s}'" "${pin}"
         ;;
-    sss)
-        local threshold
-        threshold=$(jose fmt -j- -Og t -o- <<< "${content}")
-        clevis_luks_process_sss_pin "${content}" "${threshold}"
-        ;;
     *)
         printf "unknown pin '%s'" "${P}"
         ;;
@@ -241,6 +252,7 @@ clevis_luks_process_sss_pin() {
     local jwe="${1}"
     local threshold="${2}"
 
+    local sss_pkcs11
     local sss_tang
     local sss_tpm2
     local sss
@@ -255,6 +267,9 @@ clevis_luks_process_sss_pin() {
         fi
         read -r pin cfg <<< "${pin_cfg}"
         case "${pin}" in
+        pkcs11)
+            sss_pkcs11="${sss_pkcs11},${cfg}"
+            ;;
         tang)
             sss_tang="${sss_tang},${cfg}"
             ;;
@@ -276,6 +291,10 @@ clevis_luks_process_sss_pin() {
         cfg="${cfg},"$(clevis_luks_join_sss_cfg "tpm2" "${sss_tpm2}")
     fi
 
+    if [ -n "${sss_pkcs11}" ]; then
+        cfg="${cfg},"$(clevis_luks_join_sss_cfg "pkcs11" "${sss_pkcs11}")
+    fi
+
     if [ -n "${sss}" ]; then
         cfg=$(printf '%s,"sss":%s' "${cfg}" "${sss}")
     fi

src/luks/dracut/clevis-pin-pkcs11/clevis-pkcs11-hook.sh

@@ -0,0 +1,18 @@
+#!/bin/sh
+#
+# Copyright (c) 2024 Red Hat, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+pcscd --disable-polkit

src/luks/dracut/clevis-pin-pkcs11/meson.build

@@ -0,0 +1,18 @@
+dracut = dependency('dracut', required: false)
+
+if dracut.found()
+  dracutdir = dracut.get_pkgconfig_variable('dracutmodulesdir') + '/60' + meson.project_name() + '-pin-pkcs11'
+
+  configure_file(
+    input: 'module-setup.sh.in',
+    output: 'module-setup.sh',
+    install_dir: dracutdir,
+    configuration: data,
+  )
+
+  # TODO: install hook for pcscd start
+  install_data('clevis-pkcs11-hook.sh', install_dir: dracutdir)
+
+else
+  warning('Will not install dracut module clevis-pin-pkcs11 due to missing dependencies!')
+endif

src/luks/dracut/clevis-pin-pkcs11/module-setup.sh.in

@@ -0,0 +1,41 @@
+#!/bin/bash
+# vim: set tabstop=8 shiftwidth=4 softtabstop=4 expandtab smarttab colorcolumn=80:
+#
+# Copyright (c) 2024 Red Hat, Inc.
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+#
+# shellcheck disable=SC2154
+#
+depends() {
+    echo clevis
+    return 255
+}
+
+install() {
+    inst_hook initqueue/online 60 "${moddir}/clevis-pkcs11-hook.sh"
+    inst_hook initqueue/settled 60 "${moddir}/clevis-pkcs11-hook.sh"
+
+    inst_multiple \
+        pcscd \
+        /usr/lib64/pcsc/drivers/ifd-ccid.bundle/Contents/Linux/libccid.so \
+        /usr/lib64/pcsc/drivers/ifd-ccid.bundle/Contents/Info.plist \
+        /usr/lib64/libykcs11.so.2 \
+        /usr/lib64/opensc-pkcs11.so \
+        /usr/lib64/pkcs11/opensc-pkcs11.so \
+        pkcs11-tool \
+        clevis-decrypt-pkcs11
+
+    dracut_need_initqueue
+}

src/luks/dracut/meson.build

@@ -3,3 +3,4 @@ subdir('clevis-pin-tang')
 subdir('clevis-pin-tpm2')
 subdir('clevis-pin-sss')
 subdir('clevis-pin-null')
+subdir('clevis-pin-pkcs11')

src/luks/systemd/clevis-luks-pkcs11-askpass.in

@@ -0,0 +1,4 @@
+#!/bin/bash
+/usr/libexec/clevis-luks-pkcs11-askpin &
+# Wait 30 seconds to attend keys. If control socket receives information, this time is cancelled
+clevis-pkcs11-afunix-socket-unlock -f /run/systemd/clevis-pkcs11.sock -s 30

src/luks/systemd/clevis-luks-pkcs11-askpass.service.in

@@ -0,0 +1,8 @@
+[Unit]
+Description=Unencrypt through PKCS11
+DefaultDependencies=no
+PartOf=clevis-luks-pkcs11-askpass.socket
+
+[Service]
+Type=simple
+ExecStart=/usr/libexec/clevis-luks-pkcs11-askpass

src/luks/systemd/clevis-luks-pkcs11-askpass.socket

@@ -0,0 +1,11 @@
+# clevis pkcs11 socket
+[Unit]
+Description=Clevis PKCS11 socket handler
+Requires=clevis-luks-pkcs11-askpass.service
+After=cryptsetup-pre.target sockets.target systemd-ask-password-wall.service
+
+[Socket]
+ListenDatagram=/run/systemd/clevis-pkcs11.sock
+
+[Install]
+WantedBy=cryptsetup-pre.target sockets.target systemd-ask-password-wall.service