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'''This module manages ssh key files for bcfg2'''
__revision__ = '$Revision$'
import binascii
import os
import socket
import shutil
import tempfile
from subprocess import Popen, PIPE
import Bcfg2.Server.Plugin
class SSHbase(Bcfg2.Server.Plugin.Plugin,
Bcfg2.Server.Plugin.Generator,
Bcfg2.Server.Plugin.DirectoryBacked,
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_(dr)sa_key.H_(hostname) -> the v2 ssh host
private key for (hostname)
ssh_host_(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.
"""
name = 'SSHbase'
__version__ = '$Id$'
__author__ = 'bcfg-dev@mcs.anl.gov'
pubkeys = ["ssh_host_dsa_key.pub.H_%s",
"ssh_host_rsa_key.pub.H_%s", "ssh_host_key.pub.H_%s"]
hostkeys = ["ssh_host_dsa_key.H_%s",
"ssh_host_rsa_key.H_%s", "ssh_host_key.H_%s"]
keypatterns = ['ssh_host_dsa_key', 'ssh_host_rsa_key', 'ssh_host_key',
'ssh_host_dsa_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.Generator.__init__(self)
Bcfg2.Server.Plugin.PullTarget.__init__(self)
try:
Bcfg2.Server.Plugin.DirectoryBacked.__init__(self, self.data,
self.core.fam)
except OSError, ioerr:
self.logger.error("Failed to load SSHbase repository from %s" \
% (self.data))
self.logger.error(ioerr)
raise Bcfg2.Server.Plugin.PluginInitError
self.Entries = {'Path':
{'/etc/ssh/ssh_known_hosts': self.build_skn,
'/etc/ssh/ssh_host_dsa_key': self.build_hk,
'/etc/ssh/ssh_host_rsa_key': self.build_hk,
'/etc/ssh/ssh_host_dsa_key.pub': self.build_hk,
'/etc/ssh/ssh_host_rsa_key.pub': self.build_hk,
'/etc/ssh/ssh_host_key': self.build_hk,
'/etc/ssh/ssh_host_key.pub': self.build_hk}}
self.ipcache = {}
self.namecache = {}
self.__skn = False
def get_skn(self):
"""Build memory cache of the ssh known hosts file."""
if not self.__skn:
self.__skn = "\n".join([value.data for key, value in \
list(self.entries.items()) if \
key.endswith('.static')])
names = dict()
# if no metadata is registered yet, defer
if len(self.core.metadata.query.all()) == 0:
self.__skn = False
return self.__skn
for cmeta in self.core.metadata.query.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.add(self.get_ipcache_entry(name)[0])
except:
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:
continue
names[cmeta.hostname] = sorted(names[cmeta.hostname])
# now we have our name cache
pubkeys = [pubk for pubk in list(self.entries.keys()) \
if pubk.find('.pub.H_') != -1]
pubkeys.sort()
badnames = set()
for pubkey in pubkeys:
hostname = pubkey.split('H_')[1]
if hostname not in names:
if hostname not in badnames:
badnames.add(hostname)
self.logger.error("SSHbase: Unknown host %s; ignoring public keys" % hostname)
continue
self.__skn += "%s %s" % (','.join(names[hostname]),
self.entries[pubkey].data)
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."""
Bcfg2.Server.Plugin.DirectoryBacked.HandleEvent(self, event)
if event and '_key.pub.H_' in event.filename:
self.skn = False
if event and event.filename.endswith('.static'):
self.skn = False
if not self.__skn:
if (len(list(self.entries.keys()))) >= (len(os.listdir(self.data)) - 1):
_ = self.skn
def HandlesEntry(self, entry, _):
"""Handle key entries dynamically."""
return entry.tag == 'Path' and \
([fpat for fpat in self.keypatterns
if entry.get('name').endswith(fpat)]
or entry.get('name').endswith('ssh_known_hosts'))
def HandleEntry(self, entry, metadata):
"""Bind data."""
if entry.get('name').endswith('ssh_known_hosts'):
return self.build_skn(entry, metadata)
else:
return self.build_hk(entry, metadata)
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 = socket.gethostbyname(client)
self.ipcache[client] = (ipaddr, client)
return (ipaddr, client)
except socket.gaierror:
cmd = "getent hosts %s" % client
ipaddr = Popen(cmd, shell=True, \
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."""
client = metadata.hostname
entry.text = self.skn
hostkeys = [keytmpl % client for keytmpl in self.pubkeys \
if (keytmpl % client) in self.entries]
hostkeys.sort()
for hostkey in hostkeys:
entry.text += "localhost,localhost.localdomain,127.0.0.1 %s" % (
self.entries[hostkey].data)
permdata = {'owner': 'root',
'group': 'root',
'type': 'file',
'perms': '0644'}
[entry.attrib.__setitem__(key, permdata[key]) for key in permdata]
def build_hk(self, entry, metadata):
"""This binds host key data into entries."""
client = metadata.hostname
filename = "%s.H_%s" % (entry.get('name').split('/')[-1], client)
if filename not in list(self.entries.keys()):
self.GenerateHostKeys(client)
if not filename in self.entries:
self.logger.error("%s still not registered" % filename)
raise Bcfg2.Server.Plugin.PluginExecutionError
keydata = self.entries[filename].data
permdata = {'owner': 'root',
'group': 'root',
'type': 'file',
'perms': '0600'}
if entry.get('name')[-4:] == '.pub':
permdata['perms'] = '0644'
[entry.attrib.__setitem__(key, permdata[key]) for key in permdata]
if "ssh_host_key.H_" == filename[:15]:
entry.attrib['encoding'] = 'base64'
entry.text = binascii.b2a_base64(keydata)
else:
entry.text = keydata
def GenerateHostKeys(self, client):
"""Generate new host keys for client."""
keylist = [keytmpl % client for keytmpl in self.hostkeys]
for hostkey in keylist:
if 'ssh_host_rsa_key.H_' == hostkey[:19]:
keytype = 'rsa'
elif 'ssh_host_dsa_key.H_' == hostkey[:19]:
keytype = 'dsa'
else:
keytype = 'rsa1'
if hostkey not in list(self.entries.keys()):
fileloc = "%s/%s" % (self.data, hostkey)
publoc = self.data + '/' + ".".join([hostkey.split('.')[0],
'pub',
"H_%s" % client])
tempdir = tempfile.mkdtemp()
temploc = "%s/%s" % (tempdir, hostkey)
cmd = 'ssh-keygen -q -f %s -N "" -t %s -C root@%s < /dev/null'
os.system(cmd % (temploc, keytype, client))
shutil.copy(temploc, fileloc)
shutil.copy("%s.pub" % temploc, publoc)
self.AddEntry(hostkey)
self.AddEntry(".".join([hostkey.split('.')[0]] + ['pub', "H_%s" \
% client]))
try:
os.unlink(temploc)
os.unlink("%s.pub" % temploc)
os.rmdir(tempdir)
except OSError:
self.logger.error("Failed to unlink temporary ssh keys")
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 = "%s/%s.H_%s" % (self.data, 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'))
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