linux-kernel - Re: new ELF marking

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Message-ID: <CAMe9rOqH1=wOi_8AyZFURVpN999Ty1WFoTQwcOwHiBJWF_WeMA@mail.gmail.com>
Date:   Wed, 9 Aug 2017 10:16:57 -0700
From:   "H.J. Lu" <hjl.tools@...il.com>
To:     Kees Cook <keescook@...gle.com>
Cc:     LKML <linux-kernel@...r.kernel.org>,
        Binutils <binutils@...rceware.org>
Subject: Re: new ELF marking

On Wed, Aug 9, 2017 at 10:07 AM, Kees Cook via binutils
<binutils@...rceware.org> wrote:
> Hi,
>
> I'd like to be able to mark an ELF binary in such a way that Linux's
> binfmt_elf.c will collapse a PIE text area into the mmap region
> (currently they are separately randomized in memory). This is desired
> by AddressSanitizer to avoid having an ASan-built binary have its text
> area moving into an unexpected location[1] (ASLR is still desired, but
> doesn't need to have a PIE/mmap split).
>
> I see a few ways:
>
> - Add parsing for NOTE program headers and add a new NOTE type
> (NT_GNU_EXEC_FLAGS), though notes tend to be strings...
>
> - Add a new Program Header (GNU_EXEC_FLAGS), which is similar to how
> GNU_STACK and GNU_RELRO were handled. This could sort of be like NOTE
> except just lots of bit flags.
>
> - Use a filesystem xattr. This is fragile, in the case of copying
> binaries between systems or filesystems.
>
> Thoughts?
>
>

Why don't you use  NT_GNU_PROPERTY_TYPE_0?

-- 
H.J.