// 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;
        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();
}