linux-kernel - Re: [PATCH] soc: qcom: socinfo: Open read access to all for debugfs

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Date:   Mon, 11 Jan 2021 18:04:13 -0800
From:   Stephen Boyd <swboyd@...omium.org>
To:     Doug Anderson <dianders@...omium.org>
Cc:     Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        LKML <linux-kernel@...r.kernel.org>,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>,
        Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Subject: Re: [PATCH] soc: qcom: socinfo: Open read access to all for debugfs

Quoting Doug Anderson (2021-01-05 15:06:35)
> Hi,
> 
> On Tue, Dec 15, 2020 at 11:19 PM Stephen Boyd <swboyd@...omium.org> wrote:
> >
> > There doesn't seem to be any reason to limit this to only root user
> > readable. Let's make it readable by all so that random programs can
> > read the debugfs files in here instead of just root. The information is
> > just that, informational, so this is fine.
> >
> > Cc: Sai Prakash Ranjan <saiprakash.ranjan@...eaurora.org>
> > Cc: Douglas Anderson <dianders@...omium.org>
> > Cc: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > Signed-off-by: Stephen Boyd <swboyd@...omium.org>
> > ---
> >  drivers/soc/qcom/socinfo.c | 40 +++++++++++++++++++-------------------
> >  1 file changed, 20 insertions(+), 20 deletions(-)
> 
> One worry I'd have is whether there would ever be any PII (personally
> identifiable information) here, like maybe a chip serial number.  If
> so, is that something that is OK to provide to any random process?
> ...maybe I'm just being paranoid though, since presumably there are
> enough random HW characteristics that could be strung together and
> hashed to make roughly a unique ID anyway and hiding every HW
> characteristic would be a bit extreme...
> 

I suppose if that's a problem then the process that mounts debugfs can
change the access to restrict it. I'm not aware of this needing to be a
kernel policy though, so I'd rather leave that up to userspace to decide
if it should be restricted further.