[PATCH v10 10/15] FWU: Add support for the FWU Multi Bank Update feature

[Jassi Brar]

Hi Etienne,

On Wed, Sep 28, 2022 at 2:30 AM Etienne Carriere
<etienne.carriere at linaro.org> wrote:
> Hello Jassi, Sughosh and all,
>
>  >>> But a malicious user may force some old vulnerable image back into use
>  >>> by updating all but that image.
>
> When the system boots with accepted images (referring to fwu-mdata
> regular/trial state), the platform monotonic counter is updated
> against booted image version number if needed, preventing older images
> to be booted when an accepted image has been deployed.
> @Jassi, does this answer your question?
>
As I said in my earlier post, I know we can employ security+integrity
techniques to prevent such misuse.
My point is FWU should still be implemented assuming no such technique
might be available due to any reason, and we do the best we can. Just
as we don't say lets not care about buffer-overflow vulnerabilities
because the system can implement secure boot and other such
techniques.

For example, the spec warns : "The metadata can be maliciously
crafted, it should be treated as an insecure information source." So
clearly the spec doesn't count on rollback and authentication
mechanisms to be always available - and that is how it should be.

cheers.