linux-kernel - Re: [PATCH v2] binfmt_elf: Update READ_IMPLIES

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Message-ID: <CAGXu5jJzzku0xjJAyD3T5SDeeoxVtA51wfHPGPrejjn_tNfJ4w@mail.gmail.com>
Date:   Wed, 24 Apr 2019 13:54:24 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Will Deacon <will.deacon@....com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Hector Marco-Gisbert <hecmargi@....es>,
        Marc Gonzalez <marc.w.gonzalez@...e.fr>,
        Jason Gunthorpe <jgg@...lanox.com>, X86 ML <x86@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Andy Lutomirski <luto@...capital.net>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Catalin Marinas <catalin.marinas@....com>,
        Mark Rutland <mark.rutland@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Kernel Hardening <kernel-hardening@...ts.openwall.com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] binfmt_elf: Update READ_IMPLIES_EXEC logic for modern CPUs

On Wed, Apr 24, 2019 at 1:51 PM Will Deacon <will.deacon@....com> wrote:
> Don't you need to hack fs/compat_binfmt_elf.c to pick this up, or am I
> missing some trick? Should just be something like below.
>
> Will
>
> --->8
>
> diff --git a/fs/compat_binfmt_elf.c b/fs/compat_binfmt_elf.c
> index 15f6e96b3bd9..694bc3ee77eb 100644
> --- a/fs/compat_binfmt_elf.c
> +++ b/fs/compat_binfmt_elf.c
> @@ -116,6 +116,11 @@
>  #define        arch_setup_additional_pages compat_arch_setup_additional_pages
>  #endif
>
> +#ifdef compat_elf_read_implies_exec
> +#undef elf_read_implies_exec
> +#define elf_read_implies_exec compat_elf_read_implies_exec
> +#endif
> +
>  /*
>   * Rename a few of the symbols that binfmt_elf.c will define.
>   * These are all local so the names don't really matter, but it

Argh. I thought I already saw stuff like this somewhere, but I think I
must have been looking at some other compat silliness. I'll fix this
and split up the series...

-- 
Kees Cook