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 (!kasan_arch_is_ready()) 167 return true; 168 169 if (unlikely(size == 0)) 170 return true; 171 172 if (unlikely(addr + size < addr)) 173 return !kasan_report(addr, size, write, ret_ip); 174 175 if (unlikely((void *)addr < 176 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) { 177 return !kasan_report(addr, size, write, ret_ip); 178 } 179 180 if (likely(!memory_is_poisoned(addr, size))) 181 return true; 182 183 return !kasan_report(addr, size, write, ret_ip); 184 } 185 186 bool kasan_check_range(unsigned long addr, size_t size, bool write, 187 unsigned long ret_ip) 188 { 189 return check_region_inline(addr, size, write, ret_ip); 190 } 191 192 bool kasan_byte_accessible(const void *addr) 193 { 194 s8 shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr)); 195 196 return shadow_byte >= 0 && shadow_byte < KASAN_GRANULE_SIZE; 197 } 198 199 void kasan_cache_shrink(struct kmem_cache *cache) 200 { 201 kasan_quarantine_remove_cache(cache); 202 } 203 204 void kasan_cache_shutdown(struct kmem_cache *cache) 205 { 206 if (!__kmem_cache_empty(cache)) 207 kasan_quarantine_remove_cache(cache); 208 } 209 210 static void register_global(struct kasan_global *global) 211 { 212 size_t aligned_size = round_up(global->size, KASAN_GRANULE_SIZE); 213 214 kasan_unpoison(global->beg, global->size, false); 215 216 kasan_poison(global->beg + aligned_size, 217 global->size_with_redzone - aligned_size, 218 KASAN_GLOBAL_REDZONE, false); 219 } 220 221 void __asan_register_globals(struct kasan_global *globals, size_t size) 222 { 223 int i; 224 225 for (i = 0; i < size; i++) 226 register_global(&globals[i]); 227 } 228 EXPORT_SYMBOL(__asan_register_globals); 229 230 void __asan_unregister_globals(struct kasan_global *globals, size_t size) 231 { 232 } 233 EXPORT_SYMBOL(__asan_unregister_globals); 234 235 #define DEFINE_ASAN_LOAD_STORE(size) \ 236 void __asan_load##size(unsigned long addr) \ 237 { \ 238 check_region_inline(addr, size, false, _RET_IP_); \ 239 } \ 240 EXPORT_SYMBOL(__asan_load##size); \ 241 __alias(__asan_load##size) \ 242 void __asan_load##size##_noabort(unsigned long); \ 243 EXPORT_SYMBOL(__asan_load##size##_noabort); \ 244 void __asan_store##size(unsigned long addr) \ 245 { \ 246 check_region_inline(addr, size, true, _RET_IP_); \ 247 } \ 248 EXPORT_SYMBOL(__asan_store##size); \ 249 __alias(__asan_store##size) \ 250 void __asan_store##size##_noabort(unsigned long); \ 251 EXPORT_SYMBOL(__asan_store##size##_noabort) 252 253 DEFINE_ASAN_LOAD_STORE(1); 254 DEFINE_ASAN_LOAD_STORE(2); 255 DEFINE_ASAN_LOAD_STORE(4); 256 DEFINE_ASAN_LOAD_STORE(8); 257 DEFINE_ASAN_LOAD_STORE(16); 258 259 void __asan_loadN(unsigned long addr, size_t size) 260 { 261 kasan_check_range(addr, size, false, _RET_IP_); 262 } 263 EXPORT_SYMBOL(__asan_loadN); 264 265 __alias(__asan_loadN) 266 void __asan_loadN_noabort(unsigned long, size_t); 267 EXPORT_SYMBOL(__asan_loadN_noabort); 268 269 void __asan_storeN(unsigned long addr, size_t size) 270 { 271 kasan_check_range(addr, size, true, _RET_IP_); 272 } 273 EXPORT_SYMBOL(__asan_storeN); 274 275 __alias(__asan_storeN) 276 void __asan_storeN_noabort(unsigned long, size_t); 277 EXPORT_SYMBOL(__asan_storeN_noabort); 278 279 /* to shut up compiler complaints */ 280 void __asan_handle_no_return(void) {} 281 EXPORT_SYMBOL(__asan_handle_no_return); 282 283 /* Emitted by compiler to poison alloca()ed objects. */ 284 void __asan_alloca_poison(unsigned long addr, size_t size) 285 { 286 size_t rounded_up_size = round_up(size, KASAN_GRANULE_SIZE); 287 size_t padding_size = round_up(size, KASAN_ALLOCA_REDZONE_SIZE) - 288 rounded_up_size; 289 size_t rounded_down_size = round_down(size, KASAN_GRANULE_SIZE); 290 291 const void *left_redzone = (const void *)(addr - 292 KASAN_ALLOCA_REDZONE_SIZE); 293 const void *right_redzone = (const void *)(addr + rounded_up_size); 294 295 WARN_ON(!IS_ALIGNED(addr, KASAN_ALLOCA_REDZONE_SIZE)); 296 297 kasan_unpoison((const void *)(addr + rounded_down_size), 298 size - rounded_down_size, false); 299 kasan_poison(left_redzone, KASAN_ALLOCA_REDZONE_SIZE, 300 KASAN_ALLOCA_LEFT, false); 301 kasan_poison(right_redzone, padding_size + KASAN_ALLOCA_REDZONE_SIZE, 302 KASAN_ALLOCA_RIGHT, false); 303 } 304 EXPORT_SYMBOL(__asan_alloca_poison); 305 306 /* Emitted by compiler to unpoison alloca()ed areas when the stack unwinds. */ 307 void __asan_allocas_unpoison(const void *stack_top, const void *stack_bottom) 308 { 309 if (unlikely(!stack_top || stack_top > stack_bottom)) 310 return; 311 312 kasan_unpoison(stack_top, stack_bottom - stack_top, false); 313 } 314 EXPORT_SYMBOL(__asan_allocas_unpoison); 315 316 /* Emitted by the compiler to [un]poison local variables. */ 317 #define DEFINE_ASAN_SET_SHADOW(byte) \ 318 void __asan_set_shadow_##byte(const void *addr, size_t size) \ 319 { \ 320 __memset((void *)addr, 0x##byte, size); \ 321 } \ 322 EXPORT_SYMBOL(__asan_set_shadow_##byte) 323 324 DEFINE_ASAN_SET_SHADOW(00); 325 DEFINE_ASAN_SET_SHADOW(f1); 326 DEFINE_ASAN_SET_SHADOW(f2); 327 DEFINE_ASAN_SET_SHADOW(f3); 328 DEFINE_ASAN_SET_SHADOW(f5); 329 DEFINE_ASAN_SET_SHADOW(f8); 330 331 static void __kasan_record_aux_stack(void *addr, bool can_alloc) 332 { 333 struct slab *slab = kasan_addr_to_slab(addr); 334 struct kmem_cache *cache; 335 struct kasan_alloc_meta *alloc_meta; 336 void *object; 337 338 if (is_kfence_address(addr) || !slab) 339 return; 340 341 cache = slab->slab_cache; 342 object = nearest_obj(cache, slab, addr); 343 alloc_meta = kasan_get_alloc_meta(cache, object); 344 if (!alloc_meta) 345 return; 346 347 alloc_meta->aux_stack[1] = alloc_meta->aux_stack[0]; 348 alloc_meta->aux_stack[0] = kasan_save_stack(GFP_NOWAIT, can_alloc); 349 } 350 351 void kasan_record_aux_stack(void *addr) 352 { 353 return __kasan_record_aux_stack(addr, true); 354 } 355 356 void kasan_record_aux_stack_noalloc(void *addr) 357 { 358 return __kasan_record_aux_stack(addr, false); 359 } 360 361 void kasan_set_free_info(struct kmem_cache *cache, 362 void *object, u8 tag) 363 { 364 struct kasan_free_meta *free_meta; 365 366 free_meta = kasan_get_free_meta(cache, object); 367 if (!free_meta) 368 return; 369 370 kasan_set_track(&free_meta->free_track, GFP_NOWAIT); 371 /* The object was freed and has free track set. */ 372 *(u8 *)kasan_mem_to_shadow(object) = KASAN_SLAB_FREETRACK; 373 } 374 375 struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, 376 void *object, u8 tag) 377 { 378 if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_SLAB_FREETRACK) 379 return NULL; 380 /* Free meta must be present with KASAN_SLAB_FREETRACK. */ 381 return &kasan_get_free_meta(cache, object)->free_track; 382 } 383