LXR linux/arch/x86/mm/kasan_init

   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
  23extern struct range pfn_mapped[E820_MAX_ENTRIES];
  24
  25static p4d_t tmp_p4d_table[MAX_PTRS_PER_P4D] __initdata __aligned(PAGE_SIZE);
  26
  27static __init void *early_alloc(size_t size, int nid, bool should_panic)
  28{
  29        void *ptr = memblock_alloc_try_nid(size, size,
  30                        __pa(MAX_DMA_ADDRESS), MEMBLOCK_ALLOC_ACCESSIBLE, nid);
  31
  32        if (!ptr && should_panic)
  33                panic("%pS: Failed to allocate page, nid=%d from=%lx\n",
  34                      (void *)_RET_IP_, nid, __pa(MAX_DMA_ADDRESS));
  35
  36        return ptr;
  37}
  38
  39static void __init kasan_populate_pmd(pmd_t *pmd, unsigned long addr,
  40                                      unsigned long end, int nid)
  41{
  42        pte_t *pte;
  43
  44        if (pmd_none(*pmd)) {
  45                void *p;
  46
  47                if (boot_cpu_has(X86_FEATURE_PSE) &&
  48                    ((end - addr) == PMD_SIZE) &&
  49                    IS_ALIGNED(addr, PMD_SIZE)) {
  50                        p = early_alloc(PMD_SIZE, nid, false);
  51                        if (p && pmd_set_huge(pmd, __pa(p), PAGE_KERNEL))
  52                                return;
  53                        else if (p)
  54                                memblock_free(__pa(p), PMD_SIZE);
  55                }
  56
  57                p = early_alloc(PAGE_SIZE, nid, true);
  58                pmd_populate_kernel(&init_mm, pmd, p);
  59        }
  60
  61        pte = pte_offset_kernel(pmd, addr);
  62        do {
  63                pte_t entry;
  64                void *p;
  65
  66                if (!pte_none(*pte))
  67                        continue;
  68
  69                p = early_alloc(PAGE_SIZE, nid, true);
  70                entry = pfn_pte(PFN_DOWN(__pa(p)), PAGE_KERNEL);
  71                set_pte_at(&init_mm, addr, pte, entry);
  72        } while (pte++, addr += PAGE_SIZE, addr != end);
  73}
  74
  75static void __init kasan_populate_pud(pud_t *pud, unsigned long addr,
  76                                      unsigned long end, int nid)
  77{
  78        pmd_t *pmd;
  79        unsigned long next;
  80
  81        if (pud_none(*pud)) {
  82                void *p;
  83
  84                if (boot_cpu_has(X86_FEATURE_GBPAGES) &&
  85                    ((end - addr) == PUD_SIZE) &&
  86                    IS_ALIGNED(addr, PUD_SIZE)) {
  87                        p = early_alloc(PUD_SIZE, nid, false);
  88                        if (p && pud_set_huge(pud, __pa(p), PAGE_KERNEL))
  89                                return;
  90                        else if (p)
  91                                memblock_free(__pa(p), PUD_SIZE);
  92                }
  93
  94                p = early_alloc(PAGE_SIZE, nid, true);
  95                pud_populate(&init_mm, pud, p);
  96        }
  97
  98        pmd = pmd_offset(pud, addr);
  99        do {
 100                next = pmd_addr_end(addr, end);
 101                if (!pmd_large(*pmd))
 102                        kasan_populate_pmd(pmd, addr, next, nid);
 103        } while (pmd++, addr = next, addr != end);
 104}
 105
 106static void __init kasan_populate_p4d(p4d_t *p4d, unsigned long addr,
 107                                      unsigned long end, int nid)
 108{
 109        pud_t *pud;
 110        unsigned long next;
 111
 112        if (p4d_none(*p4d)) {
 113                void *p = early_alloc(PAGE_SIZE, nid, true);
 114
 115                p4d_populate(&init_mm, p4d, p);
 116        }
 117
 118        pud = pud_offset(p4d, addr);
 119        do {
 120                next = pud_addr_end(addr, end);
 121                if (!pud_large(*pud))
 122                        kasan_populate_pud(pud, addr, next, nid);
 123        } while (pud++, addr = next, addr != end);
 124}
 125
 126static void __init kasan_populate_pgd(pgd_t *pgd, unsigned long addr,
 127                                      unsigned long end, int nid)
 128{
 129        void *p;
 130        p4d_t *p4d;
 131        unsigned long next;
 132
 133        if (pgd_none(*pgd)) {
 134                p = early_alloc(PAGE_SIZE, nid, true);
 135                pgd_populate(&init_mm, pgd, p);
 136        }
 137
 138        p4d = p4d_offset(pgd, addr);
 139        do {
 140                next = p4d_addr_end(addr, end);
 141                kasan_populate_p4d(p4d, addr, next, nid);
 142        } while (p4d++, addr = next, addr != end);
 143}
 144
 145static void __init kasan_populate_shadow(unsigned long addr, unsigned long end,
 146                                         int nid)
 147{
 148        pgd_t *pgd;
 149        unsigned long next;
 150
 151        addr = addr & PAGE_MASK;
 152        end = round_up(end, PAGE_SIZE);
 153        pgd = pgd_offset_k(addr);
 154        do {
 155                next = pgd_addr_end(addr, end);
 156                kasan_populate_pgd(pgd, addr, next, nid);
 157        } while (pgd++, addr = next, addr != end);
 158}
 159
 160static void __init map_range(struct range *range)
 161{
 162        unsigned long start;
 163        unsigned long end;
 164
 165        start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start));
 166        end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end));
 167
 168        kasan_populate_shadow(start, end, early_pfn_to_nid(range->start));
 169}
 170
 171static void __init clear_pgds(unsigned long start,
 172                        unsigned long end)
 173{
 174        pgd_t *pgd;
 175        /* See comment in kasan_init() */
 176        unsigned long pgd_end = end & PGDIR_MASK;
 177
 178        for (; start < pgd_end; start += PGDIR_SIZE) {
 179                pgd = pgd_offset_k(start);
 180                /*
 181                 * With folded p4d, pgd_clear() is nop, use p4d_clear()
 182                 * instead.
 183                 */
 184                if (pgtable_l5_enabled())
 185                        pgd_clear(pgd);
 186                else
 187                        p4d_clear(p4d_offset(pgd, start));
 188        }
 189
 190        pgd = pgd_offset_k(start);
 191        for (; start < end; start += P4D_SIZE)
 192                p4d_clear(p4d_offset(pgd, start));
 193}
 194
 195static inline p4d_t *early_p4d_offset(pgd_t *pgd, unsigned long addr)
 196{
 197        unsigned long p4d;
 198
 199        if (!pgtable_l5_enabled())
 200                return (p4d_t *)pgd;
 201
 202        p4d = pgd_val(*pgd) & PTE_PFN_MASK;
 203        p4d += __START_KERNEL_map - phys_base;
 204        return (p4d_t *)p4d + p4d_index(addr);
 205}
 206
 207static void __init kasan_early_p4d_populate(pgd_t *pgd,
 208                unsigned long addr,
 209                unsigned long end)
 210{
 211        pgd_t pgd_entry;
 212        p4d_t *p4d, p4d_entry;
 213        unsigned long next;
 214
 215        if (pgd_none(*pgd)) {
 216                pgd_entry = __pgd(_KERNPG_TABLE |
 217                                        __pa_nodebug(kasan_early_shadow_p4d));
 218                set_pgd(pgd, pgd_entry);
 219        }
 220
 221        p4d = early_p4d_offset(pgd, addr);
 222        do {
 223                next = p4d_addr_end(addr, end);
 224
 225                if (!p4d_none(*p4d))
 226                        continue;
 227
 228                p4d_entry = __p4d(_KERNPG_TABLE |
 229                                        __pa_nodebug(kasan_early_shadow_pud));
 230                set_p4d(p4d, p4d_entry);
 231        } while (p4d++, addr = next, addr != end && p4d_none(*p4d));
 232}
 233
 234static void __init kasan_map_early_shadow(pgd_t *pgd)
 235{
 236        /* See comment in kasan_init() */
 237        unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
 238        unsigned long end = KASAN_SHADOW_END;
 239        unsigned long next;
 240
 241        pgd += pgd_index(addr);
 242        do {
 243                next = pgd_addr_end(addr, end);
 244                kasan_early_p4d_populate(pgd, addr, next);
 245        } while (pgd++, addr = next, addr != end);
 246}
 247
 248#ifdef CONFIG_KASAN_INLINE
 249static int kasan_die_handler(struct notifier_block *self,
 250                             unsigned long val,
 251                             void *data)
 252{
 253        if (val == DIE_GPF) {
 254                pr_emerg("CONFIG_KASAN_INLINE enabled\n");
 255                pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
 256        }
 257        return NOTIFY_OK;
 258}
 259
 260static struct notifier_block kasan_die_notifier = {
 261        .notifier_call = kasan_die_handler,
 262};
 263#endif
 264
 265void __init kasan_early_init(void)
 266{
 267        int i;
 268        pteval_t pte_val = __pa_nodebug(kasan_early_shadow_page) |
 269                                __PAGE_KERNEL | _PAGE_ENC;
 270        pmdval_t pmd_val = __pa_nodebug(kasan_early_shadow_pte) | _KERNPG_TABLE;
 271        pudval_t pud_val = __pa_nodebug(kasan_early_shadow_pmd) | _KERNPG_TABLE;
 272        p4dval_t p4d_val = __pa_nodebug(kasan_early_shadow_pud) | _KERNPG_TABLE;
 273
 274        /* Mask out unsupported __PAGE_KERNEL bits: */
 275        pte_val &= __default_kernel_pte_mask;
 276        pmd_val &= __default_kernel_pte_mask;
 277        pud_val &= __default_kernel_pte_mask;
 278        p4d_val &= __default_kernel_pte_mask;
 279
 280        for (i = 0; i < PTRS_PER_PTE; i++)
 281                kasan_early_shadow_pte[i] = __pte(pte_val);
 282
 283        for (i = 0; i < PTRS_PER_PMD; i++)
 284                kasan_early_shadow_pmd[i] = __pmd(pmd_val);
 285
 286        for (i = 0; i < PTRS_PER_PUD; i++)
 287                kasan_early_shadow_pud[i] = __pud(pud_val);
 288
 289        for (i = 0; pgtable_l5_enabled() && i < PTRS_PER_P4D; i++)
 290                kasan_early_shadow_p4d[i] = __p4d(p4d_val);
 291
 292        kasan_map_early_shadow(early_top_pgt);
 293        kasan_map_early_shadow(init_top_pgt);
 294}
 295
 296void __init kasan_init(void)
 297{
 298        int i;
 299        void *shadow_cpu_entry_begin, *shadow_cpu_entry_end;
 300
 301#ifdef CONFIG_KASAN_INLINE
 302        register_die_notifier(&kasan_die_notifier);
 303#endif
 304
 305        memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
 306
 307        /*
 308         * We use the same shadow offset for 4- and 5-level paging to
 309         * facilitate boot-time switching between paging modes.
 310         * As result in 5-level paging mode KASAN_SHADOW_START and
 311         * KASAN_SHADOW_END are not aligned to PGD boundary.
 312         *
 313         * KASAN_SHADOW_START doesn't share PGD with anything else.
 314         * We claim whole PGD entry to make things easier.
 315         *
 316         * KASAN_SHADOW_END lands in the last PGD entry and it collides with
 317         * bunch of things like kernel code, modules, EFI mapping, etc.
 318         * We need to take extra steps to not overwrite them.
 319         */
 320        if (pgtable_l5_enabled()) {
 321                void *ptr;
 322
 323                ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
 324                memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
 325                set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
 326                                __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
 327        }
 328
 329        load_cr3(early_top_pgt);
 330        __flush_tlb_all();
 331
 332        clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);
 333
 334        kasan_populate_early_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
 335                        kasan_mem_to_shadow((void *)PAGE_OFFSET));
 336
 337        for (i = 0; i < E820_MAX_ENTRIES; i++) {
 338                if (pfn_mapped[i].end == 0)
 339                        break;
 340
 341                map_range(&pfn_mapped[i]);
 342        }
 343
 344        shadow_cpu_entry_begin = (void *)CPU_ENTRY_AREA_BASE;
 345        shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
 346        shadow_cpu_entry_begin = (void *)round_down(
 347                        (unsigned long)shadow_cpu_entry_begin, PAGE_SIZE);
 348
 349        shadow_cpu_entry_end = (void *)(CPU_ENTRY_AREA_BASE +
 350                                        CPU_ENTRY_AREA_MAP_SIZE);
 351        shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
 352        shadow_cpu_entry_end = (void *)round_up(
 353                        (unsigned long)shadow_cpu_entry_end, PAGE_SIZE);
 354
 355        kasan_populate_early_shadow(
 356                kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
 357                shadow_cpu_entry_begin);
 358
 359        kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
 360                              (unsigned long)shadow_cpu_entry_end, 0);
 361
 362        kasan_populate_early_shadow(shadow_cpu_entry_end,
 363                        kasan_mem_to_shadow((void *)__START_KERNEL_map));
 364
 365        kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
 366                              (unsigned long)kasan_mem_to_shadow(_end),
 367                              early_pfn_to_nid(__pa(_stext)));
 368
 369        kasan_populate_early_shadow(kasan_mem_to_shadow((void *)MODULES_END),
 370                                        (void *)KASAN_SHADOW_END);
 371
 372        load_cr3(init_top_pgt);
 373        __flush_tlb_all();
 374
 375        /*
 376         * kasan_early_shadow_page has been used as early shadow memory, thus
 377         * it may contain some garbage. Now we can clear and write protect it,
 378         * since after the TLB flush no one should write to it.
 379         */
 380        memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 381        for (i = 0; i < PTRS_PER_PTE; i++) {
 382                pte_t pte;
 383                pgprot_t prot;
 384
 385                prot = __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC);
 386                pgprot_val(prot) &= __default_kernel_pte_mask;
 387
 388                pte = __pte(__pa(kasan_early_shadow_page) | pgprot_val(prot));
 389                set_pte(&kasan_early_shadow_pte[i], pte);
 390        }
 391        /* Flush TLBs again to be sure that write protection applied. */
 392        __flush_tlb_all();
 393
 394        init_task.kasan_depth = 0;
 395        pr_info("KernelAddressSanitizer initialized\n");
 396}
 397