linux-kernel - Re: [PATCH -next 0/5] landlock: add chmod and chown support

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Date:   Mon, 22 Aug 2022 21:17:11 +0200
From:   Günther Noack <gnoack3000@...il.com>
To:     Xiu Jianfeng <xiujianfeng@...wei.com>
Cc:     mic@...ikod.net, paul@...l-moore.com, jmorris@...ei.org,
        serge@...lyn.com, shuah@...nel.org, corbet@....net,
        linux-security-module@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-kselftest@...r.kernel.org,
        linux-doc@...r.kernel.org
Subject: Re: [PATCH -next 0/5] landlock: add chmod and chown support

Hi!

Very exciting to see! Thank you for sending this! :)

I'm just throwing in some comments based on the very similar truncate
patch set, in the hope that it helps. (But obviously, Mickaël Salaün
has the last word on this code.)

Slightly higher level question: Should we start to group the
functionality of multiple LSM hooks under one Landlock flag? (Will it
be harder to change the LSM hook interface in the future if we
continue to add one flag per hook? Or is this structure already
exposed to userspace by other LSMs?)

For example, some of the "missing" operations listed on the Landlock
documentation could also be grouped roughly as:

Modifying files:
 - truncate

Modifying file metadata:
 - chmod
 - chown
 - setxattr
 - utime

Observing files (check presence and file metadata):
 - access
 - stat
 - readlink, following links (can observe symlink presence)
 - chdir (can observe dir presence and 'x' attribute)

Ungrouped:
 - flock
 - ioctl
 - fcntl

Do you have opinions on this?

—Günther

On Mon, Aug 22, 2022 at 07:46:56PM +0800, Xiu Jianfeng wrote:
> hi,
>   this patchset adds chmod and chown support for landlock
>
> Xiu Jianfeng (5):
>   landlock: expand access_mask_t to u32 type
>   landlock: add chmod and chown support
>   landlock/selftests: add selftests for chmod and chown
>   landlock/samples: add chmod and chown support
>   landlock: update chmod and chown support in document
>
>  Documentation/userspace-api/landlock.rst     |   8 +-
>  include/uapi/linux/landlock.h                |   8 +-
>  samples/landlock/sandboxer.c                 |  12 +-
>  security/landlock/fs.c                       |  16 +-
>  security/landlock/limits.h                   |   2 +-
>  security/landlock/ruleset.h                  |   2 +-
>  security/landlock/syscalls.c                 |   2 +-
>  tools/testing/selftests/landlock/base_test.c |   2 +-
>  tools/testing/selftests/landlock/fs_test.c   | 234 ++++++++++++++++++-
>  9 files changed, 274 insertions(+), 12 deletions(-)
>
> --
> 2.17.1
>

--