Xubin Ren 5dc238c7ef fix(shell): allow read-only copies from internal state files
Keep the new exec guard focused on writes to history.jsonl and .dream_cursor while still allowing read-only copy operations out of those files.

Made-with: Cursor
2026-04-12 16:38:55 +08:00

319 lines
12 KiB
Python

"""Shell execution tool."""
import asyncio
import os
import re
import shutil
import sys
from pathlib import Path
from typing import Any
from loguru import logger
from nanobot.agent.tools.base import Tool, tool_parameters
from nanobot.agent.tools.sandbox import wrap_command
from nanobot.agent.tools.schema import IntegerSchema, StringSchema, tool_parameters_schema
from nanobot.config.paths import get_media_dir
_IS_WINDOWS = sys.platform == "win32"
@tool_parameters(
tool_parameters_schema(
command=StringSchema("The shell command to execute"),
working_dir=StringSchema("Optional working directory for the command"),
timeout=IntegerSchema(
60,
description=(
"Timeout in seconds. Increase for long-running commands "
"like compilation or installation (default 60, max 600)."
),
minimum=1,
maximum=600,
),
required=["command"],
)
)
class ExecTool(Tool):
"""Tool to execute shell commands."""
def __init__(
self,
timeout: int = 60,
working_dir: str | None = None,
deny_patterns: list[str] | None = None,
allow_patterns: list[str] | None = None,
restrict_to_workspace: bool = False,
sandbox: str = "",
path_append: str = "",
allowed_env_keys: list[str] | None = None,
):
self.timeout = timeout
self.working_dir = working_dir
self.sandbox = sandbox
self.deny_patterns = deny_patterns or [
r"\brm\s+-[rf]{1,2}\b", # rm -r, rm -rf, rm -fr
r"\bdel\s+/[fq]\b", # del /f, del /q
r"\brmdir\s+/s\b", # rmdir /s
r"(?:^|[;&|]\s*)format\b", # format (as standalone command only)
r"\b(mkfs|diskpart)\b", # disk operations
r"\bdd\s+if=", # dd
r">\s*/dev/sd", # write to disk
r"\b(shutdown|reboot|poweroff)\b", # system power
r":\(\)\s*\{.*\};\s*:", # fork bomb
# Block writes to nanobot internal state files (#2989).
# history.jsonl / .dream_cursor are managed by append_history();
# direct writes corrupt the cursor format and crash /dream.
r">>?\s*\S*(?:history\.jsonl|\.dream_cursor)", # > / >> redirect
r"\btee\b[^|;&<>]*(?:history\.jsonl|\.dream_cursor)", # tee / tee -a
r"\b(?:cp|mv)\b(?:\s+[^\s|;&<>]+)+\s+\S*(?:history\.jsonl|\.dream_cursor)", # cp/mv target
r"\bdd\b[^|;&<>]*\bof=\S*(?:history\.jsonl|\.dream_cursor)", # dd of=
r"\bsed\s+-i[^|;&<>]*(?:history\.jsonl|\.dream_cursor)", # sed -i
]
self.allow_patterns = allow_patterns or []
self.restrict_to_workspace = restrict_to_workspace
self.path_append = path_append
self.allowed_env_keys = allowed_env_keys or []
@property
def name(self) -> str:
return "exec"
_MAX_TIMEOUT = 600
_MAX_OUTPUT = 10_000
@property
def description(self) -> str:
return (
"Execute a shell command and return its output. "
"Prefer read_file/write_file/edit_file over cat/echo/sed, "
"and grep/glob over shell find/grep. "
"Use -y or --yes flags to avoid interactive prompts. "
"Output is truncated at 10 000 chars; timeout defaults to 60s."
)
@property
def exclusive(self) -> bool:
return True
async def execute(
self, command: str, working_dir: str | None = None,
timeout: int | None = None, **kwargs: Any,
) -> str:
cwd = working_dir or self.working_dir or os.getcwd()
# Prevent an LLM-supplied working_dir from escaping the configured
# workspace when restrict_to_workspace is enabled (#2826). Without
# this, a caller can pass working_dir="/etc" and then all absolute
# paths under /etc would pass the _guard_command check that anchors
# on cwd.
if self.restrict_to_workspace and self.working_dir:
try:
requested = Path(cwd).expanduser().resolve()
workspace_root = Path(self.working_dir).expanduser().resolve()
except Exception:
return "Error: working_dir could not be resolved"
if requested != workspace_root and workspace_root not in requested.parents:
return "Error: working_dir is outside the configured workspace"
guard_error = self._guard_command(command, cwd)
if guard_error:
return guard_error
if self.sandbox:
if _IS_WINDOWS:
logger.warning(
"Sandbox '{}' is not supported on Windows; running unsandboxed",
self.sandbox,
)
else:
workspace = self.working_dir or cwd
command = wrap_command(self.sandbox, command, workspace, cwd)
cwd = str(Path(workspace).resolve())
effective_timeout = min(timeout or self.timeout, self._MAX_TIMEOUT)
env = self._build_env()
if self.path_append:
if _IS_WINDOWS:
env["PATH"] = env.get("PATH", "") + ";" + self.path_append
else:
command = f'export PATH="$PATH:{self.path_append}"; {command}'
try:
process = await self._spawn(command, cwd, env)
try:
stdout, stderr = await asyncio.wait_for(
process.communicate(),
timeout=effective_timeout,
)
except asyncio.TimeoutError:
await self._kill_process(process)
return f"Error: Command timed out after {effective_timeout} seconds"
except asyncio.CancelledError:
await self._kill_process(process)
raise
output_parts = []
if stdout:
output_parts.append(stdout.decode("utf-8", errors="replace"))
if stderr:
stderr_text = stderr.decode("utf-8", errors="replace")
if stderr_text.strip():
output_parts.append(f"STDERR:\n{stderr_text}")
output_parts.append(f"\nExit code: {process.returncode}")
result = "\n".join(output_parts) if output_parts else "(no output)"
max_len = self._MAX_OUTPUT
if len(result) > max_len:
half = max_len // 2
result = (
result[:half]
+ f"\n\n... ({len(result) - max_len:,} chars truncated) ...\n\n"
+ result[-half:]
)
return result
except Exception as e:
return f"Error executing command: {str(e)}"
@staticmethod
async def _spawn(
command: str, cwd: str, env: dict[str, str],
) -> asyncio.subprocess.Process:
"""Launch *command* in a platform-appropriate shell."""
if _IS_WINDOWS:
comspec = env.get("COMSPEC", os.environ.get("COMSPEC", "cmd.exe"))
return await asyncio.create_subprocess_exec(
comspec, "/c", command,
stdout=asyncio.subprocess.PIPE,
stderr=asyncio.subprocess.PIPE,
cwd=cwd,
env=env,
)
bash = shutil.which("bash") or "/bin/bash"
return await asyncio.create_subprocess_exec(
bash, "-l", "-c", command,
stdout=asyncio.subprocess.PIPE,
stderr=asyncio.subprocess.PIPE,
cwd=cwd,
env=env,
)
@staticmethod
async def _kill_process(process: asyncio.subprocess.Process) -> None:
"""Kill a subprocess and reap it to prevent zombies."""
process.kill()
try:
await asyncio.wait_for(process.wait(), timeout=5.0)
except asyncio.TimeoutError:
pass
finally:
if not _IS_WINDOWS:
try:
os.waitpid(process.pid, os.WNOHANG)
except (ProcessLookupError, ChildProcessError) as e:
logger.debug("Process already reaped or not found: {}", e)
def _build_env(self) -> dict[str, str]:
"""Build a minimal environment for subprocess execution.
On Unix, only HOME/LANG/TERM are passed; ``bash -l`` sources the
user's profile which sets PATH and other essentials.
On Windows, ``cmd.exe`` has no login-profile mechanism, so a curated
set of system variables (including PATH) is forwarded. API keys and
other secrets are still excluded.
"""
if _IS_WINDOWS:
sr = os.environ.get("SYSTEMROOT", r"C:\Windows")
env = {
"SYSTEMROOT": sr,
"COMSPEC": os.environ.get("COMSPEC", f"{sr}\\system32\\cmd.exe"),
"USERPROFILE": os.environ.get("USERPROFILE", ""),
"HOMEDRIVE": os.environ.get("HOMEDRIVE", "C:"),
"HOMEPATH": os.environ.get("HOMEPATH", "\\"),
"TEMP": os.environ.get("TEMP", f"{sr}\\Temp"),
"TMP": os.environ.get("TMP", f"{sr}\\Temp"),
"PATHEXT": os.environ.get("PATHEXT", ".COM;.EXE;.BAT;.CMD"),
"PATH": os.environ.get("PATH", f"{sr}\\system32;{sr}"),
"APPDATA": os.environ.get("APPDATA", ""),
"LOCALAPPDATA": os.environ.get("LOCALAPPDATA", ""),
"ProgramData": os.environ.get("ProgramData", ""),
"ProgramFiles": os.environ.get("ProgramFiles", ""),
"ProgramFiles(x86)": os.environ.get("ProgramFiles(x86)", ""),
"ProgramW6432": os.environ.get("ProgramW6432", ""),
}
for key in self.allowed_env_keys:
val = os.environ.get(key)
if val is not None:
env[key] = val
return env
home = os.environ.get("HOME", "/tmp")
env = {
"HOME": home,
"LANG": os.environ.get("LANG", "C.UTF-8"),
"TERM": os.environ.get("TERM", "dumb"),
}
for key in self.allowed_env_keys:
val = os.environ.get(key)
if val is not None:
env[key] = val
return env
def _guard_command(self, command: str, cwd: str) -> str | None:
"""Best-effort safety guard for potentially destructive commands."""
cmd = command.strip()
lower = cmd.lower()
for pattern in self.deny_patterns:
if re.search(pattern, lower):
return "Error: Command blocked by safety guard (dangerous pattern detected)"
if self.allow_patterns:
if not any(re.search(p, lower) for p in self.allow_patterns):
return "Error: Command blocked by safety guard (not in allowlist)"
from nanobot.security.network import contains_internal_url
if contains_internal_url(cmd):
return "Error: Command blocked by safety guard (internal/private URL detected)"
if self.restrict_to_workspace:
if "..\\" in cmd or "../" in cmd:
return "Error: Command blocked by safety guard (path traversal detected)"
cwd_path = Path(cwd).resolve()
for raw in self._extract_absolute_paths(cmd):
try:
expanded = os.path.expandvars(raw.strip())
p = Path(expanded).expanduser().resolve()
except Exception:
continue
media_path = get_media_dir().resolve()
if (p.is_absolute()
and cwd_path not in p.parents
and p != cwd_path
and media_path not in p.parents
and p != media_path
):
return "Error: Command blocked by safety guard (path outside working dir)"
return None
@staticmethod
def _extract_absolute_paths(command: str) -> list[str]:
# Windows: match drive-root paths like `C:\` as well as `C:\path\to\file`
# NOTE: `*` is required so `C:\` (nothing after the slash) is still extracted.
win_paths = re.findall(r"[A-Za-z]:\\[^\s\"'|><;]*", command)
posix_paths = re.findall(r"(?:^|[\s|>'\"])(/[^\s\"'>;|<]+)", command) # POSIX: /absolute only
home_paths = re.findall(r"(?:^|[\s|>'\"])(~[^\s\"'>;|<]*)", command) # POSIX/Windows home shortcut: ~
return win_paths + posix_paths + home_paths