* Ingo Molnar <mi...@kernel.org> wrote:
>
> * H. Peter Anvin <h...@zytor.com> wrote:
>
> > On 01/26/2014 10:49 PM, Richard Weinberger wrote:
> > >>
> > >> No, because that information is available to user space unless we panic.
> > >
> > > Didn't you mean non-root?
> > > I thought one has to set dmesg_restrict anyways if kASLR is used.
> > >
> > > And isn't the offset available to perf too?
> > > Of course only for root, but still user space.
> > >
> >
> > For certain system security levels one want to protect even from a
> > rogue root. In those cases, leaking that information via dmesg and
> > perf isn't going to work, either.
> >
> > With lower security settings, by all means...
>
> The 'no' was categorical and unconditional though, so is the right
> answer perhaps something more along the lines of:
>
> 'Yes, the random offset can be reported in an oops, as long as
> high security setups can turn off the reporting of the offset,
> in their idealistic attempt to protect the system against root.'
>
> ?
'reporting of the offset' should probably be 'reporting kernel data' -
there's many possible ways an oops (and its associated raw stack dump)
can leak the offset, I'm not sure this can ever be made 'safe' against
a rougue root.
Not giving kernel originated debug information at all would. (At the
cost of reducing the utility of having that root user around, of
course.)
Thanks,
Ingo
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