1 /* SPDX-License-Identifier: GPL-2.0-only */
2 /*
3 * Landlock LSM - Filesystem management and hooks
4 *
5 * Copyright © 2017-2020 Mickaël Salaün <mic@digikod.net>
6 * Copyright © 2018-2020 ANSSI
7 */
8
9 #ifndef _SECURITY_LANDLOCK_FS_H
10 #define _SECURITY_LANDLOCK_FS_H
11
12 #include <linux/fs.h>
13 #include <linux/init.h>
14 #include <linux/rcupdate.h>
15
16 #include "ruleset.h"
17 #include "setup.h"
18
19 /**
20 * struct landlock_inode_security - Inode security blob
21 *
22 * Enable to reference a &struct landlock_object tied to an inode (i.e.
23 * underlying object).
24 */
25 struct landlock_inode_security {
26 /**
27 * @object: Weak pointer to an allocated object. All assignments of a
28 * new object are protected by the underlying inode->i_lock. However,
29 * atomically disassociating @object from the inode is only protected
30 * by @object->lock, from the time @object's usage refcount drops to
31 * zero to the time this pointer is nulled out (cf. release_inode() and
32 * hook_sb_delete()). Indeed, such disassociation doesn't require
33 * inode->i_lock thanks to the careful rcu_access_pointer() check
34 * performed by get_inode_object().
35 */
36 struct landlock_object __rcu *object;
37 };
38
39 /**
40 * struct landlock_file_security - File security blob
41 *
42 * This information is populated when opening a file in hook_file_open, and
43 * tracks the relevant Landlock access rights that were available at the time
44 * of opening the file. Other LSM hooks use these rights in order to authorize
45 * operations on already opened files.
46 */
47 struct landlock_file_security {
48 /**
49 * @allowed_access: Access rights that were available at the time of
50 * opening the file. This is not necessarily the full set of access
51 * rights available at that time, but it's the necessary subset as
52 * needed to authorize later operations on the open file.
53 */
54 access_mask_t allowed_access;
55 };
56
57 /**
58 * struct landlock_superblock_security - Superblock security blob
59 *
60 * Enable hook_sb_delete() to wait for concurrent calls to release_inode().
61 */
62 struct landlock_superblock_security {
63 /**
64 * @inode_refs: Number of pending inodes (from this superblock) that
65 * are being released by release_inode().
66 * Cf. struct super_block->s_fsnotify_inode_refs .
67 */
68 atomic_long_t inode_refs;
69 };
70
71 static inline struct landlock_file_security *
72 landlock_file(const struct file *const file)
73 {
74 return file->f_security + landlock_blob_sizes.lbs_file;
75 }
76
77 static inline struct landlock_inode_security *
78 landlock_inode(const struct inode *const inode)
79 {
80 return inode->i_security + landlock_blob_sizes.lbs_inode;
81 }
82
83 static inline struct landlock_superblock_security *
84 landlock_superblock(const struct super_block *const superblock)
85 {
86 return superblock->s_security + landlock_blob_sizes.lbs_superblock;
87 }
88
89 __init void landlock_add_fs_hooks(void);
90
91 int landlock_append_fs_rule(struct landlock_ruleset *const ruleset,
92 const struct path *const path,
93 access_mask_t access_hierarchy);
94
95 #endif /* _SECURITY_LANDLOCK_FS_H */
96
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.