"""This module manages ssh key files for bcfg2""" import re import os import sys import socket import shutil import logging import tempfile from itertools import chain from subprocess import Popen, PIPE import Bcfg2.Server.Plugin from Bcfg2.Server.Plugin import PluginExecutionError from Bcfg2.Compat import any, u_str, b64encode # pylint: disable=W0622 LOGGER = logging.getLogger(__name__) class KeyData(Bcfg2.Server.Plugin.SpecificData): """ class to handle key data for HostKeyEntrySet """ def __init__(self, name, specific, encoding): Bcfg2.Server.Plugin.SpecificData.__init__(self, name, specific, encoding) self.encoding = encoding def __lt__(self, other): return self.name < other.name def bind_entry(self, entry, _): """ Bind the entry with the data of this key :param entry: The abstract entry to bind. This will be modified in place. :type entry: lxml.etree._Element :returns: None """ entry.set('type', 'file') if entry.get('encoding') == 'base64': entry.text = b64encode(self.data) else: try: entry.text = u_str(self.data, self.encoding) except UnicodeDecodeError: msg = "Failed to decode %s: %s" % (entry.get('name'), sys.exc_info()[1]) LOGGER.error(msg) LOGGER.error("Please verify you are using the proper encoding") raise Bcfg2.Server.Plugin.PluginExecutionError(msg) except ValueError: msg = "Error in specification for %s: %s" % (entry.get('name'), sys.exc_info()[1]) LOGGER.error(msg) LOGGER.error("You need to specify base64 encoding for %s" % entry.get('name')) raise Bcfg2.Server.Plugin.PluginExecutionError(msg) if entry.text in ['', None]: entry.set('empty', 'true') class HostKeyEntrySet(Bcfg2.Server.Plugin.EntrySet): """ EntrySet to handle all kinds of host keys """ def __init__(self, basename, path): if basename.startswith("ssh_host_key"): encoding = "base64" else: encoding = None Bcfg2.Server.Plugin.EntrySet.__init__(self, basename, path, KeyData, encoding) self.metadata = {'owner': 'root', 'group': 'root', 'type': 'file'} if encoding is not None: self.metadata['encoding'] = encoding if basename.endswith('.pub'): self.metadata['mode'] = '0644' else: self.metadata['mode'] = '0600' class KnownHostsEntrySet(Bcfg2.Server.Plugin.EntrySet): """ EntrySet to handle the ssh_known_hosts file """ def __init__(self, path): Bcfg2.Server.Plugin.EntrySet.__init__(self, "ssh_known_hosts", path, KeyData, None) self.metadata = {'owner': 'root', 'group': 'root', 'type': 'file', 'mode': '0644'} class SSHbase(Bcfg2.Server.Plugin.Plugin, Bcfg2.Server.Plugin.Caching, Bcfg2.Server.Plugin.Generator, Bcfg2.Server.Plugin.PullTarget): """ The sshbase generator manages ssh host keys (both v1 and v2) for hosts. It also manages the ssh_known_hosts file. It can integrate host keys from other management domains and similarly export its keys. The repository contains files in the following formats: ssh_host_key.H_(hostname) -> the v1 host private key for (hostname) ssh_host_key.pub.H_(hostname) -> the v1 host public key for (hostname) ssh_host_(ec)(dr)sa_key.H_(hostname) -> the v2 ssh host private key for (hostname) ssh_host_(ec)(dr)sa_key.pub.H_(hostname) -> the v2 ssh host public key for (hostname) ssh_known_hosts -> the current known hosts file. this is regenerated each time a new key is generated. """ __author__ = 'bcfg-dev@mcs.anl.gov' keypatterns = ["ssh_host_dsa_key", "ssh_host_ecdsa_key", "ssh_host_rsa_key", "ssh_host_key", "ssh_host_dsa_key.pub", "ssh_host_ecdsa_key.pub", "ssh_host_rsa_key.pub", "ssh_host_key.pub"] def __init__(self, core, datastore): Bcfg2.Server.Plugin.Plugin.__init__(self, core, datastore) Bcfg2.Server.Plugin.Caching.__init__(self) Bcfg2.Server.Plugin.Generator.__init__(self) Bcfg2.Server.Plugin.PullTarget.__init__(self) self.ipcache = {} self.namecache = {} self.__skn = False # keep track of which bogus keys we've warned about, and only # do so once self.badnames = dict() core.fam.AddMonitor(self.data, self) self.static = dict() self.entries = dict() self.Entries['Path'] = dict() self.entries['/etc/ssh/ssh_known_hosts'] = \ KnownHostsEntrySet(self.data) self.Entries['Path']['/etc/ssh/ssh_known_hosts'] = self.build_skn for keypattern in self.keypatterns: self.entries["/etc/ssh/" + keypattern] = \ HostKeyEntrySet(keypattern, self.data) self.Entries['Path']["/etc/ssh/" + keypattern] = self.build_hk def expire_cache(self, key=None): self.__skn = False def get_skn(self): """Build memory cache of the ssh known hosts file.""" if not self.__skn: # if no metadata is registered yet, defer if len(self.core.metadata.query.all()) == 0: self.__skn = False return self.__skn skn = [s.data.rstrip() for s in list(self.static.values())] mquery = self.core.metadata.query # build hostname cache names = dict() for cmeta in mquery.all(): names[cmeta.hostname] = set([cmeta.hostname]) names[cmeta.hostname].update(cmeta.aliases) newnames = set() newips = set() for name in names[cmeta.hostname]: newnames.add(name.split('.')[0]) try: newips.update(self.get_ipcache_entry(name)[0]) except: # pylint: disable=W0702 continue names[cmeta.hostname].update(newnames) names[cmeta.hostname].update(cmeta.addresses) names[cmeta.hostname].update(newips) # TODO: Only perform reverse lookups on IPs if an # option is set. if True: for ip in newips: try: names[cmeta.hostname].update( self.get_namecache_entry(ip)) except: # pylint: disable=W0702 continue names[cmeta.hostname] = sorted(names[cmeta.hostname]) pubkeys = [pubk for pubk in list(self.entries.keys()) if pubk.endswith('.pub')] pubkeys.sort() for pubkey in pubkeys: for entry in sorted(self.entries[pubkey].entries.values(), key=lambda e: (e.specific.hostname or e.specific.group)): specific = entry.specific hostnames = [] if specific.hostname and specific.hostname in names: hostnames = names[specific.hostname] elif specific.group: hostnames = list( chain( *[names[cmeta.hostname] for cmeta in mquery.by_groups([specific.group])])) elif specific.all: # a generic key for all hosts? really? hostnames = list(chain(*list(names.values()))) if not hostnames: if specific.hostname: key = specific.hostname ktype = "host" elif specific.group: key = specific.group ktype = "group" else: # user has added a global SSH key, but # have no clients yet. don't warn about # this. continue if key not in self.badnames: self.badnames[key] = True self.logger.info("Ignoring key for unknown %s %s" % (ktype, key)) continue skn.append("%s %s" % (','.join(hostnames), entry.data.rstrip())) self.__skn = "\n".join(skn) + "\n" return self.__skn def set_skn(self, value): """Set backing data for skn.""" self.__skn = value skn = property(get_skn, set_skn) def HandleEvent(self, event=None): """Local event handler that does skn regen on pubkey change.""" # skip events we don't care about action = event.code2str() if action == "endExist" or event.filename == self.data: return for entry in list(self.entries.values()): if entry.specific.match(event.filename): entry.handle_event(event) if any(event.filename.startswith(kp) for kp in self.keypatterns if kp.endswith(".pub")): self.debug_log("New public key %s; invalidating " "ssh_known_hosts cache" % event.filename) self.skn = False return if event.filename in ['info', 'info.xml', ':info']: for entry in list(self.entries.values()): entry.handle_event(event) return if event.filename.endswith('.static'): self.logger.info("Static key %s %s; invalidating ssh_known_hosts " "cache" % (event.filename, action)) if action == "deleted" and event.filename in self.static: del self.static[event.filename] self.skn = False else: self.static[event.filename] = Bcfg2.Server.Plugin.FileBacked( os.path.join(self.data, event.filename)) self.static[event.filename].HandleEvent(event) self.skn = False return self.logger.warn("SSHbase: Got unknown event %s %s" % (event.filename, action)) def get_ipcache_entry(self, client): """Build a cache of dns results.""" if client in self.ipcache: if self.ipcache[client]: return self.ipcache[client] else: raise socket.gaierror else: # need to add entry try: ipaddr = set([info[4][0] for info in socket.getaddrinfo(client, None)]) self.ipcache[client] = (ipaddr, client) return (ipaddr, client) except socket.gaierror: ipaddr = Popen(["getent", "hosts", client], stdout=PIPE).stdout.read().strip().split() if ipaddr: self.ipcache[client] = (ipaddr, client) return (ipaddr, client) self.ipcache[client] = False self.logger.error("Failed to find IP address for %s" % client) raise socket.gaierror def get_namecache_entry(self, cip): """Build a cache of name lookups from client IP addresses.""" if cip in self.namecache: # lookup cached name from IP if self.namecache[cip]: return self.namecache[cip] else: raise socket.gaierror else: # add an entry that has not been cached try: rvlookup = socket.gethostbyaddr(cip) if rvlookup[0]: self.namecache[cip] = [rvlookup[0]] else: self.namecache[cip] = [] self.namecache[cip].extend(rvlookup[1]) return self.namecache[cip] except socket.gaierror: self.namecache[cip] = False self.logger.error("Failed to find any names associated with " "IP address %s" % cip) raise def build_skn(self, entry, metadata): """This function builds builds a host specific known_hosts file.""" try: self.entries[entry.get('name')].bind_entry(entry, metadata) except Bcfg2.Server.Plugin.PluginExecutionError: entry.text = self.skn hostkeys = [] for key in self.keypatterns: if key.endswith(".pub"): try: hostkeys.append( self.entries["/etc/ssh/" + key].best_matching(metadata)) except Bcfg2.Server.Plugin.PluginExecutionError: pass hostkeys.sort() for hostkey in hostkeys: entry.text += "localhost,localhost.localdomain,127.0.0.1 %s" \ % hostkey.data self.entries[entry.get('name')].bind_info_to_entry(entry, metadata) def build_hk(self, entry, metadata): """This binds host key data into entries.""" try: self.entries[entry.get('name')].bind_entry(entry, metadata) except Bcfg2.Server.Plugin.PluginExecutionError: filename = entry.get('name').split('/')[-1] self.GenerateHostKeyPair(metadata.hostname, filename) # Service the FAM events queued up by the key generation # so the data structure entries will be available for # binding. # # NOTE: We wait for up to ten seconds. There is some # potential for race condition, because if the file # monitor doesn't get notified about the new key files in # time, those entries won't be available for binding. In # practice, this seems "good enough". tries = 0 is_bound = False while not is_bound: if tries >= 10: msg = "%s still not registered" % filename self.logger.error(msg) raise Bcfg2.Server.Plugin.PluginExecutionError(msg) self.core.fam.handle_events_in_interval(1) tries += 1 try: self.entries[entry.get('name')].bind_entry(entry, metadata) is_bound = True except Bcfg2.Server.Plugin.PluginExecutionError: pass def GenerateHostKeyPair(self, client, filename): """Generate new host key pair for client.""" match = re.search(r'(ssh_host_(?:((?:ecd|d|r)sa)_)?key)', filename) if match: hostkey = "%s.H_%s" % (match.group(1), client) if match.group(2): keytype = match.group(2) else: keytype = 'rsa1' else: raise PluginExecutionError("Unknown key filename: %s" % filename) fileloc = os.path.join(self.data, hostkey) publoc = os.path.join(self.data, ".".join([hostkey.split('.')[0], 'pub', "H_%s" % client])) tempdir = tempfile.mkdtemp() temploc = os.path.join(tempdir, hostkey) cmd = ["ssh-keygen", "-q", "-f", temploc, "-N", "", "-t", keytype, "-C", "root@%s" % client] self.debug_log("SSHbase: Running: %s" % " ".join(cmd)) proc = Popen(cmd, stdout=PIPE, stdin=PIPE) err = proc.communicate()[1] if proc.wait(): raise PluginExecutionError("SSHbase: Error running ssh-keygen: %s" % err) try: shutil.copy(temploc, fileloc) shutil.copy("%s.pub" % temploc, publoc) except IOError: err = sys.exc_info()[1] raise PluginExecutionError("Temporary SSH keys not found: %s" % err) try: os.unlink(temploc) os.unlink("%s.pub" % temploc) os.rmdir(tempdir) except OSError: err = sys.exc_info()[1] raise PluginExecutionError("Failed to unlink temporary ssh keys: " "%s" % err) def AcceptChoices(self, _, metadata): return [Bcfg2.Server.Plugin.Specificity(hostname=metadata.hostname)] def AcceptPullData(self, specific, entry, log): """Per-plugin bcfg2-admin pull support.""" # specific will always be host specific filename = os.path.join(self.data, "%s.H_%s" % (entry['name'].split('/')[-1], specific.hostname)) try: open(filename, 'w').write(entry['text']) if log: print("Wrote file %s" % filename) except KeyError: self.logger.error("Failed to pull %s. This file does not " "currently exist on the client" % entry.get('name'))