From: Andy Lutomirski <luto@amacapital.net>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jeff Layton <jlayton@kernel.org>,
Aleksa Sarai <cyphar@cyphar.com>,
Al Viro <viro@zeniv.linux.org.uk>,
"J. Bruce Fields" <bfields@fieldses.org>,
Arnd Bergmann <arnd@arndb.de>,
David Howells <dhowells@redhat.com>,
Shuah Khan <shuah@kernel.org>,
Shuah Khan <skhan@linuxfoundation.org>,
Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
Christian Brauner <christian@brauner.io>,
Eric Biederman <ebiederm@xmission.com>,
Andy Lutomirski <luto@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
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Tycho Andersen <tycho@tycho.ws>,
David Drysdale <drysdale@google.com>,
Chanho Min <chanho.min@lge.com>, Oleg Nesterov <oleg@redhat.com>,
Rasmus Villemoes <linux@rasmusvillemoes.dk>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
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Subject: Re: [PATCH v12 11/12] open: openat2(2) syscall
Date: Sat, 7 Sep 2019 10:42:23 -0700 [thread overview]
Message-ID: <C81D6D29-F6BF-48E6-A15E-3ABCB2C992E5@amacapital.net> (raw)
In-Reply-To: <CAHk-=whZx97Nm-gUK0ppofj2RA2LLz2vmaDUTKSSV-+yYB9q_Q@mail.gmail.com>
> On Sep 7, 2019, at 9:58 AM, Linus Torvalds <torvalds@linux-foundation.org> wrote:
>
>> On Sat, Sep 7, 2019 at 5:40 AM Jeff Layton <jlayton@kernel.org> wrote:
>>
>> After thinking about this a bit, I wonder if we might be better served
>> with a new set of OA2_* flags instead of repurposing the O_* flags?
>
> I'd hate to have yet _another_ set of translation functions, and
> another chance of people just getting it wrong either in user space or
> the kernel.
>
> So no. Let's not make another set of flags that has no sane way to
> have type-safety to avoid more confusion.
>
> The new flags that _only_ work with openat2() might be named with a
> prefix/suffix to mark that, but I'm not sure it's a huge deal.
>
>
I agree with the philosophy, but I think it doesn’t apply in this case. Here are the flags:
O_RDONLY, O_WRONLY, O_RDWR: not even a proper bitmask. The kernel already has the FMODE_ bits to make this make sense. How about we make the openat2 permission bits consistent with the internal representation and let the O_ permission bits remain as an awful translation. The kernel already translates like this, and it already sucks.
O_CREAT, O_TMPFILE, O_NOCTTY, O_TRUNC: not modes on the fd at all. These affect the meaning of open(). Heck, for openat2, NOCTTY should be this default.
O_EXCL: hopelessly overloaded.
O_APPEND, O_DIRECT, O_SYNC, O_DSYNC, O_LARGEFILE, O_NOATIME, O_PATH, O_NONBLOCK: genuine mode bits
O_CLOEXEC: special because it affects the fd, not the struct file.
Linus, you rejected resolveat() because you wanted a *nice* API that people would use and that might even be adopted by other OSes. Let’s please not make openat2() be a giant pile of crap in the name of consistency with open(). open(), frankly, is horrible.
next prev parent reply other threads:[~2019-09-07 17:42 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-04 20:19 [PATCH v12 00/12] namei: openat2(2) path resolution restrictions Aleksa Sarai
2019-09-04 20:19 ` [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Aleksa Sarai
2019-09-04 20:48 ` Linus Torvalds
2019-09-04 21:00 ` Randy Dunlap
2019-09-05 7:32 ` Peter Zijlstra
2019-09-05 9:26 ` Aleksa Sarai
2019-09-05 9:43 ` Peter Zijlstra
2019-09-05 10:57 ` Peter Zijlstra
2019-09-11 10:37 ` Aleksa Sarai
2019-09-05 13:35 ` Aleksa Sarai
2019-09-05 17:01 ` Aleksa Sarai
2019-09-05 8:43 ` Rasmus Villemoes
2019-09-05 9:50 ` Aleksa Sarai
2019-09-05 10:45 ` Christian Brauner
2019-09-05 9:09 ` Andreas Schwab
2019-09-05 10:13 ` [PATCH v12 01/12] lib: introduce copy_struct_{to, from}_user helpers Gabriel Paubert
2019-09-05 11:05 ` [PATCH v12 01/12] lib: introduce copy_struct_{to,from}_user helpers Christian Brauner
2019-09-05 11:17 ` Rasmus Villemoes
2019-09-05 11:29 ` Christian Brauner
2019-09-05 13:40 ` Aleksa Sarai
2019-09-05 11:09 ` Christian Brauner
2019-09-05 11:27 ` Aleksa Sarai
2019-09-05 11:40 ` Christian Brauner
2019-09-05 18:07 ` Al Viro
2019-09-05 18:23 ` Christian Brauner
2019-09-05 18:28 ` Al Viro
2019-09-05 18:35 ` Christian Brauner
2019-09-05 19:56 ` Aleksa Sarai
2019-09-05 22:31 ` Al Viro
2019-09-06 7:00 ` Christian Brauner
2019-09-05 23:00 ` Aleksa Sarai
2019-09-05 23:49 ` Al Viro
2019-09-06 0:09 ` Aleksa Sarai
2019-09-06 0:14 ` Al Viro
2019-09-04 20:19 ` [PATCH v12 02/12] clone3: switch to copy_struct_from_user() Aleksa Sarai
2019-09-04 20:19 ` [PATCH v12 03/12] sched_setattr: switch to copy_struct_{to,from}_user() Aleksa Sarai
2019-09-04 20:19 ` [PATCH v12 04/12] perf_event_open: switch to copy_struct_from_user() Aleksa Sarai
2019-09-04 20:19 ` [PATCH v12 05/12] namei: obey trailing magic-link DAC permissions Aleksa Sarai
2019-09-17 21:30 ` Jann Horn
2019-09-18 13:51 ` Aleksa Sarai
2019-09-18 15:46 ` Aleksa Sarai
2019-09-04 20:19 ` [PATCH v12 06/12] procfs: switch magic-link modes to be more sane Aleksa Sarai
2019-09-04 20:19 ` [PATCH v12 07/12] open: O_EMPTYPATH: procfs-less file descriptor re-opening Aleksa Sarai
2019-09-04 20:19 ` [PATCH v12 08/12] namei: O_BENEATH-style path resolution flags Aleksa Sarai
2019-09-04 20:19 ` [PATCH v12 09/12] namei: LOOKUP_IN_ROOT: chroot-like path resolution Aleksa Sarai
2019-09-04 20:19 ` [PATCH v12 10/12] namei: aggressively check for nd->root escape on ".." resolution Aleksa Sarai
2019-09-04 21:09 ` Linus Torvalds
2019-09-04 21:35 ` Linus Torvalds
2019-09-04 21:36 ` Linus Torvalds
2019-09-04 21:48 ` Aleksa Sarai
2019-09-04 22:16 ` Linus Torvalds
2019-09-04 22:31 ` David Howells
2019-09-04 22:38 ` Linus Torvalds
2019-09-04 23:29 ` Al Viro
2019-09-04 23:44 ` Linus Torvalds
2019-09-04 20:19 ` [PATCH v12 11/12] open: openat2(2) syscall Aleksa Sarai
2019-09-04 21:00 ` Randy Dunlap
2019-09-07 12:40 ` Jeff Layton
2019-09-07 16:58 ` Linus Torvalds
2019-09-07 17:42 ` Andy Lutomirski [this message]
2019-09-07 17:45 ` Linus Torvalds
2019-09-07 18:15 ` Andy Lutomirski
2019-09-10 6:35 ` Ingo Molnar
2019-09-08 16:24 ` Aleksa Sarai
2019-09-04 20:19 ` [PATCH v12 12/12] selftests: add openat2(2) selftests Aleksa Sarai
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