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Violators will be prosecuted for from ; Wed, 27 Feb 2019 15:05:06 -0000 Date: Wed, 27 Feb 2019 12:04:49 -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> <20190226191140.GA25467@kermit.br.ibm.com> <20190226231920.GS6872@umbus.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190226231920.GS6872@umbus.fritz.box> Message-Id: <20190227150449.GA9614@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: David Gibson Cc: "Maxiwell S. Garcia" , "open list:sPAPR" , qemu-devel@nongnu.org Hi, David. On Wed, Feb 27, 2019 at 10:19:20AM +1100, David Gibson wrote: > On Tue, Feb 26, 2019 at 04:11:40PM -0300, Murilo Opsfelder Araujo wrote= : > > On Tue, Feb 26, 2019 at 02:08:30PM -0300, Murilo Opsfelder Araujo wro= te: > > > 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 Arau= jo wrote: > > > > > > Hi, Maxiwell. > > > > > > > > > > > > On Mon, Feb 25, 2019 at 01:23:25PM -0300, Maxiwell S. Garcia = wrote: > > > > > > > This adds a handler for ibm,get-vpd RTAS calls, allowing ps= eries > > > > > > > guest to collect host information. It is disabled by defaul= t 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 land= ed Gibson'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 h= ost if the > > > > > > following combination of parameters are provided: > > > > > > > > > > > > -M host-serial=3Dpassthrough,host-model=3Dpassthrough,vpd-e= xport=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 informa= tion by accident. > > > > > > > > > > > > I'm not even sure if we need vpd-export=3D setting. Its= logic could be > > > > > > derived from the presence of host-serial=3Dpassthrough and ho= st-model=3Dpassthrough > > > > > > options. > > > > > > > > > > > > What do you think? > > > > > > > > > > That's an excellent point - I hadn't thought through the fact t= hat > > > > > this is the same information exposed by those properties. I do= indeed > > > > > think that exposing the same information set in those propertie= s - and > > > > > thereby avoiding the new machine option - would be a better pla= n. > > > > > > > > > > > > > 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 'hos= t-model' > > > > 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 sectio= n "3.3.2.1 > > > Root Node Properties" of the "Device Tree Bindings: Linux on Power = Architecture > > > 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 en= tries): > > > > $ 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-m= odel" > > machine options. > > > > - system-id: created when "-uuid " exists in qemu command line= options. > > > > - model: hard-coded. > > > > With this patch, RTAS ibm,get-vpd call will return "system-id" and "m= odel" from > > the host, not from the guest. I found this confusing. > > Hrm. I found the bit in LoPAPR describing how ibm,get-vpd operates, > but not something describing the actual data that appears within it. > Where's that described? It'd be nice to check if those values are > supposed to be describing the host or the guest. Are you asking about the fields of the ibm,vpd property? They are describ= ed in Table 11.2 "LoPAPR VPD Fields" of this LoPAPR document: https://members.openpowerfoundation.org/wg/SYSSW/document/1461 Is that what you were looking for? > > > > Perhaps we can trick ibm,get-vpd call to return "host-serial" and "ho= st-model" > > values from the guest, which will hold safe values after commit > > 9e584f45868f6945c1282c938278038cba0e4af2 "ppc: add host-serial and ho= st-model > > machine attributes (CVE-2019-8934)". > > Well, if it is supposed to be host values, then yes, absolutely, we > should be using the "host" values that the user supplies (if any). > > > 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. > > > > -- > David Gibson | I'll have my music baroque, and my code > david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _oth= er_ > | _way_ _around_! > http://www.ozlabs.org/~dgibson -- Murilo