发送带有多个值的 XACML 请求以由策略评估
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【中文标题】发送带有多个值的 XACML 请求以由策略评估【英文标题】:Sending XACML request with multiple values in bag to be evaluated by policy 【发布时间】:2019-07-04 10:53:46 【问题描述】:以下是针对中国墙的 XACML 策略,它使用stringAtLeastOneMemberOf
比较两个属性,看看它们是否包含相同的值列表。
即如果请求访问对象的主体具有标签[1, 4, 5]
,而对象具有标签[2, 3, 5]
,则访问将被拒绝,因为两者都包含5
。
中国墙政策
ALFA 代码
attribute subjectConflicts
id = "urn:oasis:names:tc:xacml:1.0:subject:subject-conflicts"
type = string
category = subjectCat
attribute resourceConflicts
id = "urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts"
type = string
category = resourceCat
namespace models
import Attributes.*
/*
*
* This policy implements the Chinese Wall model.
*
*/
policy ChineseWall
target clause resourceType=="calcert"
apply firstApplicable
/*
* Check subject is not in conflict with object OEMs and calibrators
*
* This rule will deny access is user.label contains at least 1 value that is also present
* in object.label
*/
rule noconflict
target clause actionId=="read" or actionId=="write"
condition stringAtLeastOneMemberOf(subjectConflicts, resourceConflicts)
deny
XACML 政策
<?xml version="1.0" encoding="UTF-8"?>
<!--This file was generated by the ALFA Plugin for Eclipse from Axiomatics AB (http://www.axiomatics.com).-->
<!--Any modification to this file will be lost upon recompilation of the source ALFA file-->
<xacml3:Policy xmlns:xacml3="urn:oasis:names:tc:xacml:3.0:core:schema:wd-17" PolicyId="http://axiomatics.com/alfa/identifier/models.ChineseWall" RuleCombiningAlgId="urn:oasis:names:tc:xacml:1.0:rule-combining-algorithm:first-applicable" Version="1.0">
<xacml3:Description>This policy implements the Chinese Wall model.</xacml3:Description>
<xacml3:PolicyDefaults>
<xacml3:XPathVersion>http://www.w3.org/TR/1999/REC-xpath-19991116</xacml3:XPathVersion>
</xacml3:PolicyDefaults>
<xacml3:Target>
<xacml3:AnyOf>
<xacml3:AllOf>
<xacml3:Match MatchId="urn:oasis:names:tc:xacml:1.0:function:string-equal">
<xacml3:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">calcert</xacml3:AttributeValue>
<xacml3:AttributeDesignator AttributeId="urn:oasis:names:tc:xacml:1.0:resource:resource-type" Category="urn:oasis:names:tc:xacml:3.0:attribute-category:resource" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="false" />
</xacml3:Match>
</xacml3:AllOf>
</xacml3:AnyOf>
</xacml3:Target>
<xacml3:Rule Effect="Deny" RuleId="models.ChineseWall.noconflict">
<xacml3:Description>Check subject is not in conflict with object OEMs and calibrators
This rule will deny access is user.label contains at least 1 value that is also present
in object.label</xacml3:Description>
<xacml3:Target>
<xacml3:AnyOf>
<xacml3:AllOf>
<xacml3:Match MatchId="urn:oasis:names:tc:xacml:1.0:function:string-equal">
<xacml3:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">read</xacml3:AttributeValue>
<xacml3:AttributeDesignator AttributeId="urn:oasis:names:tc:xacml:1.0:action:action-id" Category="urn:oasis:names:tc:xacml:3.0:attribute-category:action" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="false" />
</xacml3:Match>
</xacml3:AllOf>
<xacml3:AllOf>
<xacml3:Match MatchId="urn:oasis:names:tc:xacml:1.0:function:string-equal">
<xacml3:AttributeValue DataType="http://www.w3.org/2001/XMLSchema#string">write</xacml3:AttributeValue>
<xacml3:AttributeDesignator AttributeId="urn:oasis:names:tc:xacml:1.0:action:action-id" Category="urn:oasis:names:tc:xacml:3.0:attribute-category:action" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="false" />
</xacml3:Match>
</xacml3:AllOf>
</xacml3:AnyOf>
</xacml3:Target>
<xacml3:Condition>
<xacml3:Apply FunctionId="urn:oasis:names:tc:xacml:1.0:function:string-at-least-one-member-of">
<xacml3:AttributeDesignator AttributeId="urn:oasis:names:tc:xacml:1.0:subject:subject-conflicts" Category="urn:oasis:names:tc:xacml:1.0:subject-category:access-subject" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="false" />
<xacml3:AttributeDesignator AttributeId="urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts" Category="urn:oasis:names:tc:xacml:3.0:attribute-category:resource" DataType="http://www.w3.org/2001/XMLSchema#string" MustBePresent="false" />
</xacml3:Apply>
</xacml3:Condition>
</xacml3:Rule>
</xacml3:Policy>
政策执行点 (PEP) 代码
我正在使用Authzforce Core PDP for Java 来模拟 PDP,并按如下方式评估请求:
private DecisionRequest parseJSONAndBuildXACML(JSONObject obj)
DecisionRequestBuilder builder = server.pdpEngine.getEngine().newRequestBuilder(-1, -1);
/** Add Principle **/
// Principle ID
AttributeFqn principleID = AttributeFqns.newInstance(XACML_1_0_ACCESS_SUBJECT.value(), Optional.empty(), XacmlAttributeId.XACML_1_0_SUBJECT_ID.value());
AttributeBag<?> principleIDValue = Bags.singletonAttributeBag(StandardDatatypes.STRING, new StringValue("Principle" + obj.getJSONObject("principle").getString("id")));
builder.putNamedAttributeIfAbsent(principleID, principleIDValue);
// Principle Label
AttributeFqn principleLabel = AttributeFqns.newInstance(XACML_1_0_ACCESS_SUBJECT.value(), Optional.<String>empty(), XACML_1_0_SUBJECT_LABEL);
AttributeBag<?> principleLabelValue = Bags.singletonAttributeBag(StandardDatatypes.INTEGER, new IntegerValue(new MediumInteger(obj.getJSONObject("principle").getInt("label"))));
builder.putNamedAttributeIfAbsent(principleLabel, principleLabelValue);
// Principle Conflict Set
AttributeFqn principleConflicts = AttributeFqns.newInstance(XACML_1_0_ACCESS_SUBJECT.value(), Optional.empty(), XACML_1_0_SUBJECT_CONFLICTS);
Collection<StringValue> pconflicts = getStringListFromJsonArray(obj.getJSONObject("principle").getJSONArray("conflicts"));
AttributeBag<?> principleConflictsValue = Bags.newAttributeBag(StandardDatatypes.STRING, pconflicts);
//AttributeBag<?> principleConflictsValue = Bags.singletonAttributeBag(StandardDatatypes.STRING, new StringValue(obj.getJSONObject("principle").getString("conflicts")));
builder.putNamedAttributeIfAbsent(principleConflicts, principleConflictsValue);
// Object ID
AttributeFqn objectID = AttributeFqns.newInstance(XACML_3_0_RESOURCE.value(), Optional.empty(), XACML_1_0_RESOURCE_ID.value());
AttributeBag<?> objectIDValue = Bags.singletonAttributeBag(StandardDatatypes.STRING, new StringValue(obj.getJSONObject("object").getString("id")));
builder.putNamedAttributeIfAbsent(objectID, objectIDValue);
// Object Type
AttributeFqn objectType = AttributeFqns.newInstance(XACML_3_0_RESOURCE.value(), Optional.empty(), XACML_1_0_RESOURCE_TYPE);
AttributeBag<?> objectTypeValue = Bags.singletonAttributeBag(StandardDatatypes.STRING, new StringValue(obj.getJSONObject("object").getString("type")));
builder.putNamedAttributeIfAbsent(objectType, objectTypeValue);
// Object Label
AttributeFqn objectLabel = AttributeFqns.newInstance(XACML_3_0_RESOURCE.value(), Optional.<String>empty(), XACML_1_0_RESOURCE_LABEL);
AttributeBag<?> objectLabelValue = Bags.singletonAttributeBag(StandardDatatypes.INTEGER, new IntegerValue(new MediumInteger(obj.getJSONObject("object").getInt("label"))));
builder.putNamedAttributeIfAbsent(objectLabel, objectLabelValue);
// Object Conflict Set
AttributeFqn objectConflicts = AttributeFqns.newInstance(XACML_3_0_RESOURCE.value(), Optional.empty(), XACML_1_0_RESOURCE_CONFLICTS);
Collection<StringValue> oconflicts = getStringListFromJsonArray(obj.getJSONObject("object").getJSONArray("conflicts"));
AttributeBag<?> objectConflictsValue = Bags.newAttributeBag(StandardDatatypes.STRING, oconflicts);
//AttributeBag<?> objectConflictsValue = Bags.singletonAttributeBag(StandardDatatypes.STRING, new StringValue(obj.getJSONObject("object").getString("conflicts")));
builder.putNamedAttributeIfAbsent(objectConflicts, objectConflictsValue);
// Action
AttributeFqn action = AttributeFqns.newInstance(XACML_3_0_ACTION.value(), Optional.empty(), XacmlAttributeId.XACML_1_0_ACTION_ID.value());
AttributeBag<?> actionValue = Bags.singletonAttributeBag(StandardDatatypes.STRING, new StringValue(obj.getString("action")));
builder.putNamedAttributeIfAbsent(action, actionValue);
return builder.build(false);
在这种情况下,JSONObject
就是我将请求从客户端发送到 PDP 引擎的方式。其他策略有效,这里的问题是我正在向包发送一个字符串,即"[2, 4, 5]"
,但它总是导致NotApplicable
。是否有我应该在这里使用的列表类型来符合政策?
这是我发送的 JSON:
"principle":
"conflicts": [
"1",
"2",
"10"
],
"id": "Principle 1",
"label": 3
,
"action": "read",
"object":
"conflicts": [
"4",
"5",
"9"
],
"id": "Object 1",
"label": 2,
"type": "calcert"
挑战
更准确地说,冲突集的 Authzforce 的 Java 代码中的 JSON 输出将是一个字符串,即"[2,3,5]"
,而我认为这需要是另一种格式(因为它总是导致 NotApplicable),但这是我的问题。
【问题讨论】:
你能告诉我们ALFA的来源吗? @DavidBrossard 我已经更新了 OP 以包含 ALFA! 【参考方案1】:您需要在代码中修复至少 2 个问题:
由于您想要一个字符串列表中的包,可能不止一个,您必须使用更通用的 Bags.newAttributeBag(...)
- 第二个参数必须是您的实际字符串列表 - 而不是强>Bags.singletonAttributeBag()
。只有这样,PDP 才会将其视为多个 String 类型的 AttributeValue。
您使用了相同的主题属性XACML_1_0_SUBJECT_CONFLICTS
两次,第二次是 objectConflicts 属性,所以我猜这是错误的,需要修复,因为这必须是资源改为属性urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts
。
【讨论】:
我正在使用AttributeBag<?> principleConflictsValue = Bags.newAttributeBag(StandardDatatypes.STRING, conflicts);
,其中conflicts
是来自JSON 的Collection<String>
,其中JSON 是["1", "2", "3"]
,这仍然会导致拒绝。我是否正确使用了属性包?还是来自 JSON 的输入有问题?
对于第一个问题,您必须对所有多值属性使用Bags.newAttributeBag(...)
,即principalConflictsValue 和objectConflictsValue(可能你错过了第二个)。 第二个问题怎么样,你解决了吗?我认为你的问题没有解决。请相应地编辑您的问题或将我们指向完整的最新代码(例如在 github 上),以便我们可以跟踪您的更改/修复,否则很难检查和/或重现。
好的。您现在使用固定代码做出的决定是什么? Deny 或 NotApplicable? 您仍然在 OP 中说 Deny,但在您对 David Brossard 的回答中说 NotApplicable。只想确认一下。并且要小心 'first-applicable' 算法;在您的策略中,您仅将一个规则与拒绝效果结合在一起,因此您将获得拒绝(如果规则评估为拒绝)或 NotApplicable(默认情况下)作为最终结果,仅此而已(或在错误的情况下不确定,但这是边缘情况)。更多信息见 XACML 规范附录 C.8。
抱歉给您带来了困惑,我目前正在获取 NotApplicable。
在这种情况下,很抱歉... 它按预期工作!。实际上,对于这样的请求和策略,策略的目标是 Match(calcert
资源类型),但是:规则的目标是 Match(read
操作)并且 Condition 为 False(subject-conflicts
和 resource-conflicts
没有共同的字符串),因此规则不适用(参见 XACML §7.11),因此 first-applicable
算法导致 NotApplicable
(参见 XACML §C. 8)。如果你期待别的东西,你应该改变组合算法(例如permit-unless-deny
,如果你想要 Permit 代替)。【参考方案2】:
首先,您必须了解 XACML 中的所有属性默认情况下都是值包。因此,urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts
是一个可以包含 0(零)、1 或更多值的包。但它仍然是一个包。 ALFA / XACML 中的任何属性都是如此。这意味着当你写:
target clause resourceType=="calcert"
您实际上是在说 如果至少有一个值 resourceType
等于 calcert
...
在您的情况下,您正在使用一个名为stringAtLeastOneMemberOf
的函数。此函数接收两个字符串类型的包,如果第一个包包含第二个包中存在的至少一个值,则返回 true。它类似于stringIsIn
,只是后者接受一个原子字符串和一个字符串包。您必须写 stringIsIn(stringOneAndOnly(a), b)
才能使其正常工作。属性 a 也必须是一个包含单个值的包。
在您的情况下,您有 2 个可以多值的属性(subjectConflicts
和 resourceConflicts
)。这意味着如果你“打印”它们,你会看到类似 ["a", "b", "c", "a"] 的东西。这是一袋价值观。顺便说一下,包可以包含重复项。并且顺序无关紧要(属性的顺序或属性值的顺序)。
现在,您要做的是发送一个表示此内容的 XACML JSON 请求。生成的 JSON 应如下所示:
示例 JSON 请求
在这个例子中,两个属性都是多值的:
"Request":
"Resource":[
"Attribute":[
"AttributeId":"urn:oasis:names:tc:xacml:1.0:resource:resource-type",
"Value":"calcert"
,
"AttributeId":"urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts",
"Value":[
"4",
"5",
"6"
]
]
],
"Action":[
"Attribute":[
"AttributeId":"urn:oasis:names:tc:xacml:1.0:action:action-id",
"Value":"read"
]
],
"AccessSubject":[
"Attribute":[
"AttributeId":"urn:oasis:names:tc:xacml:1.0:subject:subject-conflicts",
"Value":[
"1",
"2",
"3"
]
]
]
请求也可以写成
"Request":
"Resource":[
"Attribute":[
"AttributeId":"urn:oasis:names:tc:xacml:1.0:resource:resource-type",
"Value":"calcert"
,
"AttributeId":"urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts",
"Value":"4"
,
"AttributeId":"urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts",
"Value":"5"
,
"AttributeId":"urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts",
"Value":"6"
]
],
"Action":[
"Attribute":[
"AttributeId":"urn:oasis:names:tc:xacml:1.0:action:action-id",
"Value":"read"
]
],
"AccessSubject":[
"Attribute":[
"AttributeId":"urn:oasis:names:tc:xacml:1.0:subject:subject-conflicts",
"Value":"1"
,
"AttributeId":"urn:oasis:names:tc:xacml:1.0:subject:subject-conflicts",
"Value":"2"
,
"AttributeId":"urn:oasis:names:tc:xacml:1.0:subject:subject-conflicts",
"Value":"3"
]
]
XACML JSON 响应示例
"Response":[
"Decision":"NotApplicable"
]
为请求/响应找到合适的 SDK
在您的代码中,您使用 AuthZForce 的 PEP SDK。 Cyril 在他的另一个回答中指出了主要错误:
AttributeBag<?> objectConflictsValue = Bags.singletonAttributeBag(StandardDatatypes.STRING, new StringValue(obj.getJSONObject("object").getString("conflicts")));
问题是您要在 XACML 包内的单个值中添加冲突 ["1",...] 的整个字符串表示形式,而不是单独添加每个部分。
在我的示例中,我使用了自己的Java JSON PEP SDK。代码如下所示:
将每个值逐一相加:
resource.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts", "4"));
resource.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts", "5"));
resource.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts", "6"));
或添加为值数组:
resource.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts", new String[]"4","5","6"));
完整代码
package io.xacml.pep.json.so;
import com.fasterxml.jackson.databind.ObjectMapper;
import io.xacml.json.model.Attribute;
import io.xacml.json.model.Category;
import io.xacml.json.model.Request;
import io.xacml.json.model.Response;
import io.xacml.json.model.Result;
import io.xacml.pep.json.client.AuthZClient;
import io.xacml.pep.json.client.ClientConfiguration;
import io.xacml.pep.json.client.DefaultClientConfiguration;
import io.xacml.pep.json.client.jaxrs.JaxRsAuthZClient;
import lombok.extern.slf4j.Slf4j;
/**
* This class contains sample code using JAX-RS to invoke a Policy Decision Point.
* It supports both the JSON Profile of XACML 1.0 (where the response could be either an Object or
* an Array) and the JSON Profile of XACML 1.1 (where the response is always an array - to simplify
* things)
*
* @author djob
*/
@Slf4j
public class Example
public static void main(String[] args)
ObjectMapper mapper = new ObjectMapper();
ClientConfiguration clientConfiguration = DefaultClientConfiguration.builder()
.pdpUrl("http://djob-hp:8080")
.username("ads-user")
.password("secret")
.build();
// Add user attributes
Category subject = new Category();
subject.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:subject:subject-conflicts", "1"));
subject.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:subject:subject-conflicts", "2"));
subject.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:subject:subject-conflicts", "3"));
// Add action attributes - if any
Category action = new Category();
action.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:action:action-id", "read"));
// Add user attributes
Category resource = new Category();
resource.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:resource:resource-type", "calcert"));
resource.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts", "4"));
resource.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts", "5"));
resource.addAttribute(new Attribute("urn:oasis:names:tc:xacml:1.0:resource:resource-conflicts", "6"));
Request authZRequest = new Request();
authZRequest.addAccessSubjectCategory(subject);
authZRequest.addActionCategory(action);
authZRequest.addResourceCategory(resource);
AuthZClient authZClient = new JaxRsAuthZClient(clientConfiguration, mapper);
Response authZResponse = authZClient.makeAuthorizationRequest(authZRequest);
for (Result r : authZResponse.getResults())
log.debug(r.getDecision().name());
【讨论】:
感谢您的详细解答!但是,使用我拥有的代码(因此无需进行重大更改),如何使用包将冲突列表添加为属性?如果您看到我对 Cyrils 回答的评论,我会在将列表添加到包时检索值,如下所示:Bag(elementType='http://www.w3.org/2001/XMLSchema#string', elements=[1, 2, 10], causeForEmpty=null)
。但我仍然收到DENY/NOT_APPLICABLE
你是被拒绝还是不适用?
不适用。以上是关于发送带有多个值的 XACML 请求以由策略评估的主要内容,如果未能解决你的问题,请参考以下文章