docker_cli_userns_test.go

// +build !windows

package main

import (
	"fmt"
	"io/ioutil"
	"os"
	"os/exec"
	"path/filepath"
	"strconv"
	"strings"

	"github.com/docker/docker/pkg/integration/checker"
	"github.com/docker/docker/pkg/system"
	"github.com/go-check/check"
)

// user namespaces test: run daemon with remapped root setting
// 1. validate uid/gid maps are set properly
// 2. verify that files created are owned by remapped root
func (s *DockerDaemonSuite) TestDaemonUserNamespaceRootSetting(c *check.C) {
	testRequires(c, DaemonIsLinux, SameHostDaemon, UserNamespaceInKernel)

	c.Assert(s.d.StartWithBusybox("--userns-remap", "default"), checker.IsNil)

	tmpDir, err := ioutil.TempDir("", "userns")
	c.Assert(err, checker.IsNil)

	defer os.RemoveAll(tmpDir)

	// we need to find the uid and gid of the remapped root from the daemon's root dir info
	uidgid := strings.Split(filepath.Base(s.d.root), ".")
	c.Assert(uidgid, checker.HasLen, 2, check.Commentf("Should have gotten uid/gid strings from root dirname: %s", filepath.Base(s.d.root)))
	uid, err := strconv.Atoi(uidgid[0])
	c.Assert(err, checker.IsNil, check.Commentf("Can't parse uid"))
	gid, err := strconv.Atoi(uidgid[1])
	c.Assert(err, checker.IsNil, check.Commentf("Can't parse gid"))

	// writable by the remapped root UID/GID pair
	c.Assert(os.Chown(tmpDir, uid, gid), checker.IsNil)

	out, err := s.d.Cmd("run", "-d", "--name", "userns", "-v", tmpDir+":/goofy", "busybox", "sh", "-c", "touch /goofy/testfile; top")
	c.Assert(err, checker.IsNil, check.Commentf("Output: %s", out))
	user := s.findUser(c, "userns")
	c.Assert(uidgid[0], checker.Equals, user)

	pid, err := s.d.Cmd("inspect", "--format='{{.State.Pid}}'", "userns")
	c.Assert(err, checker.IsNil, check.Commentf("Could not inspect running container: out: %q", pid))
	// check the uid and gid maps for the PID to ensure root is remapped
	// (cmd = cat /proc/<pid>/uid_map | grep -E '0\s+9999\s+1')
	out, rc1, err := runCommandPipelineWithOutput(
		exec.Command("cat", "/proc/"+strings.TrimSpace(pid)+"/uid_map"),
		exec.Command("grep", "-E", fmt.Sprintf("0[[:space:]]+%d[[:space:]]+", uid)))
	c.Assert(rc1, checker.Equals, 0, check.Commentf("Didn't match uid_map: output: %s", out))

	out, rc2, err := runCommandPipelineWithOutput(
		exec.Command("cat", "/proc/"+strings.TrimSpace(pid)+"/gid_map"),
		exec.Command("grep", "-E", fmt.Sprintf("0[[:space:]]+%d[[:space:]]+", gid)))
	c.Assert(rc2, checker.Equals, 0, check.Commentf("Didn't match gid_map: output: %s", out))

	// check that the touched file is owned by remapped uid:gid
	stat, err := system.Stat(filepath.Join(tmpDir, "testfile"))
	c.Assert(err, checker.IsNil)
	c.Assert(stat.UID(), checker.Equals, uint32(uid), check.Commentf("Touched file not owned by remapped root UID"))
	c.Assert(stat.GID(), checker.Equals, uint32(gid), check.Commentf("Touched file not owned by remapped root GID"))

	// use host usernamespace
	out, err = s.d.Cmd("run", "-d", "--name", "userns_skip", "--userns", "host", "busybox", "sh", "-c", "touch /goofy/testfile; top")
	c.Assert(err, checker.IsNil, check.Commentf("Output: %s", out))
	user = s.findUser(c, "userns_skip")
	// userns are skipped, user is root
	c.Assert(user, checker.Equals, "root")
}

// findUser finds the uid or name of the user of the first process that runs in a container
func (s *DockerDaemonSuite) findUser(c *check.C, container string) string {
	out, err := s.d.Cmd("top", container)
	c.Assert(err, checker.IsNil, check.Commentf("Output: %s", out))
	rows := strings.Split(out, "\n")
	if len(rows) < 2 {
		// No process rows founds
		c.FailNow()
	}
	return strings.Fields(rows[1])[0]
}