Fixes to safe_eval

pull/6811/head
James Cammarata 11 years ago
parent 6a1dcca4be
commit a4df906fc9

@ -29,6 +29,7 @@ from ansible.utils.plugins import *
from ansible.utils import template
from ansible.callbacks import display
import ansible.constants as C
import ast
import time
import StringIO
import stat
@ -974,51 +975,95 @@ def is_list_of_strings(items):
return False
return True
def safe_eval(str, locals=None, include_exceptions=False):
def safe_eval(expr, locals={}, include_exceptions=False):
'''
this is intended for allowing things like:
with_items: a_list_variable
where Jinja2 would return a string
but we do not want to allow it to call functions (outside of Jinja2, where
the env is constrained)
Based on:
http://stackoverflow.com/questions/12523516/using-ast-and-whitelists-to-make-pythons-eval-safe
'''
# FIXME: is there a more native way to do this?
def is_set(var):
return not var.startswith("$") and not '{{' in var
# this is the whitelist of AST nodes we are going to
# allow in the evaluation. Any node type other than
# those listed here will raise an exception in our custom
# visitor class defined below.
SAFE_NODES = set(
(
ast.Expression,
ast.Compare,
ast.Str,
ast.List,
ast.Tuple,
ast.Dict,
ast.Call,
ast.Load,
ast.BinOp,
ast.UnaryOp,
ast.Num,
ast.Name,
ast.Add,
ast.Sub,
ast.Mult,
ast.Div,
)
)
# AST node types were expanded after 2.6
if not sys.version.startswith('2.6'):
SAFE_NODES.union(
set(
(ast.Set,)
)
)
def is_unset(var):
return var.startswith("$") or '{{' in var
# builtin functions that are not safe to call
INVALID_CALLS = (
'classmethod', 'compile', 'delattr', 'eval', 'execfile', 'file',
'filter', 'help', 'input', 'object', 'open', 'raw_input', 'reduce',
'reload', 'repr', 'setattr', 'staticmethod', 'super', 'type',
)
# do not allow method calls to modules
if not isinstance(str, basestring):
class CleansingNodeVisitor(ast.NodeVisitor):
def generic_visit(self, node):
if type(node) not in SAFE_NODES:
#raise Exception("invalid expression (%s) type=%s" % (expr, type(node)))
raise Exception("invalid expression (%s)" % expr)
super(CleansingNodeVisitor, self).generic_visit(node)
def visit_Call(self, call):
if call.func.id in INVALID_CALLS:
raise Exception("invalid function: %s" % call.func.id)
if not isinstance(expr, basestring):
# already templated to a datastructure, perhaps?
if include_exceptions:
return (str, None)
return str
if re.search(r'\w\.\w+\(', str):
if include_exceptions:
return (str, None)
return str
# do not allow imports
if re.search(r'import \w+', str):
if include_exceptions:
return (str, None)
return str
return (expr, None)
return expr
try:
result = None
if not locals:
result = eval(str)
else:
result = eval(str, None, locals)
parsed_tree = ast.parse(expr, mode='eval')
cnv = CleansingNodeVisitor()
cnv.visit(parsed_tree)
compiled = compile(parsed_tree, expr, 'eval')
result = eval(compiled, {}, locals)
if include_exceptions:
return (result, None)
else:
return result
except SyntaxError, e:
# special handling for syntax errors, we just return
# the expression string back as-is
if include_exceptions:
return (expr, None)
return expr
except Exception, e:
if include_exceptions:
return (str, e)
return str
return (expr, e)
return expr
def listify_lookup_plugin_terms(terms, basedir, inject):
@ -1030,7 +1075,7 @@ def listify_lookup_plugin_terms(terms, basedir, inject):
# with_items: {{ alist }}
stripped = terms.strip()
if not (stripped.startswith('{') or stripped.startswith('[')) and not stripped.startswith("/"):
if not (stripped.startswith('{') or stripped.startswith('[')) and not stripped.startswith("/") and not stripped.startswith('set(['):
# if not already a list, get ready to evaluate with Jinja2
# not sure why the "/" is in above code :)
try:

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