[PATCH 2/2] selftests: add test for clone3() with set_tid

Adrian Reber
2019-07-29T16:34:39Z

This tests clone3() with set_tid to see if all desired PIDs are working
as expected. The test tries to clone3() with a set_tid of -1, 1,
pid_max, a PID which is already in use and an unused PID. The same
tests are also running in PID namespace.

Signed-off-by: Adrian Reber <areber@redhat.com>
---
tools/testing/selftests/clone3/.gitignore | 1 +
tools/testing/selftests/clone3/Makefile | 11 ++
.../testing/selftests/clone3/clone3_set_tid.c | 148 ++++++++++++++++++
3 files changed, 160 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_set_tid.c

diff --git a/tools/testing/selftests/clone3/.gitignore b/tools/testing/selftests/clone3/.gitignore
new file mode 100644
index 000000000000..09ccea33016c
--- /dev/null
+++ b/tools/testing/selftests/clone3/.gitignore
@@ -0,0 +1 @@
+clone3_set_tid
diff --git a/tools/testing/selftests/clone3/Makefile b/tools/testing/selftests/clone3/Makefile
new file mode 100644
index 000000000000..45c77b50f367
--- /dev/null
+++ b/tools/testing/selftests/clone3/Makefile
@@ -0,0 +1,11 @@
+# SPDX-License-Identifier: GPL-2.0
+uname_M := $(shell uname -m 2>/dev/null || echo not)
+ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/)
+
+CFLAGS += -I../../../../usr/include/
+
+ifeq ($(ARCH),x86_64)
+ TEST_GEN_PROGS := clone3_set_tid
+endif
+
+include ../lib.mk
diff --git a/tools/testing/selftests/clone3/clone3_set_tid.c b/tools/testing/selftests/clone3/clone3_set_tid.c
new file mode 100644
index 000000000000..1ed0845aa4c5
--- /dev/null
+++ b/tools/testing/selftests/clone3/clone3_set_tid.c
@@ -0,0 +1,148 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+/* Based on Christian Brauner's clone3() example */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/syscall.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <sys/wait.h>
+#include <unistd.h>
+#include <sched.h>
+
+#include "../kselftest.h"
+
+static pid_t raw_clone(struct clone_args *args)
+{
+ return syscall(__NR_clone3, args, sizeof(struct clone_args));
+}
+
+static int call_clone3_set_tid(int set_tid, int flags)
+{
+ struct clone_args args = {0};
+ pid_t ppid = -1;
+ pid_t pid = -1;
+ int status;
+
+ args.flags = flags | CLONE_SET_TID;
+ args.exit_signal = SIGCHLD;
+ args.set_tid = set_tid;
+
+ pid = raw_clone(&args);
+ if (pid < 0) {
+ ksft_print_msg("%s - Failed to create new process\n",
+ strerror(errno));
+ return -errno;
+ }
+
+ if (pid == 0) {
+ ksft_print_msg("I am the child, my PID is %d\n", getpid());
+ if (set_tid != getpid())
+ _exit(EXIT_FAILURE);
+ _exit(EXIT_SUCCESS);
+ }
+
+ ppid = getpid();
+ ksft_print_msg("I am the parent (%d). My child's pid is %d\n",
+ ppid, pid);
+
+ (void)wait(&status);
+ if (WEXITSTATUS(status))
+ return WEXITSTATUS(status);
+
+ return 0;
+}
+
+static int test_clone3_set_tid(int set_tid, int flags, int expected)
+{
+ int ret;
+ ksft_print_msg("[%d] Trying clone3() with CLONE_SET_TID to %d "
+ "and 0x%x\n", getpid(), set_tid, flags);
+ ret = call_clone3_set_tid(set_tid, flags);
+ ksft_print_msg("[%d] clone3() with CLONE_SET_TID %d says :%d "
+ "- expected %d\n", getpid(), set_tid, ret, expected);
+ if (ret != expected)
+ ksft_exit_fail_msg("[%d] Result (%d) is different than "
+ "expected (%d)\n", getpid(), ret, expected);
+ ksft_test_result_pass("[%d] Result (%d) matches expectation (%d)\n",
+ getpid(), ret, expected);
+ return 0;
+}
+int main(int argc, char *argv[])
+{
+ FILE *f;
+ int pid_max = 0;
+ pid_t pid;
+ pid_t ns_pid;
+ int ret = -1;
+
+ ksft_print_header();
+ ksft_set_plan(10);
+
+ f = fopen("/proc/sys/kernel/pid_max", "r");
+ if (f == NULL)
+ ksft_exit_fail_msg("%s - Could not open /proc/sys/kernel/pid_max\n",
+ strerror(errno));
+ fscanf(f, "%d", &pid_max);
+ fclose(f);
+ ksft_print_msg("/proc/sys/kernel/pid_max %d\n", pid_max);
+
+ /* First try with an invalid PID */
+ if (test_clone3_set_tid(-1, 0, -EINVAL))
+ goto on_error;
+ if (test_clone3_set_tid(-1, CLONE_NEWPID, -EINVAL))
+ goto on_error;
+ /* Then with PID 1 */
+ if (test_clone3_set_tid(1, 0, -EAGAIN))
+ goto on_error;
+ /* PID 1 should not fail in a PID namespace */
+ if (test_clone3_set_tid(1, CLONE_NEWPID, 0))
+ goto on_error;
+ /* pid_max should fail everywhere */
+ if (test_clone3_set_tid(pid_max, 0, -EINVAL))
+ goto on_error;
+ if (test_clone3_set_tid(pid_max, CLONE_NEWPID, -EINVAL))
+ goto on_error;
+ /* Find the current active PID */
+ pid = fork();
+ if (pid == 0) {
+ ksft_print_msg("Child has PID %d\n", getpid());
+ sleep(1);
+ _exit(EXIT_SUCCESS);
+ }
+ /* Try to create a process with that PID should fail */
+ if (test_clone3_set_tid(pid, 0, -EAGAIN))
+ goto on_error;
+ (void)wait(NULL);
+ /* After the child has finished, try again with the same PID */
+ if (test_clone3_set_tid(pid, 0, 0))
+ goto on_error;
+ /* This should fail as there is no PID 1 in that namespace */
+ if (test_clone3_set_tid(pid, CLONE_NEWPID, -EINVAL))
+ goto on_error;
+ unshare(CLONE_NEWPID);
+ /* Let's create a PID 1 */
+ ns_pid = fork();
+ if (ns_pid == 0) {
+ ksft_print_msg("Child in PID namespace has PID %d\n", getpid());
+ sleep(1);
+ _exit(EXIT_SUCCESS);
+ }
+ /*
+ * Now, after the unshare() it should be possible to create a process
+ * with another ID than 1 in the PID namespace.
+ */
+ if (test_clone3_set_tid(2, 0, 0))
+ goto on_error;
+ (void)wait(NULL);
+
+ ret = 0;
+on_error:
+
+ return !ret ? ksft_exit_pass() : ksft_exit_fail();
+}
--
2.21.0