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 #include <linux/bootmem.h>
   5 #include <linux/kasan.h>
   6 #include <linux/kdebug.h>
   7 #include <linux/memblock.h>
   8 #include <linux/mm.h>
   9 #include <linux/sched.h>
  10 #include <linux/sched/task.h>
  11 #include <linux/vmalloc.h>
  12
  13 #include <asm/e820/types.h>
  14 #include <asm/pgalloc.h>
  15 #include <asm/tlbflush.h>
  16 #include <asm/sections.h>
  17 #include <asm/pgtable.h>
  18 #include <asm/cpu_entry_area.h>
  19
  20 extern struct range pfn_mapped[E820_MAX_ENTRIES];
  21
  22 static p4d_t tmp_p4d_table[PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
  23
  24 static __init void *early_alloc(size_t size, int nid, bool panic)
  25 {
  26         if (panic)
  27                 return memblock_virt_alloc_try_nid(size, size,
  28                         __pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, nid);
  29         else
  30                 return memblock_virt_alloc_try_nid_nopanic(size, size,
  31                         __pa(MAX_DMA_ADDRESS), BOOTMEM_ALLOC_ACCESSIBLE, nid);
  32 }
  33
  34 static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
  35                                       unsigned long end, int nid)
  36 {
  37         pte_t *pte;
  38
  39         if (pmd_none(*pmd)) {
  40                 void *p;
  41
  42                 if (boot_cpu_has(X86_FEATURE_PSE) &&
  43                     ((end - addr) == PMD_SIZE) &&
  44                     IS_ALIGNED(addr, PMD_SIZE)) {
  45                         p = early_alloc(PMD_SIZE, nid, false);
  46                         if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
  47                                 return;
  48                         else if (p)
  49                                 memblock_free(__pa(p), PMD_SIZE);
  50                 }
  51
  52                 p = early_alloc(PAGE_SIZE, nid, true);
  53                 pmd_populate_kernel(&init_mm, pmd, p);
  54         }
  55
  56         pte = pte_offset_kernel(pmd, addr);
  57         do {
  58                 pte_t entry;
  59                 void *p;
  60
  61                 if (!pte_none(*pte))
  62                         continue;
  63
  64                 p = early_alloc(PAGE_SIZE, nid, true);
  65                 entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
  66                 set_pte_at(&init_mm, addr, pte, entry);
  67         } while (pte++, addr += PAGE_SIZE, addr != end);
  68 }
  69
  70 static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
  71                                       unsigned long end, int nid)
  72 {
  73         pmd_t *pmd;
  74         unsigned long next;
  75
  76         if (pud_none(*pud)) {
  77                 void *p;
  78
  79                 if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
  80                     ((end - addr) == PUD_SIZE) &&
  81                     IS_ALIGNED(addr, PUD_SIZE)) {
  82                         p = early_alloc(PUD_SIZE, nid, false);
  83                         if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
  84                                 return;
  85                         else if (p)
  86                                 memblock_free(__pa(p), PUD_SIZE);
  87                 }
  88
  89                 p = early_alloc(PAGE_SIZE, nid, true);
  90                 pud_populate(&init_mm, pud, p);
  91         }
  92
  93         pmd = pmd_offset(pud, addr);
  94         do {
  95                 next = pmd_addr_end(addr, end);
  96                 if (!pmd_large(*pmd))
  97                         kasan_populate_pmd(pmd, addr, next, nid);
  98         } while (pmd++, addr = next, addr != end);
  99 }
 100
 101 static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
 102                                       unsigned long end, int nid)
 103 {
 104         pud_t *pud;
 105         unsigned long next;
 106
 107         if (p4d_none(*p4d)) {
 108                 void *p = early_alloc(PAGE_SIZE, nid, true);
 109
 110                 p4d_populate(&init_mm, p4d, p);
 111         }
 112
 113         pud = pud_offset(p4d, addr);
 114         do {
 115                 next = pud_addr_end(addr, end);
 116                 if (!pud_large(*pud))
 117                         kasan_populate_pud(pud, addr, next, nid);
 118         } while (pud++, addr = next, addr != end);
 119 }
 120
 121 static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
 122                                       unsigned long end, int nid)
 123 {
 124         void *p;
 125         p4d_t *p4d;
 126         unsigned long next;
 127
 128         if (pgd_none(*pgd)) {
 129                 p = early_alloc(PAGE_SIZE, nid, true);
 130                 pgd_populate(&init_mm, pgd, p);
 131         }
 132
 133         p4d = p4d_offset(pgd, addr);
 134         do {
 135                 next = p4d_addr_end(addr, end);
 136                 kasan_populate_p4d(p4d, addr, next, nid);
 137         } while (p4d++, addr = next, addr != end);
 138 }
 139
 140 static void __init kasan_populate_shadow(unsigned long addr, unsigned long end,
 141                                          int nid)
 142 {
 143         pgd_t *pgd;
 144         unsigned long next;
 145
 146         addr = addr & PAGE_MASK;
 147         end = round_up(end, PAGE_SIZE);
 148         pgd = pgd_offset_k(addr);
 149         do {
 150                 next = pgd_addr_end(addr, end);
 151                 kasan_populate_pgd(pgd, addr, next, nid);
 152         } while (pgd++, addr = next, addr != end);
 153 }
 154
 155 static void __init map_range(struct range *range)
 156 {
 157         unsigned long start;
 158         unsigned long end;
 159
 160         start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
 161         end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));
 162
 163         kasan_populate_shadow(start, end, early_pfn_to_nid(range->start));
 164 }
 165
 166 static void __init clear_pgds(unsigned long start,
 167                         unsigned long end)
 168 {
 169         pgd_t *pgd;
 170         /* See comment in kasan_init() */
 171         unsigned long pgd_end = end & PGDIR_MASK;
 172
 173         for (; start < pgd_end; start += PGDIR_SIZE) {
 174                 pgd = pgd_offset_k(start);
 175                 /*
 176                  * With folded p4d, pgd_clear() is nop, use p4d_clear()
 177                  * instead.
 178                  */
 179                 if (CONFIG_PGTABLE_LEVELS < 5)
 180                         p4d_clear(p4d_offset(pgd, start));
 181                 else
 182                         pgd_clear(pgd);
 183         }
 184
 185         pgd = pgd_offset_k(start);
 186         for (; start < end; start += P4D_SIZE)
 187                 p4d_clear(p4d_offset(pgd, start));
 188 }
 189
 190 static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
 191 {
 192         unsigned long p4d;
 193
 194         if (!IS_ENABLED(CONFIG_X86_5LEVEL))
 195                 return (p4d_t *)pgd;
 196
 197         p4d = __pa_nodebug(pgd_val(*pgd)) & PTE_PFN_MASK;
 198         p4d += __START_KERNEL_map - phys_base;
 199         return (p4d_t *)p4d + p4d_index(addr);
 200 }
 201
 202 static void __init kasan_early_p4d_populate(pgd_t *pgd,
 203                 unsigned long addr,
 204                 unsigned long end)
 205 {
 206         pgd_t pgd_entry;
 207         p4d_t *p4d, p4d_entry;
 208         unsigned long next;
 209
 210         if (pgd_none(*pgd)) {
 211                 pgd_entry = __pgd(_KERNPG_TABLE | __pa_nodebug(kasan_zero_p4d));
 212                 set_pgd(pgd, pgd_entry);
 213         }
 214
 215         p4d = early_p4d_offset(pgd, addr);
 216         do {
 217                 next = p4d_addr_end(addr, end);
 218
 219                 if (!p4d_none(*p4d))
 220                         continue;
 221
 222                 p4d_entry = __p4d(_KERNPG_TABLE | __pa_nodebug(kasan_zero_pud));
 223                 set_p4d(p4d, p4d_entry);
 224         } while (p4d++, addr = next, addr != end && p4d_none(*p4d));
 225 }
 226
 227 static void __init kasan_map_early_shadow(pgd_t *pgd)
 228 {
 229         /* See comment in kasan_init() */
 230         unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
 231         unsigned long end = KASAN_SHADOW_END;
 232         unsigned long next;
 233
 234         pgd += pgd_index(addr);
 235         do {
 236                 next = pgd_addr_end(addr, end);
 237                 kasan_early_p4d_populate(pgd, addr, next);
 238         } while (pgd++, addr = next, addr != end);
 239 }
 240
 241 #ifdef CONFIG_KASAN_INLINE
 242 static int kasan_die_handler(struct notifier_block *self,
 243                              unsigned long val,
 244                              void *data)
 245 {
 246         if (val == DIE_GPF) {
 247                 pr_emerg("CONFIG_KASAN_INLINE enabled\n");
 248                 pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
 249         }
 250         return NOTIFY_OK;
 251 }
 252
 253 static struct notifier_block kasan_die_notifier = {
 254         .notifier_call = kasan_die_handler,
 255 };
 256 #endif
 257
 258 void __init kasan_early_init(void)
 259 {
 260         int i;
 261         pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL | _PAGE_ENC;
 262         pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE;
 263         pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE;
 264         p4dval_t p4d_val = __pa_nodebug(kasan_zero_pud) | _KERNPG_TABLE;
 265
 266         /* Mask out unsupported __PAGE_KERNEL bits: */
 267         pte_val &= __default_kernel_pte_mask;
 268         pmd_val &= __default_kernel_pte_mask;
 269         pud_val &= __default_kernel_pte_mask;
 270         p4d_val &= __default_kernel_pte_mask;
 271
 272         for (i = 0; i < PTRS_PER_PTE; i++)
 273                 kasan_zero_pte[i] = __pte(pte_val);
 274
 275         for (i = 0; i < PTRS_PER_PMD; i++)
 276                 kasan_zero_pmd[i] = __pmd(pmd_val);
 277
 278         for (i = 0; i < PTRS_PER_PUD; i++)
 279                 kasan_zero_pud[i] = __pud(pud_val);
 280
 281         for (i = 0; IS_ENABLED(CONFIG_X86_5LEVEL) && i < PTRS_PER_P4D; i++)
 282                 kasan_zero_p4d[i] = __p4d(p4d_val);
 283
 284         kasan_map_early_shadow(early_top_pgt);
 285         kasan_map_early_shadow(init_top_pgt);
 286 }
 287
 288 void __init kasan_init(void)
 289 {
 290         int i;
 291         void *shadow_cpu_entry_begin, *shadow_cpu_entry_end;
 292
 293 #ifdef CONFIG_KASAN_INLINE
 294         register_die_notifier(&kasan_die_notifier);
 295 #endif
 296
 297         memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
 298
 299         /*
 300          * We use the same shadow offset for 4- and 5-level paging to
 301          * facilitate boot-time switching between paging modes.
 302          * As result in 5-level paging mode KASAN_SHADOW_START and
 303          * KASAN_SHADOW_END are not aligned to PGD boundary.
 304          *
 305          * KASAN_SHADOW_START doesn't share PGD with anything else.
 306          * We claim whole PGD entry to make things easier.
 307          *
 308          * KASAN_SHADOW_END lands in the last PGD entry and it collides with
 309          * bunch of things like kernel code, modules, EFI mapping, etc.
 310          * We need to take extra steps to not overwrite them.
 311          */
 312         if (IS_ENABLED(CONFIG_X86_5LEVEL)) {
 313                 void *ptr;
 314
 315                 ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
 316                 memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
 317                 set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
 318                                 __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
 319         }
 320
 321         load_cr3(early_top_pgt);
 322         __flush_tlb_all();
 323
 324         clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);
 325
 326         kasan_populate_zero_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
 327                         kasan_mem_to_shadow((void *)PAGE_OFFSET));
 328
 329         for (i = 0; i < E820_MAX_ENTRIES; i++) {
 330                 if (pfn_mapped[i].end == 0)
 331                         break;
 332
 333                 map_range(&pfn_mapped[i]);
 334         }
 335
 336         shadow_cpu_entry_begin = (void *)CPU_ENTRY_AREA_BASE;
 337         shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
 338         shadow_cpu_entry_begin = (void *)round_down((unsigned long)shadow_cpu_entry_begin,
 339                                                 PAGE_SIZE);
 340
 341         shadow_cpu_entry_end = (void *)(CPU_ENTRY_AREA_BASE +
 342                                         CPU_ENTRY_AREA_MAP_SIZE);
 343         shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
 344         shadow_cpu_entry_end = (void *)round_up((unsigned long)shadow_cpu_entry_end,
 345                                         PAGE_SIZE);
 346
 347         kasan_populate_zero_shadow(
 348                 kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
 349                 shadow_cpu_entry_begin);
 350
 351         kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
 352                               (unsigned long)shadow_cpu_entry_end, 0);
 353
 354         kasan_populate_zero_shadow(shadow_cpu_entry_end,
 355                                 kasan_mem_to_shadow((void *)__START_KERNEL_map));
 356
 357         kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
 358                               (unsigned long)kasan_mem_to_shadow(_end),
 359                               early_pfn_to_nid(__pa(_stext)));
 360
 361         kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END),
 362                                 (void *)KASAN_SHADOW_END);
 363
 364         load_cr3(init_top_pgt);
 365         __flush_tlb_all();
 366
 367         /*
 368          * kasan_zero_page has been used as early shadow memory, thus it may
 369          * contain some garbage. Now we can clear and write protect it, since
 370          * after the TLB flush no one should write to it.
 371          */
 372         memset(kasan_zero_page, 0, PAGE_SIZE);
 373         for (i = 0; i < PTRS_PER_PTE; i++) {
 374                 pte_t pte;
 375                 pgprot_t prot;
 376
 377                 prot = __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC);
 378                 pgprot_val(prot) &= __default_kernel_pte_mask;
 379
 380                 pte = __pte(__pa(kasan_zero_page) | pgprot_val(prot));
 381                 set_pte(&kasan_zero_pte[i], pte);
 382         }
 383         /* Flush TLBs again to be sure that write protection applied. */
 384         __flush_tlb_all();
 385
 386         init_task.kasan_depth = 0;
 387         pr_info("KernelAddressSanitizer initialized\n");
 388 }