265885daf3
These 3 system calls are designed to be used by unprivileged processes to sandbox themselves: * landlock_create_ruleset(2): Creates a ruleset and returns its file descriptor. * landlock_add_rule(2): Adds a rule (e.g. file hierarchy access) to a ruleset, identified by the dedicated file descriptor. * landlock_restrict_self(2): Enforces a ruleset on the calling thread and its future children (similar to seccomp). This syscall has the same usage restrictions as seccomp(2): the caller must have the no_new_privs attribute set or have CAP_SYS_ADMIN in the current user namespace. All these syscalls have a "flags" argument (not currently used) to enable extensibility. Here are the motivations for these new syscalls: * A sandboxed process may not have access to file systems, including /dev, /sys or /proc, but it should still be able to add more restrictions to itself. * Neither prctl(2) nor seccomp(2) (which was used in a previous version) fit well with the current definition of a Landlock security policy. All passed structs (attributes) are checked at build time to ensure that they don't contain holes and that they are aligned the same way for each architecture. See the user and kernel documentation for more details (provided by a following commit): * Documentation/userspace-api/landlock.rst * Documentation/security/landlock.rst Cc: Arnd Bergmann <arnd@arndb.de> Cc: James Morris <jmorris@namei.org> Cc: Jann Horn <jannh@google.com> Cc: Kees Cook <keescook@chromium.org> Signed-off-by: Mickaël Salaün <mic@linux.microsoft.com> Acked-by: Serge Hallyn <serge@hallyn.com> Link: https://lore.kernel.org/r/20210422154123.13086-9-mic@digikod.net Signed-off-by: James Morris <jamorris@linux.microsoft.com>
129 lines
4.4 KiB
C
129 lines
4.4 KiB
C
/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
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/*
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* Landlock - User space API
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*
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* Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
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* Copyright © 2018-2020 ANSSI
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*/
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#ifndef _UAPI_LINUX_LANDLOCK_H
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#define _UAPI_LINUX_LANDLOCK_H
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#include <linux/types.h>
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/**
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* struct landlock_ruleset_attr - Ruleset definition
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*
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* Argument of sys_landlock_create_ruleset(). This structure can grow in
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* future versions.
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*/
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struct landlock_ruleset_attr {
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/**
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* @handled_access_fs: Bitmask of actions (cf. `Filesystem flags`_)
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* that is handled by this ruleset and should then be forbidden if no
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* rule explicitly allow them. This is needed for backward
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* compatibility reasons.
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*/
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__u64 handled_access_fs;
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};
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/**
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* enum landlock_rule_type - Landlock rule type
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*
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* Argument of sys_landlock_add_rule().
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*/
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enum landlock_rule_type {
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/**
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* @LANDLOCK_RULE_PATH_BENEATH: Type of a &struct
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* landlock_path_beneath_attr .
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*/
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LANDLOCK_RULE_PATH_BENEATH = 1,
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};
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/**
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* struct landlock_path_beneath_attr - Path hierarchy definition
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*
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* Argument of sys_landlock_add_rule().
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*/
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struct landlock_path_beneath_attr {
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/**
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* @allowed_access: Bitmask of allowed actions for this file hierarchy
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* (cf. `Filesystem flags`_).
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*/
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__u64 allowed_access;
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/**
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* @parent_fd: File descriptor, open with ``O_PATH``, which identifies
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* the parent directory of a file hierarchy, or just a file.
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*/
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__s32 parent_fd;
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/*
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* This struct is packed to avoid trailing reserved members.
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* Cf. security/landlock/syscalls.c:build_check_abi()
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*/
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} __attribute__((packed));
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/**
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* DOC: fs_access
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*
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* A set of actions on kernel objects may be defined by an attribute (e.g.
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* &struct landlock_path_beneath_attr) including a bitmask of access.
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*
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* Filesystem flags
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* ~~~~~~~~~~~~~~~~
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*
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* These flags enable to restrict a sandboxed process to a set of actions on
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* files and directories. Files or directories opened before the sandboxing
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* are not subject to these restrictions.
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*
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* A file can only receive these access rights:
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*
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* - %LANDLOCK_ACCESS_FS_EXECUTE: Execute a file.
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* - %LANDLOCK_ACCESS_FS_WRITE_FILE: Open a file with write access.
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* - %LANDLOCK_ACCESS_FS_READ_FILE: Open a file with read access.
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*
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* A directory can receive access rights related to files or directories. The
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* following access right is applied to the directory itself, and the
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* directories beneath it:
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*
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* - %LANDLOCK_ACCESS_FS_READ_DIR: Open a directory or list its content.
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*
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* However, the following access rights only apply to the content of a
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* directory, not the directory itself:
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*
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* - %LANDLOCK_ACCESS_FS_REMOVE_DIR: Remove an empty directory or rename one.
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* - %LANDLOCK_ACCESS_FS_REMOVE_FILE: Unlink (or rename) a file.
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* - %LANDLOCK_ACCESS_FS_MAKE_CHAR: Create (or rename or link) a character
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* device.
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* - %LANDLOCK_ACCESS_FS_MAKE_DIR: Create (or rename) a directory.
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* - %LANDLOCK_ACCESS_FS_MAKE_REG: Create (or rename or link) a regular file.
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* - %LANDLOCK_ACCESS_FS_MAKE_SOCK: Create (or rename or link) a UNIX domain
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* socket.
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* - %LANDLOCK_ACCESS_FS_MAKE_FIFO: Create (or rename or link) a named pipe.
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* - %LANDLOCK_ACCESS_FS_MAKE_BLOCK: Create (or rename or link) a block device.
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* - %LANDLOCK_ACCESS_FS_MAKE_SYM: Create (or rename or link) a symbolic link.
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*
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* .. warning::
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*
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* It is currently not possible to restrict some file-related actions
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* accessible through these syscall families: :manpage:`chdir(2)`,
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* :manpage:`truncate(2)`, :manpage:`stat(2)`, :manpage:`flock(2)`,
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* :manpage:`chmod(2)`, :manpage:`chown(2)`, :manpage:`setxattr(2)`,
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* :manpage:`utime(2)`, :manpage:`ioctl(2)`, :manpage:`fcntl(2)`,
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* :manpage:`access(2)`.
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* Future Landlock evolutions will enable to restrict them.
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*/
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#define LANDLOCK_ACCESS_FS_EXECUTE (1ULL << 0)
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#define LANDLOCK_ACCESS_FS_WRITE_FILE (1ULL << 1)
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#define LANDLOCK_ACCESS_FS_READ_FILE (1ULL << 2)
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#define LANDLOCK_ACCESS_FS_READ_DIR (1ULL << 3)
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#define LANDLOCK_ACCESS_FS_REMOVE_DIR (1ULL << 4)
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#define LANDLOCK_ACCESS_FS_REMOVE_FILE (1ULL << 5)
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#define LANDLOCK_ACCESS_FS_MAKE_CHAR (1ULL << 6)
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#define LANDLOCK_ACCESS_FS_MAKE_DIR (1ULL << 7)
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#define LANDLOCK_ACCESS_FS_MAKE_REG (1ULL << 8)
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#define LANDLOCK_ACCESS_FS_MAKE_SOCK (1ULL << 9)
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#define LANDLOCK_ACCESS_FS_MAKE_FIFO (1ULL << 10)
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#define LANDLOCK_ACCESS_FS_MAKE_BLOCK (1ULL << 11)
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#define LANDLOCK_ACCESS_FS_MAKE_SYM (1ULL << 12)
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#endif /* _UAPI_LINUX_LANDLOCK_H */
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