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Revert "Add chroot for tar packing operations"

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This reverts commit 3e057d527d.

Signed-off-by: Tibor Vass <tibor@docker.com>
This commit is contained in:
Tibor Vass 2019-06-12 04:06:14 +00:00
parent a33a82b42f
commit 96df6d4d0b
7 changed files with 7 additions and 211 deletions
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8
daemon/archive.go
View file

@ -39,11 +39,11 @@ func extractArchive(i interface{}, src io.Reader, dst string, opts *archive.TarO
return chrootarchive.UntarWithRoot(src, dst, opts, root)
}
func archivePath(i interface{}, src string, opts *archive.TarOptions, root string) (io.ReadCloser, error) {
func archivePath(i interface{}, src string, opts *archive.TarOptions) (io.ReadCloser, error) {
if ap, ok := i.(archiver); ok {
return ap.ArchivePath(src, opts)
}
return chrootarchive.Tar(src, opts, root)
return archive.TarWithOptions(src, opts)
}
// ContainerCopy performs a deprecated operation of archiving the resource at
@ -239,7 +239,7 @@ func (daemon *Daemon) containerArchivePath(container *container.Container, path
sourceDir, sourceBase := driver.Dir(resolvedPath), driver.Base(resolvedPath)
opts := archive.TarResourceRebaseOpts(sourceBase, driver.Base(absPath))
data, err := archivePath(driver, sourceDir, opts, container.BaseFS.Path())
data, err := archivePath(driver, sourceDir, opts)
if err != nil {
return nil, nil, err
}
@ -433,7 +433,7 @@ func (daemon *Daemon) containerCopy(container *container.Container, resource str
archive, err := archivePath(driver, basePath, &archive.TarOptions{
Compression: archive.Uncompressed,
IncludeFiles: filter,
}, container.BaseFS.Path())
})
if err != nil {
return nil, err
}

2
daemon/export.go
View file

@ -70,7 +70,7 @@ func (daemon *Daemon) containerExport(container *container.Container) (arch io.R
Compression: archive.Uncompressed,
UIDMaps: daemon.idMapping.UIDs(),
GIDMaps: daemon.idMapping.GIDs(),
}, basefs.Path())
})
if err != nil {
rwlayer.Unmount()
return nil, err

8
pkg/chrootarchive/archive.go
View file

@ -87,11 +87,3 @@ func untarHandler(tarArchive io.Reader, dest string, options *archive.TarOptions
return invokeUnpack(r, dest, options, root)
}
// Tar tars the requested path while chrooted to the specified root.
func Tar(srcPath string, options *archive.TarOptions, root string) (io.ReadCloser, error) {
if options == nil {
options = &archive.TarOptions{}
}
return invokePack(srcPath, options, root)
}

98
pkg/chrootarchive/archive_unix.go
View file

@ -12,11 +12,9 @@ import (
"os"
"path/filepath"
"runtime"
"strings"
"github.com/docker/docker/pkg/archive"
"github.com/docker/docker/pkg/reexec"
"github.com/pkg/errors"
)
// untar is the entry-point for docker-untar on re-exec. This is not used on
@ -26,7 +24,7 @@ func untar() {
runtime.LockOSThread()
flag.Parse()
var options archive.TarOptions
var options *archive.TarOptions
//read the options from the pipe "ExtraFiles"
if err := json.NewDecoder(os.NewFile(3, "options")).Decode(&options); err != nil {
@ -47,7 +45,7 @@ func untar() {
fatal(err)
}
if err := archive.Unpack(os.Stdin, dst, &options); err != nil {
if err := archive.Unpack(os.Stdin, dst, options); err != nil {
fatal(err)
}
// fully consume stdin in case it is zero padded
@ -59,9 +57,6 @@ func untar() {
}
func invokeUnpack(decompressedArchive io.Reader, dest string, options *archive.TarOptions, root string) error {
if root == "" {
return errors.New("must specify a root to chroot to")
}
// We can't pass a potentially large exclude list directly via cmd line
// because we easily overrun the kernel's max argument/environment size
@ -117,92 +112,3 @@ func invokeUnpack(decompressedArchive io.Reader, dest string, options *archive.T
}
return nil
}
func tar() {
runtime.LockOSThread()
flag.Parse()
src := flag.Arg(0)
var root string
if len(flag.Args()) > 1 {
root = flag.Arg(1)
}
if root == "" {
root = src
}
if err := realChroot(root); err != nil {
fatal(err)
}
var options archive.TarOptions
if err := json.NewDecoder(os.Stdin).Decode(&options); err != nil {
fatal(err)
}
rdr, err := archive.TarWithOptions(src, &options)
if err != nil {
fatal(err)
}
defer rdr.Close()
if _, err := io.Copy(os.Stdout, rdr); err != nil {
fatal(err)
}
os.Exit(0)
}
func invokePack(srcPath string, options *archive.TarOptions, root string) (io.ReadCloser, error) {
if root == "" {
return nil, errors.New("root path must not be empty")
}
relSrc, err := filepath.Rel(root, srcPath)
if err != nil {
return nil, err
}
if relSrc == "." {
relSrc = "/"
}
if relSrc[0] != '/' {
relSrc = "/" + relSrc
}
// make sure we didn't trim a trailing slash with the call to `Rel`
if strings.HasSuffix(srcPath, "/") && !strings.HasSuffix(relSrc, "/") {
relSrc += "/"
}
cmd := reexec.Command("docker-tar", relSrc, root)
errBuff := bytes.NewBuffer(nil)
cmd.Stderr = errBuff
tarR, tarW := io.Pipe()
cmd.Stdout = tarW
stdin, err := cmd.StdinPipe()
if err != nil {
return nil, errors.Wrap(err, "error getting options pipe for tar process")
}
if err := cmd.Start(); err != nil {
return nil, errors.Wrap(err, "tar error on re-exec cmd")
}
go func() {
err := cmd.Wait()
err = errors.Wrapf(err, "error processing tar file: %s", errBuff)
tarW.CloseWithError(err)
}()
if err := json.NewEncoder(stdin).Encode(options); err != nil {
stdin.Close()
return nil, errors.Wrap(err, "tar json encode to pipe failed")
}
stdin.Close()
return tarR, nil
}

94
pkg/chrootarchive/archive_unix_test.go
View file

@ -3,14 +3,11 @@
package chrootarchive
import (
gotar "archive/tar"
"bytes"
"io"
"io/ioutil"
"os"
"path"
"path/filepath"
"strings"
"testing"
"github.com/docker/docker/pkg/archive"
@ -78,94 +75,3 @@ func TestUntarWithMaliciousSymlinks(t *testing.T) {
assert.NilError(t, err)
assert.Equal(t, string(hostData), "pwn3d")
}
// Test for CVE-2018-15664
// Assures that in the case where an "attacker" controlled path is a symlink to
// some path outside of a container's rootfs that we do not unwittingly leak
// host data into the archive.
func TestTarWithMaliciousSymlinks(t *testing.T) {
dir, err := ioutil.TempDir("", t.Name())
assert.NilError(t, err)
// defer os.RemoveAll(dir)
t.Log(dir)
root := filepath.Join(dir, "root")
err = os.MkdirAll(root, 0755)
assert.NilError(t, err)
hostFileData := []byte("I am a host file")
// Add a file into a directory above root
// Ensure that we can't access this file while tarring.
err = ioutil.WriteFile(filepath.Join(dir, "host-file"), hostFileData, 0644)
assert.NilError(t, err)
safe := filepath.Join(root, "safe")
err = unix.Symlink(dir, safe)
assert.NilError(t, err)
data := filepath.Join(dir, "data")
err = os.MkdirAll(data, 0755)
assert.NilError(t, err)
type testCase struct {
p string
includes []string
}
cases := []testCase{
{p: safe, includes: []string{"host-file"}},
{p: safe + "/", includes: []string{"host-file"}},
{p: safe, includes: nil},
{p: safe + "/", includes: nil},
{p: root, includes: []string{"safe/host-file"}},
{p: root, includes: []string{"/safe/host-file"}},
{p: root, includes: nil},
}
maxBytes := len(hostFileData)
for _, tc := range cases {
t.Run(path.Join(tc.p+"_"+strings.Join(tc.includes, "_")), func(t *testing.T) {
// Here if we use archive.TarWithOptions directly or change the "root" parameter
// to be the same as "safe", data from the host will be leaked into the archive
var opts *archive.TarOptions
if tc.includes != nil {
opts = &archive.TarOptions{
IncludeFiles: tc.includes,
}
}
rdr, err := Tar(tc.p, opts, root)
assert.NilError(t, err)
defer rdr.Close()
tr := gotar.NewReader(rdr)
assert.Assert(t, !isDataInTar(t, tr, hostFileData, int64(maxBytes)), "host data leaked to archive")
})
}
}
func isDataInTar(t *testing.T, tr *gotar.Reader, compare []byte, maxBytes int64) bool {
for {
h, err := tr.Next()
if err == io.EOF {
break
}
assert.NilError(t, err)
if h.Size == 0 {
continue
}
assert.Assert(t, h.Size <= maxBytes, "%s: file size exceeds max expected size %d: %d", h.Name, maxBytes, h.Size)
data := make([]byte, int(h.Size))
_, err = io.ReadFull(tr, data)
assert.NilError(t, err)
if bytes.Contains(data, compare) {
return true
}
}
return false
}

7
pkg/chrootarchive/archive_windows.go
View file

@ -20,10 +20,3 @@ func invokeUnpack(decompressedArchive io.ReadCloser,
// do the unpack. We call inline instead within the daemon process.
return archive.Unpack(decompressedArchive, longpath.AddPrefix(dest), options)
}
func invokePack(srcPath string, options *archive.TarOptions, root string) (io.ReadCloser, error) {
// Windows is different to Linux here because Windows does not support
// chroot. Hence there is no point sandboxing a chrooted process to
// do the pack. We call inline instead within the daemon process.
return archive.TarWithOptions(srcPath, options)
}

1
pkg/chrootarchive/init_unix.go
View file

@ -14,7 +14,6 @@ import (
func init() {
reexec.Register("docker-applyLayer", applyLayer)
reexec.Register("docker-untar", untar)
reexec.Register("docker-tar", tar)
}
func fatal(err error) {