mirror of
https://github.com/torvalds/linux
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550 lines
14 KiB
C
550 lines
14 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/clock.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/stackdepot.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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struct slab *kasan_addr_to_slab(const void *addr)
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{
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if (virt_addr_valid(addr))
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return virt_to_slab(addr);
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return NULL;
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}
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depot_stack_handle_t kasan_save_stack(gfp_t flags, depot_flags_t depot_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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return stack_depot_save_flags(entries, nr_entries, flags, depot_flags);
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}
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void kasan_set_track(struct kasan_track *track, depot_stack_handle_t stack)
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{
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#ifdef CONFIG_KASAN_EXTRA_INFO
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u32 cpu = raw_smp_processor_id();
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u64 ts_nsec = local_clock();
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track->cpu = cpu;
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track->timestamp = ts_nsec >> 9;
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#endif /* CONFIG_KASAN_EXTRA_INFO */
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track->pid = current->pid;
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track->stack = stack;
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}
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void kasan_save_track(struct kasan_track *track, gfp_t flags)
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{
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depot_stack_handle_t stack;
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stack = kasan_save_stack(flags, STACK_DEPOT_FLAG_CAN_ALLOC);
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kasan_set_track(track, stack);
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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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EXPORT_SYMBOL(kasan_enable_current);
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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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EXPORT_SYMBOL(kasan_disable_current);
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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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if (is_kfence_address(address))
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return;
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kasan_unpoison(address, size, false);
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}
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#ifdef 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, false);
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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, false);
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}
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#endif /* CONFIG_KASAN_STACK */
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bool __kasan_unpoison_pages(struct page *page, unsigned int order, bool init)
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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 false;
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if (!kasan_sample_page_alloc(order))
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return false;
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tag = kasan_random_tag();
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kasan_unpoison(set_tag(page_address(page), tag),
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PAGE_SIZE << order, init);
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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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return true;
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}
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void __kasan_poison_pages(struct page *page, unsigned int order, bool init)
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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_PAGE_FREE, init);
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}
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void __kasan_poison_slab(struct slab *slab)
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{
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struct page *page = slab_page(slab);
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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_SLAB_REDZONE, false);
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}
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void __kasan_unpoison_new_object(struct kmem_cache *cache, void *object)
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{
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kasan_unpoison(object, cache->object_size, false);
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}
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void __kasan_poison_new_object(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_SLAB_REDZONE, false);
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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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*/
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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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/*
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* For caches that either have a constructor or SLAB_TYPESAFE_BY_RCU,
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* 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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}
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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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/* Initialize per-object metadata if it is present. */
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if (kasan_requires_meta())
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kasan_init_object_meta(cache, object);
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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 poison_slab_object(struct kmem_cache *cache, void *object,
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unsigned long ip, bool init)
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{
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void *tagged_object;
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if (!kasan_arch_is_ready())
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return false;
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tagged_object = object;
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object = kasan_reset_tag(object);
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if (unlikely(nearest_obj(cache, virt_to_slab(object), object) != object)) {
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kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_INVALID_FREE);
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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, KASAN_REPORT_DOUBLE_FREE);
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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_SLAB_FREE, init);
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if (kasan_stack_collection_enabled())
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kasan_save_free_info(cache, tagged_object);
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return false;
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}
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bool __kasan_slab_free(struct kmem_cache *cache, void *object,
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unsigned long ip, bool init)
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{
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if (is_kfence_address(object))
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return false;
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/*
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* If the object is buggy, do not let slab put the object onto the
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* freelist. The object will thus never be allocated again and its
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* metadata will never get released.
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*/
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if (poison_slab_object(cache, object, ip, init))
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return true;
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/*
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* If the object is put into quarantine, do not let slab put the object
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* onto the freelist for now. The object's metadata is kept until the
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* object gets evicted from quarantine.
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*/
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if (kasan_quarantine_put(cache, object))
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return true;
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/*
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* Note: Keep per-object metadata to allow KASAN print stack traces for
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* use-after-free-before-realloc bugs.
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*/
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/* Let slab put the object onto the freelist. */
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return false;
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}
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static inline bool check_page_allocation(void *ptr, unsigned long ip)
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{
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if (!kasan_arch_is_ready())
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return false;
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if (ptr != page_address(virt_to_head_page(ptr))) {
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kasan_report_invalid_free(ptr, ip, KASAN_REPORT_INVALID_FREE);
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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, KASAN_REPORT_DOUBLE_FREE);
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return true;
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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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check_page_allocation(ptr, ip);
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/* The object will be poisoned by kasan_poison_pages(). */
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}
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static inline void unpoison_slab_object(struct kmem_cache *cache, void *object,
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gfp_t flags, bool init)
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{
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/*
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* Unpoison the whole object. For kmalloc() allocations,
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* poison_kmalloc_redzone() will do precise poisoning.
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*/
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kasan_unpoison(object, cache->object_size, init);
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/* Save alloc info (if possible) for non-kmalloc() allocations. */
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if (kasan_stack_collection_enabled() && !is_kmalloc_cache(cache))
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kasan_save_alloc_info(cache, object, 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, bool init)
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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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/* Unpoison the object and save alloc info for non-kmalloc() allocations. */
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unpoison_slab_object(cache, tagged_object, flags, init);
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return tagged_object;
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}
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static inline void poison_kmalloc_redzone(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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/*
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* The redzone has byte-level precision for the generic mode.
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* Partially poison the last object granule to cover the unaligned
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* part of the redzone.
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*/
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if (IS_ENABLED(CONFIG_KASAN_GENERIC))
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kasan_poison_last_granule((void *)object, size);
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/* Poison the aligned part of the redzone. */
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redzone_start = round_up((unsigned long)(object + size),
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KASAN_GRANULE_SIZE);
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redzone_end = round_up((unsigned long)(object + cache->object_size),
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KASAN_GRANULE_SIZE);
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kasan_poison((void *)redzone_start, redzone_end - redzone_start,
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KASAN_SLAB_REDZONE, false);
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/*
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* Save alloc info (if possible) for kmalloc() allocations.
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* This also rewrites the alloc info when called from kasan_krealloc().
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*/
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if (kasan_stack_collection_enabled() && is_kmalloc_cache(cache))
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kasan_save_alloc_info(cache, (void *)object, flags);
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}
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void * __must_check __kasan_kmalloc(struct kmem_cache *cache, const void *object,
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size_t size, gfp_t flags)
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{
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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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/* The object has already been unpoisoned by kasan_slab_alloc(). */
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poison_kmalloc_redzone(cache, object, size, flags);
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/* Keep the tag that was set by kasan_slab_alloc(). */
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return (void *)object;
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}
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EXPORT_SYMBOL(__kasan_kmalloc);
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static inline void poison_kmalloc_large_redzone(const void *ptr, size_t size,
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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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/*
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* The redzone has byte-level precision for the generic mode.
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* Partially poison the last object granule to cover the unaligned
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* part of the redzone.
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*/
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if (IS_ENABLED(CONFIG_KASAN_GENERIC))
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kasan_poison_last_granule(ptr, size);
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/* Poison the aligned part of the redzone. */
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redzone_start = round_up((unsigned long)(ptr + size), KASAN_GRANULE_SIZE);
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redzone_end = (unsigned long)ptr + page_size(virt_to_page(ptr));
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kasan_poison((void *)redzone_start, redzone_end - redzone_start,
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KASAN_PAGE_REDZONE, false);
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}
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void * __must_check __kasan_kmalloc_large(const void *ptr, size_t size,
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gfp_t flags)
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{
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if (gfpflags_allow_blocking(flags))
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kasan_quarantine_reduce();
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if (unlikely(ptr == NULL))
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return NULL;
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/* The object has already been unpoisoned by kasan_unpoison_pages(). */
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poison_kmalloc_large_redzone(ptr, size, flags);
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/* Keep the tag that was set by alloc_pages(). */
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return (void *)ptr;
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}
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void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flags)
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{
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struct slab *slab;
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if (gfpflags_allow_blocking(flags))
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kasan_quarantine_reduce();
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if (unlikely(object == ZERO_SIZE_PTR))
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return (void *)object;
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if (is_kfence_address(object))
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return (void *)object;
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/*
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* Unpoison the object's data.
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* Part of it might already have been unpoisoned, but it's unknown
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* how big that part is.
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*/
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kasan_unpoison(object, size, false);
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slab = virt_to_slab(object);
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/* Piggy-back on kmalloc() instrumentation to poison the redzone. */
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if (unlikely(!slab))
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poison_kmalloc_large_redzone(object, size, flags);
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else
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poison_kmalloc_redzone(slab->slab_cache, object, size, flags);
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return (void *)object;
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}
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bool __kasan_mempool_poison_pages(struct page *page, unsigned int order,
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unsigned long ip)
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{
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unsigned long *ptr;
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if (unlikely(PageHighMem(page)))
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return true;
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/* Bail out if allocation was excluded due to sampling. */
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if (!IS_ENABLED(CONFIG_KASAN_GENERIC) &&
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page_kasan_tag(page) == KASAN_TAG_KERNEL)
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return true;
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ptr = page_address(page);
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if (check_page_allocation(ptr, ip))
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return false;
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kasan_poison(ptr, PAGE_SIZE << order, KASAN_PAGE_FREE, false);
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return true;
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}
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void __kasan_mempool_unpoison_pages(struct page *page, unsigned int order,
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unsigned long ip)
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{
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__kasan_unpoison_pages(page, order, false);
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}
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bool __kasan_mempool_poison_object(void *ptr, unsigned long ip)
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{
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struct folio *folio = virt_to_folio(ptr);
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struct slab *slab;
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/*
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* This function can be called for large kmalloc allocation that get
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* their memory from page_alloc. Thus, the folio might not be a slab.
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*/
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if (unlikely(!folio_test_slab(folio))) {
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if (check_page_allocation(ptr, ip))
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return false;
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kasan_poison(ptr, folio_size(folio), KASAN_PAGE_FREE, false);
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return true;
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}
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if (is_kfence_address(ptr))
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return false;
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slab = folio_slab(folio);
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return !poison_slab_object(slab->slab_cache, ptr, ip, false);
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}
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void __kasan_mempool_unpoison_object(void *ptr, size_t size, unsigned long ip)
|
|
{
|
|
struct slab *slab;
|
|
gfp_t flags = 0; /* Might be executing under a lock. */
|
|
|
|
slab = virt_to_slab(ptr);
|
|
|
|
/*
|
|
* This function can be called for large kmalloc allocation that get
|
|
* their memory from page_alloc.
|
|
*/
|
|
if (unlikely(!slab)) {
|
|
kasan_unpoison(ptr, size, false);
|
|
poison_kmalloc_large_redzone(ptr, size, flags);
|
|
return;
|
|
}
|
|
|
|
if (is_kfence_address(ptr))
|
|
return;
|
|
|
|
/* Unpoison the object and save alloc info for non-kmalloc() allocations. */
|
|
unpoison_slab_object(slab->slab_cache, ptr, size, flags);
|
|
|
|
/* Poison the redzone and save alloc info for kmalloc() allocations. */
|
|
if (is_kmalloc_cache(slab->slab_cache))
|
|
poison_kmalloc_redzone(slab->slab_cache, ptr, size, flags);
|
|
}
|
|
|
|
bool __kasan_check_byte(const void *address, unsigned long ip)
|
|
{
|
|
if (!kasan_byte_accessible(address)) {
|
|
kasan_report(address, 1, false, ip);
|
|
return false;
|
|
}
|
|
return true;
|
|
}
|