runsc: validate mount targets

PiperOrigin-RevId: 382845950

1 files changed, 53 insertions, 0 deletions

diff --git a/runsc/specutils/safemount_test/safemount_test.go b/runsc/specutils/safemount_test/safemount_test.go
new file mode 100644
index 000000000..8820978c4
--- /dev/null
+++ b/runsc/specutils/safemount_test/safemount_test.go
@@ -0,0 +1,53 @@
+// Copyright 2021 The gVisor Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package safemount_test
+
+import (
+	"os"
+	"os/exec"
+	"syscall"
+	"testing"
+
+	"golang.org/x/sys/unix"
+	"gvisor.dev/gvisor/pkg/test/testutil"
+)
+
+func TestSafeMount(t *testing.T) {
+	// We run the actual tests in another process, as we need CAP_SYS_ADMIN to
+	// call mount(2). The new process runs in its own user and mount namespaces.
+	runner, err := testutil.FindFile("runsc/specutils/safemount_test/safemount_runner")
+	if err != nil {
+		t.Fatalf("failed to find test runner binary: %v", err)
+	}
+	cmd := exec.Command(runner, t.TempDir())
+	cmd.SysProcAttr = &unix.SysProcAttr{
+		Cloneflags: unix.CLONE_NEWNS | unix.CLONE_NEWUSER,
+		UidMappings: []syscall.SysProcIDMap{
+			{ContainerID: 0, HostID: os.Getuid(), Size: 1},
+		},
+		GidMappings: []syscall.SysProcIDMap{
+			{ContainerID: 0, HostID: os.Getgid(), Size: 1},
+		},
+		GidMappingsEnableSetgroups: false,
+		Credential: &syscall.Credential{
+			Uid: 0,
+			Gid: 0,
+		},
+	}
+	output, err := cmd.CombinedOutput()
+	if err != nil {
+		t.Fatalf("failed running %s with error: %v\ntest output:\n%s", cmd, err, output)
+	}
+}