On Mon, Nov 13, 2017 at 2:45 PM, Maxime Ripard
<maxime.rip...@free-electrons.com> wrote:
> Hi,
>
> On Fri, Nov 10, 2017 at 10:21:10PM +0530, Jagan Teki wrote:
>> Add verified-boot documentation for sunxi a64 platform.
>>
>> Signed-off-by: Jagan Teki <ja...@amarulasolutions.com>
>> ---
>> Changes for v2:
>> - New patch
>>
>> board/sunxi/README.sunxi64 | 177
>> +++++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 177 insertions(+)
>>
>> diff --git a/board/sunxi/README.sunxi64 b/board/sunxi/README.sunxi64
>> index c492f74..5a2fe69 100644
>> --- a/board/sunxi/README.sunxi64
>> +++ b/board/sunxi/README.sunxi64
>> @@ -160,6 +160,183 @@ Then write this image to a microSD card, replacing
>> /dev/sdx with the right
>> device file (see above):
>> $ dd if=firmware.img of=/dev/sdx bs=8k seek=1
>>
>> +Verified Boot
>> +=============
>> +
>> +U-Boot supports an image verification method called "Verified Boot".
>> +This is a brief tutorial to utilize this feature for the Sunxi A64 platform.
>> +You will find details documents in the doc/uImage.FIT directory.
>> +
>> +Here, we take Orangepi Win board for example, but it should work for any
>> +other boards including 32 bit SoCs.
>
> It should be in another file then I guess?
>
>> +1. Generate RSA key to sign
>> +
>> + $ mkdir keys
>> + $ openssl genpkey -algorithm RSA -out keys/dev.key \
>> + -pkeyopt rsa_keygen_bits:2048 -pkeyopt rsa_keygen_pubexp:65537
>> + $ openssl req -batch -new -x509 -key keys/dev.key -out keys/dev.crt
>> +
>> +Two files "dev.key" and "dev.crt" will be created. The base name is
>> arbitrary,
>> +but need to match to the "key-name-hint" property described below.
>> +
>> +2. FIT Input
>> +
>> +---------------------------------------->8----------------------------------------
>> +/dts-v1/;
>> +/ {
>> + description = "FIT image with single Linux kernel, FDT blob";
>> + #address-cells = <1>;
>> +
>> + images {
>> + kernel@0 {
>> + description = "ARM64 Linux kernel";
>> + data =
>> /incbin/("/path/to/linux/dir/arch/arm64/boot/Image.gz");
>> + type = "kernel";
>> + arch = "arm64";
>> + os = "linux";
>> + compression = "gzip";
>> + load = <0x50080000>;
>> + entry = <0x50080000>;
>> + hash@1 {
>> + algo = "sha256";
>> + };
>> + };
>> +
>> + fdt@0 {
>> + description = "Orangepi Win/Win+ Devicetree blob";
>> + data =
>> /incbin/("/path/to/linux/dir/arch/arm64/boot/dts/allwinner/sun50i-a64-orangepi-win.dtb");
>> + type = "flat_dt";
>> + arch = "arm64";
>> + compression = "none";
>> + hash@1 {
>> + algo = "sha256";
>> + };
>> + };
>> + };
>> +
>> + configurations {
>> + default = "conf@0";
>> +
>> + conf@0 {
>> + description = "Boot Linux kernel, FDT blob";
>> + kernel = "kernel@0";
>> + fdt = "fdt@0";
>> + signature@0 {
>> + algo = "sha256,rsa2048";
>> + key-name-hint = "dev";
>> + sign-images = "kernel", "fdt";
>> + };
>> + };
>> + };
>> +};
>> +---------------------------------------->8----------------------------------------
>> +
>> +You need to change the two '/incbin/' lines, depending on the location of
>> +your kernel image and devicetree blob. The "load" and "entry" properties
>> also
>> +need to be adjusted if you want to change the physical placement of the
>> kernel.
>> +
>> +The "key-name-hint" must specify the key name you have created in the step
>> 1.
>> +
>> +The FIT file name is arbitrary. Let's say you saved it into "fit.its".
>> +
>> +3. Compile U-Boot with FIT and signature enabled
>> +
>> +To use the Verified Boot, you need to enable the following two options:
>> + CONFIG_FIT
>> + CONFIG_FIT_SIGNATURE
>> +
>> + $ make orangepi_win_defconfig
>> + $ make CROSS_COMPILE=aarch64-linux-gnu-
>> +
>> +4. FIT Output
>> +
>> +After building U-Boot, you will see tools/mkimage. With this tool, you can
>> +create an image tree blob as follows:
>> +
>> + $ tools/mkimage -f fit.its -k keys -K dts/dt.dtb -r -F fitImage
>> +
>> +The -k option must specify the key directory you have created in step 1.
>> +
>> +A file "fitImage" will be created. This includes kernel, DTB,
>> +hash data for each of the three, and signature data.
>> +
>> +The public key needed for the run-time verification is stored in
>> "dts/dt.dtb".
>> +
>> +5. Compile Verified U-Boot
>> +
>> +Since the "dt.dtb" has been updated in step 4, you need to re-compile the
>> +U-Boot.
>> +
>> + $ make CROSS_COMPILE=aarch64-linux-gnu-
>> +
>> +The re-compiled "u-boot.bin" is appended with DTB that contains the public
>> key.
>> +
>> +6. Flash the image
>> +
>> +Flash the "fitImage" to a storage device (SD, NAND, eMMC, or whatever) on
>> your
>> +board.
>> +
>> +7. Boot verified kernel
>> +
>> +Load the fitImage to memory and run the following from the U-Boot command
>> line.
>> +
>> + > bootm <addr>
>> +
>> +Here, <addr> is the base address of the fitImage.
>> +
>> +If it is successful, you will see messages like follows:
>> +
>> +---------------------------------------->8----------------------------------------
>> +=> setenv bootargs console=ttyS0,115200 earlyprintk root=/dev/mmcblk0p1
>> rootwait
>> +=> ext4load mmc 0:1 $kernel_addr_r /boot/fitImage
>> +16321738 bytes read in 1049 ms (14.8 MiB/s)
>> +=> bootm $kernel_addr_r
>> +## Loading kernel from FIT Image at 40080000 ...
>> + Using 'conf@0' configuration
>> + Verifying Hash Integrity ... OK
>> + Trying 'kernel@0' kernel subimage
>> + Description: ARM64 Linux kernel
>> + Type: Kernel Image
>> + Compression: gzip compressed
>> + Data Start: 0x400800e4
>> + Data Size: 6884659 Bytes = 6.6 MiB
>> + Architecture: AArch64
>> + OS: Linux
>> + Load Address: 0x50080000
>> + Entry Point: 0x50080000
>> + Hash algo: sha256
>> + Hash value:
>> 6808fe51ea3c15f31c4510d2701d4707b56d20213c9da05bce79fb53bf108f1a
>> + Verifying Hash Integrity ... sha256+ OK
>> +## Loading fdt from FIT Image at 40080000 ...
>> + Using 'conf@0' configuration
>> + Trying 'fdt@0' fdt subimage
>> + Description: Orangepi Win/Win+ Devicetree blob
>> + Type: Flat Device Tree
>> + Compression: uncompressed
>> + Data Start: 0x40710f24
>> + Data Size: 9032 Bytes = 8.8 KiB
>> + Architecture: AArch64
>> + Hash algo: sha256
>> + Hash value:
>> ca3d874cd10466633ff133cc0156828d48c8efb96987fa45f885761d22a25dc1
>> + Verifying Hash Integrity ... sha256+ OK
>> + Booting using the fdt blob at 0x40710f24
>> + Uncompressing Kernel Image ... OK
>> + Loading Device Tree to 0000000049ffa000, end 0000000049fff347 ... OK
>> +
>> +Starting kernel ...
>> +---------------------------------------->8----------------------------------------
>> +
>> +Please pay attention to the lines that start with "Verifying Hash
>> Integrity".
>> +
>> +"Verifying Hash Integrity ... sha256,rsa2048:dev+ OK" means the signature
>> check
>> +passed.
>> +
>> +"Verifying Hash Integrity ... sha256+ OK" (2 times) means the hash check
>> passed
>> +for kernel and DTB.
>> +
>> +If they are not displayed, the Verified Boot is not working.
>
> One thing that we should make *really* clear is that it will sign only
> the kernel and device trees, but it's far from sufficient to implement
> a full fledged secure boot, and you shouldn't consider your device
> protected. At least the signature of the SPL and the U-Boot binary are
> missing to implement something that would have a chance to qualify.
True, full secure boot can be an extension of this. will update these
in next series.
thanks!
--
Jagan Teki
Free Software Engineer | www.openedev.com
U-Boot, Linux | Upstream Maintainer
Hyderabad, India.
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