2564 Policies 97396345

# IAM Policy Patterns

Detailed patterns and examples for IAM policies.

## Policy Structure

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "DescriptiveStatementId",
      "Effect": "Allow",
      "Action": ["service:Action"],
      "Resource": ["arn:aws:service:region:account:resource"],
      "Condition": {
        "ConditionOperator": {
          "ConditionKey": "value"
        }
      }
    }
  ]
}
```

## Common Policy Patterns

### S3 Bucket Access

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "ListBucket",
      "Effect": "Allow",
      "Action": "s3:ListBucket",
      "Resource": "arn:aws:s3:::my-bucket",
      "Condition": {
        "StringLike": {
          "s3:prefix": ["${aws:username}/*"]
        }
      }
    },
    {
      "Sid": "ReadWriteObjects",
      "Effect": "Allow",
      "Action": ["s3:GetObject", "s3:PutObject", "s3:DeleteObject"],
      "Resource": "arn:aws:s3:::my-bucket/${aws:username}/*"
    }
  ]
}
```

### DynamoDB Table Access

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "dynamodb:GetItem",
        "dynamodb:PutItem",
        "dynamodb:UpdateItem",
        "dynamodb:DeleteItem",
        "dynamodb:Query"
      ],
      "Resource": [
        "arn:aws:dynamodb:us-east-1:123456789012:table/MyTable",
        "arn:aws:dynamodb:us-east-1:123456789012:table/MyTable/index/*"
      ]
    }
  ]
}
```

### Lambda Execution with Logging

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "logs:CreateLogGroup",
        "logs:CreateLogStream",
        "logs:PutLogEvents"
      ],
      "Resource": "arn:aws:logs:*:*:log-group:/aws/lambda/*"
    }
  ]
}
```

### Secrets Manager Access

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "secretsmanager:GetSecretValue",
        "secretsmanager:DescribeSecret"
      ],
      "Resource": "arn:aws:secretsmanager:us-east-1:123456789012:secret:prod/*",
      "Condition": {
        "StringEquals": {
          "secretsmanager:ResourceTag/Environment": "production"
        }
      }
    }
  ]
}
```

### EC2 Instance Management with Tags

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "ec2:StartInstances",
        "ec2:StopInstances",
        "ec2:RebootInstances"
      ],
      "Resource": "arn:aws:ec2:*:*:instance/*",
      "Condition": {
        "StringEquals": {
          "aws:ResourceTag/Team": "${aws:PrincipalTag/Team}"
        }
      }
    },
    {
      "Effect": "Allow",
      "Action": "ec2:DescribeInstances",
      "Resource": "*"
    }
  ]
}
```

## Condition Keys

### Common Global Condition Keys

| Key | Description | Example |
|-----|-------------|---------|
| `aws:SourceIp` | Request IP address | Restrict to office IPs |
| `aws:CurrentTime` | Current date/time | Allow only during business hours |
| `aws:MultiFactorAuthPresent` | MFA used | Require MFA for sensitive actions |
| `aws:PrincipalTag/key` | Tag on the principal | ABAC patterns |
| `aws:ResourceTag/key` | Tag on the resource | ABAC patterns |
| `aws:RequestedRegion` | Target region | Restrict to specific regions |

### MFA Enforcement

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Deny",
      "Action": "*",
      "Resource": "*",
      "Condition": {
        "BoolIfExists": {
          "aws:MultiFactorAuthPresent": "false"
        }
      }
    }
  ]
}
```

### IP Restriction

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Deny",
      "Action": "*",
      "Resource": "*",
      "Condition": {
        "NotIpAddress": {
          "aws:SourceIp": ["192.0.2.0/24", "203.0.113.0/24"]
        }
      }
    }
  ]
}
```

### Region Restriction

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Deny",
      "Action": "*",
      "Resource": "*",
      "Condition": {
        "StringNotEquals": {
          "aws:RequestedRegion": ["us-east-1", "us-west-2"]
        }
      }
    }
  ]
}
```

## Trust Policy Patterns

### Lambda Service Trust

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "lambda.amazonaws.com"
      },
      "Action": "sts:AssumeRole"
    }
  ]
}
```

### Cross-Account with External ID

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::111111111111:root"
      },
      "Action": "sts:AssumeRole",
      "Condition": {
        "StringEquals": {
          "sts:ExternalId": "unique-secret-id"
        }
      }
    }
  ]
}
```

### Federated Identity (OIDC)

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Federated": "arn:aws:iam::123456789012:oidc-provider/token.actions.githubusercontent.com"
      },
      "Action": "sts:AssumeRoleWithWebIdentity",
      "Condition": {
        "StringEquals": {
          "token.actions.githubusercontent.com:aud": "sts.amazonaws.com"
        },
        "StringLike": {
          "token.actions.githubusercontent.com:sub": "repo:my-org/my-repo:*"
        }
      }
    }
  ]
}
```

## Resource-Based Policy Patterns

### S3 Bucket Policy

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Sid": "AllowCrossAccountAccess",
      "Effect": "Allow",
      "Principal": {
        "AWS": "arn:aws:iam::111111111111:role/CrossAccountRole"
      },
      "Action": ["s3:GetObject", "s3:ListBucket"],
      "Resource": [
        "arn:aws:s3:::my-bucket",
        "arn:aws:s3:::my-bucket/*"
      ]
    }
  ]
}
```

### SQS Queue Policy

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Principal": {
        "Service": "sns.amazonaws.com"
      },
      "Action": "sqs:SendMessage",
      "Resource": "arn:aws:sqs:us-east-1:123456789012:my-queue",
      "Condition": {
        "ArnEquals": {
          "aws:SourceArn": "arn:aws:sns:us-east-1:123456789012:my-topic"
        }
      }
    }
  ]
}
```

## Permission Boundaries

Permission boundaries limit the maximum permissions a role can have:

```json
{
  "Version": "2012-10-17",
  "Statement": [
    {
      "Effect": "Allow",
      "Action": [
        "s3:*",
        "dynamodb:*",
        "lambda:*",
        "logs:*"
      ],
      "Resource": "*"
    },
    {
      "Effect": "Deny",
      "Action": [
        "iam:*",
        "organizations:*",
        "account:*"
      ],
      "Resource": "*"
    }
  ]
}
```

Apply to a role:

```bash
aws iam put-role-permissions-boundary \
  --role-name DeveloperRole \
  --permissions-boundary arn:aws:iam::123456789012:policy/DeveloperBoundary
```