linux-kernel - Re: [PATCH v3 0/4] SysFS driver for QEMU fw

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: <20151005124346.GG1977@HEDWIG.INI.CMU.EDU>
Date:	Mon, 5 Oct 2015 08:43:46 -0400
From:	"Gabriel L. Somlo" <somlo@....edu>
To:	Mark Rutland <mark.rutland@....com>
Cc:	Paolo Bonzini <pbonzini@...hat.com>, gregkh@...uxfoundation.org,
	paul@...an.com, galak@...eaurora.org, will.deacon@....com,
	agross@...eaurora.org, zajec5@...il.com, hanjun.guo@...aro.org,
	catalin.marinas@....com, linux-api@...r.kernel.org,
	linux-kernel@...r.kernel.org, kernelnewbies@...nelnewbies.org,
	matt.fleming@...el.com, lersek@...hat.com,
	jordan.l.justen@...el.com, mst@...hat.com,
	peter.maydell@...aro.org, leif.lindholm@...aro.org,
	ard.biesheuvel@...aro.org, kraxel@...hat.com, qemu-devel@...gnu.org
Subject: Re: [PATCH v3 0/4] SysFS driver for QEMU fw_cfg device

On Mon, Oct 05, 2015 at 01:23:33PM +0100, Mark Rutland wrote:
> On Mon, Oct 05, 2015 at 01:48:52PM +0200, Paolo Bonzini wrote:
> > 
> > 
> > On 05/10/2015 12:00, Mark Rutland wrote:
> > > Some of the keys in the example look like they'd come from other sources
> > > (e.g. the *-tables entries), while others look like kernel/bootloader
> > > configuration options (e.g. etc/boot-fail-wait, bootorder) -- I'm
> > > concerned about redundancy here.
> > 
> > The redundancy is because the firmware and the bootloader actually
> > _consume_ these fw_cfg strings to produce the others (the ACPI tables,
> > the kernel configuration options).
> > 
> > On the other hand, hiding some strings just because they ought to have
> > been consumed already makes little sense.
> 
> Sure. However, I'm concerned that providing redundant interfaces for
> those could lead to people grabbing information from here (because it's
> convenient) rather than the existing canonical locations, which means we
> get more software that works on fewer systems for no good reason.
> 
> What I couldn't figure out was what _additional_ information this
> provided; it looked like a mixed bag of details we could already get
> from disparate sources. If that's all it does, then it seems to me like
> it doesn't add any benefit and potentially makes things worse.
> 
> So what do we get from this interface that we cannot get elsewhere, and
> why is this the best way of exposing it?

Starting with qemu 2.4, it is possible to insert arbitrary named
blobs into fw_cfg from the qemu command line. *Those* entries
might be interesting to userspace, which is why it might be handy
to access to fw_cfg blobs in general.

Thanks,
--Gabriel
--
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/