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authorKees Cook <keescook@chromium.org>2022-10-02 09:51:46 -0700
committerKees Cook <keescook@chromium.org>2022-11-01 10:04:52 -0700
commit41eefc46a3a4682976afb5f8c4b9734ed6bfd406 (patch)
tree2c0976342fe9a23a9498aec8895b126a08f3168a /lib/strscpy_kunit.c
parent9e4a617757273a86b560c1ece40c48e4940a3c79 (diff)
string: Convert strscpy() self-test to KUnit
Convert the strscpy() self-test to a KUnit test. Cc: David Gow <davidgow@google.com> Cc: Tobin C. Harding <tobin@kernel.org> Tested-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/lkml/Y072ZMk/hNkfwqMv@dev-arch.thelio-3990X Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'lib/strscpy_kunit.c')
-rw-r--r--lib/strscpy_kunit.c129
1 files changed, 129 insertions, 0 deletions
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@kernel.org>");
+MODULE_LICENSE("GPL");