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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Fri, 19 Nov 2010 11:54:26 -0800
Message-ID: <AANLkTi=OsWEdrfCOHKz+SAtqo7DmK0nNxku7Ev21f0Lh@mail.gmail.com>
Subject: Re: [PATCH] kernel: make /proc/kallsyms mode 400 to reduce ease of attacking
To: Sarah Sharp <sarah.a.sharp@linux.intel.com>
Cc: Marcus Meissner <meissner@suse.de>, linux-kernel@vger.kernel.org,
        tj@kernel.org, akpm@linux-foundation.org, hpa@zytor.com, mingo@elte.hu,
        w@1wt.eu, alan@lxorguk.ukuu.org.uk
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On Fri, Nov 19, 2010 at 11:19 AM, Sarah Sharp
<sarah.a.sharp@linux.intel.com> wrote:
>
> .config and dmesg are attached. ?The box is running klogd 1.5.5ubuntu3
> (from Jaunty). ?Yes, I know that's old. ?I read the bit in the commit
> about changing the permissions of kallsyms after boot, but if I can't
> boot that doesn't help. ?Perhaps this can be made a configuration
> option?

It's not worth a config option.

If it actually breaks user-space, I think we should just revert it.
It's kind of sad to default to the world-visible thing, but as I
mentioned in the commit, this is something where a sysadmin or distro
can trivially just fix it at boot-time too, with just a

   chmod og-r /proc/kallsyms

in your bootup scripts.

And if somebody has taken control of the machine _before_ the bootup
scripts get to run, you have bigger problems than a /proc/kallsyms
file.

So I guess I'll revert it.

Thanks for testing and bisecting.

                      Linus
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