From: "H. Peter Anvin" <hpa@zytor.com>
To: Kees Cook <keescook@chromium.org>
Cc: mtk.manpages@gmail.com, Rusty Russell <rusty@rustcorp.com.au>,
linux-kernel@vger.kernel.org,
Andrew Morton <akpm@linux-foundation.org>,
Mimi Zohar <zohar@linux.vnet.ibm.com>,
Serge Hallyn <serge.hallyn@canonical.com>,
Arnd Bergmann <arnd@arndb.de>,
James Morris <james.l.morris@oracle.com>,
Al Viro <viro@zeniv.linux.org.uk>, Eric Paris <eparis@redhat.com>,
Jiri Kosina <jkosina@suse.cz>,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH 1/4] module: add syscall to load module from fd
Date: Thu, 18 Oct 2012 08:30:27 -0700 [thread overview]
Message-ID: <50802093.2000301@zytor.com> (raw)
In-Reply-To: <CAGXu5jJSz8aQiyNk9q3B05SRVm_YE=krg+Y91BU7550AOSRTSw@mail.gmail.com>
On 10/18/2012 08:28 AM, Kees Cook wrote:
>
> The goal for finit_module is to make sure we're getting what's on the
> filesystem, not an arbitrary blob, so we can reason about it for
> security policy.
>
Yes, I get that... although I'm starting to think that that might
actually be a really bad idea.
>> was confused about the functioning of the *current* init_module() system
>> call.
>>
>> Given that, I have to say I now seriously question the value of
>> finit_module(). The kernel can trivially discover if the pointed-to memory
>> area is a MAP_SHARED mmap() of a file descriptor and if so which file
>> descriptor... why can't we handle this behind the scenes?
>
> This makes me very nervous. I worry that it adds needless complexity
> (it'd be many more checks besides "is it MAP_SHARED?", like "does the
> memory region show the whole file?" "is the offset zero?" etc). Also
> are we sure the memory area would be truly be unmodifiable in the case
> where the filesystem is read-only?
You may need to check for PROT_READONLY as well.
-hpa
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
next prev parent reply other threads:[~2012-10-18 15:37 UTC|newest]
Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-09-20 22:14 [PATCH 1/4] module: add syscall to load module from fd Kees Cook
2012-09-20 22:14 ` [PATCH 2/4] security: introduce kernel_module_from_file hook Kees Cook
2012-09-21 12:42 ` Mimi Zohar
2012-09-20 22:14 ` [PATCH 3/4] ARM: add finit_module syscall to ARM Kees Cook
2012-09-21 13:15 ` Arnd Bergmann
2012-09-21 14:59 ` Russell King
2012-09-21 15:43 ` Kees Cook
2012-09-20 22:15 ` [PATCH 4/4] add finit_module syscall to asm-generic Kees Cook
2012-09-21 2:22 ` [PATCH 1/4] module: add syscall to load module from fd James Morris
2012-09-21 3:07 ` Kees Cook
2012-09-21 3:09 ` Mimi Zohar
2012-09-21 17:56 ` John Johansen
2012-10-03 22:40 ` Kees Cook
2012-10-04 5:39 ` Rusty Russell
2012-10-04 12:50 ` Mimi Zohar
2012-10-05 3:50 ` Rusty Russell
2012-10-05 7:12 ` Kees Cook
2012-10-04 20:28 ` Kees Cook
2012-10-09 21:54 ` Michael Kerrisk
2012-10-09 21:58 ` H. Peter Anvin
2012-10-09 22:03 ` Michael Kerrisk (man-pages)
2012-10-09 22:09 ` H. Peter Anvin
[not found] ` <CAKgNAkjfkbYOQocuGRAKU=0P2CQCvmedhRMJZPnkUMnnxSOsqg@mail.gmail.com>
2012-10-10 5:54 ` Michael Kerrisk (man-pages)
2012-10-11 22:16 ` Rusty Russell
2012-10-12 5:16 ` Michael Kerrisk (man-pages)
2012-10-18 3:12 ` Rusty Russell
2012-10-18 5:39 ` Lucas De Marchi
2012-10-18 12:59 ` Michael Kerrisk (man-pages)
2012-10-22 7:39 ` Rusty Russell
2012-10-23 2:37 ` Lucas De Marchi
2012-10-23 3:40 ` Kees Cook
2012-10-23 4:08 ` Lucas De Marchi
2012-10-23 15:42 ` Kees Cook
2012-10-23 15:45 ` H. Peter Anvin
2012-10-23 16:25 ` Lucas De Marchi
2012-10-24 3:06 ` Rusty Russell
2012-10-23 7:38 ` Michael Kerrisk (man-pages)
2012-10-30 21:57 ` Kees Cook
2012-11-01 1:03 ` Rusty Russell
2012-12-21 0:01 ` Michael Kerrisk
2013-01-03 0:12 ` Rusty Russell
2013-01-06 18:59 ` Michael Kerrisk (man-pages)
2013-01-06 20:24 ` Kees Cook
2013-01-07 1:41 ` Michael Kerrisk (man-pages)
2013-01-09 17:29 ` Lucas De Marchi
2013-01-10 0:55 ` Michael Kerrisk (man-pages)
2012-10-18 4:24 ` H. Peter Anvin
2012-10-18 8:05 ` Michael Kerrisk (man-pages)
2012-10-18 14:26 ` H. Peter Anvin
2012-10-18 15:28 ` Kees Cook
2012-10-18 15:30 ` H. Peter Anvin [this message]
2012-10-19 2:23 ` Rusty Russell
2012-10-19 2:54 ` H. Peter Anvin
2012-10-19 10:46 ` Alon Ziv
2012-10-20 4:05 ` Rusty Russell
-- strict thread matches above, loose matches on Subject: below --
2012-10-04 20:22 [PATCH v5] " Kees Cook
2012-10-04 20:22 ` [PATCH 1/4] " Kees Cook
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