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Merge pull request #82143 from soltysh/cp_no_links

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Remove symlink support from kubectl cp
This commit is contained in:
Kubernetes Prow Robot 2019-09-03 16:01:24 -07:00 committed by GitHub
commit 35e0f17a33
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3 changed files with 46 additions and 68 deletions
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1
hack/.staticcheck_failures
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@ -26,7 +26,6 @@ pkg/credentialprovider
pkg/credentialprovider/aws
pkg/credentialprovider/azure
pkg/kubeapiserver/admission
pkg/kubectl/cmd/cp
pkg/kubectl/cmd/get
pkg/kubelet/apis/podresources
pkg/kubelet/cm/devicemanager

76
pkg/kubectl/cmd/cp/cp.go
View File

@ -45,6 +45,15 @@ var (
# !!!Important Note!!!
# Requires that the 'tar' binary is present in your container
# image. If 'tar' is not present, 'kubectl cp' will fail.
#
# For advanced use cases, such as symlinks, wildcard expansion or
# file mode preservation consider using 'kubectl exec'.
# Copy /tmp/foo local file to /tmp/bar in a remote pod in namespace <some-namespace>
tar cf - /tmp/foo | kubectl exec -i -n <some-namespace> <some-pod> -- tar xf - -C /tmp/bar
# Copy /tmp/foo from a remote pod to /tmp/bar locally
kubectl exec -n <some-namespace> <some-pod> -- tar cf - /tmp/foo | tar xf - -C /tmp/bar
# Copy /tmp/foo_dir local directory to /tmp/bar_dir in a remote pod in the default namespace
kubectl cp /tmp/foo_dir <some-pod>:/tmp/bar_dir
@ -71,8 +80,9 @@ type CopyOptions struct {
Namespace string
NoPreserve bool
ClientConfig *restclient.Config
Clientset kubernetes.Interface
ClientConfig *restclient.Config
Clientset kubernetes.Interface
ExecParentCmdName string
genericclioptions.IOStreams
}
@ -143,6 +153,10 @@ func extractFileSpec(arg string) (fileSpec, error) {
// Complete completes all the required options
func (o *CopyOptions) Complete(f cmdutil.Factory, cmd *cobra.Command) error {
if cmd.Parent() != nil {
o.ExecParentCmdName = cmd.Parent().CommandPath()
}
var err error
o.Namespace, _, err = f.ToRawKubeConfigLoader().Namespace()
if err != nil {
@ -307,7 +321,7 @@ func (o *CopyOptions) copyFromPod(src, dest fileSpec) error {
// remove extraneous path shortcuts - these could occur if a path contained extra "../"
// and attempted to navigate beyond "/" in a remote filesystem
prefix = stripPathShortcuts(prefix)
return o.untarAll(reader, dest.File, prefix)
return o.untarAll(src, reader, dest.File, prefix)
}
// stripPathShortcuts removes any leading or trailing "../" from a given path
@ -412,7 +426,8 @@ func recursiveTar(srcBase, srcFile, destBase, destFile string, tw *tar.Writer) e
return nil
}
func (o *CopyOptions) untarAll(reader io.Reader, destDir, prefix string) error {
func (o *CopyOptions) untarAll(src fileSpec, reader io.Reader, destDir, prefix string) error {
symlinkWarningPrinted := false
// TODO: use compression here?
tarReader := tar.NewReader(reader)
for {
@ -453,48 +468,25 @@ func (o *CopyOptions) untarAll(reader io.Reader, destDir, prefix string) error {
continue
}
// We need to ensure that the destination file is always within boundries
// of the destination directory. This prevents any kind of path traversal
// from within tar archive.
evaledPath, err := filepath.EvalSymlinks(baseName)
if mode&os.ModeSymlink != 0 {
if !symlinkWarningPrinted && len(o.ExecParentCmdName) > 0 {
fmt.Fprintf(o.IOStreams.ErrOut, "warning: file %q is a symlink, skipping (consider using \"%s exec -n %q %q -- tar cf - %q | tar xf -\")\n", destFileName, o.ExecParentCmdName, src.PodNamespace, src.PodName, src.File)
symlinkWarningPrinted = true
continue
}
fmt.Fprintf(o.IOStreams.ErrOut, "warning: skipping symlink: %q -> %q\n", destFileName, header.Linkname)
continue
}
outFile, err := os.Create(destFileName)
if err != nil {
return err
}
// For scrutiny we verify both the actual destination as well as we follow
// all the links that might lead outside of the destination directory.
if !isDestRelative(destDir, filepath.Join(evaledPath, filepath.Base(destFileName))) {
fmt.Fprintf(o.IOStreams.ErrOut, "warning: file %q is outside target destination, skipping\n", destFileName)
continue
defer outFile.Close()
if _, err := io.Copy(outFile, tarReader); err != nil {
return err
}
if mode&os.ModeSymlink != 0 {
linkname := header.Linkname
// We need to ensure that the link destination is always within boundries
// of the destination directory. This prevents any kind of path traversal
// from within tar archive.
linkTarget := linkname
if !filepath.IsAbs(linkname) {
linkTarget = filepath.Join(evaledPath, linkname)
}
if !isDestRelative(destDir, linkTarget) {
fmt.Fprintf(o.IOStreams.ErrOut, "warning: link %q is pointing to %q which is outside target destination, skipping\n", destFileName, header.Linkname)
continue
}
if err := os.Symlink(linkname, destFileName); err != nil {
return err
}
} else {
outFile, err := os.Create(destFileName)
if err != nil {
return err
}
defer outFile.Close()
if _, err := io.Copy(outFile, tarReader); err != nil {
return err
}
if err := outFile.Close(); err != nil {
return err
}
if err := outFile.Close(); err != nil {
return err
}
}

37
pkg/kubectl/cmd/cp/cp_test.go
View File

@ -302,11 +302,13 @@ func TestTarUntar(t *testing.T) {
{
name: "gakki",
data: "tmp/gakki",
omitted: true,
fileType: SymLink,
},
{
name: "relative_to_dest",
data: path.Join(dir2, "foo"),
omitted: true,
fileType: SymLink,
},
{
@ -358,7 +360,7 @@ func TestTarUntar(t *testing.T) {
}
reader := bytes.NewBuffer(writer.Bytes())
if err := opts.untarAll(reader, dir2, ""); err != nil {
if err := opts.untarAll(fileSpec{}, reader, dir2, ""); err != nil {
t.Fatalf("unexpected error: %v", err)
}
@ -419,7 +421,7 @@ func TestTarUntarWrongPrefix(t *testing.T) {
}
reader := bytes.NewBuffer(writer.Bytes())
err = opts.untarAll(reader, dir2, "verylongprefix-showing-the-tar-was-tempered-with")
err = opts.untarAll(fileSpec{}, reader, dir2, "verylongprefix-showing-the-tar-was-tempered-with")
if err == nil || !strings.Contains(err.Error(), "tar contents corrupted") {
t.Fatalf("unexpected error: %v", err)
}
@ -534,7 +536,7 @@ func TestBadTar(t *testing.T) {
}
opts := NewCopyOptions(genericclioptions.NewTestIOStreamsDiscard())
if err := opts.untarAll(&buf, dir, "/prefix"); err != nil {
if err := opts.untarAll(fileSpec{}, &buf, dir, "/prefix"); err != nil {
t.Errorf("unexpected error: %v ", err)
t.FailNow()
}
@ -780,35 +782,20 @@ func TestUntar(t *testing.T) {
expected: "",
}}
mkExpectation := func(expected, suffix string) string {
if expected == "" {
return ""
}
return expected + suffix
}
mkBacklinkExpectation := func(expected, suffix string) string {
// "resolve" the back link relative to the expectation
targetDir := filepath.Dir(filepath.Dir(expected))
// If the "resolved" target is not nested in basedir, it is escaping.
if !filepath.HasPrefix(targetDir, basedir) {
return ""
}
return expected + suffix
}
links := []file{}
for _, f := range files {
links = append(links, file{
path: f.path + "-innerlink",
linkTarget: "link-target",
expected: mkExpectation(f.expected, "-innerlink"),
expected: "",
}, file{
path: f.path + "-innerlink-abs",
linkTarget: filepath.Join(basedir, "link-target"),
expected: mkExpectation(f.expected, "-innerlink-abs"),
expected: "",
}, file{
path: f.path + "-backlink",
linkTarget: filepath.Join("..", "link-target"),
expected: mkBacklinkExpectation(f.expected, "-backlink"),
expected: "",
}, file{
path: f.path + "-outerlink-abs",
linkTarget: filepath.Join(testdir, "link-target"),
@ -832,7 +819,7 @@ func TestUntar(t *testing.T) {
file{
path: "nested/again/back-link",
linkTarget: "../../nested",
expected: filepath.Join(basedir, "nested/again/back-link"),
expected: "",
},
file{
path: "nested/again/back-link/../../../back-link-file",
@ -844,7 +831,7 @@ func TestUntar(t *testing.T) {
file{
path: "nested/back-link-first",
linkTarget: "../",
expected: filepath.Join(basedir, "nested/back-link-first"),
expected: "",
},
file{
path: "nested/back-link-first/back-link-second",
@ -892,7 +879,7 @@ func TestUntar(t *testing.T) {
output := (*testWriter)(t)
opts := NewCopyOptions(genericclioptions.IOStreams{In: &bytes.Buffer{}, Out: output, ErrOut: output})
require.NoError(t, opts.untarAll(buf, filepath.Join(basedir), ""))
require.NoError(t, opts.untarAll(fileSpec{}, buf, filepath.Join(basedir), ""))
filepath.Walk(testdir, func(path string, info os.FileInfo, err error) error {
if err != nil {
@ -943,7 +930,7 @@ func TestUntar_SingleFile(t *testing.T) {
output := (*testWriter)(t)
opts := NewCopyOptions(genericclioptions.IOStreams{In: &bytes.Buffer{}, Out: output, ErrOut: output})
require.NoError(t, opts.untarAll(buf, filepath.Join(dest), srcName))
require.NoError(t, opts.untarAll(fileSpec{}, buf, filepath.Join(dest), srcName))
cmpFileData(t, dest, content)
}