From: Arnd Bergmann <arnd@kernel.org>
To: Alessio Balsini <balsini@android.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
Akilesh Kailash <akailash@google.com>,
Amir Goldstein <amir73il@gmail.com>,
Antonio SJ Musumeci <trapexit@spawn.link>,
David Anderson <dvander@google.com>,
Giuseppe Scrivano <gscrivan@redhat.com>,
Jann Horn <jannh@google.com>, Jens Axboe <axboe@kernel.dk>,
Martijn Coenen <maco@android.com>,
Palmer Dabbelt <palmer@dabbelt.com>,
Paul Lawrence <paullawrence@google.com>,
Peng Tao <bergwolf@gmail.com>,
Stefano Duo <duostefano93@gmail.com>,
Zimuzo Ezeozue <zezeozue@google.com>, wuyan <wu-yan@tcl.com>,
fuse-devel@lists.sourceforge.net,
Android Kernel Team <kernel-team@android.com>,
Linux FS-devel Mailing List <linux-fsdevel@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH RESEND V12 2/8] fuse: 32-bit user space ioctl compat for fuse device
Date: Thu, 18 Mar 2021 22:15:43 +0100 [thread overview]
Message-ID: <CAK8P3a36ToSbvW1F_0w0gCiWGCoZgFwoLHmQ7Tz2jtwV++VrWA@mail.gmail.com> (raw)
In-Reply-To: <YFN8IyFTdqhlS9Lf@google.com>
On Thu, Mar 18, 2021 at 5:13 PM Alessio Balsini <balsini@android.com> wrote:
> On Tue, Mar 16, 2021 at 07:53:06PM +0100, Arnd Bergmann wrote:
> > On Mon, Jan 25, 2021 at 4:48 PM Alessio Balsini <balsini@android.com> wrote:
> > >
>
> Thanks for spotting this possible criticality.
>
> I noticed that 32-bit users pace was unable to use the
> FUSE_DEV_IOC_CLONE ioctl on 64-bit kernels, so this change avoid this
> issue by forcing the kernel to interpret 32 and 64 bit
> FUSE_DEV_IOC_CLONE command as if they were the same.
As far as I can tell from the kernel headers, the command code should
be the same for both 32-bit and 64-bit tasks: 0x8004e500.
Can you find out what exact value you see in the user space that was
causing problems, and how it ended up with a different value than
the 64-bit version?
If there are two possible command codes, I'd suggest you just change
the driver to handle both variants explicitly, but not any other one.
> This is the simplest solution I could find as the UAPI is not changed
> as, as you mentioned, the argument doesn't require any conversion.
>
> I understand that this might limit possible future extensions of the
> FUSE_DEV_IOC_XXX ioctls if their in/out argument changed depending on
> the architecture, but only at that point we can switch to using the
> compat layer, right?
>
> What I'm worried about is the direction, do you think this would be an
> issue?
>
> I can start working on a compat layer fix meanwhile.
For a proper well-designed ioctl interface, compat support should not
need anything beyond the '.compat_ioctl = compat_ptr_ioctl'
assignment.
Arnd
next prev parent reply other threads:[~2021-03-18 21:16 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-01-25 15:30 [PATCH RESEND V12 0/8] fuse: Add support for passthrough read/write Alessio Balsini
2021-01-25 15:30 ` [PATCH RESEND V12 1/8] fs: Generic function to convert iocb to rw flags Alessio Balsini
2021-01-25 16:46 ` Alessio Balsini
2021-03-24 7:43 ` Rokudo Yan
2021-03-24 14:02 ` Alessio Balsini
2021-01-25 15:30 ` [PATCH RESEND V12 2/8] fuse: 32-bit user space ioctl compat for fuse device Alessio Balsini
[not found] ` <CAMAHBGzkfEd9-1u0iKXp65ReJQgUi_=4sMpmfkwEOaMp6Ux7pg@mail.gmail.com>
2021-01-27 13:40 ` Alessio Balsini
[not found] ` <CAMAHBGwpKW+30kNQ_Apt8A-FTmr94hBOzkT21cjEHHW+t7yUMQ@mail.gmail.com>
2021-01-28 14:15 ` Alessio Balsini
2021-02-05 9:54 ` Peng Tao
2021-03-16 18:57 ` Arnd Bergmann
2021-02-17 10:21 ` Miklos Szeredi
2021-03-01 12:26 ` Alessio Balsini
2021-03-16 18:53 ` Arnd Bergmann
2021-03-18 16:13 ` Alessio Balsini
2021-03-18 21:15 ` Arnd Bergmann [this message]
2021-03-19 15:21 ` Alessio Balsini
2021-01-25 15:30 ` [PATCH RESEND V12 3/8] fuse: Definitions and ioctl for passthrough Alessio Balsini
2021-02-17 13:41 ` Miklos Szeredi
2021-02-19 7:05 ` Peng Tao
2021-02-19 8:40 ` Miklos Szeredi
2021-03-01 17:05 ` Alessio Balsini
2021-01-25 15:30 ` [PATCH RESEND V12 4/8] fuse: Passthrough initialization and release Alessio Balsini
2021-02-17 13:52 ` Miklos Szeredi
2021-05-05 12:21 ` Amir Goldstein
2021-05-17 11:36 ` Alessio Balsini
2021-05-17 13:21 ` Amir Goldstein
2021-01-25 15:30 ` [PATCH RESEND V12 5/8] fuse: Introduce synchronous read and write for passthrough Alessio Balsini
2021-02-17 14:00 ` Miklos Szeredi
2021-01-25 15:30 ` [PATCH RESEND V12 6/8] fuse: Handle asynchronous read and write in passthrough Alessio Balsini
2021-01-25 15:30 ` [PATCH RESEND V12 7/8] fuse: Use daemon creds in passthrough mode Alessio Balsini
2021-02-05 9:23 ` Peng Tao
2021-02-05 11:21 ` Alessio Balsini
2021-01-25 15:30 ` [PATCH RESEND V12 8/8] fuse: Introduce passthrough for mmap Alessio Balsini
2021-02-17 14:05 ` Miklos Szeredi
2021-04-01 11:24 ` Alessio Balsini
2021-11-18 18:31 ` [PATCH RESEND V12 0/8] fuse: Add support for passthrough read/write Amir Goldstein
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