linux-kernel - Re: [PATCH v2012.1] fs: symlink restrictions on sticky directories

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Message-ID: <CAGXu5jJ=D1pKCZ8=1-WGkm0witNEH9Ux01+1BJyZKC_DAX00aA@mail.gmail.com>
Date:	Thu, 5 Jan 2012 11:36:11 -0800
From:	Kees Cook <keescook@...omium.org>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	linux-kernel@...r.kernel.org,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Rik van Riel <riel@...hat.com>,
	Federica Teodori <federica.teodori@...glemail.com>,
	Lucian Adrian Grijincu <lucian.grijincu@...il.com>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Eric Paris <eparis@...hat.com>,
	Randy Dunlap <rdunlap@...otime.net>,
	Dan Rosenberg <drosenberg@...curity.com>,
	linux-doc@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	kernel-hardening@...ts.openwall.com
Subject: Re: [PATCH v2012.1] fs: symlink restrictions on sticky directories

On Thu, Jan 5, 2012 at 1:17 AM, Ingo Molnar <mingo@...e.hu> wrote:
> * Kees Cook <keescook@...omium.org> wrote:
>
>> @@ -1495,6 +1496,15 @@ static struct ctl_table fs_table[] = {
>>  #endif
>>  #endif
>>       {
>> +             .procname       = "protected_sticky_symlinks",
>> +             .data           = &protected_sticky_symlinks,
>> +             .maxlen         = sizeof(int),
>> +             .mode           = 0644,
>> +             .proc_handler   = proc_dointvec_minmax,
>> +             .extra1         = &zero,
>> +             .extra2         = &one,
>> +     },
>
> Small detail:
>
> Might make sense to change the .mode to 0600, to make it harder
> for unprivileged attack code to guess whether this protection
> (and the resulting audit warning to the administrator) is
> enabled on a system or not.

Sure, I have no problem with that. In addition to this change, what's
the best next step for this patch?

Thanks,

-Kees

-- 
Kees Cook
ChromeOS Security
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