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Date: Tue, 18 Oct 2022 11:54:28 -0700 From: Nathan Chancellor <nathan@...nel.org> To: Kees Cook <keescook@...omium.org> Cc: David Gow <davidgow@...gle.com>, "Tobin C . Harding" <tobin@...nel.org>, linux-kernel@...r.kernel.org, linux-hardening@...r.kernel.org Subject: Re: [PATCH] string: Convert strscpy() self-test to KUnit On Tue, Oct 18, 2022 at 01:28:59AM -0700, Kees Cook wrote: > Convert the strscpy() self-test to a KUnit test. > > Cc: David Gow <davidgow@...gle.com> > Cc: Tobin C. Harding <tobin@...nel.org> > Signed-off-by: Kees Cook <keescook@...omium.org> I ran the following commands and they all passed: $ tools/testing/kunit/kunit.py run --arch arm64 --cross_compile aarch64-linux-gnu- strscpy $ tools/testing/kunit/kunit.py run --arch arm64 --make_options LLVM=1 strscpy $ tools/testing/kunit/kunit.py run --arch x86_64 strscpy $ tools/testing/kunit/kunit.py run --arch x86_64 --make_options LLVM=1 strscpy Tested-by: Nathan Chancellor <nathan@...nel.org> > --- > 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@...nel.org>"); > +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@...nel.org>"); > -MODULE_LICENSE("GPL"); > -- > 2.34.1 >
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