fix(security): reject inode aliases and workspace redirects

src/agent_tools/filesystem_tools.py

@@ -646,10 +646,13 @@ class GrepTool:
                     remaining_hits = max_hits - len(lines)
                     if remaining_hits <= 0:
                         break
+                    # JSON output gives us the canonical match pathname so it
+                    # can be revalidated before any line reaches the model.
+                    # This is required for hardlink aliases inside an allowed
+                    # workspace; lexical/path checks alone cannot see them.
                     cmd = [
-                        rg, "--no-config", "--no-follow", "--line-number",
-                        "--no-heading", "--color=never", "--max-count",
-                        str(remaining_hits),
+                        rg, "--json", "--no-config", "--no-follow",
+                        "--max-count", str(remaining_hits),
                     ]
                     if ignore_case:
                         cmd.append("--ignore-case")
@@ -703,8 +706,38 @@ class GrepTool:
                                 return None, "grep: timed out"
                             if line is None:
                                 break
-                            if line and line not in lines:
+                            if not line:
+                                continue
+                            try:
+                                event = json.loads(line)
+                            except (TypeError, json.JSONDecodeError):
+                                # Keep lightweight/fake runners compatible with
+                                # the historical plain `path:line:text` stream;
+                                # still revalidate the path before exposing it.
+                                pieces = line.split(":", 2)
+                                if len(pieces) >= 3:
+                                    plain_path = pieces[0]
+                                    if not _is_denied_tool_path(os.path.realpath(plain_path)):
+                                        if line not in lines:
                                             lines.append(line)
+                                continue
+                            if event.get("type") != "match":
+                                continue
+                            match = event.get("data") or {}
+                            path_data = match.get("path") or {}
+                            match_path = path_data.get("text")
+                            if not match_path:
+                                continue
+                            if _is_denied_tool_path(os.path.realpath(match_path)):
+                                continue
+                            line_text = (match.get("lines") or {}).get("text", "")
+                            line_number = match.get("line_number", "?")
+                            rendered = (
+                                f"{match_path}:{line_number}:"
+                                f"{line_text.rstrip()[:_CODENAV_MAX_LINE]}"
+                            )
+                            if rendered not in lines:
+                                lines.append(rendered)
                     finally:
                         if process.poll() is None:
                             process.terminate()

src/app_initializer.py

@@ -2,6 +2,7 @@
 """Initialize all application components and dependencies."""
 import os
 import logging
+import stat
 from typing import Dict, Any
 
 from src.constants import (
@@ -28,10 +29,37 @@ logger = logging.getLogger(__name__)
 
 def create_directories():
     """Create necessary directories if they don't exist."""
-    for directory in (DATA_DIR, PERSONAL_DIR, RUNBOOK_DIR, UPLOAD_DIR,
-                      AGENT_WORKSPACE_DIR):
+    for directory in (DATA_DIR, PERSONAL_DIR, RUNBOOK_DIR, UPLOAD_DIR):
         os.makedirs(directory, exist_ok=True)
 
+    # The model-controlled workspace must be a real child of DATA_DIR.  Never
+    # follow a pre-existing symlink here: it would silently move the default
+    # native-file root outside the application volume before any resolver runs.
+    data_root = os.path.realpath(DATA_DIR)
+    workspace = os.path.abspath(os.path.expanduser(AGENT_WORKSPACE_DIR))
+    try:
+        if os.path.commonpath([workspace, data_root]) != data_root or workspace == data_root:
+            raise RuntimeError("agent workspace must resolve inside DATA_DIR")
+    except ValueError as exc:
+        raise RuntimeError("agent workspace must resolve inside DATA_DIR") from exc
+    if os.path.lexists(workspace):
+        mode = os.lstat(workspace).st_mode
+        if stat.S_ISLNK(mode) or not stat.S_ISDIR(mode):
+            raise RuntimeError("agent workspace must be a real directory")
+    else:
+        os.mkdir(workspace, 0o700)
+    resolved_workspace = os.path.realpath(workspace)
+    try:
+        inside = os.path.commonpath([resolved_workspace, data_root]) == data_root
+    except ValueError:
+        inside = False
+    if resolved_workspace == data_root or not inside:
+        raise RuntimeError("agent workspace must resolve inside DATA_DIR")
+    try:
+        os.chmod(workspace, 0o700)
+    except OSError:
+        pass
+
 def initialize_managers(base_dir: str, rag_manager=None) -> Dict[str, Any]:
     """
     Initialize all manager and handler instances.

src/tool_execution.py

@@ -15,6 +15,7 @@ import logging
 import os
 import pathlib
 import re
+import stat
 import sys
 import time
 from typing import Any, Awaitable, Callable, Dict, Optional, Tuple
@@ -259,9 +260,22 @@ def _is_app_state_path(resolved: str) -> bool:
     )
 
 
+def _is_hardlinked_regular_file(resolved: str) -> bool:
+    """Reject inode aliases that can smuggle DATA_DIR state into an allow root."""
+    try:
+        target = os.stat(resolved, follow_symlinks=False)
+    except OSError:
+        return False
+    return stat.S_ISREG(target.st_mode) and getattr(target, "st_nlink", 1) > 1
+
+
 def _is_denied_tool_path(resolved: str) -> bool:
     """Apply every path deny to a canonical traversal result."""
-    return _is_sensitive_path(resolved) or _is_app_state_path(resolved)
+    return (
+        _is_sensitive_path(resolved)
+        or _is_app_state_path(resolved)
+        or _is_hardlinked_regular_file(resolved)
+    )
 
 
 def _can_traverse_tool_path(resolved: str) -> bool:
@@ -357,6 +371,8 @@ def _resolve_tool_path(raw_path: str) -> str:
         raise ValueError(
             f"path '{raw_path}' is inside the application state directory"
         )
+    if _is_hardlinked_regular_file(resolved):
+        raise ValueError(f"path '{raw_path}' is a hard-linked file")
 
     for root in _tool_path_roots():
         if resolved == root:
@@ -396,6 +412,8 @@ def _resolve_tool_path_in_workspace(workspace: str, raw_path: str) -> str:
         raise ValueError(
             f"path '{raw_path}' is inside the application state directory"
         )
+    if _is_hardlinked_regular_file(resolved):
+        raise ValueError(f"path '{raw_path}' is a hard-linked file")
     if resolved != base:
         # normcase so containment holds on case-insensitive filesystems
         # (Windows, default macOS): it lowercases on Windows and is a no-op on

tests/test_agent_state_dir_confinement.py

@@ -102,6 +102,39 @@ def test_blocks_app_state_reached_through_a_symlink(tmp_path):
         _resolve_tool_path(str(link / "sessions.json"))
 
 
+def test_native_file_tools_hide_control_plane_hardlink_alias(tmp_path, monkeypatch):
+    """A pathname inside an allowed root must not alias a protected state inode."""
+    data_dir = tmp_path / "data"
+    data_dir.mkdir()
+    readable = _configure_test_data_tree(monkeypatch, data_dir)
+    workspace = readable["AGENT_WORKSPACE_DIR"]
+    workspace.mkdir()
+    secret = data_dir / "sessions.json"
+    secret.write_text("LIVE_ADMIN_SESSION\n", encoding="utf-8")
+    alias = workspace / "notes.txt"
+    try:
+        os.link(secret, alias)
+    except OSError:
+        pytest.skip("cannot create hardlink")
+
+    with pytest.raises(ValueError, match="hard-linked"):
+        importlib.import_module("src.tool_execution")._resolve_tool_path(str(alias))
+
+    ls_result = asyncio.run(LsTool().execute(
+        f'{{"path": "{workspace}"}}', {}
+    ))
+    glob_result = asyncio.run(GlobTool().execute(
+        f'{{"pattern": "**/*", "path": "{workspace}"}}', {}
+    ))
+    grep_result = asyncio.run(GrepTool().execute(
+        f'{{"pattern": "LIVE_ADMIN_SESSION", "path": "{workspace}"}}', {}
+    ))
+    assert "notes.txt" not in ls_result["output"]
+    assert "notes.txt" not in glob_result["output"]
+    assert "notes.txt" not in grep_result["output"]
+    assert ":1:LIVE_ADMIN_SESSION" not in grep_result["output"]
+
+
 def test_blocks_app_state_on_a_case_insensitive_filesystem():
     """On default macOS a case-variant path opens the same file, and realpath
     does not canonicalise case there the way it does on Windows.
@@ -120,6 +153,33 @@ def test_default_search_root_is_the_agent_workspace():
     assert _resolve_search_root("") == os.path.realpath(AGENT_WORKSPACE_DIR)
 
 
+def test_startup_rejects_agent_workspace_symlink_escape(tmp_path, monkeypatch):
+    """Startup must not accept a dedicated workspace redirected outside DATA_DIR."""
+    import src.app_initializer as app_initializer
+    import src.tool_execution as tool_execution
+
+    data_dir = tmp_path / "data"
+    outside = tmp_path / "outside"
+    data_dir.mkdir()
+    outside.mkdir()
+    workspace = data_dir / "agent_workspace"
+    try:
+        workspace.symlink_to(outside, target_is_directory=True)
+    except OSError:
+        pytest.skip("cannot create symlink")
+
+    personal = data_dir / "personal_docs"
+    monkeypatch.setattr(app_initializer, "DATA_DIR", str(data_dir))
+    monkeypatch.setattr(app_initializer, "PERSONAL_DIR", str(personal))
+    monkeypatch.setattr(app_initializer, "RUNBOOK_DIR", str(personal / "runbook"))
+    monkeypatch.setattr(app_initializer, "UPLOAD_DIR", str(data_dir / "uploads"))
+    monkeypatch.setattr(app_initializer, "AGENT_WORKSPACE_DIR", str(workspace))
+    monkeypatch.setattr(tool_execution, "AGENT_WORKSPACE_DIR", str(workspace))
+
+    with pytest.raises(RuntimeError, match="real directory"):
+        app_initializer.create_directories()
+
+
 def test_agent_workspace_is_inside_the_data_directory():
     """It has to stay under data/ to be covered by the Docker bind mount,
     so the guard cannot simply be 'anything under DATA_DIR is denied'."""