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oss-security: [oss-security] Re: [Security] /proc infoleaks

[oss-security] Re: [Security] /proc infoleaks

From: Andrew Morton <akpm_at_nospam>
Date: Tue Sep 07 2010 - 10:51:03 GMT
To: Sebastian Krahmer <krahmer@suse.de>

On Tue, 7 Sep 2010 10:35:46 +0200 Sebastian Krahmer <krahmer@suse.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?