kernel-hardening - Re: [PATCH v2 1/5] fs: Add support for an O_MAYEXEC flag on sys

Follow @Openwall on Twitter for new release announcements and other news

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87r24tcljg.fsf@oldenburg2.str.redhat.com>
Date: Fri, 06 Sep 2019 20:44:03 +0200
From: Florian Weimer <fweimer@...hat.com>
To: Jeff Layton <jlayton@...nel.org>
Cc: Mickaël Salaün <mickael.salaun@....gouv.fr>,
  Mickaël Salaün
 <mic@...ikod.net>,  linux-kernel@...r.kernel.org,  Aleksa Sarai
 <cyphar@...har.com>,  Alexei Starovoitov <ast@...nel.org>,  Al Viro
 <viro@...iv.linux.org.uk>,  Andy Lutomirski <luto@...nel.org>,  Christian
 Heimes <christian@...hon.org>,  Daniel Borkmann <daniel@...earbox.net>,
  Eric Chiang <ericchiang@...gle.com>,  James Morris <jmorris@...ei.org>,
  Jan Kara <jack@...e.cz>,  Jann Horn <jannh@...gle.com>,  Jonathan Corbet
 <corbet@....net>,  Kees Cook <keescook@...omium.org>,  Matthew Garrett
 <mjg59@...gle.com>,  Matthew Wilcox <willy@...radead.org>,  Michael
 Kerrisk <mtk.manpages@...il.com>,  Mimi Zohar <zohar@...ux.ibm.com>,
  Philippe Trébuchet <philippe.trebuchet@....gouv.fr>,
  Scott Shell
 <scottsh@...rosoft.com>,  Sean Christopherson
 <sean.j.christopherson@...el.com>,  Shuah Khan <shuah@...nel.org>,  Song
 Liu <songliubraving@...com>,  Steve Dower <steve.dower@...hon.org>,  Steve
 Grubb <sgrubb@...hat.com>,  Thibaut Sautereau
 <thibaut.sautereau@....gouv.fr>,  Vincent Strubel
 <vincent.strubel@....gouv.fr>,  Yves-Alexis Perez
 <yves-alexis.perez@....gouv.fr>,  kernel-hardening@...ts.openwall.com,
  linux-api@...r.kernel.org,  linux-security-module@...r.kernel.org,
  linux-fsdevel@...r.kernel.org
Subject: Re: [PATCH v2 1/5] fs: Add support for an O_MAYEXEC flag on sys_open()

* Jeff Layton:

> Even better would be to declare the new flag in some openat2-only flag
> space, so there's no confusion about it being supported by legacy open
> calls.

Isn't that desirable anyway because otherwise fcntl with F_GETFL will
give really confusing results?

> If glibc wants to implement an open -> openat2 wrapper in userland
> later, it can set that flag in the wrapper implicitly to emulate the old
> behavior.

I see us rather doing the opposite, i.e. implement openat2 with
non-exotic flags using openat.  But we've bitten by this in the past, so
maybe that's not such a great idea.  It's tempting to make the same
mistake again for every new system call.

Thanks,
Florian

Confused about mailing lists and their use? Read about mailing lists on Wikipedia and check out these guidelines on proper formatting of your messages.