// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <grp.h>
#include <limits.h>
#include <sched.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <linux/unistd.h>
#include "kselftest_harness.h"

#ifndef FD_NSFS_ROOT
#define FD_NSFS_ROOT -10003 /* Root of the nsfs filesystem */
#endif

TEST(nsfs_net_handle)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        struct stat st1, st2;

        /* Drop to unprivileged uid/gid */
        ASSERT_EQ(setresgid(65534, 65534, 65534), 0); /* nogroup */
        ASSERT_EQ(setresuid(65534, 65534, 65534), 0); /* nobody */

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Open a namespace file descriptor */
        ns_fd = open("/proc/self/ns/net", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        /* Get handle for the namespace */
        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        ASSERT_GT(handle->handle_bytes, 0);

        /* Try to open using FD_NSFS_ROOT as unprivileged user */
        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
        if (fd < 0 && (errno == EINVAL || errno == EOPNOTSUPP)) {
                SKIP(free(handle); close(ns_fd);
                     return,
                           "open_by_handle_at with FD_NSFS_ROOT not supported");
        }
        if (fd < 0 && errno == EPERM) {
                SKIP(free(handle); close(ns_fd);
                     return,
                           "Permission denied for unprivileged user (expected)");
        }
        ASSERT_GE(fd, 0);

        /* Verify we opened the correct namespace */
        ASSERT_EQ(fstat(ns_fd, &st1), 0);
        ASSERT_EQ(fstat(fd, &st2), 0);
        ASSERT_EQ(st1.st_ino, st2.st_ino);
        ASSERT_EQ(st1.st_dev, st2.st_dev);

        close(fd);
        close(ns_fd);
        free(handle);
}

TEST(nsfs_uts_handle)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        struct stat st1, st2;

        /* Drop to unprivileged uid/gid */
        ASSERT_EQ(setresgid(65534, 65534, 65534), 0); /* nogroup */
        ASSERT_EQ(setresuid(65534, 65534, 65534), 0); /* nobody */

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Open UTS namespace file descriptor */
        ns_fd = open("/proc/self/ns/uts", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        /* Get handle for the namespace */
        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        ASSERT_GT(handle->handle_bytes, 0);

        /* Try to open using FD_NSFS_ROOT */
        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
        if (fd < 0 && (errno == EINVAL || errno == EOPNOTSUPP)) {
                SKIP(free(handle); close(ns_fd);
                     return,
                           "open_by_handle_at with FD_NSFS_ROOT not supported");
        }
        ASSERT_GE(fd, 0);

        /* Verify we opened the correct namespace */
        ASSERT_EQ(fstat(ns_fd, &st1), 0);
        ASSERT_EQ(fstat(fd, &st2), 0);
        ASSERT_EQ(st1.st_ino, st2.st_ino);
        ASSERT_EQ(st1.st_dev, st2.st_dev);

        close(fd);
        close(ns_fd);
        free(handle);
}

TEST(nsfs_ipc_handle)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        struct stat st1, st2;

        /* Drop to unprivileged uid/gid */
        ASSERT_EQ(setresgid(65534, 65534, 65534), 0); /* nogroup */
        ASSERT_EQ(setresuid(65534, 65534, 65534), 0); /* nobody */

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Open IPC namespace file descriptor */
        ns_fd = open("/proc/self/ns/ipc", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        /* Get handle for the namespace */
        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        ASSERT_GT(handle->handle_bytes, 0);

        /* Try to open using FD_NSFS_ROOT */
        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
        if (fd < 0 && (errno == EINVAL || errno == EOPNOTSUPP)) {
                SKIP(free(handle); close(ns_fd);
                     return,
                           "open_by_handle_at with FD_NSFS_ROOT not supported");
        }
        ASSERT_GE(fd, 0);

        /* Verify we opened the correct namespace */
        ASSERT_EQ(fstat(ns_fd, &st1), 0);
        ASSERT_EQ(fstat(fd, &st2), 0);
        ASSERT_EQ(st1.st_ino, st2.st_ino);
        ASSERT_EQ(st1.st_dev, st2.st_dev);

        close(fd);
        close(ns_fd);
        free(handle);
}

TEST(nsfs_pid_handle)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        struct stat st1, st2;

        /* Drop to unprivileged uid/gid */
        ASSERT_EQ(setresgid(65534, 65534, 65534), 0); /* nogroup */
        ASSERT_EQ(setresuid(65534, 65534, 65534), 0); /* nobody */

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Open PID namespace file descriptor */
        ns_fd = open("/proc/self/ns/pid", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        /* Get handle for the namespace */
        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        ASSERT_GT(handle->handle_bytes, 0);

        /* Try to open using FD_NSFS_ROOT */
        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
        if (fd < 0 && (errno == EINVAL || errno == EOPNOTSUPP)) {
                SKIP(free(handle); close(ns_fd);
                     return,
                           "open_by_handle_at with FD_NSFS_ROOT not supported");
        }
        ASSERT_GE(fd, 0);

        /* Verify we opened the correct namespace */
        ASSERT_EQ(fstat(ns_fd, &st1), 0);
        ASSERT_EQ(fstat(fd, &st2), 0);
        ASSERT_EQ(st1.st_ino, st2.st_ino);
        ASSERT_EQ(st1.st_dev, st2.st_dev);

        close(fd);
        close(ns_fd);
        free(handle);
}

TEST(nsfs_mnt_handle)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        struct stat st1, st2;

        /* Drop to unprivileged uid/gid */
        ASSERT_EQ(setresgid(65534, 65534, 65534), 0); /* nogroup */
        ASSERT_EQ(setresuid(65534, 65534, 65534), 0); /* nobody */

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Open mount namespace file descriptor */
        ns_fd = open("/proc/self/ns/mnt", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        /* Get handle for the namespace */
        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        ASSERT_GT(handle->handle_bytes, 0);

        /* Try to open using FD_NSFS_ROOT */
        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
        if (fd < 0 && (errno == EINVAL || errno == EOPNOTSUPP)) {
                SKIP(free(handle); close(ns_fd);
                     return,
                           "open_by_handle_at with FD_NSFS_ROOT not supported");
        }
        ASSERT_GE(fd, 0);

        /* Verify we opened the correct namespace */
        ASSERT_EQ(fstat(ns_fd, &st1), 0);
        ASSERT_EQ(fstat(fd, &st2), 0);
        ASSERT_EQ(st1.st_ino, st2.st_ino);
        ASSERT_EQ(st1.st_dev, st2.st_dev);

        close(fd);
        close(ns_fd);
        free(handle);
}

TEST(nsfs_user_handle)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        struct stat st1, st2;

        /* Drop to unprivileged uid/gid */
        ASSERT_EQ(setresgid(65534, 65534, 65534), 0); /* nogroup */
        ASSERT_EQ(setresuid(65534, 65534, 65534), 0); /* nobody */

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Open user namespace file descriptor */
        ns_fd = open("/proc/self/ns/user", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        /* Get handle for the namespace */
        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        ASSERT_GT(handle->handle_bytes, 0);

        /* Try to open using FD_NSFS_ROOT */
        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
        if (fd < 0 && (errno == EINVAL || errno == EOPNOTSUPP)) {
                SKIP(free(handle); close(ns_fd);
                     return,
                           "open_by_handle_at with FD_NSFS_ROOT not supported");
        }
        ASSERT_GE(fd, 0);

        /* Verify we opened the correct namespace */
        ASSERT_EQ(fstat(ns_fd, &st1), 0);
        ASSERT_EQ(fstat(fd, &st2), 0);
        ASSERT_EQ(st1.st_ino, st2.st_ino);
        ASSERT_EQ(st1.st_dev, st2.st_dev);

        close(fd);
        close(ns_fd);
        free(handle);
}

TEST(nsfs_cgroup_handle)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        struct stat st1, st2;

        /* Drop to unprivileged uid/gid */
        ASSERT_EQ(setresgid(65534, 65534, 65534), 0); /* nogroup */
        ASSERT_EQ(setresuid(65534, 65534, 65534), 0); /* nobody */

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Open cgroup namespace file descriptor */
        ns_fd = open("/proc/self/ns/cgroup", O_RDONLY);
        if (ns_fd < 0) {
                SKIP(free(handle); return, "cgroup namespace not available");
        }

        /* Get handle for the namespace */
        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        ASSERT_GT(handle->handle_bytes, 0);

        /* Try to open using FD_NSFS_ROOT */
        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
        if (fd < 0 && (errno == EINVAL || errno == EOPNOTSUPP)) {
                SKIP(free(handle); close(ns_fd);
                     return,
                           "open_by_handle_at with FD_NSFS_ROOT not supported");
        }
        ASSERT_GE(fd, 0);

        /* Verify we opened the correct namespace */
        ASSERT_EQ(fstat(ns_fd, &st1), 0);
        ASSERT_EQ(fstat(fd, &st2), 0);
        ASSERT_EQ(st1.st_ino, st2.st_ino);
        ASSERT_EQ(st1.st_dev, st2.st_dev);

        close(fd);
        close(ns_fd);
        free(handle);
}

TEST(nsfs_time_handle)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        struct stat st1, st2;

        /* Drop to unprivileged uid/gid */
        ASSERT_EQ(setresgid(65534, 65534, 65534), 0); /* nogroup */
        ASSERT_EQ(setresuid(65534, 65534, 65534), 0); /* nobody */

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Open time namespace file descriptor */
        ns_fd = open("/proc/self/ns/time", O_RDONLY);
        if (ns_fd < 0) {
                SKIP(free(handle); return, "time namespace not available");
        }

        /* Get handle for the namespace */
        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        ASSERT_GT(handle->handle_bytes, 0);

        /* Try to open using FD_NSFS_ROOT */
        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);
        if (fd < 0 && (errno == EINVAL || errno == EOPNOTSUPP)) {
                SKIP(free(handle); close(ns_fd);
                     return,
                           "open_by_handle_at with FD_NSFS_ROOT not supported");
        }
        ASSERT_GE(fd, 0);

        /* Verify we opened the correct namespace */
        ASSERT_EQ(fstat(ns_fd, &st1), 0);
        ASSERT_EQ(fstat(fd, &st2), 0);
        ASSERT_EQ(st1.st_ino, st2.st_ino);
        ASSERT_EQ(st1.st_dev, st2.st_dev);

        close(fd);
        close(ns_fd);
        free(handle);
}

TEST(nsfs_user_net_namespace_isolation)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        pid_t pid;
        int status;
        int pipefd[2];
        char result;

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Create pipe for communication */
        ASSERT_EQ(pipe(pipefd), 0);

        /* Get handle for current network namespace */
        ns_fd = open("/proc/self/ns/net", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd); close(pipefd[0]);
                     close(pipefd[1]);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        close(ns_fd);

        pid = fork();
        ASSERT_GE(pid, 0);

        if (pid == 0) {
                /* Child process */
                close(pipefd[0]);

                /* First create new user namespace to drop privileges */
                ret = unshare(CLONE_NEWUSER);
                if (ret < 0) {
                        write(pipefd[1], "U",
                              1); /* Unable to create user namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Write uid/gid mappings to maintain some capabilities */
                int uid_map_fd = open("/proc/self/uid_map", O_WRONLY);
                int gid_map_fd = open("/proc/self/gid_map", O_WRONLY);
                int setgroups_fd = open("/proc/self/setgroups", O_WRONLY);

                if (uid_map_fd < 0 || gid_map_fd < 0 || setgroups_fd < 0) {
                        write(pipefd[1], "M", 1); /* Unable to set mappings */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Disable setgroups to allow gid mapping */
                write(setgroups_fd, "deny", 4);
                close(setgroups_fd);

                /* Map current uid/gid to root in the new namespace */
                char mapping[64];
                snprintf(mapping, sizeof(mapping), "0 %d 1", getuid());
                write(uid_map_fd, mapping, strlen(mapping));
                close(uid_map_fd);

                snprintf(mapping, sizeof(mapping), "0 %d 1", getgid());
                write(gid_map_fd, mapping, strlen(mapping));
                close(gid_map_fd);

                /* Now create new network namespace */
                ret = unshare(CLONE_NEWNET);
                if (ret < 0) {
                        write(pipefd[1], "N",
                              1); /* Unable to create network namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Try to open parent's network namespace handle from new user+net namespace */
                fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);

                if (fd >= 0) {
                        /* Should NOT succeed - we're in a different user namespace */
                        write(pipefd[1], "S", 1); /* Unexpected success */
                        close(fd);
                } else if (errno == ESTALE) {
                        /* Expected: Stale file handle */
                        write(pipefd[1], "P", 1);
                } else {
                        /* Other error */
                        write(pipefd[1], "F", 1);
                }

                close(pipefd[1]);
                exit(0);
        }

        /* Parent process */
        close(pipefd[1]);
        ASSERT_EQ(read(pipefd[0], &result, 1), 1);

        waitpid(pid, &status, 0);
        ASSERT_TRUE(WIFEXITED(status));
        ASSERT_EQ(WEXITSTATUS(status), 0);

        if (result == 'U') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new user namespace");
        }
        if (result == 'M') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot set uid/gid mappings");
        }
        if (result == 'N') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new network namespace");
        }

        /* Should fail with permission denied since we're in a different user namespace */
        ASSERT_EQ(result, 'P');

        close(pipefd[0]);
        free(handle);
}

TEST(nsfs_user_uts_namespace_isolation)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        pid_t pid;
        int status;
        int pipefd[2];
        char result;

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Create pipe for communication */
        ASSERT_EQ(pipe(pipefd), 0);

        /* Get handle for current UTS namespace */
        ns_fd = open("/proc/self/ns/uts", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd); close(pipefd[0]);
                     close(pipefd[1]);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        close(ns_fd);

        pid = fork();
        ASSERT_GE(pid, 0);

        if (pid == 0) {
                /* Child process */
                close(pipefd[0]);

                /* First create new user namespace to drop privileges */
                ret = unshare(CLONE_NEWUSER);
                if (ret < 0) {
                        write(pipefd[1], "U",
                              1); /* Unable to create user namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Write uid/gid mappings to maintain some capabilities */
                int uid_map_fd = open("/proc/self/uid_map", O_WRONLY);
                int gid_map_fd = open("/proc/self/gid_map", O_WRONLY);
                int setgroups_fd = open("/proc/self/setgroups", O_WRONLY);

                if (uid_map_fd < 0 || gid_map_fd < 0 || setgroups_fd < 0) {
                        write(pipefd[1], "M", 1); /* Unable to set mappings */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Disable setgroups to allow gid mapping */
                write(setgroups_fd, "deny", 4);
                close(setgroups_fd);

                /* Map current uid/gid to root in the new namespace */
                char mapping[64];
                snprintf(mapping, sizeof(mapping), "0 %d 1", getuid());
                write(uid_map_fd, mapping, strlen(mapping));
                close(uid_map_fd);

                snprintf(mapping, sizeof(mapping), "0 %d 1", getgid());
                write(gid_map_fd, mapping, strlen(mapping));
                close(gid_map_fd);

                /* Now create new UTS namespace */
                ret = unshare(CLONE_NEWUTS);
                if (ret < 0) {
                        write(pipefd[1], "N",
                              1); /* Unable to create UTS namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Try to open parent's UTS namespace handle from new user+uts namespace */
                fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);

                if (fd >= 0) {
                        /* Should NOT succeed - we're in a different user namespace */
                        write(pipefd[1], "S", 1); /* Unexpected success */
                        close(fd);
                } else if (errno == ESTALE) {
                        /* Expected: Stale file handle */
                        write(pipefd[1], "P", 1);
                } else {
                        /* Other error */
                        write(pipefd[1], "F", 1);
                }

                close(pipefd[1]);
                exit(0);
        }

        /* Parent process */
        close(pipefd[1]);
        ASSERT_EQ(read(pipefd[0], &result, 1), 1);

        waitpid(pid, &status, 0);
        ASSERT_TRUE(WIFEXITED(status));
        ASSERT_EQ(WEXITSTATUS(status), 0);

        if (result == 'U') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new user namespace");
        }
        if (result == 'M') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot set uid/gid mappings");
        }
        if (result == 'N') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new UTS namespace");
        }

        /* Should fail with ESTALE since we're in a different user namespace */
        ASSERT_EQ(result, 'P');

        close(pipefd[0]);
        free(handle);
}

TEST(nsfs_user_ipc_namespace_isolation)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        pid_t pid;
        int status;
        int pipefd[2];
        char result;

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Create pipe for communication */
        ASSERT_EQ(pipe(pipefd), 0);

        /* Get handle for current IPC namespace */
        ns_fd = open("/proc/self/ns/ipc", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd); close(pipefd[0]);
                     close(pipefd[1]);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        close(ns_fd);

        pid = fork();
        ASSERT_GE(pid, 0);

        if (pid == 0) {
                /* Child process */
                close(pipefd[0]);

                /* First create new user namespace to drop privileges */
                ret = unshare(CLONE_NEWUSER);
                if (ret < 0) {
                        write(pipefd[1], "U",
                              1); /* Unable to create user namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Write uid/gid mappings to maintain some capabilities */
                int uid_map_fd = open("/proc/self/uid_map", O_WRONLY);
                int gid_map_fd = open("/proc/self/gid_map", O_WRONLY);
                int setgroups_fd = open("/proc/self/setgroups", O_WRONLY);

                if (uid_map_fd < 0 || gid_map_fd < 0 || setgroups_fd < 0) {
                        write(pipefd[1], "M", 1); /* Unable to set mappings */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Disable setgroups to allow gid mapping */
                write(setgroups_fd, "deny", 4);
                close(setgroups_fd);

                /* Map current uid/gid to root in the new namespace */
                char mapping[64];
                snprintf(mapping, sizeof(mapping), "0 %d 1", getuid());
                write(uid_map_fd, mapping, strlen(mapping));
                close(uid_map_fd);

                snprintf(mapping, sizeof(mapping), "0 %d 1", getgid());
                write(gid_map_fd, mapping, strlen(mapping));
                close(gid_map_fd);

                /* Now create new IPC namespace */
                ret = unshare(CLONE_NEWIPC);
                if (ret < 0) {
                        write(pipefd[1], "N",
                              1); /* Unable to create IPC namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Try to open parent's IPC namespace handle from new user+ipc namespace */
                fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);

                if (fd >= 0) {
                        /* Should NOT succeed - we're in a different user namespace */
                        write(pipefd[1], "S", 1); /* Unexpected success */
                        close(fd);
                } else if (errno == ESTALE) {
                        /* Expected: Stale file handle */
                        write(pipefd[1], "P", 1);
                } else {
                        /* Other error */
                        write(pipefd[1], "F", 1);
                }

                close(pipefd[1]);
                exit(0);
        }

        /* Parent process */
        close(pipefd[1]);
        ASSERT_EQ(read(pipefd[0], &result, 1), 1);

        waitpid(pid, &status, 0);
        ASSERT_TRUE(WIFEXITED(status));
        ASSERT_EQ(WEXITSTATUS(status), 0);

        if (result == 'U') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new user namespace");
        }
        if (result == 'M') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot set uid/gid mappings");
        }
        if (result == 'N') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new IPC namespace");
        }

        /* Should fail with ESTALE since we're in a different user namespace */
        ASSERT_EQ(result, 'P');

        close(pipefd[0]);
        free(handle);
}

TEST(nsfs_user_mnt_namespace_isolation)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        pid_t pid;
        int status;
        int pipefd[2];
        char result;

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Create pipe for communication */
        ASSERT_EQ(pipe(pipefd), 0);

        /* Get handle for current mount namespace */
        ns_fd = open("/proc/self/ns/mnt", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd); close(pipefd[0]);
                     close(pipefd[1]);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        close(ns_fd);

        pid = fork();
        ASSERT_GE(pid, 0);

        if (pid == 0) {
                /* Child process */
                close(pipefd[0]);

                /* First create new user namespace to drop privileges */
                ret = unshare(CLONE_NEWUSER);
                if (ret < 0) {
                        write(pipefd[1], "U",
                              1); /* Unable to create user namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Write uid/gid mappings to maintain some capabilities */
                int uid_map_fd = open("/proc/self/uid_map", O_WRONLY);
                int gid_map_fd = open("/proc/self/gid_map", O_WRONLY);
                int setgroups_fd = open("/proc/self/setgroups", O_WRONLY);

                if (uid_map_fd < 0 || gid_map_fd < 0 || setgroups_fd < 0) {
                        write(pipefd[1], "M", 1); /* Unable to set mappings */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Disable setgroups to allow gid mapping */
                write(setgroups_fd, "deny", 4);
                close(setgroups_fd);

                /* Map current uid/gid to root in the new namespace */
                char mapping[64];
                snprintf(mapping, sizeof(mapping), "0 %d 1", getuid());
                write(uid_map_fd, mapping, strlen(mapping));
                close(uid_map_fd);

                snprintf(mapping, sizeof(mapping), "0 %d 1", getgid());
                write(gid_map_fd, mapping, strlen(mapping));
                close(gid_map_fd);

                /* Now create new mount namespace */
                ret = unshare(CLONE_NEWNS);
                if (ret < 0) {
                        write(pipefd[1], "N",
                              1); /* Unable to create mount namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Try to open parent's mount namespace handle from new user+mnt namespace */
                fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);

                if (fd >= 0) {
                        /* Should NOT succeed - we're in a different user namespace */
                        write(pipefd[1], "S", 1); /* Unexpected success */
                        close(fd);
                } else if (errno == ESTALE) {
                        /* Expected: Stale file handle */
                        write(pipefd[1], "P", 1);
                } else {
                        /* Other error */
                        write(pipefd[1], "F", 1);
                }

                close(pipefd[1]);
                exit(0);
        }

        /* Parent process */
        close(pipefd[1]);
        ASSERT_EQ(read(pipefd[0], &result, 1), 1);

        waitpid(pid, &status, 0);
        ASSERT_TRUE(WIFEXITED(status));
        ASSERT_EQ(WEXITSTATUS(status), 0);

        if (result == 'U') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new user namespace");
        }
        if (result == 'M') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot set uid/gid mappings");
        }
        if (result == 'N') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new mount namespace");
        }

        /* Should fail with ESTALE since we're in a different user namespace */
        ASSERT_EQ(result, 'P');

        close(pipefd[0]);
        free(handle);
}

TEST(nsfs_user_cgroup_namespace_isolation)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        pid_t pid;
        int status;
        int pipefd[2];
        char result;

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Create pipe for communication */
        ASSERT_EQ(pipe(pipefd), 0);

        /* Get handle for current cgroup namespace */
        ns_fd = open("/proc/self/ns/cgroup", O_RDONLY);
        if (ns_fd < 0) {
                SKIP(free(handle); close(pipefd[0]); close(pipefd[1]);
                     return, "cgroup namespace not available");
        }

        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd); close(pipefd[0]);
                     close(pipefd[1]);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        close(ns_fd);

        pid = fork();
        ASSERT_GE(pid, 0);

        if (pid == 0) {
                /* Child process */
                close(pipefd[0]);

                /* First create new user namespace to drop privileges */
                ret = unshare(CLONE_NEWUSER);
                if (ret < 0) {
                        write(pipefd[1], "U",
                              1); /* Unable to create user namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Write uid/gid mappings to maintain some capabilities */
                int uid_map_fd = open("/proc/self/uid_map", O_WRONLY);
                int gid_map_fd = open("/proc/self/gid_map", O_WRONLY);
                int setgroups_fd = open("/proc/self/setgroups", O_WRONLY);

                if (uid_map_fd < 0 || gid_map_fd < 0 || setgroups_fd < 0) {
                        write(pipefd[1], "M", 1); /* Unable to set mappings */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Disable setgroups to allow gid mapping */
                write(setgroups_fd, "deny", 4);
                close(setgroups_fd);

                /* Map current uid/gid to root in the new namespace */
                char mapping[64];
                snprintf(mapping, sizeof(mapping), "0 %d 1", getuid());
                write(uid_map_fd, mapping, strlen(mapping));
                close(uid_map_fd);

                snprintf(mapping, sizeof(mapping), "0 %d 1", getgid());
                write(gid_map_fd, mapping, strlen(mapping));
                close(gid_map_fd);

                /* Now create new cgroup namespace */
                ret = unshare(CLONE_NEWCGROUP);
                if (ret < 0) {
                        write(pipefd[1], "N",
                              1); /* Unable to create cgroup namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Try to open parent's cgroup namespace handle from new user+cgroup namespace */
                fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);

                if (fd >= 0) {
                        /* Should NOT succeed - we're in a different user namespace */
                        write(pipefd[1], "S", 1); /* Unexpected success */
                        close(fd);
                } else if (errno == ESTALE) {
                        /* Expected: Stale file handle */
                        write(pipefd[1], "P", 1);
                } else {
                        /* Other error */
                        write(pipefd[1], "F", 1);
                }

                close(pipefd[1]);
                exit(0);
        }

        /* Parent process */
        close(pipefd[1]);
        ASSERT_EQ(read(pipefd[0], &result, 1), 1);

        waitpid(pid, &status, 0);
        ASSERT_TRUE(WIFEXITED(status));
        ASSERT_EQ(WEXITSTATUS(status), 0);

        if (result == 'U') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new user namespace");
        }
        if (result == 'M') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot set uid/gid mappings");
        }
        if (result == 'N') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new cgroup namespace");
        }

        /* Should fail with ESTALE since we're in a different user namespace */
        ASSERT_EQ(result, 'P');

        close(pipefd[0]);
        free(handle);
}

TEST(nsfs_user_pid_namespace_isolation)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        pid_t pid;
        int status;
        int pipefd[2];
        char result;

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Create pipe for communication */
        ASSERT_EQ(pipe(pipefd), 0);

        /* Get handle for current PID namespace */
        ns_fd = open("/proc/self/ns/pid", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd); close(pipefd[0]);
                     close(pipefd[1]);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        close(ns_fd);

        pid = fork();
        ASSERT_GE(pid, 0);

        if (pid == 0) {
                /* Child process */
                close(pipefd[0]);

                /* First create new user namespace to drop privileges */
                ret = unshare(CLONE_NEWUSER);
                if (ret < 0) {
                        write(pipefd[1], "U",
                              1); /* Unable to create user namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Write uid/gid mappings to maintain some capabilities */
                int uid_map_fd = open("/proc/self/uid_map", O_WRONLY);
                int gid_map_fd = open("/proc/self/gid_map", O_WRONLY);
                int setgroups_fd = open("/proc/self/setgroups", O_WRONLY);

                if (uid_map_fd < 0 || gid_map_fd < 0 || setgroups_fd < 0) {
                        write(pipefd[1], "M", 1); /* Unable to set mappings */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Disable setgroups to allow gid mapping */
                write(setgroups_fd, "deny", 4);
                close(setgroups_fd);

                /* Map current uid/gid to root in the new namespace */
                char mapping[64];
                snprintf(mapping, sizeof(mapping), "0 %d 1", getuid());
                write(uid_map_fd, mapping, strlen(mapping));
                close(uid_map_fd);

                snprintf(mapping, sizeof(mapping), "0 %d 1", getgid());
                write(gid_map_fd, mapping, strlen(mapping));
                close(gid_map_fd);

                /* Now create new PID namespace - requires fork to take effect */
                ret = unshare(CLONE_NEWPID);
                if (ret < 0) {
                        write(pipefd[1], "N",
                              1); /* Unable to create PID namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Fork again for PID namespace to take effect */
                pid_t child_pid = fork();
                if (child_pid < 0) {
                        write(pipefd[1], "N",
                              1); /* Unable to fork in PID namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                if (child_pid == 0) {
                        /* Grandchild in new PID namespace */
                        /* Try to open parent's PID namespace handle from new user+pid namespace */
                        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);

                        if (fd >= 0) {
                                /* Should NOT succeed - we're in a different user namespace */
                                write(pipefd[1], "S",
                                      1); /* Unexpected success */
                                close(fd);
                        } else if (errno == ESTALE) {
                                /* Expected: Stale file handle */
                                write(pipefd[1], "P", 1);
                        } else {
                                /* Other error */
                                write(pipefd[1], "F", 1);
                        }

                        close(pipefd[1]);
                        exit(0);
                }

                /* Wait for grandchild */
                waitpid(child_pid, NULL, 0);
                exit(0);
        }

        /* Parent process */
        close(pipefd[1]);
        ASSERT_EQ(read(pipefd[0], &result, 1), 1);

        waitpid(pid, &status, 0);
        ASSERT_TRUE(WIFEXITED(status));
        ASSERT_EQ(WEXITSTATUS(status), 0);

        if (result == 'U') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new user namespace");
        }
        if (result == 'M') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot set uid/gid mappings");
        }
        if (result == 'N') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new PID namespace");
        }

        /* Should fail with ESTALE since we're in a different user namespace */
        ASSERT_EQ(result, 'P');

        close(pipefd[0]);
        free(handle);
}

TEST(nsfs_user_time_namespace_isolation)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;
        pid_t pid;
        int status;
        int pipefd[2];
        char result;

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Create pipe for communication */
        ASSERT_EQ(pipe(pipefd), 0);

        /* Get handle for current time namespace */
        ns_fd = open("/proc/self/ns/time", O_RDONLY);
        if (ns_fd < 0) {
                SKIP(free(handle); close(pipefd[0]); close(pipefd[1]);
                     return, "time namespace not available");
        }

        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd); close(pipefd[0]);
                     close(pipefd[1]);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        close(ns_fd);

        pid = fork();
        ASSERT_GE(pid, 0);

        if (pid == 0) {
                /* Child process */
                close(pipefd[0]);

                /* First create new user namespace to drop privileges */
                ret = unshare(CLONE_NEWUSER);
                if (ret < 0) {
                        write(pipefd[1], "U",
                              1); /* Unable to create user namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Write uid/gid mappings to maintain some capabilities */
                int uid_map_fd = open("/proc/self/uid_map", O_WRONLY);
                int gid_map_fd = open("/proc/self/gid_map", O_WRONLY);
                int setgroups_fd = open("/proc/self/setgroups", O_WRONLY);

                if (uid_map_fd < 0 || gid_map_fd < 0 || setgroups_fd < 0) {
                        write(pipefd[1], "M", 1); /* Unable to set mappings */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Disable setgroups to allow gid mapping */
                write(setgroups_fd, "deny", 4);
                close(setgroups_fd);

                /* Map current uid/gid to root in the new namespace */
                char mapping[64];
                snprintf(mapping, sizeof(mapping), "0 %d 1", getuid());
                write(uid_map_fd, mapping, strlen(mapping));
                close(uid_map_fd);

                snprintf(mapping, sizeof(mapping), "0 %d 1", getgid());
                write(gid_map_fd, mapping, strlen(mapping));
                close(gid_map_fd);

                /* Now create new time namespace - requires fork to take effect */
                ret = unshare(CLONE_NEWTIME);
                if (ret < 0) {
                        write(pipefd[1], "N",
                              1); /* Unable to create time namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                /* Fork again for time namespace to take effect */
                pid_t child_pid = fork();
                if (child_pid < 0) {
                        write(pipefd[1], "N",
                              1); /* Unable to fork in time namespace */
                        close(pipefd[1]);
                        exit(0);
                }

                if (child_pid == 0) {
                        /* Grandchild in new time namespace */
                        /* Try to open parent's time namespace handle from new user+time namespace */
                        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDONLY);

                        if (fd >= 0) {
                                /* Should NOT succeed - we're in a different user namespace */
                                write(pipefd[1], "S",
                                      1); /* Unexpected success */
                                close(fd);
                        } else if (errno == ESTALE) {
                                /* Expected: Stale file handle */
                                write(pipefd[1], "P", 1);
                        } else {
                                /* Other error */
                                write(pipefd[1], "F", 1);
                        }

                        close(pipefd[1]);
                        exit(0);
                }

                /* Wait for grandchild */
                waitpid(child_pid, NULL, 0);
                exit(0);
        }

        /* Parent process */
        close(pipefd[1]);
        ASSERT_EQ(read(pipefd[0], &result, 1), 1);

        waitpid(pid, &status, 0);
        ASSERT_TRUE(WIFEXITED(status));
        ASSERT_EQ(WEXITSTATUS(status), 0);

        if (result == 'U') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new user namespace");
        }
        if (result == 'M') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot set uid/gid mappings");
        }
        if (result == 'N') {
                SKIP(free(handle); close(pipefd[0]);
                     return, "Cannot create new time namespace");
        }

        /* Should fail with ESTALE since we're in a different user namespace */
        ASSERT_EQ(result, 'P');

        close(pipefd[0]);
        free(handle);
}

TEST(nsfs_open_flags)
{
        struct file_handle *handle;
        int mount_id;
        int ret;
        int fd;
        int ns_fd;

        handle = malloc(sizeof(*handle) + MAX_HANDLE_SZ);
        ASSERT_NE(handle, NULL);

        /* Open a namespace file descriptor */
        ns_fd = open("/proc/self/ns/net", O_RDONLY);
        ASSERT_GE(ns_fd, 0);

        /* Get handle for the namespace */
        handle->handle_bytes = MAX_HANDLE_SZ;
        ret = name_to_handle_at(ns_fd, "", handle, &mount_id, AT_EMPTY_PATH);
        if (ret < 0 && errno == EOPNOTSUPP) {
                SKIP(free(handle); close(ns_fd);
                     return, "nsfs doesn't support file handles");
        }
        ASSERT_EQ(ret, 0);
        ASSERT_GT(handle->handle_bytes, 0);

        /* Test invalid flags that should fail */
        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_WRONLY);
        ASSERT_LT(fd, 0);
        ASSERT_EQ(errno, EPERM);

        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_RDWR);
        ASSERT_LT(fd, 0);
        ASSERT_EQ(errno, EPERM);

        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_TRUNC);
        ASSERT_LT(fd, 0);
        ASSERT_EQ(errno, EPERM);

        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_DIRECT);
        ASSERT_LT(fd, 0);
        ASSERT_EQ(errno, EINVAL);

        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_TMPFILE);
        ASSERT_LT(fd, 0);
        ASSERT_EQ(errno, EINVAL);

        fd = open_by_handle_at(FD_NSFS_ROOT, handle, O_DIRECTORY);
        ASSERT_LT(fd, 0);
        ASSERT_EQ(errno, ENOTDIR);

        close(ns_fd);
        free(handle);
}

TEST_HARNESS_MAIN