"""This module manages ssh key files for bcfg2""" import re import os import sys import socket import shutil import tempfile import lxml.etree import Bcfg2.Options import Bcfg2.Server.Plugin from itertools import chain from Bcfg2.Utils import Executor from Bcfg2.Server.Plugin import PluginExecutionError from Bcfg2.Compat import any, u_str, b64encode # pylint: disable=W0622 try: from Bcfg2.Server.Encryption import ssl_encrypt, bruteforce_decrypt, \ EVPError HAS_CRYPTO = True except ImportError: HAS_CRYPTO = False class KeyData(Bcfg2.Server.Plugin.SpecificData): """ class to handle key data for HostKeyEntrySet """ 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, Bcfg2.Options.setup.encoding) except UnicodeDecodeError: msg = "Failed to decode %s: %s" % (entry.get('name'), sys.exc_info()[1]) self.logger.error(msg) self.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]) self.logger.error(msg) self.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') def handle_event(self, event): Bcfg2.Server.Plugin.SpecificData.handle_event(self, event) if event.filename.endswith(".crypt"): if self.data is None: return # todo: let the user specify a passphrase by name try: self.data = bruteforce_decrypt(self.data) except EVPError: raise PluginExecutionError("Failed to decrypt %s" % self.name) class HostKeyEntrySet(Bcfg2.Server.Plugin.EntrySet): """ EntrySet to handle all kinds of host keys """ def __init__(self, basename, path): Bcfg2.Server.Plugin.EntrySet.__init__(self, basename, path, KeyData) self.metadata = {'owner': 'root', 'group': 'root', 'type': 'file'} if basename.startswith("ssh_host_key"): self.metadata['encoding'] = "base64" if basename.endswith('.pub'): self.metadata['mode'] = '0644' else: self.metadata['mode'] = '0600' def specificity_from_filename(self, fname, specific=None): if fname.endswith(".crypt"): fname = fname[0:-6] return Bcfg2.Server.Plugin.EntrySet.specificity_from_filename( self, fname, specific=specific) 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) self.metadata = {'owner': 'root', 'group': 'root', 'type': 'file', 'mode': '0644'} class SSHbase(Bcfg2.Server.Plugin.Plugin, Bcfg2.Server.Plugin.Connector, 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"] options = [ Bcfg2.Options.Option( cf=("sshbase", "passphrase"), dest="sshbase_passphrase", help="Passphrase used to encrypt generated private SSH host keys")] def __init__(self, core): Bcfg2.Server.Plugin.Plugin.__init__(self, core) Bcfg2.Server.Plugin.Connector.__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() self.fam = Bcfg2.Server.FileMonitor.get_fam() self.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 self.cmd = Executor() @property def passphrase(self): """ The passphrase used to encrypt private keys """ if HAS_CRYPTO and Bcfg2.Options.setup.sshbase_passphrase: return Bcfg2.Options.setup.passphrases[ Bcfg2.Options.setup.sshbase_passphrase] return None 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 PluginExecutionError: 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. for ip in newips: try: names[cmeta.hostname].update( self.get_namecache_entry(ip)) except socket.herror: 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 event.filename.endswith(".crypt"): fname = event.filename[0:-6] else: fname = event.filename if entry.specific.match(fname): 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 if self.core.metadata_cache_mode in ['cautious', 'aggressive']: self.core.metadata_cache.expire() return if event.filename == 'info.xml': 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 PluginExecutionError("No cached IP address for %s" % client) 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: result = self.cmd.run(["getent", "hosts", client]) if result.success: ipaddr = result.stdout.strip().split() if ipaddr: self.ipcache[client] = (ipaddr, client) return (ipaddr, client) self.ipcache[client] = False msg = "Failed to find IP address for %s: %s" % (client, result.error) self.logger.error(msg) raise PluginExecutionError(msg) 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.herror 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.herror: 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.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: print("Failed to bind %s: %s") % ( lxml.etree.tostring(entry), sys.exc_info()[1]) 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)) result = self.cmd.run(cmd) if not result.success: raise PluginExecutionError("SSHbase: Error running ssh-keygen: %s" % result.error) if self.passphrase: self.debug_log("SSHbase: Encrypting private key for %s" % fileloc) try: data = ssl_encrypt(open(temploc).read(), self.passphrase) except IOError: raise PluginExecutionError("Unable to read temporary SSH key: " "%s" % sys.exc_info()[1]) except EVPError: raise PluginExecutionError("Unable to encrypt SSH key: %s" % sys.exc_info()[1]) try: open("%s.crypt" % fileloc, "wb").write(data) except IOError: raise PluginExecutionError("Unable to write encrypted SSH " "key: %s" % sys.exc_info()[1]) try: if not self.passphrase: shutil.copy(temploc, fileloc) shutil.copy("%s.pub" % temploc, publoc) except IOError: raise PluginExecutionError("Unable to copy temporary SSH key: %s" % sys.exc_info()[1]) 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')) def get_additional_data(self, metadata): data = dict() for key in self.keypatterns: if key.endswith(".pub"): try: keyfile = "/etc/ssh/" + key entry = self.entries[keyfile].best_matching(metadata) data[key] = entry.data except Bcfg2.Server.Plugin.PluginExecutionError: pass return data