lists  /  announce  owl-users  owl-dev  john-users  john-dev  passwdqc-users  yescrypt  popa3d-users  /  oss-security  kernel-hardening  musl  sabotage  tlsify  passwords  /  crypt-dev  xvendor  /  Bugtraq  Full-Disclosure  linux-kernel  linux-netdev  linux-ext4  linux-hardening  PHC 
Open Source and information security mailing list archives
Hash Suite: Windows password security audit tool. GUI, reports in PDF.
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date:   Wed, 4 Jan 2023 12:08:09 +0530
From:   Ojaswin Mujoo <>
To:     Eric Biggers <>
        Andrey Albershteyn <>
Subject: Re: [PATCH v2 00/11] fsverity: support for non-4K pages

Hi Eric,

I have roughly gone through the series and run the (patched) xfstests on
this patchset on a powerpc machine with 64k pagesize and 64k,4k and 1k
merkle tree size on EXT4 and everything seems to work correctly. 

Just for records, test generic/692 takes a lot of time to complete with
64k merkel tree size due to the calculations assuming it to be 4k,
however I was able to manually test that particular scenario. (I'll try
to send a patch to fix the fstest later).

Anyways, feel free to add:

Tested-by: Ojaswin Mujoo <>

Since I was not very familiar with the fsverty codebase, I'll try to
take some more time to review the code and get back with any


On Fri, Dec 23, 2022 at 12:36:27PM -0800, Eric Biggers wrote:
> [This patchset applies to mainline + some fsverity cleanups I sent out
>  recently.  You can get everything from tag "fsverity-non4k-v2" of
> ]
> Currently, filesystems (ext4, f2fs, and btrfs) only support fsverity
> when the Merkle tree block size, filesystem block size, and page size
> are all the same.  In practice that means 4K, since increasing the page
> size, e.g. to 16K, forces the Merkle tree block size and filesystem
> block size to be increased accordingly.  That can be impractical; for
> one, users want the same file signatures to work on all systems.
> Therefore, this patchset reduces the coupling between these sizes.
> First, patches 1-4 are cleanups.
> Second, patches 5-9 allow the Merkle tree block size to be less than the
> page size or filesystem block size, provided that it's not larger than
> either one.  This involves, among other things, changing the way that
> fs/verity/verify.c tracks which hash blocks have been verified.
> Finally, patches 10-11 make ext4 support fsverity when the filesystem
> block size is less than the page size.  Note, f2fs doesn't need similar
> changes because f2fs always assumes that the filesystem block size and
> page size are the same anyway.  I haven't looked into btrfs yet.
> I've tested this patchset using the "verity" group of tests in xfstests
> with the following xfstests patchset applied:
> "[PATCH v2 00/10] xfstests: update verity tests for non-4K block and page size"
> (
> Note: on the thread "[RFC PATCH 00/11] fs-verity support for XFS"
> (
> there have been many requests for other things to support, including:
>   * folios in the pagecache
>   * alternative Merkle tree caching methods
>   * direct I/O
>   * merkle_tree_block_size > page_size
>   * extremely large files, using a reclaimable bitmap
> We shouldn't try to boil the ocean, though, so to keep the scope of this
> patchset manageable I haven't changed it significantly from v1.  This
> patchset does bring us closer to many of the above, just not all the way
> there.  I'd like to follow up this patchset with a change to support
> folios, which should be straightforward.  Next, we can do a change to
> generalize the Merkle tree interface to allow XFS to use an alternative
> caching method, as that sounds like the highest priority item for XFS.
> Anyway, the changelog is:
> Changed in v2:
>    - Rebased onto the recent fsverity cleanups.
>    - Split some parts of the big "support verification" patch into
>      separate patches.
>    - Passed the data_pos to verify_data_block() instead of computing it
>      using page->index, to make it ready for folio and DIO support.
>    - Eliminated some unnecessary arithmetic in verify_data_block().
>    - Changed the log_* fields in merkle_tree_params to u8.
>    - Restored PageLocked and !PageUptodate checks for pagecache pages.
>    - Eliminated the change to fsverity_hash_buffer().
>    - Other small cleanups
> Eric Biggers (11):
>   fsverity: use unsigned long for level_start
>   fsverity: simplify Merkle tree readahead size calculation
>   fsverity: store log2(digest_size) precomputed
>   fsverity: use EFBIG for file too large to enable verity
>   fsverity: replace fsverity_hash_page() with fsverity_hash_block()
>   fsverity: support verification with tree block size < PAGE_SIZE
>   fsverity: support enabling with tree block size < PAGE_SIZE
>   ext4: simplify ext4_readpage_limit()
>   f2fs: simplify f2fs_readpage_limit()
>   fs/buffer.c: support fsverity in block_read_full_folio()
>   ext4: allow verity with fs block size < PAGE_SIZE
>  Documentation/filesystems/fsverity.rst |  76 +++---
>  fs/buffer.c                            |  67 ++++-
>  fs/ext4/readpage.c                     |   3 +-
>  fs/ext4/super.c                        |   5 -
>  fs/f2fs/data.c                         |   3 +-
>  fs/verity/enable.c                     | 260 ++++++++++----------
>  fs/verity/fsverity_private.h           |  20 +-
>  fs/verity/hash_algs.c                  |  24 +-
>  fs/verity/open.c                       |  98 ++++++--
>  fs/verity/verify.c                     | 325 +++++++++++++++++--------
>  include/linux/fsverity.h               |  14 +-
>  11 files changed, 565 insertions(+), 330 deletions(-)
> -- 
> 2.39.0

Powered by blists - more mailing lists