1 #define pr_fmt(fmt) "kasan: " fmt 2 #include <linux/bootmem.h> 3 #include <linux/kasan.h> 4 #include <linux/kdebug.h> 5 #include <linux/mm.h> 6 #include <linux/sched.h> 7 #include <linux/vmalloc.h> 8 9 #include <asm/tlbflush.h> 10 #include <asm/sections.h> 11 12 extern pgd_t early_level4_pgt[PTRS_PER_PGD]; 13 extern struct range pfn_mapped[E820_X_MAX]; 14 15 static int __init map_range(struct range *range) 16 { 17 unsigned long start; 18 unsigned long end; 19 20 start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start)); 21 end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end)); 22 23 /* 24 * end + 1 here is intentional. We check several shadow bytes in advance 25 * to slightly speed up fastpath. In some rare cases we could cross 26 * boundary of mapped shadow, so we just map some more here. 27 */ 28 return vmemmap_populate(start, end + 1, NUMA_NO_NODE); 29 } 30 31 static void __init clear_pgds(unsigned long start, 32 unsigned long end) 33 { 34 for (; start < end; start += PGDIR_SIZE) 35 pgd_clear(pgd_offset_k(start)); 36 } 37 38 static void __init kasan_map_early_shadow(pgd_t *pgd) 39 { 40 int i; 41 unsigned long start = KASAN_SHADOW_START; 42 unsigned long end = KASAN_SHADOW_END; 43 44 for (i = pgd_index(start); start < end; i++) { 45 pgd[i] = __pgd(__pa_nodebug(kasan_zero_pud) 46 | _KERNPG_TABLE); 47 start += PGDIR_SIZE; 48 } 49 } 50 51 #ifdef CONFIG_KASAN_INLINE 52 static int kasan_die_handler(struct notifier_block *self, 53 unsigned long val, 54 void *data) 55 { 56 if (val == DIE_GPF) { 57 pr_emerg("CONFIG_KASAN_INLINE enabled"); 58 pr_emerg("GPF could be caused by NULL-ptr deref or user memory access"); 59 } 60 return NOTIFY_OK; 61 } 62 63 static struct notifier_block kasan_die_notifier = { 64 .notifier_call = kasan_die_handler, 65 }; 66 #endif 67 68 void __init kasan_early_init(void) 69 { 70 int i; 71 pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL; 72 pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE; 73 pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE; 74 75 for (i = 0; i < PTRS_PER_PTE; i++) 76 kasan_zero_pte[i] = __pte(pte_val); 77 78 for (i = 0; i < PTRS_PER_PMD; i++) 79 kasan_zero_pmd[i] = __pmd(pmd_val); 80 81 for (i = 0; i < PTRS_PER_PUD; i++) 82 kasan_zero_pud[i] = __pud(pud_val); 83 84 kasan_map_early_shadow(early_level4_pgt); 85 kasan_map_early_shadow(init_level4_pgt); 86 } 87 88 void __init kasan_init(void) 89 { 90 int i; 91 92 #ifdef CONFIG_KASAN_INLINE 93 register_die_notifier(&kasan_die_notifier); 94 #endif 95 96 memcpy(early_level4_pgt, init_level4_pgt, sizeof(early_level4_pgt)); 97 load_cr3(early_level4_pgt); 98 __flush_tlb_all(); 99 100 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); 101 102 kasan_populate_zero_shadow((void *)KASAN_SHADOW_START, 103 kasan_mem_to_shadow((void *)PAGE_OFFSET)); 104 105 for (i = 0; i < E820_X_MAX; i++) { 106 if (pfn_mapped[i].end == 0) 107 break; 108 109 if (map_range(&pfn_mapped[i])) 110 panic("kasan: unable to allocate shadow!"); 111 } 112 kasan_populate_zero_shadow( 113 kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM), 114 kasan_mem_to_shadow((void *)__START_KERNEL_map)); 115 116 vmemmap_populate((unsigned long)kasan_mem_to_shadow(_stext), 117 (unsigned long)kasan_mem_to_shadow(_end), 118 NUMA_NO_NODE); 119 120 kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END), 121 (void *)KASAN_SHADOW_END); 122 123 memset(kasan_zero_page, 0, PAGE_SIZE); 124 125 load_cr3(init_level4_pgt); 126 __flush_tlb_all(); 127 init_task.kasan_depth = 0; 128 129 pr_info("KernelAddressSanitizer initialized\n"); 130 } 131