1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * This file contains core generic KASAN code.
4 *
5 * Copyright (c) 2014 Samsung Electronics Co., Ltd.
6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
7 *
8 * Some code borrowed from https://github.com/xairy/kasan-prototype by
9 * Andrey Konovalov <andreyknvl@gmail.com>
10 *
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2 as
13 * published by the Free Software Foundation.
14 *
15 */
16
17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
18
19 #include <linux/export.h>
20 #include <linux/interrupt.h>
21 #include <linux/init.h>
22 #include <linux/kasan.h>
23 #include <linux/kernel.h>
24 #include <linux/kmemleak.h>
25 #include <linux/linkage.h>
26 #include <linux/memblock.h>
27 #include <linux/memory.h>
28 #include <linux/mm.h>
29 #include <linux/module.h>
30 #include <linux/printk.h>
31 #include <linux/sched.h>
32 #include <linux/sched/task_stack.h>
33 #include <linux/slab.h>
34 #include <linux/stacktrace.h>
35 #include <linux/string.h>
36 #include <linux/types.h>
37 #include <linux/vmalloc.h>
38 #include <linux/bug.h>
39
40 #include "kasan.h"
41 #include "../slab.h"
42
43 /*
44 * All functions below always inlined so compiler could
45 * perform better optimizations in each of __asan_loadX/__assn_storeX
46 * depending on memory access size X.
47 */
48
memory_is_poisoned_1(unsigned long addr)49 static __always_inline bool memory_is_poisoned_1(unsigned long addr)
50 {
51 s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
52
53 if (unlikely(shadow_value)) {
54 s8 last_accessible_byte = addr & KASAN_SHADOW_MASK;
55 return unlikely(last_accessible_byte >= shadow_value);
56 }
57
58 return false;
59 }
60
memory_is_poisoned_2_4_8(unsigned long addr,unsigned long size)61 static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
62 unsigned long size)
63 {
64 u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr);
65
66 /*
67 * Access crosses 8(shadow size)-byte boundary. Such access maps
68 * into 2 shadow bytes, so we need to check them both.
69 */
70 if (unlikely(((addr + size - 1) & KASAN_SHADOW_MASK) < size - 1))
71 return *shadow_addr || memory_is_poisoned_1(addr + size - 1);
72
73 return memory_is_poisoned_1(addr + size - 1);
74 }
75
memory_is_poisoned_16(unsigned long addr)76 static __always_inline bool memory_is_poisoned_16(unsigned long addr)
77 {
78 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
79
80 /* Unaligned 16-bytes access maps into 3 shadow bytes. */
81 if (unlikely(!IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE)))
82 return *shadow_addr || memory_is_poisoned_1(addr + 15);
83
84 return *shadow_addr;
85 }
86
bytes_is_nonzero(const u8 * start,size_t size)87 static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
88 size_t size)
89 {
90 while (size) {
91 if (unlikely(*start))
92 return (unsigned long)start;
93 start++;
94 size--;
95 }
96
97 return 0;
98 }
99
memory_is_nonzero(const void * start,const void * end)100 static __always_inline unsigned long memory_is_nonzero(const void *start,
101 const void *end)
102 {
103 unsigned int words;
104 unsigned long ret;
105 unsigned int prefix = (unsigned long)start % 8;
106
107 if (end - start <= 16)
108 return bytes_is_nonzero(start, end - start);
109
110 if (prefix) {
111 prefix = 8 - prefix;
112 ret = bytes_is_nonzero(start, prefix);
113 if (unlikely(ret))
114 return ret;
115 start += prefix;
116 }
117
118 words = (end - start) / 8;
119 while (words) {
120 if (unlikely(*(u64 *)start))
121 return bytes_is_nonzero(start, 8);
122 start += 8;
123 words--;
124 }
125
126 return bytes_is_nonzero(start, (end - start) % 8);
127 }
128
memory_is_poisoned_n(unsigned long addr,size_t size)129 static __always_inline bool memory_is_poisoned_n(unsigned long addr,
130 size_t size)
131 {
132 unsigned long ret;
133
134 ret = memory_is_nonzero(kasan_mem_to_shadow((void *)addr),
135 kasan_mem_to_shadow((void *)addr + size - 1) + 1);
136
137 if (unlikely(ret)) {
138 unsigned long last_byte = addr + size - 1;
139 s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
140
141 if (unlikely(ret != (unsigned long)last_shadow ||
142 ((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow)))
143 return true;
144 }
145 return false;
146 }
147
memory_is_poisoned(unsigned long addr,size_t size)148 static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
149 {
150 if (__builtin_constant_p(size)) {
151 switch (size) {
152 case 1:
153 return memory_is_poisoned_1(addr);
154 case 2:
155 case 4:
156 case 8:
157 return memory_is_poisoned_2_4_8(addr, size);
158 case 16:
159 return memory_is_poisoned_16(addr);
160 default:
161 BUILD_BUG();
162 }
163 }
164
165 return memory_is_poisoned_n(addr, size);
166 }
167
check_memory_region_inline(unsigned long addr,size_t size,bool write,unsigned long ret_ip)168 static __always_inline bool check_memory_region_inline(unsigned long addr,
169 size_t size, bool write,
170 unsigned long ret_ip)
171 {
172 if (unlikely(size == 0))
173 return true;
174
175 if (unlikely((void *)addr <
176 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
177 kasan_report(addr, size, write, ret_ip);
178 return false;
179 }
180
181 if (likely(!memory_is_poisoned(addr, size)))
182 return true;
183
184 kasan_report(addr, size, write, ret_ip);
185 return false;
186 }
187
check_memory_region(unsigned long addr,size_t size,bool write,unsigned long ret_ip)188 bool check_memory_region(unsigned long addr, size_t size, bool write,
189 unsigned long ret_ip)
190 {
191 return check_memory_region_inline(addr, size, write, ret_ip);
192 }
193
kasan_cache_shrink(struct kmem_cache * cache)194 void kasan_cache_shrink(struct kmem_cache *cache)
195 {
196 quarantine_remove_cache(cache);
197 }
198
kasan_cache_shutdown(struct kmem_cache * cache)199 void kasan_cache_shutdown(struct kmem_cache *cache)
200 {
201 if (!__kmem_cache_empty(cache))
202 quarantine_remove_cache(cache);
203 }
204
register_global(struct kasan_global * global)205 static void register_global(struct kasan_global *global)
206 {
207 size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE);
208
209 kasan_unpoison_shadow(global->beg, global->size);
210
211 kasan_poison_shadow(global->beg + aligned_size,
212 global->size_with_redzone - aligned_size,
213 KASAN_GLOBAL_REDZONE);
214 }
215
__asan_register_globals(struct kasan_global * globals,size_t size)216 void __asan_register_globals(struct kasan_global *globals, size_t size)
217 {
218 int i;
219
220 for (i = 0; i < size; i++)
221 register_global(&globals[i]);
222 }
223 EXPORT_SYMBOL(__asan_register_globals);
224
__asan_unregister_globals(struct kasan_global * globals,size_t size)225 void __asan_unregister_globals(struct kasan_global *globals, size_t size)
226 {
227 }
228 EXPORT_SYMBOL(__asan_unregister_globals);
229
230 #define DEFINE_ASAN_LOAD_STORE(size) \
231 void __asan_load##size(unsigned long addr) \
232 { \
233 check_memory_region_inline(addr, size, false, _RET_IP_);\
234 } \
235 EXPORT_SYMBOL(__asan_load##size); \
236 __alias(__asan_load##size) \
237 void __asan_load##size##_noabort(unsigned long); \
238 EXPORT_SYMBOL(__asan_load##size##_noabort); \
239 void __asan_store##size(unsigned long addr) \
240 { \
241 check_memory_region_inline(addr, size, true, _RET_IP_); \
242 } \
243 EXPORT_SYMBOL(__asan_store##size); \
244 __alias(__asan_store##size) \
245 void __asan_store##size##_noabort(unsigned long); \
246 EXPORT_SYMBOL(__asan_store##size##_noabort)
247
248 DEFINE_ASAN_LOAD_STORE(1);
249 DEFINE_ASAN_LOAD_STORE(2);
250 DEFINE_ASAN_LOAD_STORE(4);
251 DEFINE_ASAN_LOAD_STORE(8);
252 DEFINE_ASAN_LOAD_STORE(16);
253
__asan_loadN(unsigned long addr,size_t size)254 void __asan_loadN(unsigned long addr, size_t size)
255 {
256 check_memory_region(addr, size, false, _RET_IP_);
257 }
258 EXPORT_SYMBOL(__asan_loadN);
259
260 __alias(__asan_loadN)
261 void __asan_loadN_noabort(unsigned long, size_t);
262 EXPORT_SYMBOL(__asan_loadN_noabort);
263
__asan_storeN(unsigned long addr,size_t size)264 void __asan_storeN(unsigned long addr, size_t size)
265 {
266 check_memory_region(addr, size, true, _RET_IP_);
267 }
268 EXPORT_SYMBOL(__asan_storeN);
269
270 __alias(__asan_storeN)
271 void __asan_storeN_noabort(unsigned long, size_t);
272 EXPORT_SYMBOL(__asan_storeN_noabort);
273
274 /* to shut up compiler complaints */
__asan_handle_no_return(void)275 void __asan_handle_no_return(void) {}
276 EXPORT_SYMBOL(__asan_handle_no_return);
277
278 /* Emitted by compiler to poison alloca()ed objects. */
__asan_alloca_poison(unsigned long addr,size_t size)279 void __asan_alloca_poison(unsigned long addr, size_t size)
280 {
281 size_t rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE);
282 size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) -
283 rounded_up_size;
284 size_t rounded_down_size = round_down(size, KASAN_SHADOW_SCALE_SIZE);
285
286 const void *left_redzone = (const void *)(addr -
287 KASAN_ALLOCA_REDZONE_SIZE);
288 const void *right_redzone = (const void *)(addr + rounded_up_size);
289
290 WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE));
291
292 kasan_unpoison_shadow((const void *)(addr + rounded_down_size),
293 size - rounded_down_size);
294 kasan_poison_shadow(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
295 KASAN_ALLOCA_LEFT);
296 kasan_poison_shadow(right_redzone,
297 padding_size + KASAN_ALLOCA_REDZONE_SIZE,
298 KASAN_ALLOCA_RIGHT);
299 }
300 EXPORT_SYMBOL(__asan_alloca_poison);
301
302 /* Emitted by compiler to unpoison alloca()ed areas when the stack unwinds. */
__asan_allocas_unpoison(const void * stack_top,const void * stack_bottom)303 void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom)
304 {
305 if (unlikely(!stack_top || stack_top > stack_bottom))
306 return;
307
308 kasan_unpoison_shadow(stack_top, stack_bottom - stack_top);
309 }
310 EXPORT_SYMBOL(__asan_allocas_unpoison);
311
312 /* Emitted by the compiler to [un]poison local variables. */
313 #define DEFINE_ASAN_SET_SHADOW(byte) \
314 void __asan_set_shadow_##byte(const void *addr, size_t size) \
315 { \
316 __memset((void *)addr, 0x##byte, size); \
317 } \
318 EXPORT_SYMBOL(__asan_set_shadow_##byte)
319
320 DEFINE_ASAN_SET_SHADOW(00);
321 DEFINE_ASAN_SET_SHADOW(f1);
322 DEFINE_ASAN_SET_SHADOW(f2);
323 DEFINE_ASAN_SET_SHADOW(f3);
324 DEFINE_ASAN_SET_SHADOW(f5);
325 DEFINE_ASAN_SET_SHADOW(f8);
326