linux-kernel - Re: [PATCH v2 2/4] firmware: qcom: uefisecapp: add support for R/O UEFI vars

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: <cae5bfbe-9537-4b9d-b026-170063054b35@oss.qualcomm.com>
Date: Thu, 26 Jun 2025 15:49:32 +0200
From: Konrad Dybcio <konrad.dybcio@....qualcomm.com>
To: Johan Hovold <johan@...nel.org>,
        Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>,
        Maximilian Luz <luzmaximilian@...il.com>,
        Konrad Dybcio <konradybcio@...nel.org>, Rob Herring <robh@...nel.org>,
        Krzysztof Kozlowski <krzk+dt@...nel.org>,
        Conor Dooley
 <conor+dt@...nel.org>, linux-arm-msm@...r.kernel.org,
        linux-kernel@...r.kernel.org, devicetree@...r.kernel.org
Subject: Re: [PATCH v2 2/4] firmware: qcom: uefisecapp: add support for R/O
 UEFI vars

On 6/26/25 3:13 PM, Johan Hovold wrote:
> On Thu, Jun 26, 2025 at 02:15:26PM +0300, Dmitry Baryshkov wrote:
>> On Thu, Jun 26, 2025 at 11:42:50AM +0200, Johan Hovold wrote:
>>> On Tue, Jun 24, 2025 at 04:13:34AM +0300, Dmitry Baryshkov wrote:
>>>> On Mon, Jun 23, 2025 at 04:50:27PM +0200, Johan Hovold wrote:
>>>>> On Mon, Jun 23, 2025 at 04:45:30PM +0200, Johan Hovold wrote:
>>>
>>>>>> Also not sure how useful it is to only be able to read variables,
>>>>>> including for the RTC where you'll end up with an RTC that's always
>>>>>> slightly off due to drift (even if you can set it when booting into
>>>>>> Windows or possibly from the UEFI setup).
>>>>>>
>>>>>> Don't you have any SDAM blocks in the PMICs that you can use instead for
>>>>>> a proper functioning RTC on these machines?
>>>>
>>>> I'd rather not poke into an SDAM, especially since we don't have docs
>>>> which SDAM blocks are used and which are not.
>>>
>>> You're with Qualcomm now so you should be able to dig up this
>>> information like we did for the X13s (even if I'm quite aware that it
>>> may still be easier said than done).
>>
>> I'd rather try to find information on how to update UEFI vars on the
>> storage.
> 
> You can do both, especially if it turns out you won't be able to have
> persistent variables on these machines.

The danger here is that we only know what Qualcomm uses these cells
for, not necessarily what the vendors with a similar idea could
have come up with.

This is especially important since (unfortunately without going into
detail), you *really* don't want to mess up some existing values in
there.

Konrad