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 * This program is free software; you can redistribute it and/or modify 12 * it under the terms of the GNU General Public License version 2 as 13 * published by the Free Software Foundation. 14 * 15 */ 16 17 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 18 19 #include <linux/export.h> 20 #include <linux/interrupt.h> 21 #include <linux/init.h> 22 #include <linux/kasan.h> 23 #include <linux/kernel.h> 24 #include <linux/kmemleak.h> 25 #include <linux/linkage.h> 26 #include <linux/memblock.h> 27 #include <linux/memory.h> 28 #include <linux/mm.h> 29 #include <linux/module.h> 30 #include <linux/printk.h> 31 #include <linux/sched.h> 32 #include <linux/sched/task_stack.h> 33 #include <linux/slab.h> 34 #include <linux/stacktrace.h> 35 #include <linux/string.h> 36 #include <linux/types.h> 37 #include <linux/vmalloc.h> 38 #include <linux/bug.h> 39 40 #include "kasan.h" 41 #include "../slab.h" 42 43 /* 44 * All functions below always inlined so compiler could 45 * perform better optimizations in each of __asan_loadX/__assn_storeX 46 * depending on memory access size X. 47 */ 48 49 static __always_inline bool memory_is_poisoned_1(unsigned long addr) 50 { 51 s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr); 52 53 if (unlikely(shadow_value)) { 54 s8 last_accessible_byte = addr & KASAN_SHADOW_MASK; 55 return unlikely(last_accessible_byte >= shadow_value); 56 } 57 58 return false; 59 } 60 61 static __always_inline bool memory_is_poisoned_2_4_8(unsigned long addr, 62 unsigned long size) 63 { 64 u8 *shadow_addr = (u8 *)kasan_mem_to_shadow((void *)addr); 65 66 /* 67 * Access crosses 8(shadow size)-byte boundary. Such access maps 68 * into 2 shadow bytes, so we need to check them both. 69 */ 70 if (unlikely(((addr + size - 1) & KASAN_SHADOW_MASK) < size - 1)) 71 return *shadow_addr || memory_is_poisoned_1(addr + size - 1); 72 73 return memory_is_poisoned_1(addr + size - 1); 74 } 75 76 static __always_inline bool memory_is_poisoned_16(unsigned long addr) 77 { 78 u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr); 79 80 /* Unaligned 16-bytes access maps into 3 shadow bytes. */ 81 if (unlikely(!IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE))) 82 return *shadow_addr || memory_is_poisoned_1(addr + 15); 83 84 return *shadow_addr; 85 } 86 87 static __always_inline unsigned long bytes_is_nonzero(const u8 *start, 88 size_t size) 89 { 90 while (size) { 91 if (unlikely(*start)) 92 return (unsigned long)start; 93 start++; 94 size--; 95 } 96 97 return 0; 98 } 99 100 static __always_inline unsigned long memory_is_nonzero(const void *start, 101 const void *end) 102 { 103 unsigned int words; 104 unsigned long ret; 105 unsigned int prefix = (unsigned long)start % 8; 106 107 if (end - start <= 16) 108 return bytes_is_nonzero(start, end - start); 109 110 if (prefix) { 111 prefix = 8 - prefix; 112 ret = bytes_is_nonzero(start, prefix); 113 if (unlikely(ret)) 114 return ret; 115 start += prefix; 116 } 117 118 words = (end - start) / 8; 119 while (words) { 120 if (unlikely(*(u64 *)start)) 121 return bytes_is_nonzero(start, 8); 122 start += 8; 123 words--; 124 } 125 126 return bytes_is_nonzero(start, (end - start) % 8); 127 } 128 129 static __always_inline bool memory_is_poisoned_n(unsigned long addr, 130 size_t size) 131 { 132 unsigned long ret; 133 134 ret = memory_is_nonzero(kasan_mem_to_shadow((void *)addr), 135 kasan_mem_to_shadow((void *)addr + size - 1) + 1); 136 137 if (unlikely(ret)) { 138 unsigned long last_byte = addr + size - 1; 139 s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte); 140 141 if (unlikely(ret != (unsigned long)last_shadow || 142 ((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow))) 143 return true; 144 } 145 return false; 146 } 147 148 static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size) 149 { 150 if (__builtin_constant_p(size)) { 151 switch (size) { 152 case 1: 153 return memory_is_poisoned_1(addr); 154 case 2: 155 case 4: 156 case 8: 157 return memory_is_poisoned_2_4_8(addr, size); 158 case 16: 159 return memory_is_poisoned_16(addr); 160 default: 161 BUILD_BUG(); 162 } 163 } 164 165 return memory_is_poisoned_n(addr, size); 166 } 167 168 static __always_inline bool check_memory_region_inline(unsigned long addr, 169 size_t size, bool write, 170 unsigned long ret_ip) 171 { 172 if (unlikely(size == 0)) 173 return true; 174 175 if (unlikely(addr + size < addr)) 176 return !kasan_report(addr, size, write, ret_ip); 177 178 if (unlikely((void *)addr < 179 kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) { 180 return !kasan_report(addr, size, write, ret_ip); 181 } 182 183 if (likely(!memory_is_poisoned(addr, size))) 184 return true; 185 186 return !kasan_report(addr, size, write, ret_ip); 187 } 188 189 bool check_memory_region(unsigned long addr, size_t size, bool write, 190 unsigned long ret_ip) 191 { 192 return check_memory_region_inline(addr, size, write, ret_ip); 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_SHADOW_SCALE_SIZE); 209 210 kasan_unpoison_shadow(global->beg, global->size); 211 212 kasan_poison_shadow(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_SHADOW_SCALE_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_SHADOW_SCALE_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 kasan_unpoison_shadow((const void *)(addr + rounded_down_size), 294 size - rounded_down_size); 295 kasan_poison_shadow(left_redzone, KASAN_ALLOCA_REDZONE_SIZE, 296 KASAN_ALLOCA_LEFT); 297 kasan_poison_shadow(right_redzone, 298 padding_size + KASAN_ALLOCA_REDZONE_SIZE, 299 KASAN_ALLOCA_RIGHT); 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_shadow(stack_top, stack_bottom - stack_top); 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_info; 333 void *object; 334 335 if (!(page && PageSlab(page))) 336 return; 337 338 cache = page->slab_cache; 339 object = nearest_obj(cache, page, addr); 340 alloc_info = get_alloc_info(cache, object); 341 342 /* 343 * record the last two call_rcu() call stacks. 344 */ 345 alloc_info->aux_stack[1] = alloc_info->aux_stack[0]; 346 alloc_info->aux_stack[0] = kasan_save_stack(GFP_NOWAIT); 347 } 348 349 void kasan_set_free_info(struct kmem_cache *cache, 350 void *object, u8 tag) 351 { 352 struct kasan_free_meta *free_meta; 353 354 free_meta = get_free_info(cache, object); 355 kasan_set_track(&free_meta->free_track, GFP_NOWAIT); 356 357 /* 358 * the object was freed and has free track set 359 */ 360 *(u8 *)kasan_mem_to_shadow(object) = KASAN_KMALLOC_FREETRACK; 361 } 362 363 struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, 364 void *object, u8 tag) 365 { 366 if (*(u8 *)kasan_mem_to_shadow(object) != KASAN_KMALLOC_FREETRACK) 367 return NULL; 368 return &get_free_info(cache, object)->free_track; 369 } 370