test(downscope): add integration tests for token downscoping with Cre…

…dential Access Boundaries (#1124)

Testing the code present in `oauth2/google/downscope`.  I also caught a typo in the comments of a previous push- given that I only needed to add a single space, I bundled that change into this PR.

integration-tests/downscope/downscope_test.go

@@ -0,0 +1,145 @@
+// Copyright 2021 Google LLC.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package downscope
+
+import (
+	"context"
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"log"
+	"os"
+	"testing"
+	"time"
+
+	"google.golang.org/api/option"
+
+	"golang.org/x/oauth2"
+	"golang.org/x/oauth2/google"
+	"golang.org/x/oauth2/google/downscope"
+	storage "google.golang.org/api/storage/v1"
+	"google.golang.org/api/transport"
+)
+
+const (
+	rootTokenScope        = "https://www.googleapis.com/auth/cloud-platform"
+	envServiceAccountFile = "GCLOUD_TESTS_GOLANG_KEY"
+	object1               = "cab-first-c45wknuy.txt"
+	object2               = "cab-second-c45wknuy.txt"
+	bucket                = "dulcet-port-762"
+)
+
+var (
+	rootCredential *google.Credentials
+)
+
+// TestMain contains all of the setup code that needs to be run once before any of the tests are run
+func TestMain(m *testing.M) {
+	flag.Parse()
+	if testing.Short() {
+		// This line runs all of our individual tests
+		os.Exit(m.Run())
+	}
+	ctx := context.Background()
+	credentialFileName := os.Getenv(envServiceAccountFile)
+
+	var err error
+	rootCredential, err = transport.Creds(ctx, option.WithCredentialsFile(credentialFileName), option.WithScopes(rootTokenScope))
+
+	if err != nil {
+		log.Fatalf("failed to construct root credential: %v", err)
+	}
+
+	// This line runs all of our individual tests
+	os.Exit(m.Run())
+
+}
+
+// downscopeTest holds the parameters necessary for running a test of the token downscoping capabilities implemented in `oauth2/google/downscope`
+type downscopeTest struct {
+	name                 string
+	availableResource    string
+	availablePermissions []string
+	condition            downscope.AvailabilityCondition
+	objectName           string
+	rootSource           oauth2.TokenSource
+	expectError          bool
+}
+
+func TestDownscopedToken(t *testing.T) {
+	if testing.Short() {
+		t.Skip("skipping integration test")
+	}
+
+	var downscopeTests = []downscopeTest{
+		{
+			name:                 "successfulDownscopedRead",
+			availableResource:    "//storage.googleapis.com/projects/_/buckets/" + bucket,
+			availablePermissions: []string{"inRole:roles/storage.objectViewer"},
+			condition: downscope.AvailabilityCondition{
+				Expression: "resource.name.startsWith('projects/_/buckets/" + bucket + "/objects/" + object1 + "')",
+			},
+			rootSource:  rootCredential.TokenSource,
+			objectName:  object1,
+			expectError: false,
+		},
+		{
+			name:                 "readWithoutPermission",
+			availableResource:    "//storage.googleapis.com/projects/_/buckets/" + bucket,
+			availablePermissions: []string{"inRole:roles/storage.objectViewer"},
+			condition: downscope.AvailabilityCondition{
+				Expression: "resource.name.startsWith('projects/_/buckets/" + bucket + "/objects/" + object1 + "')",
+			},
+			rootSource:  rootCredential.TokenSource,
+			objectName:  object2,
+			expectError: true,
+		},
+	}
+
+	for _, tt := range downscopeTests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := downscopeQuery(t, tt)
+			// If a test isn't supposed to fail, it shouldn't fail.
+			if !tt.expectError && err != nil {
+				t.Errorf("test case %v should have succeeded, but instead returned %v", tt.name, err)
+			} else if tt.expectError && err == nil { // If a test is supposed to fail, it should return a non-nil error.
+				t.Errorf(" test case %v should have returned an error, but instead returned nil", tt.name)
+			}
+		})
+	}
+}
+
+// I'm not sure what I should name this according to convention.
+func downscopeQuery(t *testing.T, tt downscopeTest) error {
+	t.Helper()
+	ctx := context.Background()
+
+	// Initializes an accessBoundary
+	var AccessBoundaryRules []downscope.AccessBoundaryRule
+	AccessBoundaryRules = append(AccessBoundaryRules, downscope.AccessBoundaryRule{AvailableResource: tt.availableResource, AvailablePermissions: tt.availablePermissions, Condition: &tt.condition})
+
+	downscopedTokenSource, err := downscope.NewTokenSource(context.Background(), downscope.DownscopingConfig{RootSource: tt.rootSource, Rules: AccessBoundaryRules})
+	if err != nil {
+		return fmt.Errorf("failed to create the initial token source: %v", err)
+	}
+	downscopedTokenSource = oauth2.ReuseTokenSource(nil, downscopedTokenSource)
+
+	ctx, cancel := context.WithTimeout(ctx, time.Second*30)
+	defer cancel()
+	storageService, err := storage.NewService(ctx, option.WithTokenSource(downscopedTokenSource))
+	if err != nil {
+		return fmt.Errorf("failed to create the storage service: %v", err)
+	}
+	resp, err := storageService.Objects.Get(bucket, tt.objectName).Download()
+	if err != nil {
+		return fmt.Errorf("failed to retrieve object from GCP project with error: %v", err)
+	}
+	defer resp.Body.Close()
+	_, err = ioutil.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("ioutil.ReadAll: %v", err)
+	}
+	return nil
+}

integration-tests/downscope/setup.sh

@@ -0,0 +1,81 @@
+#!/bin/bash
+
+# Copyright 2021 Google LLC.
+# Use of this source code is governed by a BSD-style
+# license that can be found in the LICENSE file.
+
+
+# This script is used to generate the project configurations needed to
+# end-to-end test Downscoping with Credential Access Boundaries in the Auth
+# library. This script only needs to be run once.
+#
+# In order to run this script, you need to fill in the project_id and
+# service_account_email variables. 
+#
+# If an argument is provided, the script will use the provided argument
+# as the bucket name.  Otherwise, it will create a new bucket.
+#
+# This script needs to be run once. It will do the following:
+# 1. Sets the current project to the one specified.
+# 2. If no bucket name was provided, creates a GCS bucket in the specified project.
+# 3. Gives the specified service account the objectAdmin role for this bucket.
+# 4. Creates two text files to be uploaded to the created bucket.
+# 5. Uploads both text files.
+# 6. Prints out the identifiers (bucket ID, first object ID, second object ID)
+#    to be used in the accompanying tests. 
+# 7. Deletes the created text files in the current directory. 
+# 
+# The same service account used for this setup script should be used for
+# the integration tests.
+#
+# It is safe to run the setup script again. A new bucket is created along with
+# new objects. If run multiple times, it is advisable to delete
+# unused buckets. 
+
+suffix=""
+
+function generate_random_string () {
+  local valid_chars=abcdefghijklmnopqrstuvwxyz0123456789
+  for i in {1..8} ; do
+    suffix+="${valid_chars:RANDOM%${#valid_chars}:1}"
+    done
+}
+
+generate_random_string
+
+first_object="cab-first-"${suffix}.txt
+second_object="cab-second-"${suffix}.txt
+
+# Fill in.
+project_id="dulcet-port-762"
+service_account_email="[email protected]"
+
+gcloud config set project ${project_id}
+
+if (( $# != 1 ))
+then
+	# Create the GCS bucket.
+	bucket_id="cab-int-bucket-"${suffix}
+	gsutil mb -b on -l us-east1 gs://${bucket_id}  
+else
+	bucket_id="$1"
+fi
+
+# Give the specified service account the objectAdmin role for this bucket.
+gsutil iam ch serviceAccount:${service_account_email}:objectAdmin gs://${bucket_id}
+
+# Create both objects.
+echo "first" >> ${first_object}
+echo "second" >> ${second_object}
+
+# Upload the created objects to the bucket.
+gsutil cp ${first_object} gs://${bucket_id}
+gsutil cp ${second_object} gs://${bucket_id}
+
+echo "Bucket ID: "${bucket_id}
+echo "First object ID: "${first_object}
+echo "Second object ID: "${second_object}
+
+# Cleanup
+rm ${first_object}
+rm ${second_object}

integration-tests/impersonate/impersonate_test.go

@@ -15,12 +15,11 @@ import (
 	"time"
 
 	"google.golang.org/api/option"
-
 	"google.golang.org/api/storage/v1"
 )
 
 var (
-	// envReaderCredentialFile points to a service accountthat is a "Service
+	// envReaderCredentialFile points to a service account that is a "Service
 	// Account Token Creator" on envReaderSA.
 	envBaseSACredentialFile = "API_GO_CLIENT_IMPERSONATE_BASE"
 	// envUserCredentialFile points to a user credential that is a "Service