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# 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
------------------------
**Summary:** log fingerprints of user SSH keys
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``.
**Internal name:** `` cc_ssh_authkey_fingerprints``
**Module frequency:** per instance
**Supported distros:** all
**Config keys**::
no_ssh_fingerprints: <true/false>
authkey_hash: <hash type>
"""
import base64
import hashlib
from cloudinit.simpletable import SimpleTable
from cloudinit.distros import ug_util
from cloudinit import ssh_util
from cloudinit import util
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-dss', 'ssh-rsa']):
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)
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, cfg, cloud, log, _args):
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():
(key_fn, key_entries) = ssh_util.extract_authorized_keys(user_name)
_pprint_key_entries(user_name, key_fn,
key_entries, hash_meth)
# vi: ts=4 expandtab
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