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| 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); |
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