[PATCH v5 2/2] selftests: add tests for clone3()

[Adrian Reber]

This tests clone3() with and without 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@xxxxxxxxxx>
---
 tools/testing/selftests/clone3/.gitignore     |   2 +
 tools/testing/selftests/clone3/Makefile       |  11 ++
 tools/testing/selftests/clone3/clone3.c       | 141 +++++++++++++++
 .../testing/selftests/clone3/clone3_set_tid.c | 161 ++++++++++++++++++
 4 files changed, 315 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.c
 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..c63c64a78ddf
--- /dev/null
+++ b/tools/testing/selftests/clone3/.gitignore
@@ -0,0 +1,2 @@
+clone3_set_tid
+clone3
diff --git a/tools/testing/selftests/clone3/Makefile b/tools/testing/selftests/clone3/Makefile
new file mode 100644
index 000000000000..4efcf45b995b
--- /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 clone3_set_tid
+endif
+
+include ../lib.mk
diff --git a/tools/testing/selftests/clone3/clone3.c b/tools/testing/selftests/clone3/clone3.c
new file mode 100644
index 000000000000..55a6915566b8
--- /dev/null
+++ b/tools/testing/selftests/clone3/clone3.c
@@ -0,0 +1,141 @@
+// 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(int flags)
+{
+	struct clone_args args = {0};
+	pid_t ppid = -1;
+	pid_t pid = -1;
+	int status;
+
+	args.flags = flags;
+	args.exit_signal = SIGCHLD;
+
+	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());
+		_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(int flags, int expected)
+{
+	int ret;
+
+	ksft_print_msg("[%d] Trying clone3() with flags 0x%x\n",
+			getpid(), flags);
+	ret = call_clone3(flags);
+	ksft_print_msg("[%d] clone3() with flags says :%d expected %d\n",
+			getpid(), 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[])
+{
+	int ret = -1;
+	pid_t pid;
+
+	ksft_print_header();
+	ksft_set_plan(3);
+
+	/* Just a simple clone3() should return 0.*/
+	if (test_clone3(0, 0))
+		goto on_error;
+	/* Do a clone3() in a new PID NS.*/
+	if (test_clone3(CLONE_NEWPID, 0))
+		goto on_error;
+	ksft_print_msg("First unshare\n");
+	if (unshare(CLONE_NEWPID))
+		goto on_error;
+	/*
+	 * Before clone3()ing in a new PID NS with
+	 * CLONE_NEWPID a fork() is necessary.
+	 */
+	if (test_clone3(CLONE_NEWPID, -EINVAL))
+		goto on_error;
+	pid = fork();
+	if (pid < 0) {
+		ksft_print_msg("First fork() failed\n");
+		goto on_error;
+	}
+	if (pid > 0) {
+		(void)wait(NULL);
+		goto parent_out;
+	}
+	ksft_set_plan(6);
+	if (test_clone3(CLONE_NEWPID, 0))
+		goto on_error;
+	if (test_clone3(0, 0))
+		goto on_error;
+	ksft_print_msg("Second unshare\n");
+	if (unshare(CLONE_NEWPID))
+		goto on_error;
+	/*
+	 * Before clone3()ing in a new PID NS with
+	 * CLONE_NEWPID a fork() is necessary.
+	 */
+	if (test_clone3(CLONE_NEWPID, -EINVAL))
+		goto on_error;
+	pid = fork();
+	if (pid < 0) {
+		ksft_print_msg("Second fork() failed\n");
+		goto on_error;
+	}
+	if (pid > 0) {
+		(void)wait(NULL);
+		goto parent_out;
+	}
+	ksft_set_plan(8);
+	if (test_clone3(CLONE_NEWPID, 0))
+		goto on_error;
+	if (test_clone3(0, 0))
+		goto on_error;
+
+parent_out:
+	ret = 0;
+on_error:
+
+	return !ret ? ksft_exit_pass() : ksft_exit_fail();
+}
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..f5012e84dcb3
--- /dev/null
+++ b/tools/testing/selftests/clone3/clone3_set_tid.c
@@ -0,0 +1,161 @@
+// 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;
+	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 (expected %d)\n",
+				getpid(), set_tid);
+		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(13);
+
+	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, -EEXIST))
+		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, -EEXIST))
+		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);
+	if (test_clone3_set_tid(10, 0, -EINVAL))
+		goto on_error;
+	/* 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;
+	/* Use a different PID in this namespace. */
+	if (test_clone3_set_tid(2222, 0, 0))
+		goto on_error;
+	if (test_clone3_set_tid(1, 0, -EEXIST))
+		goto on_error;
+	(void)wait(NULL);
+
+	ret = 0;
+on_error:
+
+	return !ret ? ksft_exit_pass() : ksft_exit_fail();
+}
-- 
2.21.0