feat(auth): Introduce Regional Access Boundaries for GoogleCredentials (#12787)

Migrates RAB changes from the older repo ->
https://github.com/googleapis/google-auth-library-java/tree/feat-tb-sa

Author: vverman

google-auth-library-java/oauth2_http/java/com/google/auth/oauth2/ComputeEngineCredentials.java

@@ -41,6 +41,7 @@
 import com.google.api.client.http.HttpStatusCodes;
 import com.google.api.client.json.JsonObjectParser;
 import com.google.api.client.util.GenericData;
+import com.google.api.core.InternalApi;
 import com.google.auth.CredentialTypeForMetrics;
 import com.google.auth.Credentials;
 import com.google.auth.Retryable;
@@ -80,7 +81,7 @@
  * <p>These credentials use the IAM API to sign data. See {@link #sign(byte[])} for more details.
  */
 public class ComputeEngineCredentials extends GoogleCredentials
-    implements ServiceAccountSigner, IdTokenProvider {
+    implements ServiceAccountSigner, IdTokenProvider, RegionalAccessBoundaryProvider {
 
   static final String METADATA_RESPONSE_EMPTY_CONTENT_ERROR_MESSAGE =
       "Empty content from metadata token server request.";
@@ -454,7 +455,6 @@ public AccessToken refreshAccessToken() throws IOException {
     int expiresInSeconds =
         OAuth2Utils.validateInt32(responseData, "expires_in", PARSE_ERROR_PREFIX);
     long expiresAtMilliseconds = clock.currentTimeMillis() + expiresInSeconds * 1000;
-
     return new AccessToken(accessToken, new Date(expiresAtMilliseconds));
   }
 
@@ -779,6 +779,11 @@ public static Builder newBuilder() {
    *
    * @throws RuntimeException if the default service account cannot be read
    */
+  @Override
+  HttpTransportFactory getTransportFactory() {
+    return transportFactory;
+  }
+
   @Override
   // todo(#314) getAccount should not throw a RuntimeException
   public String getAccount() {
@@ -792,6 +797,13 @@ public String getAccount() {
     return principal;
   }
 
+  @InternalApi
+  @Override
+  public String getRegionalAccessBoundaryUrl() throws IOException {
+    return String.format(
+        OAuth2Utils.IAM_CREDENTIALS_ALLOWED_LOCATIONS_URL_FORMAT_SERVICE_ACCOUNT, getAccount());
+  }
+
   /**
    * Signs the provided bytes using the private key associated with the service account.
    *

google-auth-library-java/oauth2_http/java/com/google/auth/oauth2/ExternalAccountAuthorizedUserCredentials.java

@@ -31,7 +31,9 @@
 
 package com.google.auth.oauth2;
 
+import static com.google.auth.oauth2.OAuth2Utils.IAM_CREDENTIALS_ALLOWED_LOCATIONS_URL_FORMAT_WORKFORCE_POOL;
 import static com.google.auth.oauth2.OAuth2Utils.JSON_FACTORY;
+import static com.google.auth.oauth2.OAuth2Utils.WORKFORCE_AUDIENCE_PATTERN;
 
 import com.google.api.client.http.GenericUrl;
 import com.google.api.client.http.HttpHeaders;
@@ -43,6 +45,7 @@
 import com.google.api.client.json.JsonObjectParser;
 import com.google.api.client.util.GenericData;
 import com.google.api.client.util.Preconditions;
+import com.google.api.core.InternalApi;
 import com.google.auth.http.HttpTransportFactory;
 import com.google.common.base.MoreObjects;
 import com.google.common.io.BaseEncoding;
@@ -54,6 +57,7 @@
 import java.util.Date;
 import java.util.Map;
 import java.util.Objects;
+import java.util.regex.Matcher;
 import javax.annotation.Nullable;
 
 /**
@@ -74,7 +78,8 @@
  * }
  * </pre>
  */
-public class ExternalAccountAuthorizedUserCredentials extends GoogleCredentials {
+public class ExternalAccountAuthorizedUserCredentials extends GoogleCredentials
+    implements RegionalAccessBoundaryProvider {
   private static final LoggerProvider LOGGER_PROVIDER =
       LoggerProvider.forClazz(ExternalAccountAuthorizedUserCredentials.class);
 
@@ -229,6 +234,24 @@ public AccessToken refreshAccessToken() throws IOException {
         .build();
   }
 
+  @InternalApi
+  @Override
+  public String getRegionalAccessBoundaryUrl() throws IOException {
+    Matcher matcher = WORKFORCE_AUDIENCE_PATTERN.matcher(getAudience());
+    if (!matcher.matches()) {
+      throw new IllegalStateException(
+          "The provided audience is not in the correct format for a workforce pool. "
+              + "Refer: https://docs.cloud.google.com/iam/docs/principal-identifiers");
+    }
+    String poolId = matcher.group("pool");
+    return String.format(IAM_CREDENTIALS_ALLOWED_LOCATIONS_URL_FORMAT_WORKFORCE_POOL, poolId);
+  }
+
+  @Override
+  HttpTransportFactory getTransportFactory() {
+    return transportFactory;
+  }
+
   @Nullable
   public String getAudience() {
     return audience;

google-auth-library-java/oauth2_http/java/com/google/auth/oauth2/ExternalAccountCredentials.java

@@ -31,6 +31,8 @@
 
 package com.google.auth.oauth2;
 
+import static com.google.auth.oauth2.OAuth2Utils.WORKFORCE_AUDIENCE_PATTERN;
+import static com.google.auth.oauth2.OAuth2Utils.WORKLOAD_AUDIENCE_PATTERN;
 import static com.google.common.base.Preconditions.checkNotNull;
 
 import com.google.api.client.http.HttpHeaders;
@@ -54,6 +56,7 @@
 import java.util.Locale;
 import java.util.Map;
 import java.util.concurrent.Executor;
+import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import javax.annotation.Nullable;
 
@@ -63,7 +66,8 @@
  * <p>Handles initializing external credentials, calls to the Security Token Service, and service
  * account impersonation.
  */
-public abstract class ExternalAccountCredentials extends GoogleCredentials {
+public abstract class ExternalAccountCredentials extends GoogleCredentials
+    implements RegionalAccessBoundaryProvider {
 
   private static final long serialVersionUID = 8049126194174465023L;
 
@@ -577,6 +581,11 @@ protected AccessToken exchangeExternalCredentialForAccessToken(
    */
   public abstract String retrieveSubjectToken() throws IOException;
 
+  @Override
+  HttpTransportFactory getTransportFactory() {
+    return transportFactory;
+  }
+
   public String getAudience() {
     return audience;
   }
@@ -620,6 +629,37 @@ public String getServiceAccountEmail() {
     return ImpersonatedCredentials.extractTargetPrincipal(serviceAccountImpersonationUrl);
   }
 
+  @InternalApi
+  @Override
+  public String getRegionalAccessBoundaryUrl() throws IOException {
+    if (getServiceAccountEmail() != null) {
+      return String.format(
+          OAuth2Utils.IAM_CREDENTIALS_ALLOWED_LOCATIONS_URL_FORMAT_SERVICE_ACCOUNT,
+          getServiceAccountEmail());
+    }
+
+    Matcher workforceMatcher = WORKFORCE_AUDIENCE_PATTERN.matcher(getAudience());
+    if (workforceMatcher.matches()) {
+      String poolId = workforceMatcher.group("pool");
+      return String.format(
+          OAuth2Utils.IAM_CREDENTIALS_ALLOWED_LOCATIONS_URL_FORMAT_WORKFORCE_POOL, poolId);
+    }
+
+    Matcher workloadMatcher = WORKLOAD_AUDIENCE_PATTERN.matcher(getAudience());
+    if (workloadMatcher.matches()) {
+      String projectNumber = workloadMatcher.group("project");
+      String poolId = workloadMatcher.group("pool");
+      return String.format(
+          OAuth2Utils.IAM_CREDENTIALS_ALLOWED_LOCATIONS_URL_FORMAT_WORKLOAD_POOL,
+          projectNumber,
+          poolId);
+    }
+
+    throw new IllegalStateException(
+        "The provided audience is not in a valid format for either a workload identity pool or a workforce pool."
+            + " Refer: https://docs.cloud.google.com/iam/docs/principal-identifiers");
+  }
+
   @Nullable
   public String getClientId() {
     return clientId;