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From: Mark Rutland <mark.rutland@arm.com>
To: David Howells <dhowells@redhat.com>
Cc: lukas@wunner.de, linux-efi@vger.kernel.org,
	linux-security-module@vger.kernel.org, keyrings@vger.kernel.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 4/6] efi: Get the secure boot status [ver #2]
Date: Wed, 23 Nov 2016 10:47:58 +0000	[thread overview]
Message-ID: <20161123104757.GE24624@leverpostej> (raw)
In-Reply-To: <147986057768.13790.3027173260868896792.stgit@warthog.procyon.org.uk>

On Wed, Nov 23, 2016 at 12:22:57AM +0000, David Howells wrote:
> @@ -1158,6 +1158,8 @@ struct boot_params *efi_main(struct efi_config *c,
>  	else
>  		setup_boot_services32(efi_early);
>  
> +	boot_params->secure_boot = (efi_get_secureboot(sys_table) == 1);

In the arm stub's efi_entry(), we fail-safe, and assume secure boot for any
non-zero status (including errors). e.g. 

	secure_boot = efi_get_secureboot(sys_table);
	if (secure_boot > 0)
		pr_efi(sys_table, "UEFI Secure Boot is enabled.\n");

	if (secure_boot < 0) {
		pr_efi_err(sys_table,
			"could not determine UEFI Secure Boot status.\n");
	}

	/*
	 * Unauthenticated device tree data is a security hazard, so
	 * ignore 'dtb=' unless UEFI Secure Boot is disabled.
	 */
	if (secure_boot != 0 && strstr(cmdline_ptr, "dtb=")) {
		pr_efi(sys_table, "Ignoring DTB from command line.\n");

... should we not do likewise here, e.g.

	int secure_boot = efi_get_secureboot(sys_table);

	if (secure_boot > 0)
		pr_efi(sys_table, "UEFI Secure Boot is enabled.\n");
	if (secure_boot < 0)
		pr_efi_err(sys_table,
			"could not determine UEFI Secure Boot status.\n");

	/*
	 * Fail-safe in the case of an error determining the secure boot
	 * status.
	 */
	boot_params->secure_boot = (secure_boot != 0);

... ?

Thanks,
Mark.

  parent reply	other threads:[~2016-11-23 10:48 UTC|newest]

Thread overview: 28+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-11-23  0:22 [PATCH 0/6] efi: Pass secure boot mode to kernel [ver #2] David Howells
2016-11-23  0:22 ` [PATCH 1/6] x86/efi: Allow invocation of arbitrary runtime services " David Howells
2016-11-23  0:22 ` [PATCH 2/6] arm/efi: " David Howells
2016-11-23  9:34   ` David Howells
2016-11-23 10:35     ` Ard Biesheuvel
2016-11-23 11:51       ` David Howells
2016-11-23 10:27   ` Mark Rutland
2016-11-23 11:46     ` David Howells
2016-11-23 13:38       ` Mark Rutland
2016-11-23  0:22 ` [PATCH 3/6] efi: Add SHIM and image security database GUID definitions " David Howells
2016-11-23  0:22 ` [PATCH 4/6] efi: Get the secure boot status " David Howells
2016-11-23  9:31   ` Lukas Wunner
2016-11-23  9:53     ` David Howells
2016-11-23 10:10       ` Lukas Wunner
2016-11-23 10:47   ` Mark Rutland [this message]
2016-11-23 11:25     ` David Howells
2016-11-23 13:42       ` Mark Rutland
2016-11-23 14:13         ` David Howells
2016-11-23 14:24           ` Mark Rutland
2016-11-23 14:55             ` David Howells
2016-11-29 18:11               ` Matthew Garrett
2016-11-30 16:51     ` David Howells
2016-11-23  0:23 ` [PATCH 5/6] efi: Disable secure boot if shim is in insecure mode " David Howells
2016-11-23 13:38   ` Mark Rutland
2016-11-23  0:23 ` [PATCH 6/6] efi: Add EFI_SECURE_BOOT bit " David Howells
2016-11-23  9:27   ` Lukas Wunner
2016-11-23 10:07     ` David Howells
2016-11-23 10:09       ` David Howells

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