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