From: Kees Cook Date: Sun, 27 Apr 2025 00:21:01 +0000 (-0700) Subject: lib/tests: Add randstruct KUnit test X-Git-Tag: v6.16-rc1~85^2~6 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=b370f7eacdcfe1dd17bee00506296aa3fdc773cb;p=linux-2.6-block.git lib/tests: Add randstruct KUnit test Perform basic validation about layout randomization and initialization tracking when using CONFIG_RANDSTRUCT=y. Tested using: $ ./tools/testing/kunit/kunit.py run \ --kconfig_add CONFIG_RANDSTRUCT_FULL=y \ randstruct [17:22:30] ================= randstruct (2 subtests) ================== [17:22:30] [PASSED] randstruct_layout [17:22:30] [PASSED] randstruct_initializers [17:22:30] =================== [PASSED] randstruct ==================== [17:22:30] ============================================================ [17:22:30] Testing complete. Ran 2 tests: passed: 2 [17:22:30] Elapsed time: 5.091s total, 0.001s configuring, 4.974s building, 0.086s running Adding "--make_option LLVM=1" can be used to test Clang, which also passes. Acked-by: David Gow Signed-off-by: Kees Cook --- diff --git a/MAINTAINERS b/MAINTAINERS index 3cbf9ac0d83f..dc535c67a745 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -12892,6 +12892,7 @@ F: include/linux/overflow.h F: include/linux/randomize_kstack.h F: include/linux/ucopysize.h F: kernel/configs/hardening.config +F: lib/tests/randstruct_kunit.c F: lib/tests/usercopy_kunit.c F: mm/usercopy.c F: security/Kconfig.hardening diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index f9051ab610d5..6479cec900c7 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -2863,6 +2863,14 @@ config OVERFLOW_KUNIT_TEST If unsure, say N. +config RANDSTRUCT_KUNIT_TEST + tristate "Test randstruct structure layout randomization at runtime" if !KUNIT_ALL_TESTS + depends on KUNIT + default KUNIT_ALL_TESTS + help + Builds unit tests for the checking CONFIG_RANDSTRUCT=y, which + randomizes structure layouts. + config STACKINIT_KUNIT_TEST tristate "Test level of stack variable initialization" if !KUNIT_ALL_TESTS depends on KUNIT diff --git a/lib/tests/Makefile b/lib/tests/Makefile index 5a4794c1826e..56d645014482 100644 --- a/lib/tests/Makefile +++ b/lib/tests/Makefile @@ -35,6 +35,7 @@ obj-$(CONFIG_MEMCPY_KUNIT_TEST) += memcpy_kunit.o CFLAGS_overflow_kunit.o = $(call cc-disable-warning, tautological-constant-out-of-range-compare) obj-$(CONFIG_OVERFLOW_KUNIT_TEST) += overflow_kunit.o obj-$(CONFIG_PRINTF_KUNIT_TEST) += printf_kunit.o +obj-$(CONFIG_RANDSTRUCT_KUNIT_TEST) += randstruct_kunit.o obj-$(CONFIG_SCANF_KUNIT_TEST) += scanf_kunit.o obj-$(CONFIG_SIPHASH_KUNIT_TEST) += siphash_kunit.o obj-$(CONFIG_SLUB_KUNIT_TEST) += slub_kunit.o diff --git a/lib/tests/randstruct_kunit.c b/lib/tests/randstruct_kunit.c new file mode 100644 index 000000000000..c796c8fae263 --- /dev/null +++ b/lib/tests/randstruct_kunit.c @@ -0,0 +1,283 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * Test cases for struct randomization, i.e. CONFIG_RANDSTRUCT=y. + * + * For example, see: + * "Running tests with kunit_tool" at Documentation/dev-tools/kunit/start.rst + * ./tools/testing/kunit/kunit.py run randstruct [--raw_output] \ + * [--make_option LLVM=1] \ + * --kconfig_add CONFIG_RANDSTRUCT_FULL=y + * + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt + +#include +#include +#include +#include +#include + +#define DO_MANY_MEMBERS(macro, args...) \ + macro(a, args) \ + macro(b, args) \ + macro(c, args) \ + macro(d, args) \ + macro(e, args) \ + macro(f, args) \ + macro(g, args) \ + macro(h, args) + +#define do_enum(x, ignored) MEMBER_NAME_ ## x, +enum randstruct_member_names { + DO_MANY_MEMBERS(do_enum) + MEMBER_NAME_MAX, +}; +/* Make sure the macros are working: want 8 test members. */ +_Static_assert(MEMBER_NAME_MAX == 8, "Number of test members changed?!"); + +/* This is an unsigned long member to match the function pointer size */ +#define unsigned_long_member(x, ignored) unsigned long x; +struct randstruct_untouched { + DO_MANY_MEMBERS(unsigned_long_member) +}; + +/* Struct explicitly marked with __randomize_layout. */ +struct randstruct_shuffled { + DO_MANY_MEMBERS(unsigned_long_member) +} __randomize_layout; +#undef unsigned_long_member + +/* Struct implicitly randomized from being all func ptrs. */ +#define func_member(x, ignored) size_t (*x)(int); +struct randstruct_funcs_untouched { + DO_MANY_MEMBERS(func_member) +} __no_randomize_layout; + +struct randstruct_funcs_shuffled { + DO_MANY_MEMBERS(func_member) +}; +#undef func_member + +#define func_body(x, ignored) \ +static noinline size_t func_##x(int arg) \ +{ \ + return offsetof(struct randstruct_funcs_untouched, x); \ +} +DO_MANY_MEMBERS(func_body) + +/* Various mixed types. */ +#define mixed_members \ + bool a; \ + short b; \ + unsigned int c __aligned(16); \ + size_t d; \ + char e; \ + u64 f; \ + union { \ + struct randstruct_shuffled shuffled; \ + uintptr_t g; \ + }; \ + union { \ + void *ptr; \ + char h; \ + }; + +struct randstruct_mixed_untouched { + mixed_members +}; + +struct randstruct_mixed_shuffled { + mixed_members +} __randomize_layout; +#undef mixed_members + +struct contains_randstruct_untouched { + int before; + struct randstruct_untouched untouched; + int after; +}; + +struct contains_randstruct_shuffled { + int before; + struct randstruct_shuffled shuffled; + int after; +}; + +static void randstruct_layout(struct kunit *test) +{ + int mismatches; + +#define check_mismatch(x, untouched, shuffled) \ + if (offsetof(untouched, x) != offsetof(shuffled, x)) \ + mismatches++; \ + kunit_info(test, #shuffled "::" #x " @ %zu (vs %zu)\n", \ + offsetof(shuffled, x), \ + offsetof(untouched, x)); \ + +#define check_pair(outcome, untouched, shuffled) \ + mismatches = 0; \ + DO_MANY_MEMBERS(check_mismatch, untouched, shuffled) \ + kunit_info(test, "Differing " #untouched " vs " #shuffled " member positions: %d\n", \ + mismatches); \ + KUNIT_##outcome##_MSG(test, mismatches, 0, \ + #untouched " vs " #shuffled " layouts: unlucky or broken?\n"); + + check_pair(EXPECT_EQ, struct randstruct_untouched, struct randstruct_untouched) + check_pair(EXPECT_GT, struct randstruct_untouched, struct randstruct_shuffled) + check_pair(EXPECT_GT, struct randstruct_untouched, struct randstruct_funcs_shuffled) + check_pair(EXPECT_GT, struct randstruct_funcs_untouched, struct randstruct_funcs_shuffled) + check_pair(EXPECT_GT, struct randstruct_mixed_untouched, struct randstruct_mixed_shuffled) +#undef check_pair + +#undef check_mismatch +} + +#define check_mismatch(x, ignore) \ + KUNIT_EXPECT_EQ_MSG(test, untouched->x, shuffled->x, \ + "Mismatched member value in %s initializer\n", \ + name); + +static void test_check_init(struct kunit *test, const char *name, + struct randstruct_untouched *untouched, + struct randstruct_shuffled *shuffled) +{ + DO_MANY_MEMBERS(check_mismatch) +} + +static void test_check_mixed_init(struct kunit *test, const char *name, + struct randstruct_mixed_untouched *untouched, + struct randstruct_mixed_shuffled *shuffled) +{ + DO_MANY_MEMBERS(check_mismatch) +} +#undef check_mismatch + +#define check_mismatch(x, ignore) \ + KUNIT_EXPECT_EQ_MSG(test, untouched->untouched.x, \ + shuffled->shuffled.x, \ + "Mismatched member value in %s initializer\n", \ + name); +static void test_check_contained_init(struct kunit *test, const char *name, + struct contains_randstruct_untouched *untouched, + struct contains_randstruct_shuffled *shuffled) +{ + DO_MANY_MEMBERS(check_mismatch) +} +#undef check_mismatch + +#define check_mismatch(x, ignore) \ + KUNIT_EXPECT_PTR_EQ_MSG(test, untouched->x, shuffled->x, \ + "Mismatched member value in %s initializer\n", \ + name); + +static void test_check_funcs_init(struct kunit *test, const char *name, + struct randstruct_funcs_untouched *untouched, + struct randstruct_funcs_shuffled *shuffled) +{ + DO_MANY_MEMBERS(check_mismatch) +} +#undef check_mismatch + +static void randstruct_initializers(struct kunit *test) +{ +#define init_members \ + .a = 1, \ + .b = 3, \ + .c = 5, \ + .d = 7, \ + .e = 11, \ + .f = 13, \ + .g = 17, \ + .h = 19, + struct randstruct_untouched untouched = { + init_members + }; + struct randstruct_shuffled shuffled = { + init_members + }; + struct randstruct_mixed_untouched mixed_untouched = { + init_members + }; + struct randstruct_mixed_shuffled mixed_shuffled = { + init_members + }; + struct contains_randstruct_untouched contains_untouched = { + .untouched = { + init_members + }, + }; + struct contains_randstruct_shuffled contains_shuffled = { + .shuffled = { + init_members + }, + }; +#define func_member(x, ignored) \ + .x = func_##x, + struct randstruct_funcs_untouched funcs_untouched = { + DO_MANY_MEMBERS(func_member) + }; + struct randstruct_funcs_shuffled funcs_shuffled = { + DO_MANY_MEMBERS(func_member) + }; + + test_check_init(test, "named", &untouched, &shuffled); + test_check_init(test, "unnamed", &untouched, + &(struct randstruct_shuffled){ + init_members + }); + + test_check_contained_init(test, "named", &contains_untouched, &contains_shuffled); + test_check_contained_init(test, "unnamed", &contains_untouched, + &(struct contains_randstruct_shuffled){ + .shuffled = (struct randstruct_shuffled){ + init_members + }, + }); + + test_check_contained_init(test, "named", &contains_untouched, &contains_shuffled); + test_check_contained_init(test, "unnamed copy", &contains_untouched, + &(struct contains_randstruct_shuffled){ + /* full struct copy initializer */ + .shuffled = shuffled, + }); + + test_check_mixed_init(test, "named", &mixed_untouched, &mixed_shuffled); + test_check_mixed_init(test, "unnamed", &mixed_untouched, + &(struct randstruct_mixed_shuffled){ + init_members + }); + + test_check_funcs_init(test, "named", &funcs_untouched, &funcs_shuffled); + test_check_funcs_init(test, "unnamed", &funcs_untouched, + &(struct randstruct_funcs_shuffled){ + DO_MANY_MEMBERS(func_member) + }); + +#undef func_member +#undef init_members +} + +static int randstruct_test_init(struct kunit *test) +{ + if (!IS_ENABLED(CONFIG_RANDSTRUCT)) + kunit_skip(test, "Not built with CONFIG_RANDSTRUCT=y"); + + return 0; +} + +static struct kunit_case randstruct_test_cases[] = { + KUNIT_CASE(randstruct_layout), + KUNIT_CASE(randstruct_initializers), + {} +}; + +static struct kunit_suite randstruct_test_suite = { + .name = "randstruct", + .init = randstruct_test_init, + .test_cases = randstruct_test_cases, +}; + +kunit_test_suites(&randstruct_test_suite); + +MODULE_DESCRIPTION("Test cases for struct randomization"); +MODULE_LICENSE("GPL");