From: Gao Xiang <email@example.com>
To: "Theodore Y. Ts'o" <firstname.lastname@example.org>,
Eric Biggers <email@example.com>,
Dmitry Kasatkin <firstname.lastname@example.org>,
Michael Halcrow <email@example.com>,
Mimi Zohar <firstname.lastname@example.org>,
Victor Hsieh <email@example.com>
Subject: Re: [f2fs-dev] [RFC PATCH 02/10] fs-verity: add data verification hooks for ->readpages()
Date: Sat, 25 Aug 2018 15:55:18 +0800 [thread overview]
Message-ID: <firstname.lastname@example.org> (raw)
Please ignore the following email, Eric has replied to me. :)
I need to dig into these fs-verity patches later and best wishes to fs-verity.
On 2018/8/25 15:33, Gao Xiang wrote:
> Hi Ted,
> Thanks for your detailed reply. Sorry about my english, the words could not be logical.
> Tiny pieces in B-tree to compose a page is too far from us too, and you are right,
> fs-verity is complete for >99% cases for the existed file system, and no need to worry about currently.
> As I mentioned in reply to Eric, I am actually curious about the Google fs-verity roadmap
> for the future Android, I need to analyze if it is only limited to APKs for the read-write partitions
> and not to replace dm-verity in the near future since fs-verity has some conflicts
> to EROFS I am working on I mentioned in the email to Eric.
> I think it is more than just to handle FILE_MAPPING and bio-strict for compression use.
> On 2018/8/25 13:06, Theodore Y. Ts'o wrote:
>> But I'd suggest worrying about it when such a file system
>> comes out of the woodwork, and someone is willing to do the work to
>> integrate fserity in that file system.
> Yes, we are now handling partial page due to compression use.
> fs could submit bios in pages from different mapping(FILE_MAPPING[compress in-place and no caching
> compressed page to reduce extra memory overhead] or META_MAPPING [for caching compressed page]) and
> they could be decompressed into many full pages and (possible) a partial page (in-place or out-of-place).
> so in principle, since we have BIO_MAX_PAGES limitation, a filemap page could be Uptodate
> after two bios is ended and decompressed. and other runtime limitations could also divide a bio into two bios for encoded cases.
> Therefore, I think in that case we could not just consider FILE_MAPPING and one bio, and as you said `In
> that case, it could call fsverity after assembling the page in the page cache.' should be done in this way.
>> Well, the userspace interface for instantiating a fs-verity file is
>> that it writes the file data with the fs-verity metadata (which
>> consists of the Merkle tree with a fs-verity header at the end of the
>> file). The program (which might be a package manager such as dpkg or
>> rpm) would then call an ioctl which would cause the file system to
>> read the fs-verity header and make only the file data visible, and the
>> file system would the verify the data as it is read into the page
> Thanks for your reply again, I think fs-verity is good enough for now.
> However, I need to think over about fs-verity itself more... :(
> Gao Xiang
next prev parent reply other threads:[~2018-08-25 11:34 UTC|newest]
Thread overview: 46+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-08-24 16:16 [RFC PATCH 00/10] fs-verity: filesystem-level integrity protection Eric Biggers
2018-08-24 16:16 ` [RFC PATCH 01/10] fs-verity: add setup code, UAPI, and Kconfig Eric Biggers
2018-08-24 17:28 ` Randy Dunlap
2018-08-24 17:42 ` Colin Walters
2018-08-24 22:45 ` Theodore Y. Ts'o
2018-08-25 4:48 ` Eric Biggers
2018-09-14 13:15 ` Colin Walters
2018-09-14 16:21 ` Eric Biggers
2018-09-15 15:27 ` Theodore Y. Ts'o
2018-08-26 16:22 ` Chuck Lever
2018-08-26 17:17 ` Eric Biggers
2018-08-24 16:16 ` [RFC PATCH 02/10] fs-verity: add data verification hooks for ->readpages() Eric Biggers
2018-08-25 2:29 ` [f2fs-dev] " Gao Xiang
2018-08-25 3:45 ` Theodore Y. Ts'o
2018-08-25 4:00 ` Gao Xiang
2018-08-25 5:06 ` Theodore Y. Ts'o
2018-08-25 7:33 ` Gao Xiang
2018-08-25 7:55 ` Gao Xiang [this message]
2018-08-25 4:16 ` Eric Biggers
2018-08-25 6:31 ` Gao Xiang
2018-08-25 7:18 ` Eric Biggers
2018-08-25 7:43 ` Gao Xiang
2018-08-25 17:06 ` Theodore Y. Ts'o
2018-08-26 13:44 ` Gao Xiang
2018-09-02 2:35 ` Olof Johansson
2018-08-26 15:55 ` Chuck Lever
2018-08-26 17:04 ` Eric Biggers
2018-08-26 17:44 ` Gao Xiang
2018-08-24 16:16 ` [RFC PATCH 03/10] fs-verity: implement FS_IOC_ENABLE_VERITY ioctl Eric Biggers
2018-08-24 16:16 ` [RFC PATCH 04/10] fs-verity: implement FS_IOC_MEASURE_VERITY ioctl Eric Biggers
2018-08-24 16:16 ` [RFC PATCH 05/10] fs-verity: add SHA-512 support Eric Biggers
2018-08-24 16:16 ` [RFC PATCH 06/10] fs-verity: add CRC-32C support Eric Biggers
2018-08-24 16:16 ` [RFC PATCH 07/10] fs-verity: support builtin file signatures Eric Biggers
2018-08-24 16:16 ` [RFC PATCH 08/10] ext4: add basic fs-verity support Eric Biggers
2018-08-24 16:16 ` [RFC PATCH 09/10] ext4: add fs-verity read support Eric Biggers
2018-08-24 16:16 ` [RFC PATCH 10/10] f2fs: fs-verity support Eric Biggers
2018-08-25 5:54 ` [f2fs-dev] " Chao Yu
2018-08-26 17:35 ` Eric Biggers
2018-08-27 15:54 ` Chao Yu
2018-08-28 7:27 ` Jaegeuk Kim
2018-08-28 9:20 ` Chao Yu
2018-08-28 17:01 ` Jaegeuk Kim
2018-08-29 1:22 ` Chao Yu
2018-08-29 1:43 ` Jaegeuk Kim
2018-08-31 20:05 ` [RFC PATCH 00/10] fs-verity: filesystem-level integrity protection Jan Lübbe
2018-08-31 21:39 ` Eric Biggers
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