fs/tests/exec_kunit.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 #include <kunit/test.h>
   3
   4 struct bprm_stack_limits_result {
   5         struct linux_binprm bprm;
   6         int expected_rc;
   7         unsigned long expected_argmin;
   8 };
   9
  10 static const struct bprm_stack_limits_result bprm_stack_limits_results[] = {
  11         /* Negative argc/envc counts produce -E2BIG */
  12         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
  13             .argc = INT_MIN, .envc = INT_MIN }, .expected_rc = -E2BIG },
  14         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
  15             .argc = 5, .envc = -1 }, .expected_rc = -E2BIG },
  16         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
  17             .argc = -1, .envc = 10 }, .expected_rc = -E2BIG },
  18         /* The max value of argc or envc is MAX_ARG_STRINGS. */
  19         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
  20             .argc = INT_MAX, .envc = INT_MAX }, .expected_rc = -E2BIG },
  21         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
  22             .argc = MAX_ARG_STRINGS, .envc = MAX_ARG_STRINGS }, .expected_rc = -E2BIG },
  23         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
  24             .argc = 0, .envc = MAX_ARG_STRINGS }, .expected_rc = -E2BIG },
  25         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
  26             .argc = MAX_ARG_STRINGS, .envc = 0 }, .expected_rc = -E2BIG },
  27         /*
  28          * On 32-bit system these argc and envc counts, while likely impossible
  29          * to represent within the associated TASK_SIZE, could overflow the
  30          * limit calculation, and bypass the ptr_size <= limit check.
  31          */
  32         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
  33             .argc = 0x20000001, .envc = 0x20000001 }, .expected_rc = -E2BIG },
  34 #ifdef CONFIG_MMU
  35         /* Make sure a pathological bprm->p doesn't cause an overflow. */
  36         { { .p = sizeof(void *), .rlim_stack.rlim_cur = ULONG_MAX,
  37             .argc = 10, .envc = 10 }, .expected_rc = -E2BIG },
  38 #endif
  39         /*
  40          * 0 rlim_stack will get raised to ARG_MAX. With 1 string pointer,
  41          * we should see p - ARG_MAX + sizeof(void *).
  42          */
  43         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
  44             .argc = 1, .envc = 0 }, .expected_argmin = ULONG_MAX - ARG_MAX + sizeof(void *)},
  45         /* Validate that argc is always raised to a minimum of 1. */
  46         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
  47             .argc = 0, .envc = 0 }, .expected_argmin = ULONG_MAX - ARG_MAX + sizeof(void *)},
  48         /*
  49          * 0 rlim_stack will get raised to ARG_MAX. With pointers filling ARG_MAX,
  50          * we should see -E2BIG. (Note argc is always raised to at least 1.)
  51          */
  52         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
  53             .argc = ARG_MAX / sizeof(void *), .envc = 0 }, .expected_rc = -E2BIG },
  54         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
  55             .argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 }, .expected_rc = -E2BIG },
  56         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
  57             .argc = ARG_MAX / sizeof(void *) + 1, .envc = 0 }, .expected_rc = -E2BIG },
  58         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
  59             .argc = 0, .envc = ARG_MAX / sizeof(void *) }, .expected_rc = -E2BIG },
  60         /* And with one less, we see space for exactly 1 pointer. */
  61         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
  62             .argc = (ARG_MAX / sizeof(void *)) - 1, .envc = 0 },
  63           .expected_argmin = ULONG_MAX - sizeof(void *) },
  64         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
  65             .argc = 0, .envc = (ARG_MAX / sizeof(void *)) - 2, },
  66           .expected_argmin = ULONG_MAX - sizeof(void *) },
  67         /* If we raise rlim_stack / 4 to exactly ARG_MAX, nothing changes. */
  68         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
  69             .argc = ARG_MAX / sizeof(void *), .envc = 0 }, .expected_rc = -E2BIG },
  70         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
  71             .argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 }, .expected_rc = -E2BIG },
  72         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
  73             .argc = ARG_MAX / sizeof(void *) + 1, .envc = 0 }, .expected_rc = -E2BIG },
  74         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
  75             .argc = 0, .envc = ARG_MAX / sizeof(void *) }, .expected_rc = -E2BIG },
  76         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
  77             .argc = (ARG_MAX / sizeof(void *)) - 1, .envc = 0 },
  78           .expected_argmin = ULONG_MAX - sizeof(void *) },
  79         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
  80             .argc = 0, .envc = (ARG_MAX / sizeof(void *)) - 2, },
  81           .expected_argmin = ULONG_MAX - sizeof(void *) },
  82         /* But raising it another pointer * 4 will provide space for 1 more pointer. */
  83         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = (ARG_MAX + sizeof(void *)) * 4,
  84             .argc = ARG_MAX / sizeof(void *), .envc = 0 },
  85           .expected_argmin = ULONG_MAX - sizeof(void *) },
  86         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = (ARG_MAX + sizeof(void *)) * 4,
  87             .argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 },
  88           .expected_argmin = ULONG_MAX - sizeof(void *) },
  89         /* Raising rlim_stack / 4 to _STK_LIM / 4 * 3 will see more space. */
  90         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3),
  91             .argc = 0, .envc = 0 },
  92           .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
  93         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3),
  94             .argc = 0, .envc = 0 },
  95           .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
  96         /* But raising it any further will see no increase. */
  97         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3 + sizeof(void *)),
  98             .argc = 0, .envc = 0 },
  99           .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
 100         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 *  + sizeof(void *)),
 101             .argc = 0, .envc = 0 },
 102           .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
 103         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * _STK_LIM,
 104             .argc = 0, .envc = 0 },
 105           .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
 106         { { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * _STK_LIM,
 107             .argc = 0, .envc = 0 },
 108           .expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
 109 };
 110
 111 static void exec_test_bprm_stack_limits(struct kunit *test)
 112 {
 113         /* Double-check the constants. */
 114         KUNIT_EXPECT_EQ(test, _STK_LIM, SZ_8M);
 115         KUNIT_EXPECT_EQ(test, ARG_MAX, 32 * SZ_4K);
 116         KUNIT_EXPECT_EQ(test, MAX_ARG_STRINGS, 0x7FFFFFFF);
 117
 118         for (int i = 0; i < ARRAY_SIZE(bprm_stack_limits_results); i++) {
 119                 const struct bprm_stack_limits_result *result = &bprm_stack_limits_results[i];
 120                 struct linux_binprm bprm = result->bprm;
 121                 int rc;
 122
 123                 rc = bprm_stack_limits(&bprm);
 124                 KUNIT_EXPECT_EQ_MSG(test, rc, result->expected_rc, "on loop %d", i);
 125 #ifdef CONFIG_MMU
 126                 KUNIT_EXPECT_EQ_MSG(test, bprm.argmin, result->expected_argmin, "on loop %d", i);
 127 #endif
 128         }
 129 }
 130
 131 static struct kunit_case exec_test_cases[] = {
 132         KUNIT_CASE(exec_test_bprm_stack_limits),
 133         {},
 134 };
 135
 136 static struct kunit_suite exec_test_suite = {
 137         .name = "exec",
 138         .test_cases = exec_test_cases,
 139 };
 140
 141 kunit_test_suite(exec_test_suite);