| /* |
| * This file contains shadow memory manipulation code. |
| * |
| * Copyright (c) 2014 Samsung Electronics Co., Ltd. |
| * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> |
| * |
| * Some code borrowed from https://github.com/xairy/kasan-prototype by |
| * Andrey Konovalov <adech.fo@gmail.com> |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| */ |
| |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| #define DISABLE_BRANCH_PROFILING |
| |
| #include <linux/export.h> |
| #include <linux/interrupt.h> |
| #include <linux/init.h> |
| #include <linux/kasan.h> |
| #include <linux/kernel.h> |
| #include <linux/kmemleak.h> |
| #include <linux/linkage.h> |
| #include <linux/memblock.h> |
| #include <linux/memory.h> |
| #include <linux/mm.h> |
| #include <linux/module.h> |
| #include <linux/printk.h> |
| #include <linux/sched.h> |
| #include <linux/slab.h> |
| #include <linux/stacktrace.h> |
| #include <linux/string.h> |
| #include <linux/types.h> |
| #include <linux/vmalloc.h> |
| |
| #include "kasan.h" |
| #include "../slab.h" |
| |
| /* |
| * Poisons the shadow memory for 'size' bytes starting from 'addr'. |
| * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE. |
| */ |
| static void kasan_poison_shadow(const void *address, size_t size, u8 value) |
| { |
| void *shadow_start, *shadow_end; |
| |
| shadow_start = kasan_mem_to_shadow(address); |
| shadow_end = kasan_mem_to_shadow(address + size); |
| |
| memset(shadow_start, value, shadow_end - shadow_start); |
| } |
| |
| void kasan_unpoison_shadow(const void *address, size_t size) |
| { |
| kasan_poison_shadow(address, size, 0); |
| |
| if (size & KASAN_SHADOW_MASK) { |
| u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size); |
| *shadow = size & KASAN_SHADOW_MASK; |
| } |
| } |
| |
| static void __kasan_unpoison_stack(struct task_struct *task, void *sp) |
| { |
| void *base = task_stack_page(task); |
| size_t size = sp - base; |
| |
| kasan_unpoison_shadow(base, size); |
| } |
| |
| /* Unpoison the entire stack for a task. */ |
| void kasan_unpoison_task_stack(struct task_struct *task) |
| { |
| __kasan_unpoison_stack(task, task_stack_page(task) + THREAD_SIZE); |
| } |
| |
| /* Unpoison the stack for the current task beyond a watermark sp value. */ |
| asmlinkage void kasan_unpoison_remaining_stack(void *sp) |
| { |
| __kasan_unpoison_stack(current, sp); |
| } |
| |
| /* |
| * All functions below always inlined so compiler could |
| * perform better optimizations in each of __asan_loadX/__assn_storeX |
| * depending on memory access size X. |
| */ |
| |
| static __always_inline bool memory_is_poisoned_1(unsigned long addr) |
| { |
| s8 shadow_value = *(s8 *)kasan_mem_to_shadow((void *)addr); |
| |
| if (unlikely(shadow_value)) { |
| s8 last_accessible_byte = addr & KASAN_SHADOW_MASK; |
| return unlikely(last_accessible_byte >= shadow_value); |
| } |
| |
| return false; |
| } |
| |
| static __always_inline bool memory_is_poisoned_2(unsigned long addr) |
| { |
| u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr); |
| |
| if (unlikely(*shadow_addr)) { |
| if (memory_is_poisoned_1(addr + 1)) |
| return true; |
| |
| /* |
| * If single shadow byte covers 2-byte access, we don't |
| * need to do anything more. Otherwise, test the first |
| * shadow byte. |
| */ |
| if (likely(((addr + 1) & KASAN_SHADOW_MASK) != 0)) |
| return false; |
| |
| return unlikely(*(u8 *)shadow_addr); |
| } |
| |
| return false; |
| } |
| |
| static __always_inline bool memory_is_poisoned_4(unsigned long addr) |
| { |
| u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr); |
| |
| if (unlikely(*shadow_addr)) { |
| if (memory_is_poisoned_1(addr + 3)) |
| return true; |
| |
| /* |
| * If single shadow byte covers 4-byte access, we don't |
| * need to do anything more. Otherwise, test the first |
| * shadow byte. |
| */ |
| if (likely(((addr + 3) & KASAN_SHADOW_MASK) >= 3)) |
| return false; |
| |
| return unlikely(*(u8 *)shadow_addr); |
| } |
| |
| return false; |
| } |
| |
| static __always_inline bool memory_is_poisoned_8(unsigned long addr) |
| { |
| u16 *shadow_addr = (u16 *)kasan_mem_to_shadow((void *)addr); |
| |
| if (unlikely(*shadow_addr)) { |
| if (memory_is_poisoned_1(addr + 7)) |
| return true; |
| |
| /* |
| * If single shadow byte covers 8-byte access, we don't |
| * need to do anything more. Otherwise, test the first |
| * shadow byte. |
| */ |
| if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE))) |
| return false; |
| |
| return unlikely(*(u8 *)shadow_addr); |
| } |
| |
| return false; |
| } |
| |
| static __always_inline bool memory_is_poisoned_16(unsigned long addr) |
| { |
| u32 *shadow_addr = (u32 *)kasan_mem_to_shadow((void *)addr); |
| |
| if (unlikely(*shadow_addr)) { |
| u16 shadow_first_bytes = *(u16 *)shadow_addr; |
| |
| if (unlikely(shadow_first_bytes)) |
| return true; |
| |
| /* |
| * If two shadow bytes covers 16-byte access, we don't |
| * need to do anything more. Otherwise, test the last |
| * shadow byte. |
| */ |
| if (likely(IS_ALIGNED(addr, KASAN_SHADOW_SCALE_SIZE))) |
| return false; |
| |
| return memory_is_poisoned_1(addr + 15); |
| } |
| |
| return false; |
| } |
| |
| static __always_inline unsigned long bytes_is_zero(const u8 *start, |
| size_t size) |
| { |
| while (size) { |
| if (unlikely(*start)) |
| return (unsigned long)start; |
| start++; |
| size--; |
| } |
| |
| return 0; |
| } |
| |
| static __always_inline unsigned long memory_is_zero(const void *start, |
| const void *end) |
| { |
| unsigned int words; |
| unsigned long ret; |
| unsigned int prefix = (unsigned long)start % 8; |
| |
| if (end - start <= 16) |
| return bytes_is_zero(start, end - start); |
| |
| if (prefix) { |
| prefix = 8 - prefix; |
| ret = bytes_is_zero(start, prefix); |
| if (unlikely(ret)) |
| return ret; |
| start += prefix; |
| } |
| |
| words = (end - start) / 8; |
| while (words) { |
| if (unlikely(*(u64 *)start)) |
| return bytes_is_zero(start, 8); |
| start += 8; |
| words--; |
| } |
| |
| return bytes_is_zero(start, (end - start) % 8); |
| } |
| |
| static __always_inline bool memory_is_poisoned_n(unsigned long addr, |
| size_t size) |
| { |
| unsigned long ret; |
| |
| ret = memory_is_zero(kasan_mem_to_shadow((void *)addr), |
| kasan_mem_to_shadow((void *)addr + size - 1) + 1); |
| |
| if (unlikely(ret)) { |
| unsigned long last_byte = addr + size - 1; |
| s8 *last_shadow = (s8 *)kasan_mem_to_shadow((void *)last_byte); |
| |
| if (unlikely(ret != (unsigned long)last_shadow || |
| ((long)(last_byte & KASAN_SHADOW_MASK) >= *last_shadow))) |
| return true; |
| } |
| return false; |
| } |
| |
| static __always_inline bool memory_is_poisoned(unsigned long addr, size_t size) |
| { |
| if (__builtin_constant_p(size)) { |
| switch (size) { |
| case 1: |
| return memory_is_poisoned_1(addr); |
| case 2: |
| return memory_is_poisoned_2(addr); |
| case 4: |
| return memory_is_poisoned_4(addr); |
| case 8: |
| return memory_is_poisoned_8(addr); |
| case 16: |
| return memory_is_poisoned_16(addr); |
| default: |
| BUILD_BUG(); |
| } |
| } |
| |
| return memory_is_poisoned_n(addr, size); |
| } |
| |
| |
| static __always_inline void check_memory_region(unsigned long addr, |
| size_t size, bool write) |
| { |
| if (unlikely(size == 0)) |
| return; |
| |
| if (unlikely((void *)addr < |
| kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) { |
| kasan_report(addr, size, write, _RET_IP_); |
| return; |
| } |
| |
| if (likely(!memory_is_poisoned(addr, size))) |
| return; |
| |
| kasan_report(addr, size, write, _RET_IP_); |
| } |
| |
| void __asan_loadN(unsigned long addr, size_t size); |
| void __asan_storeN(unsigned long addr, size_t size); |
| |
| #undef memset |
| void *memset(void *addr, int c, size_t len) |
| { |
| __asan_storeN((unsigned long)addr, len); |
| |
| return __memset(addr, c, len); |
| } |
| |
| #undef memmove |
| void *memmove(void *dest, const void *src, size_t len) |
| { |
| __asan_loadN((unsigned long)src, len); |
| __asan_storeN((unsigned long)dest, len); |
| |
| return __memmove(dest, src, len); |
| } |
| |
| #undef memcpy |
| void *memcpy(void *dest, const void *src, size_t len) |
| { |
| __asan_loadN((unsigned long)src, len); |
| __asan_storeN((unsigned long)dest, len); |
| |
| return __memcpy(dest, src, len); |
| } |
| |
| void kasan_alloc_pages(struct page *page, unsigned int order) |
| { |
| if (likely(!PageHighMem(page))) |
| kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order); |
| } |
| |
| void kasan_free_pages(struct page *page, unsigned int order) |
| { |
| if (likely(!PageHighMem(page))) |
| kasan_poison_shadow(page_address(page), |
| PAGE_SIZE << order, |
| KASAN_FREE_PAGE); |
| } |
| |
| #ifdef CONFIG_SLAB |
| /* |
| * Adaptive redzone policy taken from the userspace AddressSanitizer runtime. |
| * For larger allocations larger redzones are used. |
| */ |
| static size_t optimal_redzone(size_t object_size) |
| { |
| int rz = |
| object_size <= 64 - 16 ? 16 : |
| object_size <= 128 - 32 ? 32 : |
| object_size <= 512 - 64 ? 64 : |
| object_size <= 4096 - 128 ? 128 : |
| object_size <= (1 << 14) - 256 ? 256 : |
| object_size <= (1 << 15) - 512 ? 512 : |
| object_size <= (1 << 16) - 1024 ? 1024 : 2048; |
| return rz; |
| } |
| |
| void kasan_cache_create(struct kmem_cache *cache, size_t *size, |
| unsigned long *flags) |
| { |
| int redzone_adjust; |
| /* Make sure the adjusted size is still less than |
| * KMALLOC_MAX_CACHE_SIZE. |
| * TODO: this check is only useful for SLAB, but not SLUB. We'll need |
| * to skip it for SLUB when it starts using kasan_cache_create(). |
| */ |
| if (*size > KMALLOC_MAX_CACHE_SIZE - |
| sizeof(struct kasan_alloc_meta) - |
| sizeof(struct kasan_free_meta)) |
| return; |
| *flags |= SLAB_KASAN; |
| /* Add alloc meta. */ |
| cache->kasan_info.alloc_meta_offset = *size; |
| *size += sizeof(struct kasan_alloc_meta); |
| |
| /* Add free meta. */ |
| if (cache->flags & SLAB_DESTROY_BY_RCU || cache->ctor || |
| cache->object_size < sizeof(struct kasan_free_meta)) { |
| cache->kasan_info.free_meta_offset = *size; |
| *size += sizeof(struct kasan_free_meta); |
| } |
| redzone_adjust = optimal_redzone(cache->object_size) - |
| (*size - cache->object_size); |
| if (redzone_adjust > 0) |
| *size += redzone_adjust; |
| *size = min(KMALLOC_MAX_CACHE_SIZE, |
| max(*size, |
| cache->object_size + |
| optimal_redzone(cache->object_size))); |
| } |
| #endif |
| |
| void kasan_poison_slab(struct page *page) |
| { |
| kasan_poison_shadow(page_address(page), |
| PAGE_SIZE << compound_order(page), |
| KASAN_KMALLOC_REDZONE); |
| } |
| |
| void kasan_unpoison_object_data(struct kmem_cache *cache, void *object) |
| { |
| kasan_unpoison_shadow(object, cache->object_size); |
| } |
| |
| void kasan_poison_object_data(struct kmem_cache *cache, void *object) |
| { |
| kasan_poison_shadow(object, |
| round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE), |
| KASAN_KMALLOC_REDZONE); |
| #ifdef CONFIG_SLAB |
| if (cache->flags & SLAB_KASAN) { |
| struct kasan_alloc_meta *alloc_info = |
| get_alloc_info(cache, object); |
| alloc_info->state = KASAN_STATE_INIT; |
| } |
| #endif |
| } |
| |
| #ifdef CONFIG_SLAB |
| static inline int in_irqentry_text(unsigned long ptr) |
| { |
| return (ptr >= (unsigned long)&__irqentry_text_start && |
| ptr < (unsigned long)&__irqentry_text_end) || |
| (ptr >= (unsigned long)&__softirqentry_text_start && |
| ptr < (unsigned long)&__softirqentry_text_end); |
| } |
| |
| static inline void filter_irq_stacks(struct stack_trace *trace) |
| { |
| int i; |
| |
| if (!trace->nr_entries) |
| return; |
| for (i = 0; i < trace->nr_entries; i++) |
| if (in_irqentry_text(trace->entries[i])) { |
| /* Include the irqentry function into the stack. */ |
| trace->nr_entries = i + 1; |
| break; |
| } |
| } |
| |
| static inline depot_stack_handle_t save_stack(gfp_t flags) |
| { |
| unsigned long entries[KASAN_STACK_DEPTH]; |
| struct stack_trace trace = { |
| .nr_entries = 0, |
| .entries = entries, |
| .max_entries = KASAN_STACK_DEPTH, |
| .skip = 0 |
| }; |
| |
| save_stack_trace(&trace); |
| filter_irq_stacks(&trace); |
| if (trace.nr_entries != 0 && |
| trace.entries[trace.nr_entries-1] == ULONG_MAX) |
| trace.nr_entries--; |
| |
| return depot_save_stack(&trace, flags); |
| } |
| |
| static inline void set_track(struct kasan_track *track, gfp_t flags) |
| { |
| track->pid = current->pid; |
| track->stack = save_stack(flags); |
| } |
| |
| struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache, |
| const void *object) |
| { |
| BUILD_BUG_ON(sizeof(struct kasan_alloc_meta) > 32); |
| return (void *)object + cache->kasan_info.alloc_meta_offset; |
| } |
| |
| struct kasan_free_meta *get_free_info(struct kmem_cache *cache, |
| const void *object) |
| { |
| BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32); |
| return (void *)object + cache->kasan_info.free_meta_offset; |
| } |
| #endif |
| |
| void kasan_slab_alloc(struct kmem_cache *cache, void *object, gfp_t flags) |
| { |
| kasan_kmalloc(cache, object, cache->object_size, flags); |
| } |
| |
| void kasan_slab_free(struct kmem_cache *cache, void *object) |
| { |
| unsigned long size = cache->object_size; |
| unsigned long rounded_up_size = round_up(size, KASAN_SHADOW_SCALE_SIZE); |
| |
| /* RCU slabs could be legally used after free within the RCU period */ |
| if (unlikely(cache->flags & SLAB_DESTROY_BY_RCU)) |
| return; |
| |
| #ifdef CONFIG_SLAB |
| if (cache->flags & SLAB_KASAN) { |
| struct kasan_free_meta *free_info = |
| get_free_info(cache, object); |
| struct kasan_alloc_meta *alloc_info = |
| get_alloc_info(cache, object); |
| alloc_info->state = KASAN_STATE_FREE; |
| set_track(&free_info->track); |
| } |
| #endif |
| |
| kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE); |
| } |
| |
| void kasan_kmalloc(struct kmem_cache *cache, const void *object, size_t size, |
| gfp_t flags) |
| { |
| unsigned long redzone_start; |
| unsigned long redzone_end; |
| |
| if (unlikely(object == NULL)) |
| return; |
| |
| redzone_start = round_up((unsigned long)(object + size), |
| KASAN_SHADOW_SCALE_SIZE); |
| redzone_end = round_up((unsigned long)object + cache->object_size, |
| KASAN_SHADOW_SCALE_SIZE); |
| |
| kasan_unpoison_shadow(object, size); |
| kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start, |
| KASAN_KMALLOC_REDZONE); |
| #ifdef CONFIG_SLAB |
| if (cache->flags & SLAB_KASAN) { |
| struct kasan_alloc_meta *alloc_info = |
| get_alloc_info(cache, object); |
| |
| alloc_info->state = KASAN_STATE_ALLOC; |
| alloc_info->alloc_size = size; |
| set_track(&alloc_info->track, flags); |
| } |
| #endif |
| } |
| EXPORT_SYMBOL(kasan_kmalloc); |
| |
| void kasan_kmalloc_large(const void *ptr, size_t size, gfp_t flags) |
| { |
| struct page *page; |
| unsigned long redzone_start; |
| unsigned long redzone_end; |
| |
| if (unlikely(ptr == NULL)) |
| return; |
| |
| page = virt_to_page(ptr); |
| redzone_start = round_up((unsigned long)(ptr + size), |
| KASAN_SHADOW_SCALE_SIZE); |
| redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page)); |
| |
| kasan_unpoison_shadow(ptr, size); |
| kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start, |
| KASAN_PAGE_REDZONE); |
| } |
| |
| void kasan_krealloc(const void *object, size_t size, gfp_t flags) |
| { |
| struct page *page; |
| |
| if (unlikely(object == ZERO_SIZE_PTR)) |
| return; |
| |
| page = virt_to_head_page(object); |
| |
| if (unlikely(!PageSlab(page))) |
| kasan_kmalloc_large(object, size, flags); |
| else |
| kasan_kmalloc(page->slab_cache, object, size, flags); |
| } |
| |
| void kasan_kfree(void *ptr) |
| { |
| struct page *page; |
| |
| page = virt_to_head_page(ptr); |
| |
| if (unlikely(!PageSlab(page))) |
| kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page), |
| KASAN_FREE_PAGE); |
| else |
| kasan_slab_free(page->slab_cache, ptr); |
| } |
| |
| void kasan_kfree_large(const void *ptr) |
| { |
| struct page *page = virt_to_page(ptr); |
| |
| kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page), |
| KASAN_FREE_PAGE); |
| } |
| |
| int kasan_module_alloc(void *addr, size_t size) |
| { |
| void *ret; |
| size_t shadow_size; |
| unsigned long shadow_start; |
| |
| shadow_start = (unsigned long)kasan_mem_to_shadow(addr); |
| shadow_size = round_up(size >> KASAN_SHADOW_SCALE_SHIFT, |
| PAGE_SIZE); |
| |
| if (WARN_ON(!PAGE_ALIGNED(shadow_start))) |
| return -EINVAL; |
| |
| ret = __vmalloc_node_range(shadow_size, 1, shadow_start, |
| shadow_start + shadow_size, |
| GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO, |
| PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE, |
| __builtin_return_address(0)); |
| |
| if (ret) { |
| find_vm_area(addr)->flags |= VM_KASAN; |
| kmemleak_ignore(ret); |
| return 0; |
| } |
| |
| return -ENOMEM; |
| } |
| |
| void kasan_free_shadow(const struct vm_struct *vm) |
| { |
| if (vm->flags & VM_KASAN) |
| vfree(kasan_mem_to_shadow(vm->addr)); |
| } |
| |
| static void register_global(struct kasan_global *global) |
| { |
| size_t aligned_size = round_up(global->size, KASAN_SHADOW_SCALE_SIZE); |
| |
| kasan_unpoison_shadow(global->beg, global->size); |
| |
| kasan_poison_shadow(global->beg + aligned_size, |
| global->size_with_redzone - aligned_size, |
| KASAN_GLOBAL_REDZONE); |
| } |
| |
| void __asan_register_globals(struct kasan_global *globals, size_t size) |
| { |
| int i; |
| |
| for (i = 0; i < size; i++) |
| register_global(&globals[i]); |
| } |
| EXPORT_SYMBOL(__asan_register_globals); |
| |
| void __asan_unregister_globals(struct kasan_global *globals, size_t size) |
| { |
| } |
| EXPORT_SYMBOL(__asan_unregister_globals); |
| |
| #define DEFINE_ASAN_LOAD_STORE(size) \ |
| void __asan_load##size(unsigned long addr) \ |
| { \ |
| check_memory_region(addr, size, false); \ |
| } \ |
| EXPORT_SYMBOL(__asan_load##size); \ |
| __alias(__asan_load##size) \ |
| void __asan_load##size##_noabort(unsigned long); \ |
| EXPORT_SYMBOL(__asan_load##size##_noabort); \ |
| void __asan_store##size(unsigned long addr) \ |
| { \ |
| check_memory_region(addr, size, true); \ |
| } \ |
| EXPORT_SYMBOL(__asan_store##size); \ |
| __alias(__asan_store##size) \ |
| void __asan_store##size##_noabort(unsigned long); \ |
| EXPORT_SYMBOL(__asan_store##size##_noabort) |
| |
| DEFINE_ASAN_LOAD_STORE(1); |
| DEFINE_ASAN_LOAD_STORE(2); |
| DEFINE_ASAN_LOAD_STORE(4); |
| DEFINE_ASAN_LOAD_STORE(8); |
| DEFINE_ASAN_LOAD_STORE(16); |
| |
| void __asan_loadN(unsigned long addr, size_t size) |
| { |
| check_memory_region(addr, size, false); |
| } |
| EXPORT_SYMBOL(__asan_loadN); |
| |
| __alias(__asan_loadN) |
| void __asan_loadN_noabort(unsigned long, size_t); |
| EXPORT_SYMBOL(__asan_loadN_noabort); |
| |
| void __asan_storeN(unsigned long addr, size_t size) |
| { |
| check_memory_region(addr, size, true); |
| } |
| EXPORT_SYMBOL(__asan_storeN); |
| |
| __alias(__asan_storeN) |
| void __asan_storeN_noabort(unsigned long, size_t); |
| EXPORT_SYMBOL(__asan_storeN_noabort); |
| |
| /* to shut up compiler complaints */ |
| void __asan_handle_no_return(void) {} |
| EXPORT_SYMBOL(__asan_handle_no_return); |
| |
| #ifdef CONFIG_MEMORY_HOTPLUG |
| static int kasan_mem_notifier(struct notifier_block *nb, |
| unsigned long action, void *data) |
| { |
| return (action == MEM_GOING_ONLINE) ? NOTIFY_BAD : NOTIFY_OK; |
| } |
| |
| static int __init kasan_memhotplug_init(void) |
| { |
| pr_err("WARNING: KASAN doesn't support memory hot-add\n"); |
| pr_err("Memory hot-add will be disabled\n"); |
| |
| hotplug_memory_notifier(kasan_mem_notifier, 0); |
| |
| return 0; |
| } |
| |
| module_init(kasan_memhotplug_init); |
| #endif |