[Hardening] F-12: Absence of Per-Account or Per-User Source CIDR Allowlist.

### The required feature described as a wish

**Description:** CloudStack does not provide a built-in mechanism to restrict per-account or per-user access to a defined set of source IP addresses or CIDR ranges. Any IP address that can reach the management plane can attempt to authenticate as any account.

**Affected Components:** Management UI / API

**Impact:** Without source IP allowlisting, a stolen API key or compromised credential set can be used from any network location globally. There is no network-level control to limit the blast radius of a credential compromise. High-privilege service accounts are particularly at risk, as they can be accessed from unexpected locations without raising any flags.

**Steps to Reproduce:**
- This finding is not directly reproducible since it reflects the absence of a control.

**Recommended Remediation:** Implement a per-account or per-user source CIDR allowlist field in the data model. Requests originating from IPs outside the defined allowlist should be rejected and logged as a security event.

该 issue 指出了 Management UI/API、account 或 user 数据模型、请求源 IP 检查以及 Security-Event 日志记录，但没有列出文件或测试。首先定位这些入口点，并跟踪 API 请求的 authentication 和 authorization。完成时应包括按 account 或 user 定义的 CIDR 策略、对策略范围之外请求的拒绝，以及记录 Security-Events，并覆盖相关行为。

由索引模型根据 Issue 内容生成。