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 * @fown_domain: Domain of the task that set the PID that may receive a 57 * signal e.g., SIGURG when writing MSG_OOB to the related socket. 58 * This pointer is protected by the related file->f_owner->lock, as for 59 * fown_struct's members: pid, uid, and euid. 60 */ 61 struct landlock_ruleset *fown_domain; 62 }; 63 64 /** 65 * struct landlock_superblock_security - Superblock security blob 66 * 67 * Enable hook_sb_delete() to wait for concurrent calls to release_inode(). 68 */ 69 struct landlock_superblock_security { 70 /** 71 * @inode_refs: Number of pending inodes (from this superblock) that 72 * are being released by release_inode(). 73 * Cf. struct super_block->s_fsnotify_inode_refs . 74 */ 75 atomic_long_t inode_refs; 76 }; 77 78 static inline struct landlock_file_security * 79 landlock_file(const struct file *const file) 80 { 81 return file->f_security + landlock_blob_sizes.lbs_file; 82 } 83 84 static inline struct landlock_inode_security * 85 landlock_inode(const struct inode *const inode) 86 { 87 return inode->i_security + landlock_blob_sizes.lbs_inode; 88 } 89 90 static inline struct landlock_superblock_security * 91 landlock_superblock(const struct super_block *const superblock) 92 { 93 return superblock->s_security + landlock_blob_sizes.lbs_superblock; 94 } 95 96 __init void landlock_add_fs_hooks(void); 97 98 int landlock_append_fs_rule(struct landlock_ruleset *const ruleset, 99 const struct path *const path, 100 access_mask_t access_hierarchy); 101 102 #endif /* _SECURITY_LANDLOCK_FS_H */ 103