kms: All principals in a PolicyStatement must have the same Conditions for cross-account policy

[pahud]

Describe the bug

CDK synth is having Resolution error: All principals in a PolicyStatement must have the same Conditions by adding a cross-account plicy.

Expected Behavior

synthesize with no error

Current Behavior

Error: Resolution error: Resolution error: Resolution error: All principals in a PolicyStatement must have the same Conditions (got '{"StringEquals":{"kms:ViaService":"secretsmanager.us-east-1.amazonaws.com"}}' and '{}'). Use multiple statements instead..
Object creation stack:
  at stack traces disabled..
    at PolicyStatement.addPrincipalConditions (/projects/issue-triage/node_modules/aws-cdk-lib/aws-iam/lib/policy-statement.js:2:7201)
    at PolicyStatement.addPrincipals (/projects/issue-triage/node_modules/aws-cdk-lib/aws-iam/lib/policy-statement.js:2:2407)
    at new PolicyStatement (/projects/issue-triage/node_modules/aws-cdk-lib/aws-iam/lib/policy-statement.js:2:663)
    at PolicyStatement.copy (/projects/issue-triage/node_modules/aws-cdk-lib/aws-iam/lib/policy-statement.js:2:6086)
    at mergeIfCombinable (/projects/issue-triage/node_modules/aws-cdk-lib/aws-iam/lib/private/merge-statements.js:1:1847)
    at onePass (/projects/issue-triage/node_modules/aws-cdk-lib/aws-iam/lib/private/merge-statements.js:1:1032)
    at mergeStatements (/projects/issue-triage/node_modules/aws-cdk-lib/aws-iam/lib/private/merge-statements.js:1:660)
    at PolicyDocument._maybeMergeStatements (/projects/issue-triage/node_modules/aws-cdk-lib/aws-iam/lib/policy-document.js:1:3033)
    at PolicyDocument.resolve (/projects/issue-triage/node_modules/aws-cdk-lib/aws-iam/lib/policy-document.js:1:1755)
    at RememberingTokenResolver.resolveToken (/projects/issue-triage/node_modules/aws-cdk-lib/core/lib/resolvable.js:1:1401)

Reproduction Steps

export class DummyStack extends Stack {
  constructor(scope: Construct, id: string, props: StackProps) {
    super(scope, id, props);

    const dummyKey = new kms.Key(this, 'Key', {
      alias: 'keyalias',
      enableKeyRotation: true,
      keyUsage: KeyUsage.ENCRYPT_DECRYPT,
      keySpec: KeySpec.SYMMETRIC_DEFAULT,
    });


    new secrets.Secret(this, 'Secret', {
      encryptionKey: dummyKey,
    });

    const crossAccountAccessPolicy = new iam.PolicyStatement({
      actions: [
        'kms:CreateGrant',
        'kms:Decrypt',
        'kms:DescribeKey',
        'kms:Encrypt',
        'kms:GenerateDataKey*',
        'kms:ReEncrypt*'
      ],
      principals: [
        new iam.AccountPrincipal('123456789012'),
      ],
      resources: ['*'],
      conditions: {
        'StringEquals': { 'kms:ViaService': 'secretsmanager.us-east-1.amazonaws.com'}
      }
    })

    dummyKey.addToResourcePolicy(crossAccountAccessPolicy);

  }
}
     

Possible Solution

No response

Additional Information/Context

No response

CDK CLI Version

2.126.0 (build fb74c41)

Framework Version

No response

Node.js Version

v20.6.1

OS

linux

Language

TypeScript

Language Version

No response

Other information

No response

[pahud]

internal tracking: V1241367978

[xazhao]

Can't reproduce this issue. Looking at the internal tracking ticket, this happens when encryptionKey: dummyKey creates the policy with same action/condition as crossAccountAccessPolicy which will cause conflicts.
When I run the synth, condition created by encryptionKey: dummyKey is

Condition:
  StringEquals:
    kms:ViaService:
      Fn::Join:
        - ""
        - - secretsmanager.
          - Ref: AWS::Region
          - .amazonaws.com

while the condition in crossAccountAccessPolicy is

{
  'StringEquals': { 'kms:ViaService': 'secretsmanager.us-east-1.amazonaws.com'}
}

The region is not resolved in the output template hence not causing conflicts. I'm going to close the issue for now. If this issue still exists, feel free to re-open it.

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