Re: [PATCH v7 4/5] efi: Load efi_secret module if EFI secret area is populated

From: Gerd Hoffmann <kraxel@redhat.com>
To: Dov Murik <dovmurik@linux.ibm.com>
Cc: linux-efi@vger.kernel.org, Borislav Petkov <bp@suse.de>,
	Ashish Kalra <ashish.kalra@amd.com>,
	Brijesh Singh <brijesh.singh@amd.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	Ard Biesheuvel <ardb@kernel.org>,
	James Morris <jmorris@namei.org>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Andi Kleen <ak@linux.intel.com>,
	Greg KH <gregkh@linuxfoundation.org>,
	Andrew Scull <ascull@google.com>,
	Dave Hansen <dave.hansen@intel.com>,
	"Dr. David Alan Gilbert" <dgilbert@redhat.com>,
	Lenny Szubowicz <lszubowi@redhat.com>,
	Peter Gonda <pgonda@google.com>,
	James Bottomley <jejb@linux.ibm.com>,
	Tobin Feldman-Fitzthum <tobin@linux.ibm.com>,
	Jim Cadden <jcadden@ibm.com>,
	Daniele Buono <dbuono@linux.vnet.ibm.com>,
	linux-coco@lists.linux.dev,
	linux-security-module@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 4/5] efi: Load efi_secret module if EFI secret area is populated
Date: Wed, 2 Feb 2022 09:47:23 +0100	[thread overview]
Message-ID: <20220202084723.ushasiekb3cxami4@sirius.home.kraxel.org> (raw)
In-Reply-To: <20220201124413.1093099-5-dovmurik@linux.ibm.com>

On Tue, Feb 01, 2022 at 12:44:12PM +0000, Dov Murik wrote:
> If the efi_secret module is built, register a late_initcall in the EFI
> driver which checks whether the EFI secret area is available and
> populated, and then requests to load the efi_secret module.

> +	area = memremap(efi.coco_secret, sizeof(*area), MEMREMAP_WB);
> +	if (!area) {
> +		pr_err("Failed to map confidential computing secret area descriptor\n");
> +		return -ENOMEM;
> +	}
> +	if (!area->base_pa || area->size < sizeof(*header_guid))
> +		goto unmap_desc;
> +
> +	header_guid = (void __force *)ioremap_encrypted(area->base_pa, sizeof(*header_guid));
> +	if (!header_guid) {
> +		pr_err("Failed to map secret area\n");
> +		ret = -ENOMEM;
> +		goto unmap_desc;
> +	}
> +	if (efi_guidcmp(*header_guid, EFI_SECRET_TABLE_HEADER_GUID))
> +		goto unmap_encrypted;

Why these sanity checks are here and not in the efi_secret module?

take care,
  Gerd