From 0fd379253691e7bb7c0285a7b87525e1ff6e2fd2 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 24 Feb 2021 12:05:13 -0800 Subject: kasan: clean up comments in tests Clarify and update comments in KASAN tests. Link: https://linux-review.googlesource.com/id/I6c816c51fa1e0eb7aa3dead6bda1f339d2af46c8 Link: https://lkml.kernel.org/r/ba6db104d53ae0e3796f80ef395f6873c1c1282f.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 59 ++++++++++++++++++++++++++++++++++---------------------- 1 file changed, 36 insertions(+), 23 deletions(-) (limited to 'lib/test_kasan.c') diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 2947274cc2d3..6f46e27c2af7 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -28,10 +28,9 @@ #define OOB_TAG_OFF (IS_ENABLED(CONFIG_KASAN_GENERIC) ? 0 : KASAN_GRANULE_SIZE) /* - * We assign some test results to these globals to make sure the tests - * are not eliminated as dead code. + * Some tests use these global variables to store return values from function + * calls that could otherwise be eliminated by the compiler as dead code. */ - void *kasan_ptr_result; int kasan_int_result; @@ -39,14 +38,13 @@ static struct kunit_resource resource; static struct kunit_kasan_expectation fail_data; static bool multishot; +/* + * Temporarily enable multi-shot mode. Otherwise, KASAN would only report the + * first detected bug and panic the kernel if panic_on_warn is enabled. + */ static int kasan_test_init(struct kunit *test) { - /* - * Temporarily enable multi-shot mode and set panic_on_warn=0. - * Otherwise, we'd only get a report for the first case. - */ multishot = kasan_save_enable_multi_shot(); - return 0; } @@ -56,12 +54,12 @@ static void kasan_test_exit(struct kunit *test) } /** - * KUNIT_EXPECT_KASAN_FAIL() - Causes a test failure when the expression does - * not cause a KASAN error. This uses a KUnit resource named "kasan_data." Do - * Do not use this name for a KUnit resource outside here. - * + * KUNIT_EXPECT_KASAN_FAIL() - check that the executed expression produces a + * KASAN report; causes a test failure otherwise. This relies on a KUnit + * resource named "kasan_data". Do not use this name for KUnit resources + * outside of KASAN tests. */ -#define KUNIT_EXPECT_KASAN_FAIL(test, condition) do { \ +#define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \ fail_data.report_expected = true; \ fail_data.report_found = false; \ kunit_add_named_resource(test, \ @@ -69,7 +67,7 @@ static void kasan_test_exit(struct kunit *test) NULL, \ &resource, \ "kasan_data", &fail_data); \ - condition; \ + expression; \ KUNIT_EXPECT_EQ(test, \ fail_data.report_expected, \ fail_data.report_found); \ @@ -121,7 +119,8 @@ static void kmalloc_pagealloc_oob_right(struct kunit *test) return; } - /* Allocate a chunk that does not fit into a SLUB cache to trigger + /* + * Allocate a chunk that does not fit into a SLUB cache to trigger * the page allocator fallback. */ ptr = kmalloc(size, GFP_KERNEL); @@ -168,7 +167,9 @@ static void kmalloc_large_oob_right(struct kunit *test) { char *ptr; size_t size = KMALLOC_MAX_CACHE_SIZE - 256; - /* Allocate a chunk that is large enough, but still fits into a slab + + /* + * Allocate a chunk that is large enough, but still fits into a slab * and does not trigger the page allocator fallback in SLUB. */ ptr = kmalloc(size, GFP_KERNEL); @@ -469,10 +470,13 @@ static void ksize_unpoisons_memory(struct kunit *test) ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); real_size = ksize(ptr); - /* This access doesn't trigger an error. */ + + /* This access shouldn't trigger a KASAN report. */ ptr[size] = 'x'; - /* This one does. */ + + /* This one must. */ KUNIT_EXPECT_KASAN_FAIL(test, ptr[real_size] = 'y'); + kfree(ptr); } @@ -568,7 +572,7 @@ static void kmem_cache_invalid_free(struct kunit *test) return; } - /* Trigger invalid free, the object doesn't get freed */ + /* Trigger invalid free, the object doesn't get freed. */ KUNIT_EXPECT_KASAN_FAIL(test, kmem_cache_free(cache, p + 1)); /* @@ -585,7 +589,10 @@ static void kasan_memchr(struct kunit *test) char *ptr; size_t size = 24; - /* See https://bugzilla.kernel.org/show_bug.cgi?id=206337 */ + /* + * str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT. + * See https://bugzilla.kernel.org/show_bug.cgi?id=206337 for details. + */ if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { kunit_info(test, "str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT"); @@ -610,7 +617,10 @@ static void kasan_memcmp(struct kunit *test) size_t size = 24; int arr[9]; - /* See https://bugzilla.kernel.org/show_bug.cgi?id=206337 */ + /* + * str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT. + * See https://bugzilla.kernel.org/show_bug.cgi?id=206337 for details. + */ if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { kunit_info(test, "str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT"); @@ -634,7 +644,10 @@ static void kasan_strings(struct kunit *test) char *ptr; size_t size = 24; - /* See https://bugzilla.kernel.org/show_bug.cgi?id=206337 */ + /* + * str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT. + * See https://bugzilla.kernel.org/show_bug.cgi?id=206337 for details. + */ if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { kunit_info(test, "str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT"); @@ -706,7 +719,7 @@ static void kasan_bitops_generic(struct kunit *test) } /* - * Allocate 1 more byte, which causes kzalloc to round up to 16-bytes; + * Allocate 1 more byte, which causes kzalloc to round up to 16 bytes; * this way we do not actually corrupt other memory. */ bits = kzalloc(sizeof(*bits) + 1, GFP_KERNEL); -- cgit v1.2.3 From da17e377723f50c7acd019e39cfeeca342415714 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 24 Feb 2021 12:05:17 -0800 Subject: kasan: add macros to simplify checking test constraints Some KASAN tests require specific kernel configs to be enabled. Instead of copy-pasting the checks for these configs add a few helper macros and use them. Link: https://linux-review.googlesource.com/id/I237484a7fddfedf4a4aae9cc61ecbcdbe85a0a63 Link: https://lkml.kernel.org/r/6a0fcdb9676b7e869cfc415893ede12d916c246c.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Suggested-by: Alexander Potapenko Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 101 +++++++++++++++++-------------------------------------- 1 file changed, 31 insertions(+), 70 deletions(-) (limited to 'lib/test_kasan.c') diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 6f46e27c2af7..714ea27fcc3e 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -73,6 +73,20 @@ static void kasan_test_exit(struct kunit *test) fail_data.report_found); \ } while (0) +#define KASAN_TEST_NEEDS_CONFIG_ON(test, config) do { \ + if (!IS_ENABLED(config)) { \ + kunit_info((test), "skipping, " #config " required"); \ + return; \ + } \ +} while (0) + +#define KASAN_TEST_NEEDS_CONFIG_OFF(test, config) do { \ + if (IS_ENABLED(config)) { \ + kunit_info((test), "skipping, " #config " enabled"); \ + return; \ + } \ +} while (0) + static void kmalloc_oob_right(struct kunit *test) { char *ptr; @@ -114,10 +128,7 @@ static void kmalloc_pagealloc_oob_right(struct kunit *test) char *ptr; size_t size = KMALLOC_MAX_CACHE_SIZE + 10; - if (!IS_ENABLED(CONFIG_SLUB)) { - kunit_info(test, "CONFIG_SLUB is not enabled."); - return; - } + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_SLUB); /* * Allocate a chunk that does not fit into a SLUB cache to trigger @@ -135,10 +146,7 @@ static void kmalloc_pagealloc_uaf(struct kunit *test) char *ptr; size_t size = KMALLOC_MAX_CACHE_SIZE + 10; - if (!IS_ENABLED(CONFIG_SLUB)) { - kunit_info(test, "CONFIG_SLUB is not enabled."); - return; - } + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_SLUB); ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); @@ -152,10 +160,7 @@ static void kmalloc_pagealloc_invalid_free(struct kunit *test) char *ptr; size_t size = KMALLOC_MAX_CACHE_SIZE + 10; - if (!IS_ENABLED(CONFIG_SLUB)) { - kunit_info(test, "CONFIG_SLUB is not enabled."); - return; - } + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_SLUB); ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); @@ -218,10 +223,7 @@ static void kmalloc_oob_16(struct kunit *test) } *ptr1, *ptr2; /* This test is specifically crafted for the generic mode. */ - if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) { - kunit_info(test, "CONFIG_KASAN_GENERIC required\n"); - return; - } + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC); ptr1 = kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1); @@ -454,10 +456,7 @@ static void kasan_global_oob(struct kunit *test) char *p = &global_array[ARRAY_SIZE(global_array) + i]; /* Only generic mode instruments globals. */ - if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) { - kunit_info(test, "CONFIG_KASAN_GENERIC required"); - return; - } + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC); KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)p); } @@ -486,10 +485,7 @@ static void kasan_stack_oob(struct kunit *test) volatile int i = OOB_TAG_OFF; char *p = &stack_array[ARRAY_SIZE(stack_array) + i]; - if (!IS_ENABLED(CONFIG_KASAN_STACK)) { - kunit_info(test, "CONFIG_KASAN_STACK is not enabled"); - return; - } + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_STACK); KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)p); } @@ -501,15 +497,8 @@ static void kasan_alloca_oob_left(struct kunit *test) char *p = alloca_array - 1; /* Only generic mode instruments dynamic allocas. */ - if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) { - kunit_info(test, "CONFIG_KASAN_GENERIC required"); - return; - } - - if (!IS_ENABLED(CONFIG_KASAN_STACK)) { - kunit_info(test, "CONFIG_KASAN_STACK is not enabled"); - return; - } + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC); + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_STACK); KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)p); } @@ -521,15 +510,8 @@ static void kasan_alloca_oob_right(struct kunit *test) char *p = alloca_array + i; /* Only generic mode instruments dynamic allocas. */ - if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) { - kunit_info(test, "CONFIG_KASAN_GENERIC required"); - return; - } - - if (!IS_ENABLED(CONFIG_KASAN_STACK)) { - kunit_info(test, "CONFIG_KASAN_STACK is not enabled"); - return; - } + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC); + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_STACK); KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)p); } @@ -593,11 +575,7 @@ static void kasan_memchr(struct kunit *test) * str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT. * See https://bugzilla.kernel.org/show_bug.cgi?id=206337 for details. */ - if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { - kunit_info(test, - "str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT"); - return; - } + KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_AMD_MEM_ENCRYPT); if (OOB_TAG_OFF) size = round_up(size, OOB_TAG_OFF); @@ -621,11 +599,7 @@ static void kasan_memcmp(struct kunit *test) * str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT. * See https://bugzilla.kernel.org/show_bug.cgi?id=206337 for details. */ - if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { - kunit_info(test, - "str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT"); - return; - } + KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_AMD_MEM_ENCRYPT); if (OOB_TAG_OFF) size = round_up(size, OOB_TAG_OFF); @@ -648,11 +622,7 @@ static void kasan_strings(struct kunit *test) * str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT. * See https://bugzilla.kernel.org/show_bug.cgi?id=206337 for details. */ - if (IS_ENABLED(CONFIG_AMD_MEM_ENCRYPT)) { - kunit_info(test, - "str* functions are not instrumented with CONFIG_AMD_MEM_ENCRYPT"); - return; - } + KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_AMD_MEM_ENCRYPT); ptr = kmalloc(size, GFP_KERNEL | __GFP_ZERO); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); @@ -713,10 +683,7 @@ static void kasan_bitops_generic(struct kunit *test) long *bits; /* This test is specifically crafted for the generic mode. */ - if (!IS_ENABLED(CONFIG_KASAN_GENERIC)) { - kunit_info(test, "CONFIG_KASAN_GENERIC required\n"); - return; - } + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_GENERIC); /* * Allocate 1 more byte, which causes kzalloc to round up to 16 bytes; @@ -744,11 +711,8 @@ static void kasan_bitops_tags(struct kunit *test) { long *bits; - /* This test is specifically crafted for the tag-based mode. */ - if (IS_ENABLED(CONFIG_KASAN_GENERIC)) { - kunit_info(test, "CONFIG_KASAN_SW_TAGS required\n"); - return; - } + /* This test is specifically crafted for tag-based modes. */ + KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_GENERIC); /* Allocation size will be rounded to up granule size, which is 16. */ bits = kzalloc(sizeof(*bits), GFP_KERNEL); @@ -777,10 +741,7 @@ static void vmalloc_oob(struct kunit *test) { void *area; - if (!IS_ENABLED(CONFIG_KASAN_VMALLOC)) { - kunit_info(test, "CONFIG_KASAN_VMALLOC is not enabled."); - return; - } + KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_KASAN_VMALLOC); /* * We have to be careful not to hit the guard page. -- cgit v1.2.3 From 573a48092313dec7b254d9dbcc2db62167f00456 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 24 Feb 2021 12:05:21 -0800 Subject: 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.com Signed-off-by: Andrey Konovalov Signed-off-by: Arnd Bergmann Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 92 +++++++++++++++++++++++++++++++++++++++++++++++++++++++ mm/kasan/kasan.h | 6 ++++ mm/kasan/shadow.c | 1 + 3 files changed, 99 insertions(+) (limited to 'lib/test_kasan.c') diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 714ea27fcc3e..c344fe506ffc 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -754,6 +755,94 @@ static void vmalloc_oob(struct kunit *test) 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[] = { KUNIT_CASE(kmalloc_oob_right), KUNIT_CASE(kmalloc_oob_left), @@ -793,6 +882,9 @@ static struct kunit_case kasan_kunit_test_cases[] = { KUNIT_CASE(kasan_bitops_tags), KUNIT_CASE(kmalloc_double_kzfree), KUNIT_CASE(vmalloc_oob), + KUNIT_CASE(match_all_not_assigned), + KUNIT_CASE(match_all_ptr_tag), + KUNIT_CASE(match_all_mem_tag), {} }; diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 3810e75b8eea..12932186a7f9 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -36,6 +36,12 @@ extern bool kasan_flag_panic __ro_after_init; #define KASAN_TAG_INVALID 0xFE /* inaccessible memory tag */ #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 #define KASAN_FREE_PAGE 0xFF /* page was freed */ #define KASAN_PAGE_REDZONE 0xFE /* redzone for kmalloc_large allocations */ diff --git a/mm/kasan/shadow.c b/mm/kasan/shadow.c index 38958eb0d653..80adc85d0393 100644 --- a/mm/kasan/shadow.c +++ b/mm/kasan/shadow.c @@ -89,6 +89,7 @@ void kasan_poison(const void *address, size_t size, u8 value) __memset(shadow_start, value, shadow_end - shadow_start); } +EXPORT_SYMBOL(kasan_poison); void kasan_unpoison(const void *address, size_t size) { -- cgit v1.2.3 From f05842cfb9ae25b5e78c618429c4716d9e4d5fc8 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 24 Feb 2021 12:05:26 -0800 Subject: kasan, arm64: allow using KUnit tests with HW_TAGS mode On a high level, this patch allows running KUnit KASAN tests with the hardware tag-based KASAN mode. Internally, this change reenables tag checking at the end of each KASAN test that triggers a tag fault and leads to tag checking being disabled. Also simplify is_write calculation in report_tag_fault. With this patch KASAN tests are still failing for the hardware tag-based mode; fixes come in the next few patches. [andreyknvl@google.com: export HW_TAGS symbols for KUnit tests] Link: https://lkml.kernel.org/r/e7eeb252da408b08f0c81b950a55fb852f92000b.1613155970.git.andreyknvl@google.com Link: https://linux-review.googlesource.com/id/Id94dc9eccd33b23cda4950be408c27f879e474c8 Link: https://lkml.kernel.org/r/51b23112cf3fd62b8f8e9df81026fa2b15870501.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Catalin Marinas Reviewed-by: Vincenzo Frascino Cc: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Marco Elver Cc: Peter Collingbourne Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/arm64/include/asm/memory.h | 1 + arch/arm64/include/asm/mte-kasan.h | 12 +++++++++++ arch/arm64/kernel/mte.c | 12 +++++++++++ arch/arm64/mm/fault.c | 20 ++++++++++++------ lib/Kconfig.kasan | 4 ++-- lib/test_kasan.c | 42 ++++++++++++++++++++++++++------------ mm/kasan/hw_tags.c | 16 +++++++++++++++ mm/kasan/kasan.h | 21 +++++++++++++++++++ 8 files changed, 107 insertions(+), 21 deletions(-) (limited to 'lib/test_kasan.c') diff --git a/arch/arm64/include/asm/memory.h b/arch/arm64/include/asm/memory.h index bc09af26c1b8..c759faf7a1ff 100644 --- a/arch/arm64/include/asm/memory.h +++ b/arch/arm64/include/asm/memory.h @@ -244,6 +244,7 @@ static inline const void *__tag_set(const void *addr, u8 tag) #ifdef CONFIG_KASAN_HW_TAGS #define arch_enable_tagging() mte_enable_kernel() +#define arch_set_tagging_report_once(state) mte_set_report_once(state) #define arch_init_tags(max_tag) mte_init_tags(max_tag) #define arch_get_random_tag() mte_get_random_tag() #define arch_get_mem_tag(addr) mte_get_mem_tag(addr) diff --git a/arch/arm64/include/asm/mte-kasan.h b/arch/arm64/include/asm/mte-kasan.h index 26349a4b5e2e..3748d5bb88c0 100644 --- a/arch/arm64/include/asm/mte-kasan.h +++ b/arch/arm64/include/asm/mte-kasan.h @@ -32,6 +32,9 @@ void *mte_set_mem_tag_range(void *addr, size_t size, u8 tag); void mte_enable_kernel(void); void mte_init_tags(u64 max_tag); +void mte_set_report_once(bool state); +bool mte_report_once(void); + #else /* CONFIG_ARM64_MTE */ static inline u8 mte_get_ptr_tag(void *ptr) @@ -60,6 +63,15 @@ static inline void mte_init_tags(u64 max_tag) { } +static inline void mte_set_report_once(bool state) +{ +} + +static inline bool mte_report_once(void) +{ + return false; +} + #endif /* CONFIG_ARM64_MTE */ #endif /* __ASSEMBLY__ */ diff --git a/arch/arm64/kernel/mte.c b/arch/arm64/kernel/mte.c index 80b62fe49dcf..2cfc850809ce 100644 --- a/arch/arm64/kernel/mte.c +++ b/arch/arm64/kernel/mte.c @@ -25,6 +25,8 @@ u64 gcr_kernel_excl __ro_after_init; +static bool report_fault_once = true; + static void mte_sync_page_tags(struct page *page, pte_t *ptep, bool check_swap) { pte_t old_pte = READ_ONCE(*ptep); @@ -158,6 +160,16 @@ void mte_enable_kernel(void) isb(); } +void mte_set_report_once(bool state) +{ + WRITE_ONCE(report_fault_once, state); +} + +bool mte_report_once(void) +{ + return READ_ONCE(report_fault_once); +} + static void update_sctlr_el1_tcf0(u64 tcf0) { /* ISB required for the kernel uaccess routines */ diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 2e339f0bd958..dc9f96442edc 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -302,12 +302,24 @@ static void die_kernel_fault(const char *msg, unsigned long addr, static void report_tag_fault(unsigned long addr, unsigned int esr, struct pt_regs *regs) { - bool is_write = ((esr & ESR_ELx_WNR) >> ESR_ELx_WNR_SHIFT) != 0; + static bool reported; + bool is_write; + + if (READ_ONCE(reported)) + return; + + /* + * This is used for KASAN tests and assumes that no MTE faults + * happened before running the tests. + */ + if (mte_report_once()) + WRITE_ONCE(reported, true); /* * SAS bits aren't set for all faults reported in EL1, so we can't * find out access size. */ + is_write = !!(esr & ESR_ELx_WNR); kasan_report(addr, 0, is_write, regs->pc); } #else @@ -319,12 +331,8 @@ static inline void report_tag_fault(unsigned long addr, unsigned int esr, static void do_tag_recovery(unsigned long addr, unsigned int esr, struct pt_regs *regs) { - static bool reported; - if (!READ_ONCE(reported)) { - report_tag_fault(addr, esr, regs); - WRITE_ONCE(reported, true); - } + report_tag_fault(addr, esr, regs); /* * Disable MTE Tag Checking on the local CPU for the current EL. diff --git a/lib/Kconfig.kasan b/lib/Kconfig.kasan index f5fa4ba126bf..3091432acb0a 100644 --- a/lib/Kconfig.kasan +++ b/lib/Kconfig.kasan @@ -190,11 +190,11 @@ config KASAN_KUNIT_TEST kernel debugging features like KASAN. For more information on KUnit and unit tests in general, please refer - to the KUnit documentation in Documentation/dev-tools/kunit + to the KUnit documentation in Documentation/dev-tools/kunit. config TEST_KASAN_MODULE tristate "KUnit-incompatible tests of KASAN bug detection capabilities" - depends on m && KASAN + depends on m && KASAN && !KASAN_HW_TAGS help This is a part of the KASAN test suite that is incompatible with KUnit. Currently includes tests that do bad copy_from/to_user diff --git a/lib/test_kasan.c b/lib/test_kasan.c index c344fe506ffc..502709db41c0 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -41,16 +41,20 @@ static bool multishot; /* * Temporarily enable multi-shot mode. Otherwise, KASAN would only report the - * first detected bug and panic the kernel if panic_on_warn is enabled. + * first detected bug and panic the kernel if panic_on_warn is enabled. For + * hardware tag-based KASAN also allow tag checking to be reenabled for each + * test, see the comment for KUNIT_EXPECT_KASAN_FAIL(). */ static int kasan_test_init(struct kunit *test) { multishot = kasan_save_enable_multi_shot(); + kasan_set_tagging_report_once(false); return 0; } static void kasan_test_exit(struct kunit *test) { + kasan_set_tagging_report_once(true); kasan_restore_multi_shot(multishot); } @@ -59,19 +63,31 @@ static void kasan_test_exit(struct kunit *test) * KASAN report; causes a test failure otherwise. This relies on a KUnit * resource named "kasan_data". Do not use this name for KUnit resources * outside of KASAN tests. + * + * For hardware tag-based KASAN, when a tag fault happens, tag checking is + * normally auto-disabled. When this happens, this test handler reenables + * tag checking. As tag checking can be only disabled or enabled per CPU, this + * handler disables migration (preemption). */ -#define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \ - fail_data.report_expected = true; \ - fail_data.report_found = false; \ - kunit_add_named_resource(test, \ - NULL, \ - NULL, \ - &resource, \ - "kasan_data", &fail_data); \ - expression; \ - KUNIT_EXPECT_EQ(test, \ - fail_data.report_expected, \ - fail_data.report_found); \ +#define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \ + if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) \ + migrate_disable(); \ + fail_data.report_expected = true; \ + fail_data.report_found = false; \ + kunit_add_named_resource(test, \ + NULL, \ + NULL, \ + &resource, \ + "kasan_data", &fail_data); \ + expression; \ + KUNIT_EXPECT_EQ(test, \ + fail_data.report_expected, \ + fail_data.report_found); \ + if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) { \ + if (fail_data.report_found) \ + kasan_enable_tagging(); \ + migrate_enable(); \ + } \ } while (0) #define KASAN_TEST_NEEDS_CONFIG_ON(test, config) do { \ diff --git a/mm/kasan/hw_tags.c b/mm/kasan/hw_tags.c index d558799b25b3..b31aeef505dd 100644 --- a/mm/kasan/hw_tags.c +++ b/mm/kasan/hw_tags.c @@ -185,3 +185,19 @@ struct kasan_track *kasan_get_free_track(struct kmem_cache *cache, return &alloc_meta->free_track[0]; } + +#if IS_ENABLED(CONFIG_KASAN_KUNIT_TEST) + +void kasan_set_tagging_report_once(bool state) +{ + hw_set_tagging_report_once(state); +} +EXPORT_SYMBOL_GPL(kasan_set_tagging_report_once); + +void kasan_enable_tagging(void) +{ + hw_enable_tagging(); +} +EXPORT_SYMBOL_GPL(kasan_enable_tagging); + +#endif diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 12932186a7f9..1298b79f9518 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -280,6 +280,9 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag) #ifndef arch_init_tags #define arch_init_tags(max_tag) #endif +#ifndef arch_set_tagging_report_once +#define arch_set_tagging_report_once(state) +#endif #ifndef arch_get_random_tag #define arch_get_random_tag() (0xFF) #endif @@ -292,12 +295,30 @@ static inline const void *arch_kasan_set_tag(const void *addr, u8 tag) #define hw_enable_tagging() arch_enable_tagging() #define hw_init_tags(max_tag) arch_init_tags(max_tag) +#define hw_set_tagging_report_once(state) arch_set_tagging_report_once(state) #define hw_get_random_tag() arch_get_random_tag() #define hw_get_mem_tag(addr) arch_get_mem_tag(addr) #define hw_set_mem_tag_range(addr, size, tag) arch_set_mem_tag_range((addr), (size), (tag)) +#else /* CONFIG_KASAN_HW_TAGS */ + +#define hw_enable_tagging() +#define hw_set_tagging_report_once(state) + #endif /* CONFIG_KASAN_HW_TAGS */ +#if defined(CONFIG_KASAN_HW_TAGS) && IS_ENABLED(CONFIG_KASAN_KUNIT_TEST) + +void kasan_set_tagging_report_once(bool state); +void kasan_enable_tagging(void); + +#else /* CONFIG_KASAN_HW_TAGS || CONFIG_KASAN_KUNIT_TEST */ + +static inline void kasan_set_tagging_report_once(bool state) { } +static inline void kasan_enable_tagging(void) { } + +#endif /* CONFIG_KASAN_HW_TAGS || CONFIG_KASAN_KUNIT_TEST */ + #ifdef CONFIG_KASAN_SW_TAGS u8 kasan_random_tag(void); #elif defined(CONFIG_KASAN_HW_TAGS) -- cgit v1.2.3 From 2e4bde6a1e3a3feb8511685b8c97be668728eefb Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 24 Feb 2021 12:05:34 -0800 Subject: kasan: add compiler barriers to KUNIT_EXPECT_KASAN_FAIL It might not be obvious to the compiler that the expression must be executed between writing and reading to fail_data. In this case, the compiler might reorder or optimize away some of the accesses, and the tests will fail. Add compiler barriers around the expression in KUNIT_EXPECT_KASAN_FAIL and use READ/WRITE_ONCE() for accessing fail_data fields. Link: https://linux-review.googlesource.com/id/I046079f48641a1d36fe627fc8827a9249102fd50 Link: https://lkml.kernel.org/r/6f11596f367d8ae8f71d800351e9a5d91eda19f6.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 17 ++++++++++++----- mm/kasan/report.c | 2 +- 2 files changed, 13 insertions(+), 6 deletions(-) (limited to 'lib/test_kasan.c') diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 502709db41c0..603fd7937b94 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -68,23 +68,30 @@ static void kasan_test_exit(struct kunit *test) * normally auto-disabled. When this happens, this test handler reenables * tag checking. As tag checking can be only disabled or enabled per CPU, this * handler disables migration (preemption). + * + * Since the compiler doesn't see that the expression can change the fail_data + * fields, it can reorder or optimize away the accesses to those fields. + * Use READ/WRITE_ONCE() for the accesses and compiler barriers around the + * expression to prevent that. */ #define KUNIT_EXPECT_KASAN_FAIL(test, expression) do { \ if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) \ migrate_disable(); \ - fail_data.report_expected = true; \ - fail_data.report_found = false; \ + WRITE_ONCE(fail_data.report_expected, true); \ + WRITE_ONCE(fail_data.report_found, false); \ kunit_add_named_resource(test, \ NULL, \ NULL, \ &resource, \ "kasan_data", &fail_data); \ + barrier(); \ expression; \ + barrier(); \ KUNIT_EXPECT_EQ(test, \ - fail_data.report_expected, \ - fail_data.report_found); \ + READ_ONCE(fail_data.report_expected), \ + READ_ONCE(fail_data.report_found)); \ if (IS_ENABLED(CONFIG_KASAN_HW_TAGS)) { \ - if (fail_data.report_found) \ + if (READ_ONCE(fail_data.report_found)) \ kasan_enable_tagging(); \ migrate_enable(); \ } \ diff --git a/mm/kasan/report.c b/mm/kasan/report.c index e93d7973792e..234f35a84f19 100644 --- a/mm/kasan/report.c +++ b/mm/kasan/report.c @@ -331,7 +331,7 @@ static void kasan_update_kunit_status(struct kunit *cur_test) } kasan_data = (struct kunit_kasan_expectation *)resource->data; - kasan_data->report_found = true; + WRITE_ONCE(kasan_data->report_found, true); kunit_put_resource(resource); } #endif /* IS_ENABLED(CONFIG_KUNIT) */ -- cgit v1.2.3 From 1b1df4c4e2576f6b9c5b1f5f1fc9435e3f6c6b47 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 24 Feb 2021 12:05:38 -0800 Subject: kasan: adapt kmalloc_uaf2 test to HW_TAGS mode In the kmalloc_uaf2() test, the pointers to the two allocated memory blocks might happen to be the same, and the test will fail. With the software tag-based mode, the probability of the that is 1/254, so it's hard to observe the failure. For the hardware tag-based mode though, the probablity is 1/14, which is quite noticable. Allow up to 16 attempts at generating different tags for the tag-based modes. Link: https://linux-review.googlesource.com/id/Ibfa458ef2804ff465d8eb07434a300bf36388d55 Link: https://lkml.kernel.org/r/9cd5cf2f633dcbf55cab801cd26845d2b075cec7.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 11 +++++++++++ 1 file changed, 11 insertions(+) (limited to 'lib/test_kasan.c') diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 603fd7937b94..9a227d7e06d6 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -382,7 +382,9 @@ static void kmalloc_uaf2(struct kunit *test) { char *ptr1, *ptr2; size_t size = 43; + int counter = 0; +again: ptr1 = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1); @@ -391,6 +393,15 @@ static void kmalloc_uaf2(struct kunit *test) ptr2 = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2); + /* + * For tag-based KASAN ptr1 and ptr2 tags might happen to be the same. + * Allow up to 16 attempts at generating different tags. + */ + if (!IS_ENABLED(CONFIG_KASAN_GENERIC) && ptr1 == ptr2 && counter++ < 16) { + kfree(ptr2); + goto again; + } + KUNIT_EXPECT_KASAN_FAIL(test, ptr1[40] = 'x'); KUNIT_EXPECT_PTR_NE(test, ptr1, ptr2); -- cgit v1.2.3 From e66e1799a76621003e5b04c9c057826a2152e103 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 24 Feb 2021 12:05:42 -0800 Subject: kasan: fix memory corruption in kasan_bitops_tags test Since the hardware tag-based KASAN mode might not have a redzone that comes after an allocated object (when kasan.mode=prod is enabled), the kasan_bitops_tags() test ends up corrupting the next object in memory. Change the test so it always accesses the redzone that lies within the allocated object's boundaries. Link: https://linux-review.googlesource.com/id/I67f51d1ee48f0a8d0fe2658c2a39e4879fe0832a Link: https://lkml.kernel.org/r/7d452ce4ae35bb1988d2c9244dfea56cf2cc9315.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'lib/test_kasan.c') diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 9a227d7e06d6..e59f185b8075 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -749,13 +749,13 @@ static void kasan_bitops_tags(struct kunit *test) /* This test is specifically crafted for tag-based modes. */ KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_GENERIC); - /* Allocation size will be rounded to up granule size, which is 16. */ - bits = kzalloc(sizeof(*bits), GFP_KERNEL); + /* kmalloc-64 cache will be used and the last 16 bytes will be the redzone. */ + bits = kzalloc(48, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bits); - /* Do the accesses past the 16 allocated bytes. */ - kasan_bitops_modify(test, BITS_PER_LONG, &bits[1]); - kasan_bitops_test_and_modify(test, BITS_PER_LONG + BITS_PER_BYTE, &bits[1]); + /* Do the accesses past the 48 allocated bytes, but within the redone. */ + kasan_bitops_modify(test, BITS_PER_LONG, (void *)bits + 48); + kasan_bitops_test_and_modify(test, BITS_PER_LONG + BITS_PER_BYTE, (void *)bits + 48); kfree(bits); } -- cgit v1.2.3 From 611806b4bf8dd97a4f3d73f5cf3c2c7730c51eb2 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 24 Feb 2021 12:05:50 -0800 Subject: kasan: fix bug detection via ksize for HW_TAGS mode The currently existing kasan_check_read/write() annotations are intended to be used for kernel modules that have KASAN compiler instrumentation disabled. Thus, they are only relevant for the software KASAN modes that rely on compiler instrumentation. However there's another use case for these annotations: ksize() checks that the object passed to it is indeed accessible before unpoisoning the whole object. This is currently done via __kasan_check_read(), which is compiled away for the hardware tag-based mode that doesn't rely on compiler instrumentation. This leads to KASAN missing detecting some memory corruptions. Provide another annotation called kasan_check_byte() that is available for all KASAN modes. As the implementation rename and reuse kasan_check_invalid_free(). Use this new annotation in ksize(). To avoid having ksize() as the top frame in the reported stack trace pass _RET_IP_ to __kasan_check_byte(). Also add a new ksize_uaf() test that checks that a use-after-free is detected via ksize() itself, and via plain accesses that happen later. Link: https://linux-review.googlesource.com/id/Iaabf771881d0f9ce1b969f2a62938e99d3308ec5 Link: https://lkml.kernel.org/r/f32ad74a60b28d8402482a38476f02bb7600f620.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/kasan-checks.h | 6 ++++++ include/linux/kasan.h | 17 +++++++++++++++++ lib/test_kasan.c | 20 ++++++++++++++++++++ mm/kasan/common.c | 11 ++++++++++- mm/kasan/generic.c | 4 ++-- mm/kasan/kasan.h | 10 +++++----- mm/kasan/sw_tags.c | 6 +++--- mm/slab_common.c | 16 +++++++++------- 8 files changed, 72 insertions(+), 18 deletions(-) (limited to 'lib/test_kasan.c') diff --git a/include/linux/kasan-checks.h b/include/linux/kasan-checks.h index ca5e89fb10d3..3d6d22a25bdc 100644 --- a/include/linux/kasan-checks.h +++ b/include/linux/kasan-checks.h @@ -4,6 +4,12 @@ #include +/* + * The annotations present in this file are only relevant for the software + * KASAN modes that rely on compiler instrumentation, and will be optimized + * away for the hardware tag-based KASAN mode. Use kasan_check_byte() instead. + */ + /* * __kasan_check_*: Always available when KASAN is enabled. This may be used * even in compilation units that selectively disable KASAN, but must use KASAN diff --git a/include/linux/kasan.h b/include/linux/kasan.h index a7254186558a..7eaf2d9effb4 100644 --- a/include/linux/kasan.h +++ b/include/linux/kasan.h @@ -246,6 +246,19 @@ static __always_inline void kasan_kfree_large(void *ptr) __kasan_kfree_large(ptr, _RET_IP_); } +/* + * Unlike kasan_check_read/write(), kasan_check_byte() is performed even for + * the hardware tag-based mode that doesn't rely on compiler instrumentation. + */ +bool __kasan_check_byte(const void *addr, unsigned long ip); +static __always_inline bool kasan_check_byte(const void *addr) +{ + if (kasan_enabled()) + return __kasan_check_byte(addr, _RET_IP_); + return true; +} + + bool kasan_save_enable_multi_shot(void); void kasan_restore_multi_shot(bool enabled); @@ -301,6 +314,10 @@ static inline void *kasan_krealloc(const void *object, size_t new_size, return (void *)object; } static inline void kasan_kfree_large(void *ptr) {} +static inline bool kasan_check_byte(const void *address) +{ + return true; +} #endif /* CONFIG_KASAN */ diff --git a/lib/test_kasan.c b/lib/test_kasan.c index e59f185b8075..3f771fabd0ec 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -496,6 +496,7 @@ static void kasan_global_oob(struct kunit *test) KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)p); } +/* Check that ksize() makes the whole object accessible. */ static void ksize_unpoisons_memory(struct kunit *test) { char *ptr; @@ -514,6 +515,24 @@ static void ksize_unpoisons_memory(struct kunit *test) kfree(ptr); } +/* + * Check that a use-after-free is detected by ksize() and via normal accesses + * after it. + */ +static void ksize_uaf(struct kunit *test) +{ + char *ptr; + int size = 128 - KASAN_GRANULE_SIZE; + + ptr = kmalloc(size, GFP_KERNEL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + kfree(ptr); + + KUNIT_EXPECT_KASAN_FAIL(test, ksize(ptr)); + KUNIT_EXPECT_KASAN_FAIL(test, kasan_int_result = *ptr); + KUNIT_EXPECT_KASAN_FAIL(test, kasan_int_result = *(ptr + size)); +} + static void kasan_stack_oob(struct kunit *test) { char stack_array[10]; @@ -907,6 +926,7 @@ static struct kunit_case kasan_kunit_test_cases[] = { KUNIT_CASE(kasan_alloca_oob_left), KUNIT_CASE(kasan_alloca_oob_right), KUNIT_CASE(ksize_unpoisons_memory), + KUNIT_CASE(ksize_uaf), KUNIT_CASE(kmem_cache_double_free), KUNIT_CASE(kmem_cache_invalid_free), KUNIT_CASE(kasan_memchr), diff --git a/mm/kasan/common.c b/mm/kasan/common.c index eedc3e0fe365..b18189ef3a92 100644 --- a/mm/kasan/common.c +++ b/mm/kasan/common.c @@ -345,7 +345,7 @@ static bool ____kasan_slab_free(struct kmem_cache *cache, void *object, if (unlikely(cache->flags & SLAB_TYPESAFE_BY_RCU)) return false; - if (kasan_check_invalid_free(tagged_object)) { + if (!kasan_byte_accessible(tagged_object)) { kasan_report_invalid_free(tagged_object, ip); return true; } @@ -490,3 +490,12 @@ void __kasan_kfree_large(void *ptr, unsigned long ip) kasan_report_invalid_free(ptr, ip); /* The object will be poisoned by kasan_free_pages(). */ } + +bool __kasan_check_byte(const void *address, unsigned long ip) +{ + if (!kasan_byte_accessible(address)) { + kasan_report((unsigned long)address, 1, false, ip); + return false; + } + return true; +} diff --git a/mm/kasan/generic.c b/mm/kasan/generic.c index acab8862dc67..3f17a1218055 100644 --- a/mm/kasan/generic.c +++ b/mm/kasan/generic.c @@ -185,11 +185,11 @@ bool kasan_check_range(unsigned long addr, size_t size, bool write, return check_region_inline(addr, size, write, ret_ip); } -bool kasan_check_invalid_free(void *addr) +bool kasan_byte_accessible(const void *addr) { s8 shadow_byte = READ_ONCE(*(s8 *)kasan_mem_to_shadow(addr)); - return shadow_byte < 0 || shadow_byte >= KASAN_GRANULE_SIZE; + return shadow_byte >= 0 && shadow_byte < KASAN_GRANULE_SIZE; } void kasan_cache_shrink(struct kmem_cache *cache) diff --git a/mm/kasan/kasan.h b/mm/kasan/kasan.h index 1298b79f9518..cc14b6e6c14c 100644 --- a/mm/kasan/kasan.h +++ b/mm/kasan/kasan.h @@ -341,20 +341,20 @@ static inline void kasan_unpoison(const void *address, size_t size) round_up(size, KASAN_GRANULE_SIZE), get_tag(address)); } -static inline bool kasan_check_invalid_free(void *addr) +static inline bool kasan_byte_accessible(const void *addr) { u8 ptr_tag = get_tag(addr); - u8 mem_tag = hw_get_mem_tag(addr); + u8 mem_tag = hw_get_mem_tag((void *)addr); - return (mem_tag == KASAN_TAG_INVALID) || - (ptr_tag != KASAN_TAG_KERNEL && ptr_tag != mem_tag); + return (mem_tag != KASAN_TAG_INVALID) && + (ptr_tag == KASAN_TAG_KERNEL || ptr_tag == mem_tag); } #else /* CONFIG_KASAN_HW_TAGS */ void kasan_poison(const void *address, size_t size, u8 value); void kasan_unpoison(const void *address, size_t size); -bool kasan_check_invalid_free(void *addr); +bool kasan_byte_accessible(const void *addr); #endif /* CONFIG_KASAN_HW_TAGS */ diff --git a/mm/kasan/sw_tags.c b/mm/kasan/sw_tags.c index cc271fceb5d5..94c2d33be333 100644 --- a/mm/kasan/sw_tags.c +++ b/mm/kasan/sw_tags.c @@ -118,13 +118,13 @@ bool kasan_check_range(unsigned long addr, size_t size, bool write, return true; } -bool kasan_check_invalid_free(void *addr) +bool kasan_byte_accessible(const void *addr) { u8 tag = get_tag(addr); u8 shadow_byte = READ_ONCE(*(u8 *)kasan_mem_to_shadow(kasan_reset_tag(addr))); - return (shadow_byte == KASAN_TAG_INVALID) || - (tag != KASAN_TAG_KERNEL && tag != shadow_byte); + return (shadow_byte != KASAN_TAG_INVALID) && + (tag == KASAN_TAG_KERNEL || tag == shadow_byte); } #define DEFINE_HWASAN_LOAD_STORE(size) \ diff --git a/mm/slab_common.c b/mm/slab_common.c index 5be7825ad3ce..7c8298c17145 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -1218,19 +1218,21 @@ size_t ksize(const void *objp) size_t size; /* - * We need to check that the pointed to object is valid, and only then - * unpoison the shadow memory below. We use __kasan_check_read(), to - * generate a more useful report at the time ksize() is called (rather - * than later where behaviour is undefined due to potential - * use-after-free or double-free). + * We need to first check that the pointer to the object is valid, and + * only then unpoison the memory. The report printed from ksize() is + * more useful, then when it's printed later when the behaviour could + * be undefined due to a potential use-after-free or double-free. * - * If the pointed to memory is invalid we return 0, to avoid users of + * We use kasan_check_byte(), which is supported for the hardware + * tag-based KASAN mode, unlike kasan_check_read/write(). + * + * If the pointed to memory is invalid, we return 0 to avoid users of * ksize() writing to and potentially corrupting the memory region. * * We want to perform the check before __ksize(), to avoid potentially * crashing in __ksize() due to accessing invalid metadata. */ - if (unlikely(ZERO_OR_NULL_PTR(objp)) || !__kasan_check_read(objp, 1)) + if (unlikely(ZERO_OR_NULL_PTR(objp)) || !kasan_check_byte(objp)) return 0; size = __ksize(objp); -- cgit v1.2.3 From 858bdeb046f6dc7a79039d577d03e4d2b39272b7 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 24 Feb 2021 12:05:55 -0800 Subject: kasan: add proper page allocator tests The currently existing page allocator tests rely on kmalloc fallback with large sizes that is only present for SLUB. Add proper tests that use alloc/free_pages(). Link: https://linux-review.googlesource.com/id/Ia173d5a1b215fe6b2548d814ef0f4433cf983570 Link: https://lkml.kernel.org/r/a2648930e55ff75b8e700f2e0d905c2b55a67483.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 51 ++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 46 insertions(+), 5 deletions(-) (limited to 'lib/test_kasan.c') diff --git a/lib/test_kasan.c b/lib/test_kasan.c index 3f771fabd0ec..acbc7d54d067 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -147,6 +147,12 @@ static void kmalloc_node_oob_right(struct kunit *test) kfree(ptr); } +/* + * These kmalloc_pagealloc_* tests try allocating a memory chunk that doesn't + * fit into a slab cache and therefore is allocated via the page allocator + * fallback. Since this kind of fallback is only implemented for SLUB, these + * tests are limited to that allocator. + */ static void kmalloc_pagealloc_oob_right(struct kunit *test) { char *ptr; @@ -154,14 +160,11 @@ static void kmalloc_pagealloc_oob_right(struct kunit *test) KASAN_TEST_NEEDS_CONFIG_ON(test, CONFIG_SLUB); - /* - * Allocate a chunk that does not fit into a SLUB cache to trigger - * the page allocator fallback. - */ ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); KUNIT_EXPECT_KASAN_FAIL(test, ptr[size + OOB_TAG_OFF] = 0); + kfree(ptr); } @@ -174,8 +177,8 @@ static void kmalloc_pagealloc_uaf(struct kunit *test) ptr = kmalloc(size, GFP_KERNEL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); - kfree(ptr); + KUNIT_EXPECT_KASAN_FAIL(test, ptr[0] = 0); } @@ -192,6 +195,42 @@ static void kmalloc_pagealloc_invalid_free(struct kunit *test) KUNIT_EXPECT_KASAN_FAIL(test, kfree(ptr + 1)); } +static void pagealloc_oob_right(struct kunit *test) +{ + char *ptr; + struct page *pages; + size_t order = 4; + size_t size = (1UL << (PAGE_SHIFT + order)); + + /* + * With generic KASAN page allocations have no redzones, thus + * out-of-bounds detection is not guaranteed. + * See https://bugzilla.kernel.org/show_bug.cgi?id=210503. + */ + KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_GENERIC); + + pages = alloc_pages(GFP_KERNEL, order); + ptr = page_address(pages); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + + KUNIT_EXPECT_KASAN_FAIL(test, ptr[size] = 0); + free_pages((unsigned long)ptr, order); +} + +static void pagealloc_uaf(struct kunit *test) +{ + char *ptr; + struct page *pages; + size_t order = 4; + + pages = alloc_pages(GFP_KERNEL, order); + ptr = page_address(pages); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr); + free_pages((unsigned long)ptr, order); + + KUNIT_EXPECT_KASAN_FAIL(test, ptr[0] = 0); +} + static void kmalloc_large_oob_right(struct kunit *test) { char *ptr; @@ -903,6 +942,8 @@ static struct kunit_case kasan_kunit_test_cases[] = { KUNIT_CASE(kmalloc_pagealloc_oob_right), KUNIT_CASE(kmalloc_pagealloc_uaf), KUNIT_CASE(kmalloc_pagealloc_invalid_free), + KUNIT_CASE(pagealloc_oob_right), + KUNIT_CASE(pagealloc_uaf), KUNIT_CASE(kmalloc_large_oob_right), KUNIT_CASE(kmalloc_oob_krealloc_more), KUNIT_CASE(kmalloc_oob_krealloc_less), -- cgit v1.2.3 From 115161354d0e0af6fc07dcbbf0fc4e7574d32cd6 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 24 Feb 2021 12:05:59 -0800 Subject: kasan: add a test for kmem_cache_alloc/free_bulk Add a test for kmem_cache_alloc/free_bulk to make sure there are no false-positives when these functions are used. Link: https://linux-review.googlesource.com/id/I2a8bf797aecf81baeac61380c567308f319e263d Link: https://lkml.kernel.org/r/418122ebe4600771ac81e9ca6eab6740cf8dcfa1.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 38 +++++++++++++++++++++++++++++++++----- 1 file changed, 33 insertions(+), 5 deletions(-) (limited to 'lib/test_kasan.c') diff --git a/lib/test_kasan.c b/lib/test_kasan.c index acbc7d54d067..b04729b61d1d 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -479,10 +479,11 @@ static void kmem_cache_oob(struct kunit *test) { char *p; size_t size = 200; - struct kmem_cache *cache = kmem_cache_create("test_cache", - size, 0, - 0, NULL); + struct kmem_cache *cache; + + cache = kmem_cache_create("test_cache", size, 0, 0, NULL); KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cache); + p = kmem_cache_alloc(cache, GFP_KERNEL); if (!p) { kunit_err(test, "Allocation failed: %s\n", __func__); @@ -491,11 +492,12 @@ static void kmem_cache_oob(struct kunit *test) } KUNIT_EXPECT_KASAN_FAIL(test, *p = p[size + OOB_TAG_OFF]); + kmem_cache_free(cache, p); kmem_cache_destroy(cache); } -static void memcg_accounted_kmem_cache(struct kunit *test) +static void kmem_cache_accounted(struct kunit *test) { int i; char *p; @@ -522,6 +524,31 @@ free_cache: kmem_cache_destroy(cache); } +static void kmem_cache_bulk(struct kunit *test) +{ + struct kmem_cache *cache; + size_t size = 200; + char *p[10]; + bool ret; + int i; + + cache = kmem_cache_create("test_cache", size, 0, 0, NULL); + KUNIT_ASSERT_NOT_ERR_OR_NULL(test, cache); + + ret = kmem_cache_alloc_bulk(cache, GFP_KERNEL, ARRAY_SIZE(p), (void **)&p); + if (!ret) { + kunit_err(test, "Allocation failed: %s\n", __func__); + kmem_cache_destroy(cache); + return; + } + + for (i = 0; i < ARRAY_SIZE(p); i++) + p[i][0] = p[i][size - 1] = 42; + + kmem_cache_free_bulk(cache, ARRAY_SIZE(p), (void **)&p); + kmem_cache_destroy(cache); +} + static char global_array[10]; static void kasan_global_oob(struct kunit *test) @@ -961,7 +988,8 @@ static struct kunit_case kasan_kunit_test_cases[] = { KUNIT_CASE(kfree_via_page), KUNIT_CASE(kfree_via_phys), KUNIT_CASE(kmem_cache_oob), - KUNIT_CASE(memcg_accounted_kmem_cache), + KUNIT_CASE(kmem_cache_accounted), + KUNIT_CASE(kmem_cache_bulk), KUNIT_CASE(kasan_global_oob), KUNIT_CASE(kasan_stack_oob), KUNIT_CASE(kasan_alloca_oob_left), -- cgit v1.2.3 From d82dc3a40d12c6eea15c18d24c0bdbc887d0e7c6 Mon Sep 17 00:00:00 2001 From: Andrey Konovalov Date: Wed, 24 Feb 2021 12:06:02 -0800 Subject: kasan: don't run tests when KASAN is not enabled Don't run KASAN tests when it's disabled with kasan.mode=off to avoid corrupting kernel memory. Link: https://linux-review.googlesource.com/id/I6447af436a69a94bfc35477f6bf4e2122948355e Link: https://lkml.kernel.org/r/25bd4fb5cae7b421d806a1f33fb633edd313f0c7.1610733117.git.andreyknvl@google.com Signed-off-by: Andrey Konovalov Reviewed-by: Marco Elver Reviewed-by: Alexander Potapenko Cc: Andrey Ryabinin Cc: Branislav Rankov Cc: Catalin Marinas Cc: Dmitry Vyukov Cc: Evgenii Stepanov Cc: Kevin Brodsky Cc: Peter Collingbourne Cc: Vincenzo Frascino Cc: Will Deacon Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- lib/test_kasan.c | 5 +++++ 1 file changed, 5 insertions(+) (limited to 'lib/test_kasan.c') diff --git a/lib/test_kasan.c b/lib/test_kasan.c index b04729b61d1d..25576303897b 100644 --- a/lib/test_kasan.c +++ b/lib/test_kasan.c @@ -47,6 +47,11 @@ static bool multishot; */ static int kasan_test_init(struct kunit *test) { + if (!kasan_enabled()) { + kunit_err(test, "can't run KASAN tests with KASAN disabled"); + return -1; + } + multishot = kasan_save_enable_multi_shot(); kasan_set_tagging_report_once(false); return 0; -- cgit v1.2.3