func chuser(username string) (uid, gid int) {
usr, err := user.Lookup(username)
if err != nil {
fmt.Printf("failed to find user %q: %s", username, err)
}
uid, err = strconv.Atoi(usr.Uid)
if err != nil {
fmt.Printf("bad user ID %q: %s", usr.Uid, err)
}
gid, err = strconv.Atoi(usr.Gid)
if err != nil {
fmt.Printf("bad group ID %q: %s", usr.Gid, err)
}
if err := syscall.Setgid(gid); err != nil {
fmt.Printf("setgid(%d): %s", gid, err)
}
if err := syscall.Setuid(uid); err != nil {
fmt.Printf("setuid(%d): %s", uid, err)
}
return uid, gid
}
// SetupUser changes the groups, gid, and uid for the user inside the container
func SetupUser(u string) error {
uid, gid, suppGids, home, err := user.GetUserGroupSupplementaryHome(u, syscall.Getuid(), syscall.Getgid(), "/")
if err != nil {
return fmt.Errorf("get supplementary groups %s", err)
}
if err := syscall.Setgroups(suppGids); err != nil {
return fmt.Errorf("setgroups %s", err)
}
if err := syscall.Setgid(gid); err != nil {
return fmt.Errorf("setgid %s", err)
}
if err := syscall.Setuid(uid); err != nil {
return fmt.Errorf("setuid %s", err)
}
// if we didn't get HOME already, set it based on the user's HOME
if envHome := os.Getenv("HOME"); envHome == "" {
if err := os.Setenv("HOME", home); err != nil {
return fmt.Errorf("set HOME %s", err)
}
}
return nil
}
// Takes care of dropping privileges to the desired user
func changeUser(args *DockerInitArgs) error {
if args.user == "" {
return nil
}
userent, err := utils.UserLookup(args.user)
if err != nil {
return fmt.Errorf("Unable to find user %v: %v", args.user, err)
}
uid, err := strconv.Atoi(userent.Uid)
if err != nil {
return fmt.Errorf("Invalid uid: %v", userent.Uid)
}
gid, err := strconv.Atoi(userent.Gid)
if err != nil {
return fmt.Errorf("Invalid gid: %v", userent.Gid)
}
if err := syscall.Setgid(gid); err != nil {
return fmt.Errorf("setgid failed: %v", err)
}
if err := syscall.Setuid(uid); err != nil {
return fmt.Errorf("setuid failed: %v", err)
}
return nil
}
// Takes care of dropping privileges to the desired user
func changeUser(u string) {
if u == "" {
return
}
userent, err := utils.UserLookup(u)
if err != nil {
log.Fatalf("Unable to find user %v: %v", u, err)
}
uid, err := strconv.Atoi(userent.Uid)
if err != nil {
log.Fatalf("Invalid uid: %v", userent.Uid)
}
gid, err := strconv.Atoi(userent.Gid)
if err != nil {
log.Fatalf("Invalid gid: %v", userent.Gid)
}
if err := syscall.Setgid(gid); err != nil {
log.Fatalf("setgid failed: %v", err)
}
if err := syscall.Setuid(uid); err != nil {
log.Fatalf("setuid failed: %v", err)
}
}
func DropPrivileges(username string) error {
userInfo, err := user.Lookup(username)
if err != nil {
return err
}
uid, err := strconv.Atoi(userInfo.Uid)
if err != nil {
return err
}
gid, err := strconv.Atoi(userInfo.Gid)
if err != nil {
return err
}
// TODO: should set secondary groups too
err = syscall.Setgroups([]int{gid})
if err != nil {
return err
}
err = syscall.Setgid(gid)
if err != nil {
return err
}
err = syscall.Setuid(uid)
if err != nil {
return err
}
return nil
}
// SetupEnv will create pidfile and possibly change the workdir.
func SetupEnv(cfg *config.Config) error {
if cfg.System.User != "" {
// Get the current user
currentUser, err := user.Current()
if err != nil {
return fmt.Errorf("Could not get the current user: %s", err)
}
// If the current user is different than the wanted user, try to change it
if currentUser.Username != cfg.System.User {
wantedUser, err := user.Lookup(cfg.System.User)
if err != nil {
return err
}
uid, err := strconv.Atoi(wantedUser.Uid)
if err != nil {
return fmt.Errorf("Error converting UID [%s] to int: %s", wantedUser.Uid, err)
}
gid, err := strconv.Atoi(wantedUser.Gid)
if err != nil {
return fmt.Errorf("Error converting GID [%s] to int: %s", wantedUser.Gid, err)
}
if err = syscall.Setgid(gid); err != nil {
return fmt.Errorf("Setting group id: %s", err)
}
if err = syscall.Setuid(uid); err != nil {
return fmt.Errorf("Setting user id: %s", err)
}
}
}
if cfg.System.Workdir != "" {
if err := os.Chdir(cfg.System.Workdir); err != nil {
return fmt.Errorf("Could not chdir to '%s': %s", cfg.System.Workdir, err)
}
}
pFile, err := os.Create(cfg.System.Pidfile)
if err != nil {
return err
}
defer pFile.Close()
_, err = pFile.WriteString(fmt.Sprintf("%d", os.Getpid()))
if err != nil {
return err
}
return nil
}
func DropPrivileges(uid int, gid int) (error, bool) {
if err := syscall.Setuid(uid); err != nil {
return err, false
}
if err := syscall.Setgid(gid); err != nil {
return err, false
}
return nil, true
}
// SetRuntimeGroup sets group on what to run as
func SetRuntimeGroup(groupname string) (err error) {
log.Printf("Setting gid to %s", groupname)
gstruct, err := user.LookupGroupId(groupname)
if err != nil {
return
}
egid, _ := strconv.Atoi(gstruct.Gid)
syscall.Setgid(egid)
return
}
func setuid(u string, g string) (err error) {
if len(u) <= 0 {
return
}
uid := -1
gid := -1
for {
userent, err := user.Lookup(u)
if err != nil {
if userent, err = user.LookupId(u); err != nil {
log.Println("Unable to find user", u, err)
break
}
}
uid, err = strconv.Atoi(userent.Uid)
if err != nil {
log.Println("Invalid uid:", userent.Uid)
}
gid, err = strconv.Atoi(userent.Gid)
if err != nil {
log.Println("Invalid gid:", userent.Gid)
}
break
}
if uid < 0 {
uid, err = strconv.Atoi(u)
if err != nil {
log.Println("Invalid uid:", u, err)
return
}
}
if gid < 0 {
gid, err = strconv.Atoi(g)
if err != nil {
log.Println("Invalid gid:", g, err)
return
}
}
if err = syscall.Setgid(gid); err != nil {
log.Println("setgid failed: ", err)
}
if err = syscall.Setuid(uid); err != nil {
log.Println("setuid failed: ", err)
}
return
}
func (s *internalService) DropPrivileges(arg *struct{ R internalDropArg }, result *struct{ R internalDropResult }) error {
if rv := syscall.Setgid(arg.R.Gid); rv != nil {
result.R.SetgidErrno = uintptr(rv.(syscall.Errno))
} else {
result.R.GidDropped = true
}
if rv := syscall.Setuid(arg.R.Uid); rv != nil {
result.R.SetuidErrno = uintptr(rv.(syscall.Errno))
} else {
result.R.UidDropped = true
}
return nil
}
func AttachFiles(containerId, fromFile, toDir, rootDir, perm, uid, gid string) error {
if containerId == "" {
return fmt.Errorf("Please make sure the arguments are not NULL!\n")
}
permInt, err := strconv.Atoi(perm)
if err != nil {
return err
}
// It just need the block device without copying any files
// FIXME whether we need to return an error if the target directory is null
if toDir == "" {
return nil
}
// Make a new file with the given premission and wirte the source file content in it
if _, err := os.Stat(fromFile); err != nil && os.IsNotExist(err) {
return err
}
buf, err := ioutil.ReadFile(fromFile)
if err != nil {
return err
}
targetDir := path.Join(rootDir, containerId, "rootfs", toDir)
_, err = os.Stat(targetDir)
targetFile := targetDir
if err != nil && os.IsNotExist(err) {
// we need to create a target directory with given premission
if err := os.MkdirAll(targetDir, os.FileMode(permInt)); err != nil {
return err
}
targetFile = targetDir + "/" + filepath.Base(fromFile)
} else {
targetFile = targetDir + "/" + filepath.Base(fromFile)
}
err = ioutil.WriteFile(targetFile, buf, os.FileMode(permInt))
if err != nil {
return err
}
user_id, _ := strconv.Atoi(uid)
err = syscall.Setuid(user_id)
if err != nil {
return err
}
group_id, _ := strconv.Atoi(gid)
err = syscall.Setgid(group_id)
if err != nil {
return err
}
return nil
}
func chrootuid(dir, user string) {
pw_filename := "/etc/passwd"
pwf, err := os.Open(pw_filename)
if err != nil {
log.Fatalf("%%Can't open %s: %s", pw_filename, err)
}
pwr := bufio.NewReader(pwf)
for {
line, err := pwr.ReadString('\n')
if err != nil {
log.Fatalf("%%Can't find UID for %s: %s", user, err)
}
pw_row := strings.SplitN(line, ":", 5)
if len(pw_row) != 5 {
continue
}
if pw_row[0] == user {
uid, err = strconv.Atoi(pw_row[2])
if err != nil {
log.Fatalln("%Wrong UID:", err)
}
gid, err = strconv.Atoi(pw_row[3])
if err != nil {
log.Fatalln("%Wrong GID:", err)
}
break
}
}
err = syscall.Chroot(dir)
if err != nil {
log.Fatalln("%Chroot error:", err)
}
err = syscall.Setgid(gid)
if err != nil {
log.Fatalln("%Setgid error:", err)
}
err = syscall.Setuid(uid)
if err != nil {
log.Fatalln("%Setuid error:", err)
}
err = os.Chdir("/")
if err != nil {
log.Fatalln("%Can't cd to '/':", err)
}
}
func MaybeBecomeChildProcess() {
lrs := os.Getenv("_RUNSIT_LAUNCH_INFO")
if lrs == "" {
return
}
defer os.Exit(2) // should never make it this far, though
lr := new(LaunchRequest)
d := gob.NewDecoder(base64.NewDecoder(base64.StdEncoding, strings.NewReader(lrs)))
err := d.Decode(lr)
if err != nil {
log.Fatalf("Failed to decode LaunchRequest in child: %v", err)
}
if lr.NumFiles != 0 {
var lim syscall.Rlimit
if err := syscall.Getrlimit(syscall.RLIMIT_NOFILE, &lim); err != nil {
log.Fatalf("failed to get NOFILE rlimit: %v", err)
}
noFile := rlim_t(lr.NumFiles)
lim.Cur = noFile
lim.Max = noFile
if err := syscall.Setrlimit(syscall.RLIMIT_NOFILE, &lim); err != nil {
log.Fatalf("failed to set NOFILE rlimit: %v", err)
}
}
if lr.Gid != 0 {
if err := syscall.Setgid(lr.Gid); err != nil {
log.Fatalf("failed to Setgid(%d): %v", lr.Gid, err)
}
}
if len(lr.Gids) != 0 {
if err := syscall.Setgroups(lr.Gids); err != nil {
log.Printf("setgroups: %v", err)
}
}
if lr.Uid != 0 {
if err := syscall.Setuid(lr.Uid); err != nil {
log.Fatalf("failed to Setuid(%d): %v", lr.Uid, err)
}
}
if lr.Path != "" {
err = os.Chdir(lr.Dir)
if err != nil {
log.Fatalf("failed to chdir to %q: %v", lr.Dir, err)
}
}
err = syscall.Exec(lr.Path, lr.Argv, lr.Env)
log.Fatalf("failed to exec %q: %v", lr.Path, err)
}
func setgid() error {
exe, err := exec.LookPath(os.Args[0])
if err != nil {
return err
}
st, err := os.Stat(exe)
if err != nil {
return err
}
gid := int(st.Sys().(*syscall.Stat_t).Gid)
return syscall.Setgid(gid)
}
// Init create pid file, set working dir, setgid and setuid.
func Init(userGroup, dir, pidFile string) error {
// change working dir
if err := os.Chdir(dir); err != nil {
return err
}
// create pid file
if err := ioutil.WriteFile(pidFile, []byte(fmt.Sprintf("%d\n", os.Getpid())), 0644); err != nil {
return err
}
// setuid and setgid
ug := strings.SplitN(userGroup, " ", 2)
usr := defaultUser
grp := defaultGroup
if len(ug) == 0 {
// default user and group (nobody)
} else if len(ug) == 1 {
usr = ug[0]
grp = ""
} else if len(ug) == 2 {
usr = ug[0]
grp = ug[1]
}
uid := 0
gid := 0
ui, err := user.Lookup(usr)
if err != nil {
return err
}
uid, _ = strconv.Atoi(ui.Uid)
// group no set
if grp == "" {
gid, _ = strconv.Atoi(ui.Gid)
} else {
// use user's group instread
// TODO LookupGroup
gid, _ = strconv.Atoi(ui.Gid)
}
if err := syscall.Setgid(gid); err != nil {
return err
}
if err := syscall.Setuid(uid); err != nil {
return err
}
return nil
}
func main() {
var Hostname, User, DatabaseFile, VoicemailDirectory, HttpPort, SmtpPort string
var Limit int
flag.StringVar(&Hostname, "host", "localhost", "Hostname or IP to bind to")
flag.StringVar(&User, "user", "nobody", "User to drop to after binding")
flag.StringVar(&DatabaseFile, "database", "./voicemail.sqlite", "Database file location")
flag.StringVar(&VoicemailDirectory, "voicemail", "./mp3/", "Voicemail storage directory")
flag.StringVar(&HttpPort, "http-port", "8080", "Port for the HTTP service")
flag.StringVar(&SmtpPort, "smtp-port", "2500", "Port for the SMTP service")
flag.IntVar(&Limit, "limit", -1, "Only display this many voicemails in the web interface")
flag.Parse()
smtpListener, err := net.Listen("tcp", Hostname+":"+SmtpPort)
if err != nil {
logger.Panic(err)
}
httpListener, err := net.Listen("tcp", Hostname+":"+HttpPort)
if err != nil {
logger.Panic(err)
}
u, err := user.Lookup(User)
if err != nil {
logger.Panic(err)
}
uid, _ := strconv.Atoi(u.Uid)
gid, _ := strconv.Atoi(u.Gid)
if err = syscall.Setgid(gid); err != nil {
logger.Panic(err)
}
if err = syscall.Setuid(uid); err != nil {
logger.Panic(err)
}
db := model.OpenDatabase(DatabaseFile, VoicemailDirectory)
go mail.Serve(smtpListener, db)
web.Serve(httpListener, db, VoicemailDirectory, Limit)
}
func main() {
exedir := flag.String("dir", "/", "directory to chroot to.")
uid := flag.Int("uid", 0, "uid to use.")
gid := flag.Int("gid", 0, "gid to use.")
binary := flag.String("binary", "", "full path of binary.")
flag.Parse()
if len(flag.Args()) < 2 {
log.Fatal("use: chroot DIR COMMAND [ARG ..]")
}
args := flag.Args()[1:]
dir := flag.Arg(0)
en := syscall.Chroot(dir)
if en != 0 {
log.Fatalln("Chroot error:", os.Errno(en))
}
en = syscall.Setgid(*gid)
if en != 0 {
log.Fatalln("Setgid error:", os.Errno(en))
}
en = syscall.Setuid(*uid)
if en != 0 {
log.Fatalln("Setuid error:", os.Errno(en))
}
err := os.Chdir(*exedir)
if err != nil {
log.Fatalln("Can't cd to", *exedir, err)
}
bin := *binary
if bin == "" {
bin = args[0]
}
en = syscall.Exec(bin, args, os.Environ())
if en != 0 {
log.Fatalln("Can't exec", args, os.Errno(en))
}
}
func (t *pty) fork(file string, args, env []string, cwd string, cols, rows, uid, gid int) error {
var winp = new(C.struct_winsize)
winp.ws_col = C.ushort(cols)
winp.ws_row = C.ushort(rows)
winp.ws_xpixel = 0
winp.ws_ypixel = 0
//fork the pty
var master C.int = -1
var name []C.char = make([]C.char, 40)
var pid C.int = C.GoForkpty(&master, &name[0], winp)
t.fd = int(master)
t.pid = int(pid)
t.pty = C.GoString(&name[0])
switch t.pid {
case -1:
return errors.New("forkpty(3) failed")
case 0:
if cwd != "" {
if err := syscall.Chdir(cwd); err != nil {
panic("chdir failed")
}
}
if uid != -1 && gid != -1 {
if err := syscall.Setgid(gid); err != nil {
panic("setgid failed")
}
if err := syscall.Setuid(uid); err != nil {
panic("setuid failed")
}
}
syscall.Exec(file, args, env)
panic("exec failed")
}
return nil
}
func main() {
// NOTE: Sandbox doesn't work correctly with /more/ than 1 goroutine!
runtime.GOMAXPROCS(1)
// Open the port, to be used later...
log.Printf("Opening port...")
l, e := net.Listen("tcp", ":80")
if e != nil {
log.Fatal(e.Error())
}
// Chroot into /jailed
os.Chdir("/jailed")
e = syscall.Chroot("/jailed")
if e != nil {
log.Fatal("Failed to chroot: %v", e.Error())
}
// Drop group (group must be done first, apparently?)
e = syscall.Setgid(9999)
if e != nil {
log.Fatal("Failed to drop group: %v", e.Error())
}
// Drop user
e = syscall.Setuid(9999)
if e != nil {
log.Fatal("Failed to drop user: %v", e.Error())
}
// Handle pages
http.HandleFunc("/", indexHandler)
http.HandleFunc("/nyancat.gif", nyanHandler)
http.HandleFunc("/bd8d1dda5442e2888b7633335cd38f39a95db855", badSyscallHandler) // TODO: DELETE ME
// Enable seccomp filtering
Sandbox()
// Begin serving on the previously-opened socket
log.Printf("Starting web server.")
http.Serve(l, nil)
}
// SetupUser changes the groups, gid, and uid for the user inside the container
func SetupUser(u string) error {
uid, gid, suppGids, err := user.GetUserGroupSupplementary(u, syscall.Getuid(), syscall.Getgid())
if err != nil {
return fmt.Errorf("get supplementary groups %s", err)
}
if err := syscall.Setgroups(suppGids); err != nil {
return fmt.Errorf("setgroups %s", err)
}
if err := syscall.Setgid(gid); err != nil {
return fmt.Errorf("setgid %s", err)
}
if err := syscall.Setuid(uid); err != nil {
return fmt.Errorf("setuid %s", err)
}
return nil
}
func (db *DB) readDB(filename string) (r []string, err error) {
var fb []byte
func() {
gid := syscall.Getgid()
if setgid() != nil {
defer syscall.Setgid(gid)
}
fb, err = ioutil.ReadFile(filename)
}()
if err != nil {
return
}
if bytes.Compare(fb[0:8], []byte("\x00mlocate")) == 0 {
return db.readMlocateDB(fb)
}
return
}
// Takes care of dropping privileges to the desired user
func changeUser(args *execdriver.InitArgs) error {
uid, gid, suppGids, err := user.GetUserGroupSupplementary(
args.User,
syscall.Getuid(), syscall.Getgid(),
)
if err != nil {
return err
}
if err := syscall.Setgroups(suppGids); err != nil {
return fmt.Errorf("Setgroups failed: %v", err)
}
if err := syscall.Setgid(gid); err != nil {
return fmt.Errorf("Setgid failed: %v", err)
}
if err := syscall.Setuid(uid); err != nil {
return fmt.Errorf("Setuid failed: %v", err)
}
return nil
}
func Secure(uid, gid int) {
debug("Enabled.")
if syscall.Getuid() != 0 {
debug("Not running as sudo.")
return
}
// set group id first as you need to be root to change group
debug("Setting GID (group id) to %v", gid)
err := syscall.Setgid(gid)
if err != nil {
debug("Fatal: Failed to set group id: %v", err)
debug(" Use -gid parameter to specify the correct group id.")
}
debug("Setting UID (user id) to %v", gid)
err = syscall.Setuid(uid)
if err != nil {
debug("Fatal: Failed to set user id: %v", err)
debug(" Use -uid parameter to specify the correct user id.")
}
}
func DropPrivileges() error {
var err error
if !_ConfigMeta.IsDefined("runoptions", "uid") {
// not found, no dropping privileges but no err
return nil
}
if !_ConfigMeta.IsDefined("runoptions", "gid") {
return MsgError("GID must be specified for dropping privileges")
}
INFO("Switching to user: %d.%d", _Config.RunOptions.Uid, _Config.RunOptions.Gid)
if err = syscall.Setgid(_Config.RunOptions.Gid); err != nil {
return MsgError("setgid: %s", err.Error())
}
if err = syscall.Setuid(_Config.RunOptions.Uid); err != nil {
return MsgError("setuid: %s", err.Error())
}
return nil
}
func DropPrivileges(username string, groupname string) (err error) {
uid, err := GetUidByName(username)
if err != nil {
return
}
gid, err := GetGidByName(groupname)
if err != nil {
return
}
err = syscall.Setgid(gid)
if err != nil {
return
}
log.Printf("Dropped group privileges")
err = syscall.Setuid(uid)
if err != nil {
return
}
log.Printf("Dropped user privileges")
return
}
func DropPrivileges(config RunOptions) error {
var err error
if config.Uid == nil {
// not found, no dropping privileges but no err
return nil
}
if config.Gid == nil {
return errors.New("GID must be specified for dropping privileges")
}
logp.Info("Switching to user: %d.%d", config.Uid, config.Gid)
if err = syscall.Setgid(*config.Gid); err != nil {
return fmt.Errorf("setgid: %s", err.Error())
}
if err = syscall.Setuid(*config.Uid); err != nil {
return fmt.Errorf("setuid: %s", err.Error())
}
return nil
}
func Setgid(gid int) error {
return syscall.Setgid(gid)
}
// Activates the mitigation measurements.
func Activate(uid int, gid int, path string) {
if !CanActivate() {
panic("Cannot activate mitigation measurements!")
}
// chroot directory
err := syscall.Chroot(path)
if err != nil {
panic(err)
}
// change directory to new /
err = syscall.Chdir("/")
if err != nil {
panic(err)
}
// drop all other groups
err = syscall.Setgroups([]int{gid})
if err != nil {
panic(err)
}
// verify the empty group list
gids, err := syscall.Getgroups()
if err != nil {
panic("Could not read groups!")
}
if len(gids) > 1 {
panic("Could not drop groups!")
} else if len(gids) == 1 {
if gids[0] != gid {
panic("Could not drop foreign groups!")
}
}
// change group
err = syscall.Setgid(gid)
if err != nil {
panic(err)
}
// verify the group change
ngid := syscall.Getgid()
if ngid != gid {
panic("Could not change group id!")
}
// change user
err = syscall.Setuid(uid)
if err != nil {
panic(err)
}
// verify the user change
nuid := syscall.Getuid()
if nuid != uid {
panic("Could not change user id!")
}
// now drop all environment variables
os.Clearenv()
}
func Setgid(gid int) (err error) {
return syscall.Setgid(gid)
}
func (k *PosixKernel) Setgid(gid int) int {
// TODO: doesn't work on Linux
syscall.Setgid(gid)
return 0
}
