File size: 8,338 Bytes
388137e | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 | """Safe SQLite Read-Only Executor with authorizer callback and execution timeout."""
import sqlite3
import time
from dataclasses import dataclass, field
from pathlib import Path
from typing import Any, List, Optional, Tuple
import sqlglot
from src.t2s.safety.policy import SafetyPolicy
@dataclass
class ExecutionResult:
success: bool
columns: List[str] = field(default_factory=list)
rows: List[Tuple[Any, ...]] = field(default_factory=list)
row_count: int = 0
execution_time_ms: float = 0.0
truncated: bool = False
error: Optional[str] = None
def _sqlite_authorizer(
action_code: int, arg1: Any, arg2: Any, db_name: Any, trigger_name: Any
) -> int:
"""Authorizer callback for SQLite connection level defense."""
# SQLITE_OK = 0, SQLITE_DENY = 1, SQLITE_IGNORE = 2
# Allowed actions for read-only query execution
allowed_codes = {
sqlite3.SQLITE_SELECT,
sqlite3.SQLITE_READ,
sqlite3.SQLITE_FUNCTION,
}
if action_code in allowed_codes:
return sqlite3.SQLITE_OK
return sqlite3.SQLITE_DENY
class SafeSQLExecutor:
def __init__(
self,
timeout_seconds: float = 3.0,
max_rows: int = 100,
policy: Optional[SafetyPolicy] = None,
) -> None:
self.timeout_seconds = timeout_seconds
self.max_rows = max_rows
self.policy = policy or SafetyPolicy.load()
def execute_read_only(
self,
db_path: str,
sql: str,
canonical_only: bool = True,
) -> ExecutionResult:
p = Path(db_path)
if not p.exists():
return ExecutionResult(success=False, error=f"Database file does not exist: {db_path}")
# Task D2.a: Execute canonical re-serialized SQL from sqlglot, never unparsed raw strings
exec_sql = sql
if canonical_only and sql and sql.strip():
try:
parsed = sqlglot.parse_one(sql.strip().rstrip(";"), read="sqlite")
exec_sql = parsed.sql(dialect="sqlite")
if not exec_sql.endswith(";"):
exec_sql += ";"
except Exception as e:
return ExecutionResult(success=False, error=f"Canonical SQL formatting error: {e}")
# Connect strictly in read-only mode using URI syntax
uri_path = f"file:{p.resolve().as_posix()}?mode=ro"
start_time = time.perf_counter()
conn = None
try:
conn = sqlite3.connect(uri_path, uri=True, timeout=self.timeout_seconds)
# Defensive engine configs (Task D2.e)
if hasattr(conn, "enable_load_extension"):
try:
conn.enable_load_extension(False)
except Exception:
pass
for cfg_name, cfg_val in [
("SQLITE_DBCONFIG_DEFENSIVE", True),
("SQLITE_DBCONFIG_ENABLE_FTS3_TOKENIZER", False),
("SQLITE_DBCONFIG_TRUSTED_SCHEMA", False),
]:
if hasattr(sqlite3, cfg_name) and hasattr(conn, "setconfig"):
try:
conn.setconfig(getattr(sqlite3, cfg_name), cfg_val)
except Exception:
pass
# Enforce read-only at connection PRAGMA level
conn.execute("PRAGMA query_only = ON;")
# Authorizer as ground truth (Task D2.c)
denied_tbls = {t.lower() for t in self.policy.denied_tables}
denied_cols = {c.lower() for c in self.policy.denied_columns}
allowed_funcs = {f.lower() for f in self.policy.allowed_functions}
denied_funcs = {f.lower() for f in self.policy.denied_functions}
def authorizer_callback(
action_code: int, arg1: Any, arg2: Any, db_name: Any, trigger_name: Any
) -> int:
# Disallow PRAGMA (19) and ATTACH (24)
if action_code in (
getattr(sqlite3, "SQLITE_PRAGMA", 19),
getattr(sqlite3, "SQLITE_ATTACH", 24),
getattr(sqlite3, "SQLITE_DETACH", 25),
):
return sqlite3.SQLITE_DENY
# Allow SELECT root actions
if action_code == sqlite3.SQLITE_SELECT:
return sqlite3.SQLITE_OK
# Check table/column reads (SQLITE_READ = 20)
if action_code == sqlite3.SQLITE_READ:
tbl = str(arg1).lower() if arg1 else ""
col = str(arg2).lower() if arg2 else ""
if tbl in denied_tbls:
return sqlite3.SQLITE_DENY
if col in denied_cols:
return sqlite3.SQLITE_DENY
for dc in denied_cols:
if col == dc or col.startswith(f"{dc}_") or col.endswith(f"_{dc}"):
return sqlite3.SQLITE_DENY
return sqlite3.SQLITE_OK
# Check function execution (SQLITE_FUNCTION = 31)
if action_code == sqlite3.SQLITE_FUNCTION:
fn_name = str(arg2).lower() if arg2 else ""
if denied_funcs and fn_name in denied_funcs:
return sqlite3.SQLITE_DENY
if allowed_funcs and fn_name not in allowed_funcs:
return sqlite3.SQLITE_DENY
return sqlite3.SQLITE_OK
# Deny all other actions (DML, DDL, recursive CTEs, etc.)
return sqlite3.SQLITE_DENY
conn.set_authorizer(authorizer_callback)
# Set defensive connection limits
for limit_name, limit_val in [
("SQLITE_LIMIT_LENGTH", 10_000_000), # 10 MB maximum string / blob length
("SQLITE_LIMIT_SQL_LENGTH", 100_000), # 100 KB max SQL length
("SQLITE_LIMIT_EXPR_DEPTH", 200), # Max expression tree depth
("SQLITE_LIMIT_COMPOUND_SELECT", 50), # Max compound SELECT terms
]:
if hasattr(sqlite3, limit_name) and hasattr(conn, "setlimit"):
try:
conn.setlimit(getattr(sqlite3, limit_name), limit_val)
except Exception:
pass
# Install progress handler for query execution timeout control
start_ticks = time.perf_counter()
timeout_sec = self.timeout_seconds
def progress_callback() -> int:
if (time.perf_counter() - start_ticks) > timeout_sec:
return 1 # Non-zero returns abort query
return 0
conn.set_progress_handler(progress_callback, 100)
cursor = conn.cursor()
cursor.execute(exec_sql)
columns = [desc[0] for desc in cursor.description] if cursor.description else []
fetched_rows = cursor.fetchmany(self.max_rows + 1)
truncated = False
if len(fetched_rows) > self.max_rows:
truncated = True
rows = fetched_rows[: self.max_rows]
else:
rows = fetched_rows
exec_time = (time.perf_counter() - start_time) * 1000.0
return ExecutionResult(
success=True,
columns=columns,
rows=rows,
row_count=len(rows),
execution_time_ms=round(exec_time, 2),
truncated=truncated,
error=None,
)
except sqlite3.DatabaseError as e:
exec_time = (time.perf_counter() - start_time) * 1000.0
return ExecutionResult(
success=False,
execution_time_ms=round(exec_time, 2),
error=f"SQLite Security/Execution error: {e}",
)
except Exception as e:
exec_time = (time.perf_counter() - start_time) * 1000.0
return ExecutionResult(
success=False,
execution_time_ms=round(exec_time, 2),
error=f"Execution error: {e}",
)
finally:
if conn:
try:
conn.close()
except Exception:
pass
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