| Message ID | abe5a7455189ebd8ba8306d011776507d45c2cec.1600987622.git.andreyknvl@google.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | kasan: add hardware tag-based mode for arm64 | expand |
On Fri, Sep 25, 2020 at 12:50AM +0200, Andrey Konovalov wrote: > This is a preparatory commit for the upcoming addition of a new hardware > tag-based (MTE-based) KASAN mode. > > The new mode won't be using shadow memory. Move all shadow-related code > to shadow.c, which is only enabled for software KASAN modes that use > shadow memory. > > No functional changes for software modes. > > Signed-off-by: Andrey Konovalov <andreyknvl@google.com> > Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com> Reviewed-by: Marco Elver <elver@google.com> > --- > Change-Id: Ic1c32ce72d4649848e9e6a1f2c8dd269c77673f2 > --- > mm/kasan/Makefile | 6 +- > mm/kasan/common.c | 486 +------------------------------------------- > mm/kasan/shadow.c | 505 ++++++++++++++++++++++++++++++++++++++++++++++ > 3 files changed, 510 insertions(+), 487 deletions(-) > create mode 100644 mm/kasan/shadow.c > > diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile > index 7cf685bb51bd..7cc1031e1ef8 100644 > --- a/mm/kasan/Makefile > +++ b/mm/kasan/Makefile > @@ -10,6 +10,7 @@ CFLAGS_REMOVE_generic_report.o = $(CC_FLAGS_FTRACE) > CFLAGS_REMOVE_init.o = $(CC_FLAGS_FTRACE) > CFLAGS_REMOVE_quarantine.o = $(CC_FLAGS_FTRACE) > CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE) > +CFLAGS_REMOVE_shadow.o = $(CC_FLAGS_FTRACE) > CFLAGS_REMOVE_tags.o = $(CC_FLAGS_FTRACE) > CFLAGS_REMOVE_tags_report.o = $(CC_FLAGS_FTRACE) > > @@ -26,9 +27,10 @@ CFLAGS_generic_report.o := $(CC_FLAGS_KASAN_RUNTIME) > CFLAGS_init.o := $(CC_FLAGS_KASAN_RUNTIME) > CFLAGS_quarantine.o := $(CC_FLAGS_KASAN_RUNTIME) > CFLAGS_report.o := $(CC_FLAGS_KASAN_RUNTIME) > +CFLAGS_shadow.o := $(CC_FLAGS_KASAN_RUNTIME) > CFLAGS_tags.o := $(CC_FLAGS_KASAN_RUNTIME) > CFLAGS_tags_report.o := $(CC_FLAGS_KASAN_RUNTIME) > > obj-$(CONFIG_KASAN) := common.o report.o > -obj-$(CONFIG_KASAN_GENERIC) += init.o generic.o generic_report.o quarantine.o > -obj-$(CONFIG_KASAN_SW_TAGS) += init.o tags.o tags_report.o > +obj-$(CONFIG_KASAN_GENERIC) += init.o generic.o generic_report.o shadow.o quarantine.o > +obj-$(CONFIG_KASAN_SW_TAGS) += init.o shadow.o tags.o tags_report.o > diff --git a/mm/kasan/common.c b/mm/kasan/common.c > index f65c9f792f8f..123abfb760d4 100644 > --- a/mm/kasan/common.c > +++ b/mm/kasan/common.c > @@ -1,6 +1,6 @@ > // SPDX-License-Identifier: GPL-2.0 > /* > - * This file contains common generic and tag-based KASAN code. > + * This file contains common KASAN code. > * > * Copyright (c) 2014 Samsung Electronics Co., Ltd. > * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> > @@ -13,7 +13,6 @@ > #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> > @@ -26,12 +25,8 @@ > #include <linux/stacktrace.h> > #include <linux/string.h> > #include <linux/types.h> > -#include <linux/vmalloc.h> > #include <linux/bug.h> > > -#include <asm/cacheflush.h> > -#include <asm/tlbflush.h> > - > #include "kasan.h" > #include "../slab.h" > > @@ -61,93 +56,6 @@ void kasan_disable_current(void) > current->kasan_depth--; > } > > -bool __kasan_check_read(const volatile void *p, unsigned int size) > -{ > - return check_memory_region((unsigned long)p, size, false, _RET_IP_); > -} > -EXPORT_SYMBOL(__kasan_check_read); > - > -bool __kasan_check_write(const volatile void *p, unsigned int size) > -{ > - return 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) > -{ > - if (!check_memory_region((unsigned long)addr, len, true, _RET_IP_)) > - return NULL; > - > - return __memset(addr, c, len); > -} > - > -#ifdef __HAVE_ARCH_MEMMOVE > -#undef memmove > -void *memmove(void *dest, const void *src, size_t len) > -{ > - if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || > - !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) > - return NULL; > - > - return __memmove(dest, src, len); > -} > -#endif > - > -#undef memcpy > -void *memcpy(void *dest, const void *src, size_t len) > -{ > - if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || > - !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) > - return NULL; > - > - return __memcpy(dest, src, len); > -} > - > -/* > - * Poisons the shadow memory for 'size' bytes starting from 'addr'. > - * Memory addresses should be aligned to KASAN_GRANULE_SIZE. > - */ > -void kasan_poison_memory(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_memory(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_memory(address, size, tag); > - > - if (size & KASAN_GRANULE_MASK) { > - u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size); > - > - if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) > - *shadow = tag; > - else > - *shadow = size & KASAN_GRANULE_MASK; > - } > -} > - > static void __kasan_unpoison_stack(struct task_struct *task, const void *sp) > { > void *base = task_stack_page(task); > @@ -535,395 +443,3 @@ void kasan_kfree_large(void *ptr, unsigned long ip) > kasan_report_invalid_free(ptr, ip); > /* The object will be poisoned by page_alloc. */ > } > - > -#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_GRANULE_SIZE) || > - WARN_ON(start_kaddr % (KASAN_GRANULE_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 > - > -#ifdef CONFIG_KASAN_VMALLOC > - > -static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr, > - void *unused) > -{ > - unsigned long page; > - pte_t pte; > - > - if (likely(!pte_none(*ptep))) > - return 0; > - > - page = __get_free_page(GFP_KERNEL); > - if (!page) > - return -ENOMEM; > - > - memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE); > - pte = pfn_pte(PFN_DOWN(__pa(page)), PAGE_KERNEL); > - > - spin_lock(&init_mm.page_table_lock); > - if (likely(pte_none(*ptep))) { > - set_pte_at(&init_mm, addr, ptep, pte); > - page = 0; > - } > - spin_unlock(&init_mm.page_table_lock); > - if (page) > - free_page(page); > - return 0; > -} > - > -int kasan_populate_vmalloc(unsigned long addr, unsigned long size) > -{ > - unsigned long shadow_start, shadow_end; > - int ret; > - > - if (!is_vmalloc_or_module_addr((void *)addr)) > - return 0; > - > - shadow_start = (unsigned long)kasan_mem_to_shadow((void *)addr); > - shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE); > - shadow_end = (unsigned long)kasan_mem_to_shadow((void *)addr + size); > - shadow_end = ALIGN(shadow_end, PAGE_SIZE); > - > - ret = apply_to_page_range(&init_mm, shadow_start, > - shadow_end - shadow_start, > - kasan_populate_vmalloc_pte, NULL); > - if (ret) > - return ret; > - > - flush_cache_vmap(shadow_start, shadow_end); > - > - /* > - * We need to be careful about inter-cpu effects here. Consider: > - * > - * CPU#0 CPU#1 > - * WRITE_ONCE(p, vmalloc(100)); while (x = READ_ONCE(p)) ; > - * p[99] = 1; > - * > - * With compiler instrumentation, that ends up looking like this: > - * > - * CPU#0 CPU#1 > - * // vmalloc() allocates memory > - * // let a = area->addr > - * // we reach kasan_populate_vmalloc > - * // and call kasan_unpoison_memory: > - * STORE shadow(a), unpoison_val > - * ... > - * STORE shadow(a+99), unpoison_val x = LOAD p > - * // rest of vmalloc process <data dependency> > - * STORE p, a LOAD shadow(x+99) > - * > - * If there is no barrier between the end of unpoisioning the shadow > - * and the store of the result to p, the stores could be committed > - * in a different order by CPU#0, and CPU#1 could erroneously observe > - * poison in the shadow. > - * > - * We need some sort of barrier between the stores. > - * > - * In the vmalloc() case, this is provided by a smp_wmb() in > - * clear_vm_uninitialized_flag(). In the per-cpu allocator and in > - * get_vm_area() and friends, the caller gets shadow allocated but > - * doesn't have any pages mapped into the virtual address space that > - * has been reserved. Mapping those pages in will involve taking and > - * releasing a page-table lock, which will provide the barrier. > - */ > - > - return 0; > -} > - > -/* > - * Poison the shadow for a vmalloc region. Called as part of the > - * freeing process at the time the region is freed. > - */ > -void kasan_poison_vmalloc(const void *start, unsigned long size) > -{ > - if (!is_vmalloc_or_module_addr(start)) > - return; > - > - size = round_up(size, KASAN_GRANULE_SIZE); > - kasan_poison_memory(start, size, KASAN_VMALLOC_INVALID); > -} > - > -void kasan_unpoison_vmalloc(const void *start, unsigned long size) > -{ > - if (!is_vmalloc_or_module_addr(start)) > - return; > - > - kasan_unpoison_memory(start, size); > -} > - > -static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr, > - void *unused) > -{ > - unsigned long page; > - > - page = (unsigned long)__va(pte_pfn(*ptep) << PAGE_SHIFT); > - > - spin_lock(&init_mm.page_table_lock); > - > - if (likely(!pte_none(*ptep))) { > - pte_clear(&init_mm, addr, ptep); > - free_page(page); > - } > - spin_unlock(&init_mm.page_table_lock); > - > - return 0; > -} > - > -/* > - * Release the backing for the vmalloc region [start, end), which > - * lies within the free region [free_region_start, free_region_end). > - * > - * This can be run lazily, long after the region was freed. It runs > - * under vmap_area_lock, so it's not safe to interact with the vmalloc/vmap > - * infrastructure. > - * > - * How does this work? > - * ------------------- > - * > - * We have a region that is page aligned, labelled as A. > - * That might not map onto the shadow in a way that is page-aligned: > - * > - * start end > - * v v > - * |????????|????????|AAAAAAAA|AA....AA|AAAAAAAA|????????| < vmalloc > - * -------- -------- -------- -------- -------- > - * | | | | | > - * | | | /-------/ | > - * \-------\|/------/ |/---------------/ > - * ||| || > - * |??AAAAAA|AAAAAAAA|AA??????| < shadow > - * (1) (2) (3) > - * > - * First we align the start upwards and the end downwards, so that the > - * shadow of the region aligns with shadow page boundaries. In the > - * example, this gives us the shadow page (2). This is the shadow entirely > - * covered by this allocation. > - * > - * Then we have the tricky bits. We want to know if we can free the > - * partially covered shadow pages - (1) and (3) in the example. For this, > - * we are given the start and end of the free region that contains this > - * allocation. Extending our previous example, we could have: > - * > - * free_region_start free_region_end > - * | start end | > - * v v v v > - * |FFFFFFFF|FFFFFFFF|AAAAAAAA|AA....AA|AAAAAAAA|FFFFFFFF| < vmalloc > - * -------- -------- -------- -------- -------- > - * | | | | | > - * | | | /-------/ | > - * \-------\|/------/ |/---------------/ > - * ||| || > - * |FFAAAAAA|AAAAAAAA|AAF?????| < shadow > - * (1) (2) (3) > - * > - * Once again, we align the start of the free region up, and the end of > - * the free region down so that the shadow is page aligned. So we can free > - * page (1) - we know no allocation currently uses anything in that page, > - * because all of it is in the vmalloc free region. But we cannot free > - * page (3), because we can't be sure that the rest of it is unused. > - * > - * We only consider pages that contain part of the original region for > - * freeing: we don't try to free other pages from the free region or we'd > - * end up trying to free huge chunks of virtual address space. > - * > - * Concurrency > - * ----------- > - * > - * How do we know that we're not freeing a page that is simultaneously > - * being used for a fresh allocation in kasan_populate_vmalloc(_pte)? > - * > - * We _can_ have kasan_release_vmalloc and kasan_populate_vmalloc running > - * at the same time. While we run under free_vmap_area_lock, the population > - * code does not. > - * > - * free_vmap_area_lock instead operates to ensure that the larger range > - * [free_region_start, free_region_end) is safe: because __alloc_vmap_area and > - * the per-cpu region-finding algorithm both run under free_vmap_area_lock, > - * no space identified as free will become used while we are running. This > - * means that so long as we are careful with alignment and only free shadow > - * pages entirely covered by the free region, we will not run in to any > - * trouble - any simultaneous allocations will be for disjoint regions. > - */ > -void kasan_release_vmalloc(unsigned long start, unsigned long end, > - unsigned long free_region_start, > - unsigned long free_region_end) > -{ > - void *shadow_start, *shadow_end; > - unsigned long region_start, region_end; > - unsigned long size; > - > - region_start = ALIGN(start, PAGE_SIZE * KASAN_GRANULE_SIZE); > - region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_GRANULE_SIZE); > - > - free_region_start = ALIGN(free_region_start, > - PAGE_SIZE * KASAN_GRANULE_SIZE); > - > - if (start != region_start && > - free_region_start < region_start) > - region_start -= PAGE_SIZE * KASAN_GRANULE_SIZE; > - > - free_region_end = ALIGN_DOWN(free_region_end, > - PAGE_SIZE * KASAN_GRANULE_SIZE); > - > - if (end != region_end && > - free_region_end > region_end) > - region_end += PAGE_SIZE * KASAN_GRANULE_SIZE; > - > - shadow_start = kasan_mem_to_shadow((void *)region_start); > - shadow_end = kasan_mem_to_shadow((void *)region_end); > - > - if (shadow_end > shadow_start) { > - size = shadow_end - shadow_start; > - apply_to_existing_page_range(&init_mm, > - (unsigned long)shadow_start, > - size, kasan_depopulate_vmalloc_pte, > - NULL); > - flush_tlb_kernel_range((unsigned long)shadow_start, > - (unsigned long)shadow_end); > - } > -} > - > -#else /* CONFIG_KASAN_VMALLOC */ > - > -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_GRANULE_SIZE - 1) >> > - 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)); > -} > - > -#endif > diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c > new file mode 100644 > index 000000000000..ca0cc4c31454 > --- /dev/null > +++ b/mm/kasan/shadow.c > @@ -0,0 +1,505 @@ > +// SPDX-License-Identifier: GPL-2.0 > +/* > + * This file contains KASAN runtime code that manages shadow memory for > + * generic and software tag-based KASAN modes. > + * > + * 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/init.h> > +#include <linux/kasan.h> > +#include <linux/kernel.h> > +#include <linux/kmemleak.h> > +#include <linux/memory.h> > +#include <linux/mm.h> > +#include <linux/string.h> > +#include <linux/types.h> > +#include <linux/vmalloc.h> > + > +#include <asm/cacheflush.h> > +#include <asm/tlbflush.h> > + > +#include "kasan.h" > + > +bool __kasan_check_read(const volatile void *p, unsigned int size) > +{ > + return check_memory_region((unsigned long)p, size, false, _RET_IP_); > +} > +EXPORT_SYMBOL(__kasan_check_read); > + > +bool __kasan_check_write(const volatile void *p, unsigned int size) > +{ > + return 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) > +{ > + if (!check_memory_region((unsigned long)addr, len, true, _RET_IP_)) > + return NULL; > + > + return __memset(addr, c, len); > +} > + > +#ifdef __HAVE_ARCH_MEMMOVE > +#undef memmove > +void *memmove(void *dest, const void *src, size_t len) > +{ > + if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || > + !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) > + return NULL; > + > + return __memmove(dest, src, len); > +} > +#endif > + > +#undef memcpy > +void *memcpy(void *dest, const void *src, size_t len) > +{ > + if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || > + !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) > + return NULL; > + > + return __memcpy(dest, src, len); > +} > + > +/* > + * Poisons the shadow memory for 'size' bytes starting from 'addr'. > + * Memory addresses should be aligned to KASAN_GRANULE_SIZE. > + */ > +void kasan_poison_memory(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_memory(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_memory(address, size, tag); > + > + if (size & KASAN_GRANULE_MASK) { > + u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size); > + > + if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) > + *shadow = tag; > + else > + *shadow = size & KASAN_GRANULE_MASK; > + } > +} > + > +#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_GRANULE_SIZE) || > + WARN_ON(start_kaddr % (KASAN_GRANULE_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 > + > +#ifdef CONFIG_KASAN_VMALLOC > + > +static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr, > + void *unused) > +{ > + unsigned long page; > + pte_t pte; > + > + if (likely(!pte_none(*ptep))) > + return 0; > + > + page = __get_free_page(GFP_KERNEL); > + if (!page) > + return -ENOMEM; > + > + memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE); > + pte = pfn_pte(PFN_DOWN(__pa(page)), PAGE_KERNEL); > + > + spin_lock(&init_mm.page_table_lock); > + if (likely(pte_none(*ptep))) { > + set_pte_at(&init_mm, addr, ptep, pte); > + page = 0; > + } > + spin_unlock(&init_mm.page_table_lock); > + if (page) > + free_page(page); > + return 0; > +} > + > +int kasan_populate_vmalloc(unsigned long addr, unsigned long size) > +{ > + unsigned long shadow_start, shadow_end; > + int ret; > + > + if (!is_vmalloc_or_module_addr((void *)addr)) > + return 0; > + > + shadow_start = (unsigned long)kasan_mem_to_shadow((void *)addr); > + shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE); > + shadow_end = (unsigned long)kasan_mem_to_shadow((void *)addr + size); > + shadow_end = ALIGN(shadow_end, PAGE_SIZE); > + > + ret = apply_to_page_range(&init_mm, shadow_start, > + shadow_end - shadow_start, > + kasan_populate_vmalloc_pte, NULL); > + if (ret) > + return ret; > + > + flush_cache_vmap(shadow_start, shadow_end); > + > + /* > + * We need to be careful about inter-cpu effects here. Consider: > + * > + * CPU#0 CPU#1 > + * WRITE_ONCE(p, vmalloc(100)); while (x = READ_ONCE(p)) ; > + * p[99] = 1; > + * > + * With compiler instrumentation, that ends up looking like this: > + * > + * CPU#0 CPU#1 > + * // vmalloc() allocates memory > + * // let a = area->addr > + * // we reach kasan_populate_vmalloc > + * // and call kasan_unpoison_memory: > + * STORE shadow(a), unpoison_val > + * ... > + * STORE shadow(a+99), unpoison_val x = LOAD p > + * // rest of vmalloc process <data dependency> > + * STORE p, a LOAD shadow(x+99) > + * > + * If there is no barrier between the end of unpoisioning the shadow > + * and the store of the result to p, the stores could be committed > + * in a different order by CPU#0, and CPU#1 could erroneously observe > + * poison in the shadow. > + * > + * We need some sort of barrier between the stores. > + * > + * In the vmalloc() case, this is provided by a smp_wmb() in > + * clear_vm_uninitialized_flag(). In the per-cpu allocator and in > + * get_vm_area() and friends, the caller gets shadow allocated but > + * doesn't have any pages mapped into the virtual address space that > + * has been reserved. Mapping those pages in will involve taking and > + * releasing a page-table lock, which will provide the barrier. > + */ > + > + return 0; > +} > + > +/* > + * Poison the shadow for a vmalloc region. Called as part of the > + * freeing process at the time the region is freed. > + */ > +void kasan_poison_vmalloc(const void *start, unsigned long size) > +{ > + if (!is_vmalloc_or_module_addr(start)) > + return; > + > + size = round_up(size, KASAN_GRANULE_SIZE); > + kasan_poison_memory(start, size, KASAN_VMALLOC_INVALID); > +} > + > +void kasan_unpoison_vmalloc(const void *start, unsigned long size) > +{ > + if (!is_vmalloc_or_module_addr(start)) > + return; > + > + kasan_unpoison_memory(start, size); > +} > + > +static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr, > + void *unused) > +{ > + unsigned long page; > + > + page = (unsigned long)__va(pte_pfn(*ptep) << PAGE_SHIFT); > + > + spin_lock(&init_mm.page_table_lock); > + > + if (likely(!pte_none(*ptep))) { > + pte_clear(&init_mm, addr, ptep); > + free_page(page); > + } > + spin_unlock(&init_mm.page_table_lock); > + > + return 0; > +} > + > +/* > + * Release the backing for the vmalloc region [start, end), which > + * lies within the free region [free_region_start, free_region_end). > + * > + * This can be run lazily, long after the region was freed. It runs > + * under vmap_area_lock, so it's not safe to interact with the vmalloc/vmap > + * infrastructure. > + * > + * How does this work? > + * ------------------- > + * > + * We have a region that is page aligned, labelled as A. > + * That might not map onto the shadow in a way that is page-aligned: > + * > + * start end > + * v v > + * |????????|????????|AAAAAAAA|AA....AA|AAAAAAAA|????????| < vmalloc > + * -------- -------- -------- -------- -------- > + * | | | | | > + * | | | /-------/ | > + * \-------\|/------/ |/---------------/ > + * ||| || > + * |??AAAAAA|AAAAAAAA|AA??????| < shadow > + * (1) (2) (3) > + * > + * First we align the start upwards and the end downwards, so that the > + * shadow of the region aligns with shadow page boundaries. In the > + * example, this gives us the shadow page (2). This is the shadow entirely > + * covered by this allocation. > + * > + * Then we have the tricky bits. We want to know if we can free the > + * partially covered shadow pages - (1) and (3) in the example. For this, > + * we are given the start and end of the free region that contains this > + * allocation. Extending our previous example, we could have: > + * > + * free_region_start free_region_end > + * | start end | > + * v v v v > + * |FFFFFFFF|FFFFFFFF|AAAAAAAA|AA....AA|AAAAAAAA|FFFFFFFF| < vmalloc > + * -------- -------- -------- -------- -------- > + * | | | | | > + * | | | /-------/ | > + * \-------\|/------/ |/---------------/ > + * ||| || > + * |FFAAAAAA|AAAAAAAA|AAF?????| < shadow > + * (1) (2) (3) > + * > + * Once again, we align the start of the free region up, and the end of > + * the free region down so that the shadow is page aligned. So we can free > + * page (1) - we know no allocation currently uses anything in that page, > + * because all of it is in the vmalloc free region. But we cannot free > + * page (3), because we can't be sure that the rest of it is unused. > + * > + * We only consider pages that contain part of the original region for > + * freeing: we don't try to free other pages from the free region or we'd > + * end up trying to free huge chunks of virtual address space. > + * > + * Concurrency > + * ----------- > + * > + * How do we know that we're not freeing a page that is simultaneously > + * being used for a fresh allocation in kasan_populate_vmalloc(_pte)? > + * > + * We _can_ have kasan_release_vmalloc and kasan_populate_vmalloc running > + * at the same time. While we run under free_vmap_area_lock, the population > + * code does not. > + * > + * free_vmap_area_lock instead operates to ensure that the larger range > + * [free_region_start, free_region_end) is safe: because __alloc_vmap_area and > + * the per-cpu region-finding algorithm both run under free_vmap_area_lock, > + * no space identified as free will become used while we are running. This > + * means that so long as we are careful with alignment and only free shadow > + * pages entirely covered by the free region, we will not run in to any > + * trouble - any simultaneous allocations will be for disjoint regions. > + */ > +void kasan_release_vmalloc(unsigned long start, unsigned long end, > + unsigned long free_region_start, > + unsigned long free_region_end) > +{ > + void *shadow_start, *shadow_end; > + unsigned long region_start, region_end; > + unsigned long size; > + > + region_start = ALIGN(start, PAGE_SIZE * KASAN_GRANULE_SIZE); > + region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_GRANULE_SIZE); > + > + free_region_start = ALIGN(free_region_start, > + PAGE_SIZE * KASAN_GRANULE_SIZE); > + > + if (start != region_start && > + free_region_start < region_start) > + region_start -= PAGE_SIZE * KASAN_GRANULE_SIZE; > + > + free_region_end = ALIGN_DOWN(free_region_end, > + PAGE_SIZE * KASAN_GRANULE_SIZE); > + > + if (end != region_end && > + free_region_end > region_end) > + region_end += PAGE_SIZE * KASAN_GRANULE_SIZE; > + > + shadow_start = kasan_mem_to_shadow((void *)region_start); > + shadow_end = kasan_mem_to_shadow((void *)region_end); > + > + if (shadow_end > shadow_start) { > + size = shadow_end - shadow_start; > + apply_to_existing_page_range(&init_mm, > + (unsigned long)shadow_start, > + size, kasan_depopulate_vmalloc_pte, > + NULL); > + flush_tlb_kernel_range((unsigned long)shadow_start, > + (unsigned long)shadow_end); > + } > +} > + > +#else /* CONFIG_KASAN_VMALLOC */ > + > +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_GRANULE_SIZE - 1) >> > + 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)); > +} > + > +#endif > -- > 2.28.0.681.g6f77f65b4e-goog >
diff --git a/mm/kasan/Makefile b/mm/kasan/Makefile index 7cf685bb51bd..7cc1031e1ef8 100644 --- a/mm/kasan/Makefile +++ b/mm/kasan/Makefile @@ -10,6 +10,7 @@ CFLAGS_REMOVE_generic_report.o = $(CC_FLAGS_FTRACE) CFLAGS_REMOVE_init.o = $(CC_FLAGS_FTRACE) CFLAGS_REMOVE_quarantine.o = $(CC_FLAGS_FTRACE) CFLAGS_REMOVE_report.o = $(CC_FLAGS_FTRACE) +CFLAGS_REMOVE_shadow.o = $(CC_FLAGS_FTRACE) CFLAGS_REMOVE_tags.o = $(CC_FLAGS_FTRACE) CFLAGS_REMOVE_tags_report.o = $(CC_FLAGS_FTRACE) @@ -26,9 +27,10 @@ CFLAGS_generic_report.o := $(CC_FLAGS_KASAN_RUNTIME) CFLAGS_init.o := $(CC_FLAGS_KASAN_RUNTIME) CFLAGS_quarantine.o := $(CC_FLAGS_KASAN_RUNTIME) CFLAGS_report.o := $(CC_FLAGS_KASAN_RUNTIME) +CFLAGS_shadow.o := $(CC_FLAGS_KASAN_RUNTIME) CFLAGS_tags.o := $(CC_FLAGS_KASAN_RUNTIME) CFLAGS_tags_report.o := $(CC_FLAGS_KASAN_RUNTIME) obj-$(CONFIG_KASAN) := common.o report.o -obj-$(CONFIG_KASAN_GENERIC) += init.o generic.o generic_report.o quarantine.o -obj-$(CONFIG_KASAN_SW_TAGS) += init.o tags.o tags_report.o +obj-$(CONFIG_KASAN_GENERIC) += init.o generic.o generic_report.o shadow.o quarantine.o +obj-$(CONFIG_KASAN_SW_TAGS) += init.o shadow.o tags.o tags_report.o diff --git a/mm/kasan/common.c b/mm/kasan/common.c index f65c9f792f8f..123abfb760d4 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -1,6 +1,6 @@ // SPDX-License-Identifier: GPL-2.0 /* - * This file contains common generic and tag-based KASAN code. + * This file contains common KASAN code. * * Copyright (c) 2014 Samsung Electronics Co., Ltd. * Author: Andrey Ryabinin <ryabinin.a.a@gmail.com> @@ -13,7 +13,6 @@ #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> @@ -26,12 +25,8 @@ #include <linux/stacktrace.h> #include <linux/string.h> #include <linux/types.h> -#include <linux/vmalloc.h> #include <linux/bug.h> -#include <asm/cacheflush.h> -#include <asm/tlbflush.h> - #include "kasan.h" #include "../slab.h" @@ -61,93 +56,6 @@ void kasan_disable_current(void) current->kasan_depth--; } -bool __kasan_check_read(const volatile void *p, unsigned int size) -{ - return check_memory_region((unsigned long)p, size, false, _RET_IP_); -} -EXPORT_SYMBOL(__kasan_check_read); - -bool __kasan_check_write(const volatile void *p, unsigned int size) -{ - return 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) -{ - if (!check_memory_region((unsigned long)addr, len, true, _RET_IP_)) - return NULL; - - return __memset(addr, c, len); -} - -#ifdef __HAVE_ARCH_MEMMOVE -#undef memmove -void *memmove(void *dest, const void *src, size_t len) -{ - if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || - !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) - return NULL; - - return __memmove(dest, src, len); -} -#endif - -#undef memcpy -void *memcpy(void *dest, const void *src, size_t len) -{ - if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || - !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) - return NULL; - - return __memcpy(dest, src, len); -} - -/* - * Poisons the shadow memory for 'size' bytes starting from 'addr'. - * Memory addresses should be aligned to KASAN_GRANULE_SIZE. - */ -void kasan_poison_memory(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_memory(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_memory(address, size, tag); - - if (size & KASAN_GRANULE_MASK) { - u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size); - - if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) - *shadow = tag; - else - *shadow = size & KASAN_GRANULE_MASK; - } -} - static void __kasan_unpoison_stack(struct task_struct *task, const void *sp) { void *base = task_stack_page(task); @@ -535,395 +443,3 @@ void kasan_kfree_large(void *ptr, unsigned long ip) kasan_report_invalid_free(ptr, ip); /* The object will be poisoned by page_alloc. */ } - -#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_GRANULE_SIZE) || - WARN_ON(start_kaddr % (KASAN_GRANULE_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 - -#ifdef CONFIG_KASAN_VMALLOC - -static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr, - void *unused) -{ - unsigned long page; - pte_t pte; - - if (likely(!pte_none(*ptep))) - return 0; - - page = __get_free_page(GFP_KERNEL); - if (!page) - return -ENOMEM; - - memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE); - pte = pfn_pte(PFN_DOWN(__pa(page)), PAGE_KERNEL); - - spin_lock(&init_mm.page_table_lock); - if (likely(pte_none(*ptep))) { - set_pte_at(&init_mm, addr, ptep, pte); - page = 0; - } - spin_unlock(&init_mm.page_table_lock); - if (page) - free_page(page); - return 0; -} - -int kasan_populate_vmalloc(unsigned long addr, unsigned long size) -{ - unsigned long shadow_start, shadow_end; - int ret; - - if (!is_vmalloc_or_module_addr((void *)addr)) - return 0; - - shadow_start = (unsigned long)kasan_mem_to_shadow((void *)addr); - shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE); - shadow_end = (unsigned long)kasan_mem_to_shadow((void *)addr + size); - shadow_end = ALIGN(shadow_end, PAGE_SIZE); - - ret = apply_to_page_range(&init_mm, shadow_start, - shadow_end - shadow_start, - kasan_populate_vmalloc_pte, NULL); - if (ret) - return ret; - - flush_cache_vmap(shadow_start, shadow_end); - - /* - * We need to be careful about inter-cpu effects here. Consider: - * - * CPU#0 CPU#1 - * WRITE_ONCE(p, vmalloc(100)); while (x = READ_ONCE(p)) ; - * p[99] = 1; - * - * With compiler instrumentation, that ends up looking like this: - * - * CPU#0 CPU#1 - * // vmalloc() allocates memory - * // let a = area->addr - * // we reach kasan_populate_vmalloc - * // and call kasan_unpoison_memory: - * STORE shadow(a), unpoison_val - * ... - * STORE shadow(a+99), unpoison_val x = LOAD p - * // rest of vmalloc process <data dependency> - * STORE p, a LOAD shadow(x+99) - * - * If there is no barrier between the end of unpoisioning the shadow - * and the store of the result to p, the stores could be committed - * in a different order by CPU#0, and CPU#1 could erroneously observe - * poison in the shadow. - * - * We need some sort of barrier between the stores. - * - * In the vmalloc() case, this is provided by a smp_wmb() in - * clear_vm_uninitialized_flag(). In the per-cpu allocator and in - * get_vm_area() and friends, the caller gets shadow allocated but - * doesn't have any pages mapped into the virtual address space that - * has been reserved. Mapping those pages in will involve taking and - * releasing a page-table lock, which will provide the barrier. - */ - - return 0; -} - -/* - * Poison the shadow for a vmalloc region. Called as part of the - * freeing process at the time the region is freed. - */ -void kasan_poison_vmalloc(const void *start, unsigned long size) -{ - if (!is_vmalloc_or_module_addr(start)) - return; - - size = round_up(size, KASAN_GRANULE_SIZE); - kasan_poison_memory(start, size, KASAN_VMALLOC_INVALID); -} - -void kasan_unpoison_vmalloc(const void *start, unsigned long size) -{ - if (!is_vmalloc_or_module_addr(start)) - return; - - kasan_unpoison_memory(start, size); -} - -static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr, - void *unused) -{ - unsigned long page; - - page = (unsigned long)__va(pte_pfn(*ptep) << PAGE_SHIFT); - - spin_lock(&init_mm.page_table_lock); - - if (likely(!pte_none(*ptep))) { - pte_clear(&init_mm, addr, ptep); - free_page(page); - } - spin_unlock(&init_mm.page_table_lock); - - return 0; -} - -/* - * Release the backing for the vmalloc region [start, end), which - * lies within the free region [free_region_start, free_region_end). - * - * This can be run lazily, long after the region was freed. It runs - * under vmap_area_lock, so it's not safe to interact with the vmalloc/vmap - * infrastructure. - * - * How does this work? - * ------------------- - * - * We have a region that is page aligned, labelled as A. - * That might not map onto the shadow in a way that is page-aligned: - * - * start end - * v v - * |????????|????????|AAAAAAAA|AA....AA|AAAAAAAA|????????| < vmalloc - * -------- -------- -------- -------- -------- - * | | | | | - * | | | /-------/ | - * \-------\|/------/ |/---------------/ - * ||| || - * |??AAAAAA|AAAAAAAA|AA??????| < shadow - * (1) (2) (3) - * - * First we align the start upwards and the end downwards, so that the - * shadow of the region aligns with shadow page boundaries. In the - * example, this gives us the shadow page (2). This is the shadow entirely - * covered by this allocation. - * - * Then we have the tricky bits. We want to know if we can free the - * partially covered shadow pages - (1) and (3) in the example. For this, - * we are given the start and end of the free region that contains this - * allocation. Extending our previous example, we could have: - * - * free_region_start free_region_end - * | start end | - * v v v v - * |FFFFFFFF|FFFFFFFF|AAAAAAAA|AA....AA|AAAAAAAA|FFFFFFFF| < vmalloc - * -------- -------- -------- -------- -------- - * | | | | | - * | | | /-------/ | - * \-------\|/------/ |/---------------/ - * ||| || - * |FFAAAAAA|AAAAAAAA|AAF?????| < shadow - * (1) (2) (3) - * - * Once again, we align the start of the free region up, and the end of - * the free region down so that the shadow is page aligned. So we can free - * page (1) - we know no allocation currently uses anything in that page, - * because all of it is in the vmalloc free region. But we cannot free - * page (3), because we can't be sure that the rest of it is unused. - * - * We only consider pages that contain part of the original region for - * freeing: we don't try to free other pages from the free region or we'd - * end up trying to free huge chunks of virtual address space. - * - * Concurrency - * ----------- - * - * How do we know that we're not freeing a page that is simultaneously - * being used for a fresh allocation in kasan_populate_vmalloc(_pte)? - * - * We _can_ have kasan_release_vmalloc and kasan_populate_vmalloc running - * at the same time. While we run under free_vmap_area_lock, the population - * code does not. - * - * free_vmap_area_lock instead operates to ensure that the larger range - * [free_region_start, free_region_end) is safe: because __alloc_vmap_area and - * the per-cpu region-finding algorithm both run under free_vmap_area_lock, - * no space identified as free will become used while we are running. This - * means that so long as we are careful with alignment and only free shadow - * pages entirely covered by the free region, we will not run in to any - * trouble - any simultaneous allocations will be for disjoint regions. - */ -void kasan_release_vmalloc(unsigned long start, unsigned long end, - unsigned long free_region_start, - unsigned long free_region_end) -{ - void *shadow_start, *shadow_end; - unsigned long region_start, region_end; - unsigned long size; - - region_start = ALIGN(start, PAGE_SIZE * KASAN_GRANULE_SIZE); - region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_GRANULE_SIZE); - - free_region_start = ALIGN(free_region_start, - PAGE_SIZE * KASAN_GRANULE_SIZE); - - if (start != region_start && - free_region_start < region_start) - region_start -= PAGE_SIZE * KASAN_GRANULE_SIZE; - - free_region_end = ALIGN_DOWN(free_region_end, - PAGE_SIZE * KASAN_GRANULE_SIZE); - - if (end != region_end && - free_region_end > region_end) - region_end += PAGE_SIZE * KASAN_GRANULE_SIZE; - - shadow_start = kasan_mem_to_shadow((void *)region_start); - shadow_end = kasan_mem_to_shadow((void *)region_end); - - if (shadow_end > shadow_start) { - size = shadow_end - shadow_start; - apply_to_existing_page_range(&init_mm, - (unsigned long)shadow_start, - size, kasan_depopulate_vmalloc_pte, - NULL); - flush_tlb_kernel_range((unsigned long)shadow_start, - (unsigned long)shadow_end); - } -} - -#else /* CONFIG_KASAN_VMALLOC */ - -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_GRANULE_SIZE - 1) >> - 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)); -} - -#endif diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c new file mode 100644 index 000000000000..ca0cc4c31454 --- /dev/null +++ b/mm/kasan/shadow.c @@ -0,0 +1,505 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * This file contains KASAN runtime code that manages shadow memory for + * generic and software tag-based KASAN modes. + * + * 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/init.h> +#include <linux/kasan.h> +#include <linux/kernel.h> +#include <linux/kmemleak.h> +#include <linux/memory.h> +#include <linux/mm.h> +#include <linux/string.h> +#include <linux/types.h> +#include <linux/vmalloc.h> + +#include <asm/cacheflush.h> +#include <asm/tlbflush.h> + +#include "kasan.h" + +bool __kasan_check_read(const volatile void *p, unsigned int size) +{ + return check_memory_region((unsigned long)p, size, false, _RET_IP_); +} +EXPORT_SYMBOL(__kasan_check_read); + +bool __kasan_check_write(const volatile void *p, unsigned int size) +{ + return 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) +{ + if (!check_memory_region((unsigned long)addr, len, true, _RET_IP_)) + return NULL; + + return __memset(addr, c, len); +} + +#ifdef __HAVE_ARCH_MEMMOVE +#undef memmove +void *memmove(void *dest, const void *src, size_t len) +{ + if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || + !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) + return NULL; + + return __memmove(dest, src, len); +} +#endif + +#undef memcpy +void *memcpy(void *dest, const void *src, size_t len) +{ + if (!check_memory_region((unsigned long)src, len, false, _RET_IP_) || + !check_memory_region((unsigned long)dest, len, true, _RET_IP_)) + return NULL; + + return __memcpy(dest, src, len); +} + +/* + * Poisons the shadow memory for 'size' bytes starting from 'addr'. + * Memory addresses should be aligned to KASAN_GRANULE_SIZE. + */ +void kasan_poison_memory(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_memory(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_memory(address, size, tag); + + if (size & KASAN_GRANULE_MASK) { + u8 *shadow = (u8 *)kasan_mem_to_shadow(address + size); + + if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) + *shadow = tag; + else + *shadow = size & KASAN_GRANULE_MASK; + } +} + +#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_GRANULE_SIZE) || + WARN_ON(start_kaddr % (KASAN_GRANULE_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 + +#ifdef CONFIG_KASAN_VMALLOC + +static int kasan_populate_vmalloc_pte(pte_t *ptep, unsigned long addr, + void *unused) +{ + unsigned long page; + pte_t pte; + + if (likely(!pte_none(*ptep))) + return 0; + + page = __get_free_page(GFP_KERNEL); + if (!page) + return -ENOMEM; + + memset((void *)page, KASAN_VMALLOC_INVALID, PAGE_SIZE); + pte = pfn_pte(PFN_DOWN(__pa(page)), PAGE_KERNEL); + + spin_lock(&init_mm.page_table_lock); + if (likely(pte_none(*ptep))) { + set_pte_at(&init_mm, addr, ptep, pte); + page = 0; + } + spin_unlock(&init_mm.page_table_lock); + if (page) + free_page(page); + return 0; +} + +int kasan_populate_vmalloc(unsigned long addr, unsigned long size) +{ + unsigned long shadow_start, shadow_end; + int ret; + + if (!is_vmalloc_or_module_addr((void *)addr)) + return 0; + + shadow_start = (unsigned long)kasan_mem_to_shadow((void *)addr); + shadow_start = ALIGN_DOWN(shadow_start, PAGE_SIZE); + shadow_end = (unsigned long)kasan_mem_to_shadow((void *)addr + size); + shadow_end = ALIGN(shadow_end, PAGE_SIZE); + + ret = apply_to_page_range(&init_mm, shadow_start, + shadow_end - shadow_start, + kasan_populate_vmalloc_pte, NULL); + if (ret) + return ret; + + flush_cache_vmap(shadow_start, shadow_end); + + /* + * We need to be careful about inter-cpu effects here. Consider: + * + * CPU#0 CPU#1 + * WRITE_ONCE(p, vmalloc(100)); while (x = READ_ONCE(p)) ; + * p[99] = 1; + * + * With compiler instrumentation, that ends up looking like this: + * + * CPU#0 CPU#1 + * // vmalloc() allocates memory + * // let a = area->addr + * // we reach kasan_populate_vmalloc + * // and call kasan_unpoison_memory: + * STORE shadow(a), unpoison_val + * ... + * STORE shadow(a+99), unpoison_val x = LOAD p + * // rest of vmalloc process <data dependency> + * STORE p, a LOAD shadow(x+99) + * + * If there is no barrier between the end of unpoisioning the shadow + * and the store of the result to p, the stores could be committed + * in a different order by CPU#0, and CPU#1 could erroneously observe + * poison in the shadow. + * + * We need some sort of barrier between the stores. + * + * In the vmalloc() case, this is provided by a smp_wmb() in + * clear_vm_uninitialized_flag(). In the per-cpu allocator and in + * get_vm_area() and friends, the caller gets shadow allocated but + * doesn't have any pages mapped into the virtual address space that + * has been reserved. Mapping those pages in will involve taking and + * releasing a page-table lock, which will provide the barrier. + */ + + return 0; +} + +/* + * Poison the shadow for a vmalloc region. Called as part of the + * freeing process at the time the region is freed. + */ +void kasan_poison_vmalloc(const void *start, unsigned long size) +{ + if (!is_vmalloc_or_module_addr(start)) + return; + + size = round_up(size, KASAN_GRANULE_SIZE); + kasan_poison_memory(start, size, KASAN_VMALLOC_INVALID); +} + +void kasan_unpoison_vmalloc(const void *start, unsigned long size) +{ + if (!is_vmalloc_or_module_addr(start)) + return; + + kasan_unpoison_memory(start, size); +} + +static int kasan_depopulate_vmalloc_pte(pte_t *ptep, unsigned long addr, + void *unused) +{ + unsigned long page; + + page = (unsigned long)__va(pte_pfn(*ptep) << PAGE_SHIFT); + + spin_lock(&init_mm.page_table_lock); + + if (likely(!pte_none(*ptep))) { + pte_clear(&init_mm, addr, ptep); + free_page(page); + } + spin_unlock(&init_mm.page_table_lock); + + return 0; +} + +/* + * Release the backing for the vmalloc region [start, end), which + * lies within the free region [free_region_start, free_region_end). + * + * This can be run lazily, long after the region was freed. It runs + * under vmap_area_lock, so it's not safe to interact with the vmalloc/vmap + * infrastructure. + * + * How does this work? + * ------------------- + * + * We have a region that is page aligned, labelled as A. + * That might not map onto the shadow in a way that is page-aligned: + * + * start end + * v v + * |????????|????????|AAAAAAAA|AA....AA|AAAAAAAA|????????| < vmalloc + * -------- -------- -------- -------- -------- + * | | | | | + * | | | /-------/ | + * \-------\|/------/ |/---------------/ + * ||| || + * |??AAAAAA|AAAAAAAA|AA??????| < shadow + * (1) (2) (3) + * + * First we align the start upwards and the end downwards, so that the + * shadow of the region aligns with shadow page boundaries. In the + * example, this gives us the shadow page (2). This is the shadow entirely + * covered by this allocation. + * + * Then we have the tricky bits. We want to know if we can free the + * partially covered shadow pages - (1) and (3) in the example. For this, + * we are given the start and end of the free region that contains this + * allocation. Extending our previous example, we could have: + * + * free_region_start free_region_end + * | start end | + * v v v v + * |FFFFFFFF|FFFFFFFF|AAAAAAAA|AA....AA|AAAAAAAA|FFFFFFFF| < vmalloc + * -------- -------- -------- -------- -------- + * | | | | | + * | | | /-------/ | + * \-------\|/------/ |/---------------/ + * ||| || + * |FFAAAAAA|AAAAAAAA|AAF?????| < shadow + * (1) (2) (3) + * + * Once again, we align the start of the free region up, and the end of + * the free region down so that the shadow is page aligned. So we can free + * page (1) - we know no allocation currently uses anything in that page, + * because all of it is in the vmalloc free region. But we cannot free + * page (3), because we can't be sure that the rest of it is unused. + * + * We only consider pages that contain part of the original region for + * freeing: we don't try to free other pages from the free region or we'd + * end up trying to free huge chunks of virtual address space. + * + * Concurrency + * ----------- + * + * How do we know that we're not freeing a page that is simultaneously + * being used for a fresh allocation in kasan_populate_vmalloc(_pte)? + * + * We _can_ have kasan_release_vmalloc and kasan_populate_vmalloc running + * at the same time. While we run under free_vmap_area_lock, the population + * code does not. + * + * free_vmap_area_lock instead operates to ensure that the larger range + * [free_region_start, free_region_end) is safe: because __alloc_vmap_area and + * the per-cpu region-finding algorithm both run under free_vmap_area_lock, + * no space identified as free will become used while we are running. This + * means that so long as we are careful with alignment and only free shadow + * pages entirely covered by the free region, we will not run in to any + * trouble - any simultaneous allocations will be for disjoint regions. + */ +void kasan_release_vmalloc(unsigned long start, unsigned long end, + unsigned long free_region_start, + unsigned long free_region_end) +{ + void *shadow_start, *shadow_end; + unsigned long region_start, region_end; + unsigned long size; + + region_start = ALIGN(start, PAGE_SIZE * KASAN_GRANULE_SIZE); + region_end = ALIGN_DOWN(end, PAGE_SIZE * KASAN_GRANULE_SIZE); + + free_region_start = ALIGN(free_region_start, + PAGE_SIZE * KASAN_GRANULE_SIZE); + + if (start != region_start && + free_region_start < region_start) + region_start -= PAGE_SIZE * KASAN_GRANULE_SIZE; + + free_region_end = ALIGN_DOWN(free_region_end, + PAGE_SIZE * KASAN_GRANULE_SIZE); + + if (end != region_end && + free_region_end > region_end) + region_end += PAGE_SIZE * KASAN_GRANULE_SIZE; + + shadow_start = kasan_mem_to_shadow((void *)region_start); + shadow_end = kasan_mem_to_shadow((void *)region_end); + + if (shadow_end > shadow_start) { + size = shadow_end - shadow_start; + apply_to_existing_page_range(&init_mm, + (unsigned long)shadow_start, + size, kasan_depopulate_vmalloc_pte, + NULL); + flush_tlb_kernel_range((unsigned long)shadow_start, + (unsigned long)shadow_end); + } +} + +#else /* CONFIG_KASAN_VMALLOC */ + +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_GRANULE_SIZE - 1) >> + 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)); +} + +#endif