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