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/sched/task.h> 8 #include <linux/vmalloc.h> 9 10 #include <asm/tlbflush.h> 11 #include <asm/sections.h> 12 13 extern pgd_t early_level4_pgt[PTRS_PER_PGD]; 14 extern struct range pfn_mapped[E820_X_MAX]; 15 16 static int __init map_range(struct range *range) 17 { 18 unsigned long start; 19 unsigned long end; 20 21 start = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->start)); 22 end = (unsigned long)kasan_mem_to_shadow(pfn_to_kaddr(range->end)); 23 24 /* 25 * end + 1 here is intentional. We check several shadow bytes in advance 26 * to slightly speed up fastpath. In some rare cases we could cross 27 * boundary of mapped shadow, so we just map some more here. 28 */ 29 return vmemmap_populate(start, end + 1, NUMA_NO_NODE); 30 } 31 32 static void __init clear_pgds(unsigned long start, 33 unsigned long end) 34 { 35 for (; start < end; start += PGDIR_SIZE) 36 pgd_clear(pgd_offset_k(start)); 37 } 38 39 static void __init kasan_map_early_shadow(pgd_t *pgd) 40 { 41 int i; 42 unsigned long start = KASAN_SHADOW_START; 43 unsigned long end = KASAN_SHADOW_END; 44 45 for (i = pgd_index(start); start < end; i++) { 46 pgd[i] = __pgd(__pa_nodebug(kasan_zero_pud) 47 | _KERNPG_TABLE); 48 start += PGDIR_SIZE; 49 } 50 } 51 52 #ifdef CONFIG_KASAN_INLINE 53 static int kasan_die_handler(struct notifier_block *self, 54 unsigned long val, 55 void *data) 56 { 57 if (val == DIE_GPF) { 58 pr_emerg("CONFIG_KASAN_INLINE enabled\n"); 59 pr_emerg("GPF could be caused by NULL-ptr deref or user memory access\n"); 60 } 61 return NOTIFY_OK; 62 } 63 64 static struct notifier_block kasan_die_notifier = { 65 .notifier_call = kasan_die_handler, 66 }; 67 #endif 68 69 void __init kasan_early_init(void) 70 { 71 int i; 72 pteval_t pte_val = __pa_nodebug(kasan_zero_page) | __PAGE_KERNEL; 73 pmdval_t pmd_val = __pa_nodebug(kasan_zero_pte) | _KERNPG_TABLE; 74 pudval_t pud_val = __pa_nodebug(kasan_zero_pmd) | _KERNPG_TABLE; 75 76 for (i = 0; i < PTRS_PER_PTE; i++) 77 kasan_zero_pte[i] = __pte(pte_val); 78 79 for (i = 0; i < PTRS_PER_PMD; i++) 80 kasan_zero_pmd[i] = __pmd(pmd_val); 81 82 for (i = 0; i < PTRS_PER_PUD; i++) 83 kasan_zero_pud[i] = __pud(pud_val); 84 85 kasan_map_early_shadow(early_level4_pgt); 86 kasan_map_early_shadow(init_level4_pgt); 87 } 88 89 void __init kasan_init(void) 90 { 91 int i; 92 93 #ifdef CONFIG_KASAN_INLINE 94 register_die_notifier(&kasan_die_notifier); 95 #endif 96 97 memcpy(early_level4_pgt, init_level4_pgt, sizeof(early_level4_pgt)); 98 load_cr3(early_level4_pgt); 99 __flush_tlb_all(); 100 101 clear_pgds(KASAN_SHADOW_START, KASAN_SHADOW_END); 102 103 kasan_populate_zero_shadow((void *)KASAN_SHADOW_START, 104 kasan_mem_to_shadow((void *)PAGE_OFFSET)); 105 106 for (i = 0; i < E820_X_MAX; i++) { 107 if (pfn_mapped[i].end == 0) 108 break; 109 110 if (map_range(&pfn_mapped[i])) 111 panic("kasan: unable to allocate shadow!"); 112 } 113 kasan_populate_zero_shadow( 114 kasan_mem_to_shadow((void *)PAGE_OFFSET + MAXMEM), 115 kasan_mem_to_shadow((void *)__START_KERNEL_map)); 116 117 vmemmap_populate((unsigned long)kasan_mem_to_shadow(_stext), 118 (unsigned long)kasan_mem_to_shadow(_end), 119 NUMA_NO_NODE); 120 121 kasan_populate_zero_shadow(kasan_mem_to_shadow((void *)MODULES_END), 122 (void *)KASAN_SHADOW_END); 123 124 load_cr3(init_level4_pgt); 125 __flush_tlb_all(); 126 127 /* 128 * kasan_zero_page has been used as early shadow memory, thus it may 129 * contain some garbage. Now we can clear and write protect it, since 130 * after the TLB flush no one should write to it. 131 */ 132 memset(kasan_zero_page, 0, PAGE_SIZE); 133 for (i = 0; i < PTRS_PER_PTE; i++) { 134 pte_t pte = __pte(__pa(kasan_zero_page) | __PAGE_KERNEL_RO); 135 set_pte(&kasan_zero_pte[i], pte); 136 } 137 /* Flush TLBs again to be sure that write protection applied. */ 138 __flush_tlb_all(); 139 140 init_task.kasan_depth = 0; 141 pr_info("KernelAddressSanitizer initialized\n"); 142 } 143