xref: /linux-6.15/include/uapi/linux/landlock.h (revision 47ce2af8)

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
/*
 * Landlock - User space API
 *
 * Copyright © 2017-2020 Mickaël Salaün <[email protected]>
 * Copyright © 2018-2020 ANSSI
 * Copyright © 2021-2025 Microsoft Corporation
 */

#ifndef _UAPI_LINUX_LANDLOCK_H
#define _UAPI_LINUX_LANDLOCK_H

#include <linux/types.h>

/**
 * struct landlock_ruleset_attr - Ruleset definition.
 *
 * Argument of sys_landlock_create_ruleset().
 *
 * This structure defines a set of *handled access rights*, a set of actions on
 * different object types, which should be denied by default when the ruleset is
 * enacted.  Vice versa, access rights that are not specifically listed here are
 * not going to be denied by this ruleset when it is enacted.
 *
 * For historical reasons, the %LANDLOCK_ACCESS_FS_REFER right is always denied
 * by default, even when its bit is not set in @handled_access_fs.  In order to
 * add new rules with this access right, the bit must still be set explicitly
 * (cf. `Filesystem flags`_).
 *
 * The explicit listing of *handled access rights* is required for backwards
 * compatibility reasons.  In most use cases, processes that use Landlock will
 * *handle* a wide range or all access rights that they know about at build time
 * (and that they have tested with a kernel that supported them all).
 *
 * This structure can grow in future Landlock versions.
 */
struct landlock_ruleset_attr {
	/**
	 * @handled_access_fs: Bitmask of handled filesystem actions
	 * (cf. `Filesystem flags`_).
	 */
	__u64 handled_access_fs;
	/**
	 * @handled_access_net: Bitmask of handled network actions (cf. `Network
	 * flags`_).
	 */
	__u64 handled_access_net;
	/**
	 * @scoped: Bitmask of scopes (cf. `Scope flags`_)
	 * restricting a Landlock domain from accessing outside
	 * resources (e.g. IPCs).
	 */
	__u64 scoped;
};

/**
 * DOC: landlock_create_ruleset_flags
 *
 * **Flags**
 *
 * %LANDLOCK_CREATE_RULESET_VERSION
 *     Get the highest supported Landlock ABI version (starting at 1).
 *
 * %LANDLOCK_CREATE_RULESET_ERRATA
 *     Get a bitmask of fixed issues for the current Landlock ABI version.
 */
/* clang-format off */
#define LANDLOCK_CREATE_RULESET_VERSION			(1U << 0)
#define LANDLOCK_CREATE_RULESET_ERRATA			(1U << 1)
/* clang-format on */

/**
 * DOC: landlock_restrict_self_flags
 *
 * **Flags**
 *
 * By default, denied accesses originating from programs that sandbox themselves
 * are logged via the audit subsystem. Such events typically indicate unexpected
 * behavior, such as bugs or exploitation attempts. However, to avoid excessive
 * logging, access requests denied by a domain not created by the originating
 * program are not logged by default. The rationale is that programs should know
 * their own behavior, but not necessarily the behavior of other programs.  This
 * default configuration is suitable for most programs that sandbox themselves.
 * For specific use cases, the following flags allow programs to modify this
 * default logging behavior.
 *
 * The %LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF and
 * %LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON flags apply to the newly created
 * Landlock domain.
 *
 * %LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF
 *     Disables logging of denied accesses originating from the thread creating
 *     the Landlock domain, as well as its children, as long as they continue
 *     running the same executable code (i.e., without an intervening
 *     :manpage:`execve(2)` call). This is intended for programs that execute
 *     unknown code without invoking :manpage:`execve(2)`, such as script
 *     interpreters. Programs that only sandbox themselves should not set this
 *     flag, so users can be notified of unauthorized access attempts via system
 *     logs.
 *
 * %LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON
 *     Enables logging of denied accesses after an :manpage:`execve(2)` call,
 *     providing visibility into unauthorized access attempts by newly executed
 *     programs within the created Landlock domain. This flag is recommended
 *     only when all potential executables in the domain are expected to comply
 *     with the access restrictions, as excessive audit log entries could make
 *     it more difficult to identify critical events.
 *
 * %LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF
 *     Disables logging of denied accesses originating from nested Landlock
 *     domains created by the caller or its descendants. This flag should be set
 *     according to runtime configuration, not hardcoded, to avoid suppressing
 *     important security events. It is useful for container runtimes or
 *     sandboxing tools that may launch programs which themselves create
 *     Landlock domains and could otherwise generate excessive logs. Unlike
 *     ``LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF``, this flag only affects
 *     future nested domains, not the one being created. It can also be used
 *     with a @ruleset_fd value of -1 to mute subdomain logs without creating a
 *     domain.
 */
/* clang-format off */
#define LANDLOCK_RESTRICT_SELF_LOG_SAME_EXEC_OFF		(1U << 0)
#define LANDLOCK_RESTRICT_SELF_LOG_NEW_EXEC_ON			(1U << 1)
#define LANDLOCK_RESTRICT_SELF_LOG_SUBDOMAINS_OFF		(1U << 2)
/* clang-format on */

/**
 * enum landlock_rule_type - Landlock rule type
 *
 * Argument of sys_landlock_add_rule().
 */
enum landlock_rule_type {
	/**
	 * @LANDLOCK_RULE_PATH_BENEATH: Type of a &struct
	 * landlock_path_beneath_attr .
	 */
	LANDLOCK_RULE_PATH_BENEATH = 1,
	/**
	 * @LANDLOCK_RULE_NET_PORT: Type of a &struct
	 * landlock_net_port_attr .
	 */
	LANDLOCK_RULE_NET_PORT,
};

/**
 * struct landlock_path_beneath_attr - Path hierarchy definition
 *
 * Argument of sys_landlock_add_rule().
 */
struct landlock_path_beneath_attr {
	/**
	 * @allowed_access: Bitmask of allowed actions for this file hierarchy
	 * (cf. `Filesystem flags`_).
	 */
	__u64 allowed_access;
	/**
	 * @parent_fd: File descriptor, preferably opened with ``O_PATH``,
	 * which identifies the parent directory of a file hierarchy, or just a
	 * file.
	 */
	__s32 parent_fd;
	/*
	 * This struct is packed to avoid trailing reserved members.
	 * Cf. security/landlock/syscalls.c:build_check_abi()
	 */
} __attribute__((packed));

/**
 * struct landlock_net_port_attr - Network port definition
 *
 * Argument of sys_landlock_add_rule().
 */
struct landlock_net_port_attr {
	/**
	 * @allowed_access: Bitmask of allowed network actions for a port
	 * (cf. `Network flags`_).
	 */
	__u64 allowed_access;
	/**
	 * @port: Network port in host endianness.
	 *
	 * It should be noted that port 0 passed to :manpage:`bind(2)` will bind
	 * to an available port from the ephemeral port range.  This can be
	 * configured with the ``/proc/sys/net/ipv4/ip_local_port_range`` sysctl
	 * (also used for IPv6).
	 *
	 * A Landlock rule with port 0 and the ``LANDLOCK_ACCESS_NET_BIND_TCP``
	 * right means that requesting to bind on port 0 is allowed and it will
	 * automatically translate to binding on the related port range.
	 */
	__u64 port;
};

/**
 * DOC: fs_access
 *
 * A set of actions on kernel objects may be defined by an attribute (e.g.
 * &struct landlock_path_beneath_attr) including a bitmask of access.
 *
 * Filesystem flags
 * ~~~~~~~~~~~~~~~~
 *
 * These flags enable to restrict a sandboxed process to a set of actions on
 * files and directories.  Files or directories opened before the sandboxing
 * are not subject to these restrictions.
 *
 * The following access rights apply only to files:
 *
 * - %LANDLOCK_ACCESS_FS_EXECUTE: Execute a file.
 * - %LANDLOCK_ACCESS_FS_WRITE_FILE: Open a file with write access.  When
 *   opening files for writing, you will often additionally need the
 *   %LANDLOCK_ACCESS_FS_TRUNCATE right.  In many cases, these system calls
 *   truncate existing files when overwriting them (e.g., :manpage:`creat(2)`).
 * - %LANDLOCK_ACCESS_FS_READ_FILE: Open a file with read access.
 * - %LANDLOCK_ACCESS_FS_TRUNCATE: Truncate a file with :manpage:`truncate(2)`,
 *   :manpage:`ftruncate(2)`, :manpage:`creat(2)`, or :manpage:`open(2)` with
 *   ``O_TRUNC``.  This access right is available since the third version of the
 *   Landlock ABI.
 *
 * Whether an opened file can be truncated with :manpage:`ftruncate(2)` or used
 * with `ioctl(2)` is determined during :manpage:`open(2)`, in the same way as
 * read and write permissions are checked during :manpage:`open(2)` using
 * %LANDLOCK_ACCESS_FS_READ_FILE and %LANDLOCK_ACCESS_FS_WRITE_FILE.
 *
 * A directory can receive access rights related to files or directories.  The
 * following access right is applied to the directory itself, and the
 * directories beneath it:
 *
 * - %LANDLOCK_ACCESS_FS_READ_DIR: Open a directory or list its content.
 *
 * However, the following access rights only apply to the content of a
 * directory, not the directory itself:
 *
 * - %LANDLOCK_ACCESS_FS_REMOVE_DIR: Remove an empty directory or rename one.
 * - %LANDLOCK_ACCESS_FS_REMOVE_FILE: Unlink (or rename) a file.
 * - %LANDLOCK_ACCESS_FS_MAKE_CHAR: Create (or rename or link) a character
 *   device.
 * - %LANDLOCK_ACCESS_FS_MAKE_DIR: Create (or rename) a directory.
 * - %LANDLOCK_ACCESS_FS_MAKE_REG: Create (or rename or link) a regular file.
 * - %LANDLOCK_ACCESS_FS_MAKE_SOCK: Create (or rename or link) a UNIX domain
 *   socket.
 * - %LANDLOCK_ACCESS_FS_MAKE_FIFO: Create (or rename or link) a named pipe.
 * - %LANDLOCK_ACCESS_FS_MAKE_BLOCK: Create (or rename or link) a block device.
 * - %LANDLOCK_ACCESS_FS_MAKE_SYM: Create (or rename or link) a symbolic link.
 * - %LANDLOCK_ACCESS_FS_REFER: Link or rename a file from or to a different
 *   directory (i.e. reparent a file hierarchy).
 *
 *   This access right is available since the second version of the Landlock
 *   ABI.
 *
 *   This is the only access right which is denied by default by any ruleset,
 *   even if the right is not specified as handled at ruleset creation time.
 *   The only way to make a ruleset grant this right is to explicitly allow it
 *   for a specific directory by adding a matching rule to the ruleset.
 *
 *   In particular, when using the first Landlock ABI version, Landlock will
 *   always deny attempts to reparent files between different directories.
 *
 *   In addition to the source and destination directories having the
 *   %LANDLOCK_ACCESS_FS_REFER access right, the attempted link or rename
 *   operation must meet the following constraints:
 *
 *   * The reparented file may not gain more access rights in the destination
 *     directory than it previously had in the source directory.  If this is
 *     attempted, the operation results in an ``EXDEV`` error.
 *
 *   * When linking or renaming, the ``LANDLOCK_ACCESS_FS_MAKE_*`` right for the
 *     respective file type must be granted for the destination directory.
 *     Otherwise, the operation results in an ``EACCES`` error.
 *
 *   * When renaming, the ``LANDLOCK_ACCESS_FS_REMOVE_*`` right for the
 *     respective file type must be granted for the source directory.  Otherwise,
 *     the operation results in an ``EACCES`` error.
 *
 *   If multiple requirements are not met, the ``EACCES`` error code takes
 *   precedence over ``EXDEV``.
 *
 * The following access right applies both to files and directories:
 *
 * - %LANDLOCK_ACCESS_FS_IOCTL_DEV: Invoke :manpage:`ioctl(2)` commands on an opened
 *   character or block device.
 *
 *   This access right applies to all `ioctl(2)` commands implemented by device
 *   drivers.  However, the following common IOCTL commands continue to be
 *   invokable independent of the %LANDLOCK_ACCESS_FS_IOCTL_DEV right:
 *
 *   * IOCTL commands targeting file descriptors (``FIOCLEX``, ``FIONCLEX``),
 *   * IOCTL commands targeting file descriptions (``FIONBIO``, ``FIOASYNC``),
 *   * IOCTL commands targeting file systems (``FIFREEZE``, ``FITHAW``,
 *     ``FIGETBSZ``, ``FS_IOC_GETFSUUID``, ``FS_IOC_GETFSSYSFSPATH``)
 *   * Some IOCTL commands which do not make sense when used with devices, but
 *     whose implementations are safe and return the right error codes
 *     (``FS_IOC_FIEMAP``, ``FICLONE``, ``FICLONERANGE``, ``FIDEDUPERANGE``)
 *
 *   This access right is available since the fifth version of the Landlock
 *   ABI.
 *
 * .. warning::
 *
 *   It is currently not possible to restrict some file-related actions
 *   accessible through these syscall families: :manpage:`chdir(2)`,
 *   :manpage:`stat(2)`, :manpage:`flock(2)`, :manpage:`chmod(2)`,
 *   :manpage:`chown(2)`, :manpage:`setxattr(2)`, :manpage:`utime(2)`,
 *   :manpage:`fcntl(2)`, :manpage:`access(2)`.
 *   Future Landlock evolutions will enable to restrict them.
 */
/* clang-format off */
#define LANDLOCK_ACCESS_FS_EXECUTE			(1ULL << 0)
#define LANDLOCK_ACCESS_FS_WRITE_FILE			(1ULL << 1)
#define LANDLOCK_ACCESS_FS_READ_FILE			(1ULL << 2)
#define LANDLOCK_ACCESS_FS_READ_DIR			(1ULL << 3)
#define LANDLOCK_ACCESS_FS_REMOVE_DIR			(1ULL << 4)
#define LANDLOCK_ACCESS_FS_REMOVE_FILE			(1ULL << 5)
#define LANDLOCK_ACCESS_FS_MAKE_CHAR			(1ULL << 6)
#define LANDLOCK_ACCESS_FS_MAKE_DIR			(1ULL << 7)
#define LANDLOCK_ACCESS_FS_MAKE_REG			(1ULL << 8)
#define LANDLOCK_ACCESS_FS_MAKE_SOCK			(1ULL << 9)
#define LANDLOCK_ACCESS_FS_MAKE_FIFO			(1ULL << 10)
#define LANDLOCK_ACCESS_FS_MAKE_BLOCK			(1ULL << 11)
#define LANDLOCK_ACCESS_FS_MAKE_SYM			(1ULL << 12)
#define LANDLOCK_ACCESS_FS_REFER			(1ULL << 13)
#define LANDLOCK_ACCESS_FS_TRUNCATE			(1ULL << 14)
#define LANDLOCK_ACCESS_FS_IOCTL_DEV			(1ULL << 15)
/* clang-format on */

/**
 * DOC: net_access
 *
 * Network flags
 * ~~~~~~~~~~~~~~~~
 *
 * These flags enable to restrict a sandboxed process to a set of network
 * actions.
 *
 * This is supported since Landlock ABI version 4.
 *
 * The following access rights apply to TCP port numbers:
 *
 * - %LANDLOCK_ACCESS_NET_BIND_TCP: Bind a TCP socket to a local port.
 * - %LANDLOCK_ACCESS_NET_CONNECT_TCP: Connect an active TCP socket to
 *   a remote port.
 */
/* clang-format off */
#define LANDLOCK_ACCESS_NET_BIND_TCP			(1ULL << 0)
#define LANDLOCK_ACCESS_NET_CONNECT_TCP			(1ULL << 1)
/* clang-format on */

/**
 * DOC: scope
 *
 * Scope flags
 * ~~~~~~~~~~~
 *
 * These flags enable to isolate a sandboxed process from a set of IPC actions.
 * Setting a flag for a ruleset will isolate the Landlock domain to forbid
 * connections to resources outside the domain.
 *
 * This is supported since Landlock ABI version 6.
 *
 * Scopes:
 *
 * - %LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET: Restrict a sandboxed process from
 *   connecting to an abstract UNIX socket created by a process outside the
 *   related Landlock domain (e.g., a parent domain or a non-sandboxed process).
 * - %LANDLOCK_SCOPE_SIGNAL: Restrict a sandboxed process from sending a signal
 *   to another process outside the domain.
 */
/* clang-format off */
#define LANDLOCK_SCOPE_ABSTRACT_UNIX_SOCKET		(1ULL << 0)
#define LANDLOCK_SCOPE_SIGNAL		                (1ULL << 1)
/* clang-format on*/

#endif /* _UAPI_LINUX_LANDLOCK_H */