Add Landlock, a new LSM from Mickaël Salaün <mic@linux.microsoft.com>
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Merge tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull Landlock LSM from James Morris:
"Add Landlock, a new LSM from Mickaël Salaün.
Briefly, Landlock provides for unprivileged application sandboxing.
From Mickaël's cover letter:
"The goal of Landlock is to enable to restrict ambient rights (e.g.
global filesystem access) for a set of processes. Because Landlock
is a stackable LSM [1], it makes possible to create safe security
sandboxes as new security layers in addition to the existing
system-wide access-controls. This kind of sandbox is expected to
help mitigate the security impact of bugs or unexpected/malicious
behaviors in user-space applications. Landlock empowers any
process, including unprivileged ones, to securely restrict
themselves.
Landlock is inspired by seccomp-bpf but instead of filtering
syscalls and their raw arguments, a Landlock rule can restrict the
use of kernel objects like file hierarchies, according to the
kernel semantic. Landlock also takes inspiration from other OS
sandbox mechanisms: XNU Sandbox, FreeBSD Capsicum or OpenBSD
Pledge/Unveil.
In this current form, Landlock misses some access-control features.
This enables to minimize this patch series and ease review. This
series still addresses multiple use cases, especially with the
combined use of seccomp-bpf: applications with built-in sandboxing,
init systems, security sandbox tools and security-oriented APIs [2]"
The cover letter and v34 posting is here:
https://lore.kernel.org/linux-security-module/20210422154123.13086-1-mic@digikod.net/
See also:
https://landlock.io/
This code has had extensive design discussion and review over several
years"
Link: https://lore.kernel.org/lkml/50db058a-7dde-441b-a7f9-f6837fe8b69f@schaufler-ca.com/ [1]
Link: https://lore.kernel.org/lkml/f646e1c7-33cf-333f-070c-0a40ad0468cd@digikod.net/ [2]
* tag 'landlock_v34' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
landlock: Enable user space to infer supported features
landlock: Add user and kernel documentation
samples/landlock: Add a sandbox manager example
selftests/landlock: Add user space tests
landlock: Add syscall implementations
arch: Wire up Landlock syscalls
fs,security: Add sb_delete hook
landlock: Support filesystem access-control
LSM: Infrastructure management of the superblock
landlock: Add ptrace restrictions
landlock: Set up the security framework and manage credentials
landlock: Add ruleset and domain management
landlock: Add object management
This commit is contained in:
Linus Torvalds
commit
17ae69aba8
72 changed files with 6987 additions and 77 deletions
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@ -59,6 +59,7 @@ LSM_HOOK(int, 0, fs_context_dup, struct fs_context *fc,
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LSM_HOOK(int, -ENOPARAM, fs_context_parse_param, struct fs_context *fc,
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struct fs_parameter *param)
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LSM_HOOK(int, 0, sb_alloc_security, struct super_block *sb)
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LSM_HOOK(void, LSM_RET_VOID, sb_delete, struct super_block *sb)
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LSM_HOOK(void, LSM_RET_VOID, sb_free_security, struct super_block *sb)
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LSM_HOOK(void, LSM_RET_VOID, sb_free_mnt_opts, void *mnt_opts)
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LSM_HOOK(int, 0, sb_eat_lsm_opts, char *orig, void **mnt_opts)
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@ -108,6 +108,9 @@
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* allocated.
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* @sb contains the super_block structure to be modified.
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* Return 0 if operation was successful.
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* @sb_delete:
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* Release objects tied to a superblock (e.g. inodes).
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* @sb contains the super_block structure being released.
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* @sb_free_security:
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* Deallocate and clear the sb->s_security field.
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* @sb contains the super_block structure to be modified.
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@ -1585,6 +1588,7 @@ struct lsm_blob_sizes {
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int lbs_cred;
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int lbs_file;
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int lbs_inode;
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int lbs_superblock;
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int lbs_ipc;
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int lbs_msg_msg;
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int lbs_task;
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@ -291,6 +291,7 @@ void security_bprm_committed_creds(struct linux_binprm *bprm);
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int security_fs_context_dup(struct fs_context *fc, struct fs_context *src_fc);
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int security_fs_context_parse_param(struct fs_context *fc, struct fs_parameter *param);
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int security_sb_alloc(struct super_block *sb);
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void security_sb_delete(struct super_block *sb);
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void security_sb_free(struct super_block *sb);
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void security_free_mnt_opts(void **mnt_opts);
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int security_sb_eat_lsm_opts(char *options, void **mnt_opts);
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@ -633,6 +634,9 @@ static inline int security_sb_alloc(struct super_block *sb)
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return 0;
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}
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static inline void security_sb_delete(struct super_block *sb)
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{ }
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static inline void security_sb_free(struct super_block *sb)
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{ }
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@ -69,6 +69,8 @@ struct io_uring_params;
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struct clone_args;
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struct open_how;
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struct mount_attr;
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struct landlock_ruleset_attr;
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enum landlock_rule_type;
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#include <linux/types.h>
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#include <linux/aio_abi.h>
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@ -1043,6 +1045,11 @@ asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
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siginfo_t __user *info,
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unsigned int flags);
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asmlinkage long sys_pidfd_getfd(int pidfd, int fd, unsigned int flags);
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asmlinkage long sys_landlock_create_ruleset(const struct landlock_ruleset_attr __user *attr,
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size_t size, __u32 flags);
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asmlinkage long sys_landlock_add_rule(int ruleset_fd, enum landlock_rule_type rule_type,
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const void __user *rule_attr, __u32 flags);
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asmlinkage long sys_landlock_restrict_self(int ruleset_fd, __u32 flags);
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/*
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* Architecture-specific system calls
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@ -866,8 +866,15 @@ __SYSCALL(__NR_mount_setattr, sys_mount_setattr)
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#define __NR_quotactl_path 443
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__SYSCALL(__NR_quotactl_path, sys_quotactl_path)
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#define __NR_landlock_create_ruleset 444
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__SYSCALL(__NR_landlock_create_ruleset, sys_landlock_create_ruleset)
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#define __NR_landlock_add_rule 445
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__SYSCALL(__NR_landlock_add_rule, sys_landlock_add_rule)
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#define __NR_landlock_restrict_self 446
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__SYSCALL(__NR_landlock_restrict_self, sys_landlock_restrict_self)
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#undef __NR_syscalls
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#define __NR_syscalls 444
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#define __NR_syscalls 447
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/*
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* 32 bit systems traditionally used different
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137
include/uapi/linux/landlock.h
Normal file
137
include/uapi/linux/landlock.h
Normal file
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@ -0,0 +1,137 @@
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/* 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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* sys_landlock_create_ruleset() flags:
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*
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* - %LANDLOCK_CREATE_RULESET_VERSION: Get the highest supported Landlock ABI
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* version.
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*/
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#define LANDLOCK_CREATE_RULESET_VERSION (1U << 0)
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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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