tests: test CLONE_CLEAR_SIGHAND

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

Cc: Florian Weimer <fweimer@redhat.com>
Cc: libc-alpha@sourceware.org
Cc: linux-api@vger.kernel.org
Signed-off-by: Christian Brauner <christian.brauner@ubuntu.com>
Link: https://lore.kernel.org/r/20191014104538.3096-2-christian.brauner@ubuntu.com

diff --git a/MAINTAINERS b/MAINTAINERS
index a69e6db..ab09c34 100644 (file)
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -12826,6 +12826,7 @@ 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 4cdbae6..ad44236 100644 (file)
--- 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 (file)
index 0000000..6c9f980
--- /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 (file)
index 0000000..e6f2593
--- /dev/null
+++ b/tools/testing/selftests/clone3/Makefile
@@ -0,0 +1,6 @@
+# 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 (file)
index 0000000..0d957be
--- /dev/null
+++ b/tools/testing/selftests/clone3/clone3_clear_sighand.c
@@ -0,0 +1,172 @@
+/* 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 CLONE_CLEAR_SIGHAND
+#define CLONE_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 act;
+
+       /*
+        * Check that CLONE_CLEAR_SIGHAND and CLONE_SIGHAND are mutually
+        * exclusive.
+        */
+       args.flags |= CLONE_CLEAR_SIGHAND | CLONE_SIGHAND;
+       args.exit_signal = SIGCHLD;
+       pid = sys_clone3(&args, sizeof(args));
+       if (pid > 0)
+               ksft_exit_fail_msg(
+                       "clone3(CLONE_CLEAR_SIGHAND | CLONE_SIGHAND) succeeded\n");
+
+       act.sa_handler = nop_handler;
+       ret = sigemptyset(&act.sa_mask);
+       if (ret < 0)
+               ksft_exit_fail_msg("%s - sigemptyset() failed\n",
+                                  strerror(errno));
+
+       act.sa_flags = 0;
+
+       /* Register signal handler for SIGUSR1 */
+       ret = sigaction(SIGUSR1, &act, NULL);
+       if (ret < 0)
+               ksft_exit_fail_msg(
+                       "%s - sigaction(SIGUSR1, &act, NULL) failed\n",
+                       strerror(errno));
+
+       /* Register signal handler for SIGUSR2 */
+       ret = sigaction(SIGUSR2, &act, NULL);
+       if (ret < 0)
+               ksft_exit_fail_msg(
+                       "%s - sigaction(SIGUSR2, &act, NULL) failed\n",
+                       strerror(errno));
+
+       /* Check that CLONE_CLEAR_SIGHAND works. */
+       args.flags = CLONE_CLEAR_SIGHAND;
+       pid = sys_clone3(&args, sizeof(args));
+       if (pid < 0)
+               ksft_exit_fail_msg("%s - clone3(CLONE_CLEAR_SIGHAND) failed\n",
+                                  strerror(errno));
+
+       if (pid == 0) {
+               ret = sigaction(SIGUSR1, NULL, &act);
+               if (ret < 0)
+                       exit(EXIT_FAILURE);
+
+               if (act.sa_handler != SIG_DFL)
+                       exit(EXIT_FAILURE);
+
+               ret = sigaction(SIGUSR2, NULL, &act);
+               if (ret < 0)
+                       exit(EXIT_FAILURE);
+
+               if (act.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();
+}