From: Jan Kiszka jan.kiszka@siemens.com
There are many ways to get a signed firmware for the IOT2050 devices, namely for the parts under user-control. This script documents one way of doing it, given a signing key. Augment the board documentation with the required procedure around it.
Signed-off-by: Jan Kiszka jan.kiszka@siemens.com --- doc/board/siemens/iot2050.rst | 52 +++++++++++++++++++++++++++++++++++ tools/iot2050-sign-fw.sh | 51 ++++++++++++++++++++++++++++++++++ 2 files changed, 103 insertions(+) create mode 100755 tools/iot2050-sign-fw.sh
diff --git a/doc/board/siemens/iot2050.rst b/doc/board/siemens/iot2050.rst index 26972e20ae9..4e0925c72c9 100644 --- a/doc/board/siemens/iot2050.rst +++ b/doc/board/siemens/iot2050.rst @@ -79,3 +79,55 @@ Via external programmer Dediprog SF100 or SF600: .. code-block:: text
$ dpcmd --vcc 2 -v -u flash.bin + +Signing (optional) +------------------ + +To enable verified boot for the firmware artifacts after the Siemens-managed +first-stage loader (seboot_pg*.bin), the following steps need to be taken +before and after the build: + +Generate dtsi holding the public key +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +.. code-block:: text + + tools/key2dtsi.py -c -s key.pem public-key.dtsi + +This will be used to embed the public key into U-Boot SPL and main so that each +step can validate signatures of the succeeding one. + +Adjust U-Boot configuration +^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +Enabled at least the following options in U-Boot: + +.. code-block:: text + + CONFIG_SPL_FIT_SIGNATURE=y + CONFIG_DEVICE_TREE_INCLUDES="/path/to/public-key.dtsi" + CONFIG_RSA=y + +Note that there are more configuration changes needed in order to lock-down +the command line and the boot process of U-Boot for secure scenarios. These are +not in scope here. + +Build U-Boot +^^^^^^^^^^^^ + +See related section above. + +Sign flash.bin +^^^^^^^^^^^^^^ + +In the build folder still containing artifacts from step 3, invoke: + +.. code-block:: text + + tools/iot2050-sign-fw.sh /path/to/key.pem + +Flash signed flash.bin +^^^^^^^^^^^^^^^^^^^^^^ + +The signing has happen in-place in flash.bin, thus the flashing procedure +described above. diff --git a/tools/iot2050-sign-fw.sh b/tools/iot2050-sign-fw.sh new file mode 100755 index 00000000000..4d1d79498c2 --- /dev/null +++ b/tools/iot2050-sign-fw.sh @@ -0,0 +1,51 @@ +#!/bin/sh + +if [ -z "$1" ]; then + echo "Usage: $0 KEY" + exit 1 +fi + +TEMP_X509=$(mktemp XXXXXXXX.temp) + +REVISION=${2:-0} +SHA_VAL=$(openssl dgst -sha512 -hex tispl.bin | sed -e "s/^.*= //g") +BIN_SIZE=$(stat -c %s tispl.bin) + +cat <<EOF >$TEMP_X509 +[ req ] +distinguished_name = req_distinguished_name +x509_extensions = v3_ca +prompt = no +dirstring_type = nobmp + +[ req_distinguished_name ] +CN = IOT2050 Firmware Signature + +[ v3_ca ] +basicConstraints = CA:true +1.3.6.1.4.1.294.1.3 = ASN1:SEQUENCE:swrv +1.3.6.1.4.1.294.1.34 = ASN1:SEQUENCE:sysfw_image_integrity + +[ swrv ] +swrv = INTEGER:$REVISION + +[ sysfw_image_integrity ] +shaType = OID:2.16.840.1.101.3.4.2.3 +shaValue = FORMAT:HEX,OCT:$SHA_VAL +imageSize = INTEGER:$BIN_SIZE +EOF + +CERT_X509=$(mktemp XXXXXXXX.crt) + +openssl req -new -x509 -key $1 -nodes -outform DER -out $CERT_X509 -config $TEMP_X509 -sha512 +cat $CERT_X509 tispl.bin > tispl.bin_signed +# currently broken in upstream +#source/tools/binman/binman replace -i flash.bin -f tispl.bin_signed blob@0x180000 +dd if=tispl.bin_signed of=flash.bin bs=$((0x1000)) seek=$((0x180000/0x1000)) conv=notrunc + +rm $TEMP_X509 $CERT_X509 + +tools/mkimage -G $1 -r -o sha256,rsa4096 -F fit@0x380000.fit +# currently broken in upstream +#source/tools/binman/binman replace -i flash.bin -f fit@0x380000.fit fit@0x380000 +dd if=fit@0x380000.fit of=flash.bin bs=$((0x1000)) seek=$((0x380000/0x1000)) conv=notrunc