1 /*
2 * Copyright (c) 2022 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28 #ifndef _MACH_VM_MEMTAG_H_
29 #define _MACH_VM_MEMTAG_H_
30
31 #ifdef KERNEL
32
33 #if __arm64__
34 #include <pexpert/arm64/board_config.h>
35 #endif /* __arm64__ */
36
37 #include <kern/assert.h>
38 #include <mach/vm_types.h>
39 #include <sys/_types/_caddr_t.h>
40
41
42 #if KASAN_TBI
43 #define ENABLE_MEMTAG_INTERFACES 1
44 #define ENABLE_MEMTAG_MANIPULATION_API 1
45 #endif
46
47
48
49
50 #if defined(ENABLE_MEMTAG_INTERFACES)
51
52 __BEGIN_DECLS
53
54 /* Zero-out a tagged memory region performing the minimum set of mandatory checks. */
55 extern void vm_memtag_fast_checked_bzero(void *tagged_buf, vm_size_t n);
56
57 /*
58 * Given a naked address, extract the metadata from memory and add it to
59 * the correct pointer metadata.
60 */
61 extern vm_map_address_t vm_memtag_load_tag(vm_map_address_t naked_address);
62
63 /*
64 * Given a tagged pointer and a size, update the associated backing metadata
65 * to match the pointer metadata.
66 */
67 extern void
68 vm_memtag_store_tag(caddr_t tagged_address, vm_size_t size);
69
70 /* Randomly assign a tag to the current chunk of memory. */
71 extern caddr_t
72 vm_memtag_generate_and_store_tag(caddr_t address, vm_size_t size);
73
74 /*
75 * When passed a tagged pointer, verify that the pointer metadata matches
76 * the backing storage metadata.
77 */
78 extern void
79 vm_memtag_verify_tag(vm_map_address_t tagged_address);
80
81 /*
82 * Copy metadata between two mappings whenever we are relocating memory.
83 */
84 extern void
85 vm_memtag_relocate_tags(vm_address_t new_address, vm_address_t old_address, vm_size_t size);
86
87 /* Temporarily enable/disable memtag checking. */
88 extern void
89 vm_memtag_enable_checking(void);
90 extern void
91 vm_memtag_disable_checking(void);
92
93 /*
94 * Zeroing operations traditionally happen on large amount of memory (often pages)
95 * and tend to span over several different regions with different memtags. Implement
96 * variants of bzero that capture both performing this operation without checking
97 * (vm_memtag_bzero_unchecked) and by optimizing checking behavior (vm_memtag_bzero_fast_checked)
98 */
99 extern void
100 vm_memtag_bzero_fast_checked(void *tagged_buf, vm_size_t n);
101 extern void
102 vm_memtag_bzero_unchecked(void *tagged_buf, vm_size_t n);
103
104 __END_DECLS
105
106 #else /* ENABLE_MEMTAG_INTERFACES */
107
108
109 #if KASAN_TBI
110 #error "vm_memtag interfaces should be defined whenever KASAN-TBI is enabled"
111 #endif /* KASAN_TBI */
112
113 #define vm_memtag_fast_checked_bzero(p, s) bzero(p, s)
114 #define vm_memtag_load_tag(a) (a)
115 #define vm_memtag_store_tag(a, s) do { } while (0)
116 #define vm_memtag_generate_and_store_tag(a, s) (a)
117 #define vm_memtag_relocate_tags(n, o, l) do { } while (0)
118 #define vm_memtag_enable_checking() do { } while (0)
119 #define vm_memtag_disable_checking() do { } while (0)
120 #define vm_memtag_bzero_fast_checked(b, n) bzero(b, n)
121 #define vm_memtag_bzero_unchecked(b, n) bzero(b, n)
122
123 #endif /* ENABLE_MEMTAG_INTERFACES */
124
125 #if defined(ENABLE_MEMTAG_MANIPULATION_API)
126
127 __BEGIN_DECLS
128 /*
129 * Helper functions to manipulate tagged pointers. If more implementors of
130 * the vm_memtag interface beyond KASAN-TBI were to come, then these definitions
131 * should be ifdef guarded properly.
132 */
133
134 #define VM_MEMTAG_PTR_SIZE 56
135 #define VM_MEMTAG_TAG_SIZE 4
136 #define VM_MEMTAG_UPPER_SIZE 4
137
138 typedef uint8_t vm_memtag_t;
139
140 union vm_memtag_ptr {
141 long value;
142
143 struct {
144 long ptr_bits: VM_MEMTAG_PTR_SIZE;
145 vm_memtag_t ptr_tag: VM_MEMTAG_TAG_SIZE;
146 long ptr_upper: VM_MEMTAG_UPPER_SIZE;
147 };
148 };
149
150 static inline vm_map_address_t
vm_memtag_insert_tag(vm_map_address_t naked_ptr,vm_memtag_t tag)151 vm_memtag_insert_tag(vm_map_address_t naked_ptr, vm_memtag_t tag)
152 {
153 union vm_memtag_ptr p = {
154 .value = (long)naked_ptr,
155 };
156
157 p.ptr_tag = tag;
158 return (vm_map_address_t)p.value;
159 }
160
161 static inline vm_memtag_t
vm_memtag_extract_tag(vm_map_address_t tagged_ptr)162 vm_memtag_extract_tag(vm_map_address_t tagged_ptr)
163 {
164 union vm_memtag_ptr p = {
165 .value = (long)tagged_ptr,
166 };
167
168 return p.ptr_tag;
169 }
170
171 /*
172 * when passed a tagged pointer, strip away only the tag bits with their canonical
173 * value. Since these are used in a number of frequently called checks
174 * (e.g. when packing VM pointers), the following definition hardcodes the
175 * tag value to achieve optimal codegen and no external calls.
176 */
177 #define vm_memtag_canonicalize_kernel(addr) vm_memtag_insert_tag(addr, 0xF)
178 #define vm_memtag_canonicalize_user(addr) vm_memtag_insert_tag(addr, 0x0)
179
180 extern vm_map_address_t
181 vm_memtag_canonicalize(vm_map_t map, vm_map_address_t addr);
182
183 __END_DECLS
184
185 #else /* ENABLE_MEMTAG_MANIPULATION_API */
186
187
188 #if KASAN_TBI
189 #error "vm_memtag manipulation APIs should be defined whenever KASAN-TBI is enabled"
190 #endif /* KASAN_TBI */
191
192 #define vm_memtag_insert_tag(p, t) (p)
193 #define vm_memtag_extract_tag(p) (0xF)
194 #define vm_memtag_canonicalize(m, a) (a)
195 #define vm_memtag_canonicalize_user(a) (a)
196 #define vm_memtag_canonicalize_kernel(a) (a)
197
198 #endif /* ENABLE_MEMTAG_MANIPULATION_API */
199
200 #endif /* KERNEL */
201
202 #endif /* _MACH_VM_MEMTAG_H_ */
203