python3-m2crypto: fix for CVE-2020-25657

A flaw was found in all released versions of m2crypto, where they are
vulnerable to Bleichenbacher timing attacks in the RSA decryption API
via the timed processing of valid PKCS#1 v1.5 Ciphertext. The highest
threat from this vulnerability is to confidentiality.

Signed-off-by: Narpat Mali <narpat.mali@windriver.com>
Signed-off-by: Armin Kuster <akuster808@gmail.com>

2 files changed, 176 insertions, 0 deletions

diff --git a/meta-python/recipes-devtools/python/python3-m2crypto/CVE-2020-25657.patch b/meta-python/recipes-devtools/python/python3-m2crypto/CVE-2020-25657.patch
new file mode 100644
index 0000000000..cc915f1478
--- /dev/null
+++ b/meta-python/recipes-devtools/python/python3-m2crypto/CVE-2020-25657.patch
@@ -0,0 +1,175 @@
+From 2fa92e048b76fcc7bf2d4f4443478c8292d17470 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Mat=C4=9Bj=20Cepl?= <mcepl@cepl.eu>
+Date: Thu, 1 Jun 2023 14:56:34 +0000
+Subject: [PATCH] Mitigate the Bleichenbacher timing attacks in the RSA
+ decryption API (CVE-2020-25657)
+
+Fixes #282
+
+CVE: CVE-2020-25657
+
+Upstream-Status: Backport [https://gitlab.com/m2crypto/m2crypto/-/commit/84c53958def0f510e92119fca14d74f94215827a]
+
+Signed-off-by: Narpat Mali <narpat.mali@windriver.com>
+---
+ 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 3db88b9..6aafe1f 100644
+--- a/src/SWIG/_m2crypto_wrap.c
++++ b/src/SWIG/_m2crypto_wrap.c
+@@ -7129,9 +7129,10 @@ 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);
+@@ -7159,9 +7160,10 @@ 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);
+@@ -7186,9 +7188,10 @@ 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);
+@@ -7213,9 +7216,10 @@ 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 bc714e0..1377b8b 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 7bb3af7..5e75d68 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):
+--
+2.40.0
diff --git a/meta-python/recipes-devtools/python/python3-m2crypto_0.38.0.bb b/meta-python/recipes-devtools/python/python3-m2crypto_0.38.0.bb
index 51a0dd676e..155a9066ca 100644
--- a/meta-python/recipes-devtools/python/python3-m2crypto_0.38.0.bb
+++ b/meta-python/recipes-devtools/python/python3-m2crypto_0.38.0.bb
@@ -10,6 +10,7 @@ SRC_URI += "file://0001-setup.py-link-in-sysroot-not-in-host-directories.patch \
            file://cross-compile-platform.patch \
            file://avoid-host-contamination.patch \
            file://0001-setup.py-address-openssl-3.x-build-issue.patch \
+           file://CVE-2020-25657.patch \
            "
 SRC_URI[sha256sum] = "99f2260a30901c949a8dc6d5f82cd5312ffb8abc92e76633baf231bbbcb2decb"