Date: Tue, 7 Sep 2010 03:51:03 -0700 From: Andrew Morton <akpm@...ux-foundation.org> To: Sebastian Krahmer <krahmer@...e.de> Cc: oss-security@...ts.openwall.com, security@...nel.org, spender@...ecurity.net Subject: Re: [Security] /proc infoleaks 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?
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