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linux-7.2.3/tools/testing/selftests/clone3/.gitignore

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: GPL-2.0-only
+clone3
+clone3_clear_sighand
+clone3_set_tid
+clone3_cap_checkpoint_restore

linux-7.2.3/tools/testing/selftests/clone3/Makefile

@@ -0,0 +1,8 @@
+# SPDX-License-Identifier: GPL-2.0
+CFLAGS += -g -std=gnu99 $(KHDR_INCLUDES)
+LDLIBS += -lcap
+
+TEST_GEN_PROGS := clone3 clone3_clear_sighand clone3_set_tid \
+	clone3_cap_checkpoint_restore
+
+include ../lib.mk

linux-7.2.3/tools/testing/selftests/clone3/clone3.c

@@ -0,0 +1,342 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/* Based on Christian Brauner's clone3() example */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <inttypes.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <stdbool.h>
+#include <stdint.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"
+#include "clone3_selftests.h"
+
+enum test_mode {
+	CLONE3_ARGS_NO_TEST,
+	CLONE3_ARGS_ALL_0,
+	CLONE3_ARGS_INVAL_EXIT_SIGNAL_BIG,
+	CLONE3_ARGS_INVAL_EXIT_SIGNAL_NEG,
+	CLONE3_ARGS_INVAL_EXIT_SIGNAL_CSIG,
+	CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG,
+};
+
+static int call_clone3(uint64_t flags, size_t size, enum test_mode test_mode)
+{
+	struct __clone_args args = {
+		.flags = flags,
+		.exit_signal = SIGCHLD,
+	};
+
+	struct clone_args_extended {
+		struct __clone_args args;
+		__aligned_u64 excess_space[2];
+	} args_ext;
+
+	pid_t pid = -1;
+	int status;
+
+	memset(&args_ext, 0, sizeof(args_ext));
+	if (size > sizeof(struct __clone_args))
+		args_ext.excess_space[1] = 1;
+
+	if (size == 0)
+		size = sizeof(struct __clone_args);
+
+	switch (test_mode) {
+	case CLONE3_ARGS_NO_TEST:
+		/*
+		 * Uses default 'flags' and 'SIGCHLD'
+		 * assignment.
+		 */
+		break;
+	case CLONE3_ARGS_ALL_0:
+		args.flags = 0;
+		args.exit_signal = 0;
+		break;
+	case CLONE3_ARGS_INVAL_EXIT_SIGNAL_BIG:
+		args.exit_signal = 0xbadc0ded00000000ULL;
+		break;
+	case CLONE3_ARGS_INVAL_EXIT_SIGNAL_NEG:
+		args.exit_signal = 0x0000000080000000ULL;
+		break;
+	case CLONE3_ARGS_INVAL_EXIT_SIGNAL_CSIG:
+		args.exit_signal = 0x0000000000000100ULL;
+		break;
+	case CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG:
+		args.exit_signal = 0x00000000000000f0ULL;
+		break;
+	}
+
+	memcpy(&args_ext.args, &args, sizeof(struct __clone_args));
+
+	pid = sys_clone3((struct __clone_args *)&args_ext, size);
+	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);
+	}
+
+	ksft_print_msg("I am the parent (%d). My child's pid is %d\n",
+			getpid(), pid);
+
+	if (waitpid(-1, &status, __WALL) < 0) {
+		ksft_print_msg("waitpid() returned %s\n", strerror(errno));
+		return -errno;
+	}
+	if (!WIFEXITED(status)) {
+		ksft_print_msg("Child did not exit normally, status 0x%x\n",
+			       status);
+		return EXIT_FAILURE;
+	}
+	if (WEXITSTATUS(status))
+		return WEXITSTATUS(status);
+
+	return 0;
+}
+
+static bool test_clone3(uint64_t flags, size_t size, int expected,
+			enum test_mode test_mode)
+{
+	int ret;
+
+	ksft_print_msg(
+		"[%d] Trying clone3() with flags %#" PRIx64 " (size %zu)\n",
+		getpid(), flags, size);
+	ret = call_clone3(flags, size, test_mode);
+	ksft_print_msg("[%d] clone3() with flags says: %d expected %d\n",
+			getpid(), ret, expected);
+	if (ret != expected) {
+		ksft_print_msg(
+			"[%d] Result (%d) is different than expected (%d)\n",
+			getpid(), ret, expected);
+		return false;
+	}
+
+	return true;
+}
+
+typedef bool (*filter_function)(void);
+typedef size_t (*size_function)(void);
+
+static bool not_root(void)
+{
+	if (getuid() != 0) {
+		ksft_print_msg("Not running as root\n");
+		return true;
+	}
+
+	return false;
+}
+
+static bool no_timenamespace(void)
+{
+	if (not_root())
+		return true;
+
+	if (!access("/proc/self/ns/time", F_OK))
+		return false;
+
+	ksft_print_msg("Time namespaces are not supported\n");
+	return true;
+}
+
+static size_t page_size_plus_8(void)
+{
+	return getpagesize() + 8;
+}
+
+struct test {
+	const char *name;
+	uint64_t flags;
+	size_t size;
+	size_function size_function;
+	int expected;
+	enum test_mode test_mode;
+	filter_function filter;
+};
+
+static const struct test tests[] = {
+	{
+		.name = "simple clone3()",
+		.flags = 0,
+		.size = 0,
+		.expected = 0,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+	},
+	{
+		.name = "clone3() in a new PID_NS",
+		.flags = CLONE_NEWPID,
+		.size = 0,
+		.expected = 0,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+		.filter = not_root,
+	},
+	{
+		.name = "CLONE_ARGS_SIZE_VER0",
+		.flags = 0,
+		.size = CLONE_ARGS_SIZE_VER0,
+		.expected = 0,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+	},
+	{
+		.name = "CLONE_ARGS_SIZE_VER0 - 8",
+		.flags = 0,
+		.size = CLONE_ARGS_SIZE_VER0 - 8,
+		.expected = -EINVAL,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+	},
+	{
+		.name = "sizeof(struct clone_args) + 8",
+		.flags = 0,
+		.size = sizeof(struct __clone_args) + 8,
+		.expected = 0,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+	},
+	{
+		.name = "exit_signal with highest 32 bits non-zero",
+		.flags = 0,
+		.size = 0,
+		.expected = -EINVAL,
+		.test_mode = CLONE3_ARGS_INVAL_EXIT_SIGNAL_BIG,
+	},
+	{
+		.name = "negative 32-bit exit_signal",
+		.flags = 0,
+		.size = 0,
+		.expected = -EINVAL,
+		.test_mode = CLONE3_ARGS_INVAL_EXIT_SIGNAL_NEG,
+	},
+	{
+		.name = "exit_signal not fitting into CSIGNAL mask",
+		.flags = 0,
+		.size = 0,
+		.expected = -EINVAL,
+		.test_mode = CLONE3_ARGS_INVAL_EXIT_SIGNAL_CSIG,
+	},
+	{
+		.name = "NSIG < exit_signal < CSIG",
+		.flags = 0,
+		.size = 0,
+		.expected = -EINVAL,
+		.test_mode = CLONE3_ARGS_INVAL_EXIT_SIGNAL_NSIG,
+	},
+	{
+		.name = "Arguments sizeof(struct clone_args) + 8",
+		.flags = 0,
+		.size = sizeof(struct __clone_args) + 8,
+		.expected = 0,
+		.test_mode = CLONE3_ARGS_ALL_0,
+	},
+	{
+		.name = "Arguments sizeof(struct clone_args) + 16",
+		.flags = 0,
+		.size = sizeof(struct __clone_args) + 16,
+		.expected = -E2BIG,
+		.test_mode = CLONE3_ARGS_ALL_0,
+	},
+	{
+		.name = "Arguments sizeof(struct clone_arg) * 2",
+		.flags = 0,
+		.size = sizeof(struct __clone_args) + 16,
+		.expected = -E2BIG,
+		.test_mode = CLONE3_ARGS_ALL_0,
+	},
+	{
+		.name = "Arguments > page size",
+		.flags = 0,
+		.size_function = page_size_plus_8,
+		.expected = -E2BIG,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+	},
+	{
+		.name = "CLONE_ARGS_SIZE_VER0 in a new PID NS",
+		.flags = CLONE_NEWPID,
+		.size = CLONE_ARGS_SIZE_VER0,
+		.expected = 0,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+		.filter = not_root,
+	},
+	{
+		.name = "CLONE_ARGS_SIZE_VER0 - 8 in a new PID NS",
+		.flags = CLONE_NEWPID,
+		.size = CLONE_ARGS_SIZE_VER0 - 8,
+		.expected = -EINVAL,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+	},
+	{
+		.name = "sizeof(struct clone_args) + 8 in a new PID NS",
+		.flags = CLONE_NEWPID,
+		.size = sizeof(struct __clone_args) + 8,
+		.expected = 0,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+		.filter = not_root,
+	},
+	{
+		.name = "Arguments > page size in a new PID NS",
+		.flags = CLONE_NEWPID,
+		.size_function = page_size_plus_8,
+		.expected = -E2BIG,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+	},
+	{
+		.name = "New time NS",
+		.flags = CLONE_NEWTIME,
+		.size = 0,
+		.expected = 0,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+		.filter = no_timenamespace,
+	},
+	{
+		.name = "exit signal (SIGCHLD) in flags",
+		.flags = SIGCHLD,
+		.size = 0,
+		.expected = -EINVAL,
+		.test_mode = CLONE3_ARGS_NO_TEST,
+	},
+};
+
+int main(int argc, char *argv[])
+{
+	size_t size;
+	int i;
+
+	ksft_print_header();
+	ksft_set_plan(ARRAY_SIZE(tests));
+	test_clone3_supported();
+
+	for (i = 0; i < ARRAY_SIZE(tests); i++) {
+		if (tests[i].filter && tests[i].filter()) {
+			ksft_test_result_skip("%s\n", tests[i].name);
+			continue;
+		}
+
+		if (tests[i].size_function)
+			size = tests[i].size_function();
+		else
+			size = tests[i].size;
+
+		ksft_print_msg("Running test '%s'\n", tests[i].name);
+
+		ksft_test_result(test_clone3(tests[i].flags, size,
+					     tests[i].expected,
+					     tests[i].test_mode),
+				 "%s\n", tests[i].name);
+	}
+
+	ksft_finished();
+}

linux-7.2.3/tools/testing/selftests/clone3/clone3_cap_checkpoint_restore.c

@@ -0,0 +1,164 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Based on Christian Brauner's clone3() example.
+ * These tests are assuming to be running in the host's
+ * PID namespace.
+ */
+
+/* capabilities related code based on selftests/bpf/test_verifier.c */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <sys/capability.h>
+#include <sys/prctl.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_harness.h"
+#include "clone3_selftests.h"
+
+static void child_exit(int ret)
+{
+	fflush(stdout);
+	fflush(stderr);
+	_exit(ret);
+}
+
+static int call_clone3_set_tid(struct __test_metadata *_metadata,
+			       pid_t *set_tid, size_t set_tid_size)
+{
+	int status;
+	pid_t pid = -1;
+
+	struct __clone_args args = {
+		.exit_signal = SIGCHLD,
+		.set_tid = ptr_to_u64(set_tid),
+		.set_tid_size = set_tid_size,
+	};
+
+	pid = sys_clone3(&args, sizeof(args));
+	if (pid < 0) {
+		TH_LOG("%s - Failed to create new process", strerror(errno));
+		return -errno;
+	}
+
+	if (pid == 0) {
+		TH_LOG("I am the child, my PID is %d (expected %d)", getpid(), set_tid[0]);
+
+		if (set_tid[0] != getpid())
+			child_exit(EXIT_FAILURE);
+		child_exit(EXIT_SUCCESS);
+	}
+
+	TH_LOG("I am the parent (%d). My child's pid is %d", getpid(), pid);
+
+	if (waitpid(pid, &status, 0) < 0) {
+		TH_LOG("Child returned %s", strerror(errno));
+		return -errno;
+	}
+
+	if (!WIFEXITED(status))
+		return -1;
+
+	return WEXITSTATUS(status);
+}
+
+static int test_clone3_set_tid(struct __test_metadata *_metadata,
+			       pid_t *set_tid, size_t set_tid_size)
+{
+	int ret;
+
+	TH_LOG("[%d] Trying clone3() with CLONE_SET_TID to %d", getpid(), set_tid[0]);
+	ret = call_clone3_set_tid(_metadata, set_tid, set_tid_size);
+	TH_LOG("[%d] clone3() with CLONE_SET_TID %d says:%d", getpid(), set_tid[0], ret);
+	return ret;
+}
+
+static int set_capability(void)
+{
+	cap_value_t cap_values[] = {
+		CAP_SETUID, CAP_SETGID, CAP_CHECKPOINT_RESTORE
+	};
+	int ret = -1;
+	cap_t caps;
+
+	caps = cap_get_proc();
+	if (!caps) {
+		perror("cap_get_proc");
+		return -1;
+	}
+
+	/* Drop all capabilities */
+	if (cap_clear(caps)) {
+		perror("cap_clear");
+		goto out;
+	}
+
+	cap_set_flag(caps, CAP_EFFECTIVE, 3, cap_values, CAP_SET);
+	cap_set_flag(caps, CAP_PERMITTED, 3, cap_values, CAP_SET);
+
+	if (cap_set_proc(caps)) {
+		perror("cap_set_proc");
+		goto out;
+	}
+	ret = 0;
+out:
+	if (cap_free(caps))
+		perror("cap_free");
+	return ret;
+}
+
+TEST(clone3_cap_checkpoint_restore)
+{
+	pid_t pid;
+	int status;
+	pid_t set_tid[1];
+
+	test_clone3_supported();
+
+	EXPECT_EQ(getuid(), 0)
+		SKIP(return, "Skipping all tests as non-root");
+
+	memset(&set_tid, 0, sizeof(set_tid));
+
+	/* Find the current active PID */
+	pid = fork();
+	if (pid == 0) {
+		TH_LOG("Child has PID %d", getpid());
+		child_exit(EXIT_SUCCESS);
+	}
+	ASSERT_GT(waitpid(pid, &status, 0), 0)
+		TH_LOG("Waiting for child %d failed", pid);
+
+	/* After the child has finished, its PID should be free. */
+	set_tid[0] = pid;
+
+	ASSERT_EQ(set_capability(), 0)
+		TH_LOG("Could not set CAP_CHECKPOINT_RESTORE");
+
+	ASSERT_EQ(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0), 0);
+
+	EXPECT_EQ(setgid(65534), 0)
+		TH_LOG("Failed to setgid(65534)");
+	ASSERT_EQ(setuid(65534), 0);
+
+	set_tid[0] = pid;
+	/* This would fail without CAP_CHECKPOINT_RESTORE */
+	ASSERT_EQ(test_clone3_set_tid(_metadata, set_tid, 1), -EPERM);
+	ASSERT_EQ(set_capability(), 0)
+		TH_LOG("Could not set CAP_CHECKPOINT_RESTORE");
+	/* This should work as we have CAP_CHECKPOINT_RESTORE as non-root */
+	ASSERT_EQ(test_clone3_set_tid(_metadata, set_tid, 1), 0);
+}
+
+TEST_HARNESS_MAIN

linux-7.2.3/tools/testing/selftests/clone3/clone3_clear_sighand.c

@@ -0,0 +1,124 @@
+/* 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"
+#include "clone3_selftests.h"
+
+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();
+
+	ksft_exit_pass();
+}

linux-7.2.3/tools/testing/selftests/clone3/clone3_selftests.h

@@ -0,0 +1,69 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#ifndef _CLONE3_SELFTESTS_H
+#define _CLONE3_SELFTESTS_H
+
+#define _GNU_SOURCE
+#include <sched.h>
+#include <linux/sched.h>
+#include <linux/types.h>
+#include <stdint.h>
+#include <syscall.h>
+#include <sys/wait.h>
+
+#include "kselftest.h"
+
+#define ptr_to_u64(ptr) ((__u64)((uintptr_t)(ptr)))
+
+#ifndef __NR_clone3
+#define __NR_clone3 435
+#endif
+
+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;
+	__aligned_u64 set_tid;
+	__aligned_u64 set_tid_size;
+	__aligned_u64 cgroup;
+};
+
+static pid_t sys_clone3(struct __clone_args *args, size_t size)
+{
+	fflush(stdout);
+	fflush(stderr);
+	return syscall(__NR_clone3, args, size);
+}
+
+static inline 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");
+}
+
+#endif /* _CLONE3_SELFTESTS_H */

linux-7.2.3/tools/testing/selftests/clone3/clone3_set_tid.c

@@ -0,0 +1,418 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Based on Christian Brauner's clone3() example.
+ * These tests are assuming to be running in the host's
+ * PID namespace.
+ */
+
+#define _GNU_SOURCE
+#include <errno.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.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"
+#include "clone3_selftests.h"
+
+#define MAX_PID_NS_LEVEL 32
+
+static int pipe_1[2];
+static int pipe_2[2];
+
+static void child_exit(int ret)
+{
+	fflush(stdout);
+	fflush(stderr);
+	_exit(ret);
+}
+
+static int call_clone3_set_tid(pid_t *set_tid,
+			       size_t set_tid_size,
+			       int flags,
+			       int expected_pid,
+			       bool wait_for_it)
+{
+	int status;
+	pid_t pid = -1;
+
+	struct __clone_args args = {
+		.flags = flags,
+		.exit_signal = SIGCHLD,
+		.set_tid = ptr_to_u64(set_tid),
+		.set_tid_size = set_tid_size,
+	};
+
+	pid = sys_clone3(&args, sizeof(args));
+	if (pid < 0) {
+		ksft_print_msg("%s - Failed to create new process\n",
+			       strerror(errno));
+		return -errno;
+	}
+
+	if (pid == 0) {
+		int ret;
+		char tmp = 0;
+		int exit_code = EXIT_SUCCESS;
+
+		ksft_print_msg("I am the child, my PID is %d (expected %d)\n",
+			       getpid(), set_tid[0]);
+		if (wait_for_it) {
+			ksft_print_msg("[%d] Child is ready and waiting\n",
+				       getpid());
+
+			/* Signal the parent that the child is ready */
+			close(pipe_1[0]);
+			ret = write(pipe_1[1], &tmp, 1);
+			if (ret != 1) {
+				ksft_print_msg(
+					"Writing to pipe returned %d", ret);
+				exit_code = EXIT_FAILURE;
+			}
+			close(pipe_1[1]);
+			close(pipe_2[1]);
+			ret = read(pipe_2[0], &tmp, 1);
+			if (ret != 1) {
+				ksft_print_msg(
+					"Reading from pipe returned %d", ret);
+				exit_code = EXIT_FAILURE;
+			}
+			close(pipe_2[0]);
+		}
+
+		if (set_tid[0] != getpid())
+			child_exit(EXIT_FAILURE);
+		child_exit(exit_code);
+	}
+
+	if (expected_pid == 0 || expected_pid == pid) {
+		ksft_print_msg("I am the parent (%d). My child's pid is %d\n",
+			       getpid(), pid);
+	} else {
+		ksft_print_msg(
+			"Expected child pid %d does not match actual pid %d\n",
+			expected_pid, pid);
+		return -1;
+	}
+
+	if (waitpid(pid, &status, 0) < 0) {
+		ksft_print_msg("Child returned %s\n", strerror(errno));
+		return -errno;
+	}
+
+	if (!WIFEXITED(status))
+		return -1;
+
+	return WEXITSTATUS(status);
+}
+
+static void test_clone3_set_tid(const char *desc,
+				pid_t *set_tid,
+				size_t set_tid_size,
+				int flags,
+				int expected,
+				int expected_pid,
+				bool wait_for_it)
+{
+	int ret;
+
+	ksft_print_msg(
+		"[%d] Trying clone3() with CLONE_SET_TID to %d and 0x%x\n",
+		getpid(), set_tid[0], flags);
+	ret = call_clone3_set_tid(set_tid, set_tid_size, flags, expected_pid,
+				  wait_for_it);
+	ksft_print_msg(
+		"[%d] clone3() with CLONE_SET_TID %d says: %d - expected %d\n",
+		getpid(), set_tid[0], ret, expected);
+
+	ksft_test_result(ret == expected, "%s with %zu TIDs and flags 0x%x\n",
+			 desc, set_tid_size, flags);
+}
+
+int main(int argc, char *argv[])
+{
+	FILE *f;
+	char buf;
+	char *line = NULL;
+	int status;
+	int ret = -1;
+	size_t len = 0;
+	int pid_max = 0;
+	uid_t uid = getuid();
+	char proc_path[100] = {0};
+	pid_t pid, ns1, ns2, ns3, ns_pid;
+	pid_t set_tid[MAX_PID_NS_LEVEL * 2];
+
+	ksft_print_header();
+	ksft_set_plan(29);
+	test_clone3_supported();
+
+	if (pipe(pipe_1) < 0 || pipe(pipe_2) < 0)
+		ksft_exit_fail_msg("pipe() failed\n");
+
+	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);
+
+	/* Try invalid settings */
+	memset(&set_tid, 0, sizeof(set_tid));
+	test_clone3_set_tid("invalid size, 0 TID",
+			    set_tid, MAX_PID_NS_LEVEL + 1, 0, -EINVAL, 0, 0);
+
+	test_clone3_set_tid("invalid size, 0 TID",
+			    set_tid, MAX_PID_NS_LEVEL * 2, 0, -EINVAL, 0, 0);
+
+	test_clone3_set_tid("invalid size, 0 TID",
+			    set_tid, MAX_PID_NS_LEVEL * 2 + 1, 0,
+			    -EINVAL, 0, 0);
+
+	test_clone3_set_tid("invalid size, 0 TID",
+			    set_tid, MAX_PID_NS_LEVEL * 42, 0, -EINVAL, 0, 0);
+
+	/*
+	 * This can actually work if this test running in a MAX_PID_NS_LEVEL - 1
+	 * nested PID namespace.
+	 */
+	test_clone3_set_tid("invalid size, 0 TID",
+			    set_tid, MAX_PID_NS_LEVEL - 1, 0, -EINVAL, 0, 0);
+
+	memset(&set_tid, 0xff, sizeof(set_tid));
+	test_clone3_set_tid("invalid size, TID all 1s",
+			    set_tid, MAX_PID_NS_LEVEL + 1, 0, -EINVAL, 0, 0);
+
+	test_clone3_set_tid("invalid size, TID all 1s",
+			    set_tid, MAX_PID_NS_LEVEL * 2, 0, -EINVAL, 0, 0);
+
+	test_clone3_set_tid("invalid size, TID all 1s",
+			    set_tid, MAX_PID_NS_LEVEL * 2 + 1, 0,
+			    -EINVAL, 0, 0);
+
+	test_clone3_set_tid("invalid size, TID all 1s",
+			    set_tid, MAX_PID_NS_LEVEL * 42, 0, -EINVAL, 0, 0);
+
+	/*
+	 * This can actually work if this test running in a MAX_PID_NS_LEVEL - 1
+	 * nested PID namespace.
+	 */
+	test_clone3_set_tid("invalid size, TID all 1s",
+			    set_tid, MAX_PID_NS_LEVEL - 1, 0, -EINVAL, 0, 0);
+
+	memset(&set_tid, 0, sizeof(set_tid));
+	/* Try with an invalid PID */
+	set_tid[0] = 0;
+	test_clone3_set_tid("valid size, 0 TID",
+			    set_tid, 1, 0, -EINVAL, 0, 0);
+
+	set_tid[0] = -1;
+	test_clone3_set_tid("valid size, -1 TID",
+			    set_tid, 1, 0, -EINVAL, 0, 0);
+
+	/* Claim that the set_tid array actually contains 2 elements. */
+	test_clone3_set_tid("2 TIDs, -1 and 0",
+			    set_tid, 2, 0, -EINVAL, 0, 0);
+
+	/* Try it in a new PID namespace */
+	if (uid == 0)
+		test_clone3_set_tid("valid size, -1 TID",
+				    set_tid, 1, CLONE_NEWPID, -EINVAL, 0, 0);
+	else
+		ksft_test_result_skip("Clone3() with set_tid requires root\n");
+
+	/* Try with a valid PID (1) this should return -EEXIST. */
+	set_tid[0] = 1;
+	if (uid == 0)
+		test_clone3_set_tid("duplicate PID 1",
+				    set_tid, 1, 0, -EEXIST, 0, 0);
+	else
+		ksft_test_result_skip("Clone3() with set_tid requires root\n");
+
+	/* Try it in a new PID namespace */
+	if (uid == 0)
+		test_clone3_set_tid("duplicate PID 1",
+				    set_tid, 1, CLONE_NEWPID, 0, 0, 0);
+	else
+		ksft_test_result_skip("Clone3() with set_tid requires root\n");
+
+	/* pid_max should fail everywhere */
+	set_tid[0] = pid_max;
+	test_clone3_set_tid("set TID to maximum",
+			    set_tid, 1, 0, -EINVAL, 0, 0);
+
+	if (uid == 0)
+		test_clone3_set_tid("set TID to maximum",
+				    set_tid, 1, CLONE_NEWPID, -EINVAL, 0, 0);
+	else
+		ksft_test_result_skip("Clone3() with set_tid requires root\n");
+
+	if (uid != 0) {
+		/*
+		 * All remaining tests require root. Tell the framework
+		 * that all those tests are skipped as non-root.
+		 */
+		ksft_cnt.ksft_xskip += ksft_plan - ksft_test_num();
+		goto out;
+	}
+
+	/* Find the current active PID */
+	pid = fork();
+	if (pid == 0) {
+		ksft_print_msg("Child has PID %d\n", getpid());
+		child_exit(EXIT_SUCCESS);
+	}
+	if (waitpid(pid, &status, 0) < 0)
+		ksft_exit_fail_msg("Waiting for child %d failed", pid);
+
+	/* After the child has finished, its PID should be free. */
+	set_tid[0] = pid;
+	test_clone3_set_tid("reallocate child TID",
+			    set_tid, 1, 0, 0, 0, 0);
+
+	/* This should fail as there is no PID 1 in that namespace */
+	test_clone3_set_tid("duplicate child TID",
+			    set_tid, 1, CLONE_NEWPID, -EINVAL, 0, 0);
+
+	/*
+	 * Creating a process with PID 1 in the newly created most nested
+	 * PID namespace and PID 'pid' in the parent PID namespace. This
+	 * needs to work.
+	 */
+	set_tid[0] = 1;
+	set_tid[1] = pid;
+	test_clone3_set_tid("create PID 1 in new NS",
+			    set_tid, 2, CLONE_NEWPID, 0, pid, 0);
+
+	ksft_print_msg("unshare PID namespace\n");
+	if (unshare(CLONE_NEWPID) == -1)
+		ksft_exit_fail_msg("unshare(CLONE_NEWPID) failed: %s\n",
+				strerror(errno));
+
+	set_tid[0] = pid;
+
+	/* This should fail as there is no PID 1 in that namespace */
+	test_clone3_set_tid("duplicate PID 1",
+			    set_tid, 1, 0, -EINVAL, 0, 0);
+
+	/* Let's create a PID 1 */
+	ns_pid = fork();
+	if (ns_pid == 0) {
+		/*
+		 * This and the next test cases check that all pid-s are
+		 * released on error paths.
+		 */
+		set_tid[0] = 43;
+		set_tid[1] = -1;
+		test_clone3_set_tid("check leak on invalid TID -1",
+				    set_tid, 2, 0, -EINVAL, 0, 0);
+
+		set_tid[0] = 43;
+		set_tid[1] = pid;
+		test_clone3_set_tid("check leak on invalid specific TID",
+				    set_tid, 2, 0, 0, 43, 0);
+
+		ksft_print_msg("Child in PID namespace has PID %d\n", getpid());
+		set_tid[0] = 2;
+		test_clone3_set_tid("create PID 2 in child NS",
+				    set_tid, 1, 0, 0, 2, 0);
+
+		set_tid[0] = 1;
+		set_tid[1] = -1;
+		set_tid[2] = pid;
+		/* This should fail as there is invalid PID at level '1'. */
+		test_clone3_set_tid("fail due to invalid TID at level 1",
+				    set_tid, 3, CLONE_NEWPID, -EINVAL, 0, 0);
+
+		set_tid[0] = 1;
+		set_tid[1] = 42;
+		set_tid[2] = pid;
+		/*
+		 * This should fail as there are not enough active PID
+		 * namespaces. Again assuming this is running in the host's
+		 * PID namespace. Not yet nested.
+		 */
+		test_clone3_set_tid("fail due to too few active PID NSs",
+				    set_tid, 4, CLONE_NEWPID, -EINVAL, 0, 0);
+
+		/*
+		 * This should work and from the parent we should see
+		 * something like 'NSpid:	pid	42	1'.
+		 */
+		test_clone3_set_tid("verify that we have 3 PID NSs",
+				    set_tid, 3, CLONE_NEWPID, 0, 42, true);
+
+		child_exit(ksft_cnt.ksft_fail);
+	}
+
+	close(pipe_1[1]);
+	close(pipe_2[0]);
+	while (read(pipe_1[0], &buf, 1) > 0) {
+		ksft_print_msg("[%d] Child is ready and waiting\n", getpid());
+		break;
+	}
+
+	snprintf(proc_path, sizeof(proc_path), "/proc/%d/status", pid);
+	f = fopen(proc_path, "r");
+	if (f == NULL)
+		ksft_exit_fail_msg(
+			"%s - Could not open %s\n",
+			strerror(errno), proc_path);
+
+	while (getline(&line, &len, f) != -1) {
+		if (strstr(line, "NSpid")) {
+			int i;
+
+			/* Verify that all generated PIDs are as expected. */
+			i = sscanf(line, "NSpid:\t%d\t%d\t%d",
+				   &ns3, &ns2, &ns1);
+			if (i != 3) {
+				ksft_print_msg(
+					"Unexpected 'NSPid:' entry: %s",
+					line);
+				ns1 = ns2 = ns3 = 0;
+			}
+			break;
+		}
+	}
+	fclose(f);
+	free(line);
+	close(pipe_2[0]);
+
+	/* Tell the clone3()'d child to finish. */
+	write(pipe_2[1], &buf, 1);
+	close(pipe_2[1]);
+
+	if (waitpid(ns_pid, &status, 0) < 0) {
+		ksft_print_msg("Child returned %s\n", strerror(errno));
+		ret = -errno;
+		goto out;
+	}
+
+	if (!WIFEXITED(status))
+		ksft_test_result_fail("Child error\n");
+
+	ksft_cnt.ksft_pass += 6 - (ksft_cnt.ksft_fail - WEXITSTATUS(status));
+	ksft_cnt.ksft_fail = WEXITSTATUS(status);
+
+	ksft_print_msg("Expecting PIDs %d, 42, 1\n", pid);
+	ksft_print_msg("Have PIDs in namespaces: %d, %d, %d\n", ns3, ns2, ns1);
+	ksft_test_result(ns3 == pid && ns2 == 42 && ns1 == 1,
+			 "PIDs in all namespaces as expected\n");
+out:
+	ret = 0;
+
+	if (ret)
+		ksft_exit_fail();
+	ksft_exit_pass();
+}