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Message-Id: <20220902204351.2521805-3-keescook@chromium.org> Date: Fri, 2 Sep 2022 13:43:50 -0700 From: Kees Cook <keescook@...omium.org> To: Nick Desaulniers <ndesaulniers@...gle.com> Cc: Kees Cook <keescook@...omium.org>, Nathan Chancellor <nathan@...nel.org>, Tom Rix <trix@...hat.com>, Andrew Morton <akpm@...ux-foundation.org>, Vlastimil Babka <vbabka@...e.cz>, "Steven Rostedt (Google)" <rostedt@...dmis.org>, David Gow <davidgow@...gle.com>, Yury Norov <yury.norov@...il.com>, Masami Hiramatsu <mhiramat@...nel.org>, Sander Vanheule <sander@...nheule.net>, linux-hardening@...r.kernel.org, llvm@...ts.linux.dev, Peter Zijlstra <peterz@...radead.org>, Josh Poimboeuf <jpoimboe@...nel.org>, Dan Williams <dan.j.williams@...el.com>, Isabella Basso <isabbasso@...eup.net>, Eric Dumazet <edumazet@...gle.com>, Rasmus Villemoes <linux@...musvillemoes.dk>, Eric Biggers <ebiggers@...gle.com>, Hannes Reinecke <hare@...e.de>, linux-kernel@...r.kernel.org Subject: [PATCH v2 2/3] fortify: Add KUnit test for FORTIFY_SOURCE internals Add lib/fortify_kunit.c KUnit test for checking the expected behavioral characteristics of FORTIFY_SOURCE internals. Cc: Nick Desaulniers <ndesaulniers@...gle.com> Cc: Nathan Chancellor <nathan@...nel.org> Cc: Tom Rix <trix@...hat.com> Cc: Andrew Morton <akpm@...ux-foundation.org> Cc: Vlastimil Babka <vbabka@...e.cz> Cc: "Steven Rostedt (Google)" <rostedt@...dmis.org> Cc: David Gow <davidgow@...gle.com> Cc: Yury Norov <yury.norov@...il.com> Cc: Masami Hiramatsu <mhiramat@...nel.org> Cc: Sander Vanheule <sander@...nheule.net> Cc: linux-hardening@...r.kernel.org Cc: llvm@...ts.linux.dev Signed-off-by: Kees Cook <keescook@...omium.org> --- MAINTAINERS | 1 + lib/Kconfig.debug | 9 ++++++ lib/Makefile | 1 + lib/fortify_kunit.c | 77 +++++++++++++++++++++++++++++++++++++++++++++ 4 files changed, 88 insertions(+) create mode 100644 lib/fortify_kunit.c diff --git a/MAINTAINERS b/MAINTAINERS index 9d7f64dc0efe..640115472199 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -8002,6 +8002,7 @@ L: linux-hardening@...r.kernel.org S: Supported T: git git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux.git for-next/hardening F: include/linux/fortify-string.h +F: lib/fortify_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 36455953d306..1f267c0ddffd 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2542,6 +2542,15 @@ config STACKINIT_KUNIT_TEST CONFIG_GCC_PLUGIN_STRUCTLEAK, CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF, or CONFIG_GCC_PLUGIN_STRUCTLEAK_BYREF_ALL. +config FORTIFY_KUNIT_TEST + tristate "Test fortified str*() and mem*() function internals at runtime" if !KUNIT_ALL_TESTS + depends on KUNIT && FORTIFY_SOURCE + default KUNIT_ALL_TESTS + help + Builds unit tests for checking internals of FORTIFY_SOURCE as used + by the str*() and mem*() family of functions. For testing runtime + traps of FORTIFY_SOURCE, see LKDTM's "FORTIFY_*" tests. + config TEST_UDELAY tristate "udelay test driver" help diff --git a/lib/Makefile b/lib/Makefile index f545140ed9e7..4ee1ceae945a 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -381,6 +381,7 @@ obj-$(CONFIG_IS_SIGNED_TYPE_KUNIT_TEST) += is_signed_type_kunit.o obj-$(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_GENERIC_LIB_DEVMEM_IS_ALLOWED) += devmem_is_allowed.o diff --git a/lib/fortify_kunit.c b/lib/fortify_kunit.c new file mode 100644 index 000000000000..4d7930b65107 --- /dev/null +++ b/lib/fortify_kunit.c @@ -0,0 +1,77 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Runtime test cases for CONFIG_FORTIFY_SOURCE that aren't expected to + * Oops th kernel on success. (For those, see drivers/misc/lkdtm/fortify.c) + * + * For corner cases with UBSAN, try testing with: + * + * ./tools/testing/kunit/kunit.py run --arch=x86_64 \ + * --kconfig_add CONFIG_FORTIFY_SOURCE=y \ + * --kconfig_add CONFIG_UBSAN=y \ + * --kconfig_add CONFIG_UBSAN_TRAP=y \ + * --kconfig_add CONFIG_UBSAN_BOUNDS=y \ + * --kconfig_add CONFIG_UBSAN_LOCAL_BOUNDS=y \ + * --make_options LLVM=1 fortify + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include <kunit/test.h> +#include <linux/string.h> +#include <linux/init.h> + +static const char array_of_10[] = "this is 10"; +static const char *ptr_of_11 = "this is 11!"; +static char array_unknown[] = "compiler thinks I might change"; + +static void known_sizes_test(struct kunit *test) +{ + KUNIT_EXPECT_EQ(test, __compiletime_strlen("88888888"), 8); + KUNIT_EXPECT_EQ(test, __compiletime_strlen(array_of_10), 10); + KUNIT_EXPECT_EQ(test, __compiletime_strlen(ptr_of_11), 11); + + KUNIT_EXPECT_EQ(test, __compiletime_strlen(array_unknown), SIZE_MAX); + /* Externally defined and dynamically sized string pointer: */ + KUNIT_EXPECT_EQ(test, __compiletime_strlen(saved_command_line), SIZE_MAX); +} + +/* This is volatile so the optimizer can't perform DCE below. */ +static volatile int pick; + +/* Not inline to keep optimizer from figuring out which string we want. */ +static noinline size_t want_minus_one(int pick) +{ + const char *str; + + switch (pick) { + case 1: + str = "4444"; + break; + case 2: + str = "333"; + break; + default: + str = "1"; + break; + } + return __compiletime_strlen(str); +} + +static void control_flow_split_test(struct kunit *test) +{ + KUNIT_EXPECT_EQ(test, want_minus_one(pick), SIZE_MAX); +} + +static struct kunit_case fortify_test_cases[] = { + KUNIT_CASE(known_sizes_test), + KUNIT_CASE(control_flow_split_test), + {} +}; + +static struct kunit_suite fortify_test_suite = { + .name = "fortify", + .test_cases = fortify_test_cases, +}; + +kunit_test_suite(fortify_test_suite); + +MODULE_LICENSE("GPL"); -- 2.34.1
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