security/landlock/access.h

   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
  31 typedef u16 access_mask_t;
  32
  33 /* Makes sure all filesystem access rights can be stored. */
  34 static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_FS);
  35 /* Makes sure all network access rights can be stored. */
  36 static_assert(BITS_PER_TYPE(access_mask_t) >= LANDLOCK_NUM_ACCESS_NET);
  37 /* Makes sure all scoped rights can be stored. */
  38 static_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. */
  40 static_assert(sizeof(unsigned long) >= sizeof(access_mask_t));
  41
  42 /* Ruleset access masks. */
  43 struct 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
  49 union access_masks_all {
  50         struct access_masks masks;
  51         u32 all;
  52 };
  53
  54 /* Makes sure all fields are covered. */
  55 static_assert(sizeof(typeof_member(union access_masks_all, masks)) ==
  56               sizeof(typeof_member(union access_masks_all, all)));
  57
  58 typedef u16 layer_mask_t;
  59
  60 /* Makes sure all layers can be checked. */
  61 static_assert(BITS_PER_TYPE(layer_mask_t) >= LANDLOCK_MAX_NUM_LAYERS);
  62
  63 /* Upgrades with all initially denied by default access rights. */
  64 static inline struct access_masks
  65 landlock_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 */