# Authors: Rob Crittenden # # Copyright (C) 2009 Red Hat # see file 'COPYING' for use and warranty information # # This program is free software; you can redistribute it and/or modify # it under the terms of the GNU General Public License as published by # the Free Software Foundation, either version 3 of the License, or # (at your option) any later version. # # This program is distributed in the hope that it will be useful, # but WITHOUT ANY WARRANTY; without even the implied warranty of # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the # GNU General Public License for more details. # # You should have received a copy of the GNU General Public License # along with this program. If not, see . # import collections import os import io import pwd import grp import re import tempfile from tempfile import NamedTemporaryFile import shutil import base64 from cryptography.hazmat.primitives import serialization import cryptography.x509 from ipapython.dn import DN from ipapython.ipa_log_manager import root_logger from ipapython.kerberos import Principal from ipapython import ipautil from ipalib import x509 # pylint: disable=ipa-forbidden-import try: # pylint: disable=import-error,ipa-forbidden-import from ipaplatform.paths import paths # pylint: enable=import-error,ipa-forbidden-import except ImportError: CERTUTIL = '/usr/bin/certutil' PK12UTIL = '/usr/bin/pk12util' OPENSSL = '/usr/bin/openssl' else: CERTUTIL = paths.CERTUTIL PK12UTIL = paths.PK12UTIL OPENSSL = paths.OPENSSL CA_NICKNAME_FMT = "%s IPA CA" NSS_FILES = ("cert8.db", "key3.db", "secmod.db", "pwdfile.txt") BAD_USAGE_ERR = 'Certificate key usage inadequate for attempted operation.' TrustFlags = collections.namedtuple('TrustFlags', 'has_key trusted ca usages') EMPTY_TRUST_FLAGS = TrustFlags(False, None, None, None) IPA_CA_TRUST_FLAGS = TrustFlags( False, True, True, frozenset({ x509.EKU_SERVER_AUTH, x509.EKU_CLIENT_AUTH, x509.EKU_CODE_SIGNING, x509.EKU_EMAIL_PROTECTION, x509.EKU_PKINIT_CLIENT_AUTH, x509.EKU_PKINIT_KDC, }), ) EXTERNAL_CA_TRUST_FLAGS = TrustFlags( False, True, True, frozenset({x509.EKU_SERVER_AUTH}), ) TRUSTED_PEER_TRUST_FLAGS = TrustFlags( False, True, False, frozenset({x509.EKU_SERVER_AUTH}), ) def get_ca_nickname(realm, format=CA_NICKNAME_FMT): return format % realm def find_cert_from_txt(cert, start=0): """ Given a cert blob (str) which may or may not contian leading and trailing text, pull out just the certificate part. This will return the FIRST cert in a stream of data. Returns a tuple (certificate, last position in cert) """ s = cert.find('-----BEGIN CERTIFICATE-----', start) e = cert.find('-----END CERTIFICATE-----', s) if e > 0: e = e + 25 if s < 0 or e < 0: raise RuntimeError("Unable to find certificate") cert = cert[s:e] return (cert, e) def parse_trust_flags(trust_flags): """ Convert certutil trust flags to TrustFlags object. """ has_key = 'u' in trust_flags if 'p' in trust_flags: if 'C' in trust_flags or 'P' in trust_flags or 'T' in trust_flags: raise ValueError("cannot be both trusted and not trusted") return False, None, None elif 'C' in trust_flags or 'T' in trust_flags: if 'P' in trust_flags: raise ValueError("cannot be both CA and not CA") ca = True elif 'P' in trust_flags: ca = False else: return TrustFlags(has_key, None, None, frozenset()) trust_flags = trust_flags.split(',') ext_key_usage = set() for i, kp in enumerate((x509.EKU_SERVER_AUTH, x509.EKU_EMAIL_PROTECTION, x509.EKU_CODE_SIGNING)): if 'C' in trust_flags[i] or 'P' in trust_flags[i]: ext_key_usage.add(kp) if 'T' in trust_flags[0]: ext_key_usage.add(x509.EKU_CLIENT_AUTH) return TrustFlags(has_key, True, ca, frozenset(ext_key_usage)) def unparse_trust_flags(trust_flags): """ Convert TrustFlags object to certutil trust flags. """ has_key, trusted, ca, ext_key_usage = trust_flags if trusted is False: if has_key: return 'pu,pu,pu' else: return 'p,p,p' elif trusted is None or ca is None: if has_key: return 'u,u,u' else: return ',,' elif ext_key_usage is None: if ca: if has_key: return 'CTu,Cu,Cu' else: return 'CT,C,C' else: if has_key: return 'Pu,Pu,Pu' else: return 'P,P,P' trust_flags = ['', '', ''] for i, kp in enumerate((x509.EKU_SERVER_AUTH, x509.EKU_EMAIL_PROTECTION, x509.EKU_CODE_SIGNING)): if kp in ext_key_usage: trust_flags[i] += ('C' if ca else 'P') if ca and x509.EKU_CLIENT_AUTH in ext_key_usage: trust_flags[0] += 'T' if has_key: for i in range(3): trust_flags[i] += 'u' trust_flags = ','.join(trust_flags) return trust_flags def verify_kdc_cert_validity(kdc_cert, ca_certs, realm): pem_kdc_cert = kdc_cert.public_bytes(serialization.Encoding.PEM) pem_ca_certs = '\n'.join( cert.public_bytes(serialization.Encoding.PEM) for cert in ca_certs) with NamedTemporaryFile() as kdc_file, NamedTemporaryFile() as ca_file: kdc_file.write(pem_kdc_cert) kdc_file.flush() ca_file.write(pem_ca_certs) ca_file.flush() try: ipautil.run( [OPENSSL, 'verify', '-CAfile', ca_file.name, kdc_file.name]) eku = kdc_cert.extensions.get_extension_for_class( cryptography.x509.ExtendedKeyUsage) list(eku.value).index( cryptography.x509.ObjectIdentifier(x509.EKU_PKINIT_KDC)) except (ipautil.CalledProcessError, cryptography.x509.ExtensionNotFound, ValueError): raise ValueError("invalid for a KDC") principal = str(Principal(['krbtgt', realm], realm)) gns = x509.process_othernames(x509.get_san_general_names(kdc_cert)) for gn in gns: if isinstance(gn, x509.KRB5PrincipalName) and gn.name == principal: break else: raise ValueError("invalid for realm %s" % realm) class NSSDatabase(object): """A general-purpose wrapper around a NSS cert database For permanent NSS databases, pass the cert DB directory to __init__ For temporary databases, do not pass nssdir, and call close() when done to remove the DB. Alternatively, a NSSDatabase can be used as a context manager that calls close() automatically. """ # Traditionally, we used CertDB for our NSS DB operations, but that class # got too tied to IPA server details, killing reusability. # BaseCertDB is a class that knows nothing about IPA. # Generic NSS DB code should be moved here. def __init__(self, nssdir=None): if nssdir is None: self.secdir = tempfile.mkdtemp() self._is_temporary = True else: self.secdir = nssdir self._is_temporary = False self.pwd_file = os.path.join(self.secdir, 'pwdfile.txt') def close(self): if self._is_temporary: shutil.rmtree(self.secdir) def __enter__(self): return self def __exit__(self, type, value, tb): self.close() def run_certutil(self, args, stdin=None, **kwargs): new_args = [CERTUTIL, "-d", self.secdir] new_args = new_args + args new_args.extend(['-f', self.pwd_file]) return ipautil.run(new_args, stdin, **kwargs) def create_db(self, user=None, group=None, mode=None, backup=False): """Create cert DB :param user: User owner the secdir :param group: Group owner of the secdir :param mode: Mode of the secdir :param backup: Backup the sedir files """ dirmode = 0o750 filemode = 0o640 pwdfilemode = 0o640 if mode is not None: dirmode = mode filemode = mode & 0o666 pwdfilemode = mode & 0o660 uid = -1 gid = -1 if user is not None: uid = pwd.getpwnam(user).pw_uid if group is not None: gid = grp.getgrnam(group).gr_gid if backup: for filename in NSS_FILES: path = os.path.join(self.secdir, filename) ipautil.backup_file(path) if not os.path.exists(self.secdir): os.makedirs(self.secdir, dirmode) if not os.path.exists(self.pwd_file): # Create the password file for this db with io.open(os.open(self.pwd_file, os.O_CREAT | os.O_WRONLY, pwdfilemode), 'w', closefd=True) as f: f.write(ipautil.ipa_generate_password()) f.flush() self.run_certutil(["-N", "-f", self.pwd_file]) # Finally fix up perms os.chown(self.secdir, uid, gid) os.chmod(self.secdir, dirmode) for filename in NSS_FILES: path = os.path.join(self.secdir, filename) if os.path.exists(path): os.chown(path, uid, gid) if path == self.pwd_file: new_mode = pwdfilemode else: new_mode = filemode os.chmod(path, new_mode) def restore(self): for filename in NSS_FILES: path = os.path.join(self.secdir, filename) backup_path = path + '.orig' save_path = path + '.ipasave' try: if os.path.exists(path): os.rename(path, save_path) if os.path.exists(backup_path): os.rename(backup_path, path) except OSError as e: root_logger.debug(e) def list_certs(self): """Return nicknames and cert flags for all certs in the database :return: List of (name, trust_flags) tuples """ result = self.run_certutil(["-L"], capture_output=True) certs = result.output.splitlines() # FIXME, this relies on NSS never changing the formatting of certutil certlist = [] for cert in certs: match = re.match(r'^(.+?)\s+(\w*,\w*,\w*)\s*$', cert) if match: nickname = match.group(1) trust_flags = parse_trust_flags(match.group(2)) certlist.append((nickname, trust_flags)) return tuple(certlist) def find_server_certs(self): """Return nicknames and cert flags for server certs in the database Server certs have an "u" character in the trust flags. :return: List of (name, trust_flags) tuples """ server_certs = [] for name, flags in self.list_certs(): if flags.has_key: server_certs.append((name, flags)) return server_certs def get_trust_chain(self, nickname): """Return names of certs in a given cert's trust chain :param nickname: Name of the cert :return: List of certificate names """ root_nicknames = [] result = self.run_certutil(["-O", "-n", nickname], capture_output=True) chain = result.output.splitlines() for c in chain: m = re.match('\s*"(.*)" \[.*', c) if m: root_nicknames.append(m.groups()[0]) return root_nicknames def export_pkcs12(self, nickname, pkcs12_filename, pkcs12_passwd=None): args = [PK12UTIL, "-d", self.secdir, "-o", pkcs12_filename, "-n", nickname, "-k", self.pwd_file] pkcs12_password_file = None if pkcs12_passwd is not None: pkcs12_password_file = ipautil.write_tmp_file(pkcs12_passwd + '\n') args = args + ["-w", pkcs12_password_file.name] try: ipautil.run(args) except ipautil.CalledProcessError as e: if e.returncode == 17: raise RuntimeError("incorrect password for pkcs#12 file %s" % pkcs12_filename) elif e.returncode == 10: raise RuntimeError("Failed to open %s" % pkcs12_filename) else: raise RuntimeError("unknown error exporting pkcs#12 file %s" % pkcs12_filename) finally: if pkcs12_password_file is not None: pkcs12_password_file.close() def import_pkcs12(self, pkcs12_filename, pkcs12_passwd=None): args = [PK12UTIL, "-d", self.secdir, "-i", pkcs12_filename, "-k", self.pwd_file, '-v'] pkcs12_password_file = None if pkcs12_passwd is not None: pkcs12_password_file = ipautil.write_tmp_file(pkcs12_passwd + '\n') args = args + ["-w", pkcs12_password_file.name] try: ipautil.run(args) except ipautil.CalledProcessError as e: if e.returncode == 17: raise RuntimeError("incorrect password for pkcs#12 file %s" % pkcs12_filename) elif e.returncode == 10: raise RuntimeError("Failed to open %s" % pkcs12_filename) else: raise RuntimeError("unknown error import pkcs#12 file %s" % pkcs12_filename) finally: if pkcs12_password_file is not None: pkcs12_password_file.close() def import_files(self, files, import_keys=False, key_password=None, key_nickname=None): """ Import certificates and a single private key from multiple files The files may be in PEM and DER certificate, PKCS#7 certificate chain, PKCS#8 and raw private key and PKCS#12 formats. :param files: Names of files to import :param import_keys: Whether to import private keys :param key_password: Password to decrypt private keys :param key_nickname: Nickname of the private key to import from PKCS#12 files """ key_file = None extracted_key = None extracted_certs = [] for filename in files: try: with open(filename, 'rb') as f: data = f.read() except IOError as e: raise RuntimeError( "Failed to open %s: %s" % (filename, e.strerror)) # Try to parse the file as PEM file matches = list(re.finditer( r'-----BEGIN (.+?)-----(.*?)-----END \1-----', data, re.DOTALL)) if matches: loaded = False for match in matches: body = match.group() label = match.group(1) line = len(data[:match.start() + 1].splitlines()) if label in ('CERTIFICATE', 'X509 CERTIFICATE', 'X.509 CERTIFICATE'): try: x509.load_certificate(match.group(2)) except ValueError as e: if label != 'CERTIFICATE': root_logger.warning( "Skipping certificate in %s at line %s: %s", filename, line, e) continue else: extracted_certs.append(body) loaded = True continue if label in ('PKCS7', 'PKCS #7 SIGNED DATA', 'CERTIFICATE'): try: certs = x509.pkcs7_to_pems(body) except ipautil.CalledProcessError as e: if label == 'CERTIFICATE': root_logger.warning( "Skipping certificate in %s at line %s: %s", filename, line, e) else: root_logger.warning( "Skipping PKCS#7 in %s at line %s: %s", filename, line, e) continue else: extracted_certs.extend(certs) loaded = True continue if label in ('PRIVATE KEY', 'ENCRYPTED PRIVATE KEY', 'RSA PRIVATE KEY', 'DSA PRIVATE KEY', 'EC PRIVATE KEY'): if not import_keys: continue if key_file: raise RuntimeError( "Can't load private key from both %s and %s" % (key_file, filename)) args = [ OPENSSL, 'pkcs8', '-topk8', '-passout', 'file:' + self.pwd_file, ] if ((label != 'PRIVATE KEY' and key_password) or label == 'ENCRYPTED PRIVATE KEY'): key_pwdfile = ipautil.write_tmp_file(key_password) args += [ '-passin', 'file:' + key_pwdfile.name, ] try: result = ipautil.run( args, stdin=body, capture_output=True) except ipautil.CalledProcessError as e: root_logger.warning( "Skipping private key in %s at line %s: %s", filename, line, e) continue else: extracted_key = result.output key_file = filename loaded = True continue if loaded: continue raise RuntimeError("Failed to load %s" % filename) # Try to load the file as DER certificate try: x509.load_certificate(data, x509.DER) except ValueError: pass else: data = x509.make_pem(base64.b64encode(data)) extracted_certs.append(data) continue # Try to import the file as PKCS#12 file if import_keys: try: self.import_pkcs12(filename, key_password) except RuntimeError: pass else: if key_file: raise RuntimeError( "Can't load private key from both %s and %s" % (key_file, filename)) key_file = filename server_certs = self.find_server_certs() if key_nickname: for nickname, _trust_flags in server_certs: if nickname == key_nickname: break else: raise RuntimeError( "Server certificate \"%s\" not found in %s" % (key_nickname, filename)) else: if len(server_certs) > 1: raise RuntimeError( "%s server certificates found in %s, " "expecting only one" % (len(server_certs), filename)) continue raise RuntimeError("Failed to load %s" % filename) if import_keys and not key_file: raise RuntimeError( "No server certificates found in %s" % (', '.join(files))) for cert_pem in extracted_certs: cert = x509.load_certificate(cert_pem) nickname = str(DN(cert.subject)) data = cert.public_bytes(serialization.Encoding.DER) self.add_cert(data, nickname, EMPTY_TRUST_FLAGS) if extracted_key: in_file = ipautil.write_tmp_file( '\n'.join(extracted_certs) + '\n' + extracted_key) out_file = tempfile.NamedTemporaryFile() out_password = ipautil.ipa_generate_password() out_pwdfile = ipautil.write_tmp_file(out_password) args = [ OPENSSL, 'pkcs12', '-export', '-in', in_file.name, '-out', out_file.name, '-passin', 'file:' + self.pwd_file, '-passout', 'file:' + out_pwdfile.name, ] try: ipautil.run(args) except ipautil.CalledProcessError as e: raise RuntimeError( "No matching certificate found for private key from %s" % key_file) self.import_pkcs12(out_file.name, out_password) def trust_root_cert(self, root_nickname, trust_flags): if root_nickname[:7] == "Builtin": root_logger.debug( "No need to add trust for built-in root CAs, skipping %s" % root_nickname) else: trust_flags = unparse_trust_flags(trust_flags) try: self.run_certutil(["-M", "-n", root_nickname, "-t", trust_flags]) except ipautil.CalledProcessError: raise RuntimeError( "Setting trust on %s failed" % root_nickname) def get_cert(self, nickname, pem=False): args = ['-L', '-n', nickname, '-a'] try: result = self.run_certutil(args, capture_output=True) except ipautil.CalledProcessError: raise RuntimeError("Failed to get %s" % nickname) cert = result.output if not pem: cert, _start = find_cert_from_txt(cert, start=0) cert = x509.strip_header(cert) cert = base64.b64decode(cert) return cert def has_nickname(self, nickname): try: self.get_cert(nickname) except RuntimeError: # This might be error other than "nickname not found". Beware. return False else: return True def export_pem_cert(self, nickname, location): """Export the given cert to PEM file in the given location""" cert = self.get_cert(nickname, pem=True) with open(location, "w+") as fd: fd.write(cert) os.chmod(location, 0o444) def import_pem_cert(self, nickname, flags, location): """Import a cert form the given PEM file. The file must contain exactly one certificate. """ try: with open(location) as fd: certs = fd.read() except IOError as e: raise RuntimeError( "Failed to open %s: %s" % (location, e.strerror) ) cert, st = find_cert_from_txt(certs) self.add_cert(cert, nickname, flags, pem=True) try: find_cert_from_txt(certs, st) except RuntimeError: pass else: raise ValueError('%s contains more than one certificate' % location) def add_cert(self, cert, nick, flags, pem=False): flags = unparse_trust_flags(flags) args = ["-A", "-n", nick, "-t", flags] if pem: args.append("-a") self.run_certutil(args, stdin=cert) def delete_cert(self, nick): self.run_certutil(["-D", "-n", nick]) def verify_server_cert_validity(self, nickname, hostname): """Verify a certificate is valid for a SSL server with given hostname Raises a ValueError if the certificate is invalid. """ cert = self.get_cert(nickname) cert = x509.load_certificate(cert, x509.DER) try: self.run_certutil(['-V', '-n', nickname, '-u', 'V'], capture_output=True) except ipautil.CalledProcessError as e: # certutil output in case of error is # 'certutil: certificate is invalid: \n' msg = e.output.split(': ')[2].strip() if msg == BAD_USAGE_ERR: msg = 'invalid for a SSL server.' raise ValueError(msg) try: x509.match_hostname(cert, hostname) except ValueError: raise ValueError('invalid for server %s' % hostname) def verify_ca_cert_validity(self, nickname): cert = self.get_cert(nickname) cert = x509.load_certificate(cert, x509.DER) if not cert.subject: raise ValueError("has empty subject") try: bc = cert.extensions.get_extension_for_class( cryptography.x509.BasicConstraints) except cryptography.x509.ExtensionNotFound: raise ValueError("missing basic constraints") if not bc.value.ca: raise ValueError("not a CA certificate") try: self.run_certutil(['-V', '-n', nickname, '-u', 'L'], capture_output=True) except ipautil.CalledProcessError as e: # certutil output in case of error is # 'certutil: certificate is invalid: \n' msg = e.output.split(': ')[2].strip() if msg == BAD_USAGE_ERR: msg = 'invalid for a CA.' raise ValueError(msg) def verify_kdc_cert_validity(self, nickname, realm): nicknames = self.get_trust_chain(nickname) certs = [self.get_cert(nickname) for nickname in nicknames] certs = [x509.load_certificate(cert, x509.DER) for cert in certs] verify_kdc_cert_validity(certs[-1], certs[:-1], realm)