linux-kernel - Re: [PATCH v3] powerpc/pseries: detect secure and trusted boot state of the system.

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Message-ID: <20200716081337.GB32107@kitsune.suse.cz>
Date:   Thu, 16 Jul 2020 10:13:38 +0200
From:   Michal Suchánek <msuchanek@...e.de>
To:     Nayna Jain <nayna@...ux.ibm.com>
Cc:     linuxppc-dev@...abs.org, linux-kernel@...r.kernel.org,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Daniel Axtens <dja@...ens.net>
Subject: Re: [PATCH v3] powerpc/pseries: detect secure and trusted boot state
 of the system.

On Wed, Jul 15, 2020 at 07:52:01AM -0400, Nayna Jain wrote:
> The device-tree property to check secure and trusted boot state is
> different for guests(pseries) compared to baremetal(powernv).
> 
> This patch updates the existing is_ppc_secureboot_enabled() and
> is_ppc_trustedboot_enabled() functions to add support for pseries.
> 
> The secureboot and trustedboot state are exposed via device-tree property:
> /proc/device-tree/ibm,secure-boot and /proc/device-tree/ibm,trusted-boot
> 
> The values of ibm,secure-boot under pseries are interpreted as:
                                      ^^^
> 
> 0 - Disabled
> 1 - Enabled in Log-only mode. This patch interprets this value as
> disabled, since audit mode is currently not supported for Linux.
> 2 - Enabled and enforced.
> 3-9 - Enabled and enforcing; requirements are at the discretion of the
> operating system.
> 
> The values of ibm,trusted-boot under pseries are interpreted as:
                                       ^^^
These two should be different I suppose?

Thanks

Michal
> 0 - Disabled
> 1 - Enabled
> 
> Signed-off-by: Nayna Jain <nayna@...ux.ibm.com>
> Reviewed-by: Daniel Axtens <dja@...ens.net>
> ---
> v3:
> * fixed double check. Thanks Daniel for noticing it.
> * updated patch description.
> 
> v2:
> * included Michael Ellerman's feedback.
> * added Daniel Axtens's Reviewed-by.
> 
>  arch/powerpc/kernel/secure_boot.c | 19 +++++++++++++++++--
>  1 file changed, 17 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/secure_boot.c b/arch/powerpc/kernel/secure_boot.c
> index 4b982324d368..118bcb5f79c4 100644
> --- a/arch/powerpc/kernel/secure_boot.c
> +++ b/arch/powerpc/kernel/secure_boot.c
> @@ -6,6 +6,7 @@
>  #include <linux/types.h>
>  #include <linux/of.h>
>  #include <asm/secure_boot.h>
> +#include <asm/machdep.h>
>  
>  static struct device_node *get_ppc_fw_sb_node(void)
>  {
> @@ -23,12 +24,19 @@ bool is_ppc_secureboot_enabled(void)
>  {
>  	struct device_node *node;
>  	bool enabled = false;
> +	u32 secureboot;
>  
>  	node = get_ppc_fw_sb_node();
>  	enabled = of_property_read_bool(node, "os-secureboot-enforcing");
> -
>  	of_node_put(node);
>  
> +	if (enabled)
> +		goto out;
> +
> +	if (!of_property_read_u32(of_root, "ibm,secure-boot", &secureboot))
> +		enabled = (secureboot > 1);
> +
> +out:
>  	pr_info("Secure boot mode %s\n", enabled ? "enabled" : "disabled");
>  
>  	return enabled;
> @@ -38,12 +46,19 @@ bool is_ppc_trustedboot_enabled(void)
>  {
>  	struct device_node *node;
>  	bool enabled = false;
> +	u32 trustedboot;
>  
>  	node = get_ppc_fw_sb_node();
>  	enabled = of_property_read_bool(node, "trusted-enabled");
> -
>  	of_node_put(node);
>  
> +	if (enabled)
> +		goto out;
> +
> +	if (!of_property_read_u32(of_root, "ibm,trusted-boot", &trustedboot))
> +		enabled = (trustedboot > 0);
> +
> +out:
>  	pr_info("Trusted boot mode %s\n", enabled ? "enabled" : "disabled");
>  
>  	return enabled;
> -- 
> 2.26.2
>