selftests: Enhance kselftest_harness.h to print which assert failed

When a test process is not able to write to TH_LOG_STREAM, this step
mechanism enable to print the assert number which triggered the failure.
This can be enabled by setting _metadata->no_print to true at the
beginning of the test sequence.

Update the seccomp-bpf test to return 0 if a test succeeded.

This feature is needed for the Landlock tests.

Signed-off-by: Mickaël Salaün <mic@digikod.net>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Kees Cook <keescook@chromium.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Will Drewry <wad@chromium.org>
Link: https://lkml.kernel.org/r/CAGXu5j+D-FP8Kt9unNOqKrQJP4DYTpmgkJxWykZyrYiVPz3Y3Q@mail.gmail.com
Signed-off-by: Shuah Khan <shuahkh@osg.samsung.com>

diff --git a/tools/testing/selftests/kselftest_harness.h b/tools/testing/selftests/kselftest_harness.h
index c56f72e..e81bd28 100644 (file)
--- a/tools/testing/selftests/kselftest_harness.h
+++ b/tools/testing/selftests/kselftest_harness.h
@@ -51,6 +51,9 @@
 #define __KSELFTEST_HARNESS_H
 
 #define _GNU_SOURCE
+#include <asm/types.h>
+#include <errno.h>
+#include <stdbool.h>
 #include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
@@ -84,6 +87,14 @@
  * 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) \
@@ -555,12 +566,18 @@
  * return while still providing an optional block to the API consumer.
  */
 #define OPTIONAL_HANDLER(_assert) \
-       for (; _metadata->trigger;  _metadata->trigger = __bail(_assert))
+       for (; _metadata->trigger; _metadata->trigger = \
+                       __bail(_assert, _metadata->no_print, _metadata->step))
+
+#define __INC_STEP(_metadata) \
+       if (_metadata->passed && _metadata->step < 255) \
+               _metadata->step++;
 
 #define __EXPECT(_expected, _seen, _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)) { \
                unsigned long long __exp_print = (uintptr_t)__exp; \
                unsigned long long __seen_print = (uintptr_t)__seen; \
@@ -576,6 +593,7 @@
 #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; \
@@ -590,6 +608,8 @@ struct __test_metadata {
        int termsig;
        int passed;
        int trigger; /* extra handler after the evaluation */
+       __u8 step;
+       bool no_print; /* manual trigger when TH_LOG_STREAM is not available */
        struct __test_metadata *prev, *next;
 };
 
@@ -634,10 +654,13 @@ static inline void __register_test(struct __test_metadata *t)
        }
 }
 
-static inline int __bail(int for_realz)
+static inline int __bail(int for_realz, bool no_print, __u8 step)
 {
-       if (for_realz)
+       if (for_realz) {
+               if (no_print)
+                       _exit(step);
                abort();
+       }
        return 0;
 }
 
@@ -655,18 +678,24 @@ void __run_test(struct __test_metadata *t)
                t->passed = 0;
        } else if (child_pid == 0) {
                t->fn(t);
-               _exit(t->passed);
+               /* return the step that failed or 0 */
+               _exit(t->passed ? 0 : t->step);
        } else {
                /* TODO(wad) add timeout support. */
                waitpid(child_pid, &status, 0);
                if (WIFEXITED(status)) {
-                       t->passed = t->termsig == -1 ? WEXITSTATUS(status) : 0;
+                       t->passed = t->termsig == -1 ? !WEXITSTATUS(status) : 0;
                        if (t->termsig != -1) {
                                fprintf(TH_LOG_STREAM,
                                        "%s: Test exited normally "
                                        "instead of by signal (code: %d)\n",
                                        t->name,
                                        WEXITSTATUS(status));
+                       } else if (!t->passed) {
+                               fprintf(TH_LOG_STREAM,
+                                       "%s: Test failed at step #%d\n",
+                                       t->name,
+                                       WEXITSTATUS(status));
                        }
                } else if (WIFSIGNALED(status)) {
                        t->passed = 0;

diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index 73f5ea6..4d6f92a 100644 (file)
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -107,7 +107,7 @@ TEST(mode_strict_support)
        ASSERT_EQ(0, ret) {
                TH_LOG("Kernel does not support CONFIG_SECCOMP");
        }
-       syscall(__NR_exit, 1);
+       syscall(__NR_exit, 0);
 }
 
 TEST_SIGNAL(mode_strict_cannot_call_prctl, SIGKILL)