caml-list - the Caml user's mailing list
 help / color / mirror / Atom feed
From: Xavier Leroy <Xavier.Leroy@inria.fr>
To: "Richard W.M. Jones" <rich@annexia.org>
Cc: caml users <caml-list@inria.fr>, nickc@redhat.com
Subject: Re: [Caml-list] Any plans for supporting Intel CET in OCaml?
Date: Wed, 31 Jul 2019 14:05:26 +0200	[thread overview]
Message-ID: <CAH=h3gHMAB61PF2V0BkmZSh52tjPdom_EBN6yzmJPyuv89t1tw@mail.gmail.com> (raw)
In-Reply-To: <20190725142821.hf524xbdgqcshrei@annexia.org>

[-- Attachment #1: Type: text/plain, Size: 1771 bytes --]

On Thu, Jul 25, 2019 at 4:28 PM Richard W.M. Jones <rich@annexia.org> wrote:

> There's an effort to harden every binary in RHEL to protect against
> ROP-style attacks.  Of course this is mainly applicable when your
> language is vulnerable to buffer overflows, but sadly even our OCaml
> applications still link to some C libraries :-(
>
> I was looking into this and the indirect branch tracking (IBT) part
> seems simple enough.  For every indirect jump or call _target_ you
> must insert one of the two instructions ENDBR64 or ENDBR32 (both are
> NOP-like on older processors).  The processor sets a flag when an
> indirect jump is taken and #CP's if the indirect jump doesn't land on
> one of these instructions.
>

Sounds like it should be easy to add to the OCaml x86-64 back-end.


>
> There's also some stuff with shadow stacks which looks a lot more
> complicated and I didn't fully understand.  The whole thing is
> described in:
>
>
> https://software.intel.com/sites/default/files/managed/4d/2a/control-flow-enforcement-technology-preview.pdf
> https://lwn.net/Articles/758245/
>
>
I don't understand how these shadow stacks are supposed to interact with
exception handling, either Caml-style or C++/Java style.

Kind regards,

- Xavier Leroy


> Unfortunately (but for obvious reasons) every asm object in a program
> must be compiled with CET in order to enable the feature for the
> program as a whole.  This means that any mixed OCaml/C program can't
> benefit from CET even in the C parts, unless we also support this in
> the OCaml parts.
>
> Has anyone looked into supporting this kind of thing in the amd64
> backend?
>
> (I looked at the OCaml trunk and couldn't see any relevant commits,
> but maybe I missed something in my grepping).
>
> Rich.
>

[-- Attachment #2: Type: text/html, Size: 2815 bytes --]

  parent reply	other threads:[~2019-07-31 12:06 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-07-25 14:28 Richard W.M. Jones
2019-07-25 15:52 ` Gerd Stolpmann
2019-07-25 19:24   ` Hendrik Boom
2019-07-31 12:05 ` Xavier Leroy [this message]
2019-07-31 14:19   ` Hendrik Boom
2019-07-31 15:21     ` Xavier Leroy
2019-07-31 17:40       ` Ivan Gotovchits

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAH=h3gHMAB61PF2V0BkmZSh52tjPdom_EBN6yzmJPyuv89t1tw@mail.gmail.com' \
    --to=xavier.leroy@inria.fr \
    --cc=caml-list@inria.fr \
    --cc=nickc@redhat.com \
    --cc=rich@annexia.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).