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Violators will be prosecuted for from ; Tue, 26 Feb 2019 19:11:44 -0000 Date: Tue, 26 Feb 2019 16:11:40 -0300 From: Murilo Opsfelder Araujo References: <20190225162325.24008-1-maxiwell@linux.ibm.com> <20190225232009.GB30778@kermit.br.ibm.com> <20190226032103.GJ6872@umbus.fritz.box> <20190226142126.jxosththzad6h6dd@maxibm> <20190226170830.GA16569@kermit.br.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190226170830.GA16569@kermit.br.ibm.com> Message-Id: <20190226191140.GA25467@kermit.br.ibm.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [Qemu-ppc] [PATCH v2] spapr-rtas: add ibm, get-vpd RTAS interface List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Maxiwell S. Garcia" Cc: "open list:sPAPR" , qemu-devel@nongnu.org, David Gibson On Tue, Feb 26, 2019 at 02:08:30PM -0300, Murilo Opsfelder Araujo wrote: > Hi, Maxiwell. > > On Tue, Feb 26, 2019 at 11:21:26AM -0300, Maxiwell S. Garcia wrote: > > On Tue, Feb 26, 2019 at 02:21:03PM +1100, David Gibson wrote: > > > On Mon, Feb 25, 2019 at 08:20:09PM -0300, Murilo Opsfelder Araujo w= rote: > > > > Hi, Maxiwell. > > > > > > > > On Mon, Feb 25, 2019 at 01:23:25PM -0300, Maxiwell S. Garcia wrot= e: > > > > > This adds a handler for ibm,get-vpd RTAS calls, allowing pserie= s > > > > > guest to collect host information. It is disabled by default to > > > > > avoid unwanted information leakage. To enable it, use: > > > > > =E2=80=98-M pseries,vpd-export=3Don=E2=80=99 > > > > > > > > The patch for setting host-serial and host-model already landed G= ibson's > > > > ppc-for-4.0 branch: > > > > > > > > commit 9e584f45868f6945c1282c938278038cba0e4af2 > > > > Author: Prasad J Pandit > > > > Date: Mon Feb 18 23:43:49 2019 +0530 > > > > > > > > ppc: add host-serial and host-model machine attributes (CVE= -2019-8934) > > > > > > > > > > > > QEMU should only return host-serial and host-model from the host = if the > > > > following combination of parameters are provided: > > > > > > > > -M host-serial=3Dpassthrough,host-model=3Dpassthrough,vpd-expor= t=3Don > > > > > > > > If host-serial or host-model are set with a user-string, ibm,get-= vpd should > > > > honor these values and return them, not exposing host information= by accident. > > > > > > > > I'm not even sure if we need vpd-export=3D setting. Its log= ic could be > > > > derived from the presence of host-serial=3Dpassthrough and host-m= odel=3Dpassthrough > > > > options. > > > > > > > > What do you think? > > > > > > That's an excellent point - I hadn't thought through the fact that > > > this is the same information exposed by those properties. I do ind= eed > > > think that exposing the same information set in those properties - = and > > > thereby avoiding the new machine option - would be a better plan. > > > > > > > I saw that the patch was applied. So I will work in another patch > > to use these properties and remove the export-vpd option. > > > > Another thing that I thought the fact that 'host-serial' and 'host-mo= del' > > nodes in Device Tree are not in accordance with LoPAPR document. What > > you think in use only get-vpd to get these information and remove > > nodes from device tree? > > Both "system-id" and "model" properties are described in the section "3= .3.2.1 > Root Node Properties" of the "Device Tree Bindings: Linux on Power Arch= itecture > Reference" document: > > https://members.openpowerfoundation.org/wg/SYSSW/document/1455 I replied too early. As Maxiwell explained to me (thanks Max!), guest can= end up having the following entries under /proc/device-tree/ (among other entrie= s): $ cat host-serial 12A3B4C $ cat host-model 1234-56A $ cat system-id c7b62da9-3d0c-44f9-8edb-2318271f3c1a $ cat model IBM pSeries (emulated by qemu) Where: - host-serial/host-model: depend on "-M host-serial" and "-M host-model= " machine options. - system-id: created when "-uuid " exists in qemu command line opt= ions. - model: hard-coded. With this patch, RTAS ibm,get-vpd call will return "system-id" and "model= " from the host, not from the guest. I found this confusing. Perhaps we can trick ibm,get-vpd call to return "host-serial" and "host-m= odel" values from the guest, which will hold safe values after commit 9e584f45868f6945c1282c938278038cba0e4af2 "ppc: add host-serial and host-m= odel machine attributes (CVE-2019-8934)". What do you think? As to removing "host-serial" and "host-model", I am not entirely sure for= what they are used. There should be a reason for them to exist. -- Murilo