如何从web.xml检索权限

Question

我想知道是否有更好的方法（没有反射）来获取特定URL和角色的java.security.Permissions。

例如：

 boolean canAccess = SecurityController.isAllowedToAccessUrl("/pages/confirmOrders.action", Collections.singletonList(new UserPrincipal("Dave")));

将使用以下约束（web.xml）：

<security-constraint>
 <web-resource-collection>
   <web-resource-name></web-resource-name>
   <url-pattern>/pages/confirmOrders.action</url-pattern>
 </web-resource-collection>
 <auth-constraint>
   <role-name>Dave</role-name>
 </auth-constraint>

我写的下面的代码效果很好。我不喜欢的是我必须使用反射从DelegatingPolicy.getInstance（）调用getContextPolicy并从ContextPolicy调用getPermissionsForRole。

import org.jboss.security.jacc.ContextPolicy;
import org.jboss.security.jacc.DelegatingPolicy;

import javax.security.jacc.PolicyConfigurationFactory;
import javax.security.jacc.PolicyContext;
import javax.security.jacc.PolicyContextException;
import javax.security.jacc.WebResourcePermission;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.security.Permissions;
import java.security.Principal;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

public class SecurityController {
  private static final Logger LOG  = Logger.getLogger(SecurityController.class.getName());

  static boolean isAllowedToAccessUrl(final String url, final List<Principal> principalRoles) {
    initializeConfigurationInService();

    boolean result = false;
    for (Principal principalRole : principalRoles) {
      try{
        final ContextPolicy contextPolicy = getContextPolicy();
        final Permissions permissions = getPermissionsFromContextPolicy(contextPolicy, principalRole.getName());
        result |= permissions.implies(new WebResourcePermission(url, new String[] {"GET","POST"}));
      }catch (Exception e){
        LOG.log(Level.SEVERE, "checkAllowed failed checking if : ", e);
      }
    }
    return result;
  }

  private static void initializeConfigurationInService() {
    try {
      final PolicyConfigurationFactory policyConfigurationFactory = PolicyConfigurationFactory.getPolicyConfigurationFactory();
      policyConfigurationFactory.getPolicyConfiguration(PolicyContext.getContextID(), false);
    } catch (PolicyContextException | ClassNotFoundException e) {
      LOG.log(Level.INFO, "initializeConfigurationInService", e);
    }
  }

  private static Permissions getPermissionsFromContextPolicy(ContextPolicy contextPolicy, String loginName) throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
    final Method getPermissionsForRole = contextPolicy.getClass().getDeclaredMethod("getPermissionsForRole", String.class);
    getPermissionsForRole.setAccessible(true);
    return (Permissions) getPermissionsForRole.invoke(contextPolicy, loginName);
  }


  private static ContextPolicy getContextPolicy() throws NoSuchMethodException, IllegalAccessException, InvocationTargetException {
    final DelegatingPolicy delegatingPolicy = DelegatingPolicy.getInstance();
    final Method getContextPolicy = delegatingPolicy.getClass().getDeclaredMethod("getContextPolicy", String.class);
    getContextPolicy.setAccessible(true);
    return (ContextPolicy) getContextPolicy.invoke(delegatingPolicy, PolicyContext.getContextID());
  }
}

我读了programmatically retrieve security constraints from web.xml，但发现它不是很有用。

任何评论，想法都非常受欢迎。谢谢！

Answer 1

感谢Uux的评论，我能够缩短我的代码并摆脱使用反射。我现在能够验证是否允许特定角色访问我的代码中的特定URL。

可行代码如下：

import javax.security.jacc.WebResourcePermission;
import java.security.CodeSource;
import java.security.Policy;
import java.security.Principal;
import java.security.ProtectionDomain;
import java.security.cert.Certificate;
import java.util.List;
import java.util.logging.Level;
import java.util.logging.Logger;

public class SecurityController {
  private static final Logger LOG = Logger.getLogger(SecurityController.class.getName());

  static boolean isAllowedToAccessUrl(final String url, final List<Principal> principalRoles) {
    try {
      final CodeSource codesource = new CodeSource(null, (Certificate[]) null);
      final Principal[] principals = principalRoles.toArray(new Principal[0]);
      final ProtectionDomain domain = new ProtectionDomain(codesource, null, null, principals);
      return Policy.getPolicy().implies(domain, (new WebResourcePermission(url, new String[] {"GET", "POST"})));
    } catch (Exception e) {
      LOG.log(Level.SEVERE, "checkAllowed failed checking if : ", e);
    }
    return false;
  }
}

Answer 2

Java EE 8中提供了类似的标准方法来执行'isAllowedToAccessUrl`功能。

boolean hasAccessToWebResource(String resource, String... methods)

检查调用者是否可以使用给定方法访问提供的“Web资源”，如Servlet规范的第13.8节所述。如果Web资源未受到保护（约束），或者受角色保护并且调用者具有该角色，则调用者可以访问。

见：SecurityContext#hasAccessToWebResource