S3 存储桶策略限制对单个文件夹的访问

Question

我有一个被多个 Lambda 访问的 S3 存储桶。我想限制对单个文件夹的访问，以便只有一个 Lambda 可以访问它。

我有以下创建所有资源的 Cloud Formation 模板，但我无法获得正确的存储桶策略条件。当我的 Lambda 执行角色被指定为例外时，它会限制对文件夹的访问，但不会授予对我的 Lambda 的访问权限。为什么下面的模板不起作用？

  ExampleBucket:
    Type: AWS::S3::Bucket
    Properties:
      BucketName: !Sub '${AWS::StackName}-${AWS::AccountId}-example-bucket'

  ExampleBucketPolicy:
    Type: 'AWS::S3::BucketPolicy'
    Properties:
      Bucket: !Ref ExampleBucket
      PolicyDocument:
        Version: 2012-10-17
        Statement:
          - Action:
              - 's3:*'
            Effect: Deny
            Resource:
              - !Sub arn:aws:s3:::${ExampleBucket}/example-folder/
              - !Sub arn:aws:s3:::${ExampleBucket}/example-folder/*
            Principal: '*'
            Condition:
              ArnNotEquals:
                aws:SourceArn:
                  - !GetAtt LambdaExecutionRole.Arn

  LambdaFunction:
    Type: AWS::Serverless::Function
    Properties:
      FunctionName: !Sub ${AWS::StackName}-handler
      CodeUri: ./src
      Handler: index.handler
      Role: !GetAtt LambdaExecutionRole.Arn
      Runtime: nodejs12.x

  LambdaExecutionRole:
    Type: AWS::IAM::Role    
    Properties:
      AssumeRolePolicyDocument:
        Statement:
        - Action:
          - sts:AssumeRole
          Effect: Allow
          Principal:
            Service:
            - lambda.amazonaws.com
      ManagedPolicyArns:
      - arn:aws:iam::aws:policy/service-role/AWSLambdaBasicExecutionRole
      - arn:aws:iam::aws:policy/AWSXrayWriteOnlyAccess
      Policies:
        - PolicyName: !Sub ${AWS::StackName}
          PolicyDocument:
            Statement:
              - Action:
                - s3:GetObject
                - s3:ListBucket
                - s3:PutObject
                Effect: Allow
                Resource: 
                  - !Sub arn:aws:s3:::${ExampleBucket}
                  - !Sub arn:aws:s3:::${ExampleBucket}/*
              - Action: 
                - lambda:InvokeFunction
                Effect: Allow
                Resource: '*'

我收到以下错误：“StoreDB 函数错误：putStoreObject，访问密钥：example-folder/example-file，AWS S3 消息：拒绝访问”

Answer 1

根据 OP 的评论，从 aws:SourceArn 更改为 aws:PrincipalArn 有效。