P. Christeas
4afe236b0c
Regular eval() would not care about leading whitespace. But, compile() would break if lines start with space. Strip that. Also, allow some exceptions to pass through, so that we can examine the syntax errors etc. bzr revid: p_christ@hol.gr-20100621143632-0hvrck77lterxjtl
262 lines
9.1 KiB
Python
262 lines
9.1 KiB
Python
# -*- coding: utf-8 -*-
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##############################################################################
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# Copyright (C) 2004-2010 OpenERP s.a. (<http://www.openerp.com>).
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#
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# This program is free software: you can redistribute it and/or modify
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# it under the terms of the GNU Affero General Public License as
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# published by the Free Software Foundation, either version 3 of the
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# License, or (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU Affero General Public License for more details.
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#
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# You should have received a copy of the GNU Affero General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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#
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##############################################################################
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"""
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safe_eval module - methods intended to provide more restricted alternatives to
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evaluate simple and/or untrusted code.
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Methods in this module are typically used as alternatives to eval() to parse
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OpenERP domain strings, conditions and expressions, mostly based on locals
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condition/math builtins.
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"""
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# Module partially ripped from/inspired by several different sources:
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# - http://code.activestate.com/recipes/286134/
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# - safe_eval in lp:~xrg/openobject-server/optimize-5.0
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# - safe_eval in tryton http://hg.tryton.org/hgwebdir.cgi/trytond/rev/bbb5f73319ad
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# - python 2.6's ast.literal_eval
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from opcode import HAVE_ARGUMENT, opmap, opname
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from types import CodeType
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__all__ = ['test_expr', 'literal_eval', 'safe_eval', 'const_eval', 'ext_eval' ]
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_CONST_OPCODES = set(opmap[x] for x in [
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'POP_TOP', 'ROT_TWO', 'ROT_THREE', 'ROT_FOUR', 'DUP_TOP',
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'BUILD_LIST', 'BUILD_MAP', 'BUILD_TUPLE',
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'LOAD_CONST', 'RETURN_VALUE', 'STORE_SUBSCR'] if x in opmap)
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_EXPR_OPCODES = _CONST_OPCODES.union(set(opmap[x] for x in [
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'UNARY_POSITIVE', 'UNARY_NEGATIVE', 'UNARY_NOT',
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'UNARY_INVERT', 'BINARY_POWER', 'BINARY_MULTIPLY',
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'BINARY_DIVIDE', 'BINARY_FLOOR_DIVIDE', 'BINARY_TRUE_DIVIDE',
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'BINARY_MODULO', 'BINARY_ADD', 'BINARY_SUBTRACT', 'BINARY_SUBSCR',
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'BINARY_LSHIFT', 'BINARY_RSHIFT', 'BINARY_AND', 'BINARY_XOR',
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'BINARY_OR'] if x in opmap))
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_SAFE_OPCODES = _EXPR_OPCODES.union(set(opmap[x] for x in [
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'STORE_MAP', 'LOAD_NAME', 'CALL_FUNCTION', 'COMPARE_OP', 'LOAD_ATTR',
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'STORE_NAME', 'GET_ITER', 'FOR_ITER', 'LIST_APPEND', 'JUMP_ABSOLUTE',
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'DELETE_NAME', 'JUMP_IF_TRUE', 'JUMP_IF_FALSE','MAKE_FUNCTION',
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] if x in opmap))
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def _get_opcodes(codeobj):
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"""_get_opcodes(codeobj) -> [opcodes]
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Extract the actual opcodes as a list from a code object
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>>> c = compile("[1 + 2, (1,2)]", "", "eval")
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>>> _get_opcodes(c)
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[100, 100, 23, 100, 100, 102, 103, 83]
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"""
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i = 0
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opcodes = []
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byte_codes = codeobj.co_code
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while i < len(byte_codes):
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code = ord(byte_codes[i])
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opcodes.append(code)
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if code >= HAVE_ARGUMENT:
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i += 3
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else:
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i += 1
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return opcodes
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def test_expr(expr, allowed_codes, mode="eval"):
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"""test_expr(expression, allowed_codes[, mode]) -> code_object
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Test that the expression contains only the allowed opcodes.
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If the expression is valid and contains only allowed codes,
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return the compiled code object. Otherwise raise a ValueError.
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"""
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try:
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if mode == 'eval':
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expr = expr.strip()
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code_obj = compile(expr, "", mode)
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except SyntaxError:
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raise
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except TypeError:
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raise
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except Exception, e:
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raise ValueError("%s is not a valid expression" % expr)
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for code in _get_opcodes(code_obj):
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if code not in allowed_codes:
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raise ValueError("opcode %s not allowed (%r)" % (opname[code], expr))
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return code_obj
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def const_eval(expr):
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"""const_eval(expression) -> value
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Safe Python constant evaluation
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Evaluates a string that contains an expression describing
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a Python constant. Strings that are not valid Python expressions
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or that contain other code besides the constant raise ValueError.
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>>> const_eval("10")
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10
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>>> const_eval("[1,2, (3,4), {'foo':'bar'}]")
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[1, 2, (3, 4), {'foo': 'bar'}]
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>>> const_eval("1+2")
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Traceback (most recent call last):
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...
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ValueError: opcode BINARY_ADD not allowed
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"""
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c = test_expr(expr, _CONST_OPCODES)
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return eval(c)
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def expr_eval(expr):
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"""expr_eval(expression) -> value
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Restricted Python expression evaluation
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Evaluates a string that contains an expression that only
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uses Python constants. This can be used to e.g. evaluate
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a numerical expression from an untrusted source.
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>>> expr_eval("1+2")
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3
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>>> expr_eval("[1,2]*2")
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[1, 2, 1, 2]
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>>> expr_eval("__import__('sys').modules")
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Traceback (most recent call last):
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...
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ValueError: opcode LOAD_NAME not allowed
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"""
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c = test_expr(expr, _EXPR_OPCODES)
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return eval(c)
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# Port of Python 2.6's ast.literal_eval for use under Python 2.5
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SAFE_CONSTANTS = {'None': None, 'True': True, 'False': False}
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try:
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# first, try importing directly
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from ast import literal_eval
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except ImportError:
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import _ast as ast
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def _convert(node):
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if isinstance(node, ast.Str):
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return node.s
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elif isinstance(node, ast.Num):
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return node.n
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elif isinstance(node, ast.Tuple):
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return tuple(map(_convert, node.elts))
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elif isinstance(node, ast.List):
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return list(map(_convert, node.elts))
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elif isinstance(node, ast.Dict):
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return dict((_convert(k), _convert(v)) for k, v
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in zip(node.keys, node.values))
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elif isinstance(node, ast.Name):
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if node.id in SAFE_CONSTANTS:
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return SAFE_CONSTANTS[node.id]
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raise ValueError('malformed or disallowed expression')
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def parse(expr, filename='<unknown>', mode='eval'):
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"""parse(source[, filename], mode]] -> code object
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Parse an expression into an AST node.
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Equivalent to compile(expr, filename, mode, PyCF_ONLY_AST).
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"""
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return compile(expr, filename, mode, ast.PyCF_ONLY_AST)
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def literal_eval(node_or_string):
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"""literal_eval(expression) -> value
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Safely evaluate an expression node or a string containing a Python
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expression. The string or node provided may only consist of the
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following Python literal structures: strings, numbers, tuples,
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lists, dicts, booleans, and None.
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>>> literal_eval('[1,True,"spam"]')
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[1, True, 'spam']
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>>> literal_eval('1+3')
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Traceback (most recent call last):
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...
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ValueError: malformed or disallowed expression
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"""
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if isinstance(node_or_string, basestring):
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node_or_string = parse(node_or_string)
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if isinstance(node_or_string, ast.Expression):
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node_or_string = node_or_string.body
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return _convert(node_or_string)
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def safe_eval(expr, globals_dict=None, locals_dict=None, mode="eval", nocopy=False):
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"""safe_eval(expression[, globals[, locals[, mode[, nocopy]]]]) -> result
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System-restricted Python expression evaluation
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Evaluates a string that contains an expression that mostly
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uses Python constants, arithmetic expressions and the
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objects directly provided in context.
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This can be used to e.g. evaluate
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an OpenERP domain expression from an untrusted source.
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>>> safe_eval("__import__('sys').modules")
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Traceback (most recent call last):
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...
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ValueError: opcode LOAD_NAME not allowed
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"""
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if isinstance(expr, CodeType):
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raise ValueError("safe_eval does not allow direct evaluation of code objects.")
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if '__subclasses__' in expr:
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raise ValueError('expression not allowed (__subclasses__)')
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if globals_dict is None:
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globals_dict = {}
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# prevent altering the globals/locals from within the sandbox
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# by taking a copy.
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if not nocopy:
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# isinstance() does not work below, we want *exactly* the dict class
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if (globals_dict is not None and type(globals_dict) is not dict) \
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or (locals_dict is not None and type(locals_dict) is not dict):
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logging.getLogger('safe_eval').warning('Looks like you are trying to pass a dynamic environment,"\
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"you should probably pass nocopy=True to safe_eval()')
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globals_dict = dict(globals_dict)
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if locals_dict is not None:
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locals_dict = dict(locals_dict)
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globals_dict.update(
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__builtins__ = {
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'True': True,
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'False': False,
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'None': None,
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'str': str,
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'globals': locals,
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'locals': locals,
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'bool': bool,
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'dict': dict,
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'list': list,
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'tuple': tuple,
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'map' : map,
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}
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)
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return eval(test_expr(expr,_SAFE_OPCODES, mode=mode), globals_dict, locals_dict)
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# vim:expandtab:smartindent:tabstop=4:softtabstop=4:shiftwidth=4:
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