Commit 573a4809 authored by Andrey Konovalov's avatar Andrey Konovalov Committed by Linus Torvalds

kasan: add match-all tag tests

Add 3 new tests for tag-based KASAN modes:

1. Check that match-all pointer tag is not assigned randomly.
2. Check that 0xff works as a match-all pointer tag.
3. Check that there are no match-all memory tags.

Note, that test #3 causes a significant number (255) of KASAN reports
to be printed during execution for the SW_TAGS mode.

[arnd@arndb.de: export kasan_poison]
  Link: https://lkml.kernel.org/r/20210125112831.2156212-1-arnd@kernel.org
[akpm@linux-foundation.org: s/EXPORT_SYMBOL_GPL/EXPORT_SYMBOL/, per Andrey]

Link: https://linux-review.googlesource.com/id/I78f1375efafa162b37f3abcb2c5bc2f3955dfd8e
Link: https://lkml.kernel.org/r/da841a5408e2204bf25f3b23f70540a65844e8a4.1610733117.git.andreyknvl@google.comSigned-off-by: default avatarAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
Reviewed-by: default avatarMarco Elver <elver@google.com>
Reviewed-by: default avatarAlexander Potapenko <glider@google.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: Peter Collingbourne <pcc@google.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Will Deacon <will.deacon@arm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent da17e377
...@@ -13,6 +13,7 @@ ...@@ -13,6 +13,7 @@
#include <linux/mman.h> #include <linux/mman.h>
#include <linux/module.h> #include <linux/module.h>
#include <linux/printk.h> #include <linux/printk.h>
#include <linux/random.h>
#include <linux/slab.h> #include <linux/slab.h>
#include <linux/string.h> #include <linux/string.h>
#include <linux/uaccess.h> #include <linux/uaccess.h>
...@@ -754,6 +755,94 @@ static void vmalloc_oob(struct kunit *test) ...@@ -754,6 +755,94 @@ static void vmalloc_oob(struct kunit *test)
vfree(area); vfree(area);
} }
/*
* Check that the assigned pointer tag falls within the [KASAN_TAG_MIN,
* KASAN_TAG_KERNEL) range (note: excluding the match-all tag) for tag-based
* modes.
*/
static void match_all_not_assigned(struct kunit *test)
{
char *ptr;
struct page *pages;
int i, size, order;
KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_GENERIC);
for (i = 0; i < 256; i++) {
size = (get_random_int() % 1024) + 1;
ptr = kmalloc(size, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
KUNIT_EXPECT_GE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_MIN);
KUNIT_EXPECT_LT(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL);
kfree(ptr);
}
for (i = 0; i < 256; i++) {
order = (get_random_int() % 4) + 1;
pages = alloc_pages(GFP_KERNEL, order);
ptr = page_address(pages);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
KUNIT_EXPECT_GE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_MIN);
KUNIT_EXPECT_LT(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL);
free_pages((unsigned long)ptr, order);
}
}
/* Check that 0xff works as a match-all pointer tag for tag-based modes. */
static void match_all_ptr_tag(struct kunit *test)
{
char *ptr;
u8 tag;
KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_GENERIC);
ptr = kmalloc(128, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
/* Backup the assigned tag. */
tag = get_tag(ptr);
KUNIT_EXPECT_NE(test, tag, (u8)KASAN_TAG_KERNEL);
/* Reset the tag to 0xff.*/
ptr = set_tag(ptr, KASAN_TAG_KERNEL);
/* This access shouldn't trigger a KASAN report. */
*ptr = 0;
/* Recover the pointer tag and free. */
ptr = set_tag(ptr, tag);
kfree(ptr);
}
/* Check that there are no match-all memory tags for tag-based modes. */
static void match_all_mem_tag(struct kunit *test)
{
char *ptr;
int tag;
KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_GENERIC);
ptr = kmalloc(128, GFP_KERNEL);
KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
KUNIT_EXPECT_NE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL);
/* For each possible tag value not matching the pointer tag. */
for (tag = KASAN_TAG_MIN; tag <= KASAN_TAG_KERNEL; tag++) {
if (tag == get_tag(ptr))
continue;
/* Mark the first memory granule with the chosen memory tag. */
kasan_poison(ptr, KASAN_GRANULE_SIZE, (u8)tag);
/* This access must cause a KASAN report. */
KUNIT_EXPECT_KASAN_FAIL(test, *ptr = 0);
}
/* Recover the memory tag and free. */
kasan_poison(ptr, KASAN_GRANULE_SIZE, get_tag(ptr));
kfree(ptr);
}
static struct kunit_case kasan_kunit_test_cases[] = { static struct kunit_case kasan_kunit_test_cases[] = {
KUNIT_CASE(kmalloc_oob_right), KUNIT_CASE(kmalloc_oob_right),
KUNIT_CASE(kmalloc_oob_left), KUNIT_CASE(kmalloc_oob_left),
...@@ -793,6 +882,9 @@ static struct kunit_case kasan_kunit_test_cases[] = { ...@@ -793,6 +882,9 @@ static struct kunit_case kasan_kunit_test_cases[] = {
KUNIT_CASE(kasan_bitops_tags), KUNIT_CASE(kasan_bitops_tags),
KUNIT_CASE(kmalloc_double_kzfree), KUNIT_CASE(kmalloc_double_kzfree),
KUNIT_CASE(vmalloc_oob), KUNIT_CASE(vmalloc_oob),
KUNIT_CASE(match_all_not_assigned),
KUNIT_CASE(match_all_ptr_tag),
KUNIT_CASE(match_all_mem_tag),
{} {}
}; };
......
...@@ -36,6 +36,12 @@ extern bool kasan_flag_panic __ro_after_init; ...@@ -36,6 +36,12 @@ extern bool kasan_flag_panic __ro_after_init;
#define KASAN_TAG_INVALID 0xFE /* inaccessible memory tag */ #define KASAN_TAG_INVALID 0xFE /* inaccessible memory tag */
#define KASAN_TAG_MAX 0xFD /* maximum value for random tags */ #define KASAN_TAG_MAX 0xFD /* maximum value for random tags */
#ifdef CONFIG_KASAN_HW_TAGS
#define KASAN_TAG_MIN 0xF0 /* mimimum value for random tags */
#else
#define KASAN_TAG_MIN 0x00 /* mimimum value for random tags */
#endif
#ifdef CONFIG_KASAN_GENERIC #ifdef CONFIG_KASAN_GENERIC
#define KASAN_FREE_PAGE 0xFF /* page was freed */ #define KASAN_FREE_PAGE 0xFF /* page was freed */
#define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocations */ #define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocations */
......
...@@ -89,6 +89,7 @@ void kasan_poison(const void *address, size_t size, u8 value) ...@@ -89,6 +89,7 @@ void kasan_poison(const void *address, size_t size, u8 value)
__memset(shadow_start, value, shadow_end - shadow_start); __memset(shadow_start, value, shadow_end - shadow_start);
} }
EXPORT_SYMBOL(kasan_poison);
void kasan_unpoison(const void *address, size_t size) void kasan_unpoison(const void *address, size_t size)
{ {
......
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