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From: Andrew Morton <>
To: Dan Rosenberg <>
Subject: Re: [PATCH v2] kptr_restrict for hiding kernel pointers from unprivileged users
Date: Fri, 17 Dec 2010 17:22:31 -0800	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <1292634759.9764.26.camel@Dan>

On Fri, 17 Dec 2010 20:12:39 -0500
Dan Rosenberg <> 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.  

  reply	other threads:[~2010-12-18  1:22 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-12-11  0:05 [PATCH v2] kptr_restrict for hiding kernel pointers from unprivileged users Dan Rosenberg
2010-12-11  0:11 ` Kees Cook
2010-12-18  0:44 ` Andrew Morton
2010-12-18  1:12   ` Dan Rosenberg
2010-12-18  1:22     ` Andrew Morton [this message]
2010-12-18  5:22       ` Dan Rosenberg
2010-12-18  0:53 ` Andrew Morton

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