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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Landlock - Filesystem management and hooks
4 *
5 * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
6 * Copyright © 2018-2020 ANSSI
7 * Copyright © 2024-2025 Microsoft Corporation
8 */
9
10#ifndef _SECURITY_LANDLOCK_FS_H
11#define _SECURITY_LANDLOCK_FS_H
12
13#include <linux/build_bug.h>
14#include <linux/fs.h>
15#include <linux/init.h>
16#include <linux/rcupdate.h>
17
18#include "access.h"
19#include "cred.h"
20#include "ruleset.h"
21#include "setup.h"
22
23/**
24 * struct landlock_inode_security - Inode security blob
25 *
26 * Enable to reference a &struct landlock_object tied to an inode (i.e.
27 * underlying object).
28 */
29struct landlock_inode_security {
30 /**
31 * @object: Weak pointer to an allocated object. All assignments of a
32 * new object are protected by the underlying inode->i_lock. However,
33 * atomically disassociating @object from the inode is only protected
34 * by @object->lock, from the time @object's usage refcount drops to
35 * zero to the time this pointer is nulled out (cf. release_inode() and
36 * hook_sb_delete()). Indeed, such disassociation doesn't require
37 * inode->i_lock thanks to the careful rcu_access_pointer() check
38 * performed by get_inode_object().
39 */
40 struct landlock_object __rcu *object;
41};
42
43/**
44 * struct landlock_file_security - File security blob
45 *
46 * This information is populated when opening a file in hook_file_open, and
47 * tracks the relevant Landlock access rights that were available at the time
48 * of opening the file. Other LSM hooks use these rights in order to authorize
49 * operations on already opened files.
50 */
51struct landlock_file_security {
52 /**
53 * @allowed_access: Access rights that were available at the time of
54 * opening the file. This is not necessarily the full set of access
55 * rights available at that time, but it's the necessary subset as
56 * needed to authorize later operations on the open file.
57 */
58 access_mask_t allowed_access;
59
60#ifdef CONFIG_AUDIT
61 /**
62 * @deny_masks: Domain layer levels that deny an optional access (see
63 * _LANDLOCK_ACCESS_FS_OPTIONAL).
64 */
65 deny_masks_t deny_masks;
66 /**
67 * @fown_layer: Layer level of @fown_subject->domain with
68 * LANDLOCK_SCOPE_SIGNAL.
69 */
70 u8 fown_layer;
71#endif /* CONFIG_AUDIT */
72
73 /**
74 * @fown_subject: Landlock credential of the task that set the PID that
75 * may receive a signal e.g., SIGURG when writing MSG_OOB to the
76 * related socket. This pointer is protected by the related
77 * file->f_owner->lock, as for fown_struct's members: pid, uid, and
78 * euid.
79 */
80 struct landlock_cred_security fown_subject;
81};
82
83#ifdef CONFIG_AUDIT
84
85/* Makes sure all layers can be identified. */
86/* clang-format off */
87static_assert((typeof_member(struct landlock_file_security, fown_layer))~0 >=
88 LANDLOCK_MAX_NUM_LAYERS);
89/* clang-format off */
90
91#endif /* CONFIG_AUDIT */
92
93/**
94 * struct landlock_superblock_security - Superblock security blob
95 *
96 * Enable hook_sb_delete() to wait for concurrent calls to release_inode().
97 */
98struct landlock_superblock_security {
99 /**
100 * @inode_refs: Number of pending inodes (from this superblock) that
101 * are being released by release_inode().
102 * Cf. struct super_block->s_fsnotify_inode_refs .
103 */
104 atomic_long_t inode_refs;
105};
106
107static inline struct landlock_file_security *
108landlock_file(const struct file *const file)
109{
110 return file->f_security + landlock_blob_sizes.lbs_file;
111}
112
113static inline struct landlock_inode_security *
114landlock_inode(const struct inode *const inode)
115{
116 return inode->i_security + landlock_blob_sizes.lbs_inode;
117}
118
119static inline struct landlock_superblock_security *
120landlock_superblock(const struct super_block *const superblock)
121{
122 return superblock->s_security + landlock_blob_sizes.lbs_superblock;
123}
124
125__init void landlock_add_fs_hooks(void);
126
127int landlock_append_fs_rule(struct landlock_ruleset *const ruleset,
128 const struct path *const path,
129 access_mask_t access_hierarchy);
130
131#endif /* _SECURITY_LANDLOCK_FS_H */