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-rw-r--r--vendor/github.com/containers/buildah/chroot/run.go1308
1 files changed, 1308 insertions, 0 deletions
diff --git a/vendor/github.com/containers/buildah/chroot/run.go b/vendor/github.com/containers/buildah/chroot/run.go
new file mode 100644
index 000000000..58b7a883c
--- /dev/null
+++ b/vendor/github.com/containers/buildah/chroot/run.go
@@ -0,0 +1,1308 @@
+// +build linux
+
+package chroot
+
+import (
+ "bytes"
+ "encoding/json"
+ "fmt"
+ "io"
+ "os"
+ "os/exec"
+ "path/filepath"
+ "runtime"
+ "strconv"
+ "strings"
+ "sync"
+ "syscall"
+ "unsafe"
+
+ "github.com/containers/buildah/bind"
+ "github.com/containers/buildah/unshare"
+ "github.com/containers/buildah/util"
+ "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/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")
+ }
+ logrus.Debugf("config = %v", string(specbytes))
+
+ // 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, writeFd := 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
+ }
+ if err := unix.SetNonblock(writeFd, false); err != nil {
+ logrus.Errorf("error setting descriptor %d (%s) blocking: %v", relays[writeFd], fdDesc[writeFd], 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 this is the last of the data we'll be able to read
+ // from this descriptor, read as much as there is to read.
+ for rfd.Revents&unix.POLLHUP == unix.POLLHUP {
+ nr, err := unix.Read(int(rfd.Fd), b)
+ logIfNotRetryable(err, fmt.Sprintf("read %s: %v", fdDesc[int(rfd.Fd)], err))
+ if nr <= 0 {
+ break
+ }
+ if wfd, ok := relays[int(rfd.Fd)]; ok {
+ nwritten, err := buffers[wfd].Write(b[:nr])
+ if err != nil {
+ logrus.Debugf("buffer: %v", err)
+ break
+ }
+ if nwritten != nr {
+ logrus.Debugf("buffer: expected to buffer %d bytes, wrote %d", nr, nwritten)
+ break
+ }
+ }
+ }
+ }
+ 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
+ }
+ 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.
+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)
+ }
+ }
+
+ // Try to chroot into the root. Do this before we potentially block the syscall via the
+ // seccomp profile.
+ var oldst, newst unix.Stat_t
+ if err := unix.Stat(options.Spec.Root.Path, &oldst); err != nil {
+ fmt.Fprintf(os.Stderr, "error stat()ing intended root directory %q: %v\n", options.Spec.Root.Path, err)
+ os.Exit(1)
+ }
+ if err := unix.Chdir(options.Spec.Root.Path); err != nil {
+ fmt.Fprintf(os.Stderr, "error chdir()ing to intended root directory %q: %v\n", options.Spec.Root.Path, err)
+ os.Exit(1)
+ }
+ 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)
+ }
+ if err := unix.Stat("/", &newst); err != nil {
+ fmt.Fprintf(os.Stderr, "error stat()ing current root directory: %v\n", err)
+ os.Exit(1)
+ }
+ if oldst.Dev != newst.Dev || oldst.Ino != newst.Ino {
+ fmt.Fprintf(os.Stderr, "unknown error chroot()ing into directory %q: %v\n", options.Spec.Root.Path, err)
+ os.Exit(1)
+ }
+ logrus.Debugf("chrooted into %q", options.Spec.Root.Path)
+
+ // 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 change to the directory.
+ cwd := options.Spec.Process.Cwd
+ if !filepath.IsAbs(cwd) {
+ cwd = "/" + cwd
+ }
+ cwd = filepath.Clean(cwd)
+ if err := unix.Chdir("/"); err != nil {
+ fmt.Fprintf(os.Stderr, "error chdir()ing into new root directory %q: %v\n", options.Spec.Root.Path, err)
+ os.Exit(1)
+ }
+ if err := unix.Chdir(cwd); err != nil {
+ fmt.Fprintf(os.Stderr, "error chdir()ing into directory %q under root %q: %v\n", cwd, options.Spec.Root.Path, err)
+ os.Exit(1)
+ }
+ logrus.Debugf("changed working directory to %q", 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-only.
+ 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.MkdirAll(target, 0111); err != nil {
+ return undoBinds, errors.Wrapf(err, "error creating mountpoint %q in mount namespace", target)
+ }
+ removes = append(removes, target)
+ } else {
+ if err = os.MkdirAll(filepath.Dir(target), 0111); err != nil {
+ return undoBinds, errors.Wrapf(err, "error ensuring parent of mountpoint %q (%q) is present in mount namespace", target, filepath.Dir(target))
+ }
+ 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)
+ }
+ }
+
+ // Create an empty directory for to use for masking directories.
+ roEmptyDir := filepath.Join(bundlePath, "empty")
+ if len(spec.Linux.MaskedPaths) > 0 {
+ if err := os.Mkdir(roEmptyDir, 0700); err != nil {
+ return undoBinds, errors.Wrapf(err, "error creating empty directory %q", roEmptyDir)
+ }
+ removes = append(removes, roEmptyDir)
+ }
+
+ // 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 read-only bind mount an empty directory on it.
+ roFlags := uintptr(syscall.MS_BIND | syscall.MS_NOSUID | syscall.MS_NODEV | syscall.MS_NOEXEC | syscall.MS_RDONLY)
+ if !isReadOnly || (hasContent && isAccessible) {
+ if err = unix.Mount(roEmptyDir, target, "bind", roFlags, ""); 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
+}
generated by cgit v1.2.3-54-g00ecf (git 2.39.0) at 2024-12-27 21:25:38 +0000