Golang syscall.Fchown函數代碼示例

// setup standard pipes so that the TTY of the calling runc process
// is not inherited by the container.
func createStdioPipes(p *libcontainer.Process, rootuid int) (*tty, error) {
	var (
		t   = &tty{}
		fds []int
	)
	r, w, err := os.Pipe()
	if err != nil {
		return nil, err
	}
	fds = append(fds, int(r.Fd()), int(w.Fd()))
	go io.Copy(w, os.Stdin)
	t.closers = append(t.closers, w)
	p.Stdin = r
	if r, w, err = os.Pipe(); err != nil {
		return nil, err
	}
	fds = append(fds, int(r.Fd()), int(w.Fd()))
	go io.Copy(os.Stdout, r)
	p.Stdout = w
	t.closers = append(t.closers, r)
	if r, w, err = os.Pipe(); err != nil {
		return nil, err
	}
	fds = append(fds, int(r.Fd()), int(w.Fd()))
	go io.Copy(os.Stderr, r)
	p.Stderr = w
	t.closers = append(t.closers, r)
	// change the ownership of the pipe fds incase we are in a user namespace.
	for _, fd := range fds {
		if err := syscall.Fchown(fd, rootuid, rootuid); err != nil {
			return nil, err
		}
	}
	return t, nil
}

// fixStdioPermissions fixes the permissions of PID 1's STDIO within the container to the specified user.
// The ownership needs to match because it is created outside of the container and needs to be
// localized.
func fixStdioPermissions(u *user.ExecUser) error {
	var null syscall.Stat_t
	if err := syscall.Stat("/dev/null", &null); err != nil {
		return err
	}
	for _, fd := range []uintptr{
		os.Stdin.Fd(),
		os.Stderr.Fd(),
		os.Stdout.Fd(),
	} {
		var s syscall.Stat_t
		if err := syscall.Fstat(int(fd), &s); err != nil {
			return err
		}
		// Skip chown of /dev/null if it was used as one of the STDIO fds.
		if s.Rdev == null.Rdev {
			continue
		}
		// We only change the uid owner (as it is possible for the mount to
		// prefer a different gid, and there's no reason for us to change it).
		// The reason why we don't just leave the default uid=X mount setup is
		// that users expect to be able to actually use their console. Without
		// this code, you couldn't effectively run as a non-root user inside a
		// container and also have a console set up.
		if err := syscall.Fchown(int(fd), u.Uid, int(s.Gid)); err != nil {
			return err
		}
	}
	return nil
}

// Chown changes the numeric uid and gid of the named file.
// If there is an error, it will be of type *PathError.
func (f *File) Chown(uid, gid int) error {
	if f == nil {
		return ErrInvalid
	}
	if e := syscall.Fchown(f.fd, uid, gid); e != nil {
		return &PathError{"chown", f.name, e}
	}
	return nil
}

// setupUser changes the groups, gid, and uid for the user inside the container
func setupUser(config *initConfig) error {
	// Set up defaults.
	defaultExecUser := user.ExecUser{
		Uid:  syscall.Getuid(),
		Gid:  syscall.Getgid(),
		Home: "/",
	}
	passwdPath, err := user.GetPasswdPath()
	if err != nil {
		return err
	}
	groupPath, err := user.GetGroupPath()
	if err != nil {
		return err
	}
	execUser, err := user.GetExecUserPath(config.User, &defaultExecUser, passwdPath, groupPath)
	if err != nil {
		return err
	}

	var addGroups []int
	if len(config.Config.AdditionalGroups) > 0 {
		addGroups, err = user.GetAdditionalGroupsPath(config.Config.AdditionalGroups, groupPath)
		if err != nil {
			return err
		}
	}
	// change the permissions on the STDIO of the current process so that when the user
	// is changed for the container, it's STDIO of the process matches the user.
	for _, fd := range []uintptr{
		os.Stdin.Fd(),
		os.Stderr.Fd(),
		os.Stdout.Fd(),
	} {
		if err := syscall.Fchown(int(fd), execUser.Uid, execUser.Gid); err != nil {
			return err
		}
	}
	suppGroups := append(execUser.Sgids, addGroups...)
	if err := syscall.Setgroups(suppGroups); err != nil {
		return err
	}

	if err := system.Setgid(execUser.Gid); err != nil {
		return err
	}
	if err := system.Setuid(execUser.Uid); err != nil {
		return 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", execUser.Home); err != nil {
			return err
		}
	}
	return nil
}

// Chown changes the numeric uid and gid of the named file.
// If there is an error, it will be of type *PathError.
func (f *File) Chown(uid, gid int) error {
	if err := f.checkValid("chown"); err != nil {
		return err
	}
	if e := syscall.Fchown(f.fd, uid, gid); e != nil {
		return &PathError{"chown", f.name, e}
	}
	return nil
}

func RestrictedChown(cwdFd int, file string, origStat os.FileInfo, uid, gid, reqUid, reqGid int) RCHStatus {

	status := RCOK
	openflags := syscall.O_NONBLOCK | syscall.O_NOCTTY

	if reqUid == -1 && reqGid == 1 {
		return RCDoOrdinaryChown
	}

	if !origStat.Mode().IsRegular() {
		if !origStat.Mode().IsDir() {
			return RCDoOrdinaryChown
		}
		openflags |= syscall.O_DIRECTORY
	}

	fd, err := syscall.Openat(cwdFd, file, syscall.O_RDONLY|openflags, 0)

	if !(0 <= fd ||
		err == syscall.EACCES &&
			origStat.Mode().IsRegular()) {

		if fd, err = syscall.Openat(cwdFd, file, syscall.O_WRONLY|openflags, 0); 0 > fd {

			if err == syscall.EACCES {
				return RCDoOrdinaryChown
			}
			return RCError
		}
	}

	var stat syscall.Stat_t
	if err := syscall.Fstat(fd, &stat); err != nil {
		status = RCError
	} else if !sameFile(origStat.Sys().(*syscall.Stat_t), &stat) {
		status = RCInodeChanged
	} else if reqUid == -1 || uint32(reqUid) == stat.Uid &&
		(reqGid == -1 || uint32(reqGid) == stat.Gid) {
		if syscall.Fchown(fd, uid, gid) == nil {
			if syscall.Close(fd) == nil {
				return RCOK
			}
			return RCError
		} else {
			status = RCError
		}
	}

	return status
}

func dupStdio(process *libcontainer.Process, rootuid int) error {
	process.Stdin = os.Stdin
	process.Stdout = os.Stdout
	process.Stderr = os.Stderr
	for _, fd := range []uintptr{
		os.Stdin.Fd(),
		os.Stdout.Fd(),
		os.Stderr.Fd(),
	} {
		if err := syscall.Fchown(int(fd), rootuid, rootuid); err != nil {
			return err
		}
	}
	return nil
}

func chownFds(uid, gid int) error {
	fdList, err := ioutil.ReadDir("/proc/self/fd")
	if err != nil {
		return err
	}
	for _, fi := range fdList {
		fd, err := strconv.Atoi(fi.Name())
		if err != nil {
			// ignore non-numeric file names
			continue
		}

		if err = syscall.Fchown(fd, uid, gid); err != nil {
			// "bad file descriptor" probably just means it no longer exists since we did "readdir", so ignore that
			if err != syscall.EBADF {
				return err
			}
		}
	}
	return nil
}

// InitializeIO creates pipes for use with the process's STDIO
// and returns the opposite side for each
func (p *Process) InitializeIO(rootuid int) (i *IO, err error) {
	var fds []uintptr
	i = &IO{}
	// cleanup in case of an error
	defer func() {
		if err != nil {
			for _, fd := range fds {
				syscall.Close(int(fd))
			}
		}
	}()
	// STDIN
	r, w, err := os.Pipe()
	if err != nil {
		return nil, err
	}
	fds = append(fds, r.Fd(), w.Fd())
	p.Stdin, i.Stdin = r, w
	// STDOUT
	if r, w, err = os.Pipe(); err != nil {
		return nil, err
	}
	fds = append(fds, r.Fd(), w.Fd())
	p.Stdout, i.Stdout = w, r
	// STDERR
	if r, w, err = os.Pipe(); err != nil {
		return nil, err
	}
	fds = append(fds, r.Fd(), w.Fd())
	p.Stderr, i.Stderr = w, r
	// change ownership of the pipes incase we are in a user namespace
	for _, fd := range fds {
		if err := syscall.Fchown(int(fd), rootuid, rootuid); err != nil {
			return nil, err
		}
	}
	return i, nil
}

// fixStdioPermissions fixes the permissions of PID 1's STDIO within the container to the specified user.
// The ownership needs to match because it is created outside of the container and needs to be
// localized.
func fixStdioPermissions(u *user.ExecUser) error {
	var null syscall.Stat_t
	if err := syscall.Stat("/dev/null", &null); err != nil {
		return err
	}
	for _, fd := range []uintptr{
		os.Stdin.Fd(),
		os.Stderr.Fd(),
		os.Stdout.Fd(),
	} {
		var s syscall.Stat_t
		if err := syscall.Fstat(int(fd), &s); err != nil {
			return err
		}
		// skip chown of /dev/null if it was used as one of the STDIO fds.
		if s.Rdev == null.Rdev {
			continue
		}
		if err := syscall.Fchown(int(fd), u.Uid, u.Gid); err != nil {
			return err
		}
	}
	return nil
}

// Chown changes the numeric uid and gid of the named file.
func (f *File) Chown(uid, gid int) Error {
	if e := syscall.Fchown(f.fd, uid, gid); e != 0 {
		return &PathError{"chown", f.name, Errno(e)}
	}
	return nil
}

//.........這裏部分代碼省略.........
	if processConfig.Tty {
		cons, err := p.NewConsole(rootuid)
		if err != nil {
			return writers, err
		}
		term, err := NewTtyConsole(cons, pipes)
		if err != nil {
			return writers, err
		}
		processConfig.Terminal = term
		return writers, nil
	}
	// not a tty--set up stdio pipes
	term := &execdriver.StdConsole{}
	processConfig.Terminal = term

	// if we are not in a user namespace, there is no reason to go through
	// the hassle of setting up os-level pipes with proper (remapped) ownership
	// so we will do the prior shortcut for non-userns containers
	if rootuid == 0 {
		p.Stdout = pipes.Stdout
		p.Stderr = pipes.Stderr

		r, w, err := os.Pipe()
		if err != nil {
			return writers, err
		}
		if pipes.Stdin != nil {
			go func() {
				io.Copy(w, pipes.Stdin)
				w.Close()
			}()
			p.Stdin = r
		}
		return writers, nil
	}

	// if we have user namespaces enabled (rootuid != 0), we will set
	// up os pipes for stderr, stdout, stdin so we can chown them to
	// the proper ownership to allow for proper access to the underlying
	// fds
	var fds []uintptr

	copyPipes := func(out io.Writer, in io.ReadCloser) {
		defer wg.Done()
		io.Copy(out, in)
		in.Close()
	}

	//setup stdout
	r, w, err := os.Pipe()
	if err != nil {
		w.Close()
		return writers, err
	}
	writers = append(writers, w)
	fds = append(fds, r.Fd(), w.Fd())
	if pipes.Stdout != nil {
		wg.Add(1)
		go copyPipes(pipes.Stdout, r)
	}
	term.Closers = append(term.Closers, r)
	p.Stdout = w

	//setup stderr
	r, w, err = os.Pipe()
	if err != nil {
		w.Close()
		return writers, err
	}
	writers = append(writers, w)
	fds = append(fds, r.Fd(), w.Fd())
	if pipes.Stderr != nil {
		wg.Add(1)
		go copyPipes(pipes.Stderr, r)
	}
	term.Closers = append(term.Closers, r)
	p.Stderr = w

	//setup stdin
	r, w, err = os.Pipe()
	if err != nil {
		r.Close()
		return writers, err
	}
	fds = append(fds, r.Fd(), w.Fd())
	if pipes.Stdin != nil {
		go func() {
			io.Copy(w, pipes.Stdin)
			w.Close()
		}()
		p.Stdin = r
	}
	for _, fd := range fds {
		if err := syscall.Fchown(int(fd), rootuid, rootuid); err != nil {
			return writers, fmt.Errorf("Failed to chown pipes fd: %v", err)
		}
	}
	return writers, nil
}

func (fs *Fs) wstatPost(fid *Fid, cur *Dir, next *Dir) error {

	defer fid.file.unlock()

	// Rename the file.
	if next.Name != "" &&
		next.Name != cur.Name {

		new_path := path.Join(path.Dir(fid.Path), next.Name)
		err := fid.file.rename(fs, fid.Path, new_path)
		if err != nil {
			return err
		}
	}

	// Update our access times.
	atime := cur.Atime
	mtime := cur.Atime
	if next.Atime != math.MaxUint32 {
		atime = next.Atime
	}
	if next.Mtime != math.MaxUint32 {
		mtime = next.Mtime
	}
	if atime != cur.Atime || mtime != cur.Mtime {
		err := syscall.Futimes(
			fid.file.write_fd,
			[]syscall.Timeval{
				syscall.Timeval{int64(atime), 0},
				syscall.Timeval{int64(mtime), 0},
			})
		if err != nil {
			return err
		}
	}

	// Truncate the file.
	if next.Length != math.MaxUint64 &&
		next.Length != cur.Length {
		err := syscall.Ftruncate(fid.file.write_fd, int64(next.Length))
		if err != nil {
			return err
		}
	}

	// Change the owner.
	uid := cur.Uidnum
	gid := cur.Gidnum
	if next.Uidnum != math.MaxUint32 &&
		next.Uidnum != cur.Uidnum {
		uid = next.Uidnum
	}
	if next.Gidnum != math.MaxUint32 &&
		next.Gidnum != cur.Gidnum {
		gid = next.Gidnum
	}
	if uid != cur.Uidnum || gid != cur.Gidnum {
		err := syscall.Fchown(fid.file.write_fd, int(uid), int(gid))
		if err != nil {
			return err
		}
	}

	return nil
}

// Run as pid 1 and monitor the contained process to return its exit code.
func containerInitApp(c *Config, logFile *os.File) error {
	log := logger.New()

	init := newContainerInit(c, logFile)
	log.Debug("registering RPC server")
	if err := rpcplus.Register(init); err != nil {
		log.Error("error registering RPC server", "err", err)
		return err
	}
	init.mtx.Lock()
	defer init.mtx.Unlock()

	// Prepare the cmd based on the given args
	// If this fails we report that below
	cmdPath, cmdErr := getCmdPath(c)
	cmd := exec.Command(cmdPath, c.Args[1:]...)
	cmd.Dir = c.WorkDir

	cmd.Env = make([]string, 0, len(c.Env))
	for k, v := range c.Env {
		cmd.Env = append(cmd.Env, k+"="+v)
	}

	// App runs in its own session
	cmd.SysProcAttr = &syscall.SysProcAttr{Setsid: true}

	if c.Uid != nil || c.Gid != nil {
		cmd.SysProcAttr.Credential = &syscall.Credential{}
		if c.Uid != nil {
			cmd.SysProcAttr.Credential.Uid = *c.Uid
		}
		if c.Gid != nil {
			cmd.SysProcAttr.Credential.Gid = *c.Gid
		}
	}

	// Console setup.  Hook up the container app's stdin/stdout/stderr to
	// either a pty or pipes.  The FDs for the controlling side of the
	// pty/pipes will be passed to flynn-host later via a UNIX socket.
	if c.TTY {
		log.Debug("creating PTY")
		ptyMaster, ptySlave, err := pty.Open()
		if err != nil {
			log.Error("error creating PTY", "err", err)
			return err
		}
		init.ptyMaster = ptyMaster
		cmd.Stdout = ptySlave
		cmd.Stderr = ptySlave
		if c.OpenStdin {
			log.Debug("attaching stdin to PTY")
			cmd.Stdin = ptySlave
			cmd.SysProcAttr.Setctty = true
		}
		if c.Uid != nil && c.Gid != nil {
			if err := syscall.Fchown(int(ptySlave.Fd()), int(*c.Uid), int(*c.Gid)); err != nil {
				log.Error("error changing PTY ownership", "err", err)
				return err
			}
		}
	} else {
		// We copy through a socketpair (rather than using cmd.StdoutPipe directly) to make
		// it easier for flynn-host to do non-blocking I/O (via net.FileConn) so that no
		// read(2) calls can succeed after closing the logs during an update.
		//
		// We also don't assign the socketpair directly to fd 1 because that prevents jobs
		// using /dev/stdout (calling open(2) on a socket leads to an ENXIO error, see
		// http://marc.info/?l=ast-users&m=120978595414993).
		newPipe := func(pipeFn func() (io.ReadCloser, error), name string) (*os.File, error) {
			pipe, err := pipeFn()
			if err != nil {
				return nil, err
			}
			if c.Uid != nil && c.Gid != nil {
				if err := syscall.Fchown(int(pipe.(*os.File).Fd()), int(*c.Uid), int(*c.Gid)); err != nil {
					return nil, err
				}
			}
			sockR, sockW, err := newSocketPair(name)
			if err != nil {
				return nil, err
			}
			go func() {
				defer sockW.Close()
				for {
					// copy data from the pipe to the socket using splice(2)
					// (rather than io.Copy) to avoid a needless copy through
					// user space
					n, err := syscall.Splice(int(pipe.(*os.File).Fd()), nil, int(sockW.Fd()), nil, 65535, 0)
					if err != nil || n == 0 {
						return
					}
				}
			}()
			return sockR, nil
		}

		log.Debug("creating stdout pipe")
		var err error
//.........這裏部分代碼省略.........

func (k *PosixKernel) Fchown(fd, uid, gid int) uint64 {
	return Errno(syscall.Fchown(fd, uid, gid))
}