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fix: prevent zip-slip path traversal in OCI layer extraction #37

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fix: prevent zip-slip path traversal in OCI layer extraction #37

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11 changes: 11 additions & 0 deletions pkg/util/fs_util.go
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Original file line number Diff line number Diff line change
Expand Up @@ -396,6 +396,10 @@ func UnTar(r io.Reader, dest string) ([]string, error) {

func ExtractFile(dest string, hdr *tar.Header, cleanedName string, tr io.Reader) error {
path := filepath.Join(dest, cleanedName)
cleanRoot := filepath.Clean(dest) + string(filepath.Separator)
if !strings.HasPrefix(filepath.Clean(path)+string(filepath.Separator), cleanRoot) {
return fmt.Errorf("path traversal detected in tar entry %q escapes root", hdr.Name)
}
base := filepath.Base(path)
dir := filepath.Dir(path)
mode := hdr.FileInfo().Mode()
Expand Down Expand Up @@ -501,6 +505,13 @@ func ExtractFile(dest string, hdr *tar.Header, cleanedName string, tr io.Reader)
return errors.Wrapf(err, "error removing %s to make way for new symlink", hdr.Name)
}
}
// Guard: absolute symlink targets must resolve within dest
if filepath.IsAbs(hdr.Linkname) {
cleanTarget := filepath.Clean(hdr.Linkname) + string(filepath.Separator)
if !strings.HasPrefix(cleanTarget, cleanRoot) {
return fmt.Errorf("path traversal detected in symlink target %q escapes root", hdr.Linkname)
}
}
if err := filesystem.FS.Symlink(hdr.Linkname, path); err != nil {
return err
}
Expand Down