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linux/security/landlock/Kconfig

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landlock: Add object management A Landlock object enables to identify a kernel object (e.g. an inode). A Landlock rule is a set of access rights allowed on an object. Rules are grouped in rulesets that may be tied to a set of processes (i.e. subjects) to enforce a scoped access-control (i.e. a domain). Because Landlock's goal is to empower any process (especially unprivileged ones) to sandbox themselves, we cannot rely on a system-wide object identification such as file extended attributes. Indeed, we need innocuous, composable and modular access-controls. The main challenge with these constraints is to identify kernel objects while this identification is useful (i.e. when a security policy makes use of this object). But this identification data should be freed once no policy is using it. This ephemeral tagging should not and may not be written in the filesystem. We then need to manage the lifetime of a rule according to the lifetime of its objects. To avoid a global lock, this implementation make use of RCU and counters to safely reference objects. A following commit uses this generic object management for inodes. Cc: James Morris <jmorris@namei.org> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> Reviewed-by: Jann Horn <jannh@google.com> Acked-by: Serge Hallyn <serge@hallyn.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210422154123.13086-2-mic@digikod.net Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 15:41:11 +00:00
# SPDX-License-Identifier: GPL-2.0-only
config SECURITY_LANDLOCK
bool "Landlock support"
hostfs: Fix ephemeral inodes hostfs creates a new inode for each opened or created file, which created useless inode allocations and forbade identifying a host file with a kernel inode. Fix this uncommon filesystem behavior by tying kernel inodes to host file's inode and device IDs. Even if the host filesystem inodes may be recycled, this cannot happen while a file referencing it is opened, which is the case with hostfs. It should be noted that hostfs inode IDs may not be unique for the same hostfs superblock because multiple host's (backed) superblocks may be used. Delete inodes when dropping them to force backed host's file descriptors closing. This enables to entirely remove ARCH_EPHEMERAL_INODES, and then makes Landlock fully supported by UML. This is very useful for testing changes. These changes also factor out and simplify some helpers thanks to the new hostfs_inode_update() and the hostfs_iget() revamp: read_name(), hostfs_create(), hostfs_lookup(), hostfs_mknod(), and hostfs_fill_sb_common(). A following commit with new Landlock tests check this new hostfs inode consistency. Cc: Anton Ivanov <anton.ivanov@cambridgegreys.com> Cc: Johannes Berg <johannes@sipsolutions.net> Acked-by: Richard Weinberger <richard@nod.at> Link: https://lore.kernel.org/r/20230612191430.339153-2-mic@digikod.net Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-06-12 19:14:25 +00:00
depends on SECURITY
landlock: Support network rules with TCP bind and connect Add network rules support in the ruleset management helpers and the landlock_create_ruleset() syscall. Extend user space API to support network actions: * Add new network access rights: LANDLOCK_ACCESS_NET_BIND_TCP and LANDLOCK_ACCESS_NET_CONNECT_TCP. * Add a new network rule type: LANDLOCK_RULE_NET_PORT tied to struct landlock_net_port_attr. The allowed_access field contains the network access rights, and the port field contains the port value according to the controlled protocol. This field can take up to a 64-bit value but the maximum value depends on the related protocol (e.g. 16-bit value for TCP). Network port is in host endianness [1]. * Add a new handled_access_net field to struct landlock_ruleset_attr that contains network access rights. * Increment the Landlock ABI version to 4. Implement socket_bind() and socket_connect() LSM hooks, which enable to control TCP socket binding and connection to specific ports. Expand access_masks_t from u16 to u32 to be able to store network access rights alongside filesystem access rights for rulesets' handled access rights. Access rights are not tied to socket file descriptors but checked at bind() or connect() call time against the caller's Landlock domain. For the filesystem, a file descriptor is a direct access to a file/data. However, for network sockets, we cannot identify for which data or peer a newly created socket will give access to. Indeed, we need to wait for a connect or bind request to identify the use case for this socket. Likewise a directory file descriptor may enable to open another file (i.e. a new data item), but this opening is also restricted by the caller's domain, not the file descriptor's access rights [2]. [1] https://lore.kernel.org/r/278ab07f-7583-a4e0-3d37-1bacd091531d@digikod.net [2] https://lore.kernel.org/r/263c1eb3-602f-57fe-8450-3f138581bee7@digikod.net Signed-off-by: Konstantin Meskhidze <konstantin.meskhidze@huawei.com> Link: https://lore.kernel.org/r/20231026014751.414649-9-konstantin.meskhidze@huawei.com [mic: Extend commit message, fix typo in comments, and specify endianness in the documentation] Co-developed-by: Mickaël Salaün <mic@digikod.net> Signed-off-by: Mickaël Salaün <mic@digikod.net>
2023-10-26 01:47:47 +00:00
select SECURITY_NETWORK
landlock: Add object management A Landlock object enables to identify a kernel object (e.g. an inode). A Landlock rule is a set of access rights allowed on an object. Rules are grouped in rulesets that may be tied to a set of processes (i.e. subjects) to enforce a scoped access-control (i.e. a domain). Because Landlock's goal is to empower any process (especially unprivileged ones) to sandbox themselves, we cannot rely on a system-wide object identification such as file extended attributes. Indeed, we need innocuous, composable and modular access-controls. The main challenge with these constraints is to identify kernel objects while this identification is useful (i.e. when a security policy makes use of this object). But this identification data should be freed once no policy is using it. This ephemeral tagging should not and may not be written in the filesystem. We then need to manage the lifetime of a rule according to the lifetime of its objects. To avoid a global lock, this implementation make use of RCU and counters to safely reference objects. A following commit uses this generic object management for inodes. Cc: James Morris <jmorris@namei.org> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> Reviewed-by: Jann Horn <jannh@google.com> Acked-by: Serge Hallyn <serge@hallyn.com> Reviewed-by: Kees Cook <keescook@chromium.org> Link: https://lore.kernel.org/r/20210422154123.13086-2-mic@digikod.net Signed-off-by: James Morris <jamorris@linux.microsoft.com>
2021-04-22 15:41:11 +00:00
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.
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