From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <owner-linux-mm@kvack.org>
Received: from mail-oi0-f69.google.com (mail-oi0-f69.google.com [209.85.218.69])
	by kanga.kvack.org (Postfix) with ESMTP id EA36B6B025F
	for <linux-mm@kvack.org>; Mon,  7 Aug 2017 15:46:42 -0400 (EDT)
Received: by mail-oi0-f69.google.com with SMTP id b130so1078697oii.4
        for <linux-mm@kvack.org>; Mon, 07 Aug 2017 12:46:42 -0700 (PDT)
Received: from mail-io0-x22b.google.com (mail-io0-x22b.google.com. [2607:f8b0:4001:c06::22b])
        by mx.google.com with ESMTPS id h3si6036577oia.98.2017.08.07.12.46.41
        for <linux-mm@kvack.org>
        (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128);
        Mon, 07 Aug 2017 12:46:42 -0700 (PDT)
Received: by mail-io0-x22b.google.com with SMTP id o9so6362940iod.1
        for <linux-mm@kvack.org>; Mon, 07 Aug 2017 12:46:41 -0700 (PDT)
MIME-Version: 1.0
In-Reply-To: <CAN=P9pi+8ufOFQJbKFDeAqHeBzBzvxsuG-dFD=_TpmRyU0vqmQ@mail.gmail.com>
References: <CACT4Y+bLGEC=14CUJpkMhw0toSxvbyqKj49kqqW+gCLLBDFu4A@mail.gmail.com>
 <CAGXu5jJhFt8JNFRnB-oiGjNy=Auo4bGx=i=DDtCa__20acANBQ@mail.gmail.com>
 <CAN=P9pj_jbTgGoiECmu-b=s+NOL6uTkPbXDueXLhs8C6PVbLHg@mail.gmail.com>
 <CAGXu5jLRG6Xee-dJGPwmbfcVFLuTP9+5mexJyvZamQQdSaHNtA@mail.gmail.com>
 <1502131739.1803.12.camel@gmail.com> <CAGXu5jKj0M55wK=0WE_uKJpiJ031J5jPVAZR-VA7_O2qJUi=BQ@mail.gmail.com>
 <CAN=P9pj0TSbwTogLAJrm=yszq+86X0EmXNK-0Oq9f7wQCkQRjA@mail.gmail.com>
 <CAGXu5jJOOvv=zgSWnKJOae0edKG8MUV1pto1ipijPiRsOdKr+Q@mail.gmail.com>
 <CAN=P9pgcuXUk=+TvFC83UT7xT66=X2ouvEEWxzVVeM2mC=Tk=g@mail.gmail.com>
 <CAGXu5jJNW5PYacSNrGGnyAxnv4cRuhbo+P9myHP9kcV7hMzhkA@mail.gmail.com>
 <CAN=P9ph4f3S3SwSpmpApKKnQ=ce6JXLcpqHG+oJ8EpmSiur0AA@mail.gmail.com>
 <CAGXu5j+x=vFrd7Owu=CgQcF7YtFAgPxUVo6G=Jzk6fo6mOQZqg@mail.gmail.com>
 <CAN=P9pg25a80so+RFxpUkm1=JAVtOj_T6CaO3GSZc2+A-PPk6A@mail.gmail.com>
 <CAGXu5jKD0Z=BKxKLDtjKq6sLgoa36bJZmc88k4QRPOHyRQp3BQ@mail.gmail.com> <CAN=P9pi+8ufOFQJbKFDeAqHeBzBzvxsuG-dFD=_TpmRyU0vqmQ@mail.gmail.com>
From: Kees Cook <keescook@google.com>
Date: Mon, 7 Aug 2017 12:46:40 -0700
Message-ID: <CAGXu5jLR-qz9dM=OmtZvT6PiU3zePnZq0i0Hx0wnaPKhB7m6TA@mail.gmail.com>
Subject: Re: binfmt_elf: use ELF_ET_DYN_BASE only for PIE breaks asan
Content-Type: text/plain; charset="UTF-8"
Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>
To: Kostya Serebryany <kcc@google.com>
Cc: Daniel Micay <danielmicay@gmail.com>, Dmitry Vyukov <dvyukov@google.com>, Michal Hocko <mhocko@kernel.org>, Andrew Morton <akpm@linux-foundation.org>, "linux-mm@kvack.org" <linux-mm@kvack.org>, Rik van Riel <riel@redhat.com>, Reid Kleckner <rnk@google.com>, Peter Collingbourne <pcc@google.com>, Evgeniy Stepanov <eugenis@google.com>

On Mon, Aug 7, 2017 at 12:40 PM, Kostya Serebryany <kcc@google.com> wrote:
>
>
> On Mon, Aug 7, 2017 at 12:34 PM, Kees Cook <keescook@google.com> wrote:
>>
>> (To be clear, this subthread is for dealing with _future_ changes; I'm
>> already preparing the revert, which is in the other subthread.)
>>
>> On Mon, Aug 7, 2017 at 12:26 PM, Kostya Serebryany <kcc@google.com> wrote:
>> > Oh, a launcher (e.g. just using setarch) would be a huge pain to deploy.
>>
>> Would loading the executable into the mmap region work?
>
> This is beyond my knowledge. :(
> Could you explain?

PIE has a separate randomization base (before at 0x5555 5555 4000,
currently 0x1 0000 0000) from the mmap (DSO) area (0x7f00 0000
0000-ish). The primary reason to keep PIE separate from mmap is to
avoid leaking ASLR offsets between them, but if that's less of a
concern for *San, then we could just load PIE into the mmap region.

> If we can do this w/o a launcher (and w/o re-executing), we should try.

Let me think about the best way to do this...

-Kees

-- 
Kees Cook
Pixel Security

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>