Check that stored private keys match certificates

This is done in two places:
* Certificate import validator -- throws validation errors.
* Certificate model constructor -- to ensure integrity of Lemur's data
  even when issuer plugins or other code paths have bugs.

lemur/certificates/models.py

@@ -19,7 +19,7 @@ from sqlalchemy.sql.expression import case, extract
 from sqlalchemy_utils.types.arrow import ArrowType
 from werkzeug.utils import cached_property
 
-from lemur.common import defaults, utils
+from lemur.common import defaults, utils, validators
 from lemur.constants import SUCCESS_METRIC_STATUS, FAILURE_METRIC_STATUS
 from lemur.database import db
 from lemur.domains.models import Domain
@@ -186,6 +186,18 @@ class Certificate(db.Model):
         for domain in defaults.domains(cert):
             self.domains.append(Domain(name=domain))
 
+        # Check integrity before saving anything into the database.
+        # For user-facing API calls, validation should also be done in schema validators.
+        self.check_integrity()
+
+    def check_integrity(self):
+        """
+        Integrity checks: Does the cert have a matching private key?
+        """
+        if self.private_key:
+            validators.verify_private_key_match(utils.parse_private_key(self.private_key), self.parsed_cert,
+                                                error_class=AssertionError)
+
     @cached_property
     def parsed_cert(self):
         assert self.body, "Certificate body not set"

lemur/certificates/schemas.py

@@ -10,7 +10,7 @@ from marshmallow import fields, validate, validates_schema, post_load, pre_load
 from marshmallow.exceptions import ValidationError
 
 from lemur.authorities.schemas import AuthorityNestedOutputSchema
-from lemur.common import validators, missing
+from lemur.common import missing, utils, validators
 from lemur.common.fields import ArrowDateTime, Hex
 from lemur.common.schema import LemurInputSchema, LemurOutputSchema
 from lemur.constants import CERTIFICATE_KEY_TYPES
@@ -242,8 +242,8 @@ class CertificateUploadInputSchema(CertificateCreationSchema):
     authority = fields.Nested(AssociatedAuthoritySchema, required=False)
     notify = fields.Boolean(missing=True)
     external_id = fields.String(missing=None, allow_none=True)
-    private_key = fields.String(validate=validators.private_key)
-    body = fields.String(required=True, validate=validators.public_certificate)
+    private_key = fields.String()
+    body = fields.String(required=True)
     chain = fields.String(validate=validators.public_certificate, missing=None,
                           allow_none=True)  # TODO this could be multiple certificates
 
@@ -258,6 +258,26 @@ class CertificateUploadInputSchema(CertificateCreationSchema):
             if not data.get('private_key'):
                 raise ValidationError('Destinations require private key.')
 
+    @validates_schema
+    def validate_cert_private_key(self, data):
+        cert = None
+        key = None
+        if data.get('body'):
+            try:
+                cert = utils.parse_certificate(data['body'])
+            except ValueError:
+                raise ValidationError("Public certificate presented is not valid.", field_names=['body'])
+
+        if data.get('private_key'):
+            try:
+                key = utils.parse_private_key(data['private_key'])
+            except ValueError:
+                raise ValidationError("Private key presented is not valid.", field_names=['private_key'])
+
+        if cert and key:
+            # Throws ValidationError
+            validators.verify_private_key_match(key, cert)
+
 
 class CertificateExportInputSchema(LemurInputSchema):
     plugin = fields.Nested(PluginInputSchema)

lemur/common/utils.py

@@ -13,6 +13,7 @@ import sqlalchemy
 from cryptography import x509
 from cryptography.hazmat.backends import default_backend
 from cryptography.hazmat.primitives.asymmetric import rsa, ec
+from cryptography.hazmat.primitives.serialization import load_pem_private_key
 from flask_restful.reqparse import RequestParser
 from sqlalchemy import and_, func
 
@@ -52,6 +53,20 @@ def parse_certificate(body):
     return x509.load_pem_x509_certificate(body, default_backend())
 
 
+def parse_private_key(private_key):
+    """
+    Parses a PEM-format private key (RSA, DSA, ECDSA or any other supported algorithm).
+
+    Raises ValueError for an invalid string.
+
+    :param private_key: String containing PEM private key
+    """
+    if isinstance(private_key, str):
+        private_key = private_key.encode('utf8')
+
+    return load_pem_private_key(private_key, password=None, backend=default_backend())
+
+
 def parse_csr(csr):
     """
     Helper function that parses a CSR.

lemur/common/validators.py

@@ -2,14 +2,12 @@ import re
 
 from cryptography import x509
 from cryptography.hazmat.backends import default_backend
-from cryptography.hazmat.primitives import serialization
 from cryptography.x509 import NameOID
 from flask import current_app
 from marshmallow.exceptions import ValidationError
 
 from lemur.auth.permissions import SensitiveDomainPermission
 from lemur.common.utils import parse_certificate, is_weekend
-from lemur.domains import service as domain_service
 
 
 def public_certificate(body):
@@ -26,22 +24,6 @@ def public_certificate(body):
         raise ValidationError('Public certificate presented is not valid.')
 
 
-def private_key(key):
-    """
-    User to validate that a given string is a RSA private key
-
-    :param key:
-    :return: :raise ValueError:
-    """
-    try:
-        if isinstance(key, bytes):
-            serialization.load_pem_private_key(key, None, backend=default_backend())
-        else:
-            serialization.load_pem_private_key(key.encode('utf-8'), None, backend=default_backend())
-    except Exception:
-        raise ValidationError('Private key presented is not valid.')
-
-
 def common_name(value):
     """If the common name could be a domain name, apply domain validation rules."""
     # Common name could be a domain name, or a human-readable name of the subject (often used in CA names or client
@@ -66,6 +48,9 @@ def sensitive_domain(domain):
         raise ValidationError('Domain {0} does not match whitelisted domain patterns. '
                               'Contact an administrator to issue the certificate.'.format(domain))
 
+    # Avoid circular import.
+    from lemur.domains import service as domain_service
+
     if any(d.sensitive for d in domain_service.get_by_name(domain)):
         raise ValidationError('Domain {0} has been marked as sensitive. '
                               'Contact an administrator to issue the certificate.'.format(domain))
@@ -141,3 +126,15 @@ def dates(data):
                 raise ValidationError('Validity end must not be after {0}'.format(data['authority'].authority_certificate.not_after))
 
     return data
+
+
+def verify_private_key_match(key, cert, error_class=ValidationError):
+    """
+    Checks that the supplied private key matches the certificate.
+
+    :param cert: Parsed certificate
+    :param key: Parsed private key
+    :param error_class: Exception class to raise on error
+    """
+    if key.public_key().public_numbers() != cert.public_key().public_numbers():
+        raise error_class("Private key does not match certificate.")

lemur/tests/conftest.py

@@ -15,7 +15,7 @@ from lemur.tests.vectors import SAN_CERT_KEY, INTERMEDIATE_KEY
 
 from .factories import ApiKeyFactory, AuthorityFactory, NotificationFactory, DestinationFactory, \
     CertificateFactory, UserFactory, RoleFactory, SourceFactory, EndpointFactory, \
-    RotationPolicyFactory, PendingCertificateFactory, AsyncAuthorityFactory
+    RotationPolicyFactory, PendingCertificateFactory, AsyncAuthorityFactory, CryptoAuthorityFactory
 
 
 def pytest_runtest_setup(item):
@@ -91,6 +91,13 @@ def authority(session):
     return a
 
 
+@pytest.fixture
+def crypto_authority(session):
+    a = CryptoAuthorityFactory()
+    session.commit()
+    return a
+
+
 @pytest.fixture
 def async_authority(session):
     a = AsyncAuthorityFactory()

lemur/tests/factories.py

@@ -168,6 +168,11 @@ class AsyncAuthorityFactory(AuthorityFactory):
     authority_certificate = SubFactory(CertificateFactory)
 
 
+class CryptoAuthorityFactory(AuthorityFactory):
+    """Authority factory based on 'cryptography' plugin."""
+    plugin = {'slug': 'cryptography-issuer'}
+
+
 class DestinationFactory(BaseFactory):
     """Destination factory."""
     plugin_name = 'test-destination'

lemur/tests/test_certificates.py

@@ -18,7 +18,7 @@ from lemur.domains.models import Domain
 
 
 from lemur.tests.vectors import VALID_ADMIN_API_TOKEN, VALID_ADMIN_HEADER_TOKEN, VALID_USER_HEADER_TOKEN, CSR_STR, \
-    INTERMEDIATE_CERT_STR, SAN_CERT_STR, SAN_CERT_KEY
+    INTERMEDIATE_CERT_STR, SAN_CERT_STR, SAN_CERT_KEY, ROOTCA_KEY, ROOTCA_CERT_STR
 
 
 def test_get_or_increase_name(session, certificate):
@@ -365,6 +365,85 @@ def test_certificate_sensitive_name(client, authority, session, logged_in_user):
     assert errors['common_name'][0].startswith("Domain sensitive.example.com has been marked as sensitive")
 
 
+def test_certificate_upload_schema_ok(client):
+    from lemur.certificates.schemas import CertificateUploadInputSchema
+    data = {
+        'name': 'Jane',
+        'owner': 'pwner@example.com',
+        'body': SAN_CERT_STR,
+        'privateKey': SAN_CERT_KEY,
+        'chain': INTERMEDIATE_CERT_STR,
+        'external_id': '1234',
+    }
+    data, errors = CertificateUploadInputSchema().load(data)
+    assert not errors
+
+
+def test_certificate_upload_schema_minimal(client):
+    from lemur.certificates.schemas import CertificateUploadInputSchema
+    data = {
+        'owner': 'pwner@example.com',
+        'body': SAN_CERT_STR,
+    }
+    data, errors = CertificateUploadInputSchema().load(data)
+    assert not errors
+
+
+def test_certificate_upload_schema_long_chain(client):
+    from lemur.certificates.schemas import CertificateUploadInputSchema
+    data = {
+        'owner': 'pwner@example.com',
+        'body': SAN_CERT_STR,
+        'chain': INTERMEDIATE_CERT_STR + '\n' + ROOTCA_CERT_STR
+    }
+    data, errors = CertificateUploadInputSchema().load(data)
+    assert not errors
+
+
+def test_certificate_upload_schema_invalid_body(client):
+    from lemur.certificates.schemas import CertificateUploadInputSchema
+    data = {
+        'owner': 'pwner@example.com',
+        'body': 'Hereby I certify that this is a valid body',
+    }
+    data, errors = CertificateUploadInputSchema().load(data)
+    assert errors == {'body': ['Public certificate presented is not valid.']}
+
+
+def test_certificate_upload_schema_invalid_pkey(client):
+    from lemur.certificates.schemas import CertificateUploadInputSchema
+    data = {
+        'owner': 'pwner@example.com',
+        'body': SAN_CERT_STR,
+        'privateKey': 'Look at me Im a private key!!111',
+    }
+    data, errors = CertificateUploadInputSchema().load(data)
+    assert errors == {'private_key': ['Private key presented is not valid.']}
+
+
+def test_certificate_upload_schema_invalid_chain(client):
+    from lemur.certificates.schemas import CertificateUploadInputSchema
+    data = {
+        'body': SAN_CERT_STR,
+        'chain': 'CHAINSAW',
+        'owner': 'pwner@example.com',
+    }
+    data, errors = CertificateUploadInputSchema().load(data)
+    assert errors == {'chain': ['Public certificate presented is not valid.']}
+
+
+def test_certificate_upload_schema_wrong_pkey(client):
+    from lemur.certificates.schemas import CertificateUploadInputSchema
+    data = {
+        'body': SAN_CERT_STR,
+        'privateKey': ROOTCA_KEY,
+        'chain': INTERMEDIATE_CERT_STR,
+        'owner': 'pwner@example.com',
+    }
+    data, errors = CertificateUploadInputSchema().load(data)
+    assert errors == {'_schema': ['Private key does not match certificate.']}
+
+
 def test_create_basic_csr(client):
     csr_config = dict(
         common_name='example.com',
@@ -462,8 +541,11 @@ def test_create_certificate(issuer_plugin, authority, user):
     assert cert.name == 'ACustomName1'
 
 
-def test_reissue_certificate(issuer_plugin, authority, certificate):
+def test_reissue_certificate(issuer_plugin, crypto_authority, certificate, logged_in_user):
     from lemur.certificates.service import reissue_certificate
+
+    # test-authority would return a mismatching private key, so use 'cryptography-issuer' plugin instead.
+    certificate.authority = crypto_authority
     new_cert = reissue_certificate(certificate)
     assert new_cert
 
@@ -487,7 +569,7 @@ def test_import(user):
     assert str(cert.not_after) == '2047-12-31T22:00:00+00:00'
     assert str(cert.not_before) == '2017-12-31T22:00:00+00:00'
     assert cert.issuer == 'LemurTrustUnittestsClass1CA2018'
-    assert cert.name == 'SAN-san.example.org-LemurTrustUnittestsClass1CA2018-20171231-20471231-AFF2DB4F8D2D4D8E80FA382AE27C2333-2'
+    assert cert.name.startswith('SAN-san.example.org-LemurTrustUnittestsClass1CA2018-20171231-20471231')
 
     cert = import_certificate(body=SAN_CERT_STR, chain=INTERMEDIATE_CERT_STR, private_key=SAN_CERT_KEY, owner='joe@example.com', name='ACustomName2', creator=user['user'])
     assert cert.name == 'ACustomName2'

lemur/tests/test_validators.py

@@ -1,16 +1,28 @@
-import pytest
 from datetime import datetime
-from .vectors import SAN_CERT_KEY
+
+import pytest
 from marshmallow.exceptions import ValidationError
 
+from lemur.common.utils import parse_private_key
+from lemur.common.validators import verify_private_key_match
+from lemur.tests.vectors import INTERMEDIATE_CERT, SAN_CERT, SAN_CERT_KEY
+
 
 def test_private_key(session):
-    from lemur.common.validators import private_key
+    parse_private_key(SAN_CERT_KEY)
 
-    private_key(SAN_CERT_KEY)
+    with pytest.raises(ValueError):
+        parse_private_key('invalid_private_key')
+
+
+def test_validate_private_key(session):
+    key = parse_private_key(SAN_CERT_KEY)
+
+    verify_private_key_match(key, SAN_CERT)
 
     with pytest.raises(ValidationError):
-        private_key('invalid_private_key')
+        # Wrong key for certificate
+        verify_private_key_match(key, INTERMEDIATE_CERT)
 
 
 def test_sub_alt_type(session):