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 "access.h" 17 #include "ruleset.h" 18 #include "setup.h" 19 20 /** 21 * struct landlock_inode_security - Inode security blob 22 * 23 * Enable to reference a &struct landlock_object tied to an inode (i.e. 24 * underlying object). 25 */ 26 struct landlock_inode_security { 27 /** 28 * @object: Weak pointer to an allocated object. All assignments of a 29 * new object are protected by the underlying inode->i_lock. However, 30 * atomically disassociating @object from the inode is only protected 31 * by @object->lock, from the time @object's usage refcount drops to 32 * zero to the time this pointer is nulled out (cf. release_inode() and 33 * hook_sb_delete()). Indeed, such disassociation doesn't require 34 * inode->i_lock thanks to the careful rcu_access_pointer() check 35 * performed by get_inode_object(). 36 */ 37 struct landlock_object __rcu *object; 38 }; 39 40 /** 41 * struct landlock_file_security - File security blob 42 * 43 * This information is populated when opening a file in hook_file_open, and 44 * tracks the relevant Landlock access rights that were available at the time 45 * of opening the file. Other LSM hooks use these rights in order to authorize 46 * operations on already opened files. 47 */ 48 struct landlock_file_security { 49 /** 50 * @allowed_access: Access rights that were available at the time of 51 * opening the file. This is not necessarily the full set of access 52 * rights available at that time, but it's the necessary subset as 53 * needed to authorize later operations on the open file. 54 */ 55 access_mask_t allowed_access; 56 /** 57 * @fown_domain: Domain of the task that set the PID that may receive a 58 * signal e.g., SIGURG when writing MSG_OOB to the related socket. 59 * This pointer is protected by the related file->f_owner->lock, as for 60 * fown_struct's members: pid, uid, and euid. 61 */ 62 struct landlock_ruleset *fown_domain; 63 }; 64 65 /** 66 * struct landlock_superblock_security - Superblock security blob 67 * 68 * Enable hook_sb_delete() to wait for concurrent calls to release_inode(). 69 */ 70 struct landlock_superblock_security { 71 /** 72 * @inode_refs: Number of pending inodes (from this superblock) that 73 * are being released by release_inode(). 74 * Cf. struct super_block->s_fsnotify_inode_refs . 75 */ 76 atomic_long_t inode_refs; 77 }; 78 79 static inline struct landlock_file_security * 80 landlock_file(const struct file *const file) 81 { 82 return file->f_security + landlock_blob_sizes.lbs_file; 83 } 84 85 static inline struct landlock_inode_security * 86 landlock_inode(const struct inode *const inode) 87 { 88 return inode->i_security + landlock_blob_sizes.lbs_inode; 89 } 90 91 static inline struct landlock_superblock_security * 92 landlock_superblock(const struct super_block *const superblock) 93 { 94 return superblock->s_security + landlock_blob_sizes.lbs_superblock; 95 } 96 97 __init void landlock_add_fs_hooks(void); 98 99 int landlock_append_fs_rule(struct landlock_ruleset *const ruleset, 100 const struct path *const path, 101 access_mask_t access_hierarchy); 102 103 #endif /* _SECURITY_LANDLOCK_FS_H */ 104