Date: Tue, 1 Sep 2015 21:53:12 -0400 From: Brian Gerst <brgerst@...il.com> To: Andy Lutomirski <luto@...capital.net> Cc: Kees Cook <keescook@...omium.org>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, libc-alpha <libc-alpha@...rceware.org>, "musl@...ts.openwall.com" <musl@...ts.openwall.com>, gcc@....gnu.org, Binutils <binutils@...rceware.org> Subject: Re: RFC: adding Linux vsyscall-disable and similar backwards-incompatibility flags to ELF headers? On Tue, Sep 1, 2015 at 8:51 PM, Andy Lutomirski <luto@...capital.net> wrote: > 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. The vsyscall page is mapped in the fixmap region, which is shared between all processes. You can't turn it off for an individual process. -- Brian Gerst
Powered by blists - more mailing lists
Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.