Vendor in latest github.com/projectatomic/buildah

This adds support for Dockerfile.in and fixes some limits
issues on docker build

Also adds support for podman build to read Dockerfile from stdin.

cat Dockerfile | podman build -f - .

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

Closes: #1209
Approved by: mheon

7 files changed, 1475 insertions, 0 deletions

diff --git a/vendor/github.com/projectatomic/buildah/chroot/run.go b/vendor/github.com/projectatomic/buildah/chroot/run.go
new file mode 100644
index 000000000..77709c52d
--- /dev/null
+++ b/vendor/github.com/projectatomic/buildah/chroot/run.go
@@ -0,0 +1,1248 @@
+// +build linux
+
+package chroot
+
+import (
+	"bytes"
+	"encoding/json"
+	"fmt"
+	"io"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"runtime"
+	"strconv"
+	"strings"
+	"sync"
+	"syscall"
+	"unsafe"
+
+	"github.com/containers/storage/pkg/ioutils"
+	"github.com/containers/storage/pkg/mount"
+	"github.com/containers/storage/pkg/reexec"
+	"github.com/opencontainers/runc/libcontainer/apparmor"
+	"github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+	"github.com/projectatomic/buildah/bind"
+	"github.com/projectatomic/buildah/unshare"
+	"github.com/projectatomic/buildah/util"
+	"github.com/sirupsen/logrus"
+	"github.com/syndtr/gocapability/capability"
+	"golang.org/x/crypto/ssh/terminal"
+	"golang.org/x/sys/unix"
+)
+
+const (
+	// runUsingChrootCommand is a command we use as a key for reexec
+	runUsingChrootCommand = "buildah-chroot-runtime"
+	// runUsingChrootExec is a command we use as a key for reexec
+	runUsingChrootExecCommand = "buildah-chroot-exec"
+)
+
+var (
+	rlimitsMap = map[string]int{
+		"RLIMIT_AS":         unix.RLIMIT_AS,
+		"RLIMIT_CORE":       unix.RLIMIT_CORE,
+		"RLIMIT_CPU":        unix.RLIMIT_CPU,
+		"RLIMIT_DATA":       unix.RLIMIT_DATA,
+		"RLIMIT_FSIZE":      unix.RLIMIT_FSIZE,
+		"RLIMIT_LOCKS":      unix.RLIMIT_LOCKS,
+		"RLIMIT_MEMLOCK":    unix.RLIMIT_MEMLOCK,
+		"RLIMIT_MSGQUEUE":   unix.RLIMIT_MSGQUEUE,
+		"RLIMIT_NICE":       unix.RLIMIT_NICE,
+		"RLIMIT_NOFILE":     unix.RLIMIT_NOFILE,
+		"RLIMIT_NPROC":      unix.RLIMIT_NPROC,
+		"RLIMIT_RSS":        unix.RLIMIT_RSS,
+		"RLIMIT_RTPRIO":     unix.RLIMIT_RTPRIO,
+		"RLIMIT_RTTIME":     unix.RLIMIT_RTTIME,
+		"RLIMIT_SIGPENDING": unix.RLIMIT_SIGPENDING,
+		"RLIMIT_STACK":      unix.RLIMIT_STACK,
+	}
+	rlimitsReverseMap = map[int]string{}
+)
+
+func init() {
+	reexec.Register(runUsingChrootCommand, runUsingChrootMain)
+	reexec.Register(runUsingChrootExecCommand, runUsingChrootExecMain)
+	for limitName, limitNumber := range rlimitsMap {
+		rlimitsReverseMap[limitNumber] = limitName
+	}
+}
+
+type runUsingChrootSubprocOptions struct {
+	Spec        *specs.Spec
+	BundlePath  string
+	UIDMappings []syscall.SysProcIDMap
+	GIDMappings []syscall.SysProcIDMap
+}
+
+type runUsingChrootExecSubprocOptions struct {
+	Spec       *specs.Spec
+	BundlePath string
+}
+
+// RunUsingChroot runs a chrooted process, using some of the settings from the
+// passed-in spec, and using the specified bundlePath to hold temporary files,
+// directories, and mountpoints.
+func RunUsingChroot(spec *specs.Spec, bundlePath string, stdin io.Reader, stdout, stderr io.Writer) (err error) {
+	var confwg sync.WaitGroup
+
+	runtime.LockOSThread()
+	defer runtime.UnlockOSThread()
+
+	// Write the runtime configuration, mainly for debugging.
+	specbytes, err := json.Marshal(spec)
+	if err != nil {
+		return err
+	}
+	if err = ioutils.AtomicWriteFile(filepath.Join(bundlePath, "config.json"), specbytes, 0600); err != nil {
+		return errors.Wrapf(err, "error storing runtime configuration")
+	}
+
+	// Run the grandparent subprocess in a user namespace that reuses the mappings that we have.
+	uidmap, gidmap, err := util.GetHostIDMappings("")
+	if err != nil {
+		return err
+	}
+	for i := range uidmap {
+		uidmap[i].HostID = uidmap[i].ContainerID
+	}
+	for i := range gidmap {
+		gidmap[i].HostID = gidmap[i].ContainerID
+	}
+
+	// Default to using stdin/stdout/stderr if we weren't passed objects to use.
+	if stdin == nil {
+		stdin = os.Stdin
+	}
+	if stdout == nil {
+		stdout = os.Stdout
+	}
+	if stderr == nil {
+		stderr = os.Stderr
+	}
+
+	// Create a pipe for passing configuration down to the next process.
+	preader, pwriter, err := os.Pipe()
+	if err != nil {
+		return errors.Wrapf(err, "error creating configuration pipe")
+	}
+	config, conferr := json.Marshal(runUsingChrootSubprocOptions{
+		Spec:       spec,
+		BundlePath: bundlePath,
+	})
+	if conferr != nil {
+		return errors.Wrapf(conferr, "error encoding configuration for %q", runUsingChrootCommand)
+	}
+
+	// Set our terminal's mode to raw, to pass handling of special
+	// terminal input to the terminal in the container.
+	if spec.Process.Terminal && terminal.IsTerminal(unix.Stdin) {
+		state, err := terminal.MakeRaw(unix.Stdin)
+		if err != nil {
+			logrus.Warnf("error setting terminal state: %v", err)
+		} else {
+			defer func() {
+				if err = terminal.Restore(unix.Stdin, state); err != nil {
+					logrus.Errorf("unable to restore terminal state: %v", err)
+				}
+			}()
+		}
+	}
+
+	// Raise any resource limits that are higher than they are now, before
+	// we drop any more privileges.
+	if err = setRlimits(spec, false, true); err != nil {
+		return err
+	}
+
+	// Start the grandparent subprocess.
+	cmd := unshare.Command(runUsingChrootCommand)
+	cmd.Stdin, cmd.Stdout, cmd.Stderr = stdin, stdout, stderr
+	cmd.Dir = "/"
+	cmd.Env = append([]string{fmt.Sprintf("LOGLEVEL=%d", logrus.GetLevel())}, os.Environ()...)
+	cmd.UnshareFlags = syscall.CLONE_NEWUSER
+	cmd.UidMappings = uidmap
+	cmd.GidMappings = gidmap
+	cmd.GidMappingsEnableSetgroups = true
+
+	logrus.Debugf("Running %#v in %#v", cmd.Cmd, cmd)
+	confwg.Add(1)
+	go func() {
+		_, conferr = io.Copy(pwriter, bytes.NewReader(config))
+		pwriter.Close()
+		confwg.Done()
+	}()
+	cmd.ExtraFiles = append([]*os.File{preader}, cmd.ExtraFiles...)
+	err = cmd.Run()
+	confwg.Wait()
+	if err == nil {
+		return conferr
+	}
+	return err
+}
+
+// main() for grandparent subprocess.  Its main job is to shuttle stdio back
+// and forth, managing a pseudo-terminal if we want one, for our child, the
+// parent subprocess.
+func runUsingChrootMain() {
+	var options runUsingChrootSubprocOptions
+
+	runtime.LockOSThread()
+
+	// Set logging.
+	if level := os.Getenv("LOGLEVEL"); level != "" {
+		if ll, err := strconv.Atoi(level); err == nil {
+			logrus.SetLevel(logrus.Level(ll))
+		}
+		os.Unsetenv("LOGLEVEL")
+	}
+
+	// Unpack our configuration.
+	confPipe := os.NewFile(3, "confpipe")
+	if confPipe == nil {
+		fmt.Fprintf(os.Stderr, "error reading options pipe\n")
+		os.Exit(1)
+	}
+	defer confPipe.Close()
+	if err := json.NewDecoder(confPipe).Decode(&options); err != nil {
+		fmt.Fprintf(os.Stderr, "error decoding options: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Prepare to shuttle stdio back and forth.
+	rootUid32, rootGid32, err := util.GetHostRootIDs(options.Spec)
+	if err != nil {
+		logrus.Errorf("error determining ownership for container stdio")
+		os.Exit(1)
+	}
+	rootUid := int(rootUid32)
+	rootGid := int(rootGid32)
+	relays := make(map[int]int)
+	closeOnceRunning := []*os.File{}
+	var ctty *os.File
+	var stdin io.Reader
+	var stdinCopy io.WriteCloser
+	var stdout io.Writer
+	var stderr io.Writer
+	fdDesc := make(map[int]string)
+	deferred := func() {}
+	if options.Spec.Process.Terminal {
+		// Create a pseudo-terminal -- open a copy of the master side.
+		ptyMasterFd, err := unix.Open("/dev/ptmx", os.O_RDWR, 0600)
+		if err != nil {
+			logrus.Errorf("error opening PTY master using /dev/ptmx: %v", err)
+			os.Exit(1)
+		}
+		// Set the kernel's lock to "unlocked".
+		locked := 0
+		if result, _, err := unix.Syscall(unix.SYS_IOCTL, uintptr(ptyMasterFd), unix.TIOCSPTLCK, uintptr(unsafe.Pointer(&locked))); int(result) == -1 {
+			logrus.Errorf("error locking PTY descriptor: %v", err)
+			os.Exit(1)
+		}
+		// Get a handle for the other end.
+		ptyFd, _, err := unix.Syscall(unix.SYS_IOCTL, uintptr(ptyMasterFd), unix.TIOCGPTPEER, unix.O_RDWR|unix.O_NOCTTY)
+		if int(ptyFd) == -1 {
+			if errno, isErrno := err.(syscall.Errno); !isErrno || (errno != syscall.EINVAL && errno != syscall.ENOTTY) {
+				logrus.Errorf("error getting PTY descriptor: %v", err)
+				os.Exit(1)
+			}
+			// EINVAL means the kernel's too old to understand TIOCGPTPEER.  Try TIOCGPTN.
+			ptyN, err := unix.IoctlGetInt(ptyMasterFd, unix.TIOCGPTN)
+			if err != nil {
+				logrus.Errorf("error getting PTY number: %v", err)
+				os.Exit(1)
+			}
+			ptyName := fmt.Sprintf("/dev/pts/%d", ptyN)
+			fd, err := unix.Open(ptyName, unix.O_RDWR|unix.O_NOCTTY, 0620)
+			if err != nil {
+				logrus.Errorf("error opening PTY %q: %v", ptyName, err)
+				os.Exit(1)
+			}
+			ptyFd = uintptr(fd)
+		}
+		// Make notes about what's going where.
+		relays[ptyMasterFd] = unix.Stdout
+		relays[unix.Stdin] = ptyMasterFd
+		fdDesc[ptyMasterFd] = "container terminal"
+		fdDesc[unix.Stdin] = "stdin"
+		fdDesc[unix.Stdout] = "stdout"
+		winsize := &unix.Winsize{}
+		// Set the pseudoterminal's size to the configured size, or our own.
+		if options.Spec.Process.ConsoleSize != nil {
+			// Use configured sizes.
+			winsize.Row = uint16(options.Spec.Process.ConsoleSize.Height)
+			winsize.Col = uint16(options.Spec.Process.ConsoleSize.Width)
+		} else {
+			if terminal.IsTerminal(unix.Stdin) {
+				// Use the size of our terminal.
+				winsize, err = unix.IoctlGetWinsize(unix.Stdin, unix.TIOCGWINSZ)
+				if err != nil {
+					logrus.Debugf("error reading current terminal's size")
+					winsize.Row = 0
+					winsize.Col = 0
+				}
+			}
+		}
+		if winsize.Row != 0 && winsize.Col != 0 {
+			if err = unix.IoctlSetWinsize(int(ptyFd), unix.TIOCSWINSZ, winsize); err != nil {
+				logrus.Warnf("error setting terminal size for pty")
+			}
+			// FIXME - if we're connected to a terminal, we should
+			// be passing the updated terminal size down when we
+			// receive a SIGWINCH.
+		}
+		// Open an *os.File object that we can pass to our child.
+		ctty = os.NewFile(ptyFd, "/dev/tty")
+		// Set ownership for the PTY.
+		if err = ctty.Chown(rootUid, rootGid); err != nil {
+			var cttyInfo unix.Stat_t
+			err2 := unix.Fstat(int(ptyFd), &cttyInfo)
+			from := ""
+			op := "setting"
+			if err2 == nil {
+				op = "changing"
+				from = fmt.Sprintf("from %d/%d ", cttyInfo.Uid, cttyInfo.Gid)
+			}
+			logrus.Warnf("error %s ownership of container PTY %sto %d/%d: %v", op, from, rootUid, rootGid, err)
+		}
+		// Set permissions on the PTY.
+		if err = ctty.Chmod(0620); err != nil {
+			logrus.Errorf("error setting permissions of container PTY: %v", err)
+			os.Exit(1)
+		}
+		// Make a note that our child (the parent subprocess) should
+		// have the PTY connected to its stdio, and that we should
+		// close it once it's running.
+		stdin = ctty
+		stdout = ctty
+		stderr = ctty
+		closeOnceRunning = append(closeOnceRunning, ctty)
+	} else {
+		// Create pipes for stdio.
+		stdinRead, stdinWrite, err := os.Pipe()
+		if err != nil {
+			logrus.Errorf("error opening pipe for stdin: %v", err)
+		}
+		stdoutRead, stdoutWrite, err := os.Pipe()
+		if err != nil {
+			logrus.Errorf("error opening pipe for stdout: %v", err)
+		}
+		stderrRead, stderrWrite, err := os.Pipe()
+		if err != nil {
+			logrus.Errorf("error opening pipe for stderr: %v", err)
+		}
+		// Make notes about what's going where.
+		relays[unix.Stdin] = int(stdinWrite.Fd())
+		relays[int(stdoutRead.Fd())] = unix.Stdout
+		relays[int(stderrRead.Fd())] = unix.Stderr
+		fdDesc[int(stdinWrite.Fd())] = "container stdin pipe"
+		fdDesc[int(stdoutRead.Fd())] = "container stdout pipe"
+		fdDesc[int(stderrRead.Fd())] = "container stderr pipe"
+		fdDesc[unix.Stdin] = "stdin"
+		fdDesc[unix.Stdout] = "stdout"
+		fdDesc[unix.Stderr] = "stderr"
+		// Set ownership for the pipes.
+		if err = stdinRead.Chown(rootUid, rootGid); err != nil {
+			logrus.Errorf("error setting ownership of container stdin pipe: %v", err)
+			os.Exit(1)
+		}
+		if err = stdoutWrite.Chown(rootUid, rootGid); err != nil {
+			logrus.Errorf("error setting ownership of container stdout pipe: %v", err)
+			os.Exit(1)
+		}
+		if err = stderrWrite.Chown(rootUid, rootGid); err != nil {
+			logrus.Errorf("error setting ownership of container stderr pipe: %v", err)
+			os.Exit(1)
+		}
+		// Make a note that our child (the parent subprocess) should
+		// have the pipes connected to its stdio, and that we should
+		// close its ends of them once it's running.
+		stdin = stdinRead
+		stdout = stdoutWrite
+		stderr = stderrWrite
+		closeOnceRunning = append(closeOnceRunning, stdinRead, stdoutWrite, stderrWrite)
+		stdinCopy = stdinWrite
+		defer stdoutRead.Close()
+		defer stderrRead.Close()
+	}
+	// A helper that returns false if err is an error that would cause us
+	// to give up.
+	logIfNotRetryable := func(err error, what string) (retry bool) {
+		if err == nil {
+			return true
+		}
+		if errno, isErrno := err.(syscall.Errno); isErrno {
+			switch errno {
+			case syscall.EINTR, syscall.EAGAIN:
+				return true
+			}
+		}
+		logrus.Error(what)
+		return false
+	}
+	for readFd := range relays {
+		if err := unix.SetNonblock(readFd, true); err != nil {
+			logrus.Errorf("error setting descriptor %d (%s) non-blocking: %v", readFd, fdDesc[readFd], err)
+			return
+		}
+	}
+	go func() {
+		buffers := make(map[int]*bytes.Buffer)
+		for _, writeFd := range relays {
+			buffers[writeFd] = new(bytes.Buffer)
+		}
+		pollTimeout := -1
+		for len(relays) > 0 {
+			fds := make([]unix.PollFd, 0, len(relays))
+			for fd := range relays {
+				fds = append(fds, unix.PollFd{Fd: int32(fd), Events: unix.POLLIN | unix.POLLHUP})
+			}
+			_, err := unix.Poll(fds, pollTimeout)
+			if !logIfNotRetryable(err, fmt.Sprintf("poll: %v", err)) {
+				return
+			}
+			removeFds := make(map[int]struct{})
+			for _, rfd := range fds {
+				if rfd.Revents&unix.POLLHUP == unix.POLLHUP {
+					removeFds[int(rfd.Fd)] = struct{}{}
+				}
+				if rfd.Revents&unix.POLLNVAL == unix.POLLNVAL {
+					logrus.Debugf("error polling descriptor %s: closed?", fdDesc[int(rfd.Fd)])
+					removeFds[int(rfd.Fd)] = struct{}{}
+				}
+				if rfd.Revents&unix.POLLIN == 0 {
+					continue
+				}
+				b := make([]byte, 8192)
+				nread, err := unix.Read(int(rfd.Fd), b)
+				logIfNotRetryable(err, fmt.Sprintf("read %s: %v", fdDesc[int(rfd.Fd)], err))
+				if nread > 0 {
+					if wfd, ok := relays[int(rfd.Fd)]; ok {
+						nwritten, err := buffers[wfd].Write(b[:nread])
+						if err != nil {
+							logrus.Debugf("buffer: %v", err)
+							continue
+						}
+						if nwritten != nread {
+							logrus.Debugf("buffer: expected to buffer %d bytes, wrote %d", nread, nwritten)
+							continue
+						}
+					}
+				}
+				if nread == 0 {
+					removeFds[int(rfd.Fd)] = struct{}{}
+				}
+			}
+			pollTimeout = -1
+			for wfd, buffer := range buffers {
+				if buffer.Len() > 0 {
+					nwritten, err := unix.Write(wfd, buffer.Bytes())
+					logIfNotRetryable(err, fmt.Sprintf("write %s: %v", fdDesc[wfd], err))
+					if nwritten >= 0 {
+						_ = buffer.Next(nwritten)
+					}
+				}
+				if buffer.Len() > 0 {
+					pollTimeout = 100
+				}
+			}
+			for rfd := range removeFds {
+				if !options.Spec.Process.Terminal && rfd == unix.Stdin {
+					stdinCopy.Close()
+				}
+				delete(relays, rfd)
+			}
+		}
+	}()
+
+	// Set up mounts and namespaces, and run the parent subprocess.
+	status, err := runUsingChroot(options.Spec, options.BundlePath, ctty, stdin, stdout, stderr, closeOnceRunning)
+	deferred()
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error running subprocess: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Pass the process's exit status back to the caller by exiting with the same status.
+	if status.Exited() {
+		if status.ExitStatus() != 0 {
+			fmt.Fprintf(os.Stderr, "subprocess exited with status %d\n", status.ExitStatus())
+		}
+		os.Exit(status.ExitStatus())
+	} else if status.Signaled() {
+		fmt.Fprintf(os.Stderr, "subprocess exited on %s\n", status.Signal())
+		os.Exit(1)
+	}
+}
+
+// runUsingChroot, still in the grandparent process, sets up various bind
+// mounts and then runs the parent process in its own user namespace with the
+// necessary ID mappings.
+func runUsingChroot(spec *specs.Spec, bundlePath string, ctty *os.File, stdin io.Reader, stdout, stderr io.Writer, closeOnceRunning []*os.File) (wstatus unix.WaitStatus, err error) {
+	var confwg sync.WaitGroup
+
+	// Create a new mount namespace for ourselves and bind mount everything to a new location.
+	undoIntermediates, err := bind.SetupIntermediateMountNamespace(spec, bundlePath)
+	if err != nil {
+		return 1, err
+	}
+	defer func() {
+		undoIntermediates()
+	}()
+
+	// Bind mount in our filesystems.
+	undoChroots, err := setupChrootBindMounts(spec, bundlePath)
+	if err != nil {
+		return 1, err
+	}
+	defer func() {
+		undoChroots()
+	}()
+
+	// Create a pipe for passing configuration down to the next process.
+	preader, pwriter, err := os.Pipe()
+	if err != nil {
+		return 1, errors.Wrapf(err, "error creating configuration pipe")
+	}
+	config, conferr := json.Marshal(runUsingChrootExecSubprocOptions{
+		Spec:       spec,
+		BundlePath: bundlePath,
+	})
+	if conferr != nil {
+		fmt.Fprintf(os.Stderr, "error re-encoding configuration for %q", runUsingChrootExecCommand)
+		os.Exit(1)
+	}
+
+	// Apologize for the namespace configuration that we're about to ignore.
+	logNamespaceDiagnostics(spec)
+
+	// If we have configured ID mappings, set them here so that they can apply to the child.
+	hostUidmap, hostGidmap, err := util.GetHostIDMappings("")
+	if err != nil {
+		return 1, err
+	}
+	uidmap, gidmap := spec.Linux.UIDMappings, spec.Linux.GIDMappings
+	if len(uidmap) == 0 {
+		// No UID mappings are configured for the container.  Borrow our parent's mappings.
+		uidmap = append([]specs.LinuxIDMapping{}, hostUidmap...)
+		for i := range uidmap {
+			uidmap[i].HostID = uidmap[i].ContainerID
+		}
+	}
+	if len(gidmap) == 0 {
+		// No GID mappings are configured for the container.  Borrow our parent's mappings.
+		gidmap = append([]specs.LinuxIDMapping{}, hostGidmap...)
+		for i := range gidmap {
+			gidmap[i].HostID = gidmap[i].ContainerID
+		}
+	}
+
+	// Start the parent subprocess.
+	cmd := unshare.Command(append([]string{runUsingChrootExecCommand}, spec.Process.Args...)...)
+	cmd.Stdin, cmd.Stdout, cmd.Stderr = stdin, stdout, stderr
+	cmd.Dir = "/"
+	cmd.Env = append([]string{fmt.Sprintf("LOGLEVEL=%d", logrus.GetLevel())}, os.Environ()...)
+	cmd.UnshareFlags = syscall.CLONE_NEWUSER | syscall.CLONE_NEWUTS | syscall.CLONE_NEWNS
+	cmd.UidMappings = uidmap
+	cmd.GidMappings = gidmap
+	cmd.GidMappingsEnableSetgroups = true
+	if ctty != nil {
+		cmd.Setsid = true
+		cmd.Ctty = ctty
+	}
+	if spec.Process.OOMScoreAdj != nil {
+		cmd.OOMScoreAdj = *spec.Process.OOMScoreAdj
+	}
+	cmd.ExtraFiles = append([]*os.File{preader}, cmd.ExtraFiles...)
+	cmd.Hook = func(int) error {
+		for _, f := range closeOnceRunning {
+			f.Close()
+		}
+		return nil
+	}
+
+	logrus.Debugf("Running %#v in %#v", cmd.Cmd, cmd)
+	confwg.Add(1)
+	go func() {
+		_, conferr = io.Copy(pwriter, bytes.NewReader(config))
+		pwriter.Close()
+		confwg.Done()
+	}()
+	err = cmd.Run()
+	confwg.Wait()
+	if err != nil {
+		if exitError, ok := err.(*exec.ExitError); ok {
+			if waitStatus, ok := exitError.ProcessState.Sys().(syscall.WaitStatus); ok {
+				if waitStatus.Exited() {
+					if waitStatus.ExitStatus() != 0 {
+						fmt.Fprintf(os.Stderr, "subprocess exited with status %d\n", waitStatus.ExitStatus())
+					}
+					os.Exit(waitStatus.ExitStatus())
+				} else if waitStatus.Signaled() {
+					fmt.Fprintf(os.Stderr, "subprocess exited on %s\n", waitStatus.Signal())
+					os.Exit(1)
+				}
+			}
+		}
+		fmt.Fprintf(os.Stderr, "process exited with error: %v", err)
+		os.Exit(1)
+	}
+
+	return 0, nil
+}
+
+// main() for parent subprocess.  Its main job is to try to make our
+// environment look like the one described by the runtime configuration blob,
+// and then launch the intended command as a child, since we can't exec()
+// directly.
+func runUsingChrootExecMain() {
+	args := os.Args[1:]
+	var options runUsingChrootExecSubprocOptions
+	var err error
+
+	runtime.LockOSThread()
+
+	// Set logging.
+	if level := os.Getenv("LOGLEVEL"); level != "" {
+		if ll, err := strconv.Atoi(level); err == nil {
+			logrus.SetLevel(logrus.Level(ll))
+		}
+		os.Unsetenv("LOGLEVEL")
+	}
+
+	// Unpack our configuration.
+	confPipe := os.NewFile(3, "confpipe")
+	if confPipe == nil {
+		fmt.Fprintf(os.Stderr, "error reading options pipe\n")
+		os.Exit(1)
+	}
+	defer confPipe.Close()
+	if err := json.NewDecoder(confPipe).Decode(&options); err != nil {
+		fmt.Fprintf(os.Stderr, "error decoding options: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Set the hostname.  We're already in a distinct UTS namespace and are admins in the user
+	// namespace which created it, so we shouldn't get a permissions error, but seccomp policy
+	// might deny our attempt to call sethostname() anyway, so log a debug message for that.
+	if options.Spec.Hostname != "" {
+		if err := unix.Sethostname([]byte(options.Spec.Hostname)); err != nil {
+			logrus.Debugf("failed to set hostname %q for process: %v", options.Spec.Hostname, err)
+		}
+	}
+
+	// not doing because it's still shared: creating devices
+	// not doing because it's not applicable: setting annotations
+	// not doing because it's still shared: setting sysctl settings
+	// not doing because cgroupfs is read only: configuring control groups
+	// -> this means we can use the freezer to make sure there aren't any lingering processes
+	// -> this means we ignore cgroups-based controls
+	// not doing because we don't set any in the config: running hooks
+	// not doing because we don't set it in the config: setting rootfs read-only
+	// not doing because we don't set it in the config: setting rootfs propagation
+	logrus.Debugf("setting apparmor profile")
+	if err = setApparmorProfile(options.Spec); err != nil {
+		fmt.Fprintf(os.Stderr, "error setting apparmor profile for process: %v\n", err)
+		os.Exit(1)
+	}
+	if err = setSelinuxLabel(options.Spec); err != nil {
+		fmt.Fprintf(os.Stderr, "error setting SELinux label for process: %v\n", err)
+		os.Exit(1)
+	}
+	logrus.Debugf("setting capabilities")
+	if err := setCapabilities(options.Spec); err != nil {
+		fmt.Fprintf(os.Stderr, "error setting capabilities for process %v\n", err)
+		os.Exit(1)
+	}
+	if err = setSeccomp(options.Spec); err != nil {
+		fmt.Fprintf(os.Stderr, "error setting seccomp filter for process: %v\n", err)
+		os.Exit(1)
+	}
+	logrus.Debugf("setting resource limits")
+	if err = setRlimits(options.Spec, false, false); err != nil {
+		fmt.Fprintf(os.Stderr, "error setting process resource limits for process: %v\n", err)
+		os.Exit(1)
+	}
+
+	// Try to chroot into the root.
+	if err := unix.Chroot(options.Spec.Root.Path); err != nil {
+		fmt.Fprintf(os.Stderr, "error chroot()ing into directory %q: %v\n", options.Spec.Root.Path, err)
+		os.Exit(1)
+	}
+	cwd := options.Spec.Process.Cwd
+	if !filepath.IsAbs(cwd) {
+		cwd = "/" + cwd
+	}
+	if err := unix.Chdir(cwd); err != nil {
+		fmt.Fprintf(os.Stderr, "error chdir()ing into directory %q: %v\n", cwd, err)
+		os.Exit(1)
+	}
+	logrus.Debugf("chrooted into %q, changed working directory to %q", options.Spec.Root.Path, cwd)
+
+	// Drop privileges.
+	user := options.Spec.Process.User
+	if len(user.AdditionalGids) > 0 {
+		gids := make([]int, len(user.AdditionalGids))
+		for i := range user.AdditionalGids {
+			gids[i] = int(user.AdditionalGids[i])
+		}
+		logrus.Debugf("setting supplemental groups")
+		if err = syscall.Setgroups(gids); err != nil {
+			fmt.Fprintf(os.Stderr, "error setting supplemental groups list: %v", err)
+			os.Exit(1)
+		}
+	} else {
+		logrus.Debugf("clearing supplemental groups")
+		if err = syscall.Setgroups([]int{}); err != nil {
+			fmt.Fprintf(os.Stderr, "error clearing supplemental groups list: %v", err)
+			os.Exit(1)
+		}
+	}
+	logrus.Debugf("setting gid")
+	if err = syscall.Setresgid(int(user.GID), int(user.GID), int(user.GID)); err != nil {
+		fmt.Fprintf(os.Stderr, "error setting GID: %v", err)
+		os.Exit(1)
+	}
+	logrus.Debugf("setting uid")
+	if err = syscall.Setresuid(int(user.UID), int(user.UID), int(user.UID)); err != nil {
+		fmt.Fprintf(os.Stderr, "error setting UID: %v", err)
+		os.Exit(1)
+	}
+
+	// Actually run the specified command.
+	cmd := exec.Command(args[0], args[1:]...)
+	cmd.Env = options.Spec.Process.Env
+	cmd.Stdin, cmd.Stdout, cmd.Stderr = os.Stdin, os.Stdout, os.Stderr
+	cmd.Dir = cwd
+	logrus.Debugf("Running %#v (PATH = %q)", cmd, os.Getenv("PATH"))
+	if err = cmd.Run(); err != nil {
+		if exitError, ok := err.(*exec.ExitError); ok {
+			if waitStatus, ok := exitError.ProcessState.Sys().(syscall.WaitStatus); ok {
+				if waitStatus.Exited() {
+					if waitStatus.ExitStatus() != 0 {
+						fmt.Fprintf(os.Stderr, "subprocess exited with status %d\n", waitStatus.ExitStatus())
+					}
+					os.Exit(waitStatus.ExitStatus())
+				} else if waitStatus.Signaled() {
+					fmt.Fprintf(os.Stderr, "subprocess exited on %s\n", waitStatus.Signal())
+					os.Exit(1)
+				}
+			}
+		}
+		fmt.Fprintf(os.Stderr, "process exited with error: %v", err)
+		os.Exit(1)
+	}
+}
+
+// logNamespaceDiagnostics knows which namespaces we want to create.
+// Output debug messages when that differs from what we're being asked to do.
+func logNamespaceDiagnostics(spec *specs.Spec) {
+	sawMountNS := false
+	sawUserNS := false
+	sawUTSNS := false
+	for _, ns := range spec.Linux.Namespaces {
+		switch ns.Type {
+		case specs.CgroupNamespace:
+			if ns.Path != "" {
+				logrus.Debugf("unable to join cgroup namespace, sorry about that")
+			} else {
+				logrus.Debugf("unable to create cgroup namespace, sorry about that")
+			}
+		case specs.IPCNamespace:
+			if ns.Path != "" {
+				logrus.Debugf("unable to join IPC namespace, sorry about that")
+			} else {
+				logrus.Debugf("unable to create IPC namespace, sorry about that")
+			}
+		case specs.MountNamespace:
+			if ns.Path != "" {
+				logrus.Debugf("unable to join mount namespace %q, creating a new one", ns.Path)
+			}
+			sawMountNS = true
+		case specs.NetworkNamespace:
+			if ns.Path != "" {
+				logrus.Debugf("unable to join network namespace, sorry about that")
+			} else {
+				logrus.Debugf("unable to create network namespace, sorry about that")
+			}
+		case specs.PIDNamespace:
+			if ns.Path != "" {
+				logrus.Debugf("unable to join PID namespace, sorry about that")
+			} else {
+				logrus.Debugf("unable to create PID namespace, sorry about that")
+			}
+		case specs.UserNamespace:
+			if ns.Path != "" {
+				logrus.Debugf("unable to join user namespace %q, creating a new one", ns.Path)
+			}
+			sawUserNS = true
+		case specs.UTSNamespace:
+			if ns.Path != "" {
+				logrus.Debugf("unable to join UTS namespace %q, creating a new one", ns.Path)
+			}
+			sawUTSNS = true
+		}
+	}
+	if !sawMountNS {
+		logrus.Debugf("mount namespace not requested, but creating a new one anyway")
+	}
+	if !sawUserNS {
+		logrus.Debugf("user namespace not requested, but creating a new one anyway")
+	}
+	if !sawUTSNS {
+		logrus.Debugf("UTS namespace not requested, but creating a new one anyway")
+	}
+}
+
+// setApparmorProfile sets the apparmor profile for ourselves, and hopefully any child processes that we'll start.
+func setApparmorProfile(spec *specs.Spec) error {
+	if !apparmor.IsEnabled() || spec.Process.ApparmorProfile == "" {
+		return nil
+	}
+	if err := apparmor.ApplyProfile(spec.Process.ApparmorProfile); err != nil {
+		return errors.Wrapf(err, "error setting apparmor profile to %q", spec.Process.ApparmorProfile)
+	}
+	return nil
+}
+
+// setCapabilities sets capabilities for ourselves, to be more or less inherited by any processes that we'll start.
+func setCapabilities(spec *specs.Spec) error {
+	caps, err := capability.NewPid(0)
+	if err != nil {
+		return errors.Wrapf(err, "error reading capabilities of current process")
+	}
+	capMap := map[capability.CapType][]string{
+		capability.BOUNDING:    spec.Process.Capabilities.Bounding,
+		capability.EFFECTIVE:   spec.Process.Capabilities.Effective,
+		capability.INHERITABLE: spec.Process.Capabilities.Inheritable,
+		capability.PERMITTED:   spec.Process.Capabilities.Permitted,
+		capability.AMBIENT:     spec.Process.Capabilities.Ambient,
+	}
+	knownCaps := capability.List()
+	for capType, capList := range capMap {
+		caps.Clear(capType)
+		for _, capToSet := range capList {
+			cap := capability.CAP_LAST_CAP
+			for _, c := range knownCaps {
+				if strings.EqualFold("CAP_"+c.String(), capToSet) {
+					cap = c
+					break
+				}
+			}
+			if cap == capability.CAP_LAST_CAP {
+				return errors.Errorf("error mapping capability %q to a number", capToSet)
+			}
+			caps.Set(capType, cap)
+		}
+	}
+	for capType := range capMap {
+		if err = caps.Apply(capType); err != nil {
+			return errors.Wrapf(err, "error setting %s capabilities to %#v", capType.String(), capMap[capType])
+		}
+	}
+	return nil
+}
+
+// parses the resource limits for ourselves and any processes that
+// we'll start into a format that's more in line with the kernel APIs
+func parseRlimits(spec *specs.Spec) (map[int]unix.Rlimit, error) {
+	if spec.Process == nil {
+		return nil, nil
+	}
+	parsed := make(map[int]unix.Rlimit)
+	for _, limit := range spec.Process.Rlimits {
+		resource, recognized := rlimitsMap[strings.ToUpper(limit.Type)]
+		if !recognized {
+			return nil, errors.Errorf("error parsing limit type %q", limit.Type)
+		}
+		parsed[resource] = unix.Rlimit{Cur: limit.Soft, Max: limit.Hard}
+	}
+	return parsed, nil
+}
+
+// setRlimits sets any resource limits that we want to apply to processes that
+// we'll start.
+func setRlimits(spec *specs.Spec, onlyLower, onlyRaise bool) error {
+	limits, err := parseRlimits(spec)
+	if err != nil {
+		return err
+	}
+	for resource, desired := range limits {
+		var current unix.Rlimit
+		if err := unix.Getrlimit(resource, &current); err != nil {
+			return errors.Wrapf(err, "error reading %q limit", rlimitsReverseMap[resource])
+		}
+		if desired.Max > current.Max && onlyLower {
+			// this would raise a hard limit, and we're only here to lower them
+			continue
+		}
+		if desired.Max < current.Max && onlyRaise {
+			// this would lower a hard limit, and we're only here to raise them
+			continue
+		}
+		if err := unix.Setrlimit(resource, &desired); err != nil {
+			return errors.Wrapf(err, "error setting %q limit to soft=%d,hard=%d (was soft=%d,hard=%d)", rlimitsReverseMap[resource], desired.Cur, desired.Max, current.Cur, current.Max)
+		}
+	}
+	return nil
+}
+
+// setupChrootBindMounts actually bind mounts things under the rootfs, and returns a
+// callback that will clean up its work.
+func setupChrootBindMounts(spec *specs.Spec, bundlePath string) (undoBinds func() error, err error) {
+	var fs unix.Statfs_t
+	removes := []string{}
+	undoBinds = func() error {
+		if err2 := bind.UnmountMountpoints(spec.Root.Path, removes); err2 != nil {
+			logrus.Warnf("pkg/chroot: error unmounting %q: %v", spec.Root.Path, err2)
+			if err == nil {
+				err = err2
+			}
+		}
+		return err
+	}
+
+	// Now bind mount all of those things to be under the rootfs's location in this
+	// mount namespace.
+	commonFlags := uintptr(unix.MS_BIND | unix.MS_REC | unix.MS_PRIVATE)
+	bindFlags := commonFlags | unix.MS_NODEV
+	devFlags := commonFlags | unix.MS_NOEXEC | unix.MS_NOSUID | unix.MS_RDONLY
+	procFlags := devFlags | unix.MS_NODEV
+	sysFlags := devFlags | unix.MS_NODEV | unix.MS_RDONLY
+
+	// Bind /dev read-only.
+	subDev := filepath.Join(spec.Root.Path, "/dev")
+	if err := unix.Mount("/dev", subDev, "bind", devFlags, ""); err != nil {
+		if os.IsNotExist(err) {
+			err = os.Mkdir(subDev, 0700)
+			if err == nil {
+				err = unix.Mount("/dev", subDev, "bind", devFlags, "")
+			}
+		}
+		if err != nil {
+			return undoBinds, errors.Wrapf(err, "error bind mounting /dev from host into mount namespace")
+		}
+	}
+	// Make sure it's read-only.
+	if err = unix.Statfs(subDev, &fs); err != nil {
+		return undoBinds, errors.Wrapf(err, "error checking if directory %q was bound read-only", subDev)
+	}
+	if fs.Flags&unix.ST_RDONLY == 0 {
+		if err := unix.Mount(subDev, subDev, "bind", devFlags|unix.MS_REMOUNT, ""); err != nil {
+			return undoBinds, errors.Wrapf(err, "error remounting /dev in mount namespace read-only")
+		}
+	}
+	logrus.Debugf("bind mounted %q to %q", "/dev", filepath.Join(spec.Root.Path, "/dev"))
+
+	// Bind /proc read-write.
+	subProc := filepath.Join(spec.Root.Path, "/proc")
+	if err := unix.Mount("/proc", subProc, "bind", procFlags, ""); err != nil {
+		if os.IsNotExist(err) {
+			err = os.Mkdir(subProc, 0700)
+			if err == nil {
+				err = unix.Mount("/proc", subProc, "bind", procFlags, "")
+			}
+		}
+		if err != nil {
+			return undoBinds, errors.Wrapf(err, "error bind mounting /proc from host into mount namespace")
+		}
+	}
+	logrus.Debugf("bind mounted %q to %q", "/proc", filepath.Join(spec.Root.Path, "/proc"))
+
+	// Bind /sys read-only.
+	subSys := filepath.Join(spec.Root.Path, "/sys")
+	if err := unix.Mount("/sys", subSys, "bind", sysFlags, ""); err != nil {
+		if os.IsNotExist(err) {
+			err = os.Mkdir(subSys, 0700)
+			if err == nil {
+				err = unix.Mount("/sys", subSys, "bind", sysFlags, "")
+			}
+		}
+		if err != nil {
+			return undoBinds, errors.Wrapf(err, "error bind mounting /sys from host into mount namespace")
+		}
+	}
+	// Make sure it's read-only.
+	if err = unix.Statfs(subSys, &fs); err != nil {
+		return undoBinds, errors.Wrapf(err, "error checking if directory %q was bound read-only", subSys)
+	}
+	if fs.Flags&unix.ST_RDONLY == 0 {
+		if err := unix.Mount(subSys, subSys, "bind", sysFlags|unix.MS_REMOUNT, ""); err != nil {
+			return undoBinds, errors.Wrapf(err, "error remounting /sys in mount namespace read-only")
+		}
+	}
+	logrus.Debugf("bind mounted %q to %q", "/sys", filepath.Join(spec.Root.Path, "/sys"))
+
+	// Add /sys/fs/selinux to the set of masked paths, to ensure that we don't have processes
+	// attempting to interact with labeling, when they aren't allowed to do so.
+	spec.Linux.MaskedPaths = append(spec.Linux.MaskedPaths, "/sys/fs/selinux")
+	// Add /sys/fs/cgroup to the set of masked paths, to ensure that we don't have processes
+	// attempting to mess with cgroup configuration, when they aren't allowed to do so.
+	spec.Linux.MaskedPaths = append(spec.Linux.MaskedPaths, "/sys/fs/cgroup")
+
+	// Bind mount in everything we've been asked to mount.
+	for _, m := range spec.Mounts {
+		// Skip anything that we just mounted.
+		switch m.Destination {
+		case "/dev", "/proc", "/sys":
+			logrus.Debugf("already bind mounted %q on %q", m.Destination, filepath.Join(spec.Root.Path, m.Destination))
+			continue
+		default:
+			if strings.HasPrefix(m.Destination, "/dev/") {
+				continue
+			}
+			if strings.HasPrefix(m.Destination, "/proc/") {
+				continue
+			}
+			if strings.HasPrefix(m.Destination, "/sys/") {
+				continue
+			}
+		}
+		// Skip anything that isn't a bind or tmpfs mount.
+		if m.Type != "bind" && m.Type != "tmpfs" {
+			logrus.Debugf("skipping mount of type %q on %q", m.Type, m.Destination)
+			continue
+		}
+		// If the target is there, we can just mount it.
+		var srcinfo os.FileInfo
+		switch m.Type {
+		case "bind":
+			srcinfo, err = os.Stat(m.Source)
+			if err != nil {
+				return undoBinds, errors.Wrapf(err, "error examining %q for mounting in mount namespace", m.Source)
+			}
+		case "tmpfs":
+			srcinfo, err = os.Stat("/")
+			if err != nil {
+				return undoBinds, errors.Wrapf(err, "error examining / to use as a template for a tmpfs")
+			}
+		}
+		target := filepath.Join(spec.Root.Path, m.Destination)
+		if _, err := os.Stat(target); err != nil {
+			// If the target can't be stat()ted, check the error.
+			if !os.IsNotExist(err) {
+				return undoBinds, errors.Wrapf(err, "error examining %q for mounting in mount namespace", target)
+			}
+			// The target isn't there yet, so create it, and make a
+			// note to remove it later.
+			if srcinfo.IsDir() {
+				if err = os.Mkdir(target, 0111); err != nil {
+					return undoBinds, errors.Wrapf(err, "error creating mountpoint %q in mount namespace", target)
+				}
+				removes = append(removes, target)
+			} else {
+				var file *os.File
+				if file, err = os.OpenFile(target, os.O_WRONLY|os.O_CREATE, 0); err != nil {
+					return undoBinds, errors.Wrapf(err, "error creating mountpoint %q in mount namespace", target)
+				}
+				file.Close()
+				removes = append(removes, target)
+			}
+		}
+		requestFlags := bindFlags
+		expectedFlags := uintptr(0)
+		if util.StringInSlice("nodev", m.Options) {
+			requestFlags |= unix.MS_NODEV
+			expectedFlags |= unix.ST_NODEV
+		}
+		if util.StringInSlice("noexec", m.Options) {
+			requestFlags |= unix.MS_NOEXEC
+			expectedFlags |= unix.ST_NOEXEC
+		}
+		if util.StringInSlice("nosuid", m.Options) {
+			requestFlags |= unix.MS_NOSUID
+			expectedFlags |= unix.ST_NOSUID
+		}
+		if util.StringInSlice("ro", m.Options) {
+			requestFlags |= unix.MS_RDONLY
+			expectedFlags |= unix.ST_RDONLY
+		}
+		switch m.Type {
+		case "bind":
+			// Do the bind mount.
+			if err := unix.Mount(m.Source, target, "", requestFlags, ""); err != nil {
+				return undoBinds, errors.Wrapf(err, "error bind mounting %q from host to %q in mount namespace (%q)", m.Source, m.Destination, target)
+			}
+			logrus.Debugf("bind mounted %q to %q", m.Source, target)
+		case "tmpfs":
+			// Mount a tmpfs.
+			if err := mount.Mount(m.Source, target, m.Type, strings.Join(append(m.Options, "private"), ",")); err != nil {
+				return undoBinds, errors.Wrapf(err, "error mounting tmpfs to %q in mount namespace (%q, %q)", m.Destination, target, strings.Join(m.Options, ","))
+			}
+			logrus.Debugf("mounted a tmpfs to %q", target)
+		}
+		if err = unix.Statfs(target, &fs); err != nil {
+			return undoBinds, errors.Wrapf(err, "error checking if directory %q was bound read-only", subSys)
+		}
+		if uintptr(fs.Flags)&expectedFlags != expectedFlags {
+			if err := unix.Mount(target, target, "bind", requestFlags|unix.MS_REMOUNT, ""); err != nil {
+				return undoBinds, errors.Wrapf(err, "error remounting %q in mount namespace with expected flags")
+			}
+		}
+	}
+
+	// Set up any read-only paths that we need to.  If we're running inside
+	// of a container, some of these locations will already be read-only.
+	for _, roPath := range spec.Linux.ReadonlyPaths {
+		r := filepath.Join(spec.Root.Path, roPath)
+		target, err := filepath.EvalSymlinks(r)
+		if err != nil {
+			if os.IsNotExist(err) {
+				// No target, no problem.
+				continue
+			}
+			return undoBinds, errors.Wrapf(err, "error checking %q for symlinks before marking it read-only", r)
+		}
+		// Check if the location is already read-only.
+		var fs unix.Statfs_t
+		if err = unix.Statfs(target, &fs); err != nil {
+			if os.IsNotExist(err) {
+				// No target, no problem.
+				continue
+			}
+			return undoBinds, errors.Wrapf(err, "error checking if directory %q is already read-only", target)
+		}
+		if fs.Flags&unix.ST_RDONLY != 0 {
+			continue
+		}
+		// Mount the location over itself, so that we can remount it as read-only.
+		roFlags := uintptr(unix.MS_NODEV | unix.MS_NOEXEC | unix.MS_NOSUID | unix.MS_RDONLY)
+		if err := unix.Mount(target, target, "", roFlags|unix.MS_BIND|unix.MS_REC, ""); err != nil {
+			if os.IsNotExist(err) {
+				// No target, no problem.
+				continue
+			}
+			return undoBinds, errors.Wrapf(err, "error bind mounting %q onto itself in preparation for making it read-only", target)
+		}
+		// Remount the location read-only.
+		if err = unix.Statfs(target, &fs); err != nil {
+			return undoBinds, errors.Wrapf(err, "error checking if directory %q was bound read-only", target)
+		}
+		if fs.Flags&unix.ST_RDONLY == 0 {
+			if err := unix.Mount(target, target, "", roFlags|unix.MS_BIND|unix.MS_REMOUNT, ""); err != nil {
+				return undoBinds, errors.Wrapf(err, "error remounting %q in mount namespace read-only", target)
+			}
+		}
+		// Check again.
+		if err = unix.Statfs(target, &fs); err != nil {
+			return undoBinds, errors.Wrapf(err, "error checking if directory %q was remounted read-only", target)
+		}
+		if fs.Flags&unix.ST_RDONLY == 0 {
+			return undoBinds, errors.Wrapf(err, "error verifying that %q in mount namespace was remounted read-only", target)
+		}
+	}
+
+	// Set up any masked paths that we need to.  If we're running inside of
+	// a container, some of these locations will already be read-only tmpfs
+	// filesystems or bind mounted to os.DevNull.  If we're not running
+	// inside of a container, and nobody else has done that, we'll do it.
+	for _, masked := range spec.Linux.MaskedPaths {
+		t := filepath.Join(spec.Root.Path, masked)
+		target, err := filepath.EvalSymlinks(t)
+		if err != nil {
+			target = t
+		}
+		// Get some info about the null device.
+		nullinfo, err := os.Stat(os.DevNull)
+		if err != nil {
+			return undoBinds, errors.Wrapf(err, "error examining %q for masking in mount namespace", os.DevNull)
+		}
+		// Get some info about the target.
+		targetinfo, err := os.Stat(target)
+		if err != nil {
+			if os.IsNotExist(err) {
+				// No target, no problem.
+				continue
+			}
+			return undoBinds, errors.Wrapf(err, "error examining %q for masking in mount namespace", target)
+		}
+		if targetinfo.IsDir() {
+			// The target's a directory.  Check if it's a read-only filesystem.
+			var statfs unix.Statfs_t
+			if err = unix.Statfs(target, &statfs); err != nil {
+				return undoBinds, errors.Wrapf(err, "error checking if directory %q is a mountpoint", target)
+			}
+			isReadOnly := statfs.Flags&unix.MS_RDONLY != 0
+			// Check if any of the IDs we're mapping could read it.
+			isAccessible := true
+			var stat unix.Stat_t
+			if err = unix.Stat(target, &stat); err != nil {
+				return undoBinds, errors.Wrapf(err, "error checking permissions on directory %q", target)
+			}
+			isAccessible = false
+			if stat.Mode&unix.S_IROTH|unix.S_IXOTH != 0 {
+				isAccessible = true
+			}
+			if !isAccessible && stat.Mode&unix.S_IROTH|unix.S_IXOTH != 0 {
+				if len(spec.Linux.GIDMappings) > 0 {
+					for _, mapping := range spec.Linux.GIDMappings {
+						if stat.Gid >= mapping.ContainerID && stat.Gid < mapping.ContainerID+mapping.Size {
+							isAccessible = true
+							break
+						}
+					}
+				}
+			}
+			if !isAccessible && stat.Mode&unix.S_IRUSR|unix.S_IXUSR != 0 {
+				if len(spec.Linux.UIDMappings) > 0 {
+					for _, mapping := range spec.Linux.UIDMappings {
+						if stat.Uid >= mapping.ContainerID && stat.Uid < mapping.ContainerID+mapping.Size {
+							isAccessible = true
+							break
+						}
+					}
+				}
+			}
+			// Check if it's empty.
+			hasContent := false
+			directory, err := os.Open(target)
+			if err != nil {
+				if !os.IsPermission(err) {
+					return undoBinds, errors.Wrapf(err, "error opening directory %q", target)
+				}
+			} else {
+				names, err := directory.Readdirnames(0)
+				directory.Close()
+				if err != nil {
+					return undoBinds, errors.Wrapf(err, "error reading contents of directory %q", target)
+				}
+				hasContent = false
+				for _, name := range names {
+					switch name {
+					case ".", "..":
+						continue
+					default:
+						hasContent = true
+					}
+					if hasContent {
+						break
+					}
+				}
+			}
+			// The target's a directory, so mount a read-only tmpfs on it.
+			roFlags := uintptr(syscall.MS_NOSUID | syscall.MS_NODEV | syscall.MS_NOEXEC | syscall.MS_RDONLY)
+			if !isReadOnly || (hasContent && isAccessible) {
+				if err = unix.Mount("none", target, "tmpfs", roFlags, "size=0"); err != nil {
+					return undoBinds, errors.Wrapf(err, "error masking directory %q in mount namespace", target)
+				}
+				if err = unix.Statfs(target, &fs); err != nil {
+					return undoBinds, errors.Wrapf(err, "error checking if directory %q was mounted read-only in mount namespace", target)
+				}
+				if fs.Flags&unix.ST_RDONLY == 0 {
+					if err = unix.Mount(target, target, "", roFlags|syscall.MS_REMOUNT, ""); err != nil {
+						return undoBinds, errors.Wrapf(err, "error making sure directory %q in mount namespace is read only", target)
+					}
+				}
+			}
+		} else {
+			// The target's not a directory, so bind mount os.DevNull over it, unless it's already os.DevNull.
+			if !os.SameFile(nullinfo, targetinfo) {
+				if err = unix.Mount(os.DevNull, target, "", uintptr(syscall.MS_BIND|syscall.MS_RDONLY|syscall.MS_PRIVATE), ""); err != nil {
+					return undoBinds, errors.Wrapf(err, "error masking non-directory %q in mount namespace", target)
+				}
+			}
+		}
+	}
+	return undoBinds, nil
+}
diff --git a/vendor/github.com/projectatomic/buildah/chroot/seccomp.go b/vendor/github.com/projectatomic/buildah/chroot/seccomp.go
new file mode 100644
index 000000000..d5c5842d4
--- /dev/null
+++ b/vendor/github.com/projectatomic/buildah/chroot/seccomp.go
@@ -0,0 +1,142 @@
+// +build linux,seccomp
+
+package chroot
+
+import (
+	"github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+	libseccomp "github.com/seccomp/libseccomp-golang"
+	"github.com/sirupsen/logrus"
+)
+
+// setSeccomp sets the seccomp filter for ourselves and any processes that we'll start.
+func setSeccomp(spec *specs.Spec) error {
+	logrus.Debugf("setting seccomp configuration")
+	if spec.Linux.Seccomp == nil {
+		return nil
+	}
+	mapAction := func(specAction specs.LinuxSeccompAction) libseccomp.ScmpAction {
+		switch specAction {
+		case specs.ActKill:
+			return libseccomp.ActKill
+		case specs.ActTrap:
+			return libseccomp.ActTrap
+		case specs.ActErrno:
+			return libseccomp.ActErrno
+		case specs.ActTrace:
+			return libseccomp.ActTrace
+		case specs.ActAllow:
+			return libseccomp.ActAllow
+		}
+		return libseccomp.ActInvalid
+	}
+	mapArch := func(specArch specs.Arch) libseccomp.ScmpArch {
+		switch specArch {
+		case specs.ArchX86:
+			return libseccomp.ArchX86
+		case specs.ArchX86_64:
+			return libseccomp.ArchAMD64
+		case specs.ArchX32:
+			return libseccomp.ArchX32
+		case specs.ArchARM:
+			return libseccomp.ArchARM
+		case specs.ArchAARCH64:
+			return libseccomp.ArchARM64
+		case specs.ArchMIPS:
+			return libseccomp.ArchMIPS
+		case specs.ArchMIPS64:
+			return libseccomp.ArchMIPS64
+		case specs.ArchMIPS64N32:
+			return libseccomp.ArchMIPS64N32
+		case specs.ArchMIPSEL:
+			return libseccomp.ArchMIPSEL
+		case specs.ArchMIPSEL64:
+			return libseccomp.ArchMIPSEL64
+		case specs.ArchMIPSEL64N32:
+			return libseccomp.ArchMIPSEL64N32
+		case specs.ArchPPC:
+			return libseccomp.ArchPPC
+		case specs.ArchPPC64:
+			return libseccomp.ArchPPC64
+		case specs.ArchPPC64LE:
+			return libseccomp.ArchPPC64LE
+		case specs.ArchS390:
+			return libseccomp.ArchS390
+		case specs.ArchS390X:
+			return libseccomp.ArchS390X
+		case specs.ArchPARISC:
+			/* fallthrough */ /* for now */
+		case specs.ArchPARISC64:
+			/* fallthrough */ /* for now */
+		}
+		return libseccomp.ArchInvalid
+	}
+	mapOp := func(op specs.LinuxSeccompOperator) libseccomp.ScmpCompareOp {
+		switch op {
+		case specs.OpNotEqual:
+			return libseccomp.CompareNotEqual
+		case specs.OpLessThan:
+			return libseccomp.CompareLess
+		case specs.OpLessEqual:
+			return libseccomp.CompareLessOrEqual
+		case specs.OpEqualTo:
+			return libseccomp.CompareEqual
+		case specs.OpGreaterEqual:
+			return libseccomp.CompareGreaterEqual
+		case specs.OpGreaterThan:
+			return libseccomp.CompareGreater
+		case specs.OpMaskedEqual:
+			return libseccomp.CompareMaskedEqual
+		}
+		return libseccomp.CompareInvalid
+	}
+
+	filter, err := libseccomp.NewFilter(mapAction(spec.Linux.Seccomp.DefaultAction))
+	if err != nil {
+		return errors.Wrapf(err, "error creating seccomp filter with default action %q", spec.Linux.Seccomp.DefaultAction)
+	}
+	for _, arch := range spec.Linux.Seccomp.Architectures {
+		if err = filter.AddArch(mapArch(arch)); err != nil {
+			return errors.Wrapf(err, "error adding architecture %q(%q) to seccomp filter", arch, mapArch(arch))
+		}
+	}
+	for _, rule := range spec.Linux.Seccomp.Syscalls {
+		scnames := make(map[libseccomp.ScmpSyscall]string)
+		for _, name := range rule.Names {
+			scnum, err := libseccomp.GetSyscallFromName(name)
+			if err != nil {
+				logrus.Debugf("error mapping syscall %q to a syscall, ignoring %q rule for %q", name, rule.Action)
+				continue
+			}
+			scnames[scnum] = name
+		}
+		for scnum := range scnames {
+			if len(rule.Args) == 0 {
+				if err = filter.AddRule(scnum, mapAction(rule.Action)); err != nil {
+					return errors.Wrapf(err, "error adding a rule (%q:%q) to seccomp filter", scnames[scnum], rule.Action)
+				}
+				continue
+			}
+			var conditions []libseccomp.ScmpCondition
+			for _, arg := range rule.Args {
+				condition, err := libseccomp.MakeCondition(arg.Index, mapOp(arg.Op), arg.Value, arg.ValueTwo)
+				if err != nil {
+					return errors.Wrapf(err, "error building a seccomp condition %d:%v:%d:%d", arg.Index, arg.Op, arg.Value, arg.ValueTwo)
+				}
+				conditions = append(conditions, condition)
+			}
+			if err = filter.AddRuleConditional(scnum, mapAction(rule.Action), conditions); err != nil {
+				return errors.Wrapf(err, "error adding a conditional rule (%q:%q) to seccomp filter", scnames[scnum], rule.Action)
+			}
+		}
+	}
+	if err = filter.SetNoNewPrivsBit(spec.Process.NoNewPrivileges); err != nil {
+		return errors.Wrapf(err, "error setting no-new-privileges bit to %v", spec.Process.NoNewPrivileges)
+	}
+	err = filter.Load()
+	filter.Release()
+	if err != nil {
+		return errors.Wrapf(err, "error activating seccomp filter")
+	}
+	return nil
+}
diff --git a/vendor/github.com/projectatomic/buildah/chroot/seccomp_unsupported.go b/vendor/github.com/projectatomic/buildah/chroot/seccomp_unsupported.go
new file mode 100644
index 000000000..a5b74bf09
--- /dev/null
+++ b/vendor/github.com/projectatomic/buildah/chroot/seccomp_unsupported.go
@@ -0,0 +1,15 @@
+// +build !linux !seccomp
+
+package chroot
+
+import (
+	"github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+)
+
+func setSeccomp(spec *specs.Spec) error {
+	if spec.Linux.Seccomp != nil {
+		return errors.New("configured a seccomp filter without seccomp support?")
+	}
+	return nil
+}
diff --git a/vendor/github.com/projectatomic/buildah/chroot/selinux.go b/vendor/github.com/projectatomic/buildah/chroot/selinux.go
new file mode 100644
index 000000000..3e62d743d
--- /dev/null
+++ b/vendor/github.com/projectatomic/buildah/chroot/selinux.go
@@ -0,0 +1,22 @@
+// +build linux,selinux
+
+package chroot
+
+import (
+	"github.com/opencontainers/runtime-spec/specs-go"
+	selinux "github.com/opencontainers/selinux/go-selinux"
+	"github.com/opencontainers/selinux/go-selinux/label"
+	"github.com/pkg/errors"
+	"github.com/sirupsen/logrus"
+)
+
+// setSelinuxLabel sets the process label for child processes that we'll start.
+func setSelinuxLabel(spec *specs.Spec) error {
+	logrus.Debugf("setting selinux label")
+	if spec.Process.SelinuxLabel != "" && selinux.EnforceMode() != selinux.Disabled {
+		if err := label.SetProcessLabel(spec.Process.SelinuxLabel); err != nil {
+			return errors.Wrapf(err, "error setting process label to %q", spec.Process.SelinuxLabel)
+		}
+	}
+	return nil
+}
diff --git a/vendor/github.com/projectatomic/buildah/chroot/selinux_unsupported.go b/vendor/github.com/projectatomic/buildah/chroot/selinux_unsupported.go
new file mode 100644
index 000000000..1c6f48912
--- /dev/null
+++ b/vendor/github.com/projectatomic/buildah/chroot/selinux_unsupported.go
@@ -0,0 +1,18 @@
+// +build !linux !selinux
+
+package chroot
+
+import (
+	"github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+)
+
+func setSelinuxLabel(spec *specs.Spec) error {
+	if spec.Linux.MountLabel != "" {
+		return errors.New("configured an SELinux mount label without SELinux support?")
+	}
+	if spec.Process.SelinuxLabel != "" {
+		return errors.New("configured an SELinux process label without SELinux support?")
+	}
+	return nil
+}
diff --git a/vendor/github.com/projectatomic/buildah/chroot/unsupported.go b/vendor/github.com/projectatomic/buildah/chroot/unsupported.go
new file mode 100644
index 000000000..5312c0024
--- /dev/null
+++ b/vendor/github.com/projectatomic/buildah/chroot/unsupported.go
@@ -0,0 +1,15 @@
+// +build !linux
+
+package chroot
+
+import (
+	"io"
+
+	"github.com/opencontainers/runtime-spec/specs-go"
+	"github.com/pkg/errors"
+)
+
+// RunUsingChroot is not supported.
+func RunUsingChroot(spec *specs.Spec, bundlePath string, stdin io.Reader, stdout, stderr io.Writer) (err error) {
+	return errors.Errorf("--isolation chroot is not supported on this platform")
+}
diff --git a/vendor/github.com/projectatomic/buildah/chroot/util.go b/vendor/github.com/projectatomic/buildah/chroot/util.go
new file mode 100644
index 000000000..34cc77260
--- /dev/null
+++ b/vendor/github.com/projectatomic/buildah/chroot/util.go
@@ -0,0 +1,15 @@
+// +build linux
+
+package chroot
+
+func dedupeStringSlice(slice []string) []string {
+	done := make([]string, 0, len(slice))
+	m := make(map[string]struct{})
+	for _, s := range slice {
+		if _, present := m[s]; !present {
+			m[s] = struct{}{}
+			done = append(done, s)
+		}
+	}
+	return done
+}