From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Dave Chinner <david@fromorbit.com>
Cc: Christoph Hellwig <hch@infradead.org>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Eric Biggers <ebiggers@kernel.org>,
linux-fscrypt@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-ext4@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
Jaegeuk Kim <jaegeuk@kernel.org>,
Victor Hsieh <victorhsieh@google.com>,
Chandan Rajendra <chandan@linux.vnet.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH v2 01/12] fs-verity: add a documentation file
Date: Thu, 20 Dec 2018 17:01:58 -0500 [thread overview]
Message-ID: <20181220220158.GC2360@mit.edu> (raw)
In-Reply-To: <20181219213552.GO6311@dastard>
On Thu, Dec 20, 2018 at 08:35:52AM +1100, Dave Chinner wrote:
>
> The file has to be written before it has been protected, which means
> it may very well have user space allocated beyond EOF before the
> merkle tree needs to be written.
Sure, and every file system knows how to truncate a file. This isn't
hard.
> But whether or not fsverity is enabled on the filesystem, the fact
> is that the kernel code now has to support storing and reading data
> from beyond EOF. Every user, whether they are using fsverity or not,
> is now exposed to that code and a filesystem that no longer
> considers the user data region beyond EOF as write only.
That's simply not true. Number one, fsverity is not mandatory for all
file systems to implement. If XFS doesn't want to implement fscrypt
or fsverity, it doesn't have to. Number two, we're not *making* any
changes to the kernel code; nothing in mm/filemap.c, et. al. So
saying that we are making changes that are impacted by /everyone/ just
doesn't make any sense.
> How filesystems store and retrieve merkle tree data should be a
> filesystem internal detail. If how metadata is stored in th e
> filesystem is defined by the userspace API or the kernel library
> code that implements the verification feature, then it lacks the
> necessary abstraction to be a generic Linux filesystem feature.
> IOWs, it needs to be redesigned and reworked before we should
> consider it for merging.
I disagree with your aesthetics that the interface has to be
completely isolated from the implementation. If you don't want to
call it a generic file system feature, fine. It can just be something
that f2fs and ext4 uses.
- Ted
next prev parent reply other threads:[~2018-12-20 22:02 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-01 22:52 [PATCH v2 00/12] fs-verity: read-only file-based authenticity protection Eric Biggers
2018-11-01 22:52 ` [PATCH v2 01/12] fs-verity: add a documentation file Eric Biggers
2018-12-12 9:14 ` Christoph Hellwig
2018-12-12 20:26 ` Eric Biggers
2018-12-13 20:22 ` Christoph Hellwig
2018-12-14 4:48 ` Eric Biggers
2018-12-17 16:49 ` Christoph Hellwig
2018-12-17 18:32 ` Eric Biggers
2018-12-19 7:09 ` Christoph Hellwig
2018-12-17 20:00 ` Darrick J. Wong
2018-12-19 0:16 ` Theodore Y. Ts'o
2018-12-19 2:19 ` Dave Chinner
2018-12-19 19:30 ` Theodore Y. Ts'o
2018-12-19 21:35 ` Dave Chinner
2018-12-20 22:01 ` Theodore Y. Ts'o [this message]
2018-12-21 7:04 ` Christoph Hellwig
2018-12-21 10:06 ` Richard Weinberger
2018-12-21 15:47 ` Theodore Y. Ts'o
2018-12-21 15:53 ` Matthew Wilcox
2018-12-21 16:28 ` Theodore Y. Ts'o
2018-12-21 16:34 ` Matthew Wilcox
2018-12-21 19:13 ` Linus Torvalds
2018-12-22 4:17 ` Theodore Y. Ts'o
2018-12-22 22:47 ` Linus Torvalds
2018-12-23 4:34 ` Theodore Y. Ts'o
2018-12-23 4:10 ` Matthew Wilcox
2018-12-23 4:45 ` Theodore Y. Ts'o
2019-01-04 20:41 ` Daniel Colascione
2018-12-19 7:14 ` Christoph Hellwig
2018-12-19 7:11 ` Christoph Hellwig
[not found] ` <CAHk-=wiB8vGbje+NgNkMZupHsZ_cqg6YEBV+ZXSF4wnywFLRHQ@mail.gmail.com>
2018-12-19 7:19 ` Christoph Hellwig
2018-12-14 5:17 ` Theodore Y. Ts'o
2018-12-14 5:39 ` Eric Biggers
2018-12-17 16:52 ` Christoph Hellwig
2018-12-17 19:15 ` Eric Biggers
2018-12-21 16:11 ` Matthew Wilcox
2018-11-01 22:52 ` [PATCH v2 02/12] fs-verity: add setup code, UAPI, and Kconfig Eric Biggers
2018-11-01 22:52 ` [PATCH v2 03/12] fs-verity: add MAINTAINERS file entry Eric Biggers
2018-11-01 22:52 ` [PATCH v2 04/12] fs-verity: add data verification hooks for ->readpages() Eric Biggers
2018-11-01 22:52 ` [PATCH v2 05/12] fs-verity: implement FS_IOC_ENABLE_VERITY ioctl Eric Biggers
2018-11-01 22:52 ` [PATCH v2 06/12] fs-verity: implement FS_IOC_MEASURE_VERITY ioctl Eric Biggers
2018-11-01 22:52 ` [PATCH v2 07/12] fs-verity: add SHA-512 support Eric Biggers
2018-11-01 22:52 ` [PATCH v2 08/12] fs-verity: add CRC-32C support Eric Biggers
2018-11-01 22:52 ` [PATCH v2 09/12] fs-verity: support builtin file signatures Eric Biggers
2018-11-01 22:52 ` [PATCH v2 10/12] ext4: add basic fs-verity support Eric Biggers
2018-11-02 9:43 ` Chandan Rajendra
2018-11-06 1:25 ` Eric Biggers
2018-11-06 6:52 ` Chandan Rajendra
2018-11-05 21:05 ` Andreas Dilger
2018-11-06 1:11 ` Eric Biggers
2018-11-01 22:52 ` [PATCH v2 11/12] ext4: add fs-verity read support Eric Biggers
2018-11-01 22:52 ` [PATCH v2 12/12] f2fs: fs-verity support Eric Biggers
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