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-rw-r--r--mm/kasan/common.c452
1 files changed, 452 insertions, 0 deletions
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
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+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file contains common KASAN 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 <andreyknvl@gmail.com>
+ */
+
+#include <linux/export.h>
+#include <linux/init.h>
+#include <linux/kasan.h>
+#include <linux/kernel.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/sched/task_stack.h>
+#include <linux/slab.h>
+#include <linux/stacktrace.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/bug.h>
+
+#include "kasan.h"
+#include "../slab.h"
+
+struct slab *kasan_addr_to_slab(const void *addr)
+{
+ if (virt_addr_valid(addr))
+ return virt_to_slab(addr);
+ return NULL;
+}
+
+depot_stack_handle_t kasan_save_stack(gfp_t flags, bool can_alloc)
+{
+ unsigned long entries[KASAN_STACK_DEPTH];
+ unsigned int nr_entries;
+
+ nr_entries = stack_trace_save(entries, ARRAY_SIZE(entries), 0);
+ return __stack_depot_save(entries, nr_entries, 0, flags, can_alloc);
+}
+
+void kasan_set_track(struct kasan_track *track, gfp_t flags)
+{
+ track->pid = current->pid;
+ track->stack = kasan_save_stack(flags, true);
+}
+
+#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
+void kasan_enable_current(void)
+{
+ current->kasan_depth++;
+}
+EXPORT_SYMBOL(kasan_enable_current);
+
+void kasan_disable_current(void)
+{
+ current->kasan_depth--;
+}
+EXPORT_SYMBOL(kasan_disable_current);
+
+#endif /* CONFIG_KASAN_GENERIC || CONFIG_KASAN_SW_TAGS */
+
+void __kasan_unpoison_range(const void *address, size_t size)
+{
+ kasan_unpoison(address, size, false);
+}
+
+#ifdef CONFIG_KASAN_STACK
+/* Unpoison the entire stack for a task. */
+void kasan_unpoison_task_stack(struct task_struct *task)
+{
+ void *base = task_stack_page(task);
+
+ kasan_unpoison(base, THREAD_SIZE, false);
+}
+
+/* Unpoison the stack for the current task beyond a watermark sp value. */
+asmlinkage void kasan_unpoison_task_stack_below(const void *watermark)
+{
+ /*
+ * Calculate the task stack base address. Avoid using 'current'
+ * because this function is called by early resume code which hasn't
+ * yet set up the percpu register (%gs).
+ */
+ void *base = (void *)((unsigned long)watermark & ~(THREAD_SIZE - 1));
+
+ kasan_unpoison(base, watermark - base, false);
+}
+#endif /* CONFIG_KASAN_STACK */
+
+void __kasan_unpoison_pages(struct page *page, unsigned int order, bool init)
+{
+ u8 tag;
+ unsigned long i;
+
+ if (unlikely(PageHighMem(page)))
+ return;
+
+ tag = kasan_random_tag();
+ kasan_unpoison(set_tag(page_address(page), tag),
+ PAGE_SIZE << order, init);
+ for (i = 0; i < (1 << order); i++)
+ page_kasan_tag_set(page + i, tag);
+}
+
+void __kasan_poison_pages(struct page *page, unsigned int order, bool init)
+{
+ if (likely(!PageHighMem(page)))
+ kasan_poison(page_address(page), PAGE_SIZE << order,
+ KASAN_PAGE_FREE, init);
+}
+
+void __kasan_cache_create_kmalloc(struct kmem_cache *cache)
+{
+ cache->kasan_info.is_kmalloc = true;
+}
+
+void __kasan_poison_slab(struct slab *slab)
+{
+ struct page *page = slab_page(slab);
+ unsigned long i;
+
+ for (i = 0; i < compound_nr(page); i++)
+ page_kasan_tag_reset(page + i);
+ kasan_poison(page_address(page), page_size(page),
+ KASAN_SLAB_REDZONE, false);
+}
+
+void __kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
+{
+ kasan_unpoison(object, cache->object_size, false);
+}
+
+void __kasan_poison_object_data(struct kmem_cache *cache, void *object)
+{
+ kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
+ KASAN_SLAB_REDZONE, false);
+}
+
+/*
+ * This function assigns a tag to an object considering the following:
+ * 1. A cache might have a constructor, which might save a pointer to a slab
+ * object somewhere (e.g. in the object itself). We preassign a tag for
+ * each object in caches with constructors during slab creation and reuse
+ * the same tag each time a particular object is allocated.
+ * 2. A cache might be SLAB_TYPESAFE_BY_RCU, which means objects can be
+ * accessed after being freed. We preassign tags for objects in these
+ * caches as well.
+ * 3. For SLAB allocator we can't preassign tags randomly since the freelist
+ * is stored as an array of indexes instead of a linked list. Assign tags
+ * based on objects indexes, so that objects that are next to each other
+ * get different tags.
+ */
+static inline u8 assign_tag(struct kmem_cache *cache,
+ const void *object, bool init)
+{
+ if (IS_ENABLED(CONFIG_KASAN_GENERIC))
+ return 0xff;
+
+ /*
+ * If the cache neither has a constructor nor has SLAB_TYPESAFE_BY_RCU
+ * set, assign a tag when the object is being allocated (init == false).
+ */
+ if (!cache->ctor && !(cache->flags & SLAB_TYPESAFE_BY_RCU))
+ return init ? KASAN_TAG_KERNEL : kasan_random_tag();
+
+ /* For caches that either have a constructor or SLAB_TYPESAFE_BY_RCU: */
+#ifdef CONFIG_SLAB
+ /* For SLAB assign tags based on the object index in the freelist. */
+ return (u8)obj_to_index(cache, virt_to_slab(object), (void *)object);
+#else
+ /*
+ * For SLUB assign a random tag during slab creation, otherwise reuse
+ * the already assigned tag.
+ */
+ return init ? kasan_random_tag() : get_tag(object);
+#endif
+}
+
+void * __must_check __kasan_init_slab_obj(struct kmem_cache *cache,
+ const void *object)
+{
+ /* Initialize per-object metadata if it is present. */
+ if (kasan_requires_meta())
+ kasan_init_object_meta(cache, object);
+
+ /* Tag is ignored in set_tag() without CONFIG_KASAN_SW/HW_TAGS */
+ object = set_tag(object, assign_tag(cache, object, true));
+
+ return (void *)object;
+}
+
+static inline bool ____kasan_slab_free(struct kmem_cache *cache, void *object,
+ unsigned long ip, bool quarantine, bool init)
+{
+ void *tagged_object;
+
+ if (!kasan_arch_is_ready())
+ return false;
+
+ tagged_object = object;
+ object = kasan_reset_tag(object);
+
+ if (is_kfence_address(object))
+ return false;
+
+ if (unlikely(nearest_obj(cache, virt_to_slab(object), object) !=
+ object)) {
+ kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_INVALID_FREE);
+ return true;
+ }
+
+ /* RCU slabs could be legally used after free within the RCU period */
+ if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
+ return false;
+
+ if (!kasan_byte_accessible(tagged_object)) {
+ kasan_report_invalid_free(tagged_object, ip, KASAN_REPORT_DOUBLE_FREE);
+ return true;
+ }
+
+ kasan_poison(object, round_up(cache->object_size, KASAN_GRANULE_SIZE),
+ KASAN_SLAB_FREE, init);
+
+ if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine))
+ return false;
+
+ if (kasan_stack_collection_enabled())
+ kasan_save_free_info(cache, tagged_object);
+
+ return kasan_quarantine_put(cache, object);
+}
+
+bool __kasan_slab_free(struct kmem_cache *cache, void *object,
+ unsigned long ip, bool init)
+{
+ return ____kasan_slab_free(cache, object, ip, true, init);
+}
+
+static inline bool ____kasan_kfree_large(void *ptr, unsigned long ip)
+{
+ if (!kasan_arch_is_ready())
+ return false;
+
+ if (ptr != page_address(virt_to_head_page(ptr))) {
+ kasan_report_invalid_free(ptr, ip, KASAN_REPORT_INVALID_FREE);
+ return true;
+ }
+
+ if (!kasan_byte_accessible(ptr)) {
+ kasan_report_invalid_free(ptr, ip, KASAN_REPORT_DOUBLE_FREE);
+ return true;
+ }
+
+ /*
+ * The object will be poisoned by kasan_poison_pages() or
+ * kasan_slab_free_mempool().
+ */
+
+ return false;
+}
+
+void __kasan_kfree_large(void *ptr, unsigned long ip)
+{
+ ____kasan_kfree_large(ptr, ip);
+}
+
+void __kasan_slab_free_mempool(void *ptr, unsigned long ip)
+{
+ struct folio *folio;
+
+ folio = virt_to_folio(ptr);
+
+ /*
+ * Even though this function is only called for kmem_cache_alloc and
+ * kmalloc backed mempool allocations, those allocations can still be
+ * !PageSlab() when the size provided to kmalloc is larger than
+ * KMALLOC_MAX_SIZE, and kmalloc falls back onto page_alloc.
+ */
+ if (unlikely(!folio_test_slab(folio))) {
+ if (____kasan_kfree_large(ptr, ip))
+ return;
+ kasan_poison(ptr, folio_size(folio), KASAN_PAGE_FREE, false);
+ } else {
+ struct slab *slab = folio_slab(folio);
+
+ ____kasan_slab_free(slab->slab_cache, ptr, ip, false, false);
+ }
+}
+
+void * __must_check __kasan_slab_alloc(struct kmem_cache *cache,
+ void *object, gfp_t flags, bool init)
+{
+ u8 tag;
+ void *tagged_object;
+
+ if (gfpflags_allow_blocking(flags))
+ kasan_quarantine_reduce();
+
+ if (unlikely(object == NULL))
+ return NULL;
+
+ if (is_kfence_address(object))
+ return (void *)object;
+
+ /*
+ * Generate and assign random tag for tag-based modes.
+ * Tag is ignored in set_tag() for the generic mode.
+ */
+ tag = assign_tag(cache, object, false);
+ tagged_object = set_tag(object, tag);
+
+ /*
+ * Unpoison the whole object.
+ * For kmalloc() allocations, kasan_kmalloc() will do precise poisoning.
+ */
+ kasan_unpoison(tagged_object, cache->object_size, init);
+
+ /* Save alloc info (if possible) for non-kmalloc() allocations. */
+ if (kasan_stack_collection_enabled() && !cache->kasan_info.is_kmalloc)
+ kasan_save_alloc_info(cache, tagged_object, flags);
+
+ return tagged_object;
+}
+
+static inline 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 (gfpflags_allow_blocking(flags))
+ kasan_quarantine_reduce();
+
+ if (unlikely(object == NULL))
+ return NULL;
+
+ if (is_kfence_address(kasan_reset_tag(object)))
+ return (void *)object;
+
+ /*
+ * 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_SLAB_REDZONE, false);
+
+ /*
+ * Save alloc info (if possible) for kmalloc() allocations.
+ * This also rewrites the alloc info when called from kasan_krealloc().
+ */
+ if (kasan_stack_collection_enabled() && cache->kasan_info.is_kmalloc)
+ kasan_save_alloc_info(cache, (void *)object, flags);
+
+ /* 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_unpoison_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, false);
+
+ return (void *)ptr;
+}
+
+void * __must_check __kasan_krealloc(const void *object, size_t size, gfp_t flags)
+{
+ struct slab *slab;
+
+ 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, false);
+
+ slab = virt_to_slab(object);
+
+ /* Piggy-back on kmalloc() instrumentation to poison the redzone. */
+ if (unlikely(!slab))
+ return __kasan_kmalloc_large(object, size, flags);
+ else
+ return ____kasan_kmalloc(slab->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;
+}