[PATCH] string: Convert strscpy() self-test to KUnit

From: Kees Cook
Date: Tue Oct 18 2022 - 04:29:49 EST


Convert the strscpy() self-test to a KUnit test.

Cc: David Gow <davidgow@xxxxxxxxxx>
Cc: Tobin C. Harding <tobin@xxxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
---
MAINTAINERS | 1 +
lib/Kconfig.debug | 8 ++-
lib/Makefile | 2 +-
lib/strscpy_kunit.c | 129 +++++++++++++++++++++++++++++++++++++
lib/test_strscpy.c | 150 --------------------------------------------
5 files changed, 136 insertions(+), 154 deletions(-)
create mode 100644 lib/strscpy_kunit.c
delete mode 100644 lib/test_strscpy.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 9dd8d74c4df0..232d78340d79 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8045,6 +8045,7 @@ T: git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/har
F: include/linux/fortify-string.h
F: lib/fortify_kunit.c
F: lib/memcpy_kunit.c
+F: lib/strscpy_kunit.c
F: lib/test_fortify/*
F: scripts/test_fortify.sh
K: \b__NO_FORTIFY\b
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 3fc7abffc7aa..e0a4d52e434c 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -2215,9 +2215,6 @@ config STRING_SELFTEST
config TEST_STRING_HELPERS
tristate "Test functions located in the string_helpers module at runtime"

-config TEST_STRSCPY
- tristate "Test strscpy*() family of functions at runtime"
-
config TEST_KSTRTOX
tristate "Test kstrto*() family of functions at runtime"

@@ -2583,6 +2580,11 @@ config HW_BREAKPOINT_KUNIT_TEST

If unsure, say N.

+config STRSCPY_KUNIT_TEST
+ tristate "Test strscpy*() family of functions at runtime" if !KUNIT_ALL_TESTS
+ depends on KUNIT
+ default KUNIT_ALL_TESTS
+
config TEST_UDELAY
tristate "udelay test driver"
help
diff --git a/lib/Makefile b/lib/Makefile
index 161d6a724ff7..1905e5c26849 100644
--- a/lib/Makefile
+++ b/lib/Makefile
@@ -82,7 +82,6 @@ obj-$(CONFIG_TEST_DYNAMIC_DEBUG) += test_dynamic_debug.o
obj-$(CONFIG_TEST_PRINTF) += test_printf.o
obj-$(CONFIG_TEST_SCANF) += test_scanf.o
obj-$(CONFIG_TEST_BITMAP) += test_bitmap.o
-obj-$(CONFIG_TEST_STRSCPY) += test_strscpy.o
obj-$(CONFIG_TEST_UUID) += test_uuid.o
obj-$(CONFIG_TEST_XARRAY) += test_xarray.o
obj-$(CONFIG_TEST_PARMAN) += test_parman.o
@@ -380,6 +379,7 @@ obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += overflow_kunit.o
CFLAGS_stackinit_kunit.o += $(call cc-disable-warning, switch-unreachable)
obj-$(CONFIG_STACKINIT_KUNIT_TEST) += stackinit_kunit.o
obj-$(CONFIG_FORTIFY_KUNIT_TEST) += fortify_kunit.o
+obj-$(CONFIG_STRSCPY_KUNIT_TEST) += strscpy_kunit.o

obj-$(CONFIG_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o

diff --git a/lib/strscpy_kunit.c b/lib/strscpy_kunit.c
new file mode 100644
index 000000000000..98523f828d3a
--- /dev/null
+++ b/lib/strscpy_kunit.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Kernel module for testing 'strscpy' family of functions.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <kunit/test.h>
+#include <linux/string.h>
+
+/*
+ * tc() - Run a specific test case.
+ * @src: Source string, argument to strscpy_pad()
+ * @count: Size of destination buffer, argument to strscpy_pad()
+ * @expected: Expected return value from call to strscpy_pad()
+ * @terminator: 1 if there should be a terminating null byte 0 otherwise.
+ * @chars: Number of characters from the src string expected to be
+ * written to the dst buffer.
+ * @pad: Number of pad characters expected (in the tail of dst buffer).
+ * (@pad does not include the null terminator byte.)
+ *
+ * Calls strscpy_pad() and verifies the return value and state of the
+ * destination buffer after the call returns.
+ */
+static void tc(struct kunit *test, char *src, int count, int expected,
+ int chars, int terminator, int pad)
+{
+ int nr_bytes_poison;
+ int max_expected;
+ int max_count;
+ int written;
+ char buf[6];
+ int index, i;
+ const char POISON = 'z';
+
+ KUNIT_ASSERT_TRUE_MSG(test, src != NULL,
+ "null source string not supported");
+
+ memset(buf, POISON, sizeof(buf));
+ /* Future proofing test suite, validate args */
+ max_count = sizeof(buf) - 2; /* Space for null and to verify overflow */
+ max_expected = count - 1; /* Space for the null */
+
+ KUNIT_ASSERT_LE_MSG(test, count, max_count,
+ "count (%d) is too big (%d) ... aborting", count, max_count);
+ KUNIT_EXPECT_LE_MSG(test, expected, max_expected,
+ "expected (%d) is bigger than can possibly be returned (%d)",
+ expected, max_expected);
+
+ written = strscpy_pad(buf, src, count);
+ KUNIT_ASSERT_EQ(test, written, expected);
+
+ if (count && written == -E2BIG) {
+ KUNIT_ASSERT_EQ_MSG(test, 0, strncmp(buf, src, count - 1),
+ "buffer state invalid for -E2BIG");
+ KUNIT_ASSERT_EQ_MSG(test, buf[count - 1], '\0',
+ "too big string is not null terminated correctly");
+ }
+
+ for (i = 0; i < chars; i++)
+ KUNIT_ASSERT_EQ_MSG(test, buf[i], src[i],
+ "buf[i]==%c != src[i]==%c", buf[i], src[i]);
+
+ if (terminator)
+ KUNIT_ASSERT_EQ_MSG(test, buf[count - 1], '\0',
+ "string is not null terminated correctly");
+
+ for (i = 0; i < pad; i++) {
+ index = chars + terminator + i;
+ KUNIT_ASSERT_EQ_MSG(test, buf[index], '\0',
+ "padding missing at index: %d", i);
+ }
+
+ nr_bytes_poison = sizeof(buf) - chars - terminator - pad;
+ for (i = 0; i < nr_bytes_poison; i++) {
+ index = sizeof(buf) - 1 - i; /* Check from the end back */
+ KUNIT_ASSERT_EQ_MSG(test, buf[index], POISON,
+ "poison value missing at index: %d", i);
+ }
+}
+
+static void strscpy_test(struct kunit *test)
+{
+ /*
+ * tc() uses a destination buffer of size 6 and needs at
+ * least 2 characters spare (one for null and one to check for
+ * overflow). This means we should only call tc() with
+ * strings up to a maximum of 4 characters long and 'count'
+ * should not exceed 4. To test with longer strings increase
+ * the buffer size in tc().
+ */
+
+ /* tc(test, src, count, expected, chars, terminator, pad) */
+ tc(test, "a", 0, -E2BIG, 0, 0, 0);
+ tc(test, "", 0, -E2BIG, 0, 0, 0);
+
+ tc(test, "a", 1, -E2BIG, 0, 1, 0);
+ tc(test, "", 1, 0, 0, 1, 0);
+
+ tc(test, "ab", 2, -E2BIG, 1, 1, 0);
+ tc(test, "a", 2, 1, 1, 1, 0);
+ tc(test, "", 2, 0, 0, 1, 1);
+
+ tc(test, "abc", 3, -E2BIG, 2, 1, 0);
+ tc(test, "ab", 3, 2, 2, 1, 0);
+ tc(test, "a", 3, 1, 1, 1, 1);
+ tc(test, "", 3, 0, 0, 1, 2);
+
+ tc(test, "abcd", 4, -E2BIG, 3, 1, 0);
+ tc(test, "abc", 4, 3, 3, 1, 0);
+ tc(test, "ab", 4, 2, 2, 1, 1);
+ tc(test, "a", 4, 1, 1, 1, 2);
+ tc(test, "", 4, 0, 0, 1, 3);
+}
+
+static struct kunit_case strscpy_test_cases[] = {
+ KUNIT_CASE(strscpy_test),
+ {}
+};
+
+static struct kunit_suite strscpy_test_suite = {
+ .name = "strscpy",
+ .test_cases = strscpy_test_cases,
+};
+
+kunit_test_suite(strscpy_test_suite);
+
+MODULE_AUTHOR("Tobin C. Harding <tobin@xxxxxxxxxx>");
+MODULE_LICENSE("GPL");
diff --git a/lib/test_strscpy.c b/lib/test_strscpy.c
deleted file mode 100644
index a827f94601f5..000000000000
--- a/lib/test_strscpy.c
+++ /dev/null
@@ -1,150 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0+
-
-#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
-
-#include <linux/string.h>
-
-#include "../tools/testing/selftests/kselftest_module.h"
-
-/*
- * Kernel module for testing 'strscpy' family of functions.
- */
-
-KSTM_MODULE_GLOBALS();
-
-/*
- * tc() - Run a specific test case.
- * @src: Source string, argument to strscpy_pad()
- * @count: Size of destination buffer, argument to strscpy_pad()
- * @expected: Expected return value from call to strscpy_pad()
- * @terminator: 1 if there should be a terminating null byte 0 otherwise.
- * @chars: Number of characters from the src string expected to be
- * written to the dst buffer.
- * @pad: Number of pad characters expected (in the tail of dst buffer).
- * (@pad does not include the null terminator byte.)
- *
- * Calls strscpy_pad() and verifies the return value and state of the
- * destination buffer after the call returns.
- */
-static int __init tc(char *src, int count, int expected,
- int chars, int terminator, int pad)
-{
- int nr_bytes_poison;
- int max_expected;
- int max_count;
- int written;
- char buf[6];
- int index, i;
- const char POISON = 'z';
-
- total_tests++;
-
- if (!src) {
- pr_err("null source string not supported\n");
- return -1;
- }
-
- memset(buf, POISON, sizeof(buf));
- /* Future proofing test suite, validate args */
- max_count = sizeof(buf) - 2; /* Space for null and to verify overflow */
- max_expected = count - 1; /* Space for the null */
- if (count > max_count) {
- pr_err("count (%d) is too big (%d) ... aborting", count, max_count);
- return -1;
- }
- if (expected > max_expected) {
- pr_warn("expected (%d) is bigger than can possibly be returned (%d)",
- expected, max_expected);
- }
-
- written = strscpy_pad(buf, src, count);
- if ((written) != (expected)) {
- pr_err("%d != %d (written, expected)\n", written, expected);
- goto fail;
- }
-
- if (count && written == -E2BIG) {
- if (strncmp(buf, src, count - 1) != 0) {
- pr_err("buffer state invalid for -E2BIG\n");
- goto fail;
- }
- if (buf[count - 1] != '\0') {
- pr_err("too big string is not null terminated correctly\n");
- goto fail;
- }
- }
-
- for (i = 0; i < chars; i++) {
- if (buf[i] != src[i]) {
- pr_err("buf[i]==%c != src[i]==%c\n", buf[i], src[i]);
- goto fail;
- }
- }
-
- if (terminator) {
- if (buf[count - 1] != '\0') {
- pr_err("string is not null terminated correctly\n");
- goto fail;
- }
- }
-
- for (i = 0; i < pad; i++) {
- index = chars + terminator + i;
- if (buf[index] != '\0') {
- pr_err("padding missing at index: %d\n", i);
- goto fail;
- }
- }
-
- nr_bytes_poison = sizeof(buf) - chars - terminator - pad;
- for (i = 0; i < nr_bytes_poison; i++) {
- index = sizeof(buf) - 1 - i; /* Check from the end back */
- if (buf[index] != POISON) {
- pr_err("poison value missing at index: %d\n", i);
- goto fail;
- }
- }
-
- return 0;
-fail:
- failed_tests++;
- return -1;
-}
-
-static void __init selftest(void)
-{
- /*
- * tc() uses a destination buffer of size 6 and needs at
- * least 2 characters spare (one for null and one to check for
- * overflow). This means we should only call tc() with
- * strings up to a maximum of 4 characters long and 'count'
- * should not exceed 4. To test with longer strings increase
- * the buffer size in tc().
- */
-
- /* tc(src, count, expected, chars, terminator, pad) */
- KSTM_CHECK_ZERO(tc("a", 0, -E2BIG, 0, 0, 0));
- KSTM_CHECK_ZERO(tc("", 0, -E2BIG, 0, 0, 0));
-
- KSTM_CHECK_ZERO(tc("a", 1, -E2BIG, 0, 1, 0));
- KSTM_CHECK_ZERO(tc("", 1, 0, 0, 1, 0));
-
- KSTM_CHECK_ZERO(tc("ab", 2, -E2BIG, 1, 1, 0));
- KSTM_CHECK_ZERO(tc("a", 2, 1, 1, 1, 0));
- KSTM_CHECK_ZERO(tc("", 2, 0, 0, 1, 1));
-
- KSTM_CHECK_ZERO(tc("abc", 3, -E2BIG, 2, 1, 0));
- KSTM_CHECK_ZERO(tc("ab", 3, 2, 2, 1, 0));
- KSTM_CHECK_ZERO(tc("a", 3, 1, 1, 1, 1));
- KSTM_CHECK_ZERO(tc("", 3, 0, 0, 1, 2));
-
- KSTM_CHECK_ZERO(tc("abcd", 4, -E2BIG, 3, 1, 0));
- KSTM_CHECK_ZERO(tc("abc", 4, 3, 3, 1, 0));
- KSTM_CHECK_ZERO(tc("ab", 4, 2, 2, 1, 1));
- KSTM_CHECK_ZERO(tc("a", 4, 1, 1, 1, 2));
- KSTM_CHECK_ZERO(tc("", 4, 0, 0, 1, 3));
-}
-
-KSTM_MODULE_LOADERS(test_strscpy);
-MODULE_AUTHOR("Tobin C. Harding <tobin@xxxxxxxxxx>");
-MODULE_LICENSE("GPL");
--
2.34.1