build: Allow injecting GPG key at build time

flashrom doesn't work in qemu, so the firmware isn't able to update its
keyring.  Adding an already-provisioned key ahead of time works though.

Signed-off-by: Jonathon Hall <jonathon.hall@puri.sm>

Makefile

@@ -9,8 +9,10 @@ GIT_STATUS	:= $(shell \
 	fi)
 HEADS_GIT_VERSION	:= $(shell git describe --tags --dirty)
 
-CB_OUTPUT_FILE		:= heads-$(BOARD)-$(HEADS_GIT_VERSION).rom
-CB_BOOTBLOCK_FILE	:= heads-$(BOARD)-$(HEADS_GIT_VERSION).bootblock
+CB_OUTPUT_BASENAME	:= heads-$(BOARD)-$(HEADS_GIT_VERSION)
+CB_OUTPUT_FILE		:= $(CB_OUTPUT_BASENAME).rom
+CB_OUTPUT_FILE_GPG_INJ	:= $(CB_OUTPUT_BASENAME)-gpg-injected.rom
+CB_BOOTBLOCK_FILE	:= $(CB_OUTPUT_BASENAME).bootblock
 LB_OUTPUT_FILE		:= linuxboot-$(BOARD)-$(HEADS_GIT_VERSION).rom
 
 all:
@@ -580,6 +582,18 @@ modules.clean:
 		rm "build/$$dir/.configured" ; \
 	done
 
+# Inject a GPG key into the image - this is most useful when testing in qemu,
+# since we can't reflash the firmware in qemu to update the keychain.  Instead,
+# inject the public key ahead of time.  Specify the location of the key with
+# PUBKEY_ASC.
+inject_gpg: $(build)/$(BOARD)/$(CB_OUTPUT_FILE_GPG_INJ)
+
+$(build)/$(BOARD)/$(CB_OUTPUT_BASENAME)-gpg-injected.rom: $(build)/$(BOARD)/$(CB_OUTPUT_FILE)
+	cp "$(build)/$(BOARD)/$(CB_OUTPUT_FILE)" \
+		"$(build)/$(BOARD)/$(CB_OUTPUT_FILE_GPG_INJ)"
+	./bin/inject_gpg_key.sh --cbfstool "$(build)/$(coreboot_dir)/cbfstool" \
+		"$(build)/$(BOARD)/$(CB_OUTPUT_FILE_GPG_INJ)" "$(PUBKEY_ASC)"
+
 real.clean:
 	for dir in \
 		$(module_dirs) \

bin/inject_gpg_key.sh

@@ -0,0 +1,123 @@
+#! /usr/bin/env bash
+
+set -e
+
+function usage() {
+	cat <<USAGE_END
+usage:
+	$0 [options...] <pureboot.rom> <pubkey.asc>
+	$0 --help
+
+parameters:
+	-v|--verbose: Show verbose messages
+	--cbfstool <path>: Specify location of cbfstool (otherwise look in PATH)
+	--keep: Keep temporary GPG directory (use --verbose to see location)
+	<pureboot.rom>: Path to a ROM whose GPG keyring will be replaced.
+	<pubkey.asc>: GPG public key to store in the ROM.  The entire keychain is
+		replaced.
+	--help: Show this help
+USAGE_END
+}
+
+VERBOSE=
+KEEP=
+PUREBOOT_ROM=
+PUBKEY_ASC=
+CBFSTOOL=
+
+function log() {
+	echo "$@" >&2
+}
+
+function verb() {
+	if [ -n "$VERBOSE" ]; then
+		log "$@"
+	fi
+}
+
+function die() {
+	log "$@"
+	exit 1
+}
+
+while [ $# -gt 0 ]; do
+	case "$1" in
+		--help)
+			usage
+			exit 0
+			;;
+		--cbfstool)
+			CBFSTOOL="$2"
+			shift
+			shift
+			;;
+		-v|--verbose)
+			VERBOSE=y
+			shift
+			;;
+		--keep)
+			KEEP=y
+			shift
+			;;
+		--)
+			shift
+			break
+			;;
+		*)
+			break
+			;;
+	esac
+done
+
+if [ -z "$CBFSTOOL" ]; then
+	if ! command -v cbfstool &>/dev/null; then
+		die "cbfstool is not present in PATH, install or specify with --cbfstool"
+	fi
+	CBFSTOOL=cbfstool
+else
+	if [ ! -x "$CBFSTOOL" ]; then
+		die "$CBFSTOOL is not executable, check argument to --cbfstool"
+	fi
+fi
+
+PUREBOOT_ROM="$1"
+PUBKEY_ASC="$2"
+
+log "Inserting $PUBKEY_ASC into $PUREBOOT_ROM..."
+
+GPG_HOME="$(mktemp --tmpdir --directory "tmp-$(basename "$0")-XXX")"
+verb "Creating GPG keyring in $GPG_HOME"
+if [ -z "$KEEP" ]; then
+	trap 'rm -rf -- "$GPG_HOME"' EXIT
+fi
+
+function gpg_with_args() {
+	# Set the GPG home directory with --homedir.  This will use a keyring in
+	# that directory and also will avoid loading any user config that could
+	# interfere.
+	gpg --homedir "$GPG_HOME" "$@"
+}
+
+verb "Importing $PUBKEY_ASC"
+gpg_with_args --import <"$PUBKEY_ASC"
+# Trust this key, it is the only one in this keyring
+verb "Trusting user-specified keys"
+gpg_with_args --list-keys --fingerprint --with-colons | sed -E -n -e 's/^fpr:::::::::([0-9A-F]+):$/\1:6:/p' | gpg_with_args --import-ownertrust
+gpg_with_args --update-trust
+
+verb "Cleaning existing keyring from $PUREBOOT_ROM"
+for gpgfile in pubring.kbx pubring.gpg trustdb.gpg; do
+	if "$CBFSTOOL" "$PUREBOOT_ROM" print | grep -q "^heads/initrd/.gnupg/$gpgfile "; then
+		verb "Found heads/initrd/.gnupg/$gpgfile, removing"
+		"$CBFSTOOL" "$PUREBOOT_ROM" remove -n "heads/initrd/.gnupg/$gpgfile"
+	fi
+done
+
+verb "Adding new keyring to $PUREBOOT_ROM"
+for gpgfile in pubring.kbx trustdb.gpg; do
+	"$CBFSTOOL" "$PUREBOOT_ROM" add -f "$GPG_HOME/$gpgfile" -n "heads/initrd/.gnupg/$gpgfile" -t raw
+done
+
+# Nothing is currently done with otrust.txt or config.user, if they were
+# present they are kept.
+log "Success"