name : cc_ssh_authkey_fingerprints.py # Copyright (C) 2012 Yahoo! Inc. # # Author: Joshua Harlow <harlowja@yahoo-inc.com> # # This file is part of cloud-init. See LICENSE file for license information. """SSH AuthKey Fingerprints: Log fingerprints of user SSH keys""" import base64 import hashlib import logging from cloudinit import ssh_util, util from cloudinit.cloud import Cloud from cloudinit.config import Config from cloudinit.config.schema import MetaSchema, get_meta_doc from cloudinit.distros import ALL_DISTROS, ug_util from cloudinit.settings import PER_INSTANCE from cloudinit.simpletable import SimpleTable MODULE_DESCRIPTION = """\ Write fingerprints of authorized keys for each user to log. This is enabled by default, but can be disabled using ``no_ssh_fingerprints``. The hash type for the keys can be specified, but defaults to ``sha256``. """ meta: MetaSchema = { "id": "cc_ssh_authkey_fingerprints", "name": "SSH AuthKey Fingerprints", "title": "Log fingerprints of user SSH keys", "description": MODULE_DESCRIPTION, "distros": [ALL_DISTROS], "frequency": PER_INSTANCE, "examples": [ "no_ssh_fingerprints: true", "authkey_hash: sha512", ], "activate_by_schema_keys": [], } __doc__ = get_meta_doc(meta) LOG = logging.getLogger(__name__) def _split_hash(bin_hash): split_up = [] for i in range(0, len(bin_hash), 2): split_up.append(bin_hash[i : i + 2]) return split_up def _gen_fingerprint(b64_text, hash_meth="sha256"): if not b64_text: return "" # TBD(harlowja): Maybe we should feed this into 'ssh -lf'? try: hasher = hashlib.new(hash_meth) hasher.update(base64.b64decode(b64_text)) return ":".join(_split_hash(hasher.hexdigest())) except (TypeError, ValueError): # Raised when b64 not really b64... # or when the hash type is not really # a known/supported hash type... return "?" def _is_printable_key(entry): if any([entry.keytype, entry.base64, entry.comment, entry.options]): if ( entry.keytype and entry.keytype.lower().strip() in ssh_util.VALID_KEY_TYPES ): return True return False def _pprint_key_entries( user, key_fn, key_entries, hash_meth="sha256", prefix="ci-info: " ): if not key_entries: message = ( "%sno authorized SSH keys fingerprints found for user %s.\n" % (prefix, user) ) util.multi_log(message, console=True, stderr=False) return tbl_fields = [ "Keytype", "Fingerprint (%s)" % (hash_meth), "Options", "Comment", ] tbl = SimpleTable(tbl_fields) for entry in key_entries: if _is_printable_key(entry): row = [ entry.keytype or "-", _gen_fingerprint(entry.base64, hash_meth) or "-", entry.options or "-", entry.comment or "-", ] tbl.add_row(row) authtbl_s = tbl.get_string() authtbl_lines = authtbl_s.splitlines() max_len = len(max(authtbl_lines, key=len)) lines = [ util.center( "Authorized keys from %s for user %s" % (key_fn, user), "+", max_len, ), ] lines.extend(authtbl_lines) for line in lines: util.multi_log( text="%s%s\n" % (prefix, line), stderr=False, console=True ) def handle(name: str, cfg: Config, cloud: Cloud, args: list) -> None: if util.is_true(cfg.get("no_ssh_fingerprints", False)): LOG.debug( "Skipping module named %s, logging of SSH fingerprints disabled", name, ) return hash_meth = util.get_cfg_option_str(cfg, "authkey_hash", "sha256") (users, _groups) = ug_util.normalize_users_groups(cfg, cloud.distro) for (user_name, _cfg) in users.items(): if _cfg.get("no_create_home") or _cfg.get("system"): LOG.debug( "Skipping printing of ssh fingerprints for user '%s' because " "no home directory is created", user_name, ) continue (key_fn, key_entries) = ssh_util.extract_authorized_keys(user_name) _pprint_key_entries(user_name, key_fn, key_entries, hash_meth)