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![Andrey Konovalov](/assets/img/avatar_default.png)
Mark all static functions in common.c and kasan.h that are used for hardware tag-based KASAN as inline to avoid unnecessary function calls. Link: https://lkml.kernel.org/r/2c94a2af0657f2b95b9337232339ff5ffa643ab5.1612546384.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov <andreyknvl@google.com> Reviewed-by: Marco Elver <elver@google.com> Cc: Alexander Potapenko <glider@google.com> Cc: Andrey Ryabinin <aryabinin@virtuozzo.com> Cc: Branislav Rankov <Branislav.Rankov@arm.com> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Evgenii Stepanov <eugenis@google.com> Cc: Kevin Brodsky <kevin.brodsky@arm.com> Cc: Peter Collingbourne <pcc@google.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Will Deacon <will.deacon@arm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
584 lines
16 KiB
C
584 lines
16 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* This file contains common KASAN code.
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*
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* Copyright (c) 2014 Samsung Electronics Co., Ltd.
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* Author: Andrey Ryabinin <ryabinin.a.a@gmail.com>
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*
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* Some code borrowed from https://github.com/xairy/kasan-prototype by
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* Andrey Konovalov <andreyknvl@gmail.com>
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*/
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#include <linux/export.h>
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#include <linux/init.h>
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#include <linux/kasan.h>
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#include <linux/kernel.h>
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#include <linux/linkage.h>
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#include <linux/memblock.h>
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#include <linux/memory.h>
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#include <linux/mm.h>
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#include <linux/module.h>
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#include <linux/printk.h>
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#include <linux/sched.h>
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#include <linux/sched/task_stack.h>
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#include <linux/slab.h>
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#include <linux/stacktrace.h>
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#include <linux/string.h>
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#include <linux/types.h>
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#include <linux/bug.h>
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#include "kasan.h"
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#include "../slab.h"
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depot_stack_handle_t kasan_save_stack(gfp_t flags)
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{
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unsigned long entries[KASAN_STACK_DEPTH];
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unsigned int nr_entries;
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nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
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nr_entries = filter_irq_stacks(entries, nr_entries);
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return stack_depot_save(entries, nr_entries, flags);
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}
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void kasan_set_track(struct kasan_track *track, gfp_t flags)
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{
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track->pid = current->pid;
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track->stack = kasan_save_stack(flags);
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}
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#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
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void kasan_enable_current(void)
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{
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current->kasan_depth++;
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}
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void kasan_disable_current(void)
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{
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current->kasan_depth--;
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}
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#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
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void __kasan_unpoison_range(const void *address, size_t size)
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{
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kasan_unpoison(address, size);
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}
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#if CONFIG_KASAN_STACK
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/* Unpoison the entire stack for a task. */
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void kasan_unpoison_task_stack(struct task_struct *task)
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{
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void *base = task_stack_page(task);
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kasan_unpoison(base, THREAD_SIZE);
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}
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/* Unpoison the stack for the current task beyond a watermark sp value. */
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asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
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{
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/*
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* Calculate the task stack base address. Avoid using 'current'
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* because this function is called by early resume code which hasn't
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* yet set up the percpu register (%gs).
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*/
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void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
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kasan_unpoison(base, watermark - base);
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}
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#endif /* CONFIG_KASAN_STACK */
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/*
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* Only allow cache merging when stack collection is disabled and no metadata
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* is present.
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*/
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slab_flags_t __kasan_never_merge(void)
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{
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if (kasan_stack_collection_enabled())
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return SLAB_KASAN;
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return 0;
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}
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void __kasan_alloc_pages(struct page *page, unsigned int order)
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{
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u8 tag;
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unsigned long i;
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if (unlikely(PageHighMem(page)))
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return;
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tag = kasan_random_tag();
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for (i = 0; i < (1 << order); i++)
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page_kasan_tag_set(page + i, tag);
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kasan_unpoison(page_address(page), PAGE_SIZE << order);
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}
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void __kasan_free_pages(struct page *page, unsigned int order)
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{
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if (likely(!PageHighMem(page)))
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kasan_poison(page_address(page), PAGE_SIZE << order,
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KASAN_FREE_PAGE);
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}
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/*
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* Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
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* For larger allocations larger redzones are used.
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*/
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static inline unsigned int optimal_redzone(unsigned int object_size)
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{
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return
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object_size <= 64 - 16 ? 16 :
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object_size <= 128 - 32 ? 32 :
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object_size <= 512 - 64 ? 64 :
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object_size <= 4096 - 128 ? 128 :
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object_size <= (1 << 14) - 256 ? 256 :
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object_size <= (1 << 15) - 512 ? 512 :
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object_size <= (1 << 16) - 1024 ? 1024 : 2048;
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}
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void __kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
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slab_flags_t *flags)
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{
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unsigned int ok_size;
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unsigned int optimal_size;
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/*
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* SLAB_KASAN is used to mark caches as ones that are sanitized by
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* KASAN. Currently this flag is used in two places:
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* 1. In slab_ksize() when calculating the size of the accessible
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* memory within the object.
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* 2. In slab_common.c to prevent merging of sanitized caches.
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*/
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*flags |= SLAB_KASAN;
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if (!kasan_stack_collection_enabled())
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return;
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ok_size = *size;
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/* Add alloc meta into redzone. */
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cache->kasan_info.alloc_meta_offset = *size;
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*size += sizeof(struct kasan_alloc_meta);
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/*
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* If alloc meta doesn't fit, don't add it.
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* This can only happen with SLAB, as it has KMALLOC_MAX_SIZE equal
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* to KMALLOC_MAX_CACHE_SIZE and doesn't fall back to page_alloc for
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* larger sizes.
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*/
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if (*size > KMALLOC_MAX_SIZE) {
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cache->kasan_info.alloc_meta_offset = 0;
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*size = ok_size;
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/* Continue, since free meta might still fit. */
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}
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/* Only the generic mode uses free meta or flexible redzones. */
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if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) {
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cache->kasan_info.free_meta_offset = KASAN_NO_FREE_META;
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return;
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}
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/*
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* Add free meta into redzone when it's not possible to store
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* it in the object. This is the case when:
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* 1. Object is SLAB_TYPESAFE_BY_RCU, which means that it can
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* be touched after it was freed, or
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* 2. Object has a constructor, which means it's expected to
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* retain its content until the next allocation, or
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* 3. Object is too small.
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* Otherwise cache->kasan_info.free_meta_offset = 0 is implied.
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*/
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if ((cache->flags & SLAB_TYPESAFE_BY_RCU) || cache->ctor ||
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cache->object_size < sizeof(struct kasan_free_meta)) {
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ok_size = *size;
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cache->kasan_info.free_meta_offset = *size;
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*size += sizeof(struct kasan_free_meta);
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/* If free meta doesn't fit, don't add it. */
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if (*size > KMALLOC_MAX_SIZE) {
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cache->kasan_info.free_meta_offset = KASAN_NO_FREE_META;
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*size = ok_size;
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}
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}
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/* Calculate size with optimal redzone. */
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optimal_size = cache->object_size + optimal_redzone(cache->object_size);
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/* Limit it with KMALLOC_MAX_SIZE (relevant for SLAB only). */
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if (optimal_size > KMALLOC_MAX_SIZE)
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optimal_size = KMALLOC_MAX_SIZE;
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/* Use optimal size if the size with added metas is not large enough. */
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if (*size < optimal_size)
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*size = optimal_size;
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}
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void __kasan_cache_create_kmalloc(struct kmem_cache *cache)
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{
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cache->kasan_info.is_kmalloc = true;
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}
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size_t __kasan_metadata_size(struct kmem_cache *cache)
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{
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if (!kasan_stack_collection_enabled())
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return 0;
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return (cache->kasan_info.alloc_meta_offset ?
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sizeof(struct kasan_alloc_meta) : 0) +
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(cache->kasan_info.free_meta_offset ?
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sizeof(struct kasan_free_meta) : 0);
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}
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struct kasan_alloc_meta *kasan_get_alloc_meta(struct kmem_cache *cache,
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const void *object)
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{
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if (!cache->kasan_info.alloc_meta_offset)
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return NULL;
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return kasan_reset_tag(object) + cache->kasan_info.alloc_meta_offset;
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}
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#ifdef CONFIG_KASAN_GENERIC
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struct kasan_free_meta *kasan_get_free_meta(struct kmem_cache *cache,
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const void *object)
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{
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BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32);
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if (cache->kasan_info.free_meta_offset == KASAN_NO_FREE_META)
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return NULL;
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return kasan_reset_tag(object) + cache->kasan_info.free_meta_offset;
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}
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#endif
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void __kasan_poison_slab(struct page *page)
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{
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unsigned long i;
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for (i = 0; i < compound_nr(page); i++)
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page_kasan_tag_reset(page + i);
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kasan_poison(page_address(page), page_size(page),
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KASAN_KMALLOC_REDZONE);
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}
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void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
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{
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kasan_unpoison(object, cache->object_size);
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}
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void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
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{
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kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
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KASAN_KMALLOC_REDZONE);
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}
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/*
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* This function assigns a tag to an object considering the following:
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* 1. A cache might have a constructor, which might save a pointer to a slab
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* object somewhere (e.g. in the object itself). We preassign a tag for
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* each object in caches with constructors during slab creation and reuse
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* the same tag each time a particular object is allocated.
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* 2. A cache might be SLAB_TYPESAFE_BY_RCU, which means objects can be
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* accessed after being freed. We preassign tags for objects in these
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* caches as well.
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* 3. For SLAB allocator we can't preassign tags randomly since the freelist
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* is stored as an array of indexes instead of a linked list. Assign tags
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* based on objects indexes, so that objects that are next to each other
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* get different tags.
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*/
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static inline u8 assign_tag(struct kmem_cache *cache,
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const void *object, bool init)
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{
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if (IS_ENABLED(CONFIG_KASAN_GENERIC))
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return 0xff;
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/*
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* If the cache neither has a constructor nor has SLAB_TYPESAFE_BY_RCU
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* set, assign a tag when the object is being allocated (init == false).
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*/
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if (!cache->ctor && !(cache->flags & SLAB_TYPESAFE_BY_RCU))
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return init ? KASAN_TAG_KERNEL : kasan_random_tag();
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/* For caches that either have a constructor or SLAB_TYPESAFE_BY_RCU: */
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#ifdef CONFIG_SLAB
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/* For SLAB assign tags based on the object index in the freelist. */
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return (u8)obj_to_index(cache, virt_to_page(object), (void *)object);
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#else
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/*
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* For SLUB assign a random tag during slab creation, otherwise reuse
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* the already assigned tag.
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*/
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return init ? kasan_random_tag() : get_tag(object);
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#endif
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}
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void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
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const void *object)
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{
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struct kasan_alloc_meta *alloc_meta;
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if (kasan_stack_collection_enabled()) {
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alloc_meta = kasan_get_alloc_meta(cache, object);
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if (alloc_meta)
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__memset(alloc_meta, 0, sizeof(*alloc_meta));
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}
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/* Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS */
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object = set_tag(object, assign_tag(cache, object, true));
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return (void *)object;
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}
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static inline bool ____kasan_slab_free(struct kmem_cache *cache,
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void *object, unsigned long ip, bool quarantine)
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{
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u8 tag;
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void *tagged_object;
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tag = get_tag(object);
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tagged_object = object;
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object = kasan_reset_tag(object);
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if (is_kfence_address(object))
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return false;
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if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) !=
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object)) {
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kasan_report_invalid_free(tagged_object, ip);
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return true;
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}
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/* RCU slabs could be legally used after free within the RCU period */
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if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
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return false;
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if (!kasan_byte_accessible(tagged_object)) {
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kasan_report_invalid_free(tagged_object, ip);
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return true;
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}
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kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
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KASAN_KMALLOC_FREE);
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if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine))
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return false;
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if (kasan_stack_collection_enabled())
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kasan_set_free_info(cache, object, tag);
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return kasan_quarantine_put(cache, object);
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}
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bool __kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
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{
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return ____kasan_slab_free(cache, object, ip, true);
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}
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static inline bool ____kasan_kfree_large(void *ptr, unsigned long ip)
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{
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if (ptr != page_address(virt_to_head_page(ptr))) {
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kasan_report_invalid_free(ptr, ip);
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return true;
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}
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if (!kasan_byte_accessible(ptr)) {
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kasan_report_invalid_free(ptr, ip);
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return true;
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}
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/*
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* The object will be poisoned by kasan_free_pages() or
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* kasan_slab_free_mempool().
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*/
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return false;
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}
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void __kasan_kfree_large(void *ptr, unsigned long ip)
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{
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____kasan_kfree_large(ptr, ip);
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}
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void __kasan_slab_free_mempool(void *ptr, unsigned long ip)
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{
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struct page *page;
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page = virt_to_head_page(ptr);
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/*
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* Even though this function is only called for kmem_cache_alloc and
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* kmalloc backed mempool allocations, those allocations can still be
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* !PageSlab() when the size provided to kmalloc is larger than
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* KMALLOC_MAX_SIZE, and kmalloc falls back onto page_alloc.
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*/
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if (unlikely(!PageSlab(page))) {
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if (____kasan_kfree_large(ptr, ip))
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return;
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kasan_poison(ptr, page_size(page), KASAN_FREE_PAGE);
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} else {
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____kasan_slab_free(page->slab_cache, ptr, ip, false);
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}
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}
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static void set_alloc_info(struct kmem_cache *cache, void *object,
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gfp_t flags, bool is_kmalloc)
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{
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struct kasan_alloc_meta *alloc_meta;
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/* Don't save alloc info for kmalloc caches in kasan_slab_alloc(). */
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if (cache->kasan_info.is_kmalloc && !is_kmalloc)
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return;
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alloc_meta = kasan_get_alloc_meta(cache, object);
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if (alloc_meta)
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kasan_set_track(&alloc_meta->alloc_track, flags);
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}
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void * __must_check __kasan_slab_alloc(struct kmem_cache *cache,
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void *object, gfp_t flags)
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{
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u8 tag;
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void *tagged_object;
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if (gfpflags_allow_blocking(flags))
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kasan_quarantine_reduce();
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if (unlikely(object == NULL))
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return NULL;
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if (is_kfence_address(object))
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return (void *)object;
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/*
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* Generate and assign random tag for tag-based modes.
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* Tag is ignored in set_tag() for the generic mode.
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*/
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tag = assign_tag(cache, object, false);
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tagged_object = set_tag(object, tag);
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/*
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* Unpoison the whole object.
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* For kmalloc() allocations, kasan_kmalloc() will do precise poisoning.
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*/
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kasan_unpoison(tagged_object, cache->object_size);
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/* Save alloc info (if possible) for non-kmalloc() allocations. */
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if (kasan_stack_collection_enabled())
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set_alloc_info(cache, (void *)object, flags, false);
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return tagged_object;
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}
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static inline void *____kasan_kmalloc(struct kmem_cache *cache,
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const void *object, size_t size, gfp_t flags)
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{
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unsigned long redzone_start;
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unsigned long redzone_end;
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if (gfpflags_allow_blocking(flags))
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kasan_quarantine_reduce();
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if (unlikely(object == NULL))
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return NULL;
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if (is_kfence_address(kasan_reset_tag(object)))
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return (void *)object;
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/*
|
|
* The object has already been unpoisoned by kasan_slab_alloc() for
|
|
* kmalloc() or by kasan_krealloc() for krealloc().
|
|
*/
|
|
|
|
/*
|
|
* The redzone has byte-level precision for the generic mode.
|
|
* Partially poison the last object granule to cover the unaligned
|
|
* part of the redzone.
|
|
*/
|
|
if (IS_ENABLED(CONFIG_KASAN_GENERIC))
|
|
kasan_poison_last_granule((void *)object, size);
|
|
|
|
/* Poison the aligned part of the redzone. */
|
|
redzone_start = round_up((unsigned long)(object + size),
|
|
KASAN_GRANULE_SIZE);
|
|
redzone_end = round_up((unsigned long)(object + cache->object_size),
|
|
KASAN_GRANULE_SIZE);
|
|
kasan_poison((void *)redzone_start, redzone_end - redzone_start,
|
|
KASAN_KMALLOC_REDZONE);
|
|
|
|
/*
|
|
* Save alloc info (if possible) for kmalloc() allocations.
|
|
* This also rewrites the alloc info when called from kasan_krealloc().
|
|
*/
|
|
if (kasan_stack_collection_enabled())
|
|
set_alloc_info(cache, (void *)object, flags, true);
|
|
|
|
/* Keep the tag that was set by kasan_slab_alloc(). */
|
|
return (void *)object;
|
|
}
|
|
|
|
void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object,
|
|
size_t size, gfp_t flags)
|
|
{
|
|
return ____kasan_kmalloc(cache, object, size, flags);
|
|
}
|
|
EXPORT_SYMBOL(__kasan_kmalloc);
|
|
|
|
void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size,
|
|
gfp_t flags)
|
|
{
|
|
unsigned long redzone_start;
|
|
unsigned long redzone_end;
|
|
|
|
if (gfpflags_allow_blocking(flags))
|
|
kasan_quarantine_reduce();
|
|
|
|
if (unlikely(ptr == NULL))
|
|
return NULL;
|
|
|
|
/*
|
|
* The object has already been unpoisoned by kasan_alloc_pages() for
|
|
* alloc_pages() or by kasan_krealloc() for krealloc().
|
|
*/
|
|
|
|
/*
|
|
* The redzone has byte-level precision for the generic mode.
|
|
* Partially poison the last object granule to cover the unaligned
|
|
* part of the redzone.
|
|
*/
|
|
if (IS_ENABLED(CONFIG_KASAN_GENERIC))
|
|
kasan_poison_last_granule(ptr, size);
|
|
|
|
/* Poison the aligned part of the redzone. */
|
|
redzone_start = round_up((unsigned long)(ptr + size),
|
|
KASAN_GRANULE_SIZE);
|
|
redzone_end = (unsigned long)ptr + page_size(virt_to_page(ptr));
|
|
kasan_poison((void *)redzone_start, redzone_end - redzone_start,
|
|
KASAN_PAGE_REDZONE);
|
|
|
|
return (void *)ptr;
|
|
}
|
|
|
|
void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flags)
|
|
{
|
|
struct page *page;
|
|
|
|
if (unlikely(object == ZERO_SIZE_PTR))
|
|
return (void *)object;
|
|
|
|
/*
|
|
* Unpoison the object's data.
|
|
* Part of it might already have been unpoisoned, but it's unknown
|
|
* how big that part is.
|
|
*/
|
|
kasan_unpoison(object, size);
|
|
|
|
page = virt_to_head_page(object);
|
|
|
|
/* Piggy-back on kmalloc() instrumentation to poison the redzone. */
|
|
if (unlikely(!PageSlab(page)))
|
|
return __kasan_kmalloc_large(object, size, flags);
|
|
else
|
|
return ____kasan_kmalloc(page->slab_cache, object, size, flags);
|
|
}
|
|
|
|
bool __kasan_check_byte(const void *address, unsigned long ip)
|
|
{
|
|
if (!kasan_byte_accessible(address)) {
|
|
kasan_report((unsigned long)address, 1, false, ip);
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|