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 *
landlock_file(const struct file * const file)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 *
landlock_inode(const struct inode * const inode)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 *
landlock_superblock(const struct super_block * const superblock)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