linux-kernel - Re: [PATCH v2] fs: introduce pipe-only dump mode suid

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Message-ID: <CAGXu5jJrYywN3Y93efpyxnu8AnhWsSpFuogb8=GUkOYgsH01rQ@mail.gmail.com>
Date:	Fri, 22 Jun 2012 08:30:41 -0700
From:	Kees Cook <keescook@...omium.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	linux-kernel@...r.kernel.org, Rob Landley <rob@...dley.net>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Alan Cox <alan@...ux.intel.com>,
	Marcel Holtmann <marcel@...tmann.org>,
	Doug Ledford <dledford@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Serge Hallyn <serge.hallyn@...onical.com>,
	Joe Korty <joe.korty@...r.com>,
	David Howells <dhowells@...hat.com>,
	James Morris <james.l.morris@...cle.com>,
	linux-doc@...r.kernel.org, linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2] fs: introduce pipe-only dump mode suid_dumpable=3

On Fri, Jun 22, 2012 at 7:21 AM, Eric W. Biederman
<ebiederm@...ssion.com> wrote:
> Kees Cook <keescook@...omium.org> writes:
>
>> This patch introduces suid_dumpable=3 to allow privilege-changed processes
>> to be dumped only to a pipe handler (and not directly to disk). The value
>> of suid_dumpable=2 is now deprecated, and attempting to set this sysctl
>> value returns -EINVAL.
>
> Your patch descriptoin is wrong.  Deprecate means something is encouraged
> not to be used not that the functionality is removed.  I think what
> you are trying to say is that the value suid_dumpable=2 is now historic.
>
> Your implementation is absolutely gross.  Reading the value from
> twice from user space??    Is an if statement that hard to code?

I will rework this and resend.

-Kees

-- 
Kees Cook
Chrome OS Security
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