At Barry's suggestion, plug the security leak by using an empty
__builtins__ for all calls to eval(). This still allows someone to
write string.atof("[1]*1000000") (which Jim Fulton worries about) but
effectively disables access to system modules and functions.
diff --git a/Lib/string.py b/Lib/string.py
index 8c64952..c0f5147 100644
--- a/Lib/string.py
+++ b/Lib/string.py
@@ -198,6 +198,9 @@
i = i+1
return r
+# "Safe" environment for eval()
+safe_env = {"__builtins__": {}}
+
# Convert string to float
re = None
def atof(str):
@@ -219,7 +222,7 @@
if re and not re.match('[0-9]*(\.[0-9]*)?([eE][-+]?[0-9]+)?$', s):
raise ValueError, 'non-float argument to string.atof'
try:
- return float(eval(sign + s, {}))
+ return float(eval(sign + s, safe_env))
except SyntaxError:
raise ValueError, 'non-float argument to string.atof'
@@ -239,7 +242,7 @@
for c in s:
if c not in digits:
raise ValueError, 'non-integer argument to string.atoi'
- return eval(sign + s)
+ return eval(sign + s, safe_env)
# Convert string to long integer
def atol(str, base=10):
@@ -257,7 +260,7 @@
for c in s:
if c not in digits:
raise ValueError, 'non-integer argument to string.atol'
- return eval(sign + s + 'L')
+ return eval(sign + s + 'L', safe_env)
# Left-justify a string
def ljust(s, width):