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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 | #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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