From: Matthew Wilcox <willy@infradead.org>
To: "Theodore Y. Ts'o" <tytso@mit.edu>,
Linus Torvalds <torvalds@linux-foundation.org>,
Christoph Hellwig <hch@infradead.org>,
Dave Chinner <david@fromorbit.com>,
"Darrick J. Wong" <darrick.wong@oracle.com>,
Eric Biggers <ebiggers@kernel.org>,
linux-fscrypt@vger.kernel.org,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-ext4@vger.kernel.org,
linux-f2fs-devel@lists.sourceforge.net,
linux-integrity@vger.kernel.org,
Linux List Kernel Mailing <linux-kernel@vger.kernel.org>,
Jaegeuk Kim <jaegeuk@kernel.org>,
Victor Hsieh <victorhsieh@google.com>,
Chandan Rajendra <chandan@linux.vnet.ibm.com>
Subject: Re: [PATCH v2 01/12] fs-verity: add a documentation file
Date: Sat, 22 Dec 2018 20:10:07 -0800 [thread overview]
Message-ID: <20181223041007.GL10600@bombadil.infradead.org> (raw)
In-Reply-To: <20181222041712.GC26547@mit.edu>
On Fri, Dec 21, 2018 at 11:17:12PM -0500, Theodore Y. Ts'o wrote:
> Userspace applications which are reading the file aren't going to be
> expecting Merkle tree. For example, one of the use cases is Android
> APK files, which are essentially ZIP files. ZIP files can be parsed
> both from the front-end (streaming), or by looking for the complete
> directory of all of the files in the ZIP file by starting at the end
> of the file and moving backwards. If the Merkle tree was visible to
> userspace programs that are opening and reading the file, it would
> confuse them mightily.
Pretty much every file format has the ability to put arbitrary blocks
of information into a file somewhere the tools which don't know about
it will skip it. For example, ZIP "includes an extra field facility
within file headers, which can be used to store extra data not defined
by existing ZIP specifications, and which allow compliant archivers that
do not recognize the fields to safely skip them. Header IDs 0–31 are
reserved for use by PKWARE. The remaining IDs can be used by third-party
vendors for proprietary usage. " (Wikipedia)
ELF, PNG, PDF and many other formats have the ability to put data
_somewhere_. It might not be at the tail of the file, but there's
somewhere to do it.
(I appreciate this isn't what Linus is asking for, but I'm pointing out
that this is by no means as intractable as you make it sound.)
next prev parent reply other threads:[~2018-12-23 4:10 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
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 [this message]
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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