From: Nicolas Boichat <drinkcat@chromium.org>
To: "Darrick J. Wong" <djwong@kernel.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
Ian Lance Taylor <iant@google.com>,
Luis Lozano <llozano@chromium.org>,
Greg KH <gregkh@linuxfoundation.org>,
Dave Chinner <david@fromorbit.com>,
linux-fsdevel@vger.kernel.org,
lkml <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 6/6] vfs: Disallow copy_file_range on generated file systems
Date: Fri, 12 Feb 2021 13:24:51 +0800 [thread overview]
Message-ID: <CANMq1KDBiPN3mE4vQ=DJc-YirPm_OP9wDfeacuKZHMLhhEYj+w@mail.gmail.com> (raw)
In-Reply-To: <20210212045902.GG7187@magnolia>
On Fri, Feb 12, 2021 at 12:59 PM Darrick J. Wong <djwong@kernel.org> wrote:
>
> On Thu, Feb 11, 2021 at 08:53:47PM -0800, Darrick J. Wong wrote:
> > On Fri, Feb 12, 2021 at 12:44:05PM +0800, Nicolas Boichat wrote:
> > > copy_file_range (which calls generic_copy_file_checks) uses the
> > > inode file size to adjust the copy count parameter. This breaks
> > > with special filesystems like procfs/sysfs/debugfs/tracefs, where
> > > the file size appears to be zero, but content is actually returned
> > > when a read operation is performed. Other issues would also
> > > happen on partial writes, as the function would attempt to seek
> > > in the input file.
> > >
> > > Use the newly introduced FS_GENERATED_CONTENT filesystem flag
> > > to return -EOPNOTSUPP: applications can then retry with a more
> > > usual read/write based file copy (the fallback code is usually
> > > already present to handle older kernels).
> > >
> > > Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
> > > ---
> > >
> > > fs/read_write.c | 3 +++
> > > 1 file changed, 3 insertions(+)
> > >
> > > diff --git a/fs/read_write.c b/fs/read_write.c
> > > index 0029ff2b0ca8..80322e89fb0a 100644
> > > --- a/fs/read_write.c
> > > +++ b/fs/read_write.c
> > > @@ -1485,6 +1485,9 @@ ssize_t vfs_copy_file_range(struct file *file_in, loff_t pos_in,
> > > if (flags != 0)
> > > return -EINVAL;
> > >
> > > + if (file_inode(file_in)->i_sb->s_type->fs_flags & FS_GENERATED_CONTENT)
> > > + return -EOPNOTSUPP;
> >
> > Why not declare a dummy copy_file_range_nop function that returns
> > EOPNOTSUPP and point all of these filesystems at it?
> >
> > (Or, I guess in these days where function pointers are the enemy,
> > create a #define that is a cast of 0x1, and fix do_copy_file_range to
> > return EOPNOTSUPP if it sees that?)
I was pondering abusing ERR_PTR(-EOPNOTSUPP) for this purpose ,-P
>
> Oh, I see, because that doesn't help if the source file is procfs and
> the dest file is (say) xfs, because the generic version will try to do
> splice magic and *poof*.
Yep. I mean, we could still add a check if the
file_in->f_op->copy_file_range == copy_file_range_nop in
do_copy_file_range...
But then we'd need to sprinkle .copy_file_range = copy_file_range_nop
in many many places (~700 as a lower bound[1]), since the file
operation structure is defined at the file level, not at the FS level,
and people are likely to forget...
[1]
$ git grep "struct file_operations.*=" | grep debug | wc -l
631
$ git grep "struct file_operations.*=" | grep trace | wc -l
84
>
> I guess the other nit thatI can think of at this late hour is ... what
> about the other virtual filesystems like configfs and whatnot? Should
> we have a way to flag them as "this can't be the source of a CFR
> request" as well?
>
> Or is it just trace/debug/proc/sysfs that have these "zero size but
> readable" speshul behaviors?
I did try to audit the other filesystems. The ones I spotted:
- devpts should be fine (only device nodes in there)
- I think pstore doesn't need the flag as it's RAM-backed and persistent.
But yes, I missed configfs, thanks for catching that. I think we need
to add the flag for that one (looks like the sizes are all 4K).
>
> --D
>
> >
> > --D
> >
> > > +
> > > ret = generic_copy_file_checks(file_in, pos_in, file_out, pos_out, &len,
> > > flags);
> > > if (unlikely(ret))
> > > --
> > > 2.30.0.478.g8a0d178c01-goog
> > >
next prev parent reply other threads:[~2021-02-12 5:26 UTC|newest]
Thread overview: 137+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-12 4:43 [PATCH 0/6] Add generated flag to filesystem struct to block copy_file_range Nicolas Boichat
2021-02-12 4:44 ` [PATCH 1/6] fs: Add flag to file_system_type to indicate content is generated Nicolas Boichat
2021-02-12 7:46 ` Greg KH
2021-02-12 8:20 ` Nicolas Boichat
2021-02-12 8:37 ` Greg KH
2021-02-12 15:33 ` Ian Lance Taylor
2021-02-12 15:45 ` Greg KH
2021-02-12 15:59 ` Ian Lance Taylor
2021-02-12 16:28 ` Greg KH
2021-02-12 20:22 ` Ian Lance Taylor
2021-02-12 23:03 ` Dave Chinner
2021-02-12 23:07 ` Ian Lance Taylor
2021-02-12 23:27 ` Dave Chinner
2021-02-12 23:54 ` Darrick J. Wong
2021-02-15 0:38 ` Dave Chinner
2021-02-15 1:12 ` Ian Lance Taylor
2021-02-15 1:25 ` Nicolas Boichat
2021-02-15 5:56 ` Amir Goldstein
2021-02-15 8:30 ` Greg KH
2021-02-12 8:22 ` Amir Goldstein
2021-02-12 8:39 ` Greg KH
2021-02-12 12:05 ` Luis Henriques
2021-02-12 12:18 ` Greg KH
2021-02-12 12:41 ` Luis Henriques
2021-02-12 14:11 ` Greg KH
2021-02-12 15:01 ` Luis Henriques
2021-02-15 6:12 ` Amir Goldstein
2021-02-15 10:39 ` Luis Henriques
2021-02-15 12:22 ` Luis Henriques
2021-02-15 14:23 ` Amir Goldstein
2021-02-15 14:51 ` Luis Henriques
2021-02-15 15:43 ` [PATCH v2] vfs: prevent copy_file_range to copy across devices Luis Henriques
2021-02-15 16:02 ` Trond Myklebust
2021-02-16 0:25 ` Steve French
2021-02-15 16:34 ` Amir Goldstein
2021-02-15 16:53 ` Trond Myklebust
2021-02-15 17:24 ` Amir Goldstein
2021-02-15 18:57 ` Trond Myklebust
2021-02-15 19:43 ` Amir Goldstein
2021-02-16 11:17 ` Luis Henriques
2021-02-16 11:28 ` gregkh
2021-02-16 12:01 ` Luis Henriques
2021-02-16 12:08 ` Greg KH
2021-02-16 13:51 ` Amir Goldstein
2021-02-16 16:42 ` Luis Henriques
2021-02-16 17:44 ` Amir Goldstein
2021-02-16 18:55 ` Luis Henriques
2021-02-16 19:20 ` Amir Goldstein
2021-02-16 19:27 ` Anna Schumaker
2021-02-16 19:31 ` Steve French
2021-02-16 19:40 ` Amir Goldstein
2021-02-16 21:15 ` Steve French
2021-02-17 8:08 ` Amir Goldstein
2021-02-17 17:26 ` [PATCH v3] vfs: fix copy_file_range regression in cross-fs copies Luis Henriques
2021-02-17 20:47 ` Amir Goldstein
2021-02-18 0:56 ` Nicolas Boichat
2021-02-18 5:32 ` Olga Kornievskaia
2021-02-18 6:47 ` Amir Goldstein
2021-02-18 16:28 ` Olga Kornievskaia
2021-02-18 7:43 ` Christoph Hellwig
2021-02-18 0:50 ` [PATCH v2] vfs: prevent copy_file_range to copy across devices Andreas Dilger
2021-02-18 7:34 ` gregkh
2021-02-16 18:54 ` Andreas Dilger
2021-02-17 4:45 ` Nicolas Boichat
2021-02-18 7:42 ` Christoph Hellwig
2021-02-18 9:10 ` Amir Goldstein
2021-02-18 10:29 ` Luis Henriques
2021-02-18 12:15 ` Luis Henriques
2021-02-18 12:49 ` Amir Goldstein
2021-02-18 14:36 ` [PATCH v4] vfs: fix copy_file_range regression in cross-fs copies Luis Henriques
2021-02-18 14:58 ` Amir Goldstein
2021-02-18 15:17 ` [PATCH v5] " Luis Henriques
2021-02-18 15:53 ` Amir Goldstein
2021-02-18 16:35 ` Luis Henriques
2021-02-18 17:18 ` [PATCH v6] " Luis Henriques
2021-02-19 21:18 ` Olga Kornievskaia
2021-02-19 21:52 ` Amir Goldstein
2021-02-21 19:58 ` [PATCH v7] " Luis Henriques
2021-02-22 3:00 ` Nicolas Boichat
2021-02-22 10:24 ` [PATCH v8] " Luis Henriques
2021-02-22 10:46 ` Amir Goldstein
2021-02-22 16:25 ` dai.ngo
2021-02-23 10:32 ` Luis Henriques
2021-02-23 15:28 ` Amir Goldstein
2021-02-23 15:29 ` dai.ngo
2021-02-23 16:02 ` dai.ngo
2021-02-23 16:47 ` Amir Goldstein
2021-02-23 16:57 ` dai.ngo
[not found] ` <e3eed18b-fc7e-e687-608b-7f662017329c@oracle.com>
2021-02-23 17:33 ` Amir Goldstein
2021-02-24 0:13 ` dai.ngo
2021-02-23 17:56 ` Luis Henriques
2021-02-23 17:13 ` Olga Kornievskaia
2021-02-24 1:00 ` Olga Kornievskaia
2021-02-24 10:23 ` Luis Henriques
2021-02-24 10:44 ` Nicolas Boichat
2021-04-09 5:23 ` Nicolas Boichat
2021-04-09 13:39 ` Luis Henriques
2021-04-09 13:50 ` Amir Goldstein
2021-04-23 4:40 ` Nicolas Boichat
2021-05-03 8:54 ` Luis Henriques
2021-02-24 5:25 ` [vfs] cb07c976be: ltp.copy_file_range01.fail kernel test robot
2021-02-24 14:23 ` [PATCH] copy_file_range.2: Kernel v5.12 updates Luis Henriques
2021-02-24 16:10 ` Amir Goldstein
2021-02-25 10:21 ` Luis Henriques
2021-02-26 10:13 ` Alejandro Colomar (man-pages)
2021-02-26 10:34 ` Amir Goldstein
2021-02-26 11:15 ` Alejandro Colomar (man-pages)
2021-02-26 13:59 ` Jeff Layton
2021-02-26 21:26 ` Alejandro Colomar (man-pages)
2021-02-26 22:18 ` Alejandro Colomar (man-pages)
2021-02-27 5:41 ` Amir Goldstein
2021-02-27 12:20 ` Alejandro Colomar (man-pages)
2021-02-27 13:49 ` [RFC v2] copy_file_range.2: Update cross-filesystem support for 5.12 Alejandro Colomar
2021-02-27 16:00 ` Amir Goldstein
2021-02-27 23:08 ` [PATCH] copy_file_range.2: Kernel v5.12 updates Steve French
2021-02-28 7:35 ` Amir Goldstein
2021-02-28 22:25 ` Steve French
2021-03-01 6:18 ` Amir Goldstein
2021-03-01 14:41 ` [RFC v3] copy_file_range.2: Update cross-filesystem support for 5.12 Alejandro Colomar
2021-03-01 14:58 ` Amir Goldstein
2021-03-04 9:38 ` [RFC v4] " Alejandro Colomar
2021-03-04 17:13 ` Darrick J. Wong
2021-03-04 18:24 ` Alejandro Colomar (man-pages)
2021-03-04 23:50 ` Darrick J. Wong
2021-02-18 20:41 ` [PATCH v2] vfs: prevent copy_file_range to copy across devices Steve French
2021-02-12 23:15 ` [PATCH 1/6] fs: Add flag to file_system_type to indicate content is generated Dave Chinner
2021-02-12 7:54 ` Amir Goldstein
2021-02-12 4:44 ` [PATCH 2/6] proc: Add FS_GENERATED_CONTENT to filesystem flags Nicolas Boichat
2021-02-12 4:44 ` [PATCH 3/6] sysfs: " Nicolas Boichat
2021-02-12 4:44 ` [PATCH 4/6] debugfs: " Nicolas Boichat
2021-02-12 4:44 ` [PATCH 5/6] tracefs: " Nicolas Boichat
2021-02-12 14:47 ` Steven Rostedt
2021-02-12 4:44 ` [PATCH 6/6] vfs: Disallow copy_file_range on generated file systems Nicolas Boichat
2021-02-12 4:53 ` Darrick J. Wong
2021-02-12 4:59 ` Darrick J. Wong
2021-02-12 5:24 ` Nicolas Boichat [this message]
2021-02-14 23:09 ` [PATCH 0/6] Add generated flag to filesystem struct to block copy_file_range Al Viro
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