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Date:   Thu, 30 Sep 2021 11:59:04 -0400
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     Alan Stern <stern@rowland.harvard.edu>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Kuppuswamy Sathyanarayanan 
        <sathyanarayanan.kuppuswamy@linux.intel.com>,
        Borislav Petkov <bp@alien8.de>, x86@kernel.org,
        Bjorn Helgaas <bhelgaas@google.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Ingo Molnar <mingo@redhat.com>,
        Andreas Noever <andreas.noever@gmail.com>,
        Michael Jamet <michael.jamet@intel.com>,
        Yehezkel Bernat <YehezkelShB@gmail.com>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Jonathan Corbet <corbet@lwn.net>,
        Jason Wang <jasowang@redhat.com>,
        Dan Williams <dan.j.williams@intel.com>,
        Andi Kleen <ak@linux.intel.com>,
        Kuppuswamy Sathyanarayanan <knsathya@kernel.org>,
        linux-kernel@vger.kernel.org, linux-pci@vger.kernel.org,
        linux-usb@vger.kernel.org,
        virtualization@lists.linux-foundation.org
Subject: Re: [PATCH v2 2/6] driver core: Add common support to skip probe for
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On Thu, Sep 30, 2021 at 11:35:09AM -0400, Alan Stern wrote:
> On Thu, Sep 30, 2021 at 10:58:07AM -0400, Michael S. Tsirkin wrote:
> > On Thu, Sep 30, 2021 at 10:43:05AM -0400, Alan Stern wrote:
> > > I don't see any point in talking about "untrusted drivers".  If a 
> > > driver isn't trusted then it doesn't belong in your kernel.  Period.  
> > > When you load a driver into your kernel, you are implicitly trusting 
> > > it (aside from limitations imposed by security modules).
> > 
> > Trusting it to do what? Historically a ton of drivers did not
> > validate input from devices they drive. Most still don't.
> 
> Trusting it to behave properly (i.e., not destroy your system, among 
> other things).

I don't think the current mitigations under discussion here are about
keeping the system working. In fact most encrypted VM configs tend to
stop booting as a preferred way to handle security issues.

> The fact that many drivers haven't been trustworthy is beside the 
> point.  By loading them into your kernel, you are trusting them 
> regardless.  In the end, you may regret having done so.  :-(
> 
> Alan Stern


-- 
MST