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linux/fs/tests/exec_kunit.c
Kees Cook b6f5ee4d53 execve: Move KUnit tests to tests/ subdirectory 
Move the exec KUnit tests into a separate directory to avoid polluting
the local directory namespace. Additionally update MAINTAINERS for the
new files.

Reviewed-by: David Gow <davidgow@google.com>
Reviewed-by: SeongJae Park <sj@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Link: https://lore.kernel.org/r/20240720170310.it.942-kees@kernel.org
Signed-off-by: Kees Cook <kees@kernel.org>
2024-07-22 18:25:47 -07:00

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// SPDX-License-Identifier: GPL-2.0-only
#include <kunit/test.h>
struct bprm_stack_limits_result {
struct linux_binprm bprm;
int expected_rc;
unsigned long expected_argmin;
};
static const struct bprm_stack_limits_result bprm_stack_limits_results[] = {
/* Negative argc/envc counts produce -E2BIG */
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
.argc = INT_MIN, .envc = INT_MIN }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
.argc = 5, .envc = -1 }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
.argc = -1, .envc = 10 }, .expected_rc = -E2BIG },
/* The max value of argc or envc is MAX_ARG_STRINGS. */
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
.argc = INT_MAX, .envc = INT_MAX }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
.argc = MAX_ARG_STRINGS, .envc = MAX_ARG_STRINGS }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
.argc = 0, .envc = MAX_ARG_STRINGS }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
.argc = MAX_ARG_STRINGS, .envc = 0 }, .expected_rc = -E2BIG },
/*
* On 32-bit system these argc and envc counts, while likely impossible
* to represent within the associated TASK_SIZE, could overflow the
* limit calculation, and bypass the ptr_size <= limit check.
*/
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ULONG_MAX,
.argc = 0x20000001, .envc = 0x20000001 }, .expected_rc = -E2BIG },
#ifdef CONFIG_MMU
/* Make sure a pathological bprm->p doesn't cause an overflow. */
{ { .p = sizeof(void *), .rlim_stack.rlim_cur = ULONG_MAX,
.argc = 10, .envc = 10 }, .expected_rc = -E2BIG },
#endif
/*
* 0 rlim_stack will get raised to ARG_MAX. With 1 string pointer,
* we should see p - ARG_MAX + sizeof(void *).
*/
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
.argc = 1, .envc = 0 }, .expected_argmin = ULONG_MAX - ARG_MAX + sizeof(void *)},
/* Validate that argc is always raised to a minimum of 1. */
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
.argc = 0, .envc = 0 }, .expected_argmin = ULONG_MAX - ARG_MAX + sizeof(void *)},
/*
* 0 rlim_stack will get raised to ARG_MAX. With pointers filling ARG_MAX,
* we should see -E2BIG. (Note argc is always raised to at least 1.)
*/
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
.argc = ARG_MAX / sizeof(void *), .envc = 0 }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
.argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
.argc = ARG_MAX / sizeof(void *) + 1, .envc = 0 }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
.argc = 0, .envc = ARG_MAX / sizeof(void *) }, .expected_rc = -E2BIG },
/* And with one less, we see space for exactly 1 pointer. */
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
.argc = (ARG_MAX / sizeof(void *)) - 1, .envc = 0 },
.expected_argmin = ULONG_MAX - sizeof(void *) },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 0,
.argc = 0, .envc = (ARG_MAX / sizeof(void *)) - 2, },
.expected_argmin = ULONG_MAX - sizeof(void *) },
/* If we raise rlim_stack / 4 to exactly ARG_MAX, nothing changes. */
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
.argc = ARG_MAX / sizeof(void *), .envc = 0 }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
.argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
.argc = ARG_MAX / sizeof(void *) + 1, .envc = 0 }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
.argc = 0, .envc = ARG_MAX / sizeof(void *) }, .expected_rc = -E2BIG },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
.argc = (ARG_MAX / sizeof(void *)) - 1, .envc = 0 },
.expected_argmin = ULONG_MAX - sizeof(void *) },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = ARG_MAX * 4,
.argc = 0, .envc = (ARG_MAX / sizeof(void *)) - 2, },
.expected_argmin = ULONG_MAX - sizeof(void *) },
/* But raising it another pointer * 4 will provide space for 1 more pointer. */
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = (ARG_MAX + sizeof(void *)) * 4,
.argc = ARG_MAX / sizeof(void *), .envc = 0 },
.expected_argmin = ULONG_MAX - sizeof(void *) },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = (ARG_MAX + sizeof(void *)) * 4,
.argc = 0, .envc = ARG_MAX / sizeof(void *) - 1 },
.expected_argmin = ULONG_MAX - sizeof(void *) },
/* Raising rlim_stack / 4 to _STK_LIM / 4 * 3 will see more space. */
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3),
.argc = 0, .envc = 0 },
.expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3),
.argc = 0, .envc = 0 },
.expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
/* But raising it any further will see no increase. */
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * 3 + sizeof(void *)),
.argc = 0, .envc = 0 },
.expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * (_STK_LIM / 4 * + sizeof(void *)),
.argc = 0, .envc = 0 },
.expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * _STK_LIM,
.argc = 0, .envc = 0 },
.expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
{ { .p = ULONG_MAX, .rlim_stack.rlim_cur = 4 * _STK_LIM,
.argc = 0, .envc = 0 },
.expected_argmin = ULONG_MAX - (_STK_LIM / 4 * 3) + sizeof(void *) },
};
static void exec_test_bprm_stack_limits(struct kunit *test)
{
/* Double-check the constants. */
KUNIT_EXPECT_EQ(test, _STK_LIM, SZ_8M);
KUNIT_EXPECT_EQ(test, ARG_MAX, 32 * SZ_4K);
KUNIT_EXPECT_EQ(test, MAX_ARG_STRINGS, 0x7FFFFFFF);
for (int i = 0; i < ARRAY_SIZE(bprm_stack_limits_results); i++) {
const struct bprm_stack_limits_result *result = &bprm_stack_limits_results[i];
struct linux_binprm bprm = result->bprm;
int rc;
rc = bprm_stack_limits(&bprm);
KUNIT_EXPECT_EQ_MSG(test, rc, result->expected_rc, "on loop %d", i);
#ifdef CONFIG_MMU
KUNIT_EXPECT_EQ_MSG(test, bprm.argmin, result->expected_argmin, "on loop %d", i);
#endif
}
}
static struct kunit_case exec_test_cases[] = {
KUNIT_CASE(exec_test_bprm_stack_limits),
{},
};
static struct kunit_suite exec_test_suite = {
.name = "exec",
.test_cases = exec_test_cases,
};
kunit_test_suite(exec_test_suite);
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