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317 lines
5.9 KiB
317 lines
5.9 KiB
// SPDX-License-Identifier: GPL-2.0
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#define _GNU_SOURCE
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#include <errno.h>
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#include <fcntl.h>
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#include <sched.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <asm/ioctls.h>
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#include <sys/mount.h>
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#include <sys/wait.h>
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#include "../kselftest.h"
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static bool terminal_dup2(int duplicate, int original)
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{
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int ret;
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ret = dup2(duplicate, original);
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if (ret < 0)
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return false;
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return true;
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}
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static int terminal_set_stdfds(int fd)
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{
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int i;
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if (fd < 0)
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return 0;
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for (i = 0; i < 3; i++)
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if (!terminal_dup2(fd, (int[]){STDIN_FILENO, STDOUT_FILENO,
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STDERR_FILENO}[i]))
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return -1;
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return 0;
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}
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static int login_pty(int fd)
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{
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int ret;
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setsid();
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ret = ioctl(fd, TIOCSCTTY, NULL);
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if (ret < 0)
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return -1;
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ret = terminal_set_stdfds(fd);
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if (ret < 0)
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return -1;
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if (fd > STDERR_FILENO)
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close(fd);
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return 0;
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}
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static int wait_for_pid(pid_t pid)
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{
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int status, ret;
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again:
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ret = waitpid(pid, &status, 0);
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if (ret == -1) {
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if (errno == EINTR)
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goto again;
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return -1;
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}
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if (ret != pid)
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goto again;
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if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
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return -1;
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return 0;
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}
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static int resolve_procfd_symlink(int fd, char *buf, size_t buflen)
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{
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int ret;
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char procfd[4096];
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ret = snprintf(procfd, 4096, "/proc/self/fd/%d", fd);
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if (ret < 0 || ret >= 4096)
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return -1;
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ret = readlink(procfd, buf, buflen);
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if (ret < 0 || (size_t)ret >= buflen)
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return -1;
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buf[ret] = '\0';
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return 0;
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}
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static int do_tiocgptpeer(char *ptmx, char *expected_procfd_contents)
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{
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int ret;
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int master = -1, slave = -1, fret = -1;
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master = open(ptmx, O_RDWR | O_NOCTTY | O_CLOEXEC);
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if (master < 0) {
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fprintf(stderr, "Failed to open \"%s\": %s\n", ptmx,
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strerror(errno));
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return -1;
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}
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/*
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* grantpt() makes assumptions about /dev/pts/ so ignore it. It's also
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* not really needed.
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*/
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ret = unlockpt(master);
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if (ret < 0) {
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fprintf(stderr, "Failed to unlock terminal\n");
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goto do_cleanup;
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}
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#ifdef TIOCGPTPEER
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slave = ioctl(master, TIOCGPTPEER, O_RDWR | O_NOCTTY | O_CLOEXEC);
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#endif
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if (slave < 0) {
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if (errno == EINVAL) {
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fprintf(stderr, "TIOCGPTPEER is not supported. "
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"Skipping test.\n");
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fret = KSFT_SKIP;
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} else {
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fprintf(stderr,
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"Failed to perform TIOCGPTPEER ioctl\n");
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fret = EXIT_FAILURE;
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}
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goto do_cleanup;
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}
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pid_t pid = fork();
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if (pid < 0)
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goto do_cleanup;
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if (pid == 0) {
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char buf[4096];
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ret = login_pty(slave);
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if (ret < 0) {
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fprintf(stderr, "Failed to setup terminal\n");
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_exit(EXIT_FAILURE);
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}
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ret = resolve_procfd_symlink(STDIN_FILENO, buf, sizeof(buf));
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if (ret < 0) {
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fprintf(stderr, "Failed to retrieve pathname of pts "
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"slave file descriptor\n");
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_exit(EXIT_FAILURE);
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}
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if (strncmp(expected_procfd_contents, buf,
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strlen(expected_procfd_contents)) != 0) {
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fprintf(stderr, "Received invalid contents for "
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"\"/proc/<pid>/fd/%d\" symlink: %s\n",
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STDIN_FILENO, buf);
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_exit(-1);
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}
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fprintf(stderr, "Contents of \"/proc/<pid>/fd/%d\" "
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"symlink are valid: %s\n", STDIN_FILENO, buf);
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_exit(EXIT_SUCCESS);
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}
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ret = wait_for_pid(pid);
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if (ret < 0)
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goto do_cleanup;
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fret = EXIT_SUCCESS;
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do_cleanup:
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if (master >= 0)
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close(master);
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if (slave >= 0)
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close(slave);
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return fret;
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}
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static int verify_non_standard_devpts_mount(void)
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{
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char *mntpoint;
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int ret = -1;
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char devpts[] = P_tmpdir "/devpts_fs_XXXXXX";
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char ptmx[] = P_tmpdir "/devpts_fs_XXXXXX/ptmx";
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ret = umount("/dev/pts");
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if (ret < 0) {
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fprintf(stderr, "Failed to unmount \"/dev/pts\": %s\n",
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strerror(errno));
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return -1;
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}
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(void)umount("/dev/ptmx");
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mntpoint = mkdtemp(devpts);
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if (!mntpoint) {
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fprintf(stderr, "Failed to create temporary mountpoint: %s\n",
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strerror(errno));
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return -1;
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}
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ret = mount("devpts", mntpoint, "devpts", MS_NOSUID | MS_NOEXEC,
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"newinstance,ptmxmode=0666,mode=0620,gid=5");
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if (ret < 0) {
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fprintf(stderr, "Failed to mount devpts fs to \"%s\" in new "
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"mount namespace: %s\n", mntpoint,
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strerror(errno));
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unlink(mntpoint);
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return -1;
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}
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ret = snprintf(ptmx, sizeof(ptmx), "%s/ptmx", devpts);
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if (ret < 0 || (size_t)ret >= sizeof(ptmx)) {
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unlink(mntpoint);
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return -1;
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}
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ret = do_tiocgptpeer(ptmx, mntpoint);
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unlink(mntpoint);
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if (ret < 0)
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return -1;
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return 0;
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}
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static int verify_ptmx_bind_mount(void)
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{
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int ret;
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ret = mount("/dev/pts/ptmx", "/dev/ptmx", NULL, MS_BIND, NULL);
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if (ret < 0) {
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fprintf(stderr, "Failed to bind mount \"/dev/pts/ptmx\" to "
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"\"/dev/ptmx\" mount namespace\n");
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return -1;
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}
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ret = do_tiocgptpeer("/dev/ptmx", "/dev/pts/");
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if (ret < 0)
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return -1;
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return 0;
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}
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static int verify_invalid_ptmx_bind_mount(void)
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{
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int ret;
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char mntpoint_fd;
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char ptmx[] = P_tmpdir "/devpts_ptmx_XXXXXX";
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mntpoint_fd = mkstemp(ptmx);
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if (mntpoint_fd < 0) {
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fprintf(stderr, "Failed to create temporary directory: %s\n",
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strerror(errno));
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return -1;
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}
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ret = mount("/dev/pts/ptmx", ptmx, NULL, MS_BIND, NULL);
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close(mntpoint_fd);
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if (ret < 0) {
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fprintf(stderr, "Failed to bind mount \"/dev/pts/ptmx\" to "
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"\"%s\" mount namespace\n", ptmx);
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return -1;
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}
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ret = do_tiocgptpeer(ptmx, "/dev/pts/");
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if (ret == 0)
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return -1;
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return 0;
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}
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int main(int argc, char *argv[])
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{
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int ret;
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if (!isatty(STDIN_FILENO)) {
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fprintf(stderr, "Standard input file descriptor is not attached "
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"to a terminal. Skipping test\n");
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exit(KSFT_SKIP);
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}
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ret = unshare(CLONE_NEWNS);
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if (ret < 0) {
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fprintf(stderr, "Failed to unshare mount namespace\n");
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exit(EXIT_FAILURE);
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}
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ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
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if (ret < 0) {
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fprintf(stderr, "Failed to make \"/\" MS_PRIVATE in new mount "
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"namespace\n");
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exit(EXIT_FAILURE);
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}
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ret = verify_ptmx_bind_mount();
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if (ret < 0)
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exit(EXIT_FAILURE);
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ret = verify_invalid_ptmx_bind_mount();
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if (ret < 0)
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exit(EXIT_FAILURE);
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ret = verify_non_standard_devpts_mount();
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if (ret < 0)
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exit(EXIT_FAILURE);
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exit(EXIT_SUCCESS);
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}
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