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    SubjectRe: [GIT PULL] x86/kaslr for v3.14

    * Ingo Molnar <mingo@kernel.org> wrote:

    >
    > * H. Peter Anvin <hpa@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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