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host_orchestrator: reject archive entries that escape the extraction dir #3015

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280c514
host_orchestrator: reject archive entries that escape the extraction dir
anagnorisis2peripeteia Aug 13, 2026
15447bf
tools/*/cw/Containerfile is now based on trixie
0405ysj Aug 6, 2026
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23 changes: 22 additions & 1 deletion frontend/src/host_orchestrator/orchestrator/userartifacts.go
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Original file line number Diff line number Diff line change
Expand Up @@ -312,6 +312,13 @@ func extractFile(dst string, src string) error {
return nil
}

// isSafeToExtract reports whether target (already joined onto dst) stays within
// dst, rejecting paths that escape via ".." components or an absolute path
func isSafeToExtract(dst string, target string) bool {
rel, err := filepath.Rel(dst, target)
return err == nil && rel != ".." && !strings.HasPrefix(rel, ".."+string(os.PathSeparator))
}

func untar(dst string, src string) error {
r, err := os.Open(src)
if err != nil {
Expand All @@ -336,6 +343,9 @@ func untar(dst string, src string) error {
continue
}
target := filepath.Join(dst, header.Name)
if !isSafeToExtract(dst, target) {
return fmt.Errorf("archive entry %q escapes the extraction directory", header.Name)
}
switch header.Typeflag {
case tar.TypeDir:
if _, err := os.Stat(target); err != nil {
Expand All @@ -356,6 +366,13 @@ func untar(dst string, src string) error {
}
f.Close()
case tar.TypeSymlink:
linkTarget := header.Linkname
if !filepath.IsAbs(linkTarget) {
linkTarget = filepath.Join(filepath.Dir(target), linkTarget)
}
if !isSafeToExtract(dst, linkTarget) {
return fmt.Errorf("symlink entry %q targets outside the extraction directory", header.Name)
}
if err := os.Symlink(header.Linkname, target); err != nil {
return err
}
Expand Down Expand Up @@ -391,7 +408,11 @@ func unzip(dstDir string, src string) error {
if f.Mode().IsDir() {
continue
}
if err := extractTo(filepath.Join(dstDir, f.Name), f); err != nil {
target := filepath.Join(dstDir, f.Name)
if !isSafeToExtract(dstDir, target) {
return fmt.Errorf("archive entry %q escapes the extraction directory", f.Name)
}
if err := extractTo(target, f); err != nil {
return err
}
}
Expand Down
218 changes: 119 additions & 99 deletions frontend/src/host_orchestrator/orchestrator/userartifacts_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -238,170 +238,135 @@ func TestStatArtifactSucceeds(t *testing.T) {
}

func TestExtractArtifactSucceedsWithZipFormat(t *testing.T) {
rootDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, rootDir)
opts := UserArtifactsManagerOpts{RootDir: rootDir}
uam, err := NewUserArtifactsManagerImpl(opts)
if err != nil {
t.Fatal(err)
}
tempDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, tempDir)
zipContents := map[string]string{
"alpha.txt": "This is alpha.\n",
"bravo.txt": "This is bravo.\n",
"charlie.txt": "This is charlie.\n",
"delta.txt": "This is delta.\n",
}
tempDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, tempDir)
zipFile, err := createZip(tempDir, zipContents)
if err != nil {
t.Fatal(err)
}
data, err := ioutil.ReadFile(zipFile)
if err != nil {
t.Fatal(err)
}
checksum := getSha256Sum(data)
chunk := UserArtifactChunk{
Name: filepath.Base(zipFile),
OffsetBytes: 0,
SizeBytes: int64(len(data)),
FileSizeBytes: int64(len(data)),
File: bytes.NewReader(data),
}
if err := uam.UpdateArtifact(checksum, chunk); err != nil {
t.Fatal(err)
}

if err := uam.ExtractArtifact(checksum); err != nil {
extractedDir, err := updateAndExtractArtifact(t, zipFile)
if err != nil {
t.Fatal(err)
}
if got, err := getContents(filepath.Join(rootDir, fmt.Sprintf("%s_extracted", checksum))); err != nil {
if got, err := getContents(extractedDir); err != nil {
t.Fatal(err)
} else if diff := cmp.Diff(zipContents, got); diff != "" {
t.Fatalf("content mismatch (-want +got):\n%s", diff)
}
}

func TestExtractArtifactSucceedsWithTarGzFormat(t *testing.T) {
rootDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, rootDir)
opts := UserArtifactsManagerOpts{RootDir: rootDir}
uam, err := NewUserArtifactsManagerImpl(opts)
if err != nil {
t.Fatal(err)
}
tarContents := map[string]string{
"foo/alpha.txt": "This is alpha.\n",
"foo/bravo.txt": "This is bravo.\n",
"bar/charlie.txt": "This is charlie.\n",
"delta.txt": "This is delta.\n",
}
tempDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, tempDir)
tarContents := map[string]archiveEntry{
"foo/alpha.txt": {Content: "This is alpha.\n"},
"foo/bravo.txt": {Content: "This is bravo.\n"},
"bar/charlie.txt": {Content: "This is charlie.\n"},
"delta.txt": {Content: "This is delta.\n"},
}
tarFile, err := createTarGz(tempDir, tarContents)
if err != nil {
t.Fatal(err)
}
data, err := ioutil.ReadFile(tarFile)

extractedDir, err := updateAndExtractArtifact(t, tarFile)
if err != nil {
t.Fatal(err)
}
checksum := getSha256Sum(data)
chunk := UserArtifactChunk{
Name: filepath.Base(tarFile),
OffsetBytes: 0,
SizeBytes: int64(len(data)),
FileSizeBytes: int64(len(data)),
File: bytes.NewReader(data),
tarWant := map[string]string{}
for name, entry := range tarContents {
tarWant[name] = entry.Content
}
if err := uam.UpdateArtifact(checksum, chunk); err != nil {
if got, err := getContents(extractedDir); err != nil {
t.Fatal(err)
} else if diff := cmp.Diff(tarWant, got); diff != "" {
t.Fatalf("content mismatch (-want +got):\n%s", diff)
}
}

if err := uam.ExtractArtifact(checksum); err != nil {
func TestExtractArtifactFailsWithInvalidFileFormat(t *testing.T) {
tempDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, tempDir)
archive := filepath.Join(tempDir, testFileName)
if err := ioutil.WriteFile(archive, []byte(testFileData), 0644); err != nil {
t.Fatal(err)
}
if got, err := getContents(filepath.Join(rootDir, fmt.Sprintf("%s_extracted", checksum))); err != nil {
t.Fatal(err)
} else if diff := cmp.Diff(tarContents, got); diff != "" {
t.Fatalf("content mismatch (-want +got):\n%s", diff)
if _, err := updateAndExtractArtifact(t, archive); err == nil {
t.Fatal("Expected an error")
}
}

func TestExtractArtifactFailsWithInvalidFileFormat(t *testing.T) {
rootDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, rootDir)
opts := UserArtifactsManagerOpts{RootDir: rootDir}
uam, err := NewUserArtifactsManagerImpl(opts)
func TestExtractArtifactAfterArtifactIsFullyExtractedFails(t *testing.T) {
tempDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, tempDir)
archive, err := createTarGz(tempDir, map[string]archiveEntry{"file": {Content: "content\n"}})
if err != nil {
t.Fatal(err)
}
checksum := getSha256Sum([]byte(testFileData))
chunk := UserArtifactChunk{
Name: testFileName,
OffsetBytes: 0,
SizeBytes: int64(len(testFileData)),
FileSizeBytes: int64(len(testFileData)),
File: strings.NewReader(testFileData),
}
if err := uam.UpdateArtifact(checksum, chunk); err != nil {
// Extract twice on the same manager: the first extraction must succeed and
// the second must fail because the artifact is already extracted.
uam, checksum := updateArtifact(t, archive)
if err := uam.ExtractArtifact(checksum); err != nil {
t.Fatal(err)
}

if err := uam.ExtractArtifact(checksum); err == nil {
t.Fatal("Expected an error")
}
}

func TestExtractArtifactAfterArtifactIsFullyExtractedFails(t *testing.T) {
func TestExtractArtifactFailsArtifactNotFound(t *testing.T) {
rootDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, rootDir)
opts := UserArtifactsManagerOpts{RootDir: rootDir}
uam, err := NewUserArtifactsManagerImpl(opts)
if err != nil {
t.Fatal(err)
}

if err := uam.ExtractArtifact("foo"); err == nil {
t.Fatal("Expected an error")
}
}

func TestExtractArtifactFailsWithTarPathTraversal(t *testing.T) {
tempDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, tempDir)
archive, err := createTarGz(tempDir, map[string]string{"file": "content\n"})
archive, err := createTarGz(tempDir, map[string]archiveEntry{"../../../../../../PWNED": {Content: "owned"}})
if err != nil {
t.Fatal(err)
}
data, err := ioutil.ReadFile(archive)
if err != nil {
t.Fatal(err)
}
checksum := getSha256Sum(data)
chunk := UserArtifactChunk{
Name: filepath.Base(archive),
OffsetBytes: 0,
SizeBytes: int64(len(data)),
FileSizeBytes: int64(len(data)),
File: bytes.NewReader(data),
}
if err := uam.UpdateArtifact(checksum, chunk); err != nil {
t.Fatal(err)
if _, err := updateAndExtractArtifact(t, archive); err == nil {
t.Fatal("Expected an error")
}
if err := uam.ExtractArtifact(checksum); err != nil {
}

func TestExtractArtifactFailsWithZipPathTraversal(t *testing.T) {
tempDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, tempDir)
archive, err := createZip(tempDir, map[string]string{"../../../../../../PWNED": "owned"})
if err != nil {
t.Fatal(err)
}

if err := uam.ExtractArtifact(checksum); err == nil {
if _, err := updateAndExtractArtifact(t, archive); err == nil {
t.Fatal("Expected an error")
}
}

func TestExtractArtifactFailsArtifactNotFound(t *testing.T) {
rootDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, rootDir)
opts := UserArtifactsManagerOpts{RootDir: rootDir}
uam, err := NewUserArtifactsManagerImpl(opts)
func TestExtractArtifactFailsWithTarSymlinkEscape(t *testing.T) {
tempDir := orchtesting.TempDir(t)
defer orchtesting.RemoveDir(t, tempDir)
archive, err := createTarGz(tempDir, map[string]archiveEntry{"sneak": {Symlink: "../../../../../../etc"}})
if err != nil {
t.Fatal(err)
}

if err := uam.ExtractArtifact("foo"); err == nil {
if _, err := updateAndExtractArtifact(t, archive); err == nil {
t.Fatal("Expected an error")
}
}
Expand Down Expand Up @@ -650,7 +615,15 @@ func getSubdirs(path string) []string {
return subdirs
}

func createTarGz(dir string, contents map[string]string) (string, error) {
// archiveEntry describes an entry to add to an archive built by createTarGz: a
// regular file holding Content, or, when Symlink is non-empty, a symbolic link
// pointing at Symlink (used to exercise the symlink-escape guard).
type archiveEntry struct {
Content string
Symlink string
}

func createTarGz(dir string, contents map[string]archiveEntry) (string, error) {
tarFile, err := ioutil.TempFile(dir, "*.tar.gz")
if err != nil {
return "", err
Expand All @@ -665,7 +638,19 @@ func createTarGz(dir string, contents map[string]string) (string, error) {

directories := map[string]struct{}{}

for name, content := range contents {
for name, entry := range contents {
if entry.Symlink != "" {
header := tar.Header{
Name: name,
Typeflag: tar.TypeSymlink,
Linkname: entry.Symlink,
Mode: 0777,
}
if err := tarWriter.WriteHeader(&header); err != nil {
return "", err
}
continue
}
dir, _ := filepath.Split(name)
dirPaths := getSubdirs(dir)
for _, dp := range dirPaths {
Expand All @@ -684,15 +669,15 @@ func createTarGz(dir string, contents map[string]string) (string, error) {
}
header := tar.Header{
Name: name,
Size: int64(len(content)),
Size: int64(len(entry.Content)),
Mode: 0555,
}
if err := tarWriter.WriteHeader(&header); err != nil {
return "", err
}
if n, err := tarWriter.Write([]byte(content)); err != nil {
if n, err := tarWriter.Write([]byte(entry.Content)); err != nil {
return "", err
} else if n != len(content) {
} else if n != len(entry.Content) {
return "", fmt.Errorf("Failed to write entire file: %s", name)
}
}
Expand All @@ -707,3 +692,38 @@ func getChunkStateItemList(cs *chunkState) []chunkStateItem {
})
return items
}

// updateArtifact uploads the archive at archivePath as a single chunk, returning
// the manager and the artifact checksum so callers can extract it.
func updateArtifact(t *testing.T, archivePath string) (*UserArtifactsManagerImpl, string) {
rootDir := orchtesting.TempDir(t)
t.Cleanup(func() { orchtesting.RemoveDir(t, rootDir) })
uam, err := NewUserArtifactsManagerImpl(UserArtifactsManagerOpts{RootDir: rootDir})
if err != nil {
t.Fatal(err)
}
data, err := ioutil.ReadFile(archivePath)
if err != nil {
t.Fatal(err)
}
checksum := getSha256Sum(data)
chunk := UserArtifactChunk{
Name: filepath.Base(archivePath),
OffsetBytes: 0,
SizeBytes: int64(len(data)),
FileSizeBytes: int64(len(data)),
File: bytes.NewReader(data),
}
if err := uam.UpdateArtifact(checksum, chunk); err != nil {
t.Fatal(err)
}
return uam, checksum
}

// updateAndExtractArtifact uploads the archive at archivePath as a single chunk and
// extracts it, returning the directory the artifact was extracted into so
// callers can inspect the result.
func updateAndExtractArtifact(t *testing.T, archivePath string) (string, error) {
uam, checksum := updateArtifact(t, archivePath)
return uam.ExtractedArtifactPath(checksum), uam.ExtractArtifact(checksum)
}
8 changes: 1 addition & 7 deletions tools/buildutils/cw/Containerfile
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Original file line number Diff line number Diff line change
@@ -1,16 +1,10 @@
FROM mirror.gcr.io/library/debian:bookworm-20250811 AS base
FROM mirror.gcr.io/library/debian:13 AS base

ENV DEBIAN_FRONTEND=noninteractive

RUN apt update -y && apt upgrade -y
RUN apt install -y sudo devscripts

# Download newer version of golang with keep using bookworm for building debian
# packages.
RUN echo "deb http://deb.debian.org/debian bookworm-backports main" > /etc/apt/sources.list.d/backports.list
RUN apt update
RUN apt install -t bookworm-backports -y golang

COPY ./tools/buildutils/installbazel.sh /installbazel.sh
RUN /installbazel.sh && rm /installbazel.sh

Expand Down
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