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SubjectRe: [PATCH v2] kptr_restrict for hiding kernel pointers from unprivileged users
On Fri, 17 Dec 2010 20:12:39 -0500
Dan Rosenberg <drosenberg@vsecurity.com> wrote:

> >
> > So what's next? We need to convert 1,000,000 %p callsites to use %pK?
> > That'll be fun. Please consider adding a new checkpatch rule which
> > detects %p and asks people whether they should have used %pK.
>
> The goal of this format specifier is specifically for pointers that are
> exposed to unprivileged users. I agree that hiding all kernel pointers
> would be nice, but I don't expect the angry masses to ever agree to
> that. For now, I'll isolate specific cases, especially in /proc, that
> are clear risks in terms of information leakage. I'll also be skipping
> over pointers written to the syslog, since I think hiding that
> information is dmesg_restrict's job.

Well... some administrators may wish to hide the pointer values even
for privileged callers. That's a pretty trivial add-on for the code
which you have, and means that those admins can also suppress the
pointers for IRQ-time callers. More /proc knobs :)

Then again, perhaps those admins would be OK if we simply disabled
plain old %p everywhere. In which case we're looking at a separate
patch, I suggest.



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