kasan: adopt KUNIT tests to SW_TAGS mode

Now that we have KASAN-KUNIT tests integration, it's easy to see that
some KASAN tests are not adopted to the SW_TAGS mode and are failing.

Adjust the allocation size for kasan_memchr() and kasan_memcmp() by
roung it up to OOB_TAG_OFF so the bad access ends up in a separate
memory granule.

Add a new kmalloc_uaf_16() tests that relies on UAF, and a new
kasan_bitops_tags() test that is tailored to tag-based mode, as it's
hard to adopt the existing kmalloc_oob_16() and kasan_bitops_generic()
(renamed from kasan_bitops()) without losing the precision.

Add new kmalloc_uaf_16() and kasan_bitops_uaf() tests that rely on UAFs,
as it's hard to adopt the existing kmalloc_oob_16() and
kasan_bitops_oob() (rename from kasan_bitops()) without losing the
precision.

Disable kasan_global_oob() and kasan_alloca_oob_left/right() as SW_TAGS
mode doesn't instrument globals nor dynamic allocas.

Signed-off-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Tested-by: David Gow <davidgow@google.com>
Link: https://lkml.kernel.org/r/76eee17b6531ca8b3ca92b240cb2fd23204aaff7.1603129942.git.andreyknvl@google.com
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/lib/test_kasan.c b/lib/test_kasan.c
index 63c2617..662f862 100644 (file)
--- a/lib/test_kasan.c
+++ b/lib/test_kasan.c
@@ -216,6 +216,12 @@ static void kmalloc_oob_16(struct kunit *test)
                u64 words[2];
        } *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;
+       }
+
        ptr1 = kmalloc(sizeof(*ptr1) - 3, GFP_KERNEL);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);
 
@@ -227,6 +233,23 @@ static void kmalloc_oob_16(struct kunit *test)
        kfree(ptr2);
 }
 
+static void kmalloc_uaf_16(struct kunit *test)
+{
+       struct {
+               u64 words[2];
+       } *ptr1, *ptr2;
+
+       ptr1 = kmalloc(sizeof(*ptr1), GFP_KERNEL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr1);
+
+       ptr2 = kmalloc(sizeof(*ptr2), GFP_KERNEL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr2);
+       kfree(ptr2);
+
+       KUNIT_EXPECT_KASAN_FAIL(test, *ptr1 = *ptr2);
+       kfree(ptr1);
+}
+
 static void kmalloc_oob_memset_2(struct kunit *test)
 {
        char *ptr;
@@ -429,6 +452,12 @@ static void kasan_global_oob(struct kunit *test)
        volatile int i = 3;
        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;
+       }
+
        KUNIT_EXPECT_KASAN_FAIL(test, *(volatile char *)p);
 }
 
@@ -467,6 +496,12 @@ static void kasan_alloca_oob_left(struct kunit *test)
        char alloca_array[i];
        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;
@@ -481,6 +516,12 @@ static void kasan_alloca_oob_right(struct kunit *test)
        char alloca_array[i];
        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;
@@ -551,6 +592,9 @@ static void kasan_memchr(struct kunit *test)
                return;
        }
 
+       if (OOB_TAG_OFF)
+               size = round_up(size, OOB_TAG_OFF);
+
        ptr = kmalloc(size, GFP_KERNEL | __GFP_ZERO);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
 
@@ -573,6 +617,9 @@ static void kasan_memcmp(struct kunit *test)
                return;
        }
 
+       if (OOB_TAG_OFF)
+               size = round_up(size, OOB_TAG_OFF);
+
        ptr = kmalloc(size, GFP_KERNEL | __GFP_ZERO);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
        memset(arr, 0, sizeof(arr));
@@ -619,13 +666,50 @@ static void kasan_strings(struct kunit *test)
        KUNIT_EXPECT_KASAN_FAIL(test, kasan_int_result = strnlen(ptr, 1));
 }
 
-static void kasan_bitops(struct kunit *test)
+static void kasan_bitops_modify(struct kunit *test, int nr, void *addr)
+{
+       KUNIT_EXPECT_KASAN_FAIL(test, set_bit(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, __set_bit(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, clear_bit(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, __clear_bit(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, clear_bit_unlock(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, __clear_bit_unlock(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, change_bit(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, __change_bit(nr, addr));
+}
+
+static void kasan_bitops_test_and_modify(struct kunit *test, int nr, void *addr)
+{
+       KUNIT_EXPECT_KASAN_FAIL(test, test_and_set_bit(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, __test_and_set_bit(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, test_and_set_bit_lock(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, test_and_clear_bit(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, __test_and_clear_bit(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, test_and_change_bit(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, __test_and_change_bit(nr, addr));
+       KUNIT_EXPECT_KASAN_FAIL(test, kasan_int_result = test_bit(nr, addr));
+
+#if defined(clear_bit_unlock_is_negative_byte)
+       KUNIT_EXPECT_KASAN_FAIL(test, kasan_int_result =
+                               clear_bit_unlock_is_negative_byte(nr, addr));
+#endif
+}
+
+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;
+       }
+
        /*
         * Allocate 1 more byte, which causes kzalloc to round up to 16-bytes;
         * this way we do not actually corrupt other memory.
         */
-       long *bits = kzalloc(sizeof(*bits) + 1, GFP_KERNEL);
+       bits = kzalloc(sizeof(*bits) + 1, GFP_KERNEL);
        KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bits);
 
        /*
@@ -633,55 +717,34 @@ static void kasan_bitops(struct kunit *test)
         * below accesses are still out-of-bounds, since bitops are defined to
         * operate on the whole long the bit is in.
         */
-       KUNIT_EXPECT_KASAN_FAIL(test, set_bit(BITS_PER_LONG, bits));
-
-       KUNIT_EXPECT_KASAN_FAIL(test, __set_bit(BITS_PER_LONG, bits));
-
-       KUNIT_EXPECT_KASAN_FAIL(test, clear_bit(BITS_PER_LONG, bits));
-
-       KUNIT_EXPECT_KASAN_FAIL(test, __clear_bit(BITS_PER_LONG, bits));
-
-       KUNIT_EXPECT_KASAN_FAIL(test, clear_bit_unlock(BITS_PER_LONG, bits));
-
-       KUNIT_EXPECT_KASAN_FAIL(test, __clear_bit_unlock(BITS_PER_LONG, bits));
-
-       KUNIT_EXPECT_KASAN_FAIL(test, change_bit(BITS_PER_LONG, bits));
-
-       KUNIT_EXPECT_KASAN_FAIL(test, __change_bit(BITS_PER_LONG, bits));
+       kasan_bitops_modify(test, BITS_PER_LONG, bits);
 
        /*
         * Below calls try to access bit beyond allocated memory.
         */
-       KUNIT_EXPECT_KASAN_FAIL(test,
-               test_and_set_bit(BITS_PER_LONG + BITS_PER_BYTE, bits));
-
-       KUNIT_EXPECT_KASAN_FAIL(test,
-               __test_and_set_bit(BITS_PER_LONG + BITS_PER_BYTE, bits));
-
-       KUNIT_EXPECT_KASAN_FAIL(test,
-               test_and_set_bit_lock(BITS_PER_LONG + BITS_PER_BYTE, bits));
+       kasan_bitops_test_and_modify(test, BITS_PER_LONG + BITS_PER_BYTE, bits);
 
-       KUNIT_EXPECT_KASAN_FAIL(test,
-               test_and_clear_bit(BITS_PER_LONG + BITS_PER_BYTE, bits));
+       kfree(bits);
+}
 
-       KUNIT_EXPECT_KASAN_FAIL(test,
-               __test_and_clear_bit(BITS_PER_LONG + BITS_PER_BYTE, bits));
+static void kasan_bitops_tags(struct kunit *test)
+{
+       long *bits;
 
-       KUNIT_EXPECT_KASAN_FAIL(test,
-               test_and_change_bit(BITS_PER_LONG + BITS_PER_BYTE, 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;
+       }
 
-       KUNIT_EXPECT_KASAN_FAIL(test,
-               __test_and_change_bit(BITS_PER_LONG + BITS_PER_BYTE, bits));
+       /* Allocation size will be rounded to up granule size, which is 16. */
+       bits = kzalloc(sizeof(*bits), GFP_KERNEL);
+       KUNIT_ASSERT_NOT_ERR_OR_NULL(test, bits);
 
-       KUNIT_EXPECT_KASAN_FAIL(test,
-               kasan_int_result =
-                       test_bit(BITS_PER_LONG + BITS_PER_BYTE, 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]);
 
-#if defined(clear_bit_unlock_is_negative_byte)
-       KUNIT_EXPECT_KASAN_FAIL(test,
-               kasan_int_result = clear_bit_unlock_is_negative_byte(
-                       BITS_PER_LONG + BITS_PER_BYTE, bits));
-#endif
        kfree(bits);
 }
 
@@ -728,6 +791,7 @@ static struct kunit_case kasan_kunit_test_cases[] = {
        KUNIT_CASE(kmalloc_oob_krealloc_more),
        KUNIT_CASE(kmalloc_oob_krealloc_less),
        KUNIT_CASE(kmalloc_oob_16),
+       KUNIT_CASE(kmalloc_uaf_16),
        KUNIT_CASE(kmalloc_oob_in_memset),
        KUNIT_CASE(kmalloc_oob_memset_2),
        KUNIT_CASE(kmalloc_oob_memset_4),
@@ -751,7 +815,8 @@ static struct kunit_case kasan_kunit_test_cases[] = {
        KUNIT_CASE(kasan_memchr),
        KUNIT_CASE(kasan_memcmp),
        KUNIT_CASE(kasan_strings),
-       KUNIT_CASE(kasan_bitops),
+       KUNIT_CASE(kasan_bitops_generic),
+       KUNIT_CASE(kasan_bitops_tags),
        KUNIT_CASE(kmalloc_double_kzfree),
        KUNIT_CASE(vmalloc_oob),
        {}