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fix(sns): for SSE topics, add KMS permissions in grantPublish #32794

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fix(sns): for SSE topics, add KMS permissions in grantPublish #32794

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6 changes: 3 additions & 3 deletions ...-cdk-testing/framework-integ/test/aws-sns/test/integ.sns.js.snapshot/SNSInteg.assets.json
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50 changes: 43 additions & 7 deletions ...dk-testing/framework-integ/test/aws-sns/test/integ.sns.js.snapshot/SNSInteg.template.json
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Original file line number Diff line number Diff line change
Expand Up @@ -27,6 +27,17 @@
}
},
"Resource": "*"
},
{
"Action": [
"kms:Decrypt",
"kms:GenerateDataKey*"
],
"Effect": "Allow",
"Principal": {
"Service": "s3.amazonaws.com"
},
"Resource": "*"
}
],
"Version": "2012-10-17"
Expand Down Expand Up @@ -132,12 +143,6 @@
"Type": "AWS::SNS::Topic",
"Properties": {
"DisplayName": "fooDisplayName2",
"KmsMasterKeyId": {
"Fn::GetAtt": [
"CustomKey1E6D0D07",
"Arn"
]
},
"TopicName": "fooTopic2"
}
},
Expand Down Expand Up @@ -166,8 +171,26 @@
{
"Action": "sns:Publish",
"Effect": "Allow",
"Resource": [
{
"Ref": "MyTopic288CE2107"
},
{
"Ref": "MyTopic3134CFDFB"
}
]
},
{
"Action": [
"kms:Decrypt",
"kms:GenerateDataKey*"
],
"Effect": "Allow",
"Resource": {
"Ref": "MyTopic288CE2107"
"Fn::GetAtt": [
"CustomKey1E6D0D07",
"Arn"
]
}
}
],
Expand All @@ -180,6 +203,19 @@
}
]
}
},
"MyTopic3134CFDFB": {
"Type": "AWS::SNS::Topic",
"Properties": {
"DisplayName": "fooDisplayName3",
"KmsMasterKeyId": {
"Fn::GetAtt": [
"CustomKey1E6D0D07",
"Arn"
]
},
"TopicName": "fooTopic3"
}
}
},
"Parameters": {
Expand Down
2 changes: 1 addition & 1 deletion packages/@aws-cdk-testing/framework-integ/test/aws-sns/test/integ.sns.js.snapshot/cdk.out
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2 changes: 1 addition & 1 deletion packages/@aws-cdk-testing/framework-integ/test/aws-sns/test/integ.sns.js.snapshot/integ.json
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10 changes: 8 additions & 2 deletions ...es/@aws-cdk-testing/framework-integ/test/aws-sns/test/integ.sns.js.snapshot/manifest.json
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96 changes: 85 additions & 11 deletions packages/@aws-cdk-testing/framework-integ/test/aws-sns/test/integ.sns.js.snapshot/tree.json
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24 changes: 21 additions & 3 deletions packages/@aws-cdk-testing/framework-integ/test/aws-sns/test/integ.sns.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -62,14 +62,32 @@ class SNSInteg extends Stack {
const topic2 = new Topic(this, 'MyTopic2', {
topicName: 'fooTopic2',
displayName: 'fooDisplayName2',
masterKey: key,
});
const importedTopic = Topic.fromTopicArn(this, 'ImportedTopic', topic2.topicArn);
const importedTopic2 = Topic.fromTopicArn(this, 'ImportedTopic2', topic2.topicArn);

const publishRole = new Role(this, 'PublishRole', {
assumedBy: new ServicePrincipal('s3.amazonaws.com'),
});
importedTopic.grantPublish(publishRole);
importedTopic2.grantPublish(publishRole);

// Can import encrypted topic by attributes
const topic3 = new Topic(this, 'MyTopic3', {
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Couldn't we import topic2 instead?

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Sorry, not sure I understand the suggestion, do you mean topic? I can try to provide some of my thinking here:

  • The existing test is showing a non-functional example. importedTopic isn't aware there's a KMS key so grantPublish doesn't work.
  • I unencrypted topic2, so that importing with fromTopicArn and calling grantPublish does work.
  • That left me wanting to import an encrypted topic, so I created topic3 and used fromTopicAttributes, testing the same basic flow.

topic is encrypted and could be used for importing... it's just created up higher, and it felt like we'd moved on from it flow-wise.

I'm not totally sure what the norm is here, so your guidance is appreciated!

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Thanks for clarifying 👍 Your implementation makes sense as is

topicName: 'fooTopic3',
displayName: 'fooDisplayName3',
masterKey: key,
});
const importedTopic3 = Topic.fromTopicAttributes(this, 'ImportedTopic3', {
topicArn: topic3.topicArn,
keyArn: key.keyArn,
});
importedTopic3.grantPublish(publishRole);

// Can reference KMS key after creation
topic3.masterKey!.addToResourcePolicy(new PolicyStatement({
principals: [new ServicePrincipal('s3.amazonaws.com')],
actions: ['kms:GenerateDataKey*', 'kms:Decrypt'],
resources: ['*'],
}));
}
}

Expand Down
20 changes: 19 additions & 1 deletion packages/aws-cdk-lib/aws-sns/lib/topic-base.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@ import { ITopicSubscription } from './subscriber';
import { Subscription } from './subscription';
import * as notifications from '../../aws-codestarnotifications';
import * as iam from '../../aws-iam';
import { IKey } from '../../aws-kms';
import { IResource, Resource, ResourceProps, Token } from '../../core';

/**
Expand All @@ -25,6 +26,17 @@ export interface ITopic extends IResource, notifications.INotificationRuleTarget
*/
readonly topicName: string;

/**
* A KMS Key, either managed by this CDK app, or imported.
*
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Suggested change
*
*
* This property applies only to server-side encryption.
*
* @see https://docs.aws.amazon.com/sns/latest/dg/sns-server-side-encryption.html

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Added, thanks!

* This property applies only to server-side encryption.
*
* @see https://docs.aws.amazon.com/sns/latest/dg/sns-server-side-encryption.html
*
* @default None
*/
readonly masterKey?: IKey;

/**
* Enables content-based deduplication for FIFO topics.
*
Expand Down Expand Up @@ -72,6 +84,8 @@ export abstract class TopicBase extends Resource implements ITopic {

public abstract readonly topicName: string;

public abstract readonly masterKey?: IKey;

public abstract readonly fifo: boolean;

public abstract readonly contentBasedDeduplication: boolean;
Expand Down Expand Up @@ -173,12 +187,16 @@ export abstract class TopicBase extends Resource implements ITopic {
* Grant topic publishing permissions to the given identity
*/
public grantPublish(grantee: iam.IGrantable) {
return iam.Grant.addToPrincipalOrResource({
const ret = iam.Grant.addToPrincipalOrResource({
grantee,
actions: ['sns:Publish'],
resourceArns: [this.topicArn],
resource: this,
});
if (this.masterKey) {
this.masterKey.grant(grantee, 'kms:Decrypt', 'kms:GenerateDataKey*');
}
return ret;
}

/**
Expand Down
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