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From: "H. Peter Anvin" <hpa@zytor.com>
To: Matthew Garrett <matthew.garrett@nebula.com>
Cc: linux-pci@vger.kernel.org, linux-security-module@vger.kernel.org,
	linux-efi@vger.kernel.org, kexec@lists.infradead.org,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH 01/12] Security: Add CAP_COMPROMISE_KERNEL
Date: Tue, 19 Mar 2013 18:02:53 -0700	[thread overview]
Message-ID: <51490ABD.3050205@zytor.com> (raw)
In-Reply-To: <1363642353-30749-1-git-send-email-matthew.garrett@nebula.com>

On 03/18/2013 02:32 PM, Matthew Garrett wrote:
> 
> This means we can return our focus to the kernel. There's currently a number
> of kernel interfaces that permit privileged userspace to modify the running
> kernel. These are currently protected by CAP_SYS_RAWIO, but unfortunately
> the semantics of this capability are poorly defined and it now covers a large
> superset of the desired behaviour.
> 

... except it doesn't.

Looking at it in detail, EVERYTHING in CAP_SYS_RAWIO has the possibility
of compromising the kernel, because they let device drivers be bypassed,
which means arbitrary DMA, which means you have everything.

Now, a lot of the abuses of CAP_SYS_RAWIO have clearly been added by
people who had *no bloody clue* what that capability meant, but it
really doesn't change the fact that pretty much if you have
CAP_SYS_RAWIO you have the machine.

So just reject CAP_SYS_RAWIO.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.


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  parent reply	other threads:[~2013-03-20  1:03 UTC|newest]

Thread overview: 54+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-03-18 21:32 [PATCH 01/12] Security: Add CAP_COMPROMISE_KERNEL Matthew Garrett
2013-03-18 21:32 ` [PATCH 02/12] SELinux: define mapping for CAP_COMPROMISE_KERNEL Matthew Garrett
2013-03-18 21:32 ` [PATCH 03/12] Secure boot: Add a dummy kernel parameter that will switch on Secure Boot mode Matthew Garrett
2013-03-18 21:32 ` [PATCH 04/12] efi: Enable secure boot lockdown automatically when enabled in firmware Matthew Garrett
2013-03-18 21:32 ` [PATCH 05/12] PCI: Require CAP_COMPROMISE_KERNEL for PCI BAR access Matthew Garrett
2013-03-27 15:03   ` Josh Boyer
2013-03-27 15:08     ` Kyle McMartin
2013-03-28 12:46       ` Josh Boyer
2013-03-18 21:32 ` [PATCH 06/12] x86: Require CAP_COMPROMISE_KERNEL for IO port access Matthew Garrett
2013-03-20  1:00   ` H. Peter Anvin
2013-03-18 21:32 ` [PATCH 07/12] ACPI: Limit access to custom_method Matthew Garrett
2013-03-18 21:32 ` [PATCH 08/12] asus-wmi: Restrict debugfs interface Matthew Garrett
2013-03-18 21:32 ` [PATCH 09/12] Require CAP_COMPROMISE_KERNEL for /dev/mem and /dev/kmem access Matthew Garrett
2013-03-18 21:32 ` [PATCH 10/12] acpi: Ignore acpi_rsdp kernel parameter in a secure boot environment Matthew Garrett
2013-03-19  8:47   ` Dave Young
2013-03-19 11:19     ` Josh Boyer
2013-03-19 17:07       ` [PATCH v2] " Josh Boyer
2013-03-18 21:32 ` [PATCH 11/12] x86: Require CAP_COMPROMISE_KERNEL for MSR writing Matthew Garrett
2013-03-18 21:32 ` [PATCH 12/12] kexec: Require CAP_SYS_COMPROMISE_KERNEL Matthew Garrett
2013-03-19  4:47 ` [PATCH 01/12] Security: Add CAP_COMPROMISE_KERNEL James Morris
2013-03-20  1:03   ` H. Peter Anvin
2013-03-20 16:41   ` Mimi Zohar
2013-03-20 16:49     ` Matthew Garrett
2013-03-20 18:01       ` Mimi Zohar
2013-03-20 18:12         ` Matthew Garrett
2013-03-20 19:16           ` Mimi Zohar
2013-03-20 20:37             ` Matthew Garrett
2013-03-20 21:11               ` Mimi Zohar
2013-03-20 21:18                 ` Matthew Garrett
2013-03-21 13:43                   ` Vivek Goyal
2013-03-21 15:37                     ` Serge E. Hallyn
2013-03-21 15:52                       ` Vivek Goyal
2013-03-21 15:58                         ` Serge E. Hallyn
2013-03-21 16:04                           ` Vivek Goyal
2013-03-21 16:19                             ` Serge E. Hallyn
2013-03-21 17:15                               ` Vivek Goyal
2013-03-21  1:58     ` James Morris
2013-03-19  7:18 ` Yves-Alexis Perez
2013-03-20  1:02 ` H. Peter Anvin [this message]
2013-03-20  1:05   ` H. Peter Anvin
2013-03-20 13:15   ` Matthew Garrett
2013-03-20 15:03     ` H. Peter Anvin
2013-03-20 15:14       ` Matthew Garrett
2013-03-20 16:45         ` H. Peter Anvin
  -- strict thread matches above, loose matches on Subject: below --
2013-03-20  1:07 Matthew Garrett
2013-03-20  1:11 ` H. Peter Anvin
2013-03-20  1:09 Matthew Garrett
2013-03-20  1:28 Matthew Garrett
2013-03-20  2:48 ` H. Peter Anvin
2013-03-20  3:08   ` H. Peter Anvin
2013-03-20  3:18     ` Alex Williamson
2013-03-20  3:22       ` H. Peter Anvin
2013-03-20  3:27         ` Alex Williamson
2013-03-21 16:32 Matthew Garrett

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