Date: Tue, 07 Sep 2010 15:24:34 -0400 From: Jon Oberheide <jon@...rheide.org> To: oss-security@...ts.openwall.com Cc: Sebastian Krahmer <krahmer@...e.de>, security@...nel.org, spender@...ecurity.net, Andrew Morton <akpm@...ux-foundation.org> Subject: Re: Re: [Security] /proc infoleaks On Tue, 2010-09-07 at 03:51 -0700, Andrew Morton wrote: > On Tue, 7 Sep 2010 10:35:46 +0200 Sebastian Krahmer <krahmer@...e.de> wrote: > > > I have been elected to receive the bashing from all sides, > > so here we go. > > It is not about a new vulnerability or even a new discussion > > but needs to be discussed, at least that we have a clear > > statement about the status quo. > > > > Recent i-CAN-haz-MODHARDEN.c has shown once *again* that > > certain file permissions make no sense except to exploitation > > development. There is no reason to have files like > > > > /proc/kallsyms > > /proc/slabinfo > > /proc/zoneinfo > > > > and probably a lot of others world readable. The symbol > > addresses might be hard-coded for a certain targetlist > > inside the exploit so you can argue that there > > wont be any protection benefit from making it unreadable. > > However this argument aint a reason to also leak it for self-compiled > > kernels and doesnt even hold for dynamic/runtime content > > like slabinfos etc. > > It would be nice to have something like > > > > echo 1 > /proc/quiet > > > > or something like a umask for kernel-owned proc > > entries so that you have a polite default and are > > still able to enable it for certain profiling tools > > or whereever you need it. > > chmod 0440 /proc/slabinfo > > What am I missing here? You're missing the "secure by default" part. (Obviously hiding slabinfo doesn't prevent exploitation of the vuln, but not exposing it by default is a positive step.) Regards, Jon Oberheide -- Jon Oberheide <jon@...rheide.org> GnuPG Key: 1024D/F47C17FE Fingerprint: B716 DA66 8173 6EDD 28F6 F184 5842 1C89 F47C 17FE Download attachment "signature.asc" of type "application/pgp-signature" (199 bytes)
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