From: James Morris <jmorris@namei.org> To: "Mickaël Salaün" <mickael.salaun@ssi.gouv.fr> Cc: "Jeff Layton" <jlayton@kernel.org>, "Florian Weimer" <fweimer@redhat.com>, "Mickaël Salaün" <mic@digikod.net>, linux-kernel@vger.kernel.org, "Aleksa Sarai" <cyphar@cyphar.com>, "Alexei Starovoitov" <ast@kernel.org>, "Al Viro" <viro@zeniv.linux.org.uk>, "Andy Lutomirski" <luto@kernel.org>, "Christian Heimes" <christian@python.org>, "Daniel Borkmann" <daniel@iogearbox.net>, "Eric Chiang" <ericchiang@google.com>, "Jan Kara" <jack@suse.cz>, "Jann Horn" <jannh@google.com>, "Jonathan Corbet" <corbet@lwn.net>, "Kees Cook" <keescook@chromium.org>, "Matthew Garrett" <mjg59@google.com>, "Matthew Wilcox" <willy@infradead.org>, "Michael Kerrisk" <mtk.manpages@gmail.com>, "Mimi Zohar" <zohar@linux.ibm.com>, "Philippe Trébuchet" <philippe.trebuchet@ssi.gouv.fr>, "Scott Shell" <scottsh@microsoft.com>, "Sean Christopherson" <sean.j.christopherson@intel.com>, "Shuah Khan" <shuah@kernel.org>, "Song Liu" <songliubraving@fb.com>, "Steve Dower" <steve.dower@python.org>, "Steve Grubb" <sgrubb@redhat.com>, "Thibaut Sautereau" <thibaut.sautereau@ssi.gouv.fr>, "Vincent Strubel" <vincent.strubel@ssi.gouv.fr>, "Yves-Alexis Perez" <yves-alexis.perez@ssi.gouv.fr>, kernel-hardening@lists.openwall.com, linux-api@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v2 1/5] fs: Add support for an O_MAYEXEC flag on sys_open() Date: Mon, 9 Sep 2019 03:12:38 -0700 (PDT) [thread overview] Message-ID: <alpine.LRH.2.21.1909090309260.27895@namei.org> (raw) In-Reply-To: <49e98ece-e85f-3006-159b-2e04ba67019e@ssi.gouv.fr> [-- Attachment #1: Type: text/plain, Size: 1211 bytes --] On Mon, 9 Sep 2019, Mickaël Salaün wrote: > > On 06/09/2019 21:03, James Morris wrote: > > On Fri, 6 Sep 2019, Jeff Layton wrote: > > > >> The fact that open and openat didn't vet unknown flags is really a bug. > >> > >> Too late to fix it now, of course, and as Aleksa points out, we've > >> worked around that in the past. Now though, we have a new openat2 > >> syscall on the horizon. There's little need to continue these sorts of > >> hacks. > >> > >> New open flags really have no place in the old syscalls, IMO. > > > > Agree here. It's unfortunate but a reality and Linus will reject any such > > changes which break existing userspace. > > Do you mean that adding new flags to open(2) is not possible? > > Does it means that unspecified behaviors are definitely part of the > Linux specification and can't be fixed? This is my understanding. > > As I said, O_MAYEXEC should be ignored if it is not supported by the > kernel, which perfectly fit with the current open(2) flags behavior, and > should also behave the same with openat2(2). The problem here is programs which are already using the value of O_MAYEXEC, which will break. Hence, openat2(2). -- James Morris <jmorris@namei.org>
WARNING: multiple messages have this Message-ID (diff)
From: James Morris <jmorris@namei.org> To: "Mickaël Salaün" <mickael.salaun@ssi.gouv.fr> Cc: "Jeff Layton" <jlayton@kernel.org>, "Florian Weimer" <fweimer@redhat.com>, "Mickaël Salaün" <mic@digikod.net>, linux-kernel@vger.kernel.org, "Aleksa Sarai" <cyphar@cyphar.com>, "Alexei Starovoitov" <ast@kernel.org>, "Al Viro" <viro@zeniv.linux.org.uk>, "Andy Lutomirski" <luto@kernel.org>, "Christian Heimes" <christian@python.org>, "Daniel Borkmann" <daniel@iogearbox.net>, "Eric Chiang" <ericchiang@google.com>, "Jan Kara" <jack@suse.cz>, "Jann Horn" <jannh@google.com>, "Jonathan Corbet" <corbet@lwn.net>, "Kees Cook" <keescook@chromium.org>, "Matthew Garrett" <mjg59@google.com>, "Matthew Wilcox" <willy@infradead.org>, "Michael Kerrisk" <mtk.manpages@gmail.com>, "Mimi Zohar" <zohar@linux.ibm.com>, "Philippe Trébuchet" <philippe.trebuchet@ssi.gouv.fr> Subject: Re: [PATCH v2 1/5] fs: Add support for an O_MAYEXEC flag on sys_open() Date: Mon, 9 Sep 2019 03:12:38 -0700 (PDT) [thread overview] Message-ID: <alpine.LRH.2.21.1909090309260.27895@namei.org> (raw) In-Reply-To: <49e98ece-e85f-3006-159b-2e04ba67019e@ssi.gouv.fr> [-- Attachment #1: Type: text/plain, Size: 1211 bytes --] On Mon, 9 Sep 2019, Mickaël Salaün wrote: > > On 06/09/2019 21:03, James Morris wrote: > > On Fri, 6 Sep 2019, Jeff Layton wrote: > > > >> The fact that open and openat didn't vet unknown flags is really a bug. > >> > >> Too late to fix it now, of course, and as Aleksa points out, we've > >> worked around that in the past. Now though, we have a new openat2 > >> syscall on the horizon. There's little need to continue these sorts of > >> hacks. > >> > >> New open flags really have no place in the old syscalls, IMO. > > > > Agree here. It's unfortunate but a reality and Linus will reject any such > > changes which break existing userspace. > > Do you mean that adding new flags to open(2) is not possible? > > Does it means that unspecified behaviors are definitely part of the > Linux specification and can't be fixed? This is my understanding. > > As I said, O_MAYEXEC should be ignored if it is not supported by the > kernel, which perfectly fit with the current open(2) flags behavior, and > should also behave the same with openat2(2). The problem here is programs which are already using the value of O_MAYEXEC, which will break. Hence, openat2(2). -- James Morris <jmorris@namei.org>
next prev parent reply other threads:[~2019-09-09 10:14 UTC|newest] Thread overview: 90+ messages / expand[flat|nested] mbox.gz Atom feed top 2019-09-06 15:24 [PATCH v2 0/5] Add support for O_MAYEXEC Mickaël Salaün 2019-09-06 15:24 ` Mickaël Salaün 2019-09-06 15:24 ` [PATCH v2 1/5] fs: Add support for an O_MAYEXEC flag on sys_open() Mickaël Salaün 2019-09-06 15:24 ` Mickaël Salaün 2019-09-06 15:56 ` Florian Weimer 2019-09-06 15:56 ` Florian Weimer 2019-09-06 16:06 ` Mickaël Salaün 2019-09-06 16:06 ` Mickaël Salaün 2019-09-06 16:48 ` Jeff Layton 2019-09-06 16:48 ` Jeff Layton 2019-09-06 17:13 ` Aleksa Sarai 2019-09-06 17:13 ` Aleksa Sarai 2019-09-06 19:43 ` Jeff Layton 2019-09-06 19:43 ` Jeff Layton 2019-09-06 20:06 ` Andy Lutomirski 2019-09-06 20:06 ` Andy Lutomirski 2019-09-06 20:51 ` Jeff Layton 2019-09-06 20:51 ` Jeff Layton 2019-09-06 21:27 ` Andy Lutomirski 2019-09-06 21:27 ` Andy Lutomirski 2019-09-06 22:12 ` Aleksa Sarai 2019-09-06 22:12 ` Aleksa Sarai 2019-09-09 9:33 ` Mickaël Salaün 2019-09-09 9:33 ` Mickaël Salaün 2019-09-06 22:05 ` Aleksa Sarai 2019-09-06 22:05 ` Aleksa Sarai 2019-09-06 22:18 ` Aleksa Sarai 2019-09-06 22:18 ` Aleksa Sarai 2019-09-06 17:14 ` Mickaël Salaün 2019-09-06 17:14 ` Mickaël Salaün 2019-09-06 18:38 ` Jeff Layton 2019-09-06 18:38 ` Jeff Layton 2019-09-06 18:41 ` Andy Lutomirski 2019-09-06 18:41 ` Andy Lutomirski 2019-09-09 9:18 ` Mickaël Salaün 2019-09-09 9:18 ` Mickaël Salaün 2019-09-09 15:49 ` Andy Lutomirski 2019-09-09 15:49 ` Andy Lutomirski 2019-09-06 18:44 ` Florian Weimer 2019-09-06 18:44 ` Florian Weimer 2019-09-06 19:03 ` James Morris 2019-09-06 19:03 ` James Morris 2019-09-09 9:25 ` Mickaël Salaün 2019-09-09 9:25 ` Mickaël Salaün 2019-09-09 10:12 ` James Morris [this message] 2019-09-09 10:12 ` James Morris 2019-09-09 10:54 ` Mickaël Salaün 2019-09-09 10:54 ` Mickaël Salaün 2019-09-09 12:28 ` Aleksa Sarai 2019-09-09 12:28 ` Aleksa Sarai 2019-09-09 12:33 ` Mickaël Salaün 2019-09-09 12:33 ` Mickaël Salaün 2019-09-09 11:54 ` Aleksa Sarai 2019-09-09 11:54 ` Aleksa Sarai 2019-09-09 12:28 ` Mickaël Salaün 2019-09-09 12:28 ` Mickaël Salaün 2019-09-06 17:07 ` Aleksa Sarai 2019-09-06 17:07 ` Aleksa Sarai 2019-09-06 17:20 ` Christian Brauner 2019-09-06 17:20 ` Christian Brauner 2019-09-06 17:24 ` Mickaël Salaün 2019-09-06 17:24 ` Mickaël Salaün 2019-09-06 17:40 ` Tycho Andersen 2019-09-06 17:40 ` Tycho Andersen 2019-09-06 18:27 ` Florian Weimer 2019-09-06 18:27 ` Florian Weimer 2019-09-06 18:46 ` Tycho Andersen 2019-09-06 18:46 ` Tycho Andersen 2019-09-06 15:24 ` [PATCH v2 2/5] fs: Add a MAY_EXECMOUNT flag to infer the noexec mount propertie Mickaël Salaün 2019-09-06 15:24 ` Mickaël Salaün 2019-09-06 15:24 ` [PATCH v2 3/5] fs: Enable to enforce noexec mounts or file exec through O_MAYEXEC Mickaël Salaün 2019-09-06 15:24 ` Mickaël Salaün 2019-09-06 15:24 ` [PATCH v2 4/5] selftest/exec: Add tests for O_MAYEXEC enforcing Mickaël Salaün 2019-09-06 15:24 ` Mickaël Salaün 2019-09-06 15:24 ` [PATCH v2 5/5] doc: Add documentation for the fs.open_mayexec_enforce sysctl Mickaël Salaün 2019-09-06 15:24 ` Mickaël Salaün 2019-09-06 18:50 ` [PATCH v2 0/5] Add support for O_MAYEXEC Steve Grubb 2019-09-06 18:50 ` Steve Grubb 2019-09-06 18:57 ` Florian Weimer 2019-09-06 18:57 ` Florian Weimer 2019-09-06 19:07 ` Steve Grubb 2019-09-06 19:07 ` Steve Grubb 2019-09-06 19:26 ` Andy Lutomirski 2019-09-06 19:26 ` Andy Lutomirski 2019-09-06 22:44 ` Aleksa Sarai 2019-09-06 22:44 ` Aleksa Sarai 2019-09-09 9:09 ` Mickaël Salaün 2019-09-09 9:09 ` Mickaël Salaün 2019-09-09 0:16 ` James Morris 2019-09-09 0:16 ` James Morris
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