54a4e59af9
根因：host_resource_alert 規則使用 {host}（由 instance label 派生），
與 {target} 無關；但 host 告警缺少 K8s deployment label 導致 target=unknown，
_is_bad_target=True → kubectl_command 被清空 → auto_approve 以
no_executable_action 拒絕 → 每日 3 次人工攔截。
修復：
- alert_rule_engine.py: SSH 指令（startswith "ssh "）跳過 bad_target 驗證
- prompts.py: 主 + Nemo prompt 補 Host* 告警 SSH 診斷規則，防 LLM fallback 路徑輸出 kubectl
- ssh_command_whitelist.py: 新建唯讀 SSH 指令白名單模組（供 _ssh_execute() 執行前驗證）
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
122 lines
2.7 KiB
Python
122 lines
2.7 KiB
Python
"""
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SSH 唯讀診斷指令白名單 — 防止 RCE
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2026-05-04 ogt + Claude Sonnet 4.6:
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設計原則：
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- 只允許純唯讀指令（top/uptime/free/df/ps/cat /proc/*）
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- 禁止任何 shell metachar（compound/pipeline/substitution/redirect）
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- 由 validate_kubectl_command() 的 "ssh " 豁免確保進規則路徑；
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本模組為補充安全層，供未來 _ssh_execute() 執行前再次驗證。
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"""
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# 允許的指令前綴（唯讀診斷用）
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_SAFE_PREFIXES: tuple[str, ...] = (
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"top -bn1",
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"uptime",
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"free -m",
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"free -h",
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"df -h",
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"df -hT",
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"iostat",
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"vmstat",
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"ps aux",
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"ps -ef",
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"cat /proc/loadavg",
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"cat /proc/meminfo",
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"cat /proc/cpuinfo",
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"echo ",
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)
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# 禁止的 shell metachar — 防止指令注入
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_DANGEROUS_PATTERNS: tuple[str, ...] = (
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";",
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"&&",
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"||",
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"|",
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">",
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"<",
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"`",
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"$(",
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"${",
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"\\n",
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"\n",
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"rm ",
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"kill ",
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"pkill ",
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"reboot",
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"shutdown",
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"poweroff",
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"dd ",
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"mkfs",
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"fdisk",
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"wget ",
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"curl ",
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"nc ",
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"ncat ",
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"bash ",
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"sh ",
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"python",
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"perl",
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"ruby",
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"exec ",
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)
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def is_safe_ssh_command(cmd: str) -> bool:
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"""
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驗證 SSH 指令是否為唯讀安全指令。
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規則：
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1. 必須以 _SAFE_PREFIXES 其中一個前綴開頭
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2. 不得含有任何 _DANGEROUS_PATTERNS
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Args:
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cmd: 要驗證的 SSH 指令字串（不含前導 "ssh <host> '" 包裝）
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Returns:
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True — 安全，可執行
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False — 含危險模式，應拒絕
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"""
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if not cmd or not cmd.strip():
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return False
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cmd_stripped = cmd.strip()
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# 先阻擋危險模式（優先於前綴白名單）
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for pattern in _DANGEROUS_PATTERNS:
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if pattern in cmd_stripped:
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return False
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# 必須以白名單前綴開頭
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return any(cmd_stripped.startswith(prefix) for prefix in _SAFE_PREFIXES)
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def extract_inner_command(ssh_cmd: str) -> str:
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"""
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從完整 SSH 指令中提取內層指令供 is_safe_ssh_command() 驗證。
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範例：
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"ssh 192.168.1.1 'uptime'" → "uptime"
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"ssh -o StrictHostKeyChecking=no host 'free -m'" → "free -m"
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Args:
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ssh_cmd: 完整 SSH 指令字串
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Returns:
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內層指令字串；若解析失敗返回原始字串
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"""
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if not ssh_cmd.startswith("ssh "):
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return ssh_cmd
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# 找最後一對單引號或雙引號包裝的指令
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for quote in ("'", '"'):
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last_open = ssh_cmd.rfind(quote)
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if last_open == -1:
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continue
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first_open = ssh_cmd.find(quote)
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if first_open == last_open:
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continue
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return ssh_cmd[first_open + 1 : last_open]
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return ssh_cmd
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