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1/* SPDX-License-Identifier: GPL-2.0-only */
2/*
3 * Landlock LSM - Access types and helpers
4 *
5 * Copyright © 2016-2020 Mickaël Salaün <mic@digikod.net>
6 * Copyright © 2018-2020 ANSSI
7 * Copyright © 2024-2025 Microsoft Corporation
8 */
9
10#ifndef _SECURITY_LANDLOCK_ACCESS_H
11#define _SECURITY_LANDLOCK_ACCESS_H
12
13#include <linux/bitops.h>
14#include <linux/build_bug.h>
15#include <linux/kernel.h>
16#include <uapi/linux/landlock.h>
17
18#include "limits.h"
19
20/*
21 * All access rights that are denied by default whether they are handled or not
22 * by a ruleset/layer. This must be ORed with all ruleset->access_masks[]
23 * entries when we need to get the absolute handled access masks, see
24 * landlock_upgrade_handled_access_masks().
25 */
26/* clang-format off */
27#define _LANDLOCK_ACCESS_FS_INITIALLY_DENIED ( \
28 LANDLOCK_ACCESS_FS_REFER)
29/* clang-format on */
30
31typedef u16 access_mask_t;
32
33/* Makes sure all filesystem access rights can be stored. */
34static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
35/* Makes sure all network access rights can be stored. */
36static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET);
37/* Makes sure all scoped rights can be stored. */
38static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_SCOPE);
39/* Makes sure for_each_set_bit() and for_each_clear_bit() calls are OK. */
40static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
41
42/* Ruleset access masks. */
43struct access_masks {
44 access_mask_t fs : LANDLOCK_NUM_ACCESS_FS;
45 access_mask_t net : LANDLOCK_NUM_ACCESS_NET;
46 access_mask_t scope : LANDLOCK_NUM_SCOPE;
47};
48
49union access_masks_all {
50 struct access_masks masks;
51 u32 all;
52};
53
54/* Makes sure all fields are covered. */
55static_assert(sizeof(typeof_member(union access_masks_all, masks)) ==
56 sizeof(typeof_member(union access_masks_all, all)));
57
58typedef u16 layer_mask_t;
59
60/* Makes sure all layers can be checked. */
61static_assert(BITS_PER_TYPE(layer_mask_t) >= LANDLOCK_MAX_NUM_LAYERS);
62
63/* Upgrades with all initially denied by default access rights. */
64static inline struct access_masks
65landlock_upgrade_handled_access_masks(struct access_masks access_masks)
66{
67 /*
68 * All access rights that are denied by default whether they are
69 * explicitly handled or not.
70 */
71 if (access_masks.fs)
72 access_masks.fs |= _LANDLOCK_ACCESS_FS_INITIALLY_DENIED;
73
74 return access_masks;
75}
76
77#endif /* _SECURITY_LANDLOCK_ACCESS_H */