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 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
  37static 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
  73static 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
 104static 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
 124static 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
 143static 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
 158static 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
 169static 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
 193static 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
 205static 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 |
 215                                        __pa_nodebug(kasan_early_shadow_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 |
 227                                        __pa_nodebug(kasan_early_shadow_pud));
 228                set_p4d(p4d, p4d_entry);
 229        } while (p4d++, addr = next, addr != end && p4d_none(*p4d));
 230}
 231
 232static void __init kasan_map_early_shadow(pgd_t *pgd)
 233{
 234        /* See comment in kasan_init() */
 235        unsigned long addr = KASAN_SHADOW_START & PGDIR_MASK;
 236        unsigned long end = KASAN_SHADOW_END;
 237        unsigned long next;
 238
 239        pgd += pgd_index(addr);
 240        do {
 241                next = pgd_addr_end(addr, end);
 242                kasan_early_p4d_populate(pgd, addr, next);
 243        } while (pgd++, addr = next, addr != end);
 244}
 245
 246#ifdef CONFIG_KASAN_INLINE
 247static int kasan_die_handler(struct notifier_block *self,
 248                             unsigned long val,
 249                             void *data)
 250{
 251        if (val == DIE_GPF) {
 252                pr_emerg("CONFIG_KASAN_INLINE enabled\n");
 253                pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n");
 254        }
 255        return NOTIFY_OK;
 256}
 257
 258static struct notifier_block kasan_die_notifier = {
 259        .notifier_call = kasan_die_handler,
 260};
 261#endif
 262
 263void __init kasan_early_init(void)
 264{
 265        int i;
 266        pteval_t pte_val = __pa_nodebug(kasan_early_shadow_page) |
 267                                __PAGE_KERNEL | _PAGE_ENC;
 268        pmdval_t pmd_val = __pa_nodebug(kasan_early_shadow_pte) | _KERNPG_TABLE;
 269        pudval_t pud_val = __pa_nodebug(kasan_early_shadow_pmd) | _KERNPG_TABLE;
 270        p4dval_t p4d_val = __pa_nodebug(kasan_early_shadow_pud) | _KERNPG_TABLE;
 271
 272        /* Mask out unsupported __PAGE_KERNEL bits: */
 273        pte_val &= __default_kernel_pte_mask;
 274        pmd_val &= __default_kernel_pte_mask;
 275        pud_val &= __default_kernel_pte_mask;
 276        p4d_val &= __default_kernel_pte_mask;
 277
 278        for (i = 0; i < PTRS_PER_PTE; i++)
 279                kasan_early_shadow_pte[i] = __pte(pte_val);
 280
 281        for (i = 0; i < PTRS_PER_PMD; i++)
 282                kasan_early_shadow_pmd[i] = __pmd(pmd_val);
 283
 284        for (i = 0; i < PTRS_PER_PUD; i++)
 285                kasan_early_shadow_pud[i] = __pud(pud_val);
 286
 287        for (i = 0; pgtable_l5_enabled() && i < PTRS_PER_P4D; i++)
 288                kasan_early_shadow_p4d[i] = __p4d(p4d_val);
 289
 290        kasan_map_early_shadow(early_top_pgt);
 291        kasan_map_early_shadow(init_top_pgt);
 292}
 293
 294void __init kasan_init(void)
 295{
 296        int i;
 297        void *shadow_cpu_entry_begin, *shadow_cpu_entry_end;
 298
 299#ifdef CONFIG_KASAN_INLINE
 300        register_die_notifier(&kasan_die_notifier);
 301#endif
 302
 303        memcpy(early_top_pgt, init_top_pgt, sizeof(early_top_pgt));
 304
 305        /*
 306         * We use the same shadow offset for 4- and 5-level paging to
 307         * facilitate boot-time switching between paging modes.
 308         * As result in 5-level paging mode KASAN_SHADOW_START and
 309         * KASAN_SHADOW_END are not aligned to PGD boundary.
 310         *
 311         * KASAN_SHADOW_START doesn't share PGD with anything else.
 312         * We claim whole PGD entry to make things easier.
 313         *
 314         * KASAN_SHADOW_END lands in the last PGD entry and it collides with
 315         * bunch of things like kernel code, modules, EFI mapping, etc.
 316         * We need to take extra steps to not overwrite them.
 317         */
 318        if (pgtable_l5_enabled()) {
 319                void *ptr;
 320
 321                ptr = (void *)pgd_page_vaddr(*pgd_offset_k(KASAN_SHADOW_END));
 322                memcpy(tmp_p4d_table, (void *)ptr, sizeof(tmp_p4d_table));
 323                set_pgd(&early_top_pgt[pgd_index(KASAN_SHADOW_END)],
 324                                __pgd(__pa(tmp_p4d_table) | _KERNPG_TABLE));
 325        }
 326
 327        load_cr3(early_top_pgt);
 328        __flush_tlb_all();
 329
 330        clear_pgds(KASAN_SHADOW_START & PGDIR_MASK, KASAN_SHADOW_END);
 331
 332        kasan_populate_early_shadow((void *)(KASAN_SHADOW_START & PGDIR_MASK),
 333                        kasan_mem_to_shadow((void *)PAGE_OFFSET));
 334
 335        for (i = 0; i < E820_MAX_ENTRIES; i++) {
 336                if (pfn_mapped[i].end == 0)
 337                        break;
 338
 339                map_range(&pfn_mapped[i]);
 340        }
 341
 342        shadow_cpu_entry_begin = (void *)CPU_ENTRY_AREA_BASE;
 343        shadow_cpu_entry_begin = kasan_mem_to_shadow(shadow_cpu_entry_begin);
 344        shadow_cpu_entry_begin = (void *)round_down(
 345                        (unsigned long)shadow_cpu_entry_begin, PAGE_SIZE);
 346
 347        shadow_cpu_entry_end = (void *)(CPU_ENTRY_AREA_BASE +
 348                                        CPU_ENTRY_AREA_MAP_SIZE);
 349        shadow_cpu_entry_end = kasan_mem_to_shadow(shadow_cpu_entry_end);
 350        shadow_cpu_entry_end = (void *)round_up(
 351                        (unsigned long)shadow_cpu_entry_end, PAGE_SIZE);
 352
 353        kasan_populate_early_shadow(
 354                kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM),
 355                shadow_cpu_entry_begin);
 356
 357        kasan_populate_shadow((unsigned long)shadow_cpu_entry_begin,
 358                              (unsigned long)shadow_cpu_entry_end, 0);
 359
 360        kasan_populate_early_shadow(shadow_cpu_entry_end,
 361                        kasan_mem_to_shadow((void *)__START_KERNEL_map));
 362
 363        kasan_populate_shadow((unsigned long)kasan_mem_to_shadow(_stext),
 364                              (unsigned long)kasan_mem_to_shadow(_end),
 365                              early_pfn_to_nid(__pa(_stext)));
 366
 367        kasan_populate_early_shadow(kasan_mem_to_shadow((void *)MODULES_END),
 368                                        (void *)KASAN_SHADOW_END);
 369
 370        load_cr3(init_top_pgt);
 371        __flush_tlb_all();
 372
 373        /*
 374         * kasan_early_shadow_page has been used as early shadow memory, thus
 375         * it may contain some garbage. Now we can clear and write protect it,
 376         * since after the TLB flush no one should write to it.
 377         */
 378        memset(kasan_early_shadow_page, 0, PAGE_SIZE);
 379        for (i = 0; i < PTRS_PER_PTE; i++) {
 380                pte_t pte;
 381                pgprot_t prot;
 382
 383                prot = __pgprot(__PAGE_KERNEL_RO | _PAGE_ENC);
 384                pgprot_val(prot) &= __default_kernel_pte_mask;
 385
 386                pte = __pte(__pa(kasan_early_shadow_page) | pgprot_val(prot));
 387                set_pte(&kasan_early_shadow_pte[i], pte);
 388        }
 389        /* Flush TLBs again to be sure that write protection applied. */
 390        __flush_tlb_all();
 391
 392        init_task.kasan_depth = 0;
 393        pr_info("KernelAddressSanitizer initialized\n");
 394}
 395