s3-bucket-policy

To create an S3 bucket policy for cross-account access, you define an IAM policy that explicitly grants permissions to a target AWS account ID. This securely allows external accounts to access your specified S3 bucket resources.

An S3 bucket policy throws an AccessDenied error when IAM permissions conflict with bucket restrictions or lack explicit resource access. Analyzing the policy statements helps identify and resolve conflicting permission blocks.

The best way to enforce encryption using S3 bucket policies is to implement a deny statement that rejects requests missing secure transport headers. This security best practice ensures all stored data remains encrypted.

To restrict S3 bucket access to specific IP ranges, you configure a bucket policy with an explicit deny statement conditioned on the aws:SourceIp element. This blocks all traffic outside your approved network ranges.

When hitting S3 bucket policy size limits, you must optimize your existing IAM policies by consolidating redundant statements and using wildcard resources. This reduces the overall policy footprint while maintaining access control.

Yes, you can securely grant read-only S3 bucket access to a partner account by creating a policy that restricts actions to s3:GetObject. This ensures the partner can retrieve data without modifying your bucket.