Quelle  randstruct_kunit.c   Sprache: C

// 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 <kunit/test.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/string.h>

#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)
};

#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;
};

struct contains_func_untouched {
 struct randstruct_funcs_shuffled inner;
 DO_MANY_MEMBERS(func_member)
} __no_randomize_layout;

struct contains_func_shuffled {
 struct randstruct_funcs_shuffled inner;
 DO_MANY_MEMBERS(func_member)
};
#undef func_member

#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, checker...) \
 mismatches = 0;      \
 DO_MANY_MEMBERS(checker, 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");

static void randstruct_layout_same(struct kunit *test)
{
 int mismatches;

 check_pair(EXPECT_EQ, struct randstruct_untouched, struct randstruct_untouched,
     check_mismatch)
 check_pair(EXPECT_GT, struct randstruct_untouched, struct randstruct_shuffled,
     check_mismatch)
}

static void randstruct_layout_mixed(struct kunit *test)
{
 int mismatches;

 check_pair(EXPECT_EQ, struct randstruct_mixed_untouched, struct randstruct_mixed_untouched,
     check_mismatch)
 check_pair(EXPECT_GT, struct randstruct_mixed_untouched, struct randstruct_mixed_shuffled,
     check_mismatch)
}

static void randstruct_layout_fptr(struct kunit *test)
{
 int mismatches;

 check_pair(EXPECT_EQ, struct randstruct_untouched, struct randstruct_untouched,
     check_mismatch)
 check_pair(EXPECT_GT, struct randstruct_untouched, struct randstruct_funcs_shuffled,
     check_mismatch)
 check_pair(EXPECT_GT, struct randstruct_funcs_untouched, struct randstruct_funcs_shuffled,
     check_mismatch)
}

#define check_mismatch_prefixed(x, prefix, untouched, shuffled) \
 check_mismatch(prefix.x, untouched, shuffled)

static void randstruct_layout_fptr_deep(struct kunit *test)
{
 int mismatches;

 if (IS_ENABLED(CONFIG_CC_IS_CLANG))
  kunit_skip(test, "Clang randstruct misses inner functions: https://github.com/llvm/llvm-project/issues/138355");

 check_pair(EXPECT_EQ, struct contains_func_untouched, struct contains_func_untouched,
   check_mismatch_prefixed, inner)

 check_pair(EXPECT_GT, struct contains_func_untouched, struct contains_func_shuffled,
   check_mismatch_prefixed, inner)
}

#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_same),
 KUNIT_CASE(randstruct_layout_mixed),
 KUNIT_CASE(randstruct_layout_fptr),
 KUNIT_CASE(randstruct_layout_fptr_deep),
 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");