linux-kernel - [RFC PATCH v1 0/3] Expose Landlock domain IDs via pidfd

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Message-ID: <20250131163447.1140564-1-mic@digikod.net>
Date: Fri, 31 Jan 2025 17:34:44 +0100
From: Mickaël Salaün <mic@...ikod.net>
To: Christian Brauner <brauner@...nel.org>,
	Günther Noack <gnoack@...gle.com>
Cc: Mickaël Salaün <mic@...ikod.net>,
	Charles Zaffery <czaffery@...lox.com>,
	Daniel Burgener <dburgener@...ux.microsoft.com>,
	Francis Laniel <flaniel@...ux.microsoft.com>,
	James Morris <jmorris@...ei.org>,
	Jann Horn <jannh@...gle.com>,
	Jeff Xu <jeffxu@...gle.com>,
	Kees Cook <kees@...nel.org>,
	Luca Boccassi <luca.boccassi@...il.com>,
	Mikhail Ivanov <ivanov.mikhail1@...wei-partners.com>,
	Praveen K Paladugu <prapal@...ux.microsoft.com>,
	Robert Salvet <robert.salvet@...lox.com>,
	Shervin Oloumi <enlightened@...gle.com>,
	Tyler Hicks <code@...icks.com>,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org
Subject: [RFC PATCH v1 0/3] Expose Landlock domain IDs via pidfd

Hi,

Landlock enables users to create unprivileged nested security sandboxes
(i.e. domains).  Each of these domains get a unique ID, which is used to
identify and compare different domains.  With the audit support, these
IDs will be used in logs, but users also need a way to map these IDs to
processes and directly read domain IDs of arbitrary tasks.

pidfd is a reference to a task that enables users to interact with it
and read some of its properties with the PIDFD_GET_INFO IOCTL.  This
patch series extend this interface with two new properties:
PIDFD_INFO_LANDLOCK_LAST_DOMAIN and PIDFD_INFO_LANDLOCK_FIRST_DOMAIN.

Being able to read tasks' domain IDs is useful for telemetry, debugging, and
tests.  It enables users:
- to know if a task is well sandboxed;
- to know which tasks are part of the same sandbox;
- to map Landlock audit logs to running processes.

Furthermore, thanks to recvmsg(2)'s SCM_PIDFD, it is also possible to reliably
identify a peer's sandbox.

This patch series is based on the audit support patch series v5:
https://lore.kernel.org/all/20250108154338.1129069-1-mic@digikod.net/

I'll talk about this feature at FOSDEM:
https://fosdem.org/2025/schedule/event/fosdem-2025-6071-sandbox-ids-with-landlock/

Regards,

Mickaël Salaün (3):
  landlock: Add landlock_read_domain_id()
  pidfd: Extend PIDFD_GET_INFO with PIDFD_INFO_LANDLOCK_*_DOMAIN
  samples/landlock: Print domain ID

 fs/pidfs.c                   | 24 +++++++++++-
 include/linux/landlock.h     | 26 +++++++++++++
 include/uapi/linux/pidfd.h   |  4 ++
 samples/landlock/sandboxer.c | 29 +++++++++++++-
 security/landlock/Makefile   | 12 ++++--
 security/landlock/domain.c   |  2 -
 security/landlock/domain.h   |  8 ++--
 security/landlock/ruleset.c  |  2 +
 security/landlock/syscalls.c | 75 ++++++++++++++++++++++++++++++++++++
 9 files changed, 169 insertions(+), 13 deletions(-)
 create mode 100644 include/linux/landlock.h


base-commit: a4b76d5e6800121372b88c85628a7867a5fdc707
-- 
2.48.1