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From: Jann Horn <jannh@google.com>
Date: Tue, 21 May 2024 21:01:02 +0200
Message-ID: <CAG48ez0rOch3wemsmrL-ocadG1YeJ6Lyhz1uLxJod22Unbb_GA@mail.gmail.com>
Subject: Re: [PATCH v6 0/3] implement OA2_CRED_INHERIT flag for openat2()
To: Stas Sergeev <stsp2@yandex.ru>
Cc: linux-kernel@vger.kernel.org, Stefan Metzmacher <metze@samba.org>, 
	Eric Biederman <ebiederm@xmission.com>, Alexander Viro <viro@zeniv.linux.org.uk>, 
	Andy Lutomirski <luto@kernel.org>, Christian Brauner <brauner@kernel.org>, Jan Kara <jack@suse.cz>, 
	Jeff Layton <jlayton@kernel.org>, Chuck Lever <chuck.lever@oracle.com>, 
	Alexander Aring <alex.aring@gmail.com>, David Laight <David.Laight@aculab.com>, 
	linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, 
	Paolo Bonzini <pbonzini@redhat.com>, =?UTF-8?Q?Christian_G=C3=B6ttsche?= <cgzones@googlemail.com>
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On Sat, Apr 27, 2024 at 1:24=E2=80=AFPM Stas Sergeev <stsp2@yandex.ru> wrot=
e:
> 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_ALLO=
W
> 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?