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Backport patch to fix CVE-2020-25657.
Upstream-Status: Backport [https://gitlab.com/m2crypto/m2crypto/-/commit/84c53958]
Signed-off-by: Kai Kang <kai.kang@windriver.com>
From 84c53958def0f510e92119fca14d74f94215827a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mat=C4=9Bj=20Cepl?= <mcepl@cepl.eu>
Date: Tue, 28 Jun 2022 21:17:01 +0200
Subject: [PATCH] Mitigate the Bleichenbacher timing attacks in the RSA
decryption API (CVE-2020-25657)
Fixes #282
---
src/SWIG/_m2crypto_wrap.c | 20 ++++++++++++--------
src/SWIG/_rsa.i | 20 ++++++++++++--------
tests/test_rsa.py | 15 +++++++--------
3 files changed, 31 insertions(+), 24 deletions(-)
diff --git a/src/SWIG/_m2crypto_wrap.c b/src/SWIG/_m2crypto_wrap.c
index aba9eb6d..a9f30da9 100644
--- a/src/SWIG/_m2crypto_wrap.c
+++ b/src/SWIG/_m2crypto_wrap.c
@@ -7040,9 +7040,10 @@ PyObject *rsa_private_encrypt(RSA *rsa, PyObject *from, int padding) {
tlen = RSA_private_encrypt(flen, (unsigned char *)fbuf,
(unsigned char *)tbuf, rsa, padding);
if (tlen == -1) {
- m2_PyErr_Msg(_rsa_err);
+ ERR_clear_error();
+ PyErr_Clear();
PyMem_Free(tbuf);
- return NULL;
+ Py_RETURN_NONE;
}
ret = PyBytes_FromStringAndSize((const char *)tbuf, tlen);
@@ -7070,9 +7071,10 @@ PyObject *rsa_public_decrypt(RSA *rsa, PyObject *from, int padding) {
tlen = RSA_public_decrypt(flen, (unsigned char *)fbuf,
(unsigned char *)tbuf, rsa, padding);
if (tlen == -1) {
- m2_PyErr_Msg(_rsa_err);
+ ERR_clear_error();
+ PyErr_Clear();
PyMem_Free(tbuf);
- return NULL;
+ Py_RETURN_NONE;
}
ret = PyBytes_FromStringAndSize((const char *)tbuf, tlen);
@@ -7097,9 +7099,10 @@ PyObject *rsa_public_encrypt(RSA *rsa, PyObject *from, int padding) {
tlen = RSA_public_encrypt(flen, (unsigned char *)fbuf,
(unsigned char *)tbuf, rsa, padding);
if (tlen == -1) {
- m2_PyErr_Msg(_rsa_err);
+ ERR_clear_error();
+ PyErr_Clear();
PyMem_Free(tbuf);
- return NULL;
+ Py_RETURN_NONE;
}
ret = PyBytes_FromStringAndSize((const char *)tbuf, tlen);
@@ -7124,9 +7127,10 @@ PyObject *rsa_private_decrypt(RSA *rsa, PyObject *from, int padding) {
tlen = RSA_private_decrypt(flen, (unsigned char *)fbuf,
(unsigned char *)tbuf, rsa, padding);
if (tlen == -1) {
- m2_PyErr_Msg(_rsa_err);
+ ERR_clear_error();
+ PyErr_Clear();
PyMem_Free(tbuf);
- return NULL;
+ Py_RETURN_NONE;
}
ret = PyBytes_FromStringAndSize((const char *)tbuf, tlen);
diff --git a/src/SWIG/_rsa.i b/src/SWIG/_rsa.i
index bc714e01..1377b8be 100644
--- a/src/SWIG/_rsa.i
+++ b/src/SWIG/_rsa.i
@@ -239,9 +239,10 @@ PyObject *rsa_private_encrypt(RSA *rsa, PyObject *from, int padding) {
tlen = RSA_private_encrypt(flen, (unsigned char *)fbuf,
(unsigned char *)tbuf, rsa, padding);
if (tlen == -1) {
- m2_PyErr_Msg(_rsa_err);
+ ERR_clear_error();
+ PyErr_Clear();
PyMem_Free(tbuf);
- return NULL;
+ Py_RETURN_NONE;
}
ret = PyBytes_FromStringAndSize((const char *)tbuf, tlen);
@@ -269,9 +270,10 @@ PyObject *rsa_public_decrypt(RSA *rsa, PyObject *from, int padding) {
tlen = RSA_public_decrypt(flen, (unsigned char *)fbuf,
(unsigned char *)tbuf, rsa, padding);
if (tlen == -1) {
- m2_PyErr_Msg(_rsa_err);
+ ERR_clear_error();
+ PyErr_Clear();
PyMem_Free(tbuf);
- return NULL;
+ Py_RETURN_NONE;
}
ret = PyBytes_FromStringAndSize((const char *)tbuf, tlen);
@@ -296,9 +298,10 @@ PyObject *rsa_public_encrypt(RSA *rsa, PyObject *from, int padding) {
tlen = RSA_public_encrypt(flen, (unsigned char *)fbuf,
(unsigned char *)tbuf, rsa, padding);
if (tlen == -1) {
- m2_PyErr_Msg(_rsa_err);
+ ERR_clear_error();
+ PyErr_Clear();
PyMem_Free(tbuf);
- return NULL;
+ Py_RETURN_NONE;
}
ret = PyBytes_FromStringAndSize((const char *)tbuf, tlen);
@@ -323,9 +326,10 @@ PyObject *rsa_private_decrypt(RSA *rsa, PyObject *from, int padding) {
tlen = RSA_private_decrypt(flen, (unsigned char *)fbuf,
(unsigned char *)tbuf, rsa, padding);
if (tlen == -1) {
- m2_PyErr_Msg(_rsa_err);
+ ERR_clear_error();
+ PyErr_Clear();
PyMem_Free(tbuf);
- return NULL;
+ Py_RETURN_NONE;
}
ret = PyBytes_FromStringAndSize((const char *)tbuf, tlen);
diff --git a/tests/test_rsa.py b/tests/test_rsa.py
index 7bb3af75..5e75d681 100644
--- a/tests/test_rsa.py
+++ b/tests/test_rsa.py
@@ -109,8 +109,9 @@ class RSATestCase(unittest.TestCase):
# The other paddings.
for padding in self.s_padding_nok:
p = getattr(RSA, padding)
- with self.assertRaises(RSA.RSAError):
- priv.private_encrypt(self.data, p)
+ # Exception disabled as a part of mitigation against CVE-2020-25657
+ # with self.assertRaises(RSA.RSAError):
+ priv.private_encrypt(self.data, p)
# Type-check the data to be encrypted.
with self.assertRaises(TypeError):
priv.private_encrypt(self.gen_callback, RSA.pkcs1_padding)
@@ -127,10 +128,12 @@ class RSATestCase(unittest.TestCase):
self.assertEqual(ptxt, self.data)
# no_padding
- with six.assertRaisesRegex(self, RSA.RSAError, 'data too small'):
- priv.public_encrypt(self.data, RSA.no_padding)
+ # Exception disabled as a part of mitigation against CVE-2020-25657
+ # with six.assertRaisesRegex(self, RSA.RSAError, 'data too small'):
+ priv.public_encrypt(self.data, RSA.no_padding)
# Type-check the data to be encrypted.
+ # Exception disabled as a part of mitigation against CVE-2020-25657
with self.assertRaises(TypeError):
priv.public_encrypt(self.gen_callback, RSA.pkcs1_padding)
@@ -146,10 +149,6 @@ class RSATestCase(unittest.TestCase):
b'\000\000\000\003\001\000\001') # aka 65537 aka 0xf4
with self.assertRaises(RSA.RSAError):
setattr(rsa, 'e', '\000\000\000\003\001\000\001')
- with self.assertRaises(RSA.RSAError):
- rsa.private_encrypt(1)
- with self.assertRaises(RSA.RSAError):
- rsa.private_decrypt(1)
assert rsa.check_key()
def test_loadpub_bad(self):
--
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