Re: [PATCH 00/12] One more attempt at useful kernel lockdown

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From: Matthew Garrett <matthew.garrett@nebula.com>
To: David Lang <david@lang.hm>
Cc: "Valdis.Kletnieks@vt.edu" <Valdis.Kletnieks@vt.edu>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"keescook@chromium.org" <keescook@chromium.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"hpa@zytor.com" <hpa@zytor.com>,
	"linux-efi@vger.kernel.org" <linux-efi@vger.kernel.org>,
	"jmorris@namei.org" <jmorris@namei.org>,
	"linux-security-module@vger.kernel.org" 
	<linux-security-module@vger.kernel.org>
Subject: Re: [PATCH 00/12] One more attempt at useful kernel lockdown
Date: Mon, 9 Sep 2013 23:02:05 +0000	[thread overview]
Message-ID: <1378767723.17982.27.camel@x230.lan> (raw)
In-Reply-To: <alpine.DEB.2.02.1309091119330.2479@nftneq.ynat.uz>

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On Mon, 2013-09-09 at 11:25 -0700, David Lang wrote:

> 1 lock down modules
> 2 lock down kexec

Having thought about this, the answer is no. It presents exactly the
same problem as capabilities do - the set can never be meaningfully
extended. If an application sets only the bits it knows about, and if a
new security-sensitive feature is added to the kernel, the feature will
be left enabled and the system will be insecure. Alternatively, if an
application sets all the bits regardless of whether it knows them or
not, it may enable a lockdown feature that it otherwise required.

The only way this is useful is if all the bits are semantically
equivalent, and in that case there's no point in having anything other
than a single bit. Users who want a more fine-grained interface should
use one of the existing mechanisms for doing so - leave the kernel open
and impose the security policy from userspace using either capabilities
or selinux.

-- 
Matthew Garrett <matthew.garrett@nebula.com>
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next prev parent reply	other threads:[~2013-09-09 23:02 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-09-09 15:49 Matthew Garrett
2013-09-09 15:49 ` [PATCH 01/12] Add BSD-style securelevel support Matthew Garrett
2013-09-09 16:27   ` H. Peter Anvin
2013-09-09 16:30     ` Matthew Garrett
2013-09-09 16:42       ` H. Peter Anvin
2013-09-09 16:44         ` Matthew Garrett
2013-09-09 16:51           ` H. Peter Anvin
2013-09-09 16:55             ` Matthew Garrett
2013-09-09 18:31     ` Matthew Garrett
2013-09-09 15:49 ` [PATCH 02/12] Enforce module signatures when securelevel is greater than 0 Matthew Garrett
2013-09-09 15:49 ` [PATCH 03/12] PCI: Lock down BAR access when securelevel is enabled Matthew Garrett
2013-09-09 15:49 ` [PATCH 04/12] x86: Lock down IO port " Matthew Garrett
2013-09-09 15:49 ` [PATCH 05/12] Restrict /dev/mem and /dev/kmem when securelevel is set Matthew Garrett
2013-09-09 15:49 ` [PATCH 06/12] acpi: Limit access to custom_method if " Matthew Garrett
2013-09-09 15:49 ` [PATCH 07/12] acpi: Ignore acpi_rsdp kernel parameter when " Matthew Garrett
2013-11-26 12:54   ` Josh Boyer
2013-09-09 15:49 ` [PATCH 08/12] kexec: Disable at runtime if securelevel has been set Matthew Garrett
2013-09-09 15:49 ` [PATCH 09/12] uswsusp: Disable when securelevel is set Matthew Garrett
2013-09-09 15:49 ` [PATCH 10/12] x86: Restrict MSR access " Matthew Garrett
2013-09-09 15:49 ` [PATCH 11/12] asus-wmi: Restrict debugfs interface " Matthew Garrett
2013-09-09 15:49 ` [PATCH 12/12] Add option to automatically set securelevel when in Secure Boot mode Matthew Garrett
2013-09-09 17:18 ` [PATCH 00/12] One more attempt at useful kernel lockdown Valdis.Kletnieks
2013-09-09 17:24   ` Matthew Garrett
2013-09-09 18:25   ` David Lang
2013-09-09 18:28     ` Matthew Garrett
2013-09-09 18:40       ` David Lang
2013-09-09 18:42         ` Matthew Garrett
2013-09-09 18:53           ` David Lang
2013-09-09 19:06             ` Matthew Garrett
2013-09-09 19:59               ` David Lang
2013-09-09 20:06                 ` Matthew Garrett
2013-09-09 20:15                   ` David Lang
2013-09-09 20:17                     ` Matthew Garrett
2013-09-09 19:01     ` Valdis.Kletnieks
2013-09-09 19:08       ` Matthew Garrett
2013-09-09 19:41       ` H. Peter Anvin
2013-09-09 19:52         ` Josh Boyer
2013-09-09 19:56           ` H. Peter Anvin
2013-09-09 19:58             ` Josh Boyer
2013-09-09 20:02               ` H. Peter Anvin
2013-09-09 20:10           ` David Lang
2013-09-09 20:13             ` Josh Boyer
2013-09-09 23:02     ` Matthew Garrett [this message]
2013-09-09 23:19       ` David Lang
2013-09-09 23:20         ` Kees Cook
2013-09-09 23:30           ` James Bottomley
2013-09-09 23:34             ` Kees Cook
2013-09-10  0:53         ` Matthew Garrett
2013-09-10  2:44           ` David Lang
2013-09-10  2:55             ` Matthew Garrett
2013-09-10  3:09               ` David Lang
2013-09-10  3:53                 ` Matthew Garrett
2013-09-10 17:23                   ` Henrique de Moraes Holschuh
2013-09-10 18:26                     ` Matthew Garrett
2013-09-10 18:29                       ` H. Peter Anvin
2013-09-10 18:51                         ` gregkh
2013-09-10 18:55                           ` Kees Cook
2013-09-10 19:17                             ` David Lang
2013-09-10 19:44                               ` H. Peter Anvin
2013-09-10 23:43                                 ` Mimi Zohar
2013-09-10 23:48                                   ` H. Peter Anvin
2013-09-10 23:55                                     ` Mimi Zohar
2013-09-10 23:58                                       ` H. Peter Anvin
2013-09-10 18:48                       ` Kees Cook
2013-09-11  9:32                       ` joeyli
2013-09-09 20:30 ` Mimi Zohar

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