cli/context/store: cap tls file size on zip import

`io.ReadAll(f)` on the decompressed tls/* entries was unbounded, so a
zip whose compressed archive is within the 10 MiB outer cap could still
decompress to multi-gigabyte TLS files and OOM the CLI. The meta.json
branch right above already wraps its reader in limitedReader, this just
mirrors it for the tls branch.

Also fast-fails on the advertised UncompressedSize64 before calling
zf.Open, so a well-formed zip bomb is rejected without any decompression
at all. limitedReader still guards the stream in case the header lies.

Fixes #6917

Signed-off-by: texasich <texasich@users.noreply.github.com>

Author: texasich

cli/context/store/store.go

@@ -474,11 +474,18 @@ func importZip(name string, s Writer, reader io.Reader) error {
 			}
 			importedMetaFile = true
 		} else if strings.HasPrefix(zf.Name, "tls/") {
+			// Reject entries whose advertised uncompressed size exceeds
+			// the per-file cap without decompressing, to avoid allocating
+			// gigabytes for a zip bomb (see #6917).
+			if zf.UncompressedSize64 > uint64(maxAllowedFileSizeToImport) {
+				return invalidParameter(fmt.Errorf("%s: tls file exceeds maximum allowed size", zf.Name))
+			}
 			f, err := zf.Open()
 			if err != nil {
 				return err
 			}
-			data, err := io.ReadAll(f)
+			// Defense in depth in case the zip header is spoofed.
+			data, err := io.ReadAll(&limitedReader{R: f, N: maxAllowedFileSizeToImport})
 			defer f.Close()
 			if err != nil {
 				return err

cli/context/store/store_test.go

@@ -211,6 +211,41 @@ func TestImportZip(t *testing.T) {
 	assert.NilError(t, err)
 }
 
+// TestImportZipTLSTooLarge verifies that a TLS entry whose uncompressed
+// size exceeds the per-file limit is rejected instead of being read into
+// memory unbounded (zip-bomb protection, see issue #6917).
+func TestImportZipTLSTooLarge(t *testing.T) {
+	meta, err := json.Marshal(Metadata{
+		Endpoints: map[string]any{
+			"ep1": endpoint{Foo: "bar"},
+		},
+		Metadata: context{Bar: "baz"},
+		Name:     "source",
+	})
+	assert.NilError(t, err)
+
+	buf := new(bytes.Buffer)
+	w := zip.NewWriter(buf)
+
+	mf, err := w.Create("meta.json")
+	assert.NilError(t, err)
+	_, err = mf.Write(meta)
+	assert.NilError(t, err)
+
+	tf, err := w.Create(path.Join("tls", "docker", "ca.pem"))
+	assert.NilError(t, err)
+	// Write well over the per-file cap; zeros compress to a tiny archive
+	// so the outer archive-size cap is not hit first.
+	oversized := make([]byte, 2*maxAllowedFileSizeToImport)
+	_, err = tf.Write(oversized)
+	assert.NilError(t, err)
+	assert.NilError(t, w.Close())
+
+	s := New(t.TempDir(), testCfg)
+	err = Import("zipBomb", s, bytes.NewReader(buf.Bytes()))
+	assert.ErrorContains(t, err, "tls file exceeds maximum allowed size")
+}
+
 func TestImportZipInvalid(t *testing.T) {
 	testDir := t.TempDir()
 	zf := path.Join(testDir, "test.zip")