/* SPDX-License-Identifier: GPL-2.0 */
#define _GNU_SOURCE
#include <assert.h>
#include <errno.h>
#include <fcntl.h>
#include <linux/types.h>
#include <sched.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <syscall.h>
#include <sys/mount.h>
#include <sys/wait.h>

#include "kselftest_harness.h"
#include "../pidfd/pidfd.h"

#define __STACK_SIZE (8 * 1024 * 1024)
static pid_t do_clone(int (*fn)(void *), void *arg, int flags)
{
        char *stack;
        pid_t ret;

        stack = malloc(__STACK_SIZE);
        if (!stack)
                return -ENOMEM;

#ifdef __ia64__
        ret = __clone2(fn, stack, __STACK_SIZE, flags | SIGCHLD, arg);
#else
        ret = clone(fn, stack + __STACK_SIZE, flags | SIGCHLD, arg);
#endif
        free(stack);
        return ret;
}

static int pid_max_cb(void *data)
{
        int fd, ret;
        pid_t pid;

        ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
        if (ret) {
                fprintf(stderr, "%m - Failed to make rootfs private mount\n");
                return -1;
        }

        umount2("/proc", MNT_DETACH);

        ret = mount("proc", "/proc", "proc", 0, NULL);
        if (ret) {
                fprintf(stderr, "%m - Failed to mount proc\n");
                return -1;
        }

        fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY);
        if (fd < 0) {
                fprintf(stderr, "%m - Failed to open pid_max\n");
                return -1;
        }

        ret = write(fd, "500", sizeof("500") - 1);
        if (ret < 0) {
                fprintf(stderr, "%m - Failed to write pid_max\n");
                return -1;
        }

        for (int i = 0; i < 501; i++) {
                pid = fork();
                if (pid == 0)
                        exit(EXIT_SUCCESS);
                wait_for_pid(pid);
                if (pid > 500) {
                        fprintf(stderr, "Managed to create pid number beyond limit\n");
                        return -1;
                }
        }

        return 0;
}

static int pid_max_nested_inner(void *data)
{
        int fret = -1;
        pid_t pids[2];
        int fd, i, ret;

        ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
        if (ret) {
                fprintf(stderr, "%m - Failed to make rootfs private mount\n");
                return fret;
        }

        umount2("/proc", MNT_DETACH);

        ret = mount("proc", "/proc", "proc", 0, NULL);
        if (ret) {
                fprintf(stderr, "%m - Failed to mount proc\n");
                return fret;
        }

        fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY);
        if (fd < 0) {
                fprintf(stderr, "%m - Failed to open pid_max\n");
                return fret;
        }

        ret = write(fd, "500", sizeof("500") - 1);
        close(fd);
        if (ret < 0) {
                fprintf(stderr, "%m - Failed to write pid_max\n");
                return fret;
        }

        pids[0] = fork();
        if (pids[0] < 0) {
                fprintf(stderr, "Failed to create first new process\n");
                return fret;
        }

        if (pids[0] == 0)
                exit(EXIT_SUCCESS);

        pids[1] = fork();
        wait_for_pid(pids[0]);
        if (pids[1] >= 0) {
                if (pids[1] == 0)
                        exit(EXIT_SUCCESS);
                wait_for_pid(pids[1]);

                fprintf(stderr, "Managed to create process even though ancestor pid namespace had a limit\n");
                return fret;
        }

        /* Now make sure that we wrap pids at 400. */
        for (i = 0; i < 510; i++) {
                pid_t pid;

                pid = fork();
                if (pid < 0)
                        return fret;

                if (pid == 0)
                        exit(EXIT_SUCCESS);

                wait_for_pid(pid);
                if (pid >= 500) {
                        fprintf(stderr, "Managed to create process with pid %d beyond configured limit\n", pid);
                        return fret;
                }
        }

        return 0;
}

static int pid_max_nested_outer(void *data)
{
        int fret = -1, nr_procs = 400;
        pid_t pids[1000];
        int fd, i, ret;
        pid_t pid;

        ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
        if (ret) {
                fprintf(stderr, "%m - Failed to make rootfs private mount\n");
                return fret;
        }

        umount2("/proc", MNT_DETACH);

        ret = mount("proc", "/proc", "proc", 0, NULL);
        if (ret) {
                fprintf(stderr, "%m - Failed to mount proc\n");
                return fret;
        }

        fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY);
        if (fd < 0) {
                fprintf(stderr, "%m - Failed to open pid_max\n");
                return fret;
        }

        ret = write(fd, "400", sizeof("400") - 1);
        close(fd);
        if (ret < 0) {
                fprintf(stderr, "%m - Failed to write pid_max\n");
                return fret;
        }

        /*
         * Create 397 processes. This leaves room for do_clone() (398) and
         * one more 399. So creating another process needs to fail.
         */
        for (nr_procs = 0; nr_procs < 396; nr_procs++) {
                pid = fork();
                if (pid < 0)
                        goto reap;

                if (pid == 0)
                        exit(EXIT_SUCCESS);

                pids[nr_procs] = pid;
        }

        pid = do_clone(pid_max_nested_inner, NULL, CLONE_NEWPID | CLONE_NEWNS);
        if (pid < 0) {
                fprintf(stderr, "%m - Failed to clone nested pidns\n");
                goto reap;
        }

        if (wait_for_pid(pid)) {
                fprintf(stderr, "%m - Nested pid_max failed\n");
                goto reap;
        }

        fret = 0;

reap:
        for (int i = 0; i < nr_procs; i++)
                wait_for_pid(pids[i]);

        return fret;
}

static int pid_max_nested_limit_inner(void *data)
{
        int fret = -1, nr_procs = 400;
        int fd, ret;
        pid_t pid;
        pid_t pids[1000];

        ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
        if (ret) {
                fprintf(stderr, "%m - Failed to make rootfs private mount\n");
                return fret;
        }

        umount2("/proc", MNT_DETACH);

        ret = mount("proc", "/proc", "proc", 0, NULL);
        if (ret) {
                fprintf(stderr, "%m - Failed to mount proc\n");
                return fret;
        }

        fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY);
        if (fd < 0) {
                fprintf(stderr, "%m - Failed to open pid_max\n");
                return fret;
        }

        ret = write(fd, "500", sizeof("500") - 1);
        close(fd);
        if (ret < 0) {
                fprintf(stderr, "%m - Failed to write pid_max\n");
                return fret;
        }

        for (nr_procs = 0; nr_procs < 500; nr_procs++) {
                pid = fork();
                if (pid < 0)
                        break;

                if (pid == 0)
                        exit(EXIT_SUCCESS);

                pids[nr_procs] = pid;
        }

        if (nr_procs >= 400) {
                fprintf(stderr, "Managed to create processes beyond the configured outer limit\n");
                goto reap;
        }

        fret = 0;

reap:
        for (int i = 0; i < nr_procs; i++)
                wait_for_pid(pids[i]);

        return fret;
}

static int pid_max_nested_limit_outer(void *data)
{
        int fd, ret;
        pid_t pid;

        ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
        if (ret) {
                fprintf(stderr, "%m - Failed to make rootfs private mount\n");
                return -1;
        }

        umount2("/proc", MNT_DETACH);

        ret = mount("proc", "/proc", "proc", 0, NULL);
        if (ret) {
                fprintf(stderr, "%m - Failed to mount proc\n");
                return -1;
        }

        fd = open("/proc/sys/kernel/pid_max", O_RDWR | O_CLOEXEC | O_NOCTTY);
        if (fd < 0) {
                fprintf(stderr, "%m - Failed to open pid_max\n");
                return -1;
        }

        ret = write(fd, "400", sizeof("400") - 1);
        close(fd);
        if (ret < 0) {
                fprintf(stderr, "%m - Failed to write pid_max\n");
                return -1;
        }

        pid = do_clone(pid_max_nested_limit_inner, NULL, CLONE_NEWPID | CLONE_NEWNS);
        if (pid < 0) {
                fprintf(stderr, "%m - Failed to clone nested pidns\n");
                return -1;
        }

        if (wait_for_pid(pid)) {
                fprintf(stderr, "%m - Nested pid_max failed\n");
                return -1;
        }

        return 0;
}

TEST(pid_max_simple)
{
        pid_t pid;


        pid = do_clone(pid_max_cb, NULL, CLONE_NEWPID | CLONE_NEWNS);
        ASSERT_GT(pid, 0);
        ASSERT_EQ(0, wait_for_pid(pid));
}

TEST(pid_max_nested_limit)
{
        pid_t pid;

        pid = do_clone(pid_max_nested_limit_outer, NULL, CLONE_NEWPID | CLONE_NEWNS);
        ASSERT_GT(pid, 0);
        ASSERT_EQ(0, wait_for_pid(pid));
}

TEST(pid_max_nested)
{
        pid_t pid;

        pid = do_clone(pid_max_nested_outer, NULL, CLONE_NEWPID | CLONE_NEWNS);
        ASSERT_GT(pid, 0);
        ASSERT_EQ(0, wait_for_pid(pid));
}

TEST_HARNESS_MAIN