amazon-web-services - Lambda 无法访问 KMS key

Question

当我运行我的 lambda 代码时，我收到以下错误:
The ciphertext refers to a customer master key that does not exist, does not exist in this region, or you are not allowed to access.
我主要关注 this使用 aws-sam-cli 创建堆栈，模板的相关部分在代码下方。

相关代码是:

const ssm = new AWS.SSM();
const param = {
    Name: "param1",
    WithDecryption: true
};
const secret = await ssm.getParameter(param).promise();

template.yaml 文件的相关部分是:

KeyAlias:
    Type: AWS::KMS::Alias
    Properties:
      AliasName: 'param1Key'
      TargetKeyId: !Ref Key
Key:
    Type: AWS::KMS::Key
    Properties:
      KeyPolicy:
        Id: default
        Statement:
        - Effect: Allow
          Principal:
            AWS: !Sub arn:aws:iam::${AWS::AccountId}:root
          Action:
          - 'kms:Create*'
          - 'kms:Encrypt'
          - 'kms:Describe*'
          - 'kms:Enable*'
          - 'kms:List*'
          - 'kms:Put*'
          - 'kms:Update*'
          - 'kms:Revoke*'
          - 'kms:Disable*'
          - 'kms:Get*'
          - 'kms:Delete*'
          - 'kms:ScheduleKeyDeletion'
          - 'kms:CancelKeyDeletion'
          Resource: '*'
          Sid: Allow root account all permissions except to decrypt the key
        Version: 2012-10-17

LambdaFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: ../
      Handler: app.lambda
      Runtime: nodejs8.10
      Policies:
      - DynamoDBReadPolicy:
          TableName: !Ref Table
      - KMSDecryptPolicy:
          KeyId: !Ref Key
      - Statement:
         - Action:
           - "ssm:GetParameter"
           Effect: Allow
           Resource: !Sub "arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/param1"

是否 KMSDecryptPolicy不允许使用 key ？我错过了什么？谢谢!

编辑:将模板更改为以下有效，但我真的很想使用 KMSDecryptPolicy如果可能，在 lambda 定义中。

LambdaFunction:
    Type: AWS::Serverless::Function
    Properties:
      CodeUri: ../
      Handler: app.lambda
      Runtime: nodejs8.10
      Policies:
      - DynamoDBReadPolicy:
          TableName: !Ref Table
      - KMSDecryptPolicy:
          KeyId: !Ref Key
      - Statement:
         - Action:
           - "ssm:GetParameter"
           Effect: Allow
           Resource: !Sub "arn:aws:ssm:${AWS::Region}:${AWS::AccountId}:parameter/param1"

Key:
    Type: AWS::KMS::Key
    Properties:
      KeyPolicy:
        Id: default
        Statement:
        - Effect: Allow
          Principal:
            AWS: !Sub arn:aws:iam::${AWS::AccountId}:root
          Action:
          - 'kms:Create*'
          - 'kms:Encrypt'
          - 'kms:Describe*'
          - 'kms:Enable*'
          - 'kms:List*'
          - 'kms:Put*'
          - 'kms:Update*'
          - 'kms:Revoke*'
          - 'kms:Disable*'
          - 'kms:Get*'
          - 'kms:Delete*'
          - 'kms:ScheduleKeyDeletion'
          - 'kms:CancelKeyDeletion'
          Resource: '*'
          Sid: Allow root account all permissions except to decrypt the key
        - Sid: 'Allow use of the key for decryption by the LambdaFunction'
          Effect: Allow
          Principal:
            AWS: !GetAtt LambdaFunctionRole.Arn
          Action:
          - 'kms:Decrypt'
          Resource: '*'        
        Version: 2012-10-17

Answer 1

问题本身包含了答案。变化是，它不仅在 lambda 角色中授予 KMS 权限(基于身份的方式)，还为 key 策略中的 lambda 角色授予权限(基于资源的方式)。

这是关于为什么会发生这种情况的 AWS 官方资源 - https://docs.aws.amazon.com/kms/latest/developerguide/iam-policies.html

根据这个

All KMS CMKs have a key policy, and you must use it to control access to a CMK. IAM policies by themselves are not sufficient to allow access to a CMK, though you can use them in combination with a CMK's key policy.