1 files changed, 452 insertions, 0 deletions
diff --git a/mm/kasan/common.c b/mm/kasan/common.c
new file mode 100644
index 0000000000..256930da57
--- /dev/null
+++ b/mm/kasan/common.c
@@ -0,0 +1,452 @@
+// 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, 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 */
+
+bool __kasan_unpoison_pages(struct page *page, unsigned int order, bool init)
+{
+	u8 tag;
+	unsigned long i;
+
+	if (unlikely(PageHighMem(page)))
+		return false;
+
+	if (!kasan_sample_page_alloc(order))
+		return false;
+
+	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);
+
+	return true;
+}
+
+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_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() && !is_kmalloc_cache(cache))
+		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() && is_kmalloc_cache(cache))
+		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(address, 1, false, ip);
+		return false;
+	}
+	return true;
+}