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#define _GNU_SOURCE
#include <sched.h>
#include <stdio.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/mount.h>
#include <sys/wait.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <grp.h>
#include <stdbool.h>
#include <stdarg.h>
#ifndef CLONE_NEWNS
# define CLONE_NEWNS 0x00020000
#endif
#ifndef CLONE_NEWUTS
# define CLONE_NEWUTS 0x04000000
#endif
#ifndef CLONE_NEWIPC
# define CLONE_NEWIPC 0x08000000
#endif
#ifndef CLONE_NEWNET
# define CLONE_NEWNET 0x40000000
#endif
#ifndef CLONE_NEWUSER
# define CLONE_NEWUSER 0x10000000
#endif
#ifndef CLONE_NEWPID
# define CLONE_NEWPID 0x20000000
#endif
#ifndef MS_RELATIME
#define MS_RELATIME (1 << 21)
#endif
#ifndef MS_STRICTATIME
#define MS_STRICTATIME (1 << 24)
#endif
static void die(char *fmt, ...)
{
va_list ap;
va_start(ap, fmt);
vfprintf(stderr, fmt, ap);
va_end(ap);
exit(EXIT_FAILURE);
}
static void write_file(char *filename, char *fmt, ...)
{
char buf[4096];
int fd;
ssize_t written;
int buf_len;
va_list ap;
va_start(ap, fmt);
buf_len = vsnprintf(buf, sizeof(buf), fmt, ap);
va_end(ap);
if (buf_len < 0) {
die("vsnprintf failed: %s\n",
strerror(errno));
}
if (buf_len >= sizeof(buf)) {
die("vsnprintf output truncated\n");
}
fd = open(filename, O_WRONLY);
if (fd < 0) {
die("open of %s failed: %s\n",
filename, strerror(errno));
}
written = write(fd, buf, buf_len);
if (written != buf_len) {
if (written >= 0) {
die("short write to %s\n", filename);
} else {
die("write to %s failed: %s\n",
filename, strerror(errno));
}
}
if (close(fd) != 0) {
die("close of %s failed: %s\n",
filename, strerror(errno));
}
}
static void create_and_enter_userns(void)
{
uid_t uid;
gid_t gid;
uid = getuid();
gid = getgid();
if (unshare(CLONE_NEWUSER) !=0) {
die("unshare(CLONE_NEWUSER) failed: %s\n",
strerror(errno));
}
write_file("/proc/self/uid_map", "0 %d 1", uid);
write_file("/proc/self/gid_map", "0 %d 1", gid);
if (setgroups(0, NULL) != 0) {
die("setgroups failed: %s\n",
strerror(errno));
}
if (setgid(0) != 0) {
die ("setgid(0) failed %s\n",
strerror(errno));
}
if (setuid(0) != 0) {
die("setuid(0) failed %s\n",
strerror(errno));
}
}
static
bool test_unpriv_remount(int mount_flags, int remount_flags, int invalid_flags)
{
pid_t child;
child = fork();
if (child == -1) {
die("fork failed: %s\n",
strerror(errno));
}
if (child != 0) { /* parent */
pid_t pid;
int status;
pid = waitpid(child, &status, 0);
if (pid == -1) {
die("waitpid failed: %s\n",
strerror(errno));
}
if (pid != child) {
die("waited for %d got %d\n",
child, pid);
}
if (!WIFEXITED(status)) {
die("child did not terminate cleanly\n");
}
return WEXITSTATUS(status) == EXIT_SUCCESS ? true : false;
}
create_and_enter_userns();
if (unshare(CLONE_NEWNS) != 0) {
die("unshare(CLONE_NEWNS) failed: %s\n",
strerror(errno));
}
if (mount("testing", "/tmp", "ramfs", mount_flags, NULL) != 0) {
die("mount of /tmp failed: %s\n",
strerror(errno));
}
create_and_enter_userns();
if (unshare(CLONE_NEWNS) != 0) {
die("unshare(CLONE_NEWNS) failed: %s\n",
strerror(errno));
}
if (mount("/tmp", "/tmp", "none",
MS_REMOUNT | MS_BIND | remount_flags, NULL) != 0) {
/* system("cat /proc/self/mounts"); */
die("remount of /tmp failed: %s\n",
strerror(errno));
}
if (mount("/tmp", "/tmp", "none",
MS_REMOUNT | MS_BIND | invalid_flags, NULL) == 0) {
/* system("cat /proc/self/mounts"); */
die("remount of /tmp with invalid flags "
"succeeded unexpectedly\n");
}
exit(EXIT_SUCCESS);
}
static bool test_unpriv_remount_simple(int mount_flags)
{
return test_unpriv_remount(mount_flags, mount_flags, 0);
}
static bool test_unpriv_remount_atime(int mount_flags, int invalid_flags)
{
return test_unpriv_remount(mount_flags, mount_flags, invalid_flags);
}
int main(int argc, char **argv)
{
if (!test_unpriv_remount_simple(MS_RDONLY|MS_NODEV)) {
die("MS_RDONLY malfunctions\n");
}
if (!test_unpriv_remount_simple(MS_NODEV)) {
die("MS_NODEV malfunctions\n");
}
if (!test_unpriv_remount_simple(MS_NOSUID|MS_NODEV)) {
die("MS_NOSUID malfunctions\n");
}
if (!test_unpriv_remount_simple(MS_NOEXEC|MS_NODEV)) {
die("MS_NOEXEC malfunctions\n");
}
if (!test_unpriv_remount_atime(MS_RELATIME|MS_NODEV,
MS_NOATIME|MS_NODEV))
{
die("MS_RELATIME malfunctions\n");
}
if (!test_unpriv_remount_atime(MS_STRICTATIME|MS_NODEV,
MS_NOATIME|MS_NODEV))
{
die("MS_STRICTATIME malfunctions\n");
}
if (!test_unpriv_remount_atime(MS_NOATIME|MS_NODEV,
MS_STRICTATIME|MS_NODEV))
{
die("MS_RELATIME malfunctions\n");
}
if (!test_unpriv_remount_atime(MS_RELATIME|MS_NODIRATIME|MS_NODEV,
MS_NOATIME|MS_NODEV))
{
die("MS_RELATIME malfunctions\n");
}
if (!test_unpriv_remount_atime(MS_STRICTATIME|MS_NODIRATIME|MS_NODEV,
MS_NOATIME|MS_NODEV))
{
die("MS_RELATIME malfunctions\n");
}
if (!test_unpriv_remount_atime(MS_NOATIME|MS_NODIRATIME|MS_NODEV,
MS_STRICTATIME|MS_NODEV))
{
die("MS_RELATIME malfunctions\n");
}
if (!test_unpriv_remount(MS_STRICTATIME|MS_NODEV, MS_NODEV,
MS_NOATIME|MS_NODEV))
{
die("Default atime malfunctions\n");
}
return EXIT_SUCCESS;
}
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