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_superblock_security - Superblock security blob
41  *
42  * Enable hook_sb_delete() to wait for concurrent calls to release_inode().
43  */
44 struct landlock_superblock_security {
45 	/**
46 	 * @inode_refs: Number of pending inodes (from this superblock) that
47 	 * are being released by release_inode().
48 	 * Cf. struct super_block->s_fsnotify_inode_refs .
49 	 */
50 	atomic_long_t inode_refs;
51 };
52 
53 static inline struct landlock_inode_security *
landlock_inode(const struct inode * const inode)54 landlock_inode(const struct inode *const inode)
55 {
56 	return inode->i_security + landlock_blob_sizes.lbs_inode;
57 }
58 
59 static inline struct landlock_superblock_security *
landlock_superblock(const struct super_block * const superblock)60 landlock_superblock(const struct super_block *const superblock)
61 {
62 	return superblock->s_security + landlock_blob_sizes.lbs_superblock;
63 }
64 
65 __init void landlock_add_fs_hooks(void);
66 
67 int landlock_append_fs_rule(struct landlock_ruleset *const ruleset,
68 			    const struct path *const path,
69 			    access_mask_t access_hierarchy);
70 
71 #endif /* _SECURITY_LANDLOCK_FS_H */
72