1 # -*- coding: utf-8 -*-
2 ##############################################################################
3 # Copyright (C) 2004-2012 OpenERP s.a. (<http://www.openerp.com>).
5 # This program is free software: you can redistribute it and/or modify
6 # it under the terms of the GNU Affero General Public License as
7 # published by the Free Software Foundation, either version 3 of the
8 # License, or (at your option) any later version.
10 # This program is distributed in the hope that it will be useful,
11 # but WITHOUT ANY WARRANTY; without even the implied warranty of
12 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 # GNU Affero General Public License for more details.
15 # You should have received a copy of the GNU Affero General Public License
16 # along with this program. If not, see <http://www.gnu.org/licenses/>.
18 ##############################################################################
21 safe_eval module - methods intended to provide more restricted alternatives to
22 evaluate simple and/or untrusted code.
24 Methods in this module are typically used as alternatives to eval() to parse
25 OpenERP domain strings, conditions and expressions, mostly based on locals
26 condition/math builtins.
29 # Module partially ripped from/inspired by several different sources:
30 # - http://code.activestate.com/recipes/286134/
31 # - safe_eval in lp:~xrg/openobject-server/optimize-5.0
32 # - safe_eval in tryton http://hg.tryton.org/hgwebdir.cgi/trytond/rev/bbb5f73319ad
34 from opcode import HAVE_ARGUMENT, opmap, opname
35 from types import CodeType
38 from .misc import ustr
42 __all__ = ['test_expr', 'safe_eval', 'const_eval']
44 # The time module is usually already provided in the safe_eval environment
45 # but some code, e.g. datetime.datetime.now() (Windows/Python 2.5.2, bug
46 # lp:703841), does import time.
47 _ALLOWED_MODULES = ['_strptime', 'time']
49 _CONST_OPCODES = set(opmap[x] for x in [
50 'POP_TOP', 'ROT_TWO', 'ROT_THREE', 'ROT_FOUR', 'DUP_TOP', 'DUP_TOPX',
51 'POP_BLOCK','SETUP_LOOP', 'BUILD_LIST', 'BUILD_MAP', 'BUILD_TUPLE',
52 'LOAD_CONST', 'RETURN_VALUE', 'STORE_SUBSCR', 'STORE_MAP'] if x in opmap)
54 _EXPR_OPCODES = _CONST_OPCODES.union(set(opmap[x] for x in [
55 'UNARY_POSITIVE', 'UNARY_NEGATIVE', 'UNARY_NOT',
56 'UNARY_INVERT', 'BINARY_POWER', 'BINARY_MULTIPLY',
57 'BINARY_DIVIDE', 'BINARY_FLOOR_DIVIDE', 'BINARY_TRUE_DIVIDE',
58 'BINARY_MODULO', 'BINARY_ADD', 'BINARY_SUBTRACT', 'BINARY_SUBSCR',
59 'BINARY_LSHIFT', 'BINARY_RSHIFT', 'BINARY_AND', 'BINARY_XOR',
60 'BINARY_OR', 'INPLACE_ADD', 'INPLACE_SUBTRACT', 'INPLACE_MULTIPLY',
61 'INPLACE_DIVIDE', 'INPLACE_REMAINDER', 'INPLACE_POWER',
62 'INPLACE_LEFTSHIFT', 'INPLACE_RIGHTSHIFT', 'INPLACE_AND',
63 'INPLACE_XOR','INPLACE_OR'
66 _SAFE_OPCODES = _EXPR_OPCODES.union(set(opmap[x] for x in [
67 'LOAD_NAME', 'CALL_FUNCTION', 'COMPARE_OP', 'LOAD_ATTR',
68 'STORE_NAME', 'GET_ITER', 'FOR_ITER', 'LIST_APPEND', 'DELETE_NAME',
69 'JUMP_FORWARD', 'JUMP_IF_TRUE', 'JUMP_IF_FALSE', 'JUMP_ABSOLUTE',
70 'MAKE_FUNCTION', 'SLICE+0', 'SLICE+1', 'SLICE+2', 'SLICE+3',
71 # New in Python 2.7 - http://bugs.python.org/issue4715 :
72 'JUMP_IF_FALSE_OR_POP', 'JUMP_IF_TRUE_OR_POP', 'POP_JUMP_IF_FALSE',
73 'POP_JUMP_IF_TRUE', 'SETUP_EXCEPT', 'END_FINALLY'
76 _logger = logging.getLogger(__name__)
78 def _get_opcodes(codeobj):
79 """_get_opcodes(codeobj) -> [opcodes]
81 Extract the actual opcodes as a list from a code object
83 >>> c = compile("[1 + 2, (1,2)]", "", "eval")
85 [100, 100, 23, 100, 100, 102, 103, 83]
89 byte_codes = codeobj.co_code
90 while i < len(byte_codes):
91 code = ord(byte_codes[i])
93 if code >= HAVE_ARGUMENT:
99 def test_expr(expr, allowed_codes, mode="eval"):
100 """test_expr(expression, allowed_codes[, mode]) -> code_object
102 Test that the expression contains only the allowed opcodes.
103 If the expression is valid and contains only allowed codes,
104 return the compiled code object.
105 Otherwise raise a ValueError, a Syntax Error or TypeError accordingly.
109 # eval() does not like leading/trailing whitespace
111 code_obj = compile(expr, "", mode)
112 except (SyntaxError, TypeError):
116 exc_info = sys.exc_info()
117 raise ValueError, '"%s" while compiling\n%r' % (ustr(e), expr), exc_info[2]
118 for code in _get_opcodes(code_obj):
119 if code not in allowed_codes:
120 raise ValueError("opcode %s not allowed (%r)" % (opname[code], expr))
124 def const_eval(expr):
125 """const_eval(expression) -> value
127 Safe Python constant evaluation
129 Evaluates a string that contains an expression describing
130 a Python constant. Strings that are not valid Python expressions
131 or that contain other code besides the constant raise ValueError.
135 >>> const_eval("[1,2, (3,4), {'foo':'bar'}]")
136 [1, 2, (3, 4), {'foo': 'bar'}]
137 >>> const_eval("1+2")
138 Traceback (most recent call last):
140 ValueError: opcode BINARY_ADD not allowed
142 c = test_expr(expr, _CONST_OPCODES)
146 """expr_eval(expression) -> value
148 Restricted Python expression evaluation
150 Evaluates a string that contains an expression that only
151 uses Python constants. This can be used to e.g. evaluate
152 a numerical expression from an untrusted source.
156 >>> expr_eval("[1,2]*2")
158 >>> expr_eval("__import__('sys').modules")
159 Traceback (most recent call last):
161 ValueError: opcode LOAD_NAME not allowed
163 c = test_expr(expr, _EXPR_OPCODES)
166 def _import(name, globals=None, locals=None, fromlist=None, level=-1):
173 if name in _ALLOWED_MODULES:
174 return __import__(name, globals, locals, level)
175 raise ImportError(name)
177 def safe_eval(expr, globals_dict=None, locals_dict=None, mode="eval", nocopy=False):
178 """safe_eval(expression[, globals[, locals[, mode[, nocopy]]]]) -> result
180 System-restricted Python expression evaluation
182 Evaluates a string that contains an expression that mostly
183 uses Python constants, arithmetic expressions and the
184 objects directly provided in context.
186 This can be used to e.g. evaluate
187 an OpenERP domain expression from an untrusted source.
189 Throws TypeError, SyntaxError or ValueError (not allowed) accordingly.
191 >>> safe_eval("__import__('sys').modules")
192 Traceback (most recent call last):
194 ValueError: opcode LOAD_NAME not allowed
197 if isinstance(expr, CodeType):
198 raise ValueError("safe_eval does not allow direct evaluation of code objects.")
200 if '__subclasses__' in expr:
201 raise ValueError('expression not allowed (__subclasses__)')
203 if globals_dict is None:
206 # prevent altering the globals/locals from within the sandbox
209 # isinstance() does not work below, we want *exactly* the dict class
210 if (globals_dict is not None and type(globals_dict) is not dict) \
211 or (locals_dict is not None and type(locals_dict) is not dict):
213 "Looks like you are trying to pass a dynamic environment, "
214 "you should probably pass nocopy=True to safe_eval().")
216 globals_dict = dict(globals_dict)
217 if locals_dict is not None:
218 locals_dict = dict(locals_dict)
222 '__import__': _import,
244 c = test_expr(expr, _SAFE_OPCODES, mode=mode)
246 return eval(c, globals_dict, locals_dict)
247 except openerp.osv.orm.except_orm:
249 except openerp.exceptions.Warning:
251 except openerp.exceptions.RedirectWarning:
253 except openerp.exceptions.AccessDenied:
255 except openerp.exceptions.AccessError:
259 exc_info = sys.exc_info()
260 raise ValueError, '"%s" while evaluating\n%r' % (ustr(e), expr), exc_info[2]
262 # vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4: