linux-kernel - Re: [PATCH v6 0/3] implement OA2_CRED

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Message-ID: <CAG48ez0rOch3wemsmrL-ocadG1YeJ6Lyhz1uLxJod22Unbb_GA@mail.gmail.com>
Date: Tue, 21 May 2024 21:01:02 +0200
From: Jann Horn <jannh@...gle.com>
To: Stas Sergeev <stsp2@...dex.ru>
Cc: linux-kernel@...r.kernel.org, Stefan Metzmacher <metze@...ba.org>, 
	Eric Biederman <ebiederm@...ssion.com>, Alexander Viro <viro@...iv.linux.org.uk>, 
	Andy Lutomirski <luto@...nel.org>, Christian Brauner <brauner@...nel.org>, Jan Kara <jack@...e.cz>, 
	Jeff Layton <jlayton@...nel.org>, Chuck Lever <chuck.lever@...cle.com>, 
	Alexander Aring <alex.aring@...il.com>, David Laight <David.Laight@...lab.com>, 
	linux-fsdevel@...r.kernel.org, linux-api@...r.kernel.org, 
	Paolo Bonzini <pbonzini@...hat.com>, Christian Göttsche <cgzones@...glemail.com>
Subject: Re: [PATCH v6 0/3] implement OA2_CRED_INHERIT flag for openat2()

On Sat, Apr 27, 2024 at 1:24 PM Stas Sergeev <stsp2@...dex.ru> wrote:
> This patch-set implements the OA2_CRED_INHERIT flag for openat2() syscall.
> It is needed to perform an open operation with the creds that were in
> effect when the dir_fd was opened, if the dir was opened with O_CRED_ALLOW
> flag. This allows the process to pre-open some dirs and switch eUID
> (and other UIDs/GIDs) to the less-privileged user, while still retaining
> the possibility to open/create files within the pre-opened directory set.

As Andy Lutomirski mentioned before, Linux already has Landlock
(https://docs.kernel.org/userspace-api/landlock.html) for unprivileged
filesystem sandboxing. What benefits does OA2_CRED_INHERIT have
compared to Landlock?