arch/x86/mm/kasan_init_64.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 #define DISABLE_BRANCH_PROFILING
   3 #define pr_fmt(fmt) "kasan: " fmt
   4
   5 /* cpu_feature_enabled() cannot be used this early */
   6 #define USE_EARLY_PGTABLE_L5
   7
   8 #include <linux/bootmem.h>
   9 #include <linux/kasan.h>
  10 #include <linux/kdebug.h>
  11 #include <linux/memblock.h>
  12 #include <linux/mm.h>
  13 #include <linux/sched.h>
  14 #include <linux/sched/task.h>
  15 #include <linux/vmalloc.h>
  16
  17 #include <asm/e820/types.h>
  18 #include <asm/pgalloc.h>
  19 #include <asm/tlbflush.h>
  20 #include <asm/sections.h>
  21 #include <asm/pgtable.h>
  22 #include <asm/cpu_entry_area.h>
  23
  24 extern struct range pfn_mapped[E820_MAX_ENTRIES];
  25
  26 static p4d_t tmp_p4d_table[MAX_PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
  27
  28 static __init void *early_alloc(size_t size, int nid, bool panic)
  29 {
  30         if (panic)
  31                 return memblock_virt_alloc_try_nid(size, size,
  32                         __pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, nid);
  33         else
  34                 return memblock_virt_alloc_try_nid_nopanic(size, size,
  35                         __pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, nid);
  36 }
  37
  38 static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
  39                                       unsigned long end, int nid)
  40 {
  41         pte_t *pte;
  42
  43         if (pmd_none(*pmd)) {
  44                 void *p;
  45
  46                 if (boot_cpu_has(X86_FEATURE_PSE) &&
  47                     ((end - addr) == PMD_SIZE) &&
  48                     IS_ALIGNED(addr, PMD_SIZE)) {
  49                         p = early_alloc(PMD_SIZE, nid, false);
  50                         if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
  51                                 return;
  52                         else if (p)
  53                                 memblock_free(__pa(p), PMD_SIZE);
  54                 }
  55
  56                 p = early_alloc(PAGE_SIZE, nid, true);
  57                 pmd_populate_kernel(&init_mm, pmd, p);
  58         }
  59
  60         pte = pte_offset_kernel(pmd, addr);
  61         do {
  62                 pte_t entry;
  63                 void *p;
  64
  65                 if (!pte_none(*pte))
  66                         continue;
  67
  68                 p = early_alloc(PAGE_SIZE, nid, true);
  69                 entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
  70                 set_pte_at(&init_mm, addr, pte, entry);
  71         } while (pte++, addr += PAGE_SIZE, addr != end);
  72 }
  73
  74 static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
  75                                       unsigned long end, int nid)
  76 {
  77         pmd_t *pmd;
  78         unsigned long next;
  79
  80         if (pud_none(*pud)) {
  81                 void *p;
  82
  83                 if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
  84                     ((end - addr) == PUD_SIZE) &&
  85                     IS_ALIGNED(addr, PUD_SIZE)) {
  86                         p = early_alloc(PUD_SIZE, nid, false);
  87                         if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
  88                                 return;
  89                         else if (p)
  90                                 memblock_free(__pa(p), PUD_SIZE);
  91                 }
  92
  93                 p = early_alloc(PAGE_SIZE, nid, true);
  94                 pud_populate(&init_mm, pud, p);
  95         }
  96
  97         pmd = pmd_offset(pud, addr);
  98         do {
  99                 next = pmd_addr_end(addr, end);
 100                 if (!pmd_large(*pmd))
 101                         kasan_populate_pmd(pmd, addr, next, nid);
 102         } while (pmd++, addr = next, addr != end);
 103 }
 104
 105 static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
 106                                       unsigned long end, int nid)
 107 {
 108         pud_t *pud;
 109         unsigned long next;
 110
 111         if (p4d_none(*p4d)) {
 112                 void *p = early_alloc(PAGE_SIZE, nid, true);
 113
 114                 p4d_populate(&init_mm, p4d, p);
 115         }
 116
 117         pud = pud_offset(p4d, addr);
 118         do {
 119                 next = pud_addr_end(addr, end);
 120                 if (!pud_large(*pud))
 121                         kasan_populate_pud(pud, addr, next, nid);
 122         } while (pud++, addr = next, addr != end);
 123 }
 124
 125 static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
 126                                       unsigned long end, int nid)
 127 {
 128         void *p;
 129         p4d_t *p4d;
 130         unsigned long next;
 131
 132         if (pgd_none(*pgd)) {
 133                 p = early_alloc(PAGE_SIZE, nid, true);
 134                 pgd_populate(&init_mm, pgd, p);
 135         }
 136
 137         p4d = p4d_offset(pgd, addr);
 138         do {
 139                 next = p4d_addr_end(addr, end);
 140                 kasan_populate_p4d(p4d, addr, next, nid);
 141         } while (p4d++, addr = next, addr != end);
 142 }
 143
 144 static void __init kasan_populate_shadow(unsigned long addr, unsigned long end,
 145                                          int nid)
 146 {
 147         pgd_t *pgd;
 148         unsigned long next;
 149
 150         addr = addr & PAGE_MASK;
 151         end = round_up(end, PAGE_SIZE);
 152         pgd = pgd_offset_k(addr);
 153         do {
 154                 next = pgd_addr_end(addr, end);
 155                 kasan_populate_pgd(pgd, addr, next, nid);
 156         } while (pgd++, addr = next, addr != end);
 157 }
 158
 159 static void __init map_range(struct range *range)
 160 {
 161         unsigned long start;
 162         unsigned long end;
 163
 164         start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
 165         end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));
 166
 167         kasan_populate_shadow(start, end, early_pfn_to_nid(range->start));
 168 }
 169
 170 static void __init clear_pgds(unsigned long start,
 171                         unsigned long end)
 172 {
 173         pgd_t *pgd;
 174         /* See comment in kasan_init() */
 175         unsigned long pgd_end = end & PGDIR_MASK;
 176
 177         for (; start < pgd_end; start += PGDIR_SIZE) {
 178                 pgd = pgd_offset_k(start);
 179                 /*
 180                  * With folded p4d, pgd_clear() is nop, use p4d_clear()
 181                  * instead.
 182                  */
 183                 if (pgtable_l5_enabled())
 184                         pgd_clear(pgd);
 185                 else
 186                         p4d_clear(p4d_offset(pgd, start));
 187         }
 188
 189         pgd = pgd_offset_k(start);
 190         for (; start < end; start += P4D_SIZE)
 191                 p4d_clear(p4d_offset(pgd, start));
 192 }
 193
 194 static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
 195 {
 196         unsigned long p4d;
 197
 198         if (!pgtable_l5_enabled())
 199                 return (p4d_t *)pgd;
 200
 201         p4d = pgd_val(*pgd) & PTE_PFN_MASK;
 202         p4d += __START_KERNEL_map - phys_base;
 203         return (p4d_t *)p4d + p4d_index(addr);
 204 }
 205
 206 static void __init kasan_early_p4d_populate(pgd_t *pgd,
 207                 unsigned long addr,
 208                 unsigned long end)
 209 {
 210         pgd_t pgd_entry;
 211         p4d_t *p4d, p4d_entry;
 212         unsigned long next;
 213
 214         if (pgd_none(*pgd)) {
 215                 pgd_entry = __pgd(_KERNPG_TABLE | __pa_nodebug(kasan_zero_p4d));
 216                 set_pgd(pgd, pgd_entry);
 217         }
 218
 219         p4d = early_p4d_offset(pgd, addr);
 220         do {
 221                 next = p4d_addr_end(addr, end);
 222
 223                 if (!p4d_none(*p4d))
 224                         continue;
 225
 226                 p4d_entry = __p4d(_KERNPG_TABLE | __pa_nodebug(kasan_zero_pud));
 227                 set_p4d(p4d, p4d_entry);
 228         } while (p4d++, addr = next, addr != end && p4d_none(*p4d));
 229 }
 230
 231 static void __init kasan_map_early_shadow(pgd_t *pgd)
 232 {
 233         /* See comment in kasan_init() */
 234         unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
 235         unsigned long end = KASAN_SHADOW_END;
 236         unsigned long next;
 237
 238         pgd += pgd_index(addr);
 239         do {
 240                 next = pgd_addr_end(addr, end);
 241                 kasan_early_p4d_populate(pgd, addr, next);
 242         } while (pgd++, addr = next, addr != end);
 243 }
 244
 245 #ifdef CONFIG_KASAN_INLINE
 246 static int kasan_die_handler(struct notifier_block *self,
 247                              unsigned long val,
 248                              void *data)
 249 {
 250         if (val == DIE_GPF) {
 251                 pr_emerg("CONFIG_KASAN_INLINE enabled\n");
 252                 pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
 253         }
 254         return NOTIFY_OK;
 255 }
 256
 257 static struct notifier_block kasan_die_notifier = {
 258         .notifier_call = kasan_die_handler,
 259 };
 260 #endif
 261
 262 void __init kasan_early_init(void)
 263 {
 264         int i;
 265         pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL | _PAGE_ENC;
 266         pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
 267         pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
 268         p4dval_t p4d_val = __pa_nodebug(kasan_zero_pud) | _KERNPG_TABLE;
 269
 270         /* Mask out unsupported __PAGE_KERNEL bits: */
 271         pte_val &= __default_kernel_pte_mask;
 272         pmd_val &= __default_kernel_pte_mask;
 273         pud_val &= __default_kernel_pte_mask;
 274         p4d_val &= __default_kernel_pte_mask;
 275
 276         for (i = 0; i < PTRS_PER_PTE; i++)
 277                 kasan_zero_pte[i] = __pte(pte_val);
 278
 279         for (i = 0; i < PTRS_PER_PMD; i++)
 280                 kasan_zero_pmd[i] = __pmd(pmd_val);
 281
 282         for (i = 0; i < PTRS_PER_PUD; i++)
 283                 kasan_zero_pud[i] = __pud(pud_val);
 284
 285         for (i = 0; pgtable_l5_enabled() && i < PTRS_PER_P4D; i++)
 286                 kasan_zero_p4d[i] = __p4d(p4d_val);
 287
 288         kasan_map_early_shadow(early_top_pgt);
 289         kasan_map_early_shadow(init_top_pgt);
 290 }
 291
 292 void __init kasan_init(void)
 293 {
 294         int i;
 295         void *shadow_cpu_entry_begin, *shadow_cpu_entry_end;
 296
 297 #ifdef CONFIG_KASAN_INLINE
 298         register_die_notifier(&kasan_die_notifier);
 299 #endif
 300
 301         memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
 302
 303         /*
 304          * We use the same shadow offset for 4- and 5-level paging to
 305          * facilitate boot-time switching between paging modes.
 306          * As result in 5-level paging mode KASAN_SHADOW_START and
 307          * KASAN_SHADOW_END are not aligned to PGD boundary.
 308          *
 309          * KASAN_SHADOW_START doesn't share PGD with anything else.
 310          * We claim whole PGD entry to make things easier.
 311          *
 312          * KASAN_SHADOW_END lands in the last PGD entry and it collides with
 313          * bunch of things like kernel code, modules, EFI mapping, etc.
 314          * We need to take extra steps to not overwrite them.
 315          */
 316         if (pgtable_l5_enabled()) {
 317                 void *ptr;
 318
 319                 ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
 320                 memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
 321                 set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
 322                                 __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
 323         }
 324
 325         load_cr3(early_top_pgt);
 326         __flush_tlb_all();
 327
 328         clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);
 329
 330         kasan_populate_zero_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
 331                         kasan_mem_to_shadow((void *)PAGE_OFFSET));
 332
 333         for (i = 0; i < E820_MAX_ENTRIES; i++) {
 334                 if (pfn_mapped[i].end == 0)
 335                         break;
 336
 337                 map_range(&pfn_mapped[i]);
 338         }
 339
 340         shadow_cpu_entry_begin = (void *)CPU_ENTRY_AREA_BASE;
 341         shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
 342         shadow_cpu_entry_begin = (void *)round_down((unsigned long)shadow_cpu_entry_begin,
 343                                                 PAGE_SIZE);
 344
 345         shadow_cpu_entry_end = (void *)(CPU_ENTRY_AREA_BASE +
 346                                         CPU_ENTRY_AREA_MAP_SIZE);
 347         shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
 348         shadow_cpu_entry_end = (void *)round_up((unsigned long)shadow_cpu_entry_end,
 349                                         PAGE_SIZE);
 350
 351         kasan_populate_zero_shadow(
 352                 kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
 353                 shadow_cpu_entry_begin);
 354
 355         kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
 356                               (unsigned long)shadow_cpu_entry_end, 0);
 357
 358         kasan_populate_zero_shadow(shadow_cpu_entry_end,
 359                                 kasan_mem_to_shadow((void *)__START_KERNEL_map));
 360
 361         kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
 362                               (unsigned long)kasan_mem_to_shadow(_end),
 363                               early_pfn_to_nid(__pa(_stext)));
 364
 365         kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
 366                                 (void *)KASAN_SHADOW_END);
 367
 368         load_cr3(init_top_pgt);
 369         __flush_tlb_all();
 370
 371         /*
 372          * kasan_zero_page has been used as early shadow memory, thus it may
 373          * contain some garbage. Now we can clear and write protect it, since
 374          * after the TLB flush no one should write to it.
 375          */
 376         memset(kasan_zero_page, 0, PAGE_SIZE);
 377         for (i = 0; i < PTRS_PER_PTE; i++) {
 378                 pte_t pte;
 379                 pgprot_t prot;
 380
 381                 prot = __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC);
 382                 pgprot_val(prot) &= __default_kernel_pte_mask;
 383
 384                 pte = __pte(__pa(kasan_zero_page) | pgprot_val(prot));
 385                 set_pte(&kasan_zero_pte[i], pte);
 386         }
 387         /* Flush TLBs again to be sure that write protection applied. */
 388         __flush_tlb_all();
 389
 390         init_task.kasan_depth = 0;
 391         pr_info("KernelAddressSanitizer initialized\n");
 392 }