linux-kernel - Re: [RFC 0/5 v4] procfs: introduce hidepid=, hidenet=, gid= mount options

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Date:	Wed, 29 Jun 2011 23:16:15 +0400
From:	Vasiliy Kulikov <segoon@...nwall.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
	Greg Kroah-Hartman <gregkh@...e.de>,
	"David S. Miller" <davem@...emloft.net>,
	Arnd Bergmann <arnd@...db.de>,
	Alexey Dobriyan <adobriyan@...il.com>,
	linux-security-module@...r.kernel.org
Subject: Re: [RFC 0/5 v4] procfs: introduce hidepid=, hidenet=, gid= mount
 options

On Wed, Jun 22, 2011 at 10:45 +0400, Vasiliy Kulikov wrote:
> > This all seems highly specific to one particular set of requirements. 
> 
> Yes, I admit this.  The problem with procfs is that it's possible to
> chmod/chown some procfs files, but not /proc/PID/*.  Even if make it
> possible to chmod/chown them (and introducing an inodes revalidation on
> execve() setuid and similar binaries) it is still racy - new processes
> would have /proc/PID/ and some files inside with perms=0555.  So, for
> more generic mechanism something like umask is needed.  The patch in
> question implements 2 border cases:
> 
> 1) relaxed.  umask=0555.
> 
> 2) restricted.  umask=0550 (with tricky gid) and files are still not
> chmod'able.
> 
> 
> More generic solution (I'm not suggesting it, but merely discussing)
> would use some user-supplied set of files to restrict access to (or,
> better, the set of allowed files because white list is almost always
> better than black list).  Maybe this one:
> 
>     mount -t proc -o "pid_allow=exe,status,comm,oom_*" proc /proc

Does this scheme make sense?  Should I rensend the patch with these
architecture?

pid_allow=, tid_allow=, attr_allow= and watch_gid= or smth like that.


Thanks,

-- 
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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