1 files changed, 697 insertions, 0 deletions

diff --git a/mm/kasan/common.c b/mm/kasan/common.c
new file mode 100644
index 000000000000..03d5d1374ca7
--- /dev/null
+++ b/mm/kasan/common.c
@@ -0,0 +1,697 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * This file contains common generic and tag-based 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>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ *
+ */
+
+#include <linux/export.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/kasan.h>
+#include <linux/kernel.h>
+#include <linux/kmemleak.h>
+#include <linux/linkage.h>
+#include <linux/memblock.h>
+#include <linux/memory.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/printk.h>
+#include <linux/sched.h>
+#include <linux/sched/task_stack.h>
+#include <linux/slab.h>
+#include <linux/stacktrace.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/vmalloc.h>
+#include <linux/bug.h>
+
+#include "kasan.h"
+#include "../slab.h"
+
+static inline int in_irqentry_text(unsigned long ptr)
+{
+        return (ptr >= (unsigned long)&__irqentry_text_start &&
+                ptr < (unsigned long)&__irqentry_text_end) ||
+                (ptr >= (unsigned long)&__softirqentry_text_start &&
+                 ptr < (unsigned long)&__softirqentry_text_end);
+}
+
+static inline void filter_irq_stacks(struct stack_trace *trace)
+{
+        int i;
+
+        if (!trace->nr_entries)
+                return;
+        for (i = 0; i < trace->nr_entries; i++)
+                if (in_irqentry_text(trace->entries[i])) {
+                        /* Include the irqentry function into the stack. */
+                        trace->nr_entries = i + 1;
+                        break;
+                }
+}
+
+static inline depot_stack_handle_t save_stack(gfp_t flags)
+{
+        unsigned long entries[KASAN_STACK_DEPTH];
+        struct stack_trace trace = {
+                .nr_entries = 0,
+                .entries = entries,
+                .max_entries = KASAN_STACK_DEPTH,
+                .skip = 0
+        };
+
+        save_stack_trace(&trace);
+        filter_irq_stacks(&trace);
+        if (trace.nr_entries != 0 &&
+            trace.entries[trace.nr_entries-1] == ULONG_MAX)
+                trace.nr_entries--;
+
+        return depot_save_stack(&trace, flags);
+}
+
+static inline void set_track(struct kasan_track *track, gfp_t flags)
+{
+        track->pid = current->pid;
+        track->stack = save_stack(flags);
+}
+
+void kasan_enable_current(void)
+{
+        current->kasan_depth++;
+}
+
+void kasan_disable_current(void)
+{
+        current->kasan_depth--;
+}
+
+void kasan_check_read(const volatile void *p, unsigned int size)
+{
+        check_memory_region((unsigned long)p, size, false, _RET_IP_);
+}
+EXPORT_SYMBOL(kasan_check_read);
+
+void kasan_check_write(const volatile void *p, unsigned int size)
+{
+        check_memory_region((unsigned long)p, size, true, _RET_IP_);
+}
+EXPORT_SYMBOL(kasan_check_write);
+
+#undef memset
+void *memset(void *addr, int c, size_t len)
+{
+        check_memory_region((unsigned long)addr, len, true, _RET_IP_);
+
+        return __memset(addr, c, len);
+}
+
+#undef memmove
+void *memmove(void *dest, const void *src, size_t len)
+{
+        check_memory_region((unsigned long)src, len, false, _RET_IP_);
+        check_memory_region((unsigned long)dest, len, true, _RET_IP_);
+
+        return __memmove(dest, src, len);
+}
+
+#undef memcpy
+void *memcpy(void *dest, const void *src, size_t len)
+{
+        check_memory_region((unsigned long)src, len, false, _RET_IP_);
+        check_memory_region((unsigned long)dest, len, true, _RET_IP_);
+
+        return __memcpy(dest, src, len);
+}
+
+/*
+ * Poisons the shadow memory for 'size' bytes starting from 'addr'.
+ * Memory addresses should be aligned to KASAN_SHADOW_SCALE_SIZE.
+ */
+void kasan_poison_shadow(const void *address, size_t size, u8 value)
+{
+        void *shadow_start, *shadow_end;
+
+        /*
+         * Perform shadow offset calculation based on untagged address, as
+         * some of the callers (e.g. kasan_poison_object_data) pass tagged
+         * addresses to this function.
+         */
+        address = reset_tag(address);
+
+        shadow_start = kasan_mem_to_shadow(address);
+        shadow_end = kasan_mem_to_shadow(address + size);
+
+        __memset(shadow_start, value, shadow_end - shadow_start);
+}
+
+void kasan_unpoison_shadow(const void *address, size_t size)
+{
+        u8 tag = get_tag(address);
+
+        /*
+         * Perform shadow offset calculation based on untagged address, as
+         * some of the callers (e.g. kasan_unpoison_object_data) pass tagged
+         * addresses to this function.
+         */
+        address = reset_tag(address);
+
+        kasan_poison_shadow(address, size, tag);
+
+        if (size & KASAN_SHADOW_MASK) {
+                u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size);
+
+                if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
+                        *shadow = tag;
+                else
+                        *shadow = size & KASAN_SHADOW_MASK;
+        }
+}
+
+static void __kasan_unpoison_stack(struct task_struct *task, const void *sp)
+{
+        void *base = task_stack_page(task);
+        size_t size = sp - base;
+
+        kasan_unpoison_shadow(base, size);
+}
+
+/* Unpoison the entire stack for a task. */
+void kasan_unpoison_task_stack(struct task_struct *task)
+{
+        __kasan_unpoison_stack(task, task_stack_page(task) + THREAD_SIZE);
+}
+
+/* Unpoison the stack for the current task beyond a watermark sp value. */
+asmlinkage void kasan_unpoison_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_shadow(base, watermark - base);
+}
+
+/*
+ * Clear all poison for the region between the current SP and a provided
+ * watermark value, as is sometimes required prior to hand-crafted asm function
+ * returns in the middle of functions.
+ */
+void kasan_unpoison_stack_above_sp_to(const void *watermark)
+{
+        const void *sp = __builtin_frame_address(0);
+        size_t size = watermark - sp;
+
+        if (WARN_ON(sp > watermark))
+                return;
+        kasan_unpoison_shadow(sp, size);
+}
+
+void kasan_alloc_pages(struct page *page, unsigned int order)
+{
+        u8 tag;
+        unsigned long i;
+
+        if (unlikely(PageHighMem(page)))
+                return;
+
+        tag = random_tag();
+        for (i = 0; i < (1 << order); i++)
+                page_kasan_tag_set(page + i, tag);
+        kasan_unpoison_shadow(page_address(page), PAGE_SIZE << order);
+}
+
+void kasan_free_pages(struct page *page, unsigned int order)
+{
+        if (likely(!PageHighMem(page)))
+                kasan_poison_shadow(page_address(page),
+                                PAGE_SIZE << order,
+                                KASAN_FREE_PAGE);
+}
+
+/*
+ * Adaptive redzone policy taken from the userspace AddressSanitizer runtime.
+ * For larger allocations larger redzones are used.
+ */
+static inline unsigned int optimal_redzone(unsigned int object_size)
+{
+        if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
+                return 0;
+
+        return
+                object_size <= 64        - 16   ? 16 :
+                object_size <= 128       - 32   ? 32 :
+                object_size <= 512       - 64   ? 64 :
+                object_size <= 4096      - 128  ? 128 :
+                object_size <= (1 << 14) - 256  ? 256 :
+                object_size <= (1 << 15) - 512  ? 512 :
+                object_size <= (1 << 16) - 1024 ? 1024 : 2048;
+}
+
+void kasan_cache_create(struct kmem_cache *cache, unsigned int *size,
+                        slab_flags_t *flags)
+{
+        unsigned int orig_size = *size;
+        unsigned int redzone_size;
+        int redzone_adjust;
+
+        /* Add alloc meta. */
+        cache->kasan_info.alloc_meta_offset = *size;
+        *size += sizeof(struct kasan_alloc_meta);
+
+        /* Add free meta. */
+        if (IS_ENABLED(CONFIG_KASAN_GENERIC) &&
+            (cache->flags & SLAB_TYPESAFE_BY_RCU || cache->ctor ||
+             cache->object_size < sizeof(struct kasan_free_meta))) {
+                cache->kasan_info.free_meta_offset = *size;
+                *size += sizeof(struct kasan_free_meta);
+        }
+
+        redzone_size = optimal_redzone(cache->object_size);
+        redzone_adjust = redzone_size - (*size - cache->object_size);
+        if (redzone_adjust > 0)
+                *size += redzone_adjust;
+
+        *size = min_t(unsigned int, KMALLOC_MAX_SIZE,
+                        max(*size, cache->object_size + redzone_size));
+
+        /*
+         * If the metadata doesn't fit, don't enable KASAN at all.
+         */
+        if (*size <= cache->kasan_info.alloc_meta_offset ||
+                        *size <= cache->kasan_info.free_meta_offset) {
+                cache->kasan_info.alloc_meta_offset = 0;
+                cache->kasan_info.free_meta_offset = 0;
+                *size = orig_size;
+                return;
+        }
+
+        cache->align = round_up(cache->align, KASAN_SHADOW_SCALE_SIZE);
+
+        *flags |= SLAB_KASAN;
+}
+
+size_t kasan_metadata_size(struct kmem_cache *cache)
+{
+        return (cache->kasan_info.alloc_meta_offset ?
+                sizeof(struct kasan_alloc_meta) : 0) +
+                (cache->kasan_info.free_meta_offset ?
+                sizeof(struct kasan_free_meta) : 0);
+}
+
+struct kasan_alloc_meta *get_alloc_info(struct kmem_cache *cache,
+                                        const void *object)
+{
+        BUILD_BUG_ON(sizeof(struct kasan_alloc_meta) > 32);
+        return (void *)object + cache->kasan_info.alloc_meta_offset;
+}
+
+struct kasan_free_meta *get_free_info(struct kmem_cache *cache,
+                                      const void *object)
+{
+        BUILD_BUG_ON(sizeof(struct kasan_free_meta) > 32);
+        return (void *)object + cache->kasan_info.free_meta_offset;
+}
+
+void kasan_poison_slab(struct page *page)
+{
+        unsigned long i;
+
+        for (i = 0; i < (1 << compound_order(page)); i++)
+                page_kasan_tag_reset(page + i);
+        kasan_poison_shadow(page_address(page),
+                        PAGE_SIZE << compound_order(page),
+                        KASAN_KMALLOC_REDZONE);
+}
+
+void kasan_unpoison_object_data(struct kmem_cache *cache, void *object)
+{
+        kasan_unpoison_shadow(object, cache->object_size);
+}
+
+void kasan_poison_object_data(struct kmem_cache *cache, void *object)
+{
+        kasan_poison_shadow(object,
+                        round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE),
+                        KASAN_KMALLOC_REDZONE);
+}
+
+/*
+ * Since it's desirable to only call object contructors once during slab
+ * allocation, we preassign tags to all such objects. Also preassign tags for
+ * SLAB_TYPESAFE_BY_RCU slabs to avoid use-after-free reports.
+ * 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.
+ * After a tag is assigned, the object always gets allocated with the same tag.
+ * The reason is that we can't change tags for objects with constructors on
+ * reallocation (even for non-SLAB_TYPESAFE_BY_RCU), because the constructor
+ * code can save the pointer to the object somewhere (e.g. in the object
+ * itself). Then if we retag it, the old saved pointer will become invalid.
+ */
+static u8 assign_tag(struct kmem_cache *cache, const void *object, bool new)
+{
+        if (!cache->ctor && !(cache->flags & SLAB_TYPESAFE_BY_RCU))
+                return new ? KASAN_TAG_KERNEL : random_tag();
+
+#ifdef CONFIG_SLAB
+        return (u8)obj_to_index(cache, virt_to_page(object), (void *)object);
+#else
+        return new ? random_tag() : get_tag(object);
+#endif
+}
+
+void * __must_check kasan_init_slab_obj(struct kmem_cache *cache,
+                                                const void *object)
+{
+        struct kasan_alloc_meta *alloc_info;
+
+        if (!(cache->flags & SLAB_KASAN))
+                return (void *)object;
+
+        alloc_info = get_alloc_info(cache, object);
+        __memset(alloc_info, 0, sizeof(*alloc_info));
+
+        if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
+                object = set_tag(object, assign_tag(cache, object, true));
+
+        return (void *)object;
+}
+
+void * __must_check kasan_slab_alloc(struct kmem_cache *cache, void *object,
+                                        gfp_t flags)
+{
+        return kasan_kmalloc(cache, object, cache->object_size, flags);
+}
+
+static inline bool shadow_invalid(u8 tag, s8 shadow_byte)
+{
+        if (IS_ENABLED(CONFIG_KASAN_GENERIC))
+                return shadow_byte < 0 ||
+                        shadow_byte >= KASAN_SHADOW_SCALE_SIZE;
+        else
+                return tag != (u8)shadow_byte;
+}
+
+static bool __kasan_slab_free(struct kmem_cache *cache, void *object,
+                              unsigned long ip, bool quarantine)
+{
+        s8 shadow_byte;
+        u8 tag;
+        void *tagged_object;
+        unsigned long rounded_up_size;
+
+        tag = get_tag(object);
+        tagged_object = object;
+        object = reset_tag(object);
+
+        if (unlikely(nearest_obj(cache, virt_to_head_page(object), object) !=
+            object)) {
+                kasan_report_invalid_free(tagged_object, ip);
+                return true;
+        }
+
+        /* RCU slabs could be legally used after free within the RCU period */
+        if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU))
+                return false;
+
+        shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(object));
+        if (shadow_invalid(tag, shadow_byte)) {
+                kasan_report_invalid_free(tagged_object, ip);
+                return true;
+        }
+
+        rounded_up_size = round_up(cache->object_size, KASAN_SHADOW_SCALE_SIZE);
+        kasan_poison_shadow(object, rounded_up_size, KASAN_KMALLOC_FREE);
+
+        if ((IS_ENABLED(CONFIG_KASAN_GENERIC) && !quarantine) ||
+                        unlikely(!(cache->flags & SLAB_KASAN)))
+                return false;
+
+        set_track(&get_alloc_info(cache, object)->free_track, GFP_NOWAIT);
+        quarantine_put(get_free_info(cache, object), cache);
+
+        return IS_ENABLED(CONFIG_KASAN_GENERIC);
+}
+
+bool kasan_slab_free(struct kmem_cache *cache, void *object, unsigned long ip)
+{
+        return __kasan_slab_free(cache, object, ip, true);
+}
+
+void * __must_check kasan_kmalloc(struct kmem_cache *cache, const void *object,
+                                        size_t size, gfp_t flags)
+{
+        unsigned long redzone_start;
+        unsigned long redzone_end;
+        u8 tag;
+
+        if (gfpflags_allow_blocking(flags))
+                quarantine_reduce();
+
+        if (unlikely(object == NULL))
+                return NULL;
+
+        redzone_start = round_up((unsigned long)(object + size),
+                                KASAN_SHADOW_SCALE_SIZE);
+        redzone_end = round_up((unsigned long)object + cache->object_size,
+                                KASAN_SHADOW_SCALE_SIZE);
+
+        if (IS_ENABLED(CONFIG_KASAN_SW_TAGS))
+                tag = assign_tag(cache, object, false);
+
+        /* Tag is ignored in set_tag without CONFIG_KASAN_SW_TAGS */
+        kasan_unpoison_shadow(set_tag(object, tag), size);
+        kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
+                KASAN_KMALLOC_REDZONE);
+
+        if (cache->flags & SLAB_KASAN)
+                set_track(&get_alloc_info(cache, object)->alloc_track, flags);
+
+        return set_tag(object, tag);
+}
+EXPORT_SYMBOL(kasan_kmalloc);
+
+void * __must_check kasan_kmalloc_large(const void *ptr, size_t size,
+                                                gfp_t flags)
+{
+        struct page *page;
+        unsigned long redzone_start;
+        unsigned long redzone_end;
+
+        if (gfpflags_allow_blocking(flags))
+                quarantine_reduce();
+
+        if (unlikely(ptr == NULL))
+                return NULL;
+
+        page = virt_to_page(ptr);
+        redzone_start = round_up((unsigned long)(ptr + size),
+                                KASAN_SHADOW_SCALE_SIZE);
+        redzone_end = (unsigned long)ptr + (PAGE_SIZE << compound_order(page));
+
+        kasan_unpoison_shadow(ptr, size);
+        kasan_poison_shadow((void *)redzone_start, redzone_end - redzone_start,
+                KASAN_PAGE_REDZONE);
+
+        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;
+
+        page = virt_to_head_page(object);
+
+        if (unlikely(!PageSlab(page)))
+                return kasan_kmalloc_large(object, size, flags);
+        else
+                return kasan_kmalloc(page->slab_cache, object, size, flags);
+}
+
+void kasan_poison_kfree(void *ptr, unsigned long ip)
+{
+        struct page *page;
+
+        page = virt_to_head_page(ptr);
+
+        if (unlikely(!PageSlab(page))) {
+                if (ptr != page_address(page)) {
+                        kasan_report_invalid_free(ptr, ip);
+                        return;
+                }
+                kasan_poison_shadow(ptr, PAGE_SIZE << compound_order(page),
+                                KASAN_FREE_PAGE);
+        } else {
+                __kasan_slab_free(page->slab_cache, ptr, ip, false);
+        }
+}
+
+void kasan_kfree_large(void *ptr, unsigned long ip)
+{
+        if (ptr != page_address(virt_to_head_page(ptr)))
+                kasan_report_invalid_free(ptr, ip);
+        /* The object will be poisoned by page_alloc. */
+}
+
+int kasan_module_alloc(void *addr, size_t size)
+{
+        void *ret;
+        size_t scaled_size;
+        size_t shadow_size;
+        unsigned long shadow_start;
+
+        shadow_start = (unsigned long)kasan_mem_to_shadow(addr);
+        scaled_size = (size + KASAN_SHADOW_MASK) >> KASAN_SHADOW_SCALE_SHIFT;
+        shadow_size = round_up(scaled_size, PAGE_SIZE);
+
+        if (WARN_ON(!PAGE_ALIGNED(shadow_start)))
+                return -EINVAL;
+
+        ret = __vmalloc_node_range(shadow_size, 1, shadow_start,
+                        shadow_start + shadow_size,
+                        GFP_KERNEL,
+                        PAGE_KERNEL, VM_NO_GUARD, NUMA_NO_NODE,
+                        __builtin_return_address(0));
+
+        if (ret) {
+                __memset(ret, KASAN_SHADOW_INIT, shadow_size);
+                find_vm_area(addr)->flags |= VM_KASAN;
+                kmemleak_ignore(ret);
+                return 0;
+        }
+
+        return -ENOMEM;
+}
+
+void kasan_free_shadow(const struct vm_struct *vm)
+{
+        if (vm->flags & VM_KASAN)
+                vfree(kasan_mem_to_shadow(vm->addr));
+}
+
+#ifdef CONFIG_MEMORY_HOTPLUG
+static bool shadow_mapped(unsigned long addr)
+{
+        pgd_t *pgd = pgd_offset_k(addr);
+        p4d_t *p4d;
+        pud_t *pud;
+        pmd_t *pmd;
+        pte_t *pte;
+
+        if (pgd_none(*pgd))
+                return false;
+        p4d = p4d_offset(pgd, addr);
+        if (p4d_none(*p4d))
+                return false;
+        pud = pud_offset(p4d, addr);
+        if (pud_none(*pud))
+                return false;
+
+        /*
+         * We can't use pud_large() or pud_huge(), the first one is
+         * arch-specific, the last one depends on HUGETLB_PAGE.  So let's abuse
+         * pud_bad(), if pud is bad then it's bad because it's huge.
+         */
+        if (pud_bad(*pud))
+                return true;
+        pmd = pmd_offset(pud, addr);
+        if (pmd_none(*pmd))
+                return false;
+
+        if (pmd_bad(*pmd))
+                return true;
+        pte = pte_offset_kernel(pmd, addr);
+        return !pte_none(*pte);
+}
+
+static int __meminit kasan_mem_notifier(struct notifier_block *nb,
+                        unsigned long action, void *data)
+{
+        struct memory_notify *mem_data = data;
+        unsigned long nr_shadow_pages, start_kaddr, shadow_start;
+        unsigned long shadow_end, shadow_size;
+
+        nr_shadow_pages = mem_data->nr_pages >> KASAN_SHADOW_SCALE_SHIFT;
+        start_kaddr = (unsigned long)pfn_to_kaddr(mem_data->start_pfn);
+        shadow_start = (unsigned long)kasan_mem_to_shadow((void *)start_kaddr);
+        shadow_size = nr_shadow_pages << PAGE_SHIFT;
+        shadow_end = shadow_start + shadow_size;
+
+        if (WARN_ON(mem_data->nr_pages % KASAN_SHADOW_SCALE_SIZE) ||
+                WARN_ON(start_kaddr % (KASAN_SHADOW_SCALE_SIZE << PAGE_SHIFT)))
+                return NOTIFY_BAD;
+
+        switch (action) {
+        case MEM_GOING_ONLINE: {
+                void *ret;
+
+                /*
+                 * If shadow is mapped already than it must have been mapped
+                 * during the boot. This could happen if we onlining previously
+                 * offlined memory.
+                 */
+                if (shadow_mapped(shadow_start))
+                        return NOTIFY_OK;
+
+                ret = __vmalloc_node_range(shadow_size, PAGE_SIZE, shadow_start,
+                                        shadow_end, GFP_KERNEL,
+                                        PAGE_KERNEL, VM_NO_GUARD,
+                                        pfn_to_nid(mem_data->start_pfn),
+                                        __builtin_return_address(0));
+                if (!ret)
+                        return NOTIFY_BAD;
+
+                kmemleak_ignore(ret);
+                return NOTIFY_OK;
+        }
+        case MEM_CANCEL_ONLINE:
+        case MEM_OFFLINE: {
+                struct vm_struct *vm;
+
+                /*
+                 * shadow_start was either mapped during boot by kasan_init()
+                 * or during memory online by __vmalloc_node_range().
+                 * In the latter case we can use vfree() to free shadow.
+                 * Non-NULL result of the find_vm_area() will tell us if
+                 * that was the second case.
+                 *
+                 * Currently it's not possible to free shadow mapped
+                 * during boot by kasan_init(). It's because the code
+                 * to do that hasn't been written yet. So we'll just
+                 * leak the memory.
+                 */
+                vm = find_vm_area((void *)shadow_start);
+                if (vm)
+                        vfree((void *)shadow_start);
+        }
+        }
+
+        return NOTIFY_OK;
+}
+
+static int __init kasan_memhotplug_init(void)
+{
+        hotplug_memory_notifier(kasan_mem_notifier, 0);
+
+        return 0;
+}
+
+core_initcall(kasan_memhotplug_init);
+#endif