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