From: Chris Mason <clm@fb.com>
To: Colin Walters <walters@verbum.org>
Cc: Dave Chinner <david@fromorbit.com>, Jann Horn <jannh@google.com>,
"Omar Sandoval" <osandov@osandov.com>,
Aleksa Sarai <cyphar@cyphar.com>, Jens Axboe <axboe@kernel.dk>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
"linux-btrfs@vger.kernel.org" <linux-btrfs@vger.kernel.org>,
Linux API <linux-api@vger.kernel.org>,
Kernel Team <Kernel-team@fb.com>,
"Andy Lutomirski" <luto@kernel.org>
Subject: Re: [RFC PATCH 2/3] add RWF_ENCODED for writing compressed data
Date: Wed, 25 Sep 2019 14:56:15 +0000 [thread overview]
Message-ID: <FF3F534F-B40D-4D7D-956B-F1B63C4751CC@fb.com> (raw)
In-Reply-To: <60c48ac5-b215-44e1-a628-6145d84a4ce3@www.fastmail.com>
On 25 Sep 2019, at 8:07, Colin Walters wrote:
> On Wed, Sep 25, 2019, at 3:11 AM, Dave Chinner wrote:
>>
>> We're talking about user data read/write access here, not some
>> special security capability. Access to the data has already been
>> permission checked, so why should the format that the data is
>> supplied to the kernel in suddenly require new privilege checks?
>
> What happens with BTRFS today if userspace provides invalid compressed
> data via this interface? Does that show up as filesystem corruption
> later? If the data is verified at write time, wouldn't that be losing
> most of the speed advantages of providing pre-compressed data?
The data is verified while being decompressed, but that's a fairly large
fuzzing surface (all of zstd, zlib, and lzo). A lot of people will
correctly argue that we already have that fuzzing surface today, but I'd
rather not make a really easy way to stuff arbitrary bytes through the
kernel decompression code until all the projects involved sign off.
-chris
next prev parent reply other threads:[~2019-09-25 14:58 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-19 6:53 [RFC PATCH 0/3] fs: interface for directly writing encoded (e.g., compressed) data Omar Sandoval
2019-09-19 6:53 ` [RFC PATCH 1/3] fs: pass READ/WRITE to kiocb_set_rw_flags() Omar Sandoval
2019-09-20 14:38 ` Jan Kara
2019-09-19 6:53 ` [PATCH] readv.2: Document new RWF_ENCODED flag to pwritev2() Omar Sandoval
2019-09-19 6:53 ` [RFC PATCH 2/3] fs: add RWF_ENCODED for writing compressed data Omar Sandoval
2019-09-19 15:44 ` Jann Horn
2019-09-20 16:25 ` Jens Axboe
2019-09-24 17:15 ` Omar Sandoval
2019-09-24 19:35 ` Omar Sandoval
2019-09-24 20:01 ` Jann Horn
2019-09-24 20:22 ` Christian Brauner
2019-09-24 20:50 ` Matthew Wilcox
2019-09-24 20:38 ` Omar Sandoval
2019-09-25 7:11 ` Dave Chinner
2019-09-25 12:07 ` Colin Walters
2019-09-25 14:56 ` Chris Mason [this message]
2019-09-26 12:17 ` [RFC PATCH 2/3] " Colin Walters
2019-09-26 17:46 ` Omar Sandoval
2019-09-25 15:08 ` [RFC PATCH 2/3] fs: " Theodore Y. Ts'o
2019-09-25 22:52 ` Dave Chinner
2019-09-26 0:36 ` Omar Sandoval
2019-09-19 6:53 ` [RFC PATCH 3/3] btrfs: implement encoded (compressed) writes Omar Sandoval
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