linux-kernel - [PATCH] mm: instrument copy_from/to_kernel

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Message-Id: <20240927151438.2143936-1-snovitoll@gmail.com>
Date: Fri, 27 Sep 2024 20:14:38 +0500
From: Sabyrzhan Tasbolatov <snovitoll@...il.com>
To: ryabinin.a.a@...il.com,
	glider@...gle.com,
	andreyknvl@...il.com,
	dvyukov@...gle.com,
	vincenzo.frascino@....com,
	akpm@...ux-foundation.org
Cc: kasan-dev@...glegroups.com,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	snovitoll@...il.com
Subject: [PATCH] mm: instrument copy_from/to_kernel_nofault

Instrument copy_from_kernel_nofault(), copy_to_kernel_nofault()
with instrument_memcpy_before() for KASAN, KCSAN checks and
instrument_memcpy_after() for KMSAN.

Tested on x86_64 and arm64 with CONFIG_KASAN_SW_TAGS.
On arm64 with CONFIG_KASAN_HW_TAGS, kunit test currently fails.
Need more clarification on it - currently, disabled in kunit test.

Reported-by: Andrey Konovalov <andreyknvl@...il.com>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=210505
Signed-off-by: Sabyrzhan Tasbolatov <snovitoll@...il.com>
---
 mm/kasan/kasan_test.c | 31 +++++++++++++++++++++++++++++++
 mm/maccess.c          |  8 ++++++--
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/mm/kasan/kasan_test.c b/mm/kasan/kasan_test.c
index 567d33b49..329d81518 100644
--- a/mm/kasan/kasan_test.c
+++ b/mm/kasan/kasan_test.c
@@ -1944,6 +1944,36 @@ static void match_all_mem_tag(struct kunit *test)
 	kfree(ptr);
 }
 
+static void copy_from_to_kernel_nofault_oob(struct kunit *test)
+{
+	char *ptr;
+	char buf[128];
+	size_t size = sizeof(buf);
+
+	/* Not detecting fails currently with HW_TAGS */
+	KASAN_TEST_NEEDS_CONFIG_OFF(test, CONFIG_KASAN_HW_TAGS);
+
+	ptr = kmalloc(size - KASAN_GRANULE_SIZE, GFP_KERNEL);
+	KUNIT_ASSERT_NOT_ERR_OR_NULL(test, ptr);
+	OPTIMIZER_HIDE_VAR(ptr);
+
+	if (IS_ENABLED(CONFIG_KASAN_SW_TAGS)) {
+		/* Check that the returned pointer is tagged. */
+		KUNIT_EXPECT_GE(test, (u8)get_tag(ptr), (u8)KASAN_TAG_MIN);
+		KUNIT_EXPECT_LT(test, (u8)get_tag(ptr), (u8)KASAN_TAG_KERNEL);
+	}
+
+	KUNIT_EXPECT_KASAN_FAIL(test,
+		copy_from_kernel_nofault(&buf[0], ptr, size));
+	KUNIT_EXPECT_KASAN_FAIL(test,
+		copy_from_kernel_nofault(ptr, &buf[0], size));
+	KUNIT_EXPECT_KASAN_FAIL(test,
+		copy_to_kernel_nofault(&buf[0], ptr, size));
+	KUNIT_EXPECT_KASAN_FAIL(test,
+		copy_to_kernel_nofault(ptr, &buf[0], size));
+	kfree(ptr);
+}
+
 static struct kunit_case kasan_kunit_test_cases[] = {
 	KUNIT_CASE(kmalloc_oob_right),
 	KUNIT_CASE(kmalloc_oob_left),
@@ -2017,6 +2047,7 @@ static struct kunit_case kasan_kunit_test_cases[] = {
 	KUNIT_CASE(match_all_not_assigned),
 	KUNIT_CASE(match_all_ptr_tag),
 	KUNIT_CASE(match_all_mem_tag),
+	KUNIT_CASE(copy_from_to_kernel_nofault_oob),
 	{}
 };
 
diff --git a/mm/maccess.c b/mm/maccess.c
index 518a25667..2c4251df4 100644
--- a/mm/maccess.c
+++ b/mm/maccess.c
@@ -15,7 +15,7 @@ bool __weak copy_from_kernel_nofault_allowed(const void *unsafe_src,
 
 #define copy_from_kernel_nofault_loop(dst, src, len, type, err_label)	\
 	while (len >= sizeof(type)) {					\
-		__get_kernel_nofault(dst, src, type, err_label);		\
+		__get_kernel_nofault(dst, src, type, err_label);	\
 		dst += sizeof(type);					\
 		src += sizeof(type);					\
 		len -= sizeof(type);					\
@@ -32,6 +32,7 @@ long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
 		return -ERANGE;
 
 	pagefault_disable();
+	instrument_memcpy_before(dst, src, size);
 	if (!(align & 7))
 		copy_from_kernel_nofault_loop(dst, src, size, u64, Efault);
 	if (!(align & 3))
@@ -39,6 +40,7 @@ long copy_from_kernel_nofault(void *dst, const void *src, size_t size)
 	if (!(align & 1))
 		copy_from_kernel_nofault_loop(dst, src, size, u16, Efault);
 	copy_from_kernel_nofault_loop(dst, src, size, u8, Efault);
+	instrument_memcpy_after(dst, src, size, 0);
 	pagefault_enable();
 	return 0;
 Efault:
@@ -49,7 +51,7 @@ EXPORT_SYMBOL_GPL(copy_from_kernel_nofault);
 
 #define copy_to_kernel_nofault_loop(dst, src, len, type, err_label)	\
 	while (len >= sizeof(type)) {					\
-		__put_kernel_nofault(dst, src, type, err_label);		\
+		__put_kernel_nofault(dst, src, type, err_label);	\
 		dst += sizeof(type);					\
 		src += sizeof(type);					\
 		len -= sizeof(type);					\
@@ -63,6 +65,7 @@ long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
 		align = (unsigned long)dst | (unsigned long)src;
 
 	pagefault_disable();
+	instrument_memcpy_before(dst, src, size);
 	if (!(align & 7))
 		copy_to_kernel_nofault_loop(dst, src, size, u64, Efault);
 	if (!(align & 3))
@@ -70,6 +73,7 @@ long copy_to_kernel_nofault(void *dst, const void *src, size_t size)
 	if (!(align & 1))
 		copy_to_kernel_nofault_loop(dst, src, size, u16, Efault);
 	copy_to_kernel_nofault_loop(dst, src, size, u8, Efault);
+	instrument_memcpy_after(dst, src, size, 0);
 	pagefault_enable();
 	return 0;
 Efault:
-- 
2.34.1