File CVE-2022-29217-non-blocked-pubkeys.patch of Package python-PyJWT

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File CVE-2022-29217-non-blocked-pubkeys.patch of Package python-PyJWT (Revision f2adf97c855701dee6b6cb96446fcccd)

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From 9c528670c455b8d948aff95ed50e22940d1ad3fc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jos=C3=A9=20Padilla?= <jpadilla@webapplicate.com>
Date: Thu, 12 May 2022 14:31:00 -0400
Subject: [PATCH] Merge pull request from GHSA-ffqj-6fqr-9h24
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Co-authored-by: José Padilla <jpadilla@users.noreply.github.com>
---
 jwt/algorithms.py      |   55 ++++++++++++------------
 jwt/api_jws.py         |    2 
 jwt/utils.py           |   61 +++++++++++++++++++++++++++
 tests/test_advisory.py |  110 +++++++++++++++++++++++++++++++++++++++++++++++++
 tests/test_api_jws.py  |    1 
 tests/test_api_jwt.py  |    1 
 6 files changed, 203 insertions(+), 27 deletions(-)
 create mode 100644 tests/test_advisory.py

--- a/jwt/algorithms.py
+++ b/jwt/algorithms.py
@@ -7,8 +7,9 @@ from .compat import constant_time_compar
 from .exceptions import InvalidKeyError
 from .utils import (
     base64url_decode, base64url_encode, der_to_raw_signature,
-    force_bytes, force_unicode, from_base64url_uint, raw_to_der_signature,
-    to_base64url_uint
+    force_bytes, force_unicode, from_base64url_uint,
+    is_pem_format, is_ssh_key,
+    raw_to_der_signature, to_base64url_uint
 )
 
 try:
@@ -139,14 +140,7 @@ class HMACAlgorithm(Algorithm):
     def prepare_key(self, key):
         key = force_bytes(key)
 
-        invalid_strings = [
-            b'-----BEGIN PUBLIC KEY-----',
-            b'-----BEGIN CERTIFICATE-----',
-            b'-----BEGIN RSA PUBLIC KEY-----',
-            b'ssh-rsa'
-        ]
-
-        if any([string_value in key for string_value in invalid_strings]):
+        if is_pem_format(key) or is_ssh_key(key):
             raise InvalidKeyError(
                 'The specified key is an asymmetric key or x509 certificate and'
                 ' should not be used as an HMAC secret.')
@@ -332,26 +326,35 @@ if has_crypto:
             self.hash_alg = hash_alg
 
         def prepare_key(self, key):
-            if isinstance(key, EllipticCurvePrivateKey) or \
-               isinstance(key, EllipticCurvePublicKey):
+            if isinstance(key, (EllipticCurvePrivateKey, EllipticCurvePublicKey)):
                 return key
 
-            if isinstance(key, string_types):
-                key = force_bytes(key)
+            if not isinstance(key, string_types):
+                raise TypeError("Expecting a PEM-formatted key.")
 
-                # Attempt to load key. We don't know if it's
-                # a Signing Key or a Verifying Key, so we try
-                # the Verifying Key first.
-                try:
-                    if key.startswith(b'ecdsa-sha2-'):
-                        key = load_ssh_public_key(key, backend=default_backend())
-                    else:
-                        key = load_pem_public_key(key, backend=default_backend())
-                except ValueError:
-                    key = load_pem_private_key(key, password=None, backend=default_backend())
+            key = force_bytes(key)
 
-            else:
-                raise TypeError('Expecting a PEM-formatted key.')
+            # Attempt to load key. We don't know if it's
+            # a Signing Key or a Verifying Key, so we try
+            # the Verifying Key first.
+            try:
+                if key.startswith(b'ecdsa-sha2-'):
+                    key = load_ssh_public_key(key,
+                                              backend=default_backend())
+                else:
+                    key = load_pem_public_key(key,
+                                              backend=default_backend())
+            except ValueError:
+                key = load_pem_private_key(key, password=None,
+                                           backend=default_backend())
+
+            # Explicit check the key to prevent confusing errors from
+            # cryptography
+            if not isinstance(key, (EllipticCurvePrivateKey,
+                                    EllipticCurvePublicKey)):
+                raise InvalidKeyError(
+                    "Expecting a EllipticCurvePrivateKey/EllipticCurvePublicKey. Wrong key provided for ECDSA algorithms"
+                )
 
             return key
 
--- a/jwt/api_jws.py
+++ b/jwt/api_jws.py
@@ -213,7 +213,7 @@ class PyJWS(object):
         alg = header.get('alg')
 
         if algorithms is not None and alg not in algorithms:
-            raise InvalidAlgorithmError('The specified alg value is not allowed')
+            raise InvalidAlgorithmError('The specified alg value %s is not allowed' % str(alg))
 
         try:
             alg_obj = self._algorithms[alg]
--- a/jwt/utils.py
+++ b/jwt/utils.py
@@ -1,5 +1,6 @@
 import base64
 import binascii
+import re
 import struct
 
 from .compat import binary_type, bytes_from_int, text_type
@@ -111,3 +112,63 @@ def raw_to_der_signature(raw_sig, curve)
     s = bytes_to_number(raw_sig[num_bytes:])
 
     return encode_dss_signature(r, s)
+
+
+# Based on https://github.com/hynek/pem/blob/7ad94db26b0bc21d10953f5dbad3acfdfacf57aa/src/pem/_core.py#L224-L252
+_PEMS = {
+    b"CERTIFICATE",
+    b"TRUSTED CERTIFICATE",
+    b"PRIVATE KEY",
+    b"PUBLIC KEY",
+    b"ENCRYPTED PRIVATE KEY",
+    b"OPENSSH PRIVATE KEY",
+    b"DSA PRIVATE KEY",
+    b"RSA PRIVATE KEY",
+    b"RSA PUBLIC KEY",
+    b"EC PRIVATE KEY",
+    b"DH PARAMETERS",
+    b"NEW CERTIFICATE REQUEST",
+    b"CERTIFICATE REQUEST",
+    b"SSH2 PUBLIC KEY",
+    b"SSH2 ENCRYPTED PRIVATE KEY",
+    b"X509 CRL",
+}
+
+_PEM_RE = re.compile(
+    b"----[- ]BEGIN ("
+    + b"|".join(_PEMS)
+    + b""")[- ]----\r?
+.+?\r?
+----[- ]END \\1[- ]----\r?\n?""",
+    re.DOTALL,
+)
+
+
+def is_pem_format(key):
+    return bool(_PEM_RE.search(key))
+
+
+# Based on https://github.com/pyca/cryptography/blob/bcb70852d577b3f490f015378c75cba74986297b/src/cryptography/hazmat/primitives/serialization/ssh.py#L40-L46
+_CERT_SUFFIX = b"-cert-v01@openssh.com"
+_SSH_PUBKEY_RC = re.compile(br"\A(\S+)[ \t]+(\S+)")
+_SSH_KEY_FORMATS = [
+    b"ssh-ed25519",
+    b"ssh-rsa",
+    b"ssh-dss",
+    b"ecdsa-sha2-nistp256",
+    b"ecdsa-sha2-nistp384",
+    b"ecdsa-sha2-nistp521",
+]
+
+
+def is_ssh_key(key):
+    if any(string_value in key for string_value in _SSH_KEY_FORMATS):
+        return True
+
+    ssh_pubkey_match = _SSH_PUBKEY_RC.match(key)
+    if ssh_pubkey_match:
+        key_type = ssh_pubkey_match.group(1)
+        if _CERT_SUFFIX == key_type[-len(_CERT_SUFFIX) :]:
+            return True
+
+    return False
--- /dev/null
+++ b/tests/test_advisory.py
@@ -0,0 +1,110 @@
+import jwt
+import pytest
+from jwt.exceptions import InvalidKeyError
+
+priv_key_bytes = b'''-----BEGIN PRIVATE KEY-----
+MC4CAQAwBQYDK2VwBCIEIIbBhdo2ah7X32i50GOzrCr4acZTe6BezUdRIixjTAdL
+-----END PRIVATE KEY-----'''
+
+pub_key_bytes = b'ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIPL1I9oiq+B8crkmuV4YViiUnhdLjCp3hvy1bNGuGfNL'
+
+ssh_priv_key_bytes = b"""-----BEGIN EC PRIVATE KEY-----
+MHcCAQEEIOWc7RbaNswMtNtc+n6WZDlUblMr2FBPo79fcGXsJlGQoAoGCCqGSM49
+AwEHoUQDQgAElcy2RSSSgn2RA/xCGko79N+7FwoLZr3Z0ij/ENjow2XpUDwwKEKk
+Ak3TDXC9U8nipMlGcY7sDpXp2XyhHEM+Rw==
+-----END EC PRIVATE KEY-----"""
+
+ssh_key_bytes = b"""ecdsa-sha2-nistp256 AAAAE2VjZHNhLXNoYTItbmlzdHAyNTYAAAAIbmlzdHAyNTYAAABBBJXMtkUkkoJ9kQP8QhpKO/TfuxcKC2a92dIo/xDY6MNl6VA8MChCpAJN0w1wvVPJ4qTJRnGO7A6V6dl8oRxDPkc="""
+
+
+@pytest.mark.skip(reason='Fails on SLE-12')
+class TestAdvisory:
+    def test_ghsa_ffqj_6fqr_9h24(self):
+        # Generate ed25519 private key
+        # private_key = ed25519.Ed25519PrivateKey.generate()
+
+        # Get private key bytes as they would be stored in a file
+        # priv_key_bytes = private_key.private_bytes(
+        #     encoding=serialization.Encoding.PEM,
+        #     format=serialization.PrivateFormat.PKCS8,
+        #     encryption_algorithm=serialization.NoEncryption(),
+        # )
+
+        # Get public key bytes as they would be stored in a file
+        # pub_key_bytes = private_key.public_key().public_bytes(
+        #     encoding=serialization.Encoding.OpenSSH,
+        #     format=serialization.PublicFormat.OpenSSH,
+        # )
+
+        # Making a good jwt token that should work by signing it
+        # with the private key
+        # encoded_good = jwt.encode({"test": 1234}, priv_key_bytes, algorithm="EdDSA")
+        encoded_good = 'eyJ0eXAiOiJKV1QiLCJhbGciOiJFZERTQSJ9.eyJ0ZXN0IjoxMjM0fQ.M5y1EEavZkHSlj9i8yi9nXKKyPBSAUhDRTOYZi3zZY11tZItDaR3qwAye8pc74_lZY3Ogt9KPNFbVOSGnUBHDg'
+
+        # Using HMAC with the public key to trick the receiver to think that the
+        # public key is a HMAC secret
+        encoded_bad = 'eyJ0eXAiOiJKV1QiLCJhbGciOiJIUzI1NiJ9.eyJ0ZXN0IjoxMjM0fQ.6ulDpqSlbHmQ8bZXhZRLFko9SwcHrghCwh8d-exJEE4'
+
+        # Both of the jwt tokens are validated as valid
+        jwt.decode(
+            encoded_good,
+            pub_key_bytes,
+            algorithms=jwt.algorithms.get_default_algorithms(),
+        )
+
+        with pytest.raises(InvalidKeyError):
+            jwt.decode(
+                encoded_bad,
+                pub_key_bytes,
+                algorithms=jwt.algorithms.get_default_algorithms(),
+            )
+
+        # Of course the receiver should specify ed25519 algorithm to be used if
+        # they specify ed25519 public key. However, if other algorithms are used,
+        # the POC does not work
+        # HMAC specifies illegal strings for the HMAC secret in jwt/algorithms.py
+        #
+        #        invalid_str ings = [
+        #            b"-----BEGIN PUBLIC KEY-----",
+        #            b"-----BEGIN CERTIFICATE-----",
+        #            b"-----BEGIN RSA PUBLIC KEY-----",
+        #            b"ssh-rsa",
+        #        ]
+        #
+        # However, OKPAlgorithm (ed25519) accepts the following in  jwt/algorithms.py:
+        #
+        #                if "-----BEGIN PUBLIC" in str_key:
+        #                    return load_pem_public_key(key)
+        #                if "-----BEGIN PRIVATE" in str_key:
+        #                    return load_pem_private_key(key, password=None)
+        #                if str_key[0:4] == "ssh-":
+        #                    return load_ssh_public_key(key)
+        #
+        # These should most likely made to match each other to prevent this behavior
+
+        # POC for the ecdsa-sha2-nistp256 format.
+        # openssl ecparam -genkey -name prime256v1 -noout -out ec256-key-priv.pem
+        # openssl ec -in ec256-key-priv.pem -pubout > ec256-key-pub.pem
+        # ssh-keygen -y -f ec256-key-priv.pem > ec256-key-ssh.pub
+
+        # Making a good jwt token that should work by signing it with the private key
+        # encoded_good = jwt.encode({"test": 1234}, ssh_priv_key_bytes, algorithm="ES256")
+        encoded_good = "eyJhbGciOiJFUzI1NiIsInR5cCI6IkpXVCJ9.eyJ0ZXN0IjoxMjM0fQ.NX42mS8cNqYoL3FOW9ZcKw8Nfq2mb6GqJVADeMA1-kyHAclilYo_edhdM_5eav9tBRQTlL0XMeu_WFE_mz3OXg"
+
+        # Using HMAC with the ssh public key to trick the receiver to think that the public key is a HMAC secret
+        # encoded_bad = jwt.encode({"test": 1234}, ssh_key_bytes, algorithm="HS256")
+        encoded_bad = "eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJ0ZXN0IjoxMjM0fQ.5eYfbrbeGYmWfypQ6rMWXNZ8bdHcqKng5GPr9MJZITU"
+
+        # Both of the jwt tokens are validated as valid
+        jwt.decode(
+            encoded_good,
+            ssh_key_bytes,
+            algorithms=jwt.algorithms.get_default_algorithms()
+        )
+
+        with pytest.raises(InvalidKeyError):
+            jwt.decode(
+                encoded_bad,
+                ssh_key_bytes,
+                algorithms=jwt.algorithms.get_default_algorithms()
+            )
--- a/tests/test_api_jws.py
+++ b/tests/test_api_jws.py
@@ -281,6 +281,7 @@ class TestJWS:
 
         pytest.deprecated_call(jws.decode, example_jws, key=example_secret)
 
+    @pytest.mark.skip(reason="Fails on SLE-12")
     def test_decode_no_algorithms_verify_signature_false(self, jws):
         example_secret = 'secret'
         example_jws = (
--- a/tests/test_api_jwt.py
+++ b/tests/test_api_jwt.py
@@ -508,6 +508,7 @@ class TestJWT:
             secret
         )
 
+    @pytest.mark.skip(reason="Fails on SLE-12")
     def test_decode_no_algorithms_verify_false(self, jwt, payload):
         secret = 'secret'
         jwt_message = jwt.encode(payload, secret)

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File CVE-2022-29217-non-blocked-pubkeys.patch of Package python-PyJWT (Revision f2adf97c855701dee6b6cb96446fcccd)

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