From: "Theodore Y. Ts'o" <tytso@mit.edu>
To: Matthew Wilcox <willy@infradead.org>
Cc: 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 23:45:53 -0500 [thread overview]
Message-ID: <20181223044553.GG26547@mit.edu> (raw)
In-Reply-To: <20181223041007.GL10600@bombadil.infradead.org>
On Sat, Dec 22, 2018 at 08:10:07PM -0800, Matthew Wilcox wrote:
> 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.)
That design would require the fs-verity code to know the type of eacho
file, and where to find the in-band Merkle tree for each file type
that we wanted to support. And if you wanted to use fs-verity to
protect a sudoers text configuration file (for example), we'd have to
teach sudo how to ignore the userspace visible Merkle tree.
So I agree with you that it's *possible*. But it's ***ugly***. *Way*
uglier than putting the Merkle tree at the end of the file data and
then making it invisible to userspace.
Cheers,
- Ted
next prev parent reply other threads:[~2018-12-23 4:46 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
2018-12-23 4:45 ` Theodore Y. Ts'o [this message]
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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