linux-kernel - Re: [PATCH 09/18] Secure boot: Add a dummy kernel parameter that will switch on Secure Boot mode

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Message-ID: <20130825161649.GF5171@amd.pavel.ucw.cz>
Date:	Sun, 25 Aug 2013 18:16:49 +0200
From:	Pavel Machek <pavel@....cz>
To:	"Lee, Chun-Yi" <joeyli.kernel@...il.com>
Cc:	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, linux-efi@...r.kernel.org,
	linux-pm@...r.kernel.org, linux-crypto@...r.kernel.org,
	opensuse-kernel@...nsuse.org, David Howells <dhowells@...hat.com>,
	"Rafael J. Wysocki" <rjw@...k.pl>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Len Brown <len.brown@...el.com>,
	Josh Boyer <jwboyer@...hat.com>,
	Vojtech Pavlik <vojtech@...e.cz>,
	Matt Fleming <matt.fleming@...el.com>,
	James Bottomley <james.bottomley@...senpartnership.com>,
	Greg KH <gregkh@...uxfoundation.org>, JKosina@...e.com,
	Rusty Russell <rusty@...tcorp.com.au>,
	Herbert Xu <herbert@...dor.apana.org.au>,
	"David S. Miller" <davem@...emloft.net>,
	"H. Peter Anvin" <hpa@...or.com>, Michal Marek <mmarek@...e.cz>,
	Gary Lin <GLin@...e.com>, Vivek Goyal <vgoyal@...hat.com>,
	"Lee, Chun-Yi" <jlee@...e.com>
Subject: Re: [PATCH 09/18] Secure boot: Add a dummy kernel parameter that
 will switch on Secure Boot mode

You may want to check subject. If it does something, it is not dummy.

> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -2784,6 +2784,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>  			Note: increases power consumption, thus should only be
>  			enabled if running jitter sensitive (HPC/RT) workloads.
>  
> +	secureboot_enable=
> +			[KNL] Enables an emulated UEFI Secure Boot mode.  This
> +			locks down various aspects of the kernel guarded by the
> +			CAP_COMPROMISE_KERNEL capability.  This includes things
> +			like /dev/mem, IO port access, and other areas.  It can
> +			be used on non-UEFI machines for testing purposes.
> +
>  	security=	[SECURITY] Choose a security module to enable at boot.
>  			If this boot parameter is not specified, only the first
>  			security module asking for security registration will be
> diff --git a/kernel/cred.c b/kernel/cred.c
> index e0573a4..c3f4e3e 100644
> --- a/kernel/cred.c
> +++ b/kernel/cred.c
> @@ -565,6 +565,23 @@ void __init cred_init(void)
>  				     0, SLAB_HWCACHE_ALIGN|SLAB_PANIC, NULL);
>  }
>  
> +void __init secureboot_enable()
> +{
> +	pr_info("Secure boot enabled\n");
> +	cap_lower((&init_cred)->cap_bset, CAP_COMPROMISE_KERNEL);
> +	cap_lower((&init_cred)->cap_permitted, CAP_COMPROMISE_KERNEL);
> +}

OTOH you don't implement CAP_COMPROMISE_KERNEL, so it is dummy after
all. But CAP_COMPROMISE_KERNEL is infeasible to implement, right?
									Pavel

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