1 // SPDX-License-Identifier: GPL-2.0
11 #include <asm/ioctls.h>
12 #include <sys/mount.h>
14 #include "../kselftest.h"
16 static bool terminal_dup2(int duplicate, int original)
20 ret = dup2(duplicate, original);
27 static int terminal_set_stdfds(int fd)
34 for (i = 0; i < 3; i++)
35 if (!terminal_dup2(fd, (int[]){STDIN_FILENO, STDOUT_FILENO,
42 static int login_pty(int fd)
48 ret = ioctl(fd, TIOCSCTTY, NULL);
52 ret = terminal_set_stdfds(fd);
56 if (fd > STDERR_FILENO)
62 static int wait_for_pid(pid_t pid)
67 ret = waitpid(pid, &status, 0);
76 if (!WIFEXITED(status) || WEXITSTATUS(status) != 0)
82 static int resolve_procfd_symlink(int fd, char *buf, size_t buflen)
87 ret = snprintf(procfd, 4096, "/proc/self/fd/%d", fd);
88 if (ret < 0 || ret >= 4096)
91 ret = readlink(procfd, buf, buflen);
92 if (ret < 0 || (size_t)ret >= buflen)
100 static int do_tiocgptpeer(char *ptmx, char *expected_procfd_contents)
103 int master = -1, slave = -1, fret = -1;
105 master = open(ptmx, O_RDWR | O_NOCTTY | O_CLOEXEC);
107 fprintf(stderr, "Failed to open \"%s\": %s\n", ptmx,
113 * grantpt() makes assumptions about /dev/pts/ so ignore it. It's also
116 ret = unlockpt(master);
118 fprintf(stderr, "Failed to unlock terminal\n");
123 slave = ioctl(master, TIOCGPTPEER, O_RDWR | O_NOCTTY | O_CLOEXEC);
126 if (errno == EINVAL) {
127 fprintf(stderr, "TIOCGPTPEER is not supported. "
132 "Failed to perform TIOCGPTPEER ioctl\n");
145 ret = login_pty(slave);
147 fprintf(stderr, "Failed to setup terminal\n");
151 ret = resolve_procfd_symlink(STDIN_FILENO, buf, sizeof(buf));
153 fprintf(stderr, "Failed to retrieve pathname of pts "
154 "slave file descriptor\n");
158 if (strncmp(expected_procfd_contents, buf,
159 strlen(expected_procfd_contents)) != 0) {
160 fprintf(stderr, "Received invalid contents for "
161 "\"/proc/<pid>/fd/%d\" symlink: %s\n",
166 fprintf(stderr, "Contents of \"/proc/<pid>/fd/%d\" "
167 "symlink are valid: %s\n", STDIN_FILENO, buf);
172 ret = wait_for_pid(pid);
187 static int verify_non_standard_devpts_mount(void)
191 char devpts[] = P_tmpdir "/devpts_fs_XXXXXX";
192 char ptmx[] = P_tmpdir "/devpts_fs_XXXXXX/ptmx";
194 ret = umount("/dev/pts");
196 fprintf(stderr, "Failed to unmount \"/dev/pts\": %s\n",
201 (void)umount("/dev/ptmx");
203 mntpoint = mkdtemp(devpts);
205 fprintf(stderr, "Failed to create temporary mountpoint: %s\n",
210 ret = mount("devpts", mntpoint, "devpts", MS_NOSUID | MS_NOEXEC,
211 "newinstance,ptmxmode=0666,mode=0620,gid=5");
213 fprintf(stderr, "Failed to mount devpts fs to \"%s\" in new "
214 "mount namespace: %s\n", mntpoint,
220 ret = snprintf(ptmx, sizeof(ptmx), "%s/ptmx", devpts);
221 if (ret < 0 || (size_t)ret >= sizeof(ptmx)) {
226 ret = do_tiocgptpeer(ptmx, mntpoint);
234 static int verify_ptmx_bind_mount(void)
238 ret = mount("/dev/pts/ptmx", "/dev/ptmx", NULL, MS_BIND, NULL);
240 fprintf(stderr, "Failed to bind mount \"/dev/pts/ptmx\" to "
241 "\"/dev/ptmx\" mount namespace\n");
245 ret = do_tiocgptpeer("/dev/ptmx", "/dev/pts/");
252 static int verify_invalid_ptmx_bind_mount(void)
256 char ptmx[] = P_tmpdir "/devpts_ptmx_XXXXXX";
258 mntpoint_fd = mkstemp(ptmx);
259 if (mntpoint_fd < 0) {
260 fprintf(stderr, "Failed to create temporary directory: %s\n",
265 ret = mount("/dev/pts/ptmx", ptmx, NULL, MS_BIND, NULL);
268 fprintf(stderr, "Failed to bind mount \"/dev/pts/ptmx\" to "
269 "\"%s\" mount namespace\n", ptmx);
273 ret = do_tiocgptpeer(ptmx, "/dev/pts/");
280 int main(int argc, char *argv[])
284 if (!isatty(STDIN_FILENO)) {
285 fprintf(stderr, "Standard input file descriptor is not attached "
286 "to a terminal. Skipping test\n");
290 ret = unshare(CLONE_NEWNS);
292 fprintf(stderr, "Failed to unshare mount namespace\n");
296 ret = mount("", "/", NULL, MS_PRIVATE | MS_REC, 0);
298 fprintf(stderr, "Failed to make \"/\" MS_PRIVATE in new mount "
303 ret = verify_ptmx_bind_mount();
307 ret = verify_invalid_ptmx_bind_mount();
311 ret = verify_non_standard_devpts_mount();