crypt-gpg: For GnuPG >= 2.1 support OpenPGP smartcards

modules.d/91crypt-gpg/crypt-gpg-lib.sh

@@ -4,7 +4,7 @@ command -v ask_for_password >/dev/null || . /lib/dracut-crypt-lib.sh
 
 # gpg_decrypt mnt_point keypath keydev device
 #
-# Decrypts encrypted symmetrically key to standard output.
+# Decrypts symmetrically encrypted (password or OpenPGP smartcard) key to standard output.
 #
 # mnt_point - mount point where <keydev> is already mounted
 # keypath - GPG encrypted key path relative to <mnt_point>
@@ -22,10 +22,40 @@ gpg_decrypt() {
 
     mkdir -m 0700 -p "$gpghome"
 
+    # Setup GnuPG home and gpg-agent for usage of OpenPGP smartcard.
+    # This requires GnuPG >= 2.1, as it uses the new ,,pinentry-mode´´
+    # feature, which - when set to ,,loopback´´ - allows us to pipe
+    # the smartcard's pin to GnuPG (instead of using a normal pinentry
+    # program needed with GnuPG < 2.1), making for uncomplicated
+    # integration with the existing codebase.
+    local useSmartcard="0"
+    local gpgMajorVersion="$(gpg --version | sed -n 1p | sed -n -r -e 's|.* ([0-9]*).*|\1|p')"
+    local gpgMinorVersion="$(gpg --version | sed -n 1p | sed -n -r -e 's|.* [0-9]*\.([0-9]*).*|\1|p')"
+
+    if [ "${gpgMajorVersion}" -ge 2 ] && [ "${gpgMinorVersion}" -ge 1 ] \
+            && [ -f /root/crypt-public-key.gpg ] && getargbool 1 rd.luks.smartcard ; then
+        useSmartcard="1"
+        echo "allow-loopback-pinentry" >> "$gpghome/gpg-agent.conf"
+        GNUPGHOME="$gpghome" gpg-agent --quiet --daemon
+        GNUPGHOME="$gpghome" gpg --quiet --no-tty --import < /root/crypt-public-key.gpg
+        local smartcardSerialNumber="$(GNUPGHOME=$gpghome gpg --no-tty --card-status \
+            | sed -n -r -e 's|Serial number.*: ([0-9]*)|\1|p' | tr -d '\n')"
+        if [ -n "${smartcardSerialNumber}" ]; then
+            inputPrompt="PIN (OpenPGP card ${smartcardSerialNumber})"
+        fi
+        GNUPGHOME="$gpghome" gpg-connect-agent 1>/dev/null learn /bye
+        opts="$opts --pinentry-mode=loopback"
+    fi
+
     ask_for_password \
         --cmd "gpg $opts --decrypt $mntp/$keypath" \
-        --prompt "Password ($keypath on $keydev for $device)" \
+        --prompt "${inputPrompt:-Password ($keypath on $keydev for $device)}" \
         --tries 3 --tty-echo-off
 
+    # Clean up the smartcard gpg-agent
+    if [ "${useSmartcard}" == "1" ]; then
+        GNUPGHOME="$gpghome" gpg-connect-agent 1>/dev/null killagent /bye
+    fi
+
     rm -rf -- "$gpghome"
 }

modules.d/91crypt-gpg/module-setup.sh

@@ -5,6 +5,12 @@
 check() {
     require_binaries gpg || return 1
 
+    if [ -f "${initdir}/root/crypt-public-key.gpg" ]; then
+        require_binaries gpg-agent || return 1
+        require_binaries gpg-connect-agent || return 1
+        require_binaries /usr/libexec/scdaemon || return 1
+    fi
+
     return 255
 }
 
@@ -17,4 +23,15 @@ depends() {
 install() {
     inst_multiple gpg
     inst "$moddir/crypt-gpg-lib.sh" "/lib/dracut-crypt-gpg-lib.sh"
+
+    local gpgMajorVersion="$(gpg --version | sed -n 1p | sed -n -r -e 's|.* ([0-9]*).*|\1|p')"
+    local gpgMinorVersion="$(gpg --version | sed -n 1p | sed -n -r -e 's|.* [0-9]*\.([0-9]*).*|\1|p')"
+    if [ "${gpgMajorVersion}" -ge 2 ] && [ "${gpgMinorVersion}" -ge 1 ] && [ -f /etc/dracut.conf.d/crypt-public-key.gpg ]; then
+        inst_multiple gpg-agent
+        inst_multiple gpg-connect-agent
+        inst_multiple /usr/libexec/scdaemon || derror "crypt-gpg: gnugpg with scdaemon required for smartcard support in the initramfs"
+        cp "/etc/dracut.conf.d/crypt-public-key.gpg" "${initdir}/root/"
+    elif [ -f /etc/dracut.conf.d/crypt-public-key.gpg ]; then
+        dwarning "crypt-gpg: gnupg >= 2.1 required for smartcard support in the initramfs"
+    fi
 }