[U-Boot] [RFC][PATCH] spl: vboot: Verify content before using load_addr

[Teddy Reed]

On Wed, Jun 6, 2018 at 4:35 AM, Jun Nie <jun.nie at linaro.org> wrote:
> 2018-06-06 9:08 GMT+08:00 Teddy Reed <teddy.reed at gmail.com>:
>> When using verified-boot in the SPL, the FIT content must be
>> verified before it can be used.
>>
>> Currently the load_addr FIT property is read and used as input to
>> memcpy before the property is verified.
>>
>> Signed-off-by: Teddy Reed <teddy.reed at gmail.com>
>> ---
>
> Reviewed-by: Jun Nie <jun.nie at linaro.org>

Thanks for taking a look Jun! I did not see any sandbox tests
exercising the SPL/signature checking so I included 'RFC'. I know you
are familiar with using the signature checking within the SPL, and you
helped make it possible in the first place.

The three minor concerns I had when moving the validation earlier are:
(1) the signature was originally calculated on the potentially
uncompressed version, but this seems unlikely; similarly (2) the post
process board-specific methods can mutate the signed content; and (3)
now using the src address means reading directly from storage / etc
instead of potentially SRAM/DRAM.

For (1) see that line 256 was uncompressing the data before signature
checking. Then the signature check was applied to the uncompressed
region. To be clear I think this patch is the correct approach, and
the signature check should apply to the compressed content.

For (2) see that line 248 is board-specific, I am assuming that can
mutate the content. Thus the signature check should be placed before
that call.

Thanks again!

-- 
Teddy Reed V