linux-kernel - Re: [PATCH 05/16] iommu/amd: Split device table initialization into irq and dma part

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120928142555.GC4009@amd.com>
Date:	Fri, 28 Sep 2012 16:25:55 +0200
From:	Joerg Roedel <joerg.roedel@....com>
To:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
CC:	<iommu@...ts.linux-foundation.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 05/16] iommu/amd: Split device table initialization into
 irq and dma part

On Fri, Sep 28, 2012 at 10:17:53AM -0400, Konrad Rzeszutek Wilk wrote:
> On Fri, Sep 28, 2012 at 02:23:55PM +0200, Joerg Roedel wrote:
> > When the IOMMU is enabled very early (as with irq-remapping)
> > some devices are still in BIOS hand. When dma is blocked
> > early this can cause lots of IO_PAGE_FAULTs. So delay the
> > DMA initialization and do it right before the dma_ops are
> > initialized.
> > To be secure, block all interrupts by default when irq-remapping is
> 
> What are you trying to be secure against?

Against attacks of faked MSI msgs that could DoS the system. MSI
messages are only specific DMA transactions in the end and a guest with
a device assigned has control over its DMA engine and can thus send
arbitrary interrupt requests to the host. There is a whole paper about
such attacks. I can't find right now, but I send you  a link when I find
it.

	Joerg

-- 
AMD Operating System Research Center

Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach
General Managers: Alberto Bozzo
Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/