From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Linus Torvalds <torvalds@linux-foundation.org>,
"Ken'ichi Ohmichi" <oomichi@mxs.nes.nec.co.jp>,
Masaki Tachibana <mas-tachibana@vf.jp.nec.com>,
Kazuhito Hagio <k-hagio@ab.jp.nec.com>
Cc: Kees Cook <keescook@chromium.org>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] uts: Don't randomize "struct uts_namespace".
Date: Sat, 7 Jul 2018 08:10:08 +0900 [thread overview]
Message-ID: <271dcdcd-d622-552c-338a-5eeca5e2b4a0@i-love.sakura.ne.jp> (raw)
In-Reply-To: <CA+55aFzK5z4VQEMQAOqVHXpm+o_gd_eg5Vecck07E=WmoO6BFA@mail.gmail.com>
Hello Ken'ichi,
I noticed that makedumpfile ( https://sourceforge.net/p/makedumpfile/code/ )
can no longer detect kernel version correctly because "struct uts_namespace"
(which is exposed to userspace via vmcoreinfo) is subjected to randomization
by GCC_PLUGIN_RANDSTRUCT kernel config option since 4.13.
The code was introduced by below commit.
commit bfc8fe181c822ad0d8495ceda3c7109a407192f0
Author: ken1_ohmichi <ken1_ohmichi>
Date: Fri Dec 22 07:41:14 2006 +0000
linux-2.6.19 support.
On linux-2.6.18 or former, the release information could be gotten from
the symbol "system_utsname". But on linux-2.6.19, it can be done from the
symbol "init_uts_ns". A new makedumpfile can get the release information
from the existing symbol.
Can you detect kernel version without using "struct uts_namespace" ?
On 2018/07/07 1:11, Linus Torvalds wrote:
> On Fri, Jul 6, 2018 at 3:07 AM Tetsuo Handa
> <penguin-kernel@i-love.sakura.ne.jp> wrote:
>>
>> I noticed that makedumpfile utility is failing to check kernel version, for
>> it depends on offset of "struct uts_namespace"->name being sizeof(int).
>
> For something like this, we fix makedumpfile instead. This is not a
> "user program" using system calls etc, this is something that delves
> into the kernel dump and tries to make sense of it.
>
> Where is the makedumpfile source code? What is it trying to do, and why?
>
> One option is to just say "hey, you can't make much sense of a
> randomized kernel dump anyway, so don't even try".
>
> Linus
>
next prev parent reply other threads:[~2018-07-06 23:10 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-06 10:07 [PATCH] uts: Don't randomize "struct uts_namespace" Tetsuo Handa
2018-07-06 16:11 ` Linus Torvalds
2018-07-06 23:10 ` Tetsuo Handa [this message]
2018-07-11 16:31 ` Kazuhito Hagio
2018-07-06 23:19 ` Kees Cook
2018-07-06 23:35 ` Tetsuo Handa
2018-07-07 0:55 ` Eric W. Biederman
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