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author | Andrey Konovalov <andreyknvl@google.com> | 2020-12-22 23:00:39 +0300 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2020-12-22 23:55:06 +0300 |
commit | 59fd51b2ba6b02e0f7c989fc12c3537988f8c8fe (patch) | |
tree | f086e90b268790974c2f3e430fb6d351dd7a5a16 /mm/kasan/tags.c | |
parent | affc3f07759cfdcb1ffd87f2847b1c27d8781d65 (diff) | |
download | linux-59fd51b2ba6b02e0f7c989fc12c3537988f8c8fe.tar.xz |
kasan: rename report and tags files
Rename generic_report.c to report_generic.c and tags_report.c to
report_sw_tags.c, as their content is more relevant to report.c file.
Also rename tags.c to sw_tags.c to better reflect that this file contains
code for software tag-based mode.
No functional changes.
Link: https://lkml.kernel.org/r/a6105d416da97d389580015afed66c4c3cfd4c08.1606161801.git.andreyknvl@google.com
Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Alexander Potapenko <glider@google.com>
Tested-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Andrey Ryabinin <aryabinin@virtuozzo.com>
Cc: Branislav Rankov <Branislav.Rankov@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Evgenii Stepanov <eugenis@google.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/kasan/tags.c')
-rw-r--r-- | mm/kasan/tags.c | 195 |
1 files changed, 0 insertions, 195 deletions
diff --git a/mm/kasan/tags.c b/mm/kasan/tags.c deleted file mode 100644 index c0b3f327812b..000000000000 --- a/mm/kasan/tags.c +++ /dev/null @@ -1,195 +0,0 @@ -// SPDX-License-Identifier: GPL-2.0 -/* - * This file contains core tag-based KASAN code. - * - * Copyright (c) 2018 Google, Inc. - * Author: Andrey Konovalov <andreyknvl@google.com> - */ - -#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt - -#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/random.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 DEFINE_PER_CPU(u32, prng_state); - -void kasan_init_tags(void) -{ - int cpu; - - for_each_possible_cpu(cpu) - per_cpu(prng_state, cpu) = (u32)get_cycles(); -} - -/* - * If a preemption happens between this_cpu_read and this_cpu_write, the only - * side effect is that we'll give a few allocated in different contexts objects - * the same tag. Since tag-based KASAN is meant to be used a probabilistic - * bug-detection debug feature, this doesn't have significant negative impact. - * - * Ideally the tags use strong randomness to prevent any attempts to predict - * them during explicit exploit attempts. But strong randomness is expensive, - * and we did an intentional trade-off to use a PRNG. This non-atomic RMW - * sequence has in fact positive effect, since interrupts that randomly skew - * PRNG at unpredictable points do only good. - */ -u8 random_tag(void) -{ - u32 state = this_cpu_read(prng_state); - - state = 1664525 * state + 1013904223; - this_cpu_write(prng_state, state); - - return (u8)(state % (KASAN_TAG_MAX + 1)); -} - -void *kasan_reset_tag(const void *addr) -{ - return reset_tag(addr); -} - -bool check_memory_region(unsigned long addr, size_t size, bool write, - unsigned long ret_ip) -{ - u8 tag; - u8 *shadow_first, *shadow_last, *shadow; - void *untagged_addr; - - if (unlikely(size == 0)) - return true; - - if (unlikely(addr + size < addr)) - return !kasan_report(addr, size, write, ret_ip); - - tag = get_tag((const void *)addr); - - /* - * Ignore accesses for pointers tagged with 0xff (native kernel - * pointer tag) to suppress false positives caused by kmap. - * - * Some kernel code was written to account for archs that don't keep - * high memory mapped all the time, but rather map and unmap particular - * pages when needed. Instead of storing a pointer to the kernel memory, - * this code saves the address of the page structure and offset within - * that page for later use. Those pages are then mapped and unmapped - * with kmap/kunmap when necessary and virt_to_page is used to get the - * virtual address of the page. For arm64 (that keeps the high memory - * mapped all the time), kmap is turned into a page_address call. - - * The issue is that with use of the page_address + virt_to_page - * sequence the top byte value of the original pointer gets lost (gets - * set to KASAN_TAG_KERNEL (0xFF)). - */ - if (tag == KASAN_TAG_KERNEL) - return true; - - untagged_addr = reset_tag((const void *)addr); - if (unlikely(untagged_addr < - kasan_shadow_to_mem((void *)KASAN_SHADOW_START))) { - return !kasan_report(addr, size, write, ret_ip); - } - shadow_first = kasan_mem_to_shadow(untagged_addr); - shadow_last = kasan_mem_to_shadow(untagged_addr + size - 1); - for (shadow = shadow_first; shadow <= shadow_last; shadow++) { - if (*shadow != tag) { - return !kasan_report(addr, size, write, ret_ip); - } - } - - return true; -} - -#define DEFINE_HWASAN_LOAD_STORE(size) \ - void __hwasan_load##size##_noabort(unsigned long addr) \ - { \ - check_memory_region(addr, size, false, _RET_IP_); \ - } \ - EXPORT_SYMBOL(__hwasan_load##size##_noabort); \ - void __hwasan_store##size##_noabort(unsigned long addr) \ - { \ - check_memory_region(addr, size, true, _RET_IP_); \ - } \ - EXPORT_SYMBOL(__hwasan_store##size##_noabort) - -DEFINE_HWASAN_LOAD_STORE(1); -DEFINE_HWASAN_LOAD_STORE(2); -DEFINE_HWASAN_LOAD_STORE(4); -DEFINE_HWASAN_LOAD_STORE(8); -DEFINE_HWASAN_LOAD_STORE(16); - -void __hwasan_loadN_noabort(unsigned long addr, unsigned long size) -{ - check_memory_region(addr, size, false, _RET_IP_); -} -EXPORT_SYMBOL(__hwasan_loadN_noabort); - -void __hwasan_storeN_noabort(unsigned long addr, unsigned long size) -{ - check_memory_region(addr, size, true, _RET_IP_); -} -EXPORT_SYMBOL(__hwasan_storeN_noabort); - -void __hwasan_tag_memory(unsigned long addr, u8 tag, unsigned long size) -{ - poison_range((void *)addr, size, tag); -} -EXPORT_SYMBOL(__hwasan_tag_memory); - -void kasan_set_free_info(struct kmem_cache *cache, - void *object, u8 tag) -{ - struct kasan_alloc_meta *alloc_meta; - u8 idx = 0; - - alloc_meta = get_alloc_info(cache, object); - -#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY - idx = alloc_meta->free_track_idx; - alloc_meta->free_pointer_tag[idx] = tag; - alloc_meta->free_track_idx = (idx + 1) % KASAN_NR_FREE_STACKS; -#endif - - kasan_set_track(&alloc_meta->free_track[idx], GFP_NOWAIT); -} - -struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, - void *object, u8 tag) -{ - struct kasan_alloc_meta *alloc_meta; - int i = 0; - - alloc_meta = get_alloc_info(cache, object); - -#ifdef CONFIG_KASAN_SW_TAGS_IDENTIFY - for (i = 0; i < KASAN_NR_FREE_STACKS; i++) { - if (alloc_meta->free_pointer_tag[i] == tag) - break; - } - if (i == KASAN_NR_FREE_STACKS) - i = alloc_meta->free_track_idx; -#endif - - return &alloc_meta->free_track[i]; -} |