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References: <1dd9e03e-0f04-4722-0874-fb3b1757b7bb@digikod.net>
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From: Omar Polo <op@omarpolo.com>
To: =?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?= <mic@digikod.net>
Cc: gameoftrees@openbsd.org, Thomas Adam <thomas@xteddy.org>,
 landlock@lists.linux.dev
Subject: Re: GoT Landlock fixes
Date: Thu, 10 Feb 2022 22:52:05 +0100
In-reply-to: <1dd9e03e-0f04-4722-0874-fb3b1757b7bb@digikod.net>
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Hello,

Micka=C3=ABl Sala=C3=BCn <mic@digikod.net> writes:

> Hi,
>
> I noticed Omar Polo added support for Landlock to the Linux version of
> Game Of Trees [1]. This is great! However, the handled filesystem
> access is only LANDLOCK_ACCESS_FS_READ_FILE, and it will still be
> allowed to do multiple filesystem-related actions (e.g. write to
> files, remove files=E2=80=A6). I don't know much about Game Of Trees but,
> according to the commit message, I think you would like to revoke any
> (currently supported) filesystem access. You should then add the 12
> remaining access rights [2]. There is also a typo in the errno check,
> it should be EOPNOTSUPP (not ENOTSUP). You'll find a small patch
> attached. Let me know if I can help.
>
> In a nutshell, the ruleset's handled_access_fs is required for
> backward and forward compatibility (i.e. the kernel and user space may
> not know each other's supported restrictions), hence the need to be
> explicit about the denied-by-default access rights.

Yes, the original diff had all the actions, but when I picked that up
again before it got committed I got confused and dropped the others (I
was sure the checks not listed there were dropped by default.)  I humbly
apologies to everyone for the incredibly stupid mistake, I don't have
any excuse.

Regarding the ENOTSUP/EOPNOTSUPP mistake, I thought that on linux the
two errno were defined to the same value, but I agree on the change
obviously (this point was raised by Brian too recently.)

Thanks a lot for reviewing the diff and fixing my mistake!

> Regards,
>  Micka=C3=ABl
>
>
> [1]
> https://git.gameoftrees.org/gitweb/?p=3Dgot-portable.git;a=3Dcommit;h=3D9=
7799ccd4b67a81f97039305d4fdd66588da9962
> [2] https://docs.kernel.org/userspace-api/landlock.html#filesystem-flags
>
> [2. text/x-patch; 0001-portable-extend-support-for-Landlock-and-fix-error=
-h.patch]...