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0b24becc AR |
1 | /* |
2 | * This file contains shadow memory manipulation code. | |
3 | * | |
4 | * Copyright (c) 2014 Samsung Electronics Co., Ltd. | |
5 | * Author: Andrey Ryabinin <a.ryabinin@samsung.com> | |
6 | * | |
7 | * Some of code borrowed from https://github.com/xairy/linux by | |
8 | * Andrey Konovalov <adech.fo@gmail.com> | |
9 | * | |
10 | * This program is free software; you can redistribute it and/or modify | |
11 | * it under the terms of the GNU General Public License version 2 as | |
12 | * published by the Free Software Foundation. | |
13 | * | |
14 | */ | |
15 | ||
16 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
17 | #define DISABLE_BRANCH_PROFILING | |
18 | ||
19 | #include <linux/export.h> | |
20 | #include <linux/init.h> | |
21 | #include <linux/kernel.h> | |
22 | #include <linux/memblock.h> | |
786a8959 | 23 | #include <linux/memory.h> |
0b24becc AR |
24 | #include <linux/mm.h> |
25 | #include <linux/printk.h> | |
26 | #include <linux/sched.h> | |
27 | #include <linux/slab.h> | |
28 | #include <linux/stacktrace.h> | |
29 | #include <linux/string.h> | |
30 | #include <linux/types.h> | |
31 | #include <linux/kasan.h> | |
32 | ||
33 | #include "kasan.h" | |
0316bec2 | 34 | #include "../slab.h" |
0b24becc AR |
35 | |
36 | /* | |
37 | * Poisons the shadow memory for 'size' bytes starting from 'addr'. | |
38 | * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE. | |
39 | */ | |
40 | static void kasan_poison_shadow(const void *address, size_t size, u8 value) | |
41 | { | |
42 | void *shadow_start, *shadow_end; | |
43 | ||
44 | shadow_start = kasan_mem_to_shadow(address); | |
45 | shadow_end = kasan_mem_to_shadow(address + size); | |
46 | ||
47 | memset(shadow_start, value, shadow_end - shadow_start); | |
48 | } | |
49 | ||
50 | void kasan_unpoison_shadow(const void *address, size_t size) | |
51 | { | |
52 | kasan_poison_shadow(address, size, 0); | |
53 | ||
54 | if (size & KASAN_SHADOW_MASK) { | |
55 | u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size); | |
56 | *shadow = size & KASAN_SHADOW_MASK; | |
57 | } | |
58 | } | |
59 | ||
60 | ||
61 | /* | |
62 | * All functions below always inlined so compiler could | |
63 | * perform better optimizations in each of __asan_loadX/__assn_storeX | |
64 | * depending on memory access size X. | |
65 | */ | |
66 | ||
67 | static __always_inline bool memory_is_poisoned_1(unsigned long addr) | |
68 | { | |
69 | s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr); | |
70 | ||
71 | if (unlikely(shadow_value)) { | |
72 | s8 last_accessible_byte = addr & KASAN_SHADOW_MASK; | |
73 | return unlikely(last_accessible_byte >= shadow_value); | |
74 | } | |
75 | ||
76 | return false; | |
77 | } | |
78 | ||
79 | static __always_inline bool memory_is_poisoned_2(unsigned long addr) | |
80 | { | |
81 | u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr); | |
82 | ||
83 | if (unlikely(*shadow_addr)) { | |
84 | if (memory_is_poisoned_1(addr + 1)) | |
85 | return true; | |
86 | ||
87 | if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0)) | |
88 | return false; | |
89 | ||
90 | return unlikely(*(u8 *)shadow_addr); | |
91 | } | |
92 | ||
93 | return false; | |
94 | } | |
95 | ||
96 | static __always_inline bool memory_is_poisoned_4(unsigned long addr) | |
97 | { | |
98 | u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr); | |
99 | ||
100 | if (unlikely(*shadow_addr)) { | |
101 | if (memory_is_poisoned_1(addr + 3)) | |
102 | return true; | |
103 | ||
104 | if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3)) | |
105 | return false; | |
106 | ||
107 | return unlikely(*(u8 *)shadow_addr); | |
108 | } | |
109 | ||
110 | return false; | |
111 | } | |
112 | ||
113 | static __always_inline bool memory_is_poisoned_8(unsigned long addr) | |
114 | { | |
115 | u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr); | |
116 | ||
117 | if (unlikely(*shadow_addr)) { | |
118 | if (memory_is_poisoned_1(addr + 7)) | |
119 | return true; | |
120 | ||
121 | if (likely(((addr + 7) & KASAN_SHADOW_MASK) >= 7)) | |
122 | return false; | |
123 | ||
124 | return unlikely(*(u8 *)shadow_addr); | |
125 | } | |
126 | ||
127 | return false; | |
128 | } | |
129 | ||
130 | static __always_inline bool memory_is_poisoned_16(unsigned long addr) | |
131 | { | |
132 | u32 *shadow_addr = (u32 *)kasan_mem_to_shadow((void *)addr); | |
133 | ||
134 | if (unlikely(*shadow_addr)) { | |
135 | u16 shadow_first_bytes = *(u16 *)shadow_addr; | |
136 | s8 last_byte = (addr + 15) & KASAN_SHADOW_MASK; | |
137 | ||
138 | if (unlikely(shadow_first_bytes)) | |
139 | return true; | |
140 | ||
141 | if (likely(!last_byte)) | |
142 | return false; | |
143 | ||
144 | return memory_is_poisoned_1(addr + 15); | |
145 | } | |
146 | ||
147 | return false; | |
148 | } | |
149 | ||
150 | static __always_inline unsigned long bytes_is_zero(const u8 *start, | |
151 | size_t size) | |
152 | { | |
153 | while (size) { | |
154 | if (unlikely(*start)) | |
155 | return (unsigned long)start; | |
156 | start++; | |
157 | size--; | |
158 | } | |
159 | ||
160 | return 0; | |
161 | } | |
162 | ||
163 | static __always_inline unsigned long memory_is_zero(const void *start, | |
164 | const void *end) | |
165 | { | |
166 | unsigned int words; | |
167 | unsigned long ret; | |
168 | unsigned int prefix = (unsigned long)start % 8; | |
169 | ||
170 | if (end - start <= 16) | |
171 | return bytes_is_zero(start, end - start); | |
172 | ||
173 | if (prefix) { | |
174 | prefix = 8 - prefix; | |
175 | ret = bytes_is_zero(start, prefix); | |
176 | if (unlikely(ret)) | |
177 | return ret; | |
178 | start += prefix; | |
179 | } | |
180 | ||
181 | words = (end - start) / 8; | |
182 | while (words) { | |
183 | if (unlikely(*(u64 *)start)) | |
184 | return bytes_is_zero(start, 8); | |
185 | start += 8; | |
186 | words--; | |
187 | } | |
188 | ||
189 | return bytes_is_zero(start, (end - start) % 8); | |
190 | } | |
191 | ||
192 | static __always_inline bool memory_is_poisoned_n(unsigned long addr, | |
193 | size_t size) | |
194 | { | |
195 | unsigned long ret; | |
196 | ||
197 | ret = memory_is_zero(kasan_mem_to_shadow((void *)addr), | |
198 | kasan_mem_to_shadow((void *)addr + size - 1) + 1); | |
199 | ||
200 | if (unlikely(ret)) { | |
201 | unsigned long last_byte = addr + size - 1; | |
202 | s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte); | |
203 | ||
204 | if (unlikely(ret != (unsigned long)last_shadow || | |
205 | ((last_byte & KASAN_SHADOW_MASK) >= *last_shadow))) | |
206 | return true; | |
207 | } | |
208 | return false; | |
209 | } | |
210 | ||
211 | static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size) | |
212 | { | |
213 | if (__builtin_constant_p(size)) { | |
214 | switch (size) { | |
215 | case 1: | |
216 | return memory_is_poisoned_1(addr); | |
217 | case 2: | |
218 | return memory_is_poisoned_2(addr); | |
219 | case 4: | |
220 | return memory_is_poisoned_4(addr); | |
221 | case 8: | |
222 | return memory_is_poisoned_8(addr); | |
223 | case 16: | |
224 | return memory_is_poisoned_16(addr); | |
225 | default: | |
226 | BUILD_BUG(); | |
227 | } | |
228 | } | |
229 | ||
230 | return memory_is_poisoned_n(addr, size); | |
231 | } | |
232 | ||
233 | ||
234 | static __always_inline void check_memory_region(unsigned long addr, | |
235 | size_t size, bool write) | |
236 | { | |
237 | struct kasan_access_info info; | |
238 | ||
239 | if (unlikely(size == 0)) | |
240 | return; | |
241 | ||
242 | if (unlikely((void *)addr < | |
243 | kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) { | |
244 | info.access_addr = (void *)addr; | |
245 | info.access_size = size; | |
246 | info.is_write = write; | |
247 | info.ip = _RET_IP_; | |
248 | kasan_report_user_access(&info); | |
249 | return; | |
250 | } | |
251 | ||
252 | if (likely(!memory_is_poisoned(addr, size))) | |
253 | return; | |
254 | ||
255 | kasan_report(addr, size, write, _RET_IP_); | |
256 | } | |
257 | ||
b8c73fc2 AR |
258 | void kasan_alloc_pages(struct page *page, unsigned int order) |
259 | { | |
260 | if (likely(!PageHighMem(page))) | |
261 | kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order); | |
262 | } | |
263 | ||
264 | void kasan_free_pages(struct page *page, unsigned int order) | |
265 | { | |
266 | if (likely(!PageHighMem(page))) | |
267 | kasan_poison_shadow(page_address(page), | |
268 | PAGE_SIZE << order, | |
269 | KASAN_FREE_PAGE); | |
270 | } | |
271 | ||
0316bec2 AR |
272 | void kasan_poison_slab(struct page *page) |
273 | { | |
274 | kasan_poison_shadow(page_address(page), | |
275 | PAGE_SIZE << compound_order(page), | |
276 | KASAN_KMALLOC_REDZONE); | |
277 | } | |
278 | ||
279 | void kasan_unpoison_object_data(struct kmem_cache *cache, void *object) | |
280 | { | |
281 | kasan_unpoison_shadow(object, cache->object_size); | |
282 | } | |
283 | ||
284 | void kasan_poison_object_data(struct kmem_cache *cache, void *object) | |
285 | { | |
286 | kasan_poison_shadow(object, | |
287 | round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE), | |
288 | KASAN_KMALLOC_REDZONE); | |
289 | } | |
290 | ||
291 | void kasan_slab_alloc(struct kmem_cache *cache, void *object) | |
292 | { | |
293 | kasan_kmalloc(cache, object, cache->object_size); | |
294 | } | |
295 | ||
296 | void kasan_slab_free(struct kmem_cache *cache, void *object) | |
297 | { | |
298 | unsigned long size = cache->object_size; | |
299 | unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE); | |
300 | ||
301 | /* RCU slabs could be legally used after free within the RCU period */ | |
302 | if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU)) | |
303 | return; | |
304 | ||
305 | kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE); | |
306 | } | |
307 | ||
308 | void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size) | |
309 | { | |
310 | unsigned long redzone_start; | |
311 | unsigned long redzone_end; | |
312 | ||
313 | if (unlikely(object == NULL)) | |
314 | return; | |
315 | ||
316 | redzone_start = round_up((unsigned long)(object + size), | |
317 | KASAN_SHADOW_SCALE_SIZE); | |
318 | redzone_end = round_up((unsigned long)object + cache->object_size, | |
319 | KASAN_SHADOW_SCALE_SIZE); | |
320 | ||
321 | kasan_unpoison_shadow(object, size); | |
322 | kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start, | |
323 | KASAN_KMALLOC_REDZONE); | |
324 | } | |
325 | EXPORT_SYMBOL(kasan_kmalloc); | |
326 | ||
327 | void kasan_kmalloc_large(const void *ptr, size_t size) | |
328 | { | |
329 | struct page *page; | |
330 | unsigned long redzone_start; | |
331 | unsigned long redzone_end; | |
332 | ||
333 | if (unlikely(ptr == NULL)) | |
334 | return; | |
335 | ||
336 | page = virt_to_page(ptr); | |
337 | redzone_start = round_up((unsigned long)(ptr + size), | |
338 | KASAN_SHADOW_SCALE_SIZE); | |
339 | redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page)); | |
340 | ||
341 | kasan_unpoison_shadow(ptr, size); | |
342 | kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start, | |
343 | KASAN_PAGE_REDZONE); | |
344 | } | |
345 | ||
346 | void kasan_krealloc(const void *object, size_t size) | |
347 | { | |
348 | struct page *page; | |
349 | ||
350 | if (unlikely(object == ZERO_SIZE_PTR)) | |
351 | return; | |
352 | ||
353 | page = virt_to_head_page(object); | |
354 | ||
355 | if (unlikely(!PageSlab(page))) | |
356 | kasan_kmalloc_large(object, size); | |
357 | else | |
358 | kasan_kmalloc(page->slab_cache, object, size); | |
359 | } | |
360 | ||
361 | void kasan_kfree_large(const void *ptr) | |
362 | { | |
363 | struct page *page = virt_to_page(ptr); | |
364 | ||
365 | kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page), | |
366 | KASAN_FREE_PAGE); | |
367 | } | |
368 | ||
0b24becc AR |
369 | #define DEFINE_ASAN_LOAD_STORE(size) \ |
370 | void __asan_load##size(unsigned long addr) \ | |
371 | { \ | |
372 | check_memory_region(addr, size, false); \ | |
373 | } \ | |
374 | EXPORT_SYMBOL(__asan_load##size); \ | |
375 | __alias(__asan_load##size) \ | |
376 | void __asan_load##size##_noabort(unsigned long); \ | |
377 | EXPORT_SYMBOL(__asan_load##size##_noabort); \ | |
378 | void __asan_store##size(unsigned long addr) \ | |
379 | { \ | |
380 | check_memory_region(addr, size, true); \ | |
381 | } \ | |
382 | EXPORT_SYMBOL(__asan_store##size); \ | |
383 | __alias(__asan_store##size) \ | |
384 | void __asan_store##size##_noabort(unsigned long); \ | |
385 | EXPORT_SYMBOL(__asan_store##size##_noabort) | |
386 | ||
387 | DEFINE_ASAN_LOAD_STORE(1); | |
388 | DEFINE_ASAN_LOAD_STORE(2); | |
389 | DEFINE_ASAN_LOAD_STORE(4); | |
390 | DEFINE_ASAN_LOAD_STORE(8); | |
391 | DEFINE_ASAN_LOAD_STORE(16); | |
392 | ||
393 | void __asan_loadN(unsigned long addr, size_t size) | |
394 | { | |
395 | check_memory_region(addr, size, false); | |
396 | } | |
397 | EXPORT_SYMBOL(__asan_loadN); | |
398 | ||
399 | __alias(__asan_loadN) | |
400 | void __asan_loadN_noabort(unsigned long, size_t); | |
401 | EXPORT_SYMBOL(__asan_loadN_noabort); | |
402 | ||
403 | void __asan_storeN(unsigned long addr, size_t size) | |
404 | { | |
405 | check_memory_region(addr, size, true); | |
406 | } | |
407 | EXPORT_SYMBOL(__asan_storeN); | |
408 | ||
409 | __alias(__asan_storeN) | |
410 | void __asan_storeN_noabort(unsigned long, size_t); | |
411 | EXPORT_SYMBOL(__asan_storeN_noabort); | |
412 | ||
413 | /* to shut up compiler complaints */ | |
414 | void __asan_handle_no_return(void) {} | |
415 | EXPORT_SYMBOL(__asan_handle_no_return); | |
786a8959 AR |
416 | |
417 | #ifdef CONFIG_MEMORY_HOTPLUG | |
418 | static int kasan_mem_notifier(struct notifier_block *nb, | |
419 | unsigned long action, void *data) | |
420 | { | |
421 | return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK; | |
422 | } | |
423 | ||
424 | static int __init kasan_memhotplug_init(void) | |
425 | { | |
426 | pr_err("WARNING: KASan doesn't support memory hot-add\n"); | |
427 | pr_err("Memory hot-add will be disabled\n"); | |
428 | ||
429 | hotplug_memory_notifier(kasan_mem_notifier, 0); | |
430 | ||
431 | return 0; | |
432 | } | |
433 | ||
434 | module_init(kasan_memhotplug_init); | |
435 | #endif |