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From: Andy Lutomirski <luto@amacapital.net>
To: Kees Cook <keescook@chromium.org>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	libc-alpha <libc-alpha@sourceware.org>,
	"musl@lists.openwall.com" <musl@lists.openwall.com>,
	gcc@gcc.gnu.org, Binutils <binutils@sourceware.org>
Subject: RFC: adding Linux vsyscall-disable and similar backwards-incompatibility flags to ELF headers?
Date: Tue, 1 Sep 2015 17:51:44 -0700	[thread overview]
Message-ID: <CALCETrUzU5UVe_2eWuMCOgHTs=5mnor5m0RO0STTi3K5FzdNvQ@mail.gmail.com> (raw)

Hi all-

Linux has a handful of weird features that are only supported for
backwards compatibility.  The big one is the x86_64 vsyscall page, but
uselib probably belongs on the list, too, and we might end up with
more at some point.

I'd like to add a way that new programs can turn these features off.
In particular, I want the vsyscall page to be completely gone from the
perspective of any new enough program.  This is straightforward if we
add a system call to ask for the vsyscall page to be disabled, but I'm
wondering if we can come up with a non-syscall way to do it.

I think that the ideal behavior would be that anything linked against
a sufficiently new libc would be detected, but I don't see a good way
to do that using existing toolchain features.

Ideas?  We could add a new phdr for this, but then we'd need to play
linker script games, and I'm not sure that could be done in a clean,
extensible way.

--Andy

             reply	other threads:[~2015-09-02  0:51 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-09-02  0:51 Andy Lutomirski [this message]
2015-09-02  1:12 ` Ian Lance Taylor
2015-09-02  2:23   ` Andy Lutomirski
2015-09-02  1:53 ` Brian Gerst
2015-09-02  2:21   ` Andy Lutomirski
2015-09-02 13:57     ` Brian Gerst
2015-09-02 14:08       ` Andy Lutomirski
2015-09-02  2:54 ` [musl] " Rich Felker
2015-09-02  3:39   ` Andy Lutomirski
2015-09-02  4:18     ` Rich Felker
2015-09-02  4:32       ` Andy Lutomirski
2015-09-02  4:55         ` Rich Felker
2015-09-02  5:03           ` Andy Lutomirski
2015-09-02  5:22             ` Rich Felker
2015-09-02 12:48         ` Austin S Hemmelgarn

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