generic.c 9.6 KB

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  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. #include <linux/export.h>
  12. #include <linux/interrupt.h>
  13. #include <linux/init.h>
  14. #include <linux/kasan.h>
  15. #include <linux/kernel.h>
  16. #include <linux/kfence.h>
  17. #include <linux/kmemleak.h>
  18. #include <linux/linkage.h>
  19. #include <linux/memblock.h>
  20. #include <linux/memory.h>
  21. #include <linux/mm.h>
  22. #include <linux/module.h>
  23. #include <linux/printk.h>
  24. #include <linux/sched.h>
  25. #include <linux/sched/task_stack.h>
  26. #include <linux/slab.h>
  27. #include <linux/stacktrace.h>
  28. #include <linux/string.h>
  29. #include <linux/types.h>
  30. #include <linux/vmalloc.h>
  31. #include <linux/bug.h>
  32. #include "kasan.h"
  33. #include "../slab.h"
  34. /*
  35. * All functions below always inlined so compiler could
  36. * perform better optimizations in each of __asan_loadX/__assn_storeX
  37. * depending on memory access size X.
  38. */
  39. static __always_inline bool memory_is_poisoned_1(unsigned long addr)
  40. {
  41. s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr);
  42. if (unlikely(shadow_value)) {
  43. s8 last_accessible_byte = addr & KASAN_GRANULE_MASK;
  44. return unlikely(last_accessible_byte >= shadow_value);
  45. }
  46. return false;
  47. }
  48. static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr,
  49. unsigned long size)
  50. {
  51. u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr);
  52. /*
  53. * Access crosses 8(shadow size)-byte boundary. Such access maps
  54. * into 2 shadow bytes, so we need to check them both.
  55. */
  56. if (unlikely(((addr + size - 1) & KASAN_GRANULE_MASK) < size - 1))
  57. return *shadow_addr || memory_is_poisoned_1(addr + size - 1);
  58. return memory_is_poisoned_1(addr + size - 1);
  59. }
  60. static __always_inline bool memory_is_poisoned_16(unsigned long addr)
  61. {
  62. u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr);
  63. /* Unaligned 16-bytes access maps into 3 shadow bytes. */
  64. if (unlikely(!IS_ALIGNED(addr, KASAN_GRANULE_SIZE)))
  65. return *shadow_addr || memory_is_poisoned_1(addr + 15);
  66. return *shadow_addr;
  67. }
  68. static __always_inline unsigned long bytes_is_nonzero(const u8 *start,
  69. size_t size)
  70. {
  71. while (size) {
  72. if (unlikely(*start))
  73. return (unsigned long)start;
  74. start++;
  75. size--;
  76. }
  77. return 0;
  78. }
  79. static __always_inline unsigned long memory_is_nonzero(const void *start,
  80. const void *end)
  81. {
  82. unsigned int words;
  83. unsigned long ret;
  84. unsigned int prefix = (unsigned long)start % 8;
  85. if (end - start <= 16)
  86. return bytes_is_nonzero(start, end - start);
  87. if (prefix) {
  88. prefix = 8 - prefix;
  89. ret = bytes_is_nonzero(start, prefix);
  90. if (unlikely(ret))
  91. return ret;
  92. start += prefix;
  93. }
  94. words = (end - start) / 8;
  95. while (words) {
  96. if (unlikely(*(u64 *)start))
  97. return bytes_is_nonzero(start, 8);
  98. start += 8;
  99. words--;
  100. }
  101. return bytes_is_nonzero(start, (end - start) % 8);
  102. }
  103. static __always_inline bool memory_is_poisoned_n(unsigned long addr,
  104. size_t size)
  105. {
  106. unsigned long ret;
  107. ret = memory_is_nonzero(kasan_mem_to_shadow((void *)addr),
  108. kasan_mem_to_shadow((void *)addr + size - 1) + 1);
  109. if (unlikely(ret)) {
  110. unsigned long last_byte = addr + size - 1;
  111. s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte);
  112. if (unlikely(ret != (unsigned long)last_shadow ||
  113. ((long)(last_byte & KASAN_GRANULE_MASK) >= *last_shadow)))
  114. return true;
  115. }
  116. return false;
  117. }
  118. static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size)
  119. {
  120. if (__builtin_constant_p(size)) {
  121. switch (size) {
  122. case 1:
  123. return memory_is_poisoned_1(addr);
  124. case 2:
  125. case 4:
  126. case 8:
  127. return memory_is_poisoned_2_4_8(addr, size);
  128. case 16:
  129. return memory_is_poisoned_16(addr);
  130. default:
  131. BUILD_BUG();
  132. }
  133. }
  134. return memory_is_poisoned_n(addr, size);
  135. }
  136. static __always_inline bool check_region_inline(unsigned long addr,
  137. size_t size, bool write,
  138. unsigned long ret_ip)
  139. {
  140. if (unlikely(size == 0))
  141. return true;
  142. if (unlikely(addr + size < addr))
  143. return !kasan_report(addr, size, write, ret_ip);
  144. if (unlikely((void *)addr <
  145. kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) {
  146. return !kasan_report(addr, size, write, ret_ip);
  147. }
  148. if (likely(!memory_is_poisoned(addr, size)))
  149. return true;
  150. return !kasan_report(addr, size, write, ret_ip);
  151. }
  152. bool kasan_check_range(unsigned long addr, size_t size, bool write,
  153. unsigned long ret_ip)
  154. {
  155. return check_region_inline(addr, size, write, ret_ip);
  156. }
  157. bool kasan_byte_accessible(const void *addr)
  158. {
  159. s8 shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr));
  160. return shadow_byte >= 0 && shadow_byte < KASAN_GRANULE_SIZE;
  161. }
  162. void kasan_cache_shrink(struct kmem_cache *cache)
  163. {
  164. kasan_quarantine_remove_cache(cache);
  165. }
  166. void kasan_cache_shutdown(struct kmem_cache *cache)
  167. {
  168. if (!__kmem_cache_empty(cache))
  169. kasan_quarantine_remove_cache(cache);
  170. }
  171. static void register_global(struct kasan_global *global)
  172. {
  173. size_t aligned_size = round_up(global->size, KASAN_GRANULE_SIZE);
  174. kasan_unpoison(global->beg, global->size, false);
  175. kasan_poison(global->beg + aligned_size,
  176. global->size_with_redzone - aligned_size,
  177. KASAN_GLOBAL_REDZONE, false);
  178. }
  179. void __asan_register_globals(struct kasan_global *globals, size_t size)
  180. {
  181. int i;
  182. for (i = 0; i < size; i++)
  183. register_global(&globals[i]);
  184. }
  185. EXPORT_SYMBOL(__asan_register_globals);
  186. void __asan_unregister_globals(struct kasan_global *globals, size_t size)
  187. {
  188. }
  189. EXPORT_SYMBOL(__asan_unregister_globals);
  190. #define DEFINE_ASAN_LOAD_STORE(size) \
  191. void __asan_load##size(unsigned long addr) \
  192. { \
  193. check_region_inline(addr, size, false, _RET_IP_); \
  194. } \
  195. EXPORT_SYMBOL(__asan_load##size); \
  196. __alias(__asan_load##size) \
  197. void __asan_load##size##_noabort(unsigned long); \
  198. EXPORT_SYMBOL(__asan_load##size##_noabort); \
  199. void __asan_store##size(unsigned long addr) \
  200. { \
  201. check_region_inline(addr, size, true, _RET_IP_); \
  202. } \
  203. EXPORT_SYMBOL(__asan_store##size); \
  204. __alias(__asan_store##size) \
  205. void __asan_store##size##_noabort(unsigned long); \
  206. EXPORT_SYMBOL(__asan_store##size##_noabort)
  207. DEFINE_ASAN_LOAD_STORE(1);
  208. DEFINE_ASAN_LOAD_STORE(2);
  209. DEFINE_ASAN_LOAD_STORE(4);
  210. DEFINE_ASAN_LOAD_STORE(8);
  211. DEFINE_ASAN_LOAD_STORE(16);
  212. void __asan_loadN(unsigned long addr, size_t size)
  213. {
  214. kasan_check_range(addr, size, false, _RET_IP_);
  215. }
  216. EXPORT_SYMBOL(__asan_loadN);
  217. __alias(__asan_loadN)
  218. void __asan_loadN_noabort(unsigned long, size_t);
  219. EXPORT_SYMBOL(__asan_loadN_noabort);
  220. void __asan_storeN(unsigned long addr, size_t size)
  221. {
  222. kasan_check_range(addr, size, true, _RET_IP_);
  223. }
  224. EXPORT_SYMBOL(__asan_storeN);
  225. __alias(__asan_storeN)
  226. void __asan_storeN_noabort(unsigned long, size_t);
  227. EXPORT_SYMBOL(__asan_storeN_noabort);
  228. /* to shut up compiler complaints */
  229. void __asan_handle_no_return(void) {}
  230. EXPORT_SYMBOL(__asan_handle_no_return);
  231. /* Emitted by compiler to poison alloca()ed objects. */
  232. void __asan_alloca_poison(unsigned long addr, size_t size)
  233. {
  234. size_t rounded_up_size = round_up(size, KASAN_GRANULE_SIZE);
  235. size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) -
  236. rounded_up_size;
  237. size_t rounded_down_size = round_down(size, KASAN_GRANULE_SIZE);
  238. const void *left_redzone = (const void *)(addr -
  239. KASAN_ALLOCA_REDZONE_SIZE);
  240. const void *right_redzone = (const void *)(addr + rounded_up_size);
  241. WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE));
  242. kasan_unpoison((const void *)(addr + rounded_down_size),
  243. size - rounded_down_size, false);
  244. kasan_poison(left_redzone, KASAN_ALLOCA_REDZONE_SIZE,
  245. KASAN_ALLOCA_LEFT, false);
  246. kasan_poison(right_redzone, padding_size + KASAN_ALLOCA_REDZONE_SIZE,
  247. KASAN_ALLOCA_RIGHT, false);
  248. }
  249. EXPORT_SYMBOL(__asan_alloca_poison);
  250. /* Emitted by compiler to unpoison alloca()ed areas when the stack unwinds. */
  251. void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom)
  252. {
  253. if (unlikely(!stack_top || stack_top > stack_bottom))
  254. return;
  255. kasan_unpoison(stack_top, stack_bottom - stack_top, false);
  256. }
  257. EXPORT_SYMBOL(__asan_allocas_unpoison);
  258. /* Emitted by the compiler to [un]poison local variables. */
  259. #define DEFINE_ASAN_SET_SHADOW(byte) \
  260. void __asan_set_shadow_##byte(const void *addr, size_t size) \
  261. { \
  262. __memset((void *)addr, 0x##byte, size); \
  263. } \
  264. EXPORT_SYMBOL(__asan_set_shadow_##byte)
  265. DEFINE_ASAN_SET_SHADOW(00);
  266. DEFINE_ASAN_SET_SHADOW(f1);
  267. DEFINE_ASAN_SET_SHADOW(f2);
  268. DEFINE_ASAN_SET_SHADOW(f3);
  269. DEFINE_ASAN_SET_SHADOW(f5);
  270. DEFINE_ASAN_SET_SHADOW(f8);
  271. void kasan_record_aux_stack(void *addr)
  272. {
  273. struct page *page = kasan_addr_to_page(addr);
  274. struct kmem_cache *cache;
  275. struct kasan_alloc_meta *alloc_meta;
  276. void *object;
  277. if (is_kfence_address(addr) || !(page && PageSlab(page)))
  278. return;
  279. cache = page->slab_cache;
  280. object = nearest_obj(cache, page, addr);
  281. alloc_meta = kasan_get_alloc_meta(cache, object);
  282. if (!alloc_meta)
  283. return;
  284. alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0];
  285. alloc_meta->aux_stack[0] = kasan_save_stack(GFP_NOWAIT);
  286. }
  287. void kasan_set_free_info(struct kmem_cache *cache,
  288. void *object, u8 tag)
  289. {
  290. struct kasan_free_meta *free_meta;
  291. free_meta = kasan_get_free_meta(cache, object);
  292. if (!free_meta)
  293. return;
  294. kasan_set_track(&free_meta->free_track, GFP_NOWAIT);
  295. /* The object was freed and has free track set. */
  296. *(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREETRACK;
  297. }
  298. struct kasan_track *kasan_get_free_track(struct kmem_cache *cache,
  299. void *object, u8 tag)
  300. {
  301. if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_KMALLOC_FREETRACK)
  302. return NULL;
  303. /* Free meta must be present with KASAN_KMALLOC_FREETRACK. */
  304. return &kasan_get_free_meta(cache, object)->free_track;
  305. }