linux-kernel - Re: [PATCH v4 07/12] ppc64/kexec_file: add support to relocate purgatory

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <871rl4rxao.fsf@mpe.ellerman.id.au>
Date:   Wed, 22 Jul 2020 14:25:19 +1000
From:   Michael Ellerman <mpe@...erman.id.au>
To:     Hari Bathini <hbathini@...ux.ibm.com>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     kernel test robot <lkp@...el.com>, Pingfan Liu <piliu@...hat.com>,
        Kexec-ml <kexec@...ts.infradead.org>,
        Mimi Zohar <zohar@...ux.ibm.com>,
        Nayna Jain <nayna@...ux.ibm.com>,
        Petr Tesarik <ptesarik@...e.cz>,
        Mahesh J Salgaonkar <mahesh@...ux.ibm.com>,
        Sourabh Jain <sourabhjain@...ux.ibm.com>,
        lkml <linux-kernel@...r.kernel.org>,
        linuxppc-dev <linuxppc-dev@...abs.org>,
        Eric Biederman <ebiederm@...ssion.com>,
        Thiago Jung Bauermann <bauerman@...ux.ibm.com>,
        Dave Young <dyoung@...hat.com>, Vivek Goyal <vgoyal@...hat.com>
Subject: Re: [PATCH v4 07/12] ppc64/kexec_file: add support to relocate purgatory

Hari Bathini <hbathini@...ux.ibm.com> writes:
> Right now purgatory implementation is only minimal. But if purgatory
> code is to be enhanced to copy memory to the backup region and verify
> sha256 digest, relocations may have to be applied to the purgatory.
> So, add support to relocate purgatory in kexec_file_load system call
> by setting up TOC pointer and applying RELA relocations as needed.
>
> Reported-by: kernel test robot <lkp@...el.com>
> [lkp: In v1, 'struct mem_sym' was declared in parameter list]
> Signed-off-by: Hari Bathini <hbathini@...ux.ibm.com>
> ---
>
> * Michael, can you share your opinion on the below:
>     - https://lore.kernel.org/patchwork/patch/1272027/
>     - My intention in cover note.

It seems like a lot of complexity for little benefit.

AFAICS your final purgatory_64.c is only 36 lines, and all it does is a
single (open coded) memcpy().

It seems like we could write that in not many more lines of assembler
and avoid all this code.

What am I missing?

cheers