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From: Marco Felsch <m.felsch@pengutronix.de>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: "open list:BAREBOX" <barebox@lists.infradead.org>
Subject: Re: [PATCH 08/13] ARM: am625: support hash verification of full barebox
Date: Mon, 10 Mar 2025 20:22:26 +0100	[thread overview]
Message-ID: <20250310192226.x7g2jq6vf5rx4c7c@pengutronix.de> (raw)
In-Reply-To: <20250228-am625-secure-v1-8-4002488ff5ed@pengutronix.de>

On 25-02-28, Sascha Hauer wrote:
> This implements the necessary SoC code to check the full barebox against
> a sha256 compiled into the first stage barebox.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  arch/arm/mach-k3/Kconfig |  1 +
>  arch/arm/mach-k3/r5.c    | 14 ++++++++++++++
>  2 files changed, 15 insertions(+)
> 
> diff --git a/arch/arm/mach-k3/Kconfig b/arch/arm/mach-k3/Kconfig
> index 50919dc7e3..561ad1dac4 100644
> --- a/arch/arm/mach-k3/Kconfig
> +++ b/arch/arm/mach-k3/Kconfig
> @@ -16,6 +16,7 @@ config MACH_K3_CORTEX_R5
>  	select ELF
>  	select K3_DDRSS
>  	select FIP
> +	select HAVE_FIRMWARE_VERIFY_NEXT_IMAGE
>  	depends on 32BIT
>  	select ARM_USE_COMPRESSED_DTB
>  	default y
> diff --git a/arch/arm/mach-k3/r5.c b/arch/arm/mach-k3/r5.c
> index e12c888afa..cb52ff364d 100644
> --- a/arch/arm/mach-k3/r5.c
> +++ b/arch/arm/mach-k3/r5.c
> @@ -248,6 +248,8 @@ static int load_fip(const char *filename, off_t offset)
>  {
>  	struct fip_state *fip;
>  	struct fip_image_desc *desc;
> +	unsigned char shasum[SHA256_DIGEST_SIZE];
> +	int ret;
>  
>  	fip = fip_image_open(filename, offset);
>  	if (IS_ERR(fip)) {
> @@ -255,6 +257,18 @@ static int load_fip(const char *filename, off_t offset)
>  		return PTR_ERR(fip);
>  	}
>  
> +	if (IS_ENABLED(CONFIG_FIRMWARE_VERIFY_NEXT_IMAGE)) {
> +		ret = fip_sha256(fip, shasum);
> +		if (ret) {
> +			pr_err("Cannot calc fip sha256: %pe\n", ERR_PTR(ret));
> +			return ret;
> +		}
> +
> +		ret = firmware_next_image_verify(shasum, SHA256_DIGEST_SIZE, true);
> +		if (ret)
> +			return ret;

Albeit it would involve way more effort, I would like to see that the
FIP image format does have support for signatures within their "struct
image_desc" for each image.
This way it would be far easier for us to verify each image separately
and in a common way. Also it wouldn't require to rebuild the "r5"
tiboot3.bin to include the the updated sha256sum each time.

I do see why we can't use the externa-firmware mechanism now but I
wouldn't call it firmware_next_image_verify(). Maybe limit the scope to
fip and extent it later or remove/deprecate it once we managed to add
signatures to the FIP format.
Also the shasum size seems like the user would have a choice to choose
other sha-sums which he hasn't, therefore I would drop it.

Regards,
  Marco

> +	}
> +
>  	fip_for_each_desc(fip, desc) {
>  		struct fip_toc_entry *toc_entry = &desc->image->toc_e;
>  
> 
> -- 
> 2.39.5
> 
> 
> 



  reply	other threads:[~2025-03-10 19:23 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-28  7:16 [PATCH 00/13] am625: support secure loading " Sascha Hauer
2025-02-28  7:16 ` [PATCH 01/13] firmware: always generate sha256sum Sascha Hauer
2025-02-28  7:16 ` [PATCH 02/13] firmware: add function to verify next image Sascha Hauer
2025-03-10 18:37   ` Marco Felsch
2025-03-11  7:35     ` Sascha Hauer
2025-02-28  7:16 ` [PATCH 03/13] ARM: k3: r5: drop loading of separate binaries Sascha Hauer
2025-03-10 18:44   ` Marco Felsch
2025-02-28  7:16 ` [PATCH 04/13] ARM: k3: r5: add proper error handling Sascha Hauer
2025-03-10 18:52   ` Marco Felsch
2025-03-11  8:24     ` Sascha Hauer
2025-03-11  8:50       ` Marco Felsch
2025-02-28  7:16 ` [PATCH 05/13] fip: rework fip_image_open() Sascha Hauer
2025-02-28  7:16 ` [PATCH 06/13] fip: fix wrong function call Sascha Hauer
2025-02-28  7:16 ` [PATCH 07/13] fip: add function to calculate a sha256 over FIP image Sascha Hauer
2025-02-28  7:16 ` [PATCH 08/13] ARM: am625: support hash verification of full barebox Sascha Hauer
2025-03-10 19:22   ` Marco Felsch [this message]
2025-03-11  7:53     ` Sascha Hauer
2025-02-28  7:16 ` [PATCH 09/13] ARM: k3: add support for authenticating images against the ROM API Sascha Hauer
2025-02-28  7:16 ` [PATCH 10/13] ARM: k3: r5: delete fip image when it can't be opened Sascha Hauer
2025-02-28  7:16 ` [PATCH 11/13] ARM: k3: r5: Allow to authenticate next image by ROM API Sascha Hauer
2025-03-10 19:26   ` Marco Felsch
2025-03-11  7:54     ` Sascha Hauer
2025-02-28  7:17 ` [PATCH 12/13] scripts/k3img: remove temporary files Sascha Hauer
2025-02-28  7:17 ` [PATCH 13/13] scripts: add k3sign Sascha Hauer
2025-03-10 17:40 ` [PATCH 00/13] am625: support secure loading of full barebox Marco Felsch
2025-03-11  8:12   ` Sascha Hauer
2025-03-11  8:48     ` Marco Felsch
2025-03-11  9:13       ` Sascha Hauer

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