openssl_csr: add support for name constraints extension (#92)

* Add support for name constraints extension to openssl_csr.

* Linting.

* Add tests.

* Fix IP address general name handling.

changelogs/fragments/92-ip-networks.yml

@@ -0,0 +1,2 @@
+bugfixes:
+- "openssl_*, x509_* modules - fix handling of general names which refer to IP networks and not IP addresses (https://github.com/ansible-collections/community.crypto/pull/92)."

changelogs/fragments/92-openssl_csr-name-constraints.yml

@@ -0,0 +1,3 @@
+minor_changes:
+- "openssl_csr - add support for name constraints extension (https://github.com/ansible-collections/community.crypto/issues/46)."
+- "openssl_csr_info - add support for name constraints extension (https://github.com/ansible-collections/community.crypto/issues/46)."

plugins/module_utils/crypto/cryptography_support.py

@@ -205,7 +205,10 @@ def cryptography_get_name(name):
         if name.startswith('DNS:'):
             return x509.DNSName(to_text(name[4:]))
         if name.startswith('IP:'):
-            return x509.IPAddress(ipaddress.ip_address(to_text(name[3:])))
+            address = to_text(name[3:])
+            if '/' in address:
+                return x509.IPAddress(ipaddress.ip_network(address))
+            return x509.IPAddress(ipaddress.ip_address(address))
         if name.startswith('email:'):
             return x509.RFC822Name(to_text(name[6:]))
         if name.startswith('URI:'):
@@ -261,6 +264,8 @@ def cryptography_decode_name(name):
     if isinstance(name, x509.DNSName):
         return 'DNS:{0}'.format(name.value)
     if isinstance(name, x509.IPAddress):
+        if isinstance(name.value, (ipaddress.IPv4Network, ipaddress.IPv6Network)):
+            return 'IP:{0}/{1}'.format(name.value.network_address.compressed, name.value.prefixlen)
         return 'IP:{0}'.format(name.value.compressed)
     if isinstance(name, x509.RFC822Name):
         return 'email:{0}'.format(name.value)

plugins/module_utils/crypto/pyopenssl_support.py

@@ -38,6 +38,10 @@
 
 from ._obj2txt import obj2txt
 
+from .basic import (
+    OpenSSLObjectError,
+)
+
 
 def pyopenssl_normalize_name(name, short=False):
     nid = OpenSSL._util.lib.OBJ_txt2nid(to_bytes(name))
@@ -56,9 +60,13 @@ def pyopenssl_normalize_name_attribute(san):
     if san.startswith('IP Address:'):
         san = 'IP:' + san[len('IP Address:'):]
     if san.startswith('IP:'):
-        ip = compat_ipaddress.ip_address(san[3:])
-        san = 'IP:{0}'.format(ip.compressed)
-
+        address = san[3:]
+        if '/' in address:
+            ip = compat_ipaddress.ip_network(address)
+            san = 'IP:{0}/{1}'.format(ip.network_address.compressed, ip.prefixlen)
+        else:
+            ip = compat_ipaddress.ip_address(address)
+            san = 'IP:{0}'.format(ip.compressed)
     if san.startswith('Registered ID:'):
         san = 'RID:' + san[len('Registered ID:'):]
     # Some versions of OpenSSL apparently forgot the colon. Happens in CI with Ubuntu 16.04 and FreeBSD 11.1
@@ -119,3 +127,28 @@ def pyopenssl_get_extensions_from_csr(csr):
         # similarly to how cryptography does it.
         result[oid] = entry
     return result
+
+
+def pyopenssl_parse_name_constraints(name_constraints_extension):
+    lines = to_text(name_constraints_extension, errors='surrogate_or_strict').splitlines()
+    exclude = None
+    excluded = []
+    permitted = []
+    for line in lines:
+        if line.startswith(' ') or line.startswith('\t'):
+            name = pyopenssl_normalize_name_attribute(line.strip())
+            if exclude is True:
+                excluded.append(name)
+            elif exclude is False:
+                permitted.append(name)
+            else:
+                raise OpenSSLObjectError('Unexpected nameConstraint line: "{0}"'.format(line))
+        else:
+            line_lc = line.lower()
+            if line_lc.startswith('exclud'):
+                exclude = True
+            elif line_lc.startswith('includ') or line_lc.startswith('permitt'):
+                exclude = False
+            else:
+                raise OpenSSLObjectError('Cannot parse nameConstraint line: "{0}"'.format(line))
+    return permitted, excluded

plugins/modules/openssl_csr.py

@@ -183,13 +183,36 @@
         aliases: [ ocspMustStaple ]
     ocsp_must_staple_critical:
         description:
-            - Should the OCSP Must Staple extension be considered as critical
+            - Should the OCSP Must Staple extension be considered as critical.
             - Note that according to the RFC, this extension should not be marked
               as critical, as old clients not knowing about OCSP Must Staple
               are required to reject such certificates
               (see U(https://tools.ietf.org/html/rfc7633#section-4)).
         type: bool
         aliases: [ ocspMustStaple_critical ]
+    name_constraints_permitted:
+        description:
+            - For CA certificates, this specifies a list of identifiers which describe
+              subtrees of names that this CA is allowed to issue certificates for.
+            - Values must be prefixed by their options. (i.e., C(email), C(URI), C(DNS), C(RID), C(IP), C(dirName),
+              C(otherName) and the ones specific to your CA).
+        type: list
+        elements: str
+        version_added: 1.1.0
+    name_constraints_excluded:
+        description:
+            - For CA certificates, this specifies a list of identifiers which describe
+              subtrees of names that this CA is *not* allowed to issue certificates for.
+            - Values must be prefixed by their options. (i.e., C(email), C(URI), C(DNS), C(RID), C(IP), C(dirName),
+              C(otherName) and the ones specific to your CA).
+        type: list
+        elements: str
+        version_added: 1.1.0
+    name_constraints_critical:
+        description:
+            - Should the Name Constraints extension be considered as critical.
+        type: bool
+        version_added: 1.1.0
     select_crypto_backend:
         description:
             - Determines which crypto backend to use.
@@ -412,6 +435,20 @@
     returned: changed or success
     type: bool
     sample: false
+name_constraints_permitted:
+    description: List of permitted subtrees to sign certificates for.
+    returned: changed or success
+    type: list
+    elements: str
+    sample: ['email:.somedomain.com']
+    version_added: 1.1.0
+name_constraints_excluded:
+    description: List of excluded subtrees the CA cannot sign certificates for.
+    returned: changed or success
+    type: list
+    elements: str
+    sample: ['email:.com']
+    version_added: 1.1.0
 backup_file:
     description: Name of backup file created.
     returned: changed and if I(backup) is C(yes)
@@ -461,6 +498,7 @@
 
 from ansible_collections.community.crypto.plugins.module_utils.crypto.pyopenssl_support import (
     pyopenssl_normalize_name_attribute,
+    pyopenssl_parse_name_constraints,
 )
 
 MINIMAL_PYOPENSSL_VERSION = '0.15'
@@ -534,6 +572,9 @@ def __init__(self, module):
         self.basicConstraints_critical = module.params['basic_constraints_critical']
         self.ocspMustStaple = module.params['ocsp_must_staple']
         self.ocspMustStaple_critical = module.params['ocsp_must_staple_critical']
+        self.name_constraints_permitted = module.params['name_constraints_permitted'] or []
+        self.name_constraints_excluded = module.params['name_constraints_excluded'] or []
+        self.name_constraints_critical = module.params['name_constraints_critical']
         self.create_subject_key_identifier = module.params['create_subject_key_identifier']
         self.subject_key_identifier = module.params['subject_key_identifier']
         self.authority_key_identifier = module.params['authority_key_identifier']
@@ -637,7 +678,9 @@ def dump(self):
             'extendedKeyUsage': self.extendedKeyUsage,
             'basicConstraints': self.basicConstraints,
             'ocspMustStaple': self.ocspMustStaple,
-            'changed': self.changed
+            'changed': self.changed,
+            'name_constraints_permitted': self.name_constraints_permitted,
+            'name_constraints_excluded': self.name_constraints_excluded,
         }
         if self.backup_file:
             result['backup_file'] = self.backup_file
@@ -697,6 +740,13 @@ def _generate_csr(self):
             usages = ', '.join(self.basicConstraints)
             extensions.append(crypto.X509Extension(b"basicConstraints", self.basicConstraints_critical, usages.encode('ascii')))
 
+        if self.name_constraints_permitted or self.name_constraints_excluded:
+            usages = ', '.join(
+                ['permitted;{0}'.format(name) for name in self.name_constraints_permitted] +
+                ['excluded;{0}'.format(name) for name in self.name_constraints_excluded]
+            )
+            extensions.append(crypto.X509Extension(b"nameConstraints", self.name_constraints_critical, usages.encode('ascii')))
+
         if self.ocspMustStaple:
             extensions.append(crypto.X509Extension(OPENSSL_MUST_STAPLE_NAME, self.ocspMustStaple_critical, OPENSSL_MUST_STAPLE_VALUE))
 
@@ -773,6 +823,22 @@ def _check_extenededKeyUsage(extensions):
         def _check_basicConstraints(extensions):
             return _check_keyUsage_(extensions, b'basicConstraints', self.basicConstraints, self.basicConstraints_critical)
 
+        def _check_nameConstraints(extensions):
+            nc_ext = next((ext for ext in extensions if ext.get_short_name() == b'nameConstraints'), '')
+            permitted, excluded = pyopenssl_parse_name_constraints(nc_ext)
+            if self.name_constraints_permitted or self.name_constraints_excluded:
+                if set(permitted) != set([pyopenssl_normalize_name_attribute(to_text(name)) for name in self.name_constraints_permitted]):
+                    return False
+                if set(excluded) != set([pyopenssl_normalize_name_attribute(to_text(name)) for name in self.name_constraints_excluded]):
+                    return False
+                if nc_ext.get_critical() != self.name_constraints_critical:
+                    return False
+            else:
+                if permitted or excluded:
+                    return False
+
+            return True
+
         def _check_ocspMustStaple(extensions):
             oms_ext = [ext for ext in extensions if to_bytes(ext.get_short_name()) == OPENSSL_MUST_STAPLE_NAME and to_bytes(ext) == OPENSSL_MUST_STAPLE_VALUE]
             if OpenSSL.SSL.OPENSSL_VERSION_NUMBER < 0x10100000:
@@ -787,7 +853,7 @@ def _check_extensions(csr):
             extensions = csr.get_extensions()
             return (_check_subjectAltName(extensions) and _check_keyUsage(extensions) and
                     _check_extenededKeyUsage(extensions) and _check_basicConstraints(extensions) and
-                    _check_ocspMustStaple(extensions))
+                    _check_ocspMustStaple(extensions) and _check_nameConstraints(extensions))
 
         def _check_signature(csr):
             try:
@@ -849,6 +915,15 @@ def _generate_csr(self):
                     critical=self.ocspMustStaple_critical
                 )
 
+        if self.name_constraints_permitted or self.name_constraints_excluded:
+            try:
+                csr = csr.add_extension(cryptography.x509.NameConstraints(
+                    [cryptography_get_name(name) for name in self.name_constraints_permitted],
+                    [cryptography_get_name(name) for name in self.name_constraints_excluded],
+                ), critical=self.name_constraints_critical)
+            except TypeError as e:
+                raise OpenSSLObjectError('Error while parsing name constraint: {0}'.format(e))
+
         if self.create_subject_key_identifier:
             csr = csr.add_extension(
                 cryptography.x509.SubjectKeyIdentifier.from_public_key(self.privatekey.public_key()),
@@ -991,6 +1066,19 @@ def _check_ocspMustStaple(extensions):
             else:
                 return tlsfeature_ext is None
 
+        def _check_nameConstraints(extensions):
+            current_nc_ext = _find_extension(extensions, cryptography.x509.NameConstraints)
+            current_nc_perm = [str(altname) for altname in current_nc_ext.value.permitted_subtrees] if current_nc_ext else []
+            current_nc_excl = [str(altname) for altname in current_nc_ext.value.excluded_subtrees] if current_nc_ext else []
+            nc_perm = [str(cryptography_get_name(altname)) for altname in self.name_constraints_permitted]
+            nc_excl = [str(cryptography_get_name(altname)) for altname in self.name_constraints_excluded]
+            if set(nc_perm) != set(current_nc_perm) or set(nc_excl) != set(current_nc_excl):
+                return False
+            if nc_perm or nc_excl:
+                if current_nc_ext.critical != self.name_constraints_critical:
+                    return False
+            return True
+
         def _check_subject_key_identifier(extensions):
             ext = _find_extension(extensions, cryptography.x509.SubjectKeyIdentifier)
             if self.create_subject_key_identifier or self.subject_key_identifier is not None:
@@ -1026,7 +1114,7 @@ def _check_extensions(csr):
             return (_check_subjectAltName(extensions) and _check_keyUsage(extensions) and
                     _check_extenededKeyUsage(extensions) and _check_basicConstraints(extensions) and
                     _check_ocspMustStaple(extensions) and _check_subject_key_identifier(extensions) and
-                    _check_authority_key_identifier(extensions))
+                    _check_authority_key_identifier(extensions) and _check_nameConstraints(extensions))
 
         def _check_signature(csr):
             if not csr.is_signature_valid:
@@ -1081,6 +1169,9 @@ def main():
             basic_constraints_critical=dict(type='bool', default=False, aliases=['basicConstraints_critical']),
             ocsp_must_staple=dict(type='bool', default=False, aliases=['ocspMustStaple']),
             ocsp_must_staple_critical=dict(type='bool', default=False, aliases=['ocspMustStaple_critical']),
+            name_constraints_permitted=dict(type='list', elements='str'),
+            name_constraints_excluded=dict(type='list', elements='str'),
+            name_constraints_critical=dict(type='bool', default=False),
             backup=dict(type='bool', default=False),
             create_subject_key_identifier=dict(type='bool', default=False),
             subject_key_identifier=dict(type='str'),

plugins/modules/openssl_csr_info.py

@@ -141,6 +141,29 @@
     description: Whether the C(ocsp_must_staple) extension is critical.
     returned: success
     type: bool
+name_constraints_permitted:
+    description: List of permitted subtrees to sign certificates for.
+    returned: success
+    type: list
+    elements: str
+    sample: ['email:.somedomain.com']
+    version_added: 1.1.0
+name_constraints_excluded:
+    description:
+        - List of excluded subtrees the CA cannot sign certificates for.
+        - Is C(none) if extension is not present.
+    returned: success
+    type: list
+    elements: str
+    sample: ['email:.com']
+    version_added: 1.1.0
+name_constraints_critical:
+    description:
+        - Whether the C(name_constraints) extension is critical.
+        - Is C(none) if extension is not present.
+    returned: success
+    type: bool
+    version_added: 1.1.0
 subject:
     description:
         - The CSR's subject as a dictionary.
@@ -231,6 +254,7 @@
     pyopenssl_get_extensions_from_csr,
     pyopenssl_normalize_name,
     pyopenssl_normalize_name_attribute,
+    pyopenssl_parse_name_constraints,
 )
 
 MINIMAL_CRYPTOGRAPHY_VERSION = '1.3'
@@ -317,6 +341,10 @@ def _get_ocsp_must_staple(self):
     def _get_subject_alt_name(self):
         pass
 
+    @abc.abstractmethod
+    def _get_name_constraints(self):
+        pass
+
     @abc.abstractmethod
     def _get_public_key(self, binary):
         pass
@@ -351,6 +379,11 @@ def get_info(self):
         result['basic_constraints'], result['basic_constraints_critical'] = self._get_basic_constraints()
         result['ocsp_must_staple'], result['ocsp_must_staple_critical'] = self._get_ocsp_must_staple()
         result['subject_alt_name'], result['subject_alt_name_critical'] = self._get_subject_alt_name()
+        (
+            result['name_constraints_permitted'],
+            result['name_constraints_excluded'],
+            result['name_constraints_critical'],
+        ) = self._get_name_constraints()
 
         result['public_key'] = self._get_public_key(binary=False)
         pk = self._get_public_key(binary=True)
@@ -474,6 +507,15 @@ def _get_subject_alt_name(self):
         except cryptography.x509.ExtensionNotFound:
             return None, False
 
+    def _get_name_constraints(self):
+        try:
+            nc_ext = self.csr.extensions.get_extension_for_class(x509.NameConstraints)
+            permitted = [cryptography_decode_name(san) for san in nc_ext.value.permitted_subtrees or []]
+            excluded = [cryptography_decode_name(san) for san in nc_ext.value.excluded_subtrees or []]
+            return permitted, excluded, nc_ext.critical
+        except cryptography.x509.ExtensionNotFound:
+            return None, None, False
+
     def _get_public_key(self, binary):
         return self.csr.public_key().public_bytes(
             serialization.Encoding.DER if binary else serialization.Encoding.PEM,
@@ -559,6 +601,13 @@ def _get_subject_alt_name(self):
                 return result, bool(extension.get_critical())
         return None, False
 
+    def _get_name_constraints(self):
+        for extension in self.csr.get_extensions():
+            if extension.get_short_name() == b'nameConstraints':
+                permitted, excluded = pyopenssl_parse_name_constraints(extension)
+                return permitted, excluded, bool(extension.get_critical())
+        return None, None, False
+
     def _get_public_key(self, binary):
         try:
             return crypto.dump_publickey(