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 */ 29 struct 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 */ 51 struct 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 */ 87 static_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 */ 98 struct 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 }; 106 107 static inline struct landlock_file_security * 108 landlock_file(const struct file *const file) 109 { 110 return file->f_security + landlock_blob_sizes.lbs_file; 111 } 112 113 static inline struct landlock_inode_security * 114 landlock_inode(const struct inode *const inode) 115 { 116 return inode->i_security + landlock_blob_sizes.lbs_inode; 117 } 118 119 static inline struct landlock_superblock_security * 120 landlock_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); 126 127 int 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 */ 132