1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * This file contains KASAN shadow initialization code. 4 * 5 * Copyright (c) 2015 Samsung Electronics Co., Ltd. 6 * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> 7 */ 8 9 #include <linux/memblock.h> 10 #include <linux/init.h> 11 #include <linux/kasan.h> 12 #include <linux/kernel.h> 13 #include <linux/mm.h> 14 #include <linux/pfn.h> 15 #include <linux/slab.h> 16 17 #include <asm/page.h> 18 #include <asm/pgalloc.h> 19 20 #include "kasan.h" 21 22 /* 23 * This page serves two purposes: 24 * - It used as early shadow memory. The entire shadow region populated 25 * with this page, before we will be able to setup normal shadow memory. 26 * - Latter it reused it as zero shadow to cover large ranges of memory 27 * that allowed to access, but not handled by kasan (vmalloc/vmemmap ...). 28 */ 29 unsigned char kasan_early_shadow_page[PAGE_SIZE] __page_aligned_bss; 30 31 #if CONFIG_PGTABLE_LEVELS > 4 32 p4d_t kasan_early_shadow_p4d[MAX_PTRS_PER_P4D] __page_aligned_bss; 33 static inline bool kasan_p4d_table(pgd_t pgd) 34 { 35 return pgd_page(pgd) == virt_to_page(lm_alias(kasan_early_shadow_p4d)); 36 } 37 #else 38 static inline bool kasan_p4d_table(pgd_t pgd) 39 { 40 return false; 41 } 42 #endif 43 #if CONFIG_PGTABLE_LEVELS > 3 44 pud_t kasan_early_shadow_pud[MAX_PTRS_PER_PUD] __page_aligned_bss; 45 static inline bool kasan_pud_table(p4d_t p4d) 46 { 47 return p4d_page(p4d) == virt_to_page(lm_alias(kasan_early_shadow_pud)); 48 } 49 #else 50 static inline bool kasan_pud_table(p4d_t p4d) 51 { 52 return false; 53 } 54 #endif 55 #if CONFIG_PGTABLE_LEVELS > 2 56 pmd_t kasan_early_shadow_pmd[MAX_PTRS_PER_PMD] __page_aligned_bss; 57 static inline bool kasan_pmd_table(pud_t pud) 58 { 59 return pud_page(pud) == virt_to_page(lm_alias(kasan_early_shadow_pmd)); 60 } 61 #else 62 static inline bool kasan_pmd_table(pud_t pud) 63 { 64 return false; 65 } 66 #endif 67 pte_t kasan_early_shadow_pte[MAX_PTRS_PER_PTE + PTE_HWTABLE_PTRS] 68 __page_aligned_bss; 69 70 static inline bool kasan_pte_table(pmd_t pmd) 71 { 72 return pmd_page(pmd) == virt_to_page(lm_alias(kasan_early_shadow_pte)); 73 } 74 75 static inline bool kasan_early_shadow_page_entry(pte_t pte) 76 { 77 return pte_page(pte) == virt_to_page(lm_alias(kasan_early_shadow_page)); 78 } 79 80 static __init void *early_alloc(size_t size, int node) 81 { 82 void *ptr = memblock_alloc_try_nid(size, size, __pa(MAX_DMA_ADDRESS), 83 MEMBLOCK_ALLOC_ACCESSIBLE, node); 84 85 if (!ptr) 86 panic("%s: Failed to allocate %zu bytes align=%zx nid=%d from=%llx\n", 87 __func__, size, size, node, (u64)__pa(MAX_DMA_ADDRESS)); 88 89 return ptr; 90 } 91 92 static void __ref zero_pte_populate(pmd_t *pmd, unsigned long addr, 93 unsigned long end) 94 { 95 pte_t *pte = pte_offset_kernel(pmd, addr); 96 pte_t zero_pte; 97 98 zero_pte = pfn_pte(PFN_DOWN(__pa_symbol(kasan_early_shadow_page)), 99 PAGE_KERNEL); 100 zero_pte = pte_wrprotect(zero_pte); 101 102 while (addr + PAGE_SIZE <= end) { 103 set_pte_at(&init_mm, addr, pte, zero_pte); 104 addr += PAGE_SIZE; 105 pte = pte_offset_kernel(pmd, addr); 106 } 107 } 108 109 static int __ref zero_pmd_populate(pud_t *pud, unsigned long addr, 110 unsigned long end) 111 { 112 pmd_t *pmd = pmd_offset(pud, addr); 113 unsigned long next; 114 115 do { 116 next = pmd_addr_end(addr, end); 117 118 if (IS_ALIGNED(addr, PMD_SIZE) && end - addr >= PMD_SIZE) { 119 pmd_populate_kernel(&init_mm, pmd, 120 lm_alias(kasan_early_shadow_pte)); 121 continue; 122 } 123 124 if (pmd_none(*pmd)) { 125 pte_t *p; 126 127 if (slab_is_available()) 128 p = pte_alloc_one_kernel(&init_mm); 129 else 130 p = early_alloc(PAGE_SIZE, NUMA_NO_NODE); 131 if (!p) 132 return -ENOMEM; 133 134 pmd_populate_kernel(&init_mm, pmd, p); 135 } 136 zero_pte_populate(pmd, addr, next); 137 } while (pmd++, addr = next, addr != end); 138 139 return 0; 140 } 141 142 static int __ref zero_pud_populate(p4d_t *p4d, unsigned long addr, 143 unsigned long end) 144 { 145 pud_t *pud = pud_offset(p4d, addr); 146 unsigned long next; 147 148 do { 149 next = pud_addr_end(addr, end); 150 if (IS_ALIGNED(addr, PUD_SIZE) && end - addr >= PUD_SIZE) { 151 pmd_t *pmd; 152 153 pud_populate(&init_mm, pud, 154 lm_alias(kasan_early_shadow_pmd)); 155 pmd = pmd_offset(pud, addr); 156 pmd_populate_kernel(&init_mm, pmd, 157 lm_alias(kasan_early_shadow_pte)); 158 continue; 159 } 160 161 if (pud_none(*pud)) { 162 pmd_t *p; 163 164 if (slab_is_available()) { 165 p = pmd_alloc(&init_mm, pud, addr); 166 if (!p) 167 return -ENOMEM; 168 } else { 169 pud_populate(&init_mm, pud, 170 early_alloc(PAGE_SIZE, NUMA_NO_NODE)); 171 } 172 } 173 zero_pmd_populate(pud, addr, next); 174 } while (pud++, addr = next, addr != end); 175 176 return 0; 177 } 178 179 static int __ref zero_p4d_populate(pgd_t *pgd, unsigned long addr, 180 unsigned long end) 181 { 182 p4d_t *p4d = p4d_offset(pgd, addr); 183 unsigned long next; 184 185 do { 186 next = p4d_addr_end(addr, end); 187 if (IS_ALIGNED(addr, P4D_SIZE) && end - addr >= P4D_SIZE) { 188 pud_t *pud; 189 pmd_t *pmd; 190 191 p4d_populate(&init_mm, p4d, 192 lm_alias(kasan_early_shadow_pud)); 193 pud = pud_offset(p4d, addr); 194 pud_populate(&init_mm, pud, 195 lm_alias(kasan_early_shadow_pmd)); 196 pmd = pmd_offset(pud, addr); 197 pmd_populate_kernel(&init_mm, pmd, 198 lm_alias(kasan_early_shadow_pte)); 199 continue; 200 } 201 202 if (p4d_none(*p4d)) { 203 pud_t *p; 204 205 if (slab_is_available()) { 206 p = pud_alloc(&init_mm, p4d, addr); 207 if (!p) 208 return -ENOMEM; 209 } else { 210 p4d_populate(&init_mm, p4d, 211 early_alloc(PAGE_SIZE, NUMA_NO_NODE)); 212 } 213 } 214 zero_pud_populate(p4d, addr, next); 215 } while (p4d++, addr = next, addr != end); 216 217 return 0; 218 } 219 220 /** 221 * kasan_populate_early_shadow - populate shadow memory region with 222 * kasan_early_shadow_page 223 * @shadow_start: start of the memory range to populate 224 * @shadow_end: end of the memory range to populate 225 */ 226 int __ref kasan_populate_early_shadow(const void *shadow_start, 227 const void *shadow_end) 228 { 229 unsigned long addr = (unsigned long)shadow_start; 230 unsigned long end = (unsigned long)shadow_end; 231 pgd_t *pgd = pgd_offset_k(addr); 232 unsigned long next; 233 234 do { 235 next = pgd_addr_end(addr, end); 236 237 if (IS_ALIGNED(addr, PGDIR_SIZE) && end - addr >= PGDIR_SIZE) { 238 p4d_t *p4d; 239 pud_t *pud; 240 pmd_t *pmd; 241 242 /* 243 * kasan_early_shadow_pud should be populated with pmds 244 * at this moment. 245 * [pud,pmd]_populate*() below needed only for 246 * 3,2 - level page tables where we don't have 247 * puds,pmds, so pgd_populate(), pud_populate() 248 * is noops. 249 */ 250 pgd_populate(&init_mm, pgd, 251 lm_alias(kasan_early_shadow_p4d)); 252 p4d = p4d_offset(pgd, addr); 253 p4d_populate(&init_mm, p4d, 254 lm_alias(kasan_early_shadow_pud)); 255 pud = pud_offset(p4d, addr); 256 pud_populate(&init_mm, pud, 257 lm_alias(kasan_early_shadow_pmd)); 258 pmd = pmd_offset(pud, addr); 259 pmd_populate_kernel(&init_mm, pmd, 260 lm_alias(kasan_early_shadow_pte)); 261 continue; 262 } 263 264 if (pgd_none(*pgd)) { 265 p4d_t *p; 266 267 if (slab_is_available()) { 268 p = p4d_alloc(&init_mm, pgd, addr); 269 if (!p) 270 return -ENOMEM; 271 } else { 272 pgd_populate(&init_mm, pgd, 273 early_alloc(PAGE_SIZE, NUMA_NO_NODE)); 274 } 275 } 276 zero_p4d_populate(pgd, addr, next); 277 } while (pgd++, addr = next, addr != end); 278 279 return 0; 280 } 281 282 static void kasan_free_pte(pte_t *pte_start, pmd_t *pmd) 283 { 284 pte_t *pte; 285 int i; 286 287 for (i = 0; i < PTRS_PER_PTE; i++) { 288 pte = pte_start + i; 289 if (!pte_none(*pte)) 290 return; 291 } 292 293 pte_free_kernel(&init_mm, (pte_t *)page_to_virt(pmd_page(*pmd))); 294 pmd_clear(pmd); 295 } 296 297 static void kasan_free_pmd(pmd_t *pmd_start, pud_t *pud) 298 { 299 pmd_t *pmd; 300 int i; 301 302 for (i = 0; i < PTRS_PER_PMD; i++) { 303 pmd = pmd_start + i; 304 if (!pmd_none(*pmd)) 305 return; 306 } 307 308 pmd_free(&init_mm, (pmd_t *)page_to_virt(pud_page(*pud))); 309 pud_clear(pud); 310 } 311 312 static void kasan_free_pud(pud_t *pud_start, p4d_t *p4d) 313 { 314 pud_t *pud; 315 int i; 316 317 for (i = 0; i < PTRS_PER_PUD; i++) { 318 pud = pud_start + i; 319 if (!pud_none(*pud)) 320 return; 321 } 322 323 pud_free(&init_mm, (pud_t *)page_to_virt(p4d_page(*p4d))); 324 p4d_clear(p4d); 325 } 326 327 static void kasan_free_p4d(p4d_t *p4d_start, pgd_t *pgd) 328 { 329 p4d_t *p4d; 330 int i; 331 332 for (i = 0; i < PTRS_PER_P4D; i++) { 333 p4d = p4d_start + i; 334 if (!p4d_none(*p4d)) 335 return; 336 } 337 338 p4d_free(&init_mm, (p4d_t *)page_to_virt(pgd_page(*pgd))); 339 pgd_clear(pgd); 340 } 341 342 static void kasan_remove_pte_table(pte_t *pte, unsigned long addr, 343 unsigned long end) 344 { 345 unsigned long next; 346 347 for (; addr < end; addr = next, pte++) { 348 next = (addr + PAGE_SIZE) & PAGE_MASK; 349 if (next > end) 350 next = end; 351 352 if (!pte_present(*pte)) 353 continue; 354 355 if (WARN_ON(!kasan_early_shadow_page_entry(*pte))) 356 continue; 357 pte_clear(&init_mm, addr, pte); 358 } 359 } 360 361 static void kasan_remove_pmd_table(pmd_t *pmd, unsigned long addr, 362 unsigned long end) 363 { 364 unsigned long next; 365 366 for (; addr < end; addr = next, pmd++) { 367 pte_t *pte; 368 369 next = pmd_addr_end(addr, end); 370 371 if (!pmd_present(*pmd)) 372 continue; 373 374 if (kasan_pte_table(*pmd)) { 375 if (IS_ALIGNED(addr, PMD_SIZE) && 376 IS_ALIGNED(next, PMD_SIZE)) { 377 pmd_clear(pmd); 378 continue; 379 } 380 } 381 pte = pte_offset_kernel(pmd, addr); 382 kasan_remove_pte_table(pte, addr, next); 383 kasan_free_pte(pte_offset_kernel(pmd, 0), pmd); 384 } 385 } 386 387 static void kasan_remove_pud_table(pud_t *pud, unsigned long addr, 388 unsigned long end) 389 { 390 unsigned long next; 391 392 for (; addr < end; addr = next, pud++) { 393 pmd_t *pmd, *pmd_base; 394 395 next = pud_addr_end(addr, end); 396 397 if (!pud_present(*pud)) 398 continue; 399 400 if (kasan_pmd_table(*pud)) { 401 if (IS_ALIGNED(addr, PUD_SIZE) && 402 IS_ALIGNED(next, PUD_SIZE)) { 403 pud_clear(pud); 404 continue; 405 } 406 } 407 pmd = pmd_offset(pud, addr); 408 pmd_base = pmd_offset(pud, 0); 409 kasan_remove_pmd_table(pmd, addr, next); 410 kasan_free_pmd(pmd_base, pud); 411 } 412 } 413 414 static void kasan_remove_p4d_table(p4d_t *p4d, unsigned long addr, 415 unsigned long end) 416 { 417 unsigned long next; 418 419 for (; addr < end; addr = next, p4d++) { 420 pud_t *pud; 421 422 next = p4d_addr_end(addr, end); 423 424 if (!p4d_present(*p4d)) 425 continue; 426 427 if (kasan_pud_table(*p4d)) { 428 if (IS_ALIGNED(addr, P4D_SIZE) && 429 IS_ALIGNED(next, P4D_SIZE)) { 430 p4d_clear(p4d); 431 continue; 432 } 433 } 434 pud = pud_offset(p4d, addr); 435 kasan_remove_pud_table(pud, addr, next); 436 kasan_free_pud(pud_offset(p4d, 0), p4d); 437 } 438 } 439 440 void kasan_remove_zero_shadow(void *start, unsigned long size) 441 { 442 unsigned long addr, end, next; 443 pgd_t *pgd; 444 445 addr = (unsigned long)kasan_mem_to_shadow(start); 446 end = addr + (size >> KASAN_SHADOW_SCALE_SHIFT); 447 448 if (WARN_ON((unsigned long)start % KASAN_MEMORY_PER_SHADOW_PAGE) || 449 WARN_ON(size % KASAN_MEMORY_PER_SHADOW_PAGE)) 450 return; 451 452 for (; addr < end; addr = next) { 453 p4d_t *p4d; 454 455 next = pgd_addr_end(addr, end); 456 457 pgd = pgd_offset_k(addr); 458 if (!pgd_present(*pgd)) 459 continue; 460 461 if (kasan_p4d_table(*pgd)) { 462 if (IS_ALIGNED(addr, PGDIR_SIZE) && 463 IS_ALIGNED(next, PGDIR_SIZE)) { 464 pgd_clear(pgd); 465 continue; 466 } 467 } 468 469 p4d = p4d_offset(pgd, addr); 470 kasan_remove_p4d_table(p4d, addr, next); 471 kasan_free_p4d(p4d_offset(pgd, 0), pgd); 472 } 473 } 474 475 int kasan_add_zero_shadow(void *start, unsigned long size) 476 { 477 int ret; 478 void *shadow_start, *shadow_end; 479 480 shadow_start = kasan_mem_to_shadow(start); 481 shadow_end = shadow_start + (size >> KASAN_SHADOW_SCALE_SHIFT); 482 483 if (WARN_ON((unsigned long)start % KASAN_MEMORY_PER_SHADOW_PAGE) || 484 WARN_ON(size % KASAN_MEMORY_PER_SHADOW_PAGE)) 485 return -EINVAL; 486 487 ret = kasan_populate_early_shadow(shadow_start, shadow_end); 488 if (ret) 489 kasan_remove_zero_shadow(start, size); 490 return ret; 491 } 492