[PATCH 2/2] tests: test CLONE3_CLEAR_SIGHAND

Christian Brauner
2019-10-10T13:35:40Z

Test that CLONE3_CLEAR_SIGHAND resets signal handlers to SIG_DFL for the
child process and that CLONE3_CLEAR_SIGHAND and CLONE_SIGHAND are
mutually exclusive.

Cc: Florian Weimer <fweimer@redhat.com>
Cc: libc-alpha@sourceware.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
---
MAINTAINERS | 1 +
tools/testing/selftests/Makefile | 1 +
tools/testing/selftests/clone3/.gitignore | 1 +
tools/testing/selftests/clone3/Makefile | 7 +
.../selftests/clone3/clone3_clear_sighand.c | 171 ++++++++++++++++++
5 files changed, 181 insertions(+)
create mode 100644 tools/testing/selftests/clone3/.gitignore
create mode 100644 tools/testing/selftests/clone3/Makefile
create mode 100644 tools/testing/selftests/clone3/clone3_clear_sighand.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 55199ef7fa74..582275d85607 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12828,6 +12828,7 @@ S: Maintained
T: git git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux.git
F: samples/pidfd/
F: tools/testing/selftests/pidfd/
+F: tools/testing/selftests/clone3/
K: (?i)pidfd
K: (?i)clone3
K: \b(clone_args|kernel_clone_args)\b
diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
index c3feccb99ff5..6bf7aeb47650 100644
--- a/tools/testing/selftests/Makefile
+++ b/tools/testing/selftests/Makefile
@@ -4,6 +4,7 @@ TARGETS += bpf
TARGETS += breakpoints
TARGETS += capabilities
TARGETS += cgroup
+TARGETS += clone3
TARGETS += cpufreq
TARGETS += cpu-hotplug
TARGETS += drivers/dma-buf
diff --git a/tools/testing/selftests/clone3/.gitignore b/tools/testing/selftests/clone3/.gitignore
new file mode 100644
index 000000000000..6c9f98097774
--- /dev/null
+++ b/tools/testing/selftests/clone3/.gitignore
@@ -0,0 +1 @@
+clone3_clear_sighand
diff --git a/tools/testing/selftests/clone3/Makefile b/tools/testing/selftests/clone3/Makefile
new file mode 100644
index 000000000000..3ecd56ebc99d
--- /dev/null
+++ b/tools/testing/selftests/clone3/Makefile
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: GPL-2.0-only
+CFLAGS += -g -I../../../../usr/include/
+
+TEST_GEN_PROGS := clone3_clear_sighand
+
+include ../lib.mk
+
diff --git a/tools/testing/selftests/clone3/clone3_clear_sighand.c b/tools/testing/selftests/clone3/clone3_clear_sighand.c
new file mode 100644
index 000000000000..0e38c06dd6eb
--- /dev/null
+++ b/tools/testing/selftests/clone3/clone3_clear_sighand.c
@@ -0,0 +1,171 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <sys/syscall.h>
+#include <sys/wait.h>
+
+#include "../kselftest.h"
+
+#ifndef CLONE3_CLEAR_SIGHAND
+#define CLONE3_CLEAR_SIGHAND 0x100000000ULL
+#endif
+
+#ifndef __NR_clone3
+#define __NR_clone3 -1
+struct clone_args {
+ __aligned_u64 flags;
+ __aligned_u64 pidfd;
+ __aligned_u64 child_tid;
+ __aligned_u64 parent_tid;
+ __aligned_u64 exit_signal;
+ __aligned_u64 stack;
+ __aligned_u64 stack_size;
+ __aligned_u64 tls;
+};
+#endif
+
+static pid_t sys_clone3(struct clone_args *args, size_t size)
+{
+ return syscall(__NR_clone3, args, size);
+}
+
+static void test_clone3_supported(void)
+{
+ pid_t pid;
+ struct clone_args args = {};
+
+ if (__NR_clone3 < 0)
+ ksft_exit_skip("clone3() syscall is not supported\n");
+
+ /* Set to something that will always cause EINVAL. */
+ args.exit_signal = -1;
+ pid = sys_clone3(&args, sizeof(args));
+ if (!pid)
+ exit(EXIT_SUCCESS);
+
+ if (pid > 0) {
+ wait(NULL);
+ ksft_exit_fail_msg(
+ "Managed to create child process with invalid exit_signal\n");
+ }
+
+ if (errno == ENOSYS)
+ ksft_exit_skip("clone3() syscall is not supported\n");
+
+ ksft_print_msg("clone3() syscall supported\n");
+}
+
+static void nop_handler(int signo)
+{
+}
+
+static int wait_for_pid(pid_t pid)
+{
+ int status, ret;
+
+again:
+ ret = waitpid(pid, &status, 0);
+ if (ret == -1) {
+ if (errno == EINTR)
+ goto again;
+
+ return -1;
+ }
+
+ if (!WIFEXITED(status))
+ return -1;
+
+ return WEXITSTATUS(status);
+}
+
+static void test_clone3_clear_sighand(void)
+{
+ int ret;
+ pid_t pid;
+ struct clone_args args = {};
+ struct sigaction new_action, old_action;
+
+ new_action.sa_handler = nop_handler;
+ ret = sigemptyset(&new_action.sa_mask);
+ if (ret < 0)
+ ksft_exit_fail_msg("%s - sigemptyset() failed\n",
+ strerror(errno));
+
+ new_action.sa_flags = 0;
+
+ ret = sigaction(SIGUSR1, &new_action, NULL);
+ if (ret < 0)
+ ksft_exit_fail_msg(
+ "%s - sigaction(SIGUSR1, &new_action, NULL) failed\n",
+ strerror(errno));
+
+ ret = sigaction(SIGUSR2, &new_action, NULL);
+ if (ret < 0)
+ ksft_exit_fail_msg(
+ "%s - sigaction(SIGUSR2, &new_action, NULL) failed\n",
+ strerror(errno));
+
+ /*
+ * Check that CLONE3_CLEAR_SIGHAND and CLONE_SIGHAND are mutually
+ * exclusive.
+ */
+ args.flags |= CLONE3_CLEAR_SIGHAND | CLONE_SIGHAND;
+ args.exit_signal = SIGCHLD;
+ pid = sys_clone3(&args, sizeof(args));
+ if (pid > 0)
+ ksft_exit_fail_msg(
+ "clone3(CLONE3_CLEAR_SIGHAND | CLONE_SIGHAND) succeeded\n");
+
+ /* Check that CLONE3_CLEAR_SIGHAND works. */
+ args.flags = CLONE3_CLEAR_SIGHAND;
+ pid = sys_clone3(&args, sizeof(args));
+ if (pid < 0)
+ ksft_exit_fail_msg("%s - clone3(CLONE3_CLEAR_SIGHAND) failed\n", strerror(errno));
+
+ if (pid == 0) {
+ struct sigaction query_action;
+
+ ret = sigaction(SIGUSR1, NULL, &query_action);
+ if (ret < 0)
+ exit(EXIT_FAILURE);
+
+ if (query_action.sa_handler != SIG_DFL)
+ exit(EXIT_FAILURE);
+
+ ret = sigaction(SIGUSR2, NULL, &query_action);
+ if (ret < 0)
+ exit(EXIT_FAILURE);
+
+ if (query_action.sa_handler != SIG_DFL)
+ exit(EXIT_FAILURE);
+
+ exit(EXIT_SUCCESS);
+ }
+
+ ret = wait_for_pid(pid);
+ if (ret)
+ ksft_exit_fail_msg(
+ "Failed to clear signal handler for child process\n");
+
+ ksft_test_result_pass("Cleared signal handlers for child process\n");
+}
+
+int main(int argc, char **argv)
+{
+ ksft_print_header();
+ ksft_set_plan(1);
+
+ test_clone3_supported();
+ test_clone3_clear_sighand();
+
+ return ksft_exit_pass();
+}
--
2.23.0