linux-kernel - Re: [PATCH] kernel: make /proc/kallsyms mode 400 to reduce ease of attacking

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Message-ID: <20101129214933.GD8442@1wt.eu>
Date:	Mon, 29 Nov 2010 22:49:33 +0100
From:	Willy Tarreau <w@....eu>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Ingo Molnar <mingo@...e.hu>,
	Sarah Sharp <sarah.a.sharp@...ux.intel.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Marcus Meissner <meissner@...e.de>,
	linux-kernel@...r.kernel.org, tj@...nel.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk
Subject: Re: [PATCH] kernel: make /proc/kallsyms mode 400 to reduce ease of attacking

On Mon, Nov 29, 2010 at 11:05:58AM -0800, H. Peter Anvin wrote:
> Can we please not use CAP_SYS_ADMIN for this?  Relying on CAP_SYS_ADMIN
> is worse than anything else -- it is a fixed policy hardcoded in the
> kernel, with no ability for the system owner to delegate the policy
> outward, e.g. by adding group read permission and/or chgrp the file.
> 
> Delegating CAP_SYS_ADMIN, of course, otherwise known as "everything", is
> worse than anything...

Agreed, that's why I still think that hiding lots of valuable information to
non-root users will get more users added to unmanaged sudoers files, which
will result in much more holes in the systems than we currently have.

Willy

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