linux-stable/security/landlock/Kconfig
Mickaël Salaün cb2c7d1a17 landlock: Support filesystem access-control
Using Landlock objects and ruleset, it is possible to tag inodes
according to a process's domain.  To enable an unprivileged process to
express a file hierarchy, it first needs to open a directory (or a file)
and pass this file descriptor to the kernel through
landlock_add_rule(2).  When checking if a file access request is
allowed, we walk from the requested dentry to the real root, following
the different mount layers.  The access to each "tagged" inodes are
collected according to their rule layer level, and ANDed to create
access to the requested file hierarchy.  This makes possible to identify
a lot of files without tagging every inodes nor modifying the
filesystem, while still following the view and understanding the user
has from the filesystem.

Add a new ARCH_EPHEMERAL_INODES for UML because it currently does not
keep the same struct inodes for the same inodes whereas these inodes are
in use.

This commit adds a minimal set of supported filesystem access-control
which doesn't enable to restrict all file-related actions.  This is the
result of multiple discussions to minimize the code of Landlock to ease
review.  Thanks to the Landlock design, extending this access-control
without breaking user space will not be a problem.  Moreover, seccomp
filters can be used to restrict the use of syscall families which may
not be currently handled by Landlock.

Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com>
Cc: James Morris <jmorris@namei.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Serge E. Hallyn <serge@hallyn.com>
Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com>
Link: https://lore.kernel.org/r/20210422154123.13086-8-mic@digikod.net
Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 12:22:11 -07:00

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# SPDX-License-Identifier: GPL-2.0-only
config SECURITY_LANDLOCK
bool "Landlock support"
depends on SECURITY && !ARCH_EPHEMERAL_INODES
select SECURITY_PATH
help
Landlock is a sandboxing mechanism that enables processes to restrict
themselves (and their future children) by gradually enforcing
tailored access control policies. A Landlock security policy is a
set of access rights (e.g. open a file in read-only, make a
directory, etc.) tied to a file hierarchy. Such policy can be
configured and enforced by any processes for themselves using the
dedicated system calls: landlock_create_ruleset(),
landlock_add_rule(), and landlock_restrict_self().
See Documentation/userspace-api/landlock.rst for further information.
If you are unsure how to answer this question, answer N. Otherwise,
you should also prepend "landlock," to the content of CONFIG_LSM to
enable Landlock at boot time.