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 12 #include <linux/export.h> 13 #include <linux/interrupt.h> 14 #include <linux/init.h> 15 #include <linux/kasan.h> 16 #include <linux/kernel.h> 17 #include <linux/kfence.h> 18 #include <linux/kmemleak.h> 19 #include <linux/linkage.h> 20 #include <linux/memblock.h> 21 #include <linux/memory.h> 22 #include <linux/mm.h> 23 #include <linux/module.h> 24 #include <linux/printk.h> 25 #include <linux/sched.h> 26 #include <linux/sched/task_stack.h> 27 #include <linux/slab.h> 28 #include <linux/stacktrace.h> 29 #include <linux/string.h> 30 #include <linux/types.h> 31 #include <linux/vmalloc.h> 32 #include <linux/bug.h> 33 34 #include "kasan.h" 35 #include "../slab.h" 36 37 /* 38 * All functions below always inlined so compiler could 39 * perform better optimizations in each of __asan_loadX/__assn_storeX 40 * depending on memory access size X. 41 */ 42 43 static __always_inline bool memory_is_poisoned_1(unsigned long addr) 44 { 45 s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr); 46 47 if (unlikely(shadow_value)) { 48 s8 last_accessible_byte = addr & KASAN_GRANULE_MASK; 49 return unlikely(last_accessible_byte >= shadow_value); 50 } 51 52 return false; 53 } 54 55 static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr, 56 unsigned long size) 57 { 58 u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr); 59 60 /* 61 * Access crosses 8(shadow size)-byte boundary. Such access maps 62 * into 2 shadow bytes, so we need to check them both. 63 */ 64 if (unlikely(((addr + size - 1) & KASAN_GRANULE_MASK) < size - 1)) 65 return *shadow_addr || memory_is_poisoned_1(addr + size - 1); 66 67 return memory_is_poisoned_1(addr + size - 1); 68 } 69 70 static __always_inline bool memory_is_poisoned_16(unsigned long addr) 71 { 72 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr); 73 74 /* Unaligned 16-bytes access maps into 3 shadow bytes. */ 75 if (unlikely(!IS_ALIGNED(addr, KASAN_GRANULE_SIZE))) 76 return *shadow_addr || memory_is_poisoned_1(addr + 15); 77 78 return *shadow_addr; 79 } 80 81 static __always_inline unsigned long bytes_is_nonzero(const u8 *start, 82 size_t size) 83 { 84 while (size) { 85 if (unlikely(*start)) 86 return (unsigned long)start; 87 start++; 88 size--; 89 } 90 91 return 0; 92 } 93 94 static __always_inline unsigned long memory_is_nonzero(const void *start, 95 const void *end) 96 { 97 unsigned int words; 98 unsigned long ret; 99 unsigned int prefix = (unsigned long)start % 8; 100 101 if (end - start <= 16) 102 return bytes_is_nonzero(start, end - start); 103 104 if (prefix) { 105 prefix = 8 - prefix; 106 ret = bytes_is_nonzero(start, prefix); 107 if (unlikely(ret)) 108 return ret; 109 start += prefix; 110 } 111 112 words = (end - start) / 8; 113 while (words) { 114 if (unlikely(*(u64 *)start)) 115 return bytes_is_nonzero(start, 8); 116 start += 8; 117 words--; 118 } 119 120 return bytes_is_nonzero(start, (end - start) % 8); 121 } 122 123 static __always_inline bool memory_is_poisoned_n(unsigned long addr, 124 size_t size) 125 { 126 unsigned long ret; 127 128 ret = memory_is_nonzero(kasan_mem_to_shadow((void *)addr), 129 kasan_mem_to_shadow((void *)addr + size - 1) + 1); 130 131 if (unlikely(ret)) { 132 unsigned long last_byte = addr + size - 1; 133 s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte); 134 135 if (unlikely(ret != (unsigned long)last_shadow || 136 ((long)(last_byte & KASAN_GRANULE_MASK) >= *last_shadow))) 137 return true; 138 } 139 return false; 140 } 141 142 static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size) 143 { 144 if (__builtin_constant_p(size)) { 145 switch (size) { 146 case 1: 147 return memory_is_poisoned_1(addr); 148 case 2: 149 case 4: 150 case 8: 151 return memory_is_poisoned_2_4_8(addr, size); 152 case 16: 153 return memory_is_poisoned_16(addr); 154 default: 155 BUILD_BUG(); 156 } 157 } 158 159 return memory_is_poisoned_n(addr, size); 160 } 161 162 static __always_inline bool check_region_inline(unsigned long addr, 163 size_t size, bool write, 164 unsigned long ret_ip) 165 { 166 if (unlikely(size == 0)) 167 return true; 168 169 if (unlikely(addr + size < addr)) 170 return !kasan_report(addr, size, write, ret_ip); 171 172 if (unlikely((void *)addr < 173 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) { 174 return !kasan_report(addr, size, write, ret_ip); 175 } 176 177 if (likely(!memory_is_poisoned(addr, size))) 178 return true; 179 180 return !kasan_report(addr, size, write, ret_ip); 181 } 182 183 bool kasan_check_range(unsigned long addr, size_t size, bool write, 184 unsigned long ret_ip) 185 { 186 return check_region_inline(addr, size, write, ret_ip); 187 } 188 189 bool kasan_byte_accessible(const void *addr) 190 { 191 s8 shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr)); 192 193 return shadow_byte >= 0 && shadow_byte < KASAN_GRANULE_SIZE; 194 } 195 196 void kasan_cache_shrink(struct kmem_cache *cache) 197 { 198 kasan_quarantine_remove_cache(cache); 199 } 200 201 void kasan_cache_shutdown(struct kmem_cache *cache) 202 { 203 if (!__kmem_cache_empty(cache)) 204 kasan_quarantine_remove_cache(cache); 205 } 206 207 static void register_global(struct kasan_global *global) 208 { 209 size_t aligned_size = round_up(global->size, KASAN_GRANULE_SIZE); 210 211 kasan_unpoison(global->beg, global->size, false); 212 213 kasan_poison(global->beg + aligned_size, 214 global->size_with_redzone - aligned_size, 215 KASAN_GLOBAL_REDZONE, false); 216 } 217 218 void __asan_register_globals(struct kasan_global *globals, size_t size) 219 { 220 int i; 221 222 for (i = 0; i < size; i++) 223 register_global(&globals[i]); 224 } 225 EXPORT_SYMBOL(__asan_register_globals); 226 227 void __asan_unregister_globals(struct kasan_global *globals, size_t size) 228 { 229 } 230 EXPORT_SYMBOL(__asan_unregister_globals); 231 232 #define DEFINE_ASAN_LOAD_STORE(size) \ 233 void __asan_load##size(unsigned long addr) \ 234 { \ 235 check_region_inline(addr, size, false, _RET_IP_); \ 236 } \ 237 EXPORT_SYMBOL(__asan_load##size); \ 238 __alias(__asan_load##size) \ 239 void __asan_load##size##_noabort(unsigned long); \ 240 EXPORT_SYMBOL(__asan_load##size##_noabort); \ 241 void __asan_store##size(unsigned long addr) \ 242 { \ 243 check_region_inline(addr, size, true, _RET_IP_); \ 244 } \ 245 EXPORT_SYMBOL(__asan_store##size); \ 246 __alias(__asan_store##size) \ 247 void __asan_store##size##_noabort(unsigned long); \ 248 EXPORT_SYMBOL(__asan_store##size##_noabort) 249 250 DEFINE_ASAN_LOAD_STORE(1); 251 DEFINE_ASAN_LOAD_STORE(2); 252 DEFINE_ASAN_LOAD_STORE(4); 253 DEFINE_ASAN_LOAD_STORE(8); 254 DEFINE_ASAN_LOAD_STORE(16); 255 256 void __asan_loadN(unsigned long addr, size_t size) 257 { 258 kasan_check_range(addr, size, false, _RET_IP_); 259 } 260 EXPORT_SYMBOL(__asan_loadN); 261 262 __alias(__asan_loadN) 263 void __asan_loadN_noabort(unsigned long, size_t); 264 EXPORT_SYMBOL(__asan_loadN_noabort); 265 266 void __asan_storeN(unsigned long addr, size_t size) 267 { 268 kasan_check_range(addr, size, true, _RET_IP_); 269 } 270 EXPORT_SYMBOL(__asan_storeN); 271 272 __alias(__asan_storeN) 273 void __asan_storeN_noabort(unsigned long, size_t); 274 EXPORT_SYMBOL(__asan_storeN_noabort); 275 276 /* to shut up compiler complaints */ 277 void __asan_handle_no_return(void) {} 278 EXPORT_SYMBOL(__asan_handle_no_return); 279 280 /* Emitted by compiler to poison alloca()ed objects. */ 281 void __asan_alloca_poison(unsigned long addr, size_t size) 282 { 283 size_t rounded_up_size = round_up(size, KASAN_GRANULE_SIZE); 284 size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) - 285 rounded_up_size; 286 size_t rounded_down_size = round_down(size, KASAN_GRANULE_SIZE); 287 288 const void *left_redzone = (const void *)(addr - 289 KASAN_ALLOCA_REDZONE_SIZE); 290 const void *right_redzone = (const void *)(addr + rounded_up_size); 291 292 WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE)); 293 294 kasan_unpoison((const void *)(addr + rounded_down_size), 295 size - rounded_down_size, false); 296 kasan_poison(left_redzone, KASAN_ALLOCA_REDZONE_SIZE, 297 KASAN_ALLOCA_LEFT, false); 298 kasan_poison(right_redzone, padding_size + KASAN_ALLOCA_REDZONE_SIZE, 299 KASAN_ALLOCA_RIGHT, false); 300 } 301 EXPORT_SYMBOL(__asan_alloca_poison); 302 303 /* Emitted by compiler to unpoison alloca()ed areas when the stack unwinds. */ 304 void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom) 305 { 306 if (unlikely(!stack_top || stack_top > stack_bottom)) 307 return; 308 309 kasan_unpoison(stack_top, stack_bottom - stack_top, false); 310 } 311 EXPORT_SYMBOL(__asan_allocas_unpoison); 312 313 /* Emitted by the compiler to [un]poison local variables. */ 314 #define DEFINE_ASAN_SET_SHADOW(byte) \ 315 void __asan_set_shadow_##byte(const void *addr, size_t size) \ 316 { \ 317 __memset((void *)addr, 0x##byte, size); \ 318 } \ 319 EXPORT_SYMBOL(__asan_set_shadow_##byte) 320 321 DEFINE_ASAN_SET_SHADOW(00); 322 DEFINE_ASAN_SET_SHADOW(f1); 323 DEFINE_ASAN_SET_SHADOW(f2); 324 DEFINE_ASAN_SET_SHADOW(f3); 325 DEFINE_ASAN_SET_SHADOW(f5); 326 DEFINE_ASAN_SET_SHADOW(f8); 327 328 void kasan_record_aux_stack(void *addr) 329 { 330 struct page *page = kasan_addr_to_page(addr); 331 struct kmem_cache *cache; 332 struct kasan_alloc_meta *alloc_meta; 333 void *object; 334 335 if (is_kfence_address(addr) || !(page && PageSlab(page))) 336 return; 337 338 cache = page->slab_cache; 339 object = nearest_obj(cache, page, addr); 340 alloc_meta = kasan_get_alloc_meta(cache, object); 341 if (!alloc_meta) 342 return; 343 344 alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0]; 345 alloc_meta->aux_stack[0] = kasan_save_stack(GFP_NOWAIT); 346 } 347 348 void kasan_set_free_info(struct kmem_cache *cache, 349 void *object, u8 tag) 350 { 351 struct kasan_free_meta *free_meta; 352 353 free_meta = kasan_get_free_meta(cache, object); 354 if (!free_meta) 355 return; 356 357 kasan_set_track(&free_meta->free_track, GFP_NOWAIT); 358 /* The object was freed and has free track set. */ 359 *(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREETRACK; 360 } 361 362 struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, 363 void *object, u8 tag) 364 { 365 if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_KMALLOC_FREETRACK) 366 return NULL; 367 /* Free meta must be present with KASAN_KMALLOC_FREETRACK. */ 368 return &kasan_get_free_meta(cache, object)->free_track; 369 } 370