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Issue #13703: add a way to randomize the hash values of basic types (str, bytes, datetime) 

in order to make algorithmic complexity attacks on (e.g.) web apps much more complicated.

The environment variable PYTHONHASHSEED and the new command line flag -R control this
behavior.
This commit is contained in:
Georg Brandl 2012-02-20 19:54:16 +01:00
parent ec1712a166
commit 2daf6ae249
32 changed files with 660 additions and 152 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Doc/library/sys.rst
View File

@ -220,8 +220,12 @@ always available.
:const:`ignore_environment` :option:`-E`
:const:`verbose` :option:`-v`
:const:`bytes_warning` :option:`-b`
:const:`hash_randomization` :option:`-R`
============================= =============================
.. versionadded:: 3.1.5
The ``hash_randomization`` attribute.
.. data:: float_info

2
Doc/reference/datamodel.rst
View File

@ -1265,6 +1265,8 @@ Basic customization
inheritance of :meth:`__hash__` will be blocked, just as if :attr:`__hash__`
had been explicitly set to :const:`None`.
See also the :option:`-R` command-line option.
.. method:: object.__bool__(self)

48
Doc/using/cmdline.rst
View File

@ -21,7 +21,7 @@ Command line
When invoking Python, you may specify any of these options::
python [-bBdEhiOsSuvVWx?] [-c command | -m module-name | script | - ] [args]
python [-bBdEhiORsSuvVWx?] [-c command | -m module-name | script | - ] [args]
The most common use case is, of course, a simple invocation of a script::
@ -215,6 +215,29 @@ Miscellaneous options
Discard docstrings in addition to the :option:`-O` optimizations.
.. cmdoption:: -R
Turn on hash randomization, so that the :meth:`__hash__` values of str, bytes
and datetime objects are "salted" with an unpredictable random value.
Although they remain constant within an individual Python process, they are
not predictable between repeated invocations of Python.
This is intended to provide protection against a denial-of-service caused by
carefully-chosen inputs that exploit the worst case performance of a dict
insertion, O(n^2) complexity. See
http://www.ocert.org/advisories/ocert-2011-003.html for details.
Changing hash values affects the order in which keys are retrieved from a
dict. Although Python has never made guarantees about this ordering (and it
typically varies between 32-bit and 64-bit builds), enough real-world code
implicitly relies on this non-guaranteed behavior that the randomization is
disabled by default.
See also :envvar:`PYTHONHASHSEED`.
.. versionadded:: 3.1.5
.. cmdoption:: -s
Don't add user site directory to sys.path
@ -314,6 +337,7 @@ Miscellaneous options
.. note:: The line numbers in error messages will be off by one.
Options you shouldn't use
~~~~~~~~~~~~~~~~~~~~~~~~~
@ -328,6 +352,7 @@ Options you shouldn't use
Reserved for alternative implementations of Python to use for their own
purposes.
.. _using-on-envvars:
Environment variables
@ -435,6 +460,27 @@ These environment variables influence Python's behavior.
import of source modules.
.. envvar:: PYTHONHASHSEED
If this variable is set to ``random``, the effect is the same as specifying
the :option:`-R` option: a random value is used to seed the hashes of str,
bytes and datetime objects.
If :envvar:`PYTHONHASHSEED` is set to an integer value, it is used as a fixed
seed for generating the hash() of the types covered by the hash
randomization.
Its purpose is to allow repeatable hashing, such as for selftests for the
interpreter itself, or to allow a cluster of python processes to share hash
values.
The integer must be a decimal number in the range [0,4294967295]. Specifying
the value 0 will lead to the same hash values as when hash randomization is
disabled.
.. versionadded:: 3.1.5
.. envvar:: PYTHONIOENCODING
Overrides the encoding used for stdin/stdout/stderr, in the syntax

6
Include/object.h
View File

@ -473,6 +473,12 @@ PyAPI_FUNC(void) Py_ReprLeave(PyObject *);
PyAPI_FUNC(long) _Py_HashDouble(double);
PyAPI_FUNC(long) _Py_HashPointer(void*);
typedef struct {
long prefix;
long suffix;
} _Py_HashSecret_t;
PyAPI_DATA(_Py_HashSecret_t) _Py_HashSecret;
/* Helper for passing objects to printf and the like */
#define PyObject_REPR(obj) _PyUnicode_AsString(PyObject_Repr(obj))

1
Include/pydebug.h
View File

@ -19,6 +19,7 @@ PyAPI_DATA(int) Py_DivisionWarningFlag;
PyAPI_DATA(int) Py_DontWriteBytecodeFlag;
PyAPI_DATA(int) Py_NoUserSiteDirectory;
PyAPI_DATA(int) Py_UnbufferedStdioFlag;
PyAPI_DATA(int) Py_HashRandomizationFlag;
/* this is a wrapper around getenv() that pays attention to
Py_IgnoreEnvironmentFlag. It should be used for getting variables like

2
Include/pythonrun.h
View File

@ -174,6 +174,8 @@ typedef void (*PyOS_sighandler_t)(int);
PyAPI_FUNC(PyOS_sighandler_t) PyOS_getsig(int);
PyAPI_FUNC(PyOS_sighandler_t) PyOS_setsig(int, PyOS_sighandler_t);
/* Random */
PyAPI_FUNC(int) _PyOS_URandom (void *buffer, Py_ssize_t size);
#ifdef __cplusplus
}

4
Lib/json/__init__.py
View File

@ -31,7 +31,9 @@ Encoding basic Python object hierarchies::
Compact encoding::
>>> import json
>>> json.dumps([1,2,3,{'4': 5, '6': 7}], separators=(',', ':'))
>>> from collections import OrderedDict
>>> mydict = OrderedDict([('4', 5), ('6', 7)])
>>> json.dumps([1,2,3,mydict], separators=(',', ':'))
'[1,2,3,{"4":5,"6":7}]'
Pretty printing::

17
Lib/os.py
View File

@ -611,23 +611,6 @@ try:
except NameError: # statvfs_result may not exist
pass
if not _exists("urandom"):
def urandom(n):
"""urandom(n) -> str
Return a string of n random bytes suitable for cryptographic use.
"""
try:
_urandomfd = open("/dev/urandom", O_RDONLY)
except (OSError, IOError):
raise NotImplementedError("/dev/urandom (or equivalent) not found")
bs = b""
while len(bs) < n:
bs += read(_urandomfd, n - len(bs))
close(_urandomfd)
return bs
# Supply os.popen()
def popen(cmd, mode="r", buffering=-1):
if not isinstance(cmd, str):

2
Lib/test/mapping_tests.py
View File

@ -14,7 +14,7 @@ class BasicTestMappingProtocol(unittest.TestCase):
def _reference(self):
"""Return a dictionary of values which are invariant by storage
in the object under test."""
return {1:2, "key1":"value1", "key2":(1,2,3)}
return {"1": "2", "key1":"value1", "key2":(1,2,3)}
def _empty_mapping(self):
"""Return an empty mapping object"""
return self.type2test()

5
Lib/test/regrtest.py
View File

@ -428,6 +428,11 @@ def main(tests=None, testdir=None, verbose=0, quiet=False, generate=False,
except ValueError:
print("Couldn't find starting test (%s), using all tests" % start)
if randomize:
hashseed = os.getenv('PYTHONHASHSEED')
if not hashseed:
os.environ['PYTHONHASHSEED'] = str(random_seed)
os.execv(sys.executable, [sys.executable] + sys.argv)
return
random.seed(random_seed)
print("Using random seed", random_seed)
random.shuffle(tests)

7
Lib/test/script_helper.py
View File

@ -3,7 +3,6 @@
import sys
import os
import re
import os.path
import tempfile
import subprocess
@ -19,11 +18,15 @@ def _assert_python(expected_success, *args, **env_vars):
cmd_line = [sys.executable]
if not env_vars:
cmd_line.append('-E')
cmd_line.extend(args)
# Need to preserve the original environment, for in-place testing of
# shared library builds.
env = os.environ.copy()
# But a special flag that can be set to override -- in this case, the
# caller is responsible to pass the full environment.
if env_vars.pop('__cleanenv', None):
env = {}
env.update(env_vars)
cmd_line.extend(args)
p = subprocess.Popen(cmd_line, stdin=subprocess.PIPE,
stdout=subprocess.PIPE, stderr=subprocess.PIPE,
env=env)

17
Lib/test/test_cmd_line.py
View File

@ -4,7 +4,6 @@
import os
import test.support, unittest
import os
import sys
import subprocess
@ -190,6 +189,22 @@ sys.stdout.buffer.write(path)"""
self.assertTrue(path1.encode('ascii') in stdout)
self.assertTrue(path2.encode('ascii') in stdout)
def test_hash_randomization(self):
# Verify that -R enables hash randomization:
self.verify_valid_flag('-R')
hashes = []
for i in range(2):
code = 'print(hash("spam"))'
data, rc = self.start_python_and_exit_code('-R', '-c', code)
self.assertEqual(rc, 0)
hashes.append(data)
self.assertNotEqual(hashes[0], hashes[1])
# Verify that sys.flags contains hash_randomization
code = 'import sys; print("random is", sys.flags.hash_randomization)'
data, rc = self.start_python_and_exit_code('-R', '-c', code)
self.assertEqual(rc, 0)
self.assertIn(b'random is 1', data)
def test_main():
test.support.run_unittest(CmdLineTest)

12
Lib/test/test_descr.py
View File

@ -4300,8 +4300,18 @@ class DictProxyTests(unittest.TestCase):
def test_repr(self):
# Testing dict_proxy.__repr__
def sorted_dict_repr(repr_):
# Given the repr of a dict, sort the keys
assert repr_.startswith('{')
assert repr_.endswith('}')
kvs = repr_[1:-1].split(', ')
return '{' + ', '.join(sorted(kvs)) + '}'
dict_ = {k: v for k, v in self.C.__dict__.items()}
self.assertEqual(repr(self.C.__dict__), 'dict_proxy({!r})'.format(dict_))
repr_ = repr(self.C.__dict__)
self.assert_(repr_.startswith('dict_proxy('))
self.assert_(repr_.endswith(')'))
self.assertEqual(sorted_dict_repr(repr_[len('dict_proxy('):-len(')')]),
sorted_dict_repr('{!r}'.format(dict_)))
class PTypesLongInitTest(unittest.TestCase):

92
Lib/test/test_hash.py
View File

@ -3,10 +3,16 @@
#
# Also test that hash implementations are inherited as expected
import datetime
import os
import struct
import unittest
from test import support
from test.script_helper import assert_python_ok
from collections import Hashable
IS_64BIT = (struct.calcsize('l') == 8)
class HashEqualityTestCase(unittest.TestCase):
@ -118,10 +124,92 @@ class HashBuiltinsTestCase(unittest.TestCase):
for obj in self.hashes_to_check:
self.assertEqual(hash(obj), _default_hash(obj))
class HashRandomizationTests(unittest.TestCase):
# Each subclass should define a field "repr_", containing the repr() of
# an object to be tested
def get_hash_command(self, repr_):
return 'print(hash(%s))' % repr_
def get_hash(self, repr_, seed=None):
env = os.environ.copy()
env['__cleanenv'] = True # signal to assert_python not to do a copy
# of os.environ on its own
if seed is not None:
env['PYTHONHASHSEED'] = str(seed)
else:
env.pop('PYTHONHASHSEED', None)
out = assert_python_ok(
'-c', self.get_hash_command(repr_),
**env)
stdout = out[1].strip()
return int(stdout)
def test_randomized_hash(self):
# two runs should return different hashes
run1 = self.get_hash(self.repr_, seed='random')
run2 = self.get_hash(self.repr_, seed='random')
self.assertNotEqual(run1, run2)
class StringlikeHashRandomizationTests(HashRandomizationTests):
def test_null_hash(self):
# PYTHONHASHSEED=0 disables the randomized hash
if IS_64BIT:
known_hash_of_obj = 1453079729188098211
else:
known_hash_of_obj = -1600925533
# Randomization is disabled by default:
self.assertEqual(self.get_hash(self.repr_), known_hash_of_obj)
# It can also be disabled by setting the seed to 0:
self.assertEqual(self.get_hash(self.repr_, seed=0), known_hash_of_obj)
def test_fixed_hash(self):
# test a fixed seed for the randomized hash
# Note that all types share the same values:
if IS_64BIT:
h = -4410911502303878509
else:
h = -206076799
self.assertEqual(self.get_hash(self.repr_, seed=42), h)
class StrHashRandomizationTests(StringlikeHashRandomizationTests):
repr_ = repr('abc')
def test_empty_string(self):
self.assertEqual(hash(""), 0)
class BytesHashRandomizationTests(StringlikeHashRandomizationTests):
repr_ = repr(b'abc')
def test_empty_string(self):
self.assertEqual(hash(b""), 0)
class DatetimeTests(HashRandomizationTests):
def get_hash_command(self, repr_):
return 'import datetime; print(hash(%s))' % repr_
class DatetimeDateTests(DatetimeTests):
repr_ = repr(datetime.date(1066, 10, 14))
class DatetimeDatetimeTests(DatetimeTests):
repr_ = repr(datetime.datetime(1, 2, 3, 4, 5, 6, 7))
class DatetimeTimeTests(DatetimeTests):
repr_ = repr(datetime.time(0))
def test_main():
support.run_unittest(HashEqualityTestCase,
HashInheritanceTestCase,
HashBuiltinsTestCase)
HashInheritanceTestCase,
HashBuiltinsTestCase,
StrHashRandomizationTests,
BytesHashRandomizationTests,
DatetimeDateTests,
DatetimeDatetimeTests,
DatetimeTimeTests)
if __name__ == "__main__":

36
Lib/test/test_os.py
View File

@ -9,6 +9,7 @@ import warnings
import sys
import shutil
from test import support
from test.script_helper import assert_python_ok
# Detect whether we're on a Linux system that uses the (now outdated
# and unmaintained) linuxthreads threading library. There's an issue
@ -574,14 +575,33 @@ class DevNullTests(unittest.TestCase):
f.close()
class URandomTests(unittest.TestCase):
def test_urandom(self):
try:
self.assertEqual(len(os.urandom(1)), 1)
self.assertEqual(len(os.urandom(10)), 10)
self.assertEqual(len(os.urandom(100)), 100)
self.assertEqual(len(os.urandom(1000)), 1000)
except NotImplementedError:
pass
def test_urandom_length(self):
self.assertEqual(len(os.urandom(0)), 0)
self.assertEqual(len(os.urandom(1)), 1)
self.assertEqual(len(os.urandom(10)), 10)
self.assertEqual(len(os.urandom(100)), 100)
self.assertEqual(len(os.urandom(1000)), 1000)
def test_urandom_value(self):
data1 = os.urandom(16)
data2 = os.urandom(16)
self.assertNotEqual(data1, data2)
def get_urandom_subprocess(self, count):
code = '\n'.join((
'import os, sys',
'data = os.urandom(%s)' % count,
'sys.stdout.buffer.write(data)',
'sys.stdout.buffer.flush()'))
out = assert_python_ok('-c', code)
stdout = out[1]
self.assertEqual(len(stdout), 16)
return stdout
def test_urandom_subprocess(self):
data1 = self.get_urandom_subprocess(16)
data2 = self.get_urandom_subprocess(16)
self.assertNotEqual(data1, data2)
class ExecTests(unittest.TestCase):
@unittest.skipIf(USING_LINUXTHREADS,

23
Lib/test/test_set.py
View File

@ -734,6 +734,17 @@ class TestBasicOps(unittest.TestCase):
if self.repr is not None:
self.assertEqual(repr(self.set), self.repr)
def check_repr_against_values(self):
text = repr(self.set)
self.assertTrue(text.startswith('{'))
self.assertTrue(text.endswith('}'))
result = text[1:-1].split(', ')
result.sort()
sorted_repr_values = [repr(value) for value in self.values]
sorted_repr_values.sort()
self.assertEqual(result, sorted_repr_values)
def test_print(self):
try:
fo = open(support.TESTFN, "w")
@ -892,7 +903,9 @@ class TestBasicOpsString(TestBasicOps):
self.set = set(self.values)
self.dup = set(self.values)
self.length = 3
self.repr = "{'a', 'c', 'b'}"
def test_repr(self):
self.check_repr_against_values()
#------------------------------------------------------------------------------
@ -903,7 +916,9 @@ class TestBasicOpsBytes(TestBasicOps):
self.set = set(self.values)
self.dup = set(self.values)
self.length = 3
self.repr = "{b'a', b'c', b'b'}"
def test_repr(self):
self.check_repr_against_values()
#------------------------------------------------------------------------------
@ -916,11 +931,13 @@ class TestBasicOpsMixedStringBytes(TestBasicOps):
self.set = set(self.values)
self.dup = set(self.values)
self.length = 4
self.repr = "{'a', b'a', 'b', b'b'}"
def tearDown(self):
warnings.filters = self.warning_filters
def test_repr(self):
self.check_repr_against_values()
#==============================================================================
def baditer():

2
Lib/test/test_sys.py
View File

@ -446,7 +446,7 @@ class SysModuleTest(unittest.TestCase):
attrs = ("debug", "division_warning",
"inspect", "interactive", "optimize", "dont_write_bytecode",
"no_user_site", "no_site", "ignore_environment", "verbose",
"bytes_warning")
"bytes_warning", "hash_randomization")
for attr in attrs:
self.assertTrue(hasattr(sys.flags, attr), attr)
self.assertEqual(type(getattr(sys.flags, attr)), int, attr)

4
Lib/test/test_urllib.py
View File

@ -12,6 +12,7 @@ import os
import sys
import tempfile
import warnings
import collections
def hexescape(char):
"""Escape char as RFC 2396 specifies"""
@ -840,8 +841,9 @@ class urlencode_Tests(unittest.TestCase):
self.assertEqual("a=1&a=2", urllib.parse.urlencode({"a": [1, 2]}, True))
self.assertEqual("a=None&a=a",
urllib.parse.urlencode({"a": [None, "a"]}, True))
data = collections.OrderedDict([("a", 1), ("b", 1)])
self.assertEqual("a=a&a=b",
urllib.parse.urlencode({"a": {"a": 1, "b": 1}}, True))
urllib.parse.urlencode({"a": data}, True))
def test_urlencode_encoding(self):
# ASCII encoding. Expect %3F with errors="replace'

2
Lib/tkinter/test/test_ttk/test_functions.py
View File

@ -143,7 +143,7 @@ class InternalFunctionsTest(unittest.TestCase):
('a', 'b', 'c')), ("test {a b} c", ()))
# state spec and options
self.assertEqual(ttk._format_elemcreate('image', False, 'test',
('a', 'b'), a='x', b='y'), ("test a b", ("-a", "x", "-b", "y")))
('a', 'b'), a='x'), ("test a b", ("-a", "x")))
# format returned values as a tcl script
# state spec with multiple states and an option with a multivalue
self.assertEqual(ttk._format_elemcreate('image', True, 'test',

1
Makefile.pre.in
View File

@ -305,6 +305,7 @@ PYTHON_OBJS= \
Python/pymath.o \
Python/pystate.o \
Python/pythonrun.o \
Python/random.o \
Python/structmember.o \
Python/symtable.o \
Python/sysmodule.o \

5
Misc/NEWS
View File

@ -10,6 +10,11 @@ What's New in Python 3.1.5?
Core and Builtins
-----------------
- Issue #13703: oCERT-2011-003: add -R command-line option and PYTHONHASHSEED
environment variables, to provide an opt-in way to protect against denial of
service attacks due to hash collisions within the dict and set types. Patch
by David Malcolm, based on work by Victor Stinner.
Library
-------

29
Misc/python.man
View File

@ -34,6 +34,9 @@ python \- an interpreted, interactive, object-oriented programming language
.B \-OO
]
[
.B \-R
]
[
.B -Q
.I argument
]
@ -145,6 +148,18 @@ to \fI.pyo\fP. Given twice, causes docstrings to be discarded.
.B \-OO
Discard docstrings in addition to the \fB-O\fP optimizations.
.TP
.B \-R
Turn on "hash randomization", so that the hash() values of str, bytes and
datetime objects are "salted" with an unpredictable pseudo-random value.
Although they remain constant within an individual Python process, they are
not predictable between repeated invocations of Python.
.IP
This is intended to provide protection against a denial of service
caused by carefully-chosen inputs that exploit the worst case performance
of a dict insertion, O(n^2) complexity. See
http://www.ocert.org/advisories/ocert-2011-003.html
for details.
.TP
.BI "\-Q " argument
Division control; see PEP 238. The argument must be one of "old" (the
default, int/int and long/long return an int or long), "new" (new
@ -403,6 +418,20 @@ the \fB\-u\fP option.
If this is set to a non-empty string it is equivalent to specifying
the \fB\-v\fP option. If set to an integer, it is equivalent to
specifying \fB\-v\fP multiple times.
.IP PYTHONHASHSEED
If this variable is set to "random", the effect is the same as specifying
the \fB-R\fP option: a random value is used to seed the hashes of str,
bytes and datetime objects.
If PYTHONHASHSEED is set to an integer value, it is used as a fixed seed for
generating the hash() of the types covered by the hash randomization. Its
purpose is to allow repeatable hashing, such as for selftests for the
interpreter itself, or to allow a cluster of python processes to share hash
values.
The integer must be a decimal number in the range [0,4294967295]. Specifying
the value 0 will lead to the same hash values as when hash randomization is
disabled.
.SH AUTHOR
The Python Software Foundation: http://www.python.org/psf
.SH INTERNET RESOURCES

4
Modules/datetimemodule.c
View File

@ -2566,10 +2566,12 @@ generic_hash(unsigned char *data, int len)
register long x;
p = (unsigned char *) data;
x = *p << 7;
x = _Py_HashSecret.prefix;
x ^= *p << 7;
while (--len >= 0)
x = (1000003*x) ^ *p++;
x ^= len;
x ^= _Py_HashSecret.suffix;
if (x == -1)
x = -2;

16
Modules/main.c
View File

@ -47,7 +47,7 @@ static wchar_t **orig_argv;
static int orig_argc;
/* command line options */
#define BASE_OPTS L"bBc:dEhiJm:OsStuvVW:xX?"
#define BASE_OPTS L"bBc:dEhiJm:ORsStuvVW:xX?"
#define PROGRAM_OPTS BASE_OPTS
@ -72,6 +72,9 @@ static char *usage_2 = "\
-m mod : run library module as a script (terminates option list)\n\
-O : optimize generated bytecode slightly; also PYTHONOPTIMIZE=x\n\
-OO : remove doc-strings in addition to the -O optimizations\n\
-R : use a pseudo-random salt to make hash() values of various types be\n\
unpredictable between separate invocations of the interpreter, as\n\
a defence against denial-of-service attacks\n\
-s : don't add user site directory to sys.path; also PYTHONNOUSERSITE\n\
-S : don't imply 'import site' on initialization\n\
";
@ -99,6 +102,12 @@ PYTHONHOME : alternate <prefix> directory (or <prefix>%c<exec_prefix>).\n\
PYTHONCASEOK : ignore case in 'import' statements (Windows).\n\
PYTHONIOENCODING: Encoding[:errors] used for stdin/stdout/stderr.\n\
";
static char *usage_6 = "\
PYTHONHASHSEED: if this variable is set to ``random``, the effect is the same \n\
as specifying the :option:`-R` option: a random value is used to seed the\n\
hashes of str, bytes and datetime objects. It can also be set to an integer\n\
in the range [0,4294967295] to get hash values with a predictable seed.\n\
";
#ifndef MS_WINDOWS
static FILE*
@ -136,6 +145,7 @@ usage(int exitcode, wchar_t* program)
fputs(usage_3, f);
fprintf(f, usage_4, DELIM);
fprintf(f, usage_5, DELIM, PYTHONHOMEHELP);
fputs(usage_6, f);
}
#if defined(__VMS)
if (exitcode == 0) {
@ -373,6 +383,10 @@ Py_Main(int argc, wchar_t **argv)
PySys_AddWarnOption(_PyOS_optarg);
break;
case 'R':
Py_HashRandomizationFlag++;
break;
/* This space reserved for other options */
default:

125
Modules/posixmodule.c
View File

@ -4022,7 +4022,7 @@ posix_getgroups(PyObject *self, PyObject *noargs)
#endif
gid_t grouplist[MAX_GROUPS];
/* On MacOSX getgroups(2) can return more than MAX_GROUPS results
/* On MacOSX getgroups(2) can return more than MAX_GROUPS results
* This is a helper variable to store the intermediate result when
* that happens.
*
@ -6942,82 +6942,6 @@ posix_getloadavg(PyObject *self, PyObject *noargs)
}
#endif
#ifdef MS_WINDOWS
PyDoc_STRVAR(win32_urandom__doc__,
"urandom(n) -> str\n\n\
Return n random bytes suitable for cryptographic use.");
typedef BOOL (WINAPI *CRYPTACQUIRECONTEXTA)(HCRYPTPROV *phProv,\
LPCSTR pszContainer, LPCSTR pszProvider, DWORD dwProvType,\
DWORD dwFlags );
typedef BOOL (WINAPI *CRYPTGENRANDOM)(HCRYPTPROV hProv, DWORD dwLen,\
BYTE *pbBuffer );
static CRYPTGENRANDOM pCryptGenRandom = NULL;
/* This handle is never explicitly released. Instead, the operating
system will release it when the process terminates. */
static HCRYPTPROV hCryptProv = 0;
static PyObject*
win32_urandom(PyObject *self, PyObject *args)
{
int howMany;
PyObject* result;
/* Read arguments */
if (! PyArg_ParseTuple(args, "i:urandom", &howMany))
return NULL;
if (howMany < 0)
return PyErr_Format(PyExc_ValueError,
"negative argument not allowed");
if (hCryptProv == 0) {
HINSTANCE hAdvAPI32 = NULL;
CRYPTACQUIRECONTEXTA pCryptAcquireContext = NULL;
/* Obtain handle to the DLL containing CryptoAPI
This should not fail */
hAdvAPI32 = GetModuleHandle("advapi32.dll");
if(hAdvAPI32 == NULL)
return win32_error("GetModuleHandle", NULL);
/* Obtain pointers to the CryptoAPI functions
This will fail on some early versions of Win95 */
pCryptAcquireContext = (CRYPTACQUIRECONTEXTA)GetProcAddress(
hAdvAPI32,
"CryptAcquireContextA");
if (pCryptAcquireContext == NULL)
return PyErr_Format(PyExc_NotImplementedError,
"CryptAcquireContextA not found");
pCryptGenRandom = (CRYPTGENRANDOM)GetProcAddress(
hAdvAPI32, "CryptGenRandom");
if (pCryptGenRandom == NULL)
return PyErr_Format(PyExc_NotImplementedError,
"CryptGenRandom not found");
/* Acquire context */
if (! pCryptAcquireContext(&hCryptProv, NULL, NULL,
PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
return win32_error("CryptAcquireContext", NULL);
}
/* Allocate bytes */
result = PyBytes_FromStringAndSize(NULL, howMany);
if (result != NULL) {
/* Get random data */
memset(PyBytes_AS_STRING(result), 0, howMany); /* zero seed */
if (! pCryptGenRandom(hCryptProv, howMany, (unsigned char*)
PyBytes_AS_STRING(result))) {
Py_DECREF(result);
return win32_error("CryptGenRandom", NULL);
}
}
return result;
}
#endif
PyDoc_STRVAR(device_encoding__doc__,
"device_encoding(fd) -> str\n\n\
Return a string describing the encoding of the device\n\
@ -7055,41 +6979,35 @@ device_encoding(PyObject *self, PyObject *args)
return Py_None;
}
#ifdef __VMS
/* Use openssl random routine */
#include <openssl/rand.h>
PyDoc_STRVAR(vms_urandom__doc__,
PyDoc_STRVAR(posix_urandom__doc__,
"urandom(n) -> str\n\n\
Return n random bytes suitable for cryptographic use.");
static PyObject*
vms_urandom(PyObject *self, PyObject *args)
static PyObject *
posix_urandom(PyObject *self, PyObject *args)
{
int howMany;
PyObject* result;
Py_ssize_t size;
PyObject *result;
int ret;
/* Read arguments */
if (! PyArg_ParseTuple(args, "i:urandom", &howMany))
/* Read arguments */
if (!PyArg_ParseTuple(args, "n:urandom", &size))
return NULL;
if (howMany < 0)
if (size < 0)
return PyErr_Format(PyExc_ValueError,
"negative argument not allowed");
result = PyBytes_FromStringAndSize(NULL, size);
if (result == NULL)
return NULL;
/* Allocate bytes */
result = PyBytes_FromStringAndSize(NULL, howMany);
if (result != NULL) {
/* Get random data */
if (RAND_pseudo_bytes((unsigned char*)
PyBytes_AS_STRING(result),
howMany) < 0) {
Py_DECREF(result);
return PyErr_Format(PyExc_ValueError,
"RAND_pseudo_bytes");
}
ret = _PyOS_URandom(PyBytes_AS_STRING(result),
PyBytes_GET_SIZE(result));
if (ret == -1) {
Py_DECREF(result);
return NULL;
}
return result;
}
#endif
static PyMethodDef posix_methods[] = {
{"access", posix_access, METH_VARARGS, posix_access__doc__},
@ -7374,12 +7292,7 @@ static PyMethodDef posix_methods[] = {
#ifdef HAVE_GETLOADAVG
{"getloadavg", posix_getloadavg, METH_NOARGS, posix_getloadavg__doc__},
#endif
#ifdef MS_WINDOWS
{"urandom", win32_urandom, METH_VARARGS, win32_urandom__doc__},
#endif
#ifdef __VMS
{"urandom", vms_urandom, METH_VARARGS, vms_urandom__doc__},
#endif
{"urandom", posix_urandom, METH_VARARGS, posix_urandom__doc__},
{NULL, NULL} /* Sentinel */
};

12
Objects/bytesobject.c
View File

@ -899,11 +899,21 @@ bytes_hash(PyBytesObject *a)
if (a->ob_shash != -1)
return a->ob_shash;
len = Py_SIZE(a);
/*
We make the hash of the empty string be 0, rather than using
(prefix ^ suffix), since this slightly obfuscates the hash secret
*/
if (len == 0) {
a->ob_shash = 0;
return 0;
}
p = (unsigned char *) a->ob_sval;
x = *p << 7;
x = _Py_HashSecret.prefix;
x ^= *p << 7;
while (--len >= 0)
x = (1000003*x) ^ *p++;
x ^= Py_SIZE(a);
x ^= _Py_HashSecret.suffix;
if (x == -1)
x = -2;
a->ob_shash = x;

2
Objects/object.c
View File

@ -712,6 +712,8 @@ PyObject_HashNotImplemented(PyObject *v)
return -1;
}
_Py_HashSecret_t _Py_HashSecret;
long
PyObject_Hash(PyObject *v)
{

12
Objects/unicodeobject.c
View File

@ -7344,11 +7344,21 @@ unicode_hash(PyUnicodeObject *self)
if (self->hash != -1)
return self->hash;
len = Py_SIZE(self);
/*
We make the hash of the empty string be 0, rather than using
(prefix ^ suffix), since this slightly obfuscates the hash secret
*/
if (len == 0) {
self->hash = 0;
return 0;
}
p = self->str;
x = *p << 7;
x = _Py_HashSecret.prefix;
x ^= *p << 7;
while (--len >= 0)
x = (1000003*x) ^ *p++;
x ^= Py_SIZE(self);
x ^= _Py_HashSecret.suffix;
if (x == -1)
x = -2;
self->hash = x;

4
PCbuild/pythoncore.vcproj
View File

@ -1778,6 +1778,10 @@
RelativePath="..\Python\pythonrun.c"
>
</File>
<File
RelativePath="..\Python\random.c"
>
</File>
<File
RelativePath="..\Python\structmember.c"
>

8
Python/pythonrun.c
View File

@ -73,6 +73,7 @@ extern void _PyUnicode_Init(void);
extern void _PyUnicode_Fini(void);
extern int _PyLong_Init(void);
extern void PyLong_Fini(void);
extern void _PyRandom_Init(void);
#ifdef WITH_THREAD
extern void _PyGILState_Init(PyInterpreterState *, PyThreadState *);
@ -91,6 +92,7 @@ int Py_FrozenFlag; /* Needed by getpath.c */
int Py_IgnoreEnvironmentFlag; /* e.g. PYTHONPATH, PYTHONHOME */
int Py_NoUserSiteDirectory = 0; /* for -s and site.py */
int Py_UnbufferedStdioFlag = 0; /* Unbuffered binary std{in,out,err} */
int Py_HashRandomizationFlag = 0; /* for -R and PYTHONHASHSEED */
/* PyModule_GetWarningsModule is no longer necessary as of 2.6
since _warnings is builtin. This API should not be used. */
@ -195,6 +197,12 @@ Py_InitializeEx(int install_sigs)
Py_OptimizeFlag = add_flag(Py_OptimizeFlag, p);
if ((p = Py_GETENV("PYTHONDONTWRITEBYTECODE")) && *p != '\0')
Py_DontWriteBytecodeFlag = add_flag(Py_DontWriteBytecodeFlag, p);
/* The variable is only tested for existence here; _PyRandom_Init will
check its value further. */
if ((p = Py_GETENV("PYTHONHASHSEED")) && *p != '\0')
Py_HashRandomizationFlag = add_flag(Py_HashRandomizationFlag, p);
_PyRandom_Init();
interp = PyInterpreterState_New();
if (interp == NULL)

302
Python/random.c Normal file
View File

@ -0,0 +1,302 @@
#include "Python.h"
#ifdef MS_WINDOWS
#include <windows.h>
#else
#include <fcntl.h>
#endif
static int random_initialized = 0;
#ifdef MS_WINDOWS
typedef BOOL (WINAPI *CRYPTACQUIRECONTEXTA)(HCRYPTPROV *phProv,\
LPCSTR pszContainer, LPCSTR pszProvider, DWORD dwProvType,\
DWORD dwFlags );
typedef BOOL (WINAPI *CRYPTGENRANDOM)(HCRYPTPROV hProv, DWORD dwLen,\
BYTE *pbBuffer );
static CRYPTGENRANDOM pCryptGenRandom = NULL;
/* This handle is never explicitly released. Instead, the operating
system will release it when the process terminates. */
static HCRYPTPROV hCryptProv = 0;
static int
win32_urandom_init(int raise)
{
HINSTANCE hAdvAPI32 = NULL;
CRYPTACQUIRECONTEXTA pCryptAcquireContext = NULL;
/* Obtain handle to the DLL containing CryptoAPI. This should not fail. */
hAdvAPI32 = GetModuleHandle("advapi32.dll");
if(hAdvAPI32 == NULL)
goto error;
/* Obtain pointers to the CryptoAPI functions. This will fail on some early
versions of Win95. */
pCryptAcquireContext = (CRYPTACQUIRECONTEXTA)GetProcAddress(
hAdvAPI32, "CryptAcquireContextA");
if (pCryptAcquireContext == NULL)
goto error;
pCryptGenRandom = (CRYPTGENRANDOM)GetProcAddress(hAdvAPI32,
"CryptGenRandom");
if (pCryptGenRandom == NULL)
goto error;
/* Acquire context */
if (! pCryptAcquireContext(&hCryptProv, NULL, NULL,
PROV_RSA_FULL, CRYPT_VERIFYCONTEXT))
goto error;
return 0;
error:
if (raise)
PyErr_SetFromWindowsErr(0);
else
Py_FatalError("Failed to initialize Windows random API (CryptoGen)");
return -1;
}
/* Fill buffer with size pseudo-random bytes generated by the Windows CryptoGen
API. Return 0 on success, or -1 on error. */
static int
win32_urandom(unsigned char *buffer, Py_ssize_t size, int raise)
{
Py_ssize_t chunk;
if (hCryptProv == 0)
{
if (win32_urandom_init(raise) == -1)
return -1;
}
while (size > 0)
{
chunk = size > INT_MAX ? INT_MAX : size;
if (!pCryptGenRandom(hCryptProv, chunk, buffer))
{
/* CryptGenRandom() failed */
if (raise)
PyErr_SetFromWindowsErr(0);
else
Py_FatalError("Failed to initialized the randomized hash "
"secret using CryptoGen)");
return -1;
}
buffer += chunk;
size -= chunk;
}
return 0;
}
#endif /* MS_WINDOWS */
#ifdef __VMS
/* Use openssl random routine */
#include <openssl/rand.h>
static int
vms_urandom(unsigned char *buffer, Py_ssize_t size, int raise)
{
if (RAND_pseudo_bytes(buffer, size) < 0) {
if (raise) {
PyErr_Format(PyExc_ValueError,
"RAND_pseudo_bytes");
} else {
Py_FatalError("Failed to initialize the randomized hash "
"secret using RAND_pseudo_bytes");
}
return -1;
}
return 0;
}
#endif /* __VMS */
#if !defined(MS_WINDOWS) && !defined(__VMS)
/* Read size bytes from /dev/urandom into buffer.
Call Py_FatalError() on error. */
static void
dev_urandom_noraise(char *buffer, Py_ssize_t size)
{
int fd;
Py_ssize_t n;
assert (0 < size);
fd = open("/dev/urandom", O_RDONLY);
if (fd < 0)
Py_FatalError("Failed to open /dev/urandom");
while (0 < size)
{
do {
n = read(fd, buffer, (size_t)size);
} while (n < 0 && errno == EINTR);
if (n <= 0)
{
/* stop on error or if read(size) returned 0 */
Py_FatalError("Failed to read bytes from /dev/urandom");
break;
}
buffer += n;
size -= (Py_ssize_t)n;
}
close(fd);
}
/* Read size bytes from /dev/urandom into buffer.
Return 0 on success, raise an exception and return -1 on error. */
static int
dev_urandom_python(char *buffer, Py_ssize_t size)
{
int fd;
Py_ssize_t n;
if (size <= 0)
return 0;
Py_BEGIN_ALLOW_THREADS
fd = open("/dev/urandom", O_RDONLY);
Py_END_ALLOW_THREADS
if (fd < 0)
{
PyErr_SetFromErrnoWithFilename(PyExc_OSError, "/dev/urandom");
return -1;
}
Py_BEGIN_ALLOW_THREADS
do {
do {
n = read(fd, buffer, (size_t)size);
} while (n < 0 && errno == EINTR);
if (n <= 0)
break;
buffer += n;
size -= (Py_ssize_t)n;
} while (0 < size);
Py_END_ALLOW_THREADS
if (n <= 0)
{
/* stop on error or if read(size) returned 0 */
if (n < 0)
PyErr_SetFromErrno(PyExc_OSError);
else
PyErr_Format(PyExc_RuntimeError,
"Failed to read %zi bytes from /dev/urandom",
size);
close(fd);
return -1;
}
close(fd);
return 0;
}
#endif /* !defined(MS_WINDOWS) && !defined(__VMS) */
/* Fill buffer with pseudo-random bytes generated by a linear congruent
generator (LCG):
x(n+1) = (x(n) * 214013 + 2531011) % 2^32
Use bits 23..16 of x(n) to generate a byte. */
static void
lcg_urandom(unsigned int x0, unsigned char *buffer, size_t size)
{
size_t index;
unsigned int x;
x = x0;
for (index=0; index < size; index++) {
x *= 214013;
x += 2531011;
/* modulo 2 ^ (8 * sizeof(int)) */
buffer[index] = (x >> 16) & 0xff;
}
}
/* Fill buffer with size pseudo-random bytes, not suitable for cryptographic
use, from the operating random number generator (RNG).
Return 0 on success, raise an exception and return -1 on error. */
int
_PyOS_URandom(void *buffer, Py_ssize_t size)
{
if (size < 0) {
PyErr_Format(PyExc_ValueError,
"negative argument not allowed");
return -1;
}
if (size == 0)
return 0;
#ifdef MS_WINDOWS
return win32_urandom((unsigned char *)buffer, size, 1);
#else
# ifdef __VMS
return vms_urandom((unsigned char *)buffer, size, 1);
# else
return dev_urandom_python((char*)buffer, size);
# endif
#endif
}
void
_PyRandom_Init(void)
{
char *env;
void *secret = &_Py_HashSecret;
Py_ssize_t secret_size = sizeof(_Py_HashSecret);
if (random_initialized)
return;
random_initialized = 1;
/*
By default, hash randomization is disabled, and only
enabled if PYTHONHASHSEED is set to non-empty or if
"-R" is provided at the command line:
*/
if (!Py_HashRandomizationFlag) {
/* Disable the randomized hash: */
memset(secret, 0, secret_size);
return;
}
/*
Hash randomization is enabled. Generate a per-process secret,
using PYTHONHASHSEED if provided.
*/
env = Py_GETENV("PYTHONHASHSEED");
if (env && *env != '\0' & strcmp(env, "random") != 0) {
char *endptr = env;
unsigned long seed;
seed = strtoul(env, &endptr, 10);
if (*endptr != '\0'
|| seed > 4294967295UL
|| (errno == ERANGE && seed == ULONG_MAX))
{
Py_FatalError("PYTHONHASHSEED must be \"random\" or an integer "
"in range [0; 4294967295]");
}
if (seed == 0) {
/* disable the randomized hash */
memset(secret, 0, secret_size);
}
else {
lcg_urandom(seed, (unsigned char*)secret, secret_size);
}
}
else {
#ifdef MS_WINDOWS
(void)win32_urandom((unsigned char *)secret, secret_size, 0);
#else /* #ifdef MS_WINDOWS */
# ifdef __VMS
vms_urandom((unsigned char *)secret, secret_size, 0);
# else
dev_urandom_noraise((char*)secret, secret_size);
# endif
#endif
}
}

6
Python/sysmodule.c
View File

@ -1126,6 +1126,7 @@ static PyStructSequence_Field flags_fields[] = {
/* {"unbuffered", "-u"}, */
/* {"skip_first", "-x"}, */
{"bytes_warning", "-b"},
{"hash_randomization", "-R"},
{0}
};
@ -1134,9 +1135,9 @@ static PyStructSequence_Desc flags_desc = {
flags__doc__, /* doc */
flags_fields, /* fields */
#ifdef RISCOS
12
13
#else
11
12
#endif
};
@ -1169,6 +1170,7 @@ make_flags(void)
/* SetFlag(saw_unbuffered_flag); */
/* SetFlag(skipfirstline); */
SetFlag(Py_BytesWarningFlag);
SetFlag(Py_HashRandomizationFlag);
#undef SetFlag
if (PyErr_Occurred()) {