Hi Philippe,
On Fri, 25 Feb 2022 at 07:58, Philippe Reynes philippe.reynes@softathome.com wrote:
Add a stage pre-load that could check or modify an image.
For the moment, only a header with a signature is supported. This header has the following format:
- magic : 4 bytes
- version : 4 bytes
- header size : 4 bytes
- image size : 4 bytes
- offset image signature : 4 bytes
- flags : 4 bytes
- reserved0 : 4 bytes
- reserved1 : 4 bytes
- sha256 of the image signature : 32 bytes
- signature of the first 64 bytes : n bytes
It is a bit hard to understand without docs, but what is the point of taking the sha256 of the signature?
Also, why is the signature only of the first 64 bytes? Normally we hash the whole image and then sign that.
- image signature : n bytes
- padding : up to header size
The stage uses a node /image/pre-load/sig to get some informations:
- algo-name (mandatory) : name of the algo used to sign
- padding-name : name of padding used to sign
- signature-size : size of the signature (in the header)
- mandatory : set to yes if this sig is mandatory
- public-key (madatory) : value of the public key
Does this mean you read the DT properties to find out the sig info? I thought the point of this series was to have a signature check that did not rely on the devicetree, i.e. another layer of security?
Before running the image, the stage pre-load checks the signature provided in the header.
This is an initial support, later we could add the support of:
- ciphering
- uncompressing
- ...
Signed-off-by: Philippe Reynes philippe.reynes@softathome.com
boot/Kconfig | 55 ++++++ boot/Makefile | 1 + boot/image-pre-load.c | 416 ++++++++++++++++++++++++++++++++++++++++++ include/image.h | 14 ++ 4 files changed, 486 insertions(+) create mode 100644 boot/image-pre-load.c
Regards, Simon