linux-kernel - Re: [RFCv1 0/6] Page Detective

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Message-ID: <CA+CK2bD4zcXVATVhcUHBsA7Adtmh9LzCStWRDQyo_DsXxTOahA@mail.gmail.com>
Date: Tue, 19 Nov 2024 14:30:10 -0500
From: Pasha Tatashin <pasha.tatashin@...een.com>
To: Roman Gushchin <roman.gushchin@...ux.dev>
Cc: Greg KH <gregkh@...uxfoundation.org>, linux-kernel@...r.kernel.org, 
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Subject: Re: [RFCv1 0/6] Page Detective

On Tue, Nov 19, 2024 at 1:23 PM Roman Gushchin <roman.gushchin@...ux.dev> wrote:
>
> On Tue, Nov 19, 2024 at 10:08:36AM -0500, Pasha Tatashin wrote:
> > On Mon, Nov 18, 2024 at 8:09 PM Greg KH <gregkh@...uxfoundation.org> wrote:
> > >
> > > On Mon, Nov 18, 2024 at 05:08:42PM -0500, Pasha Tatashin wrote:
> > > > Additionally, using crash/drgn is not feasible for us at this time, it
> > > > requires keeping external tools on our hosts, also it requires
> > > > approval and a security review for each script before deployment in
> > > > our fleet.
> > >
> > > So it's ok to add a totally insecure kernel feature to your fleet
> > > instead?  You might want to reconsider that policy decision :)
> >
> > Hi Greg,
> >
> > While some risk is inherent, we believe the potential for abuse here
> > is limited, especially given the existing  CAP_SYS_ADMIN requirement.
> > But, even with root access compromised, this tool presents a smaller
> > attack surface than alternatives like crash/drgn. It exposes less
> > sensitive information, unlike crash/drgn, which could potentially
> > allow reading all of kernel memory.
>
> The problem here is with using dmesg for output. No security-sensitive
> information should go there. Even exposing raw kernel pointers is not
> considered safe.

I am OK in writing the output to a debugfs file in the next version,
the only concern I have is that implies that dump_page() would need to
be basically duplicated, as it now outputs everything via printk's.