* [PATCH v1 2/2] selftests/harness: Merge TEST_F_FORK() into TEST_F()
2024-03-05 15:56 ` [PATCH v1 0/2] Merge TEST_F_FORK() into TEST_F() Mickaël Salaün
2024-03-05 15:56 ` [PATCH v1 1/2] selftests/landlock: Redefine TEST_F() as TEST_F_FORK() Mickaël Salaün
@ 2024-03-05 15:56 ` Mickaël Salaün
1 sibling, 0 replies; 3+ messages in thread
From: Mickaël Salaün @ 2024-03-05 15:56 UTC (permalink / raw)
To: Jakub Kicinski, Kees Cook, Mark Brown, Shuah Khan, davem
Cc: Mickaël Salaün, Günther Noack, Will Drewry,
edumazet, jakub, pabeni, linux-kernel, linux-kselftest,
linux-security-module, netdev
Replace Landlock-specific TEST_F_FORK() with an improved TEST_F() which
brings four related changes:
Run TEST_F()'s tests in a grandchild process to make it possible to
drop privileges and delegate teardown to the parent.
Compared to TEST_F_FORK(), simplify handling of the test grandchild
process thanks to vfork(2), and makes it generic (e.g. no explicit
conversion between exit code and _metadata).
Compared to TEST_F_FORK(), run teardown even when tests failed with an
assert thanks to commit 63e6b2a42342 ("selftests/harness: Run TEARDOWN
for ASSERT failures").
By default teardown is run by the grandchild process, but it can be run
by its parent process if _metadata->teardown_parent is set to true.
Update Landlock tests' fixture setup to set _metadata->teardown, and
remove now-invalid umount calls in Landlock test teardowns.
Simplify the test harness code by removing the no_print and step fields
which are not used. I added this feature just after I made
kselftest_harness.h more broadly available but this step counter
remained even though it wasn't needed after all. See commit 369130b63178
("selftests: Enhance kselftest_harness.h to print which assert failed").
Replace spaces with tabs in one line of __TEST_F_IMPL().
Cc: Günther Noack <gnoack@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Will Drewry <wad@chromium.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Mickaël Salaün <mic@digikod.net>
---
v5:
- Fix TEST_SIGNAL() by forwarding grandchild signal to parent.
- By default, run teardown in the grandchild, but allow teardown to be
run in its parent if _metadata->teardown_parent is set to true. This
fixes seccomp tests that have assumptions about the process
hierarchy.
- Remove now-invalid umount calls in Landlock test teardowns.
v4:
- GAND -> GRAND
- init child to 1, otherwise assert in setup triggers a longjmp
which in turn reads child without it ever getting initialized
(or being 0, i.e. we mistakenly assume we're in the grandchild)
---
tools/testing/selftests/kselftest_harness.h | 72 ++++++++++-----------
tools/testing/selftests/landlock/common.h | 62 +-----------------
tools/testing/selftests/landlock/fs_test.c | 22 +++----
3 files changed, 48 insertions(+), 108 deletions(-)
diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
index e05ac8261046..4f192904dfd6 100644
--- a/tools/testing/selftests/kselftest_harness.h
+++ b/tools/testing/selftests/kselftest_harness.h
@@ -95,14 +95,6 @@
* E.g., #define TH_LOG_ENABLED 1
*
* If no definition is provided, logging is enabled by default.
- *
- * If there is no way to print an error message for the process running the
- * test (e.g. not allowed to write to stderr), it is still possible to get the
- * ASSERT_* number for which the test failed. This behavior can be enabled by
- * writing `_metadata->no_print = true;` before the check sequence that is
- * unable to print. When an error occur, instead of printing an error message
- * and calling `abort(3)`, the test process call `_exit(2)` with the assert
- * number as argument, which is then printed by the parent process.
*/
#define TH_LOG(fmt, ...) do { \
if (TH_LOG_ENABLED) \
@@ -363,6 +355,11 @@
* Defines a test that depends on a fixture (e.g., is part of a test case).
* Very similar to TEST() except that *self* is the setup instance of fixture's
* datatype exposed for use by the implementation.
+ *
+ * The @test_name code is run in a separate process sharing the same memory
+ * (i.e. vfork), which means that the test process can update its privileges
+ * without impacting the related FIXTURE_TEARDOWN() (e.g. to remove files from
+ * a directory where write access was dropped).
*/
#define TEST_F(fixture_name, test_name) \
__TEST_F_IMPL(fixture_name, test_name, -1, TEST_TIMEOUT_DEFAULT)
@@ -384,17 +381,34 @@
{ \
/* fixture data is alloced, setup, and torn down per call. */ \
FIXTURE_DATA(fixture_name) self; \
+ pid_t child = 1; \
+ int status = 0; \
memset(&self, 0, sizeof(FIXTURE_DATA(fixture_name))); \
if (setjmp(_metadata->env) == 0) { \
- fixture_name##_setup(_metadata, &self, variant->data); \
- /* Let setup failure terminate early. */ \
- if (!_metadata->passed || _metadata->skip) \
- return; \
- _metadata->setup_completed = true; \
- fixture_name##_##test_name(_metadata, &self, variant->data); \
+ /* Use the same _metadata. */ \
+ child = vfork(); \
+ if (child == 0) { \
+ fixture_name##_setup(_metadata, &self, variant->data); \
+ /* Let setup failure terminate early. */ \
+ if (!_metadata->passed || _metadata->skip) \
+ _exit(0); \
+ _metadata->setup_completed = true; \
+ fixture_name##_##test_name(_metadata, &self, variant->data); \
+ } else if (child < 0 || child != waitpid(child, &status, 0)) { \
+ ksft_print_msg("ERROR SPAWNING TEST GRANDCHILD\n"); \
+ _metadata->passed = 0; \
+ } \
} \
- if (_metadata->setup_completed) \
+ if (child == 0) { \
+ if (_metadata->setup_completed && !_metadata->teardown_parent) \
+ fixture_name##_teardown(_metadata, &self, variant->data); \
+ _exit(0); \
+ } \
+ if (_metadata->setup_completed && _metadata->teardown_parent) \
fixture_name##_teardown(_metadata, &self, variant->data); \
+ if (!WIFEXITED(status) && WIFSIGNALED(status)) \
+ /* Forward signal to __wait_for_test(). */ \
+ kill(getpid(), WTERMSIG(status)); \
__test_check_assert(_metadata); \
} \
static struct __test_metadata \
@@ -404,6 +418,7 @@
.fixture = &_##fixture_name##_fixture_object, \
.termsig = signal, \
.timeout = tmout, \
+ .teardown_parent = false, \
}; \
static void __attribute__((constructor)) \
_register_##fixture_name##_##test_name(void) \
@@ -694,18 +709,12 @@
for (; _metadata->trigger; _metadata->trigger = \
__bail(_assert, _metadata))
-#define __INC_STEP(_metadata) \
- /* Keep "step" below 255 (which is used for "SKIP" reporting). */ \
- if (_metadata->passed && _metadata->step < 253) \
- _metadata->step++;
-
#define is_signed_type(var) (!!(((__typeof__(var))(-1)) < (__typeof__(var))1))
#define __EXPECT(_expected, _expected_str, _seen, _seen_str, _t, _assert) do { \
/* Avoid multiple evaluation of the cases */ \
__typeof__(_expected) __exp = (_expected); \
__typeof__(_seen) __seen = (_seen); \
- if (_assert) __INC_STEP(_metadata); \
if (!(__exp _t __seen)) { \
/* Report with actual signedness to avoid weird output. */ \
switch (is_signed_type(__exp) * 2 + is_signed_type(__seen)) { \
@@ -751,7 +760,6 @@
#define __EXPECT_STR(_expected, _seen, _t, _assert) do { \
const char *__exp = (_expected); \
const char *__seen = (_seen); \
- if (_assert) __INC_STEP(_metadata); \
if (!(strcmp(__exp, __seen) _t 0)) { \
__TH_LOG("Expected '%s' %s '%s'.", __exp, #_t, __seen); \
_metadata->passed = 0; \
@@ -837,10 +845,9 @@ struct __test_metadata {
int trigger; /* extra handler after the evaluation */
int timeout; /* seconds to wait for test timeout */
bool timed_out; /* did this test timeout instead of exiting? */
- __u8 step;
- bool no_print; /* manual trigger when TH_LOG_STREAM is not available */
bool aborted; /* stopped test due to failed ASSERT */
bool setup_completed; /* did setup finish? */
+ bool teardown_parent; /* run teardown in a parent process */
jmp_buf env; /* for exiting out of test early */
struct __test_results *results;
struct __test_metadata *prev, *next;
@@ -873,11 +880,8 @@ static inline int __bail(int for_realz, struct __test_metadata *t)
static inline void __test_check_assert(struct __test_metadata *t)
{
- if (t->aborted) {
- if (t->no_print)
- _exit(t->step);
+ if (t->aborted)
abort();
- }
}
struct __test_metadata *__active_test;
@@ -954,13 +958,12 @@ void __wait_for_test(struct __test_metadata *t)
case 0:
t->passed = 1;
break;
- /* Other failure, assume step report. */
+ /* Failure */
default:
t->passed = 0;
fprintf(TH_LOG_STREAM,
- "# %s: Test failed at step #%d\n",
- t->name,
- WEXITSTATUS(status));
+ "# %s: Test failed\n",
+ t->name);
}
}
} else if (WIFSIGNALED(status)) {
@@ -1114,8 +1117,6 @@ void __run_test(struct __fixture_metadata *f,
t->passed = 1;
t->skip = 0;
t->trigger = 0;
- t->step = 1;
- t->no_print = 0;
memset(t->results->reason, 0, sizeof(t->results->reason));
ksft_print_msg(" RUN %s%s%s.%s ...\n",
@@ -1137,8 +1138,7 @@ void __run_test(struct __fixture_metadata *f,
/* Pass is exit 0 */
if (t->passed)
_exit(0);
- /* Something else happened, report the step. */
- _exit(t->step);
+ _exit(1);
} else {
__wait_for_test(t);
}
diff --git a/tools/testing/selftests/landlock/common.h b/tools/testing/selftests/landlock/common.h
index f40146d40763..401e2eb092a3 100644
--- a/tools/testing/selftests/landlock/common.h
+++ b/tools/testing/selftests/landlock/common.h
@@ -23,66 +23,8 @@
#define __maybe_unused __attribute__((__unused__))
#endif
-/*
- * TEST_F_FORK() is useful when a test drop privileges but the corresponding
- * FIXTURE_TEARDOWN() requires them (e.g. to remove files from a directory
- * where write actions are denied). For convenience, FIXTURE_TEARDOWN() is
- * also called when the test failed, but not when FIXTURE_SETUP() failed. For
- * this to be possible, we must not call abort() but instead exit smoothly
- * (hence the step print).
- */
-/* clang-format off */
-#define TEST_F_FORK(fixture_name, test_name) \
- static void fixture_name##_##test_name##_child( \
- struct __test_metadata *_metadata, \
- FIXTURE_DATA(fixture_name) *self, \
- const FIXTURE_VARIANT(fixture_name) *variant); \
- __TEST_F_IMPL(fixture_name, test_name, -1, TEST_TIMEOUT_DEFAULT) \
- { \
- int status; \
- const pid_t child = fork(); \
- if (child < 0) \
- abort(); \
- if (child == 0) { \
- _metadata->no_print = 1; \
- fixture_name##_##test_name##_child(_metadata, self, variant); \
- if (_metadata->skip) \
- _exit(255); \
- if (_metadata->passed) \
- _exit(0); \
- _exit(_metadata->step); \
- } \
- if (child != waitpid(child, &status, 0)) \
- abort(); \
- if (WIFSIGNALED(status) || !WIFEXITED(status)) { \
- _metadata->passed = 0; \
- _metadata->step = 1; \
- return; \
- } \
- switch (WEXITSTATUS(status)) { \
- case 0: \
- _metadata->passed = 1; \
- break; \
- case 255: \
- _metadata->passed = 1; \
- _metadata->skip = 1; \
- break; \
- default: \
- _metadata->passed = 0; \
- _metadata->step = WEXITSTATUS(status); \
- break; \
- } \
- } \
- static void fixture_name##_##test_name##_child( \
- struct __test_metadata __attribute__((unused)) *_metadata, \
- FIXTURE_DATA(fixture_name) __attribute__((unused)) *self, \
- const FIXTURE_VARIANT(fixture_name) \
- __attribute__((unused)) *variant)
-/* clang-format on */
-
-/* Makes backporting easier. */
-#undef TEST_F
-#define TEST_F(fixture_name, test_name) TEST_F_FORK(fixture_name, test_name)
+/* TEST_F_FORK() should not be used for new tests. */
+#define TEST_F_FORK(fixture_name, test_name) TEST_F(fixture_name, test_name)
#ifndef landlock_create_ruleset
static inline int
diff --git a/tools/testing/selftests/landlock/fs_test.c b/tools/testing/selftests/landlock/fs_test.c
index 2d6d9b43d958..1d5952897e05 100644
--- a/tools/testing/selftests/landlock/fs_test.c
+++ b/tools/testing/selftests/landlock/fs_test.c
@@ -285,6 +285,8 @@ static void prepare_layout_opt(struct __test_metadata *const _metadata,
static void prepare_layout(struct __test_metadata *const _metadata)
{
+ _metadata->teardown_parent = true;
+
prepare_layout_opt(_metadata, &mnt_tmp);
}
@@ -3861,9 +3863,7 @@ FIXTURE_SETUP(layout1_bind)
FIXTURE_TEARDOWN(layout1_bind)
{
- set_cap(_metadata, CAP_SYS_ADMIN);
- EXPECT_EQ(0, umount(dir_s2d2));
- clear_cap(_metadata, CAP_SYS_ADMIN);
+ /* umount(dir_s2d2)) is handled by namespace lifetime. */
remove_layout1(_metadata);
@@ -4276,9 +4276,8 @@ FIXTURE_TEARDOWN(layout2_overlay)
EXPECT_EQ(0, remove_path(lower_fl1));
EXPECT_EQ(0, remove_path(lower_do1_fo2));
EXPECT_EQ(0, remove_path(lower_fo1));
- set_cap(_metadata, CAP_SYS_ADMIN);
- EXPECT_EQ(0, umount(LOWER_BASE));
- clear_cap(_metadata, CAP_SYS_ADMIN);
+
+ /* umount(LOWER_BASE)) is handled by namespace lifetime. */
EXPECT_EQ(0, remove_path(LOWER_BASE));
EXPECT_EQ(0, remove_path(upper_do1_fu3));
@@ -4287,14 +4286,11 @@ FIXTURE_TEARDOWN(layout2_overlay)
EXPECT_EQ(0, remove_path(upper_do1_fo2));
EXPECT_EQ(0, remove_path(upper_fo1));
EXPECT_EQ(0, remove_path(UPPER_WORK "/work"));
- set_cap(_metadata, CAP_SYS_ADMIN);
- EXPECT_EQ(0, umount(UPPER_BASE));
- clear_cap(_metadata, CAP_SYS_ADMIN);
+
+ /* umount(UPPER_BASE)) is handled by namespace lifetime. */
EXPECT_EQ(0, remove_path(UPPER_BASE));
- set_cap(_metadata, CAP_SYS_ADMIN);
- EXPECT_EQ(0, umount(MERGE_DATA));
- clear_cap(_metadata, CAP_SYS_ADMIN);
+ /* umount(MERGE_DATA)) is handled by namespace lifetime. */
EXPECT_EQ(0, remove_path(MERGE_DATA));
cleanup_layout(_metadata);
@@ -4691,6 +4687,8 @@ FIXTURE_SETUP(layout3_fs)
SKIP(return, "this filesystem is not supported (setup)");
}
+ _metadata->teardown_parent = true;
+
slash = strrchr(variant->file_path, '/');
ASSERT_NE(slash, NULL);
dir_len = (size_t)slash - (size_t)variant->file_path;
--
2.44.0
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