Merge pull request #413 from hashicorp/limited-decompressors-helper

v1: decompressors: add LimitedDecompressors helper

Author: shoenig

decompress.go

@@ -18,21 +18,24 @@ type Decompressor interface {
 	Decompress(dst, src string, dir bool, umask os.FileMode) error
 }
 
-// Decompressors is the mapping of extension to the Decompressor implementation
-// that will decompress that extension/type.
-var Decompressors map[string]Decompressor
-
-func init() {
-	tarDecompressor := new(TarDecompressor)
-	tbzDecompressor := new(TarBzip2Decompressor)
-	tgzDecompressor := new(TarGzipDecompressor)
-	txzDecompressor := new(TarXzDecompressor)
-	tzstDecompressor := new(TarZstdDecompressor)
+// LimitedDecompressors creates the set of Decompressors, but with each compressor configured
+// with the given filesLimit and/or fileSizeLimit where applicable.
+func LimitedDecompressors(filesLimit int, fileSizeLimit int64) map[string]Decompressor {
+	tarDecompressor := &TarDecompressor{FilesLimit: filesLimit, FileSizeLimit: fileSizeLimit}
+	tbzDecompressor := &TarBzip2Decompressor{FilesLimit: filesLimit, FileSizeLimit: fileSizeLimit}
+	tgzDecompressor := &TarGzipDecompressor{FilesLimit: filesLimit, FileSizeLimit: fileSizeLimit}
+	txzDecompressor := &TarXzDecompressor{FilesLimit: filesLimit, FileSizeLimit: fileSizeLimit}
+	tzstDecompressor := &TarZstdDecompressor{FilesLimit: filesLimit, FileSizeLimit: fileSizeLimit}
+	bzipDecompressor := &Bzip2Decompressor{FileSizeLimit: fileSizeLimit}
+	gzipDecompressor := &GzipDecompressor{FileSizeLimit: fileSizeLimit}
+	xzDecompressor := &XzDecompressor{FileSizeLimit: fileSizeLimit}
+	zipDecompressor := &ZipDecompressor{FilesLimit: filesLimit, FileSizeLimit: fileSizeLimit}
+	zstDecompressor := &ZstdDecompressor{FileSizeLimit: fileSizeLimit}
 
-	Decompressors = map[string]Decompressor{
-		"bz2":     new(Bzip2Decompressor),
-		"gz":      new(GzipDecompressor),
-		"xz":      new(XzDecompressor),
+	return map[string]Decompressor{
+		"bz2":     bzipDecompressor,
+		"gz":      gzipDecompressor,
+		"xz":      xzDecompressor,
 		"tar":     tarDecompressor,
 		"tar.bz2": tbzDecompressor,
 		"tar.gz":  tgzDecompressor,
@@ -42,11 +45,23 @@ func init() {
 		"tgz":     tgzDecompressor,
 		"txz":     txzDecompressor,
 		"tzst":    tzstDecompressor,
-		"zip":     new(ZipDecompressor),
-		"zst":     new(ZstdDecompressor),
+		"zip":     zipDecompressor,
+		"zst":     zstDecompressor,
 	}
 }
 
+const (
+	noFilesLimit    = 0
+	noFileSizeLimit = 0
+)
+
+// Decompressors is the mapping of extension to the Decompressor implementation
+// configured with default settings that will decompress that extension/type.
+//
+// Note: these decompressors by default do not limit the number of files or the
+// maximum file size created by the decompressed payload.
+var Decompressors = LimitedDecompressors(noFilesLimit, noFileSizeLimit)
+
 // containsDotDot checks if the filepath value v contains a ".." entry.
 // This will check filepath components by splitting along / or \. This
 // function is copied directly from the Go net/http implementation.

decompress_test.go

@@ -0,0 +1,50 @@
+package getter
+
+import (
+	"testing"
+)
+
+func TestLimitedDecompressors(t *testing.T) {
+	const (
+		maxFiles = 111
+		maxSize  = 222
+	)
+
+	checkFileSizeLimit := func(limit int64) {
+		if limit != maxSize {
+			t.Fatalf("expected FileSizeLimit of %d, got %d", maxSize, limit)
+		}
+	}
+
+	checkFilesLimit := func(limit int) {
+		if limit != maxFiles {
+			t.Fatalf("expected FilesLimit of %d, got %d", maxFiles, limit)
+		}
+	}
+
+	decompressors := LimitedDecompressors(maxFiles, maxSize)
+
+	checkFilesLimit(decompressors["tar"].(*TarDecompressor).FilesLimit)
+	checkFileSizeLimit(decompressors["tar"].(*TarDecompressor).FileSizeLimit)
+
+	checkFilesLimit(decompressors["tar.bz2"].(*TarBzip2Decompressor).FilesLimit)
+	checkFileSizeLimit(decompressors["tar.bz2"].(*TarBzip2Decompressor).FileSizeLimit)
+
+	checkFilesLimit(decompressors["tar.gz"].(*TarGzipDecompressor).FilesLimit)
+	checkFileSizeLimit(decompressors["tar.gz"].(*TarGzipDecompressor).FileSizeLimit)
+
+	checkFilesLimit(decompressors["tar.xz"].(*TarXzDecompressor).FilesLimit)
+	checkFileSizeLimit(decompressors["tar.xz"].(*TarXzDecompressor).FileSizeLimit)
+
+	checkFilesLimit(decompressors["tar.zst"].(*TarZstdDecompressor).FilesLimit)
+	checkFileSizeLimit(decompressors["tar.zst"].(*TarZstdDecompressor).FileSizeLimit)
+
+	checkFilesLimit(decompressors["zip"].(*ZipDecompressor).FilesLimit)
+	checkFileSizeLimit(decompressors["zip"].(*ZipDecompressor).FileSizeLimit)
+
+	// ones with file size limit only
+	checkFileSizeLimit(decompressors["bz2"].(*Bzip2Decompressor).FileSizeLimit)
+	checkFileSizeLimit(decompressors["gz"].(*GzipDecompressor).FileSizeLimit)
+	checkFileSizeLimit(decompressors["xz"].(*XzDecompressor).FileSizeLimit)
+	checkFileSizeLimit(decompressors["zst"].(*ZstdDecompressor).FileSizeLimit)
+}