From: David Howells <dhowells@redhat.com>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: James Bottomley <James.Bottomley@hansenpartnership.com>,
"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
dhowells@redhat.com,
linux-security-module <linux-security-module@vger.kernel.org>,
Lukas Wunner <lukas@wunner.de>,
keyrings@vger.kernel.org,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 5/7] efi: Get the secure boot status [ver #3]
Date: Fri, 25 Nov 2016 12:35:03 +0000 [thread overview]
Message-ID: <17565.1480077303@warthog.procyon.org.uk> (raw)
In-Reply-To: <CAKv+Gu_d5+Kvo7Tptnpg7kfjpqxhQ3a3nsQ0Ufsm6rBOFry+mQ@mail.gmail.com>
Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> Yes. In pre-2.6, DeployedMode is not a reserved name, and so it may be
> possible for someone to slip in a DeployedMode=0 on a secure boot
> enabled system to trick the kernel into thinking lockdown should be
> disabled.
How does one get the version number? Unfortunately, searching the document
for 'version' doesn't help as every page has that in the footer:-/
> > + if (val == 1)
> > + return 0;
>
> I think the logic is the wrong way around here. Secure Boot is enabled
> if SecureBoot=1 and SetupMode=0, unless DeployedMode=0. So you should
> return 0 here if val == 0, but only when running on 2.6 or later.
Good point.
David
WARNING: multiple messages have this Message-ID (diff)
From: dhowells@redhat.com (David Howells)
To: linux-arm-kernel@lists.infradead.org
Subject: [PATCH 5/7] efi: Get the secure boot status [ver #3]
Date: Fri, 25 Nov 2016 12:35:03 +0000 [thread overview]
Message-ID: <17565.1480077303@warthog.procyon.org.uk> (raw)
In-Reply-To: <CAKv+Gu_d5+Kvo7Tptnpg7kfjpqxhQ3a3nsQ0Ufsm6rBOFry+mQ@mail.gmail.com>
Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> Yes. In pre-2.6, DeployedMode is not a reserved name, and so it may be
> possible for someone to slip in a DeployedMode=0 on a secure boot
> enabled system to trick the kernel into thinking lockdown should be
> disabled.
How does one get the version number? Unfortunately, searching the document
for 'version' doesn't help as every page has that in the footer:-/
> > + if (val == 1)
> > + return 0;
>
> I think the logic is the wrong way around here. Secure Boot is enabled
> if SecureBoot=1 and SetupMode=0, unless DeployedMode=0. So you should
> return 0 here if val == 0, but only when running on 2.6 or later.
Good point.
David
WARNING: multiple messages have this Message-ID (diff)
From: David Howells <dhowells@redhat.com>
To: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Cc: dhowells@redhat.com,
James Bottomley <James.Bottomley@hansenpartnership.com>,
"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
linux-security-module <linux-security-module@vger.kernel.org>,
Lukas Wunner <lukas@wunner.de>,
keyrings@vger.kernel.org,
"linux-arm-kernel@lists.infradead.org"
<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCH 5/7] efi: Get the secure boot status [ver #3]
Date: Fri, 25 Nov 2016 12:35:03 +0000 [thread overview]
Message-ID: <17565.1480077303@warthog.procyon.org.uk> (raw)
In-Reply-To: <CAKv+Gu_d5+Kvo7Tptnpg7kfjpqxhQ3a3nsQ0Ufsm6rBOFry+mQ@mail.gmail.com>
Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> Yes. In pre-2.6, DeployedMode is not a reserved name, and so it may be
> possible for someone to slip in a DeployedMode=0 on a secure boot
> enabled system to trick the kernel into thinking lockdown should be
> disabled.
How does one get the version number? Unfortunately, searching the document
for 'version' doesn't help as every page has that in the footer:-/
> > + if (val == 1)
> > + return 0;
>
> I think the logic is the wrong way around here. Secure Boot is enabled
> if SecureBoot=1 and SetupMode=0, unless DeployedMode=0. So you should
> return 0 here if val == 0, but only when running on 2.6 or later.
Good point.
David
next prev parent reply other threads:[~2016-11-25 12:35 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-23 12:53 [PATCH 0/7] efi: Pass secure boot mode to kernel [ver #3] David Howells
2016-11-23 12:53 ` David Howells
[not found] ` <147990561294.7576.6464430479448167484.stgit-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-23 12:53 ` [PATCH 1/7] efi: use typed function pointers for runtime services table " David Howells
2016-11-23 12:53 ` David Howells
2016-11-23 12:53 ` David Howells
2016-11-23 12:54 ` [PATCH 4/7] efi: Add SHIM and image security database GUID definitions " David Howells
2016-11-23 12:54 ` David Howells
2016-11-23 12:54 ` David Howells
2016-11-23 12:53 ` [PATCH 2/7] x86/efi: Allow invocation of arbitrary runtime services " David Howells
2016-11-23 12:53 ` David Howells
2016-11-23 12:53 ` [PATCH 3/7] arm/efi: " David Howells
2016-11-23 12:53 ` David Howells
2016-11-23 12:54 ` [PATCH 5/7] efi: Get the secure boot status " David Howells
2016-11-23 12:54 ` David Howells
[not found] ` <147990565051.7576.9673287945782426886.stgit-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-24 19:41 ` James Bottomley
2016-11-24 19:41 ` James Bottomley
2016-11-24 19:41 ` James Bottomley
2016-11-25 9:30 ` David Howells
2016-11-25 9:30 ` David Howells
2016-11-25 9:30 ` David Howells
[not found] ` <15173.1480066220-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-25 9:52 ` Ard Biesheuvel
2016-11-25 9:52 ` Ard Biesheuvel
2016-11-25 9:52 ` Ard Biesheuvel
[not found] ` <CAKv+Gu_JxNLDjaK5jGbX9ACzM0uHJYMOFx7XDo4t7DtBMtFRGA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-11-25 12:03 ` David Howells
2016-11-25 12:03 ` David Howells
2016-11-25 12:03 ` David Howells
[not found] ` <16661.1480075392-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-25 12:24 ` Ard Biesheuvel
2016-11-25 12:24 ` Ard Biesheuvel
2016-11-25 12:24 ` Ard Biesheuvel
2016-11-25 12:35 ` David Howells [this message]
2016-11-25 12:35 ` David Howells
2016-11-25 12:35 ` David Howells
2016-11-25 12:43 ` Ard Biesheuvel
2016-11-25 12:43 ` Ard Biesheuvel
2016-11-25 12:51 ` David Howells
2016-11-25 12:51 ` David Howells
2016-11-25 12:51 ` David Howells
2016-11-25 12:52 ` Ard Biesheuvel
2016-11-25 12:52 ` Ard Biesheuvel
2016-11-25 12:52 ` Ard Biesheuvel
[not found] ` <CAKv+Gu9c-C2uXZ0fVatCM8ffXJZDgjBcDb_T0nsFecGqgrF11Q-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2016-11-25 13:00 ` David Howells
2016-11-25 13:00 ` David Howells
2016-11-25 13:00 ` David Howells
[not found] ` <31374.1480078855-S6HVgzuS8uM4Awkfq6JHfwNdhmdF6hFW@public.gmane.org>
2016-11-25 13:50 ` Ard Biesheuvel
2016-11-25 13:50 ` Ard Biesheuvel
2016-11-25 13:50 ` Ard Biesheuvel
2016-11-25 15:59 ` David Howells
2016-11-25 15:59 ` David Howells
2016-11-25 16:50 ` David Howells
2016-11-25 16:50 ` David Howells
2016-11-25 16:50 ` David Howells
2016-11-25 16:51 ` Ard Biesheuvel
2016-11-25 16:51 ` Ard Biesheuvel
2016-11-25 16:57 ` David Howells
2016-11-25 16:57 ` David Howells
2016-11-23 12:54 ` [PATCH 6/7] efi: Disable secure boot if shim is in insecure mode " David Howells
2016-11-23 12:54 ` David Howells
2016-11-23 12:54 ` [PATCH 7/7] efi: Add EFI_SECURE_BOOT bit " David Howells
2016-11-23 12:54 ` David Howells
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