Add documentation highlighting the steps for using the uefi capsule update feature for updating the u-boot firmware image.
Signed-off-by: Sughosh Ganu sughosh.ganu@linaro.org ---
Changes since V3: None
doc/board/emulation/index.rst | 1 + doc/board/emulation/qemu_capsule_update.rst | 210 ++++++++++++++++++++ 2 files changed, 211 insertions(+) create mode 100644 doc/board/emulation/qemu_capsule_update.rst
diff --git a/doc/board/emulation/index.rst b/doc/board/emulation/index.rst index 1adefee155..a09ead1c35 100644 --- a/doc/board/emulation/index.rst +++ b/doc/board/emulation/index.rst @@ -10,3 +10,4 @@ Emulation qemu-mips qemu-riscv qemu-x86 + qemu_capsule_update diff --git a/doc/board/emulation/qemu_capsule_update.rst b/doc/board/emulation/qemu_capsule_update.rst new file mode 100644 index 0000000000..9fec75f8f1 --- /dev/null +++ b/doc/board/emulation/qemu_capsule_update.rst @@ -0,0 +1,210 @@ +.. SPDX-License-Identifier: GPL-2.0+ +.. Copyright (C) 2020, Linaro Limited + +Enabling UEFI Capsule Update feature +------------------------------------ + +Support has been added for the UEFI capsule update feature which +enables updating the U-Boot image using the UEFI firmware management +protocol (fmp). The capsules are not passed to the firmware through +the UpdateCapsule runtime service. Instead, capsule-on-disk +functionality is used for fetching the capsule from the EFI System +Partition (ESP) by placing the capsule file under the +\EFI\UpdateCapsule directory. + +Currently, support has been added on the QEMU ARM64 virt platform for +updating the U-Boot binary as a raw image when the platform is booted +in non-secure mode, i.e. with CONFIG_TFABOOT disabled. For this +configuration, the QEMU platform needs to be booted with +'secure=off'. The U-Boot binary placed on the first bank of the NOR +flash at offset 0x0. The U-Boot environment is placed on the second +NOR flash bank at offset 0x4000000. + +The capsule update feature is enabled with the following configuration +settings:: + + CONFIG_MTD=y + CONFIG_FLASH_CFI_MTD=y + CONFIG_CMD_MTDPARTS=y + CONFIG_CMD_DFU=y + CONFIG_DFU_MTD=y + CONFIG_PCI_INIT_R=y + CONFIG_EFI_CAPSULE_ON_DISK=y + CONFIG_EFI_CAPSULE_FIRMWARE_MANAGEMENT=y + CONFIG_EFI_CAPSULE_FIRMWARE=y + CONFIG_EFI_CAPSULE_FIRMWARE_RAW=y + CONFIG_EFI_CAPSULE_FMP_HEADER=y + +In addition, the following config needs to be disabled(QEMU ARM specific):: + + CONFIG_TFABOOT + +The capsule file can be generated by using the GenerateCapsule.py +script in EDKII:: + + $ ./BaseTools/BinWrappers/PosixLike/GenerateCapsule -e -o \ + <capsule_file_name> --fw-version <val> --lsv <val> --guid \ + e2bb9c06-70e9-4b14-97a3-5a7913176e3f --verbose --update-image-index \ + <val> --verbose <u-boot.bin> + +The above is a wrapper script(GenerateCapsule) which eventually calls +the actual GenerateCapsule.py script. + +As per the UEFI specification, the capsule file needs to be placed on +the EFI System Partition, under the \EFI\UpdateCapsule directory. The +EFI System Partition can be a virtio-blk-device. + +Before initiating the firmware update, the efi variables BootNext, +BootXXXX and OsIndications need to be set. The BootXXXX variable needs +to be pointing to the EFI System Partition which contains the capsule +file. The BootNext, BootXXXX and OsIndications variables can be set +using the following commands:: + + => efidebug boot add 0 Boot0000 virtio 0:1 <capsule_file_name> + => efidebug boot next 0 + => setenv -e -nv -bs -rt -v OsIndications =0x04 + => saveenv + +Finally, the capsule update can be initiated with the following +command:: + + => efidebug capsule disk-update + +The updated U-Boot image will be booted on subsequent boot. + +Enabling Capsule Authentication +^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The UEFI specification defines a way of authenticating the capsule to +be updated by verifying the capsule signature. The capsule signature +is computed and prepended to the capsule payload at the time of +capsule generation. This signature is then verified by using the +public key stored as part of the X509 certificate. This certificate is +in the form of an efi signature list (esl) file, which is embedded as +part of the platform's device tree blob using the mkeficapsule +utility. + +On the QEMU virt platforms, the device-tree is generated on the fly +based on the devices configured. This device tree is then passed on to +the various software components booting on the platform, including +U-Boot. Therefore, on the QEMU virt platform, the signatute is +embedded on an overlay. This overlay is then applied at runtime to the +base platform device-tree. Steps needed for embedding the esl file in +the overlay are highlighted below. + +The capsule authentication feature can be enabled through the +following config, in addition to the configs listed above for capsule +update:: + + CONFIG_EFI_CAPSULE_AUTHENTICATE=y + +The public and private keys used for the signing process are generated +and used by the steps highlighted below:: + + 1. Install utility commands on your host + * OPENSSL + * efitools + + 2. Create signing keys and certificate files on your host + + $ openssl req -x509 -sha256 -newkey rsa:2048 -subj /CN=CRT/ \ + -keyout CRT.key -out CRT.crt -nodes -days 365 + $ cert-to-efi-sig-list CRT.crt CRT.esl + + $ openssl x509 -in CRT.crt -out CRT.cer -outform DER + $ openssl x509 -inform DER -in CRT.cer -outform PEM -out CRT.pub.pem + + $ openssl pkcs12 -export -out CRT.pfx -inkey CRT.key -in CRT.crt + $ openssl pkcs12 -in CRT.pfx -nodes -out CRT.pem + +The capsule file can be generated by using the GenerateCapsule.py +script in EDKII:: + + $ ./BaseTools/BinWrappers/PosixLike/GenerateCapsule -e -o \ + <capsule_file_name> --monotonic-count <val> --fw-version \ + <val> --lsv <val> --guid \ + e2bb9c06-70e9-4b14-97a3-5a7913176e3f --verbose \ + --update-image-index <val> --signer-private-cert \ + /path/to/CRT.pem --trusted-public-cert \ + /path/to/CRT.pub.pem --other-public-cert /path/to/CRT.pub.pem \ + <u-boot.bin> + +Place the capsule generated in the above step on the EFI System +Partition under the EFI/UpdateCapsule directory + +For embedding the public key certificate, the following steps need to +be followed:: + + 1. Generate a skeleton overlay dts file, with a single fragment + node and an empty __overlay__ node + + A typical skeleton overlay file will look like this + + /dts-v1/; + /plugin/; + + / { + fragment@0 { + target-path = "/"; + __overlay__ { + }; + }; + }; + + + 2. Convert the dts to a corresponding dtb with the following + command + ./scripts/dtc/dtc -@ -I dts -O dtb -o <ov_dtb_file_name> \ + <dts_file> + + 3. Run the dtb file generated above through the mkeficapsule tool + in U-Boot + ./tools/mkeficapsule -O <pub_key.esl> -D <ov_dtb> + +Running the above command results in the creation of a 'signature' +node in the dtb, under which the public key is stored as a +'capsule-key' property. The '-O' option is to be used since the +public key certificate(esl) file is being embedded in an overlay. + +The dtb file embedded with the certificate is now to be placed on an +EFI System Partition. This would then be loaded and "merged" with the +base platform flattened device-tree(dtb) at runtime. + +Build U-Boot with the following steps(QEMU ARM64):: + + $ make qemu_arm64_defconfig + $ make menuconfig + Disable CONFIG_TFABOOT + Enable CONFIG_EFI_CAPSULE_AUTHENTICATE + Enable all configs needed for capsule update(listed above) + $ make all + +Boot the platform and perform the following steps on the U-Boot +command line:: + + 1. Enable capsule authentication by setting the following env + variable + + => setenv capsule_authentication_enabled 1 + => saveenv + + 2. Load the overlay dtb to memory and merge it with the base fdt + + => fatload virtio 0:1 <$fdtovaddr> EFI/<ov_dtb_file> + => fdt addr $fdtcontroladdr + => fdt resize <size_of_ov_dtb_file> + => fdt apply <$fdtovaddr> + + 3. Set the following environment and UEFI boot variables + + => setenv -e -nv -bs -rt -v OsIndications =0x04 + => efidebug boot add 0 Boot0000 virtio 0:1 <capsule_file_name> + => efidebug boot next 0 + => saveenv + + 4. Finally, the capsule update can be initiated with the following + command + + => efidebug capsule disk-update + +On subsequent reboot, the platform should boot the updated U-Boot binary.