mm/kasan/generic.c

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