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'''This module manages ssh key files for bcfg2'''
__revision__ = '$Revision$'
from binascii import b2a_base64
from os import rename, system, popen
from socket import gethostbyname, gaierror
from Bcfg2.Server.Plugin import Plugin, DirectoryBacked
class SSHbase(Plugin):
'''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"]
def __init__(self, core, datastore):
Plugin.__init__(self, core, datastore)
self.repository = DirectoryBacked(self.data, self.core.fam)
try:
prefix = open("%s/prefix" % (self.data)).read().strip()
except IOError:
prefix = ''
self.Entries = {'ConfigFile':
{prefix + '/etc/ssh/ssh_known_hosts':self.build_skn,
prefix + '/etc/ssh/ssh_host_dsa_key':self.build_hk,
prefix + '/etc/ssh/ssh_host_rsa_key':self.build_hk,
prefix + '/etc/ssh/ssh_host_dsa_key.pub':self.build_hk,
prefix + '/etc/ssh/ssh_host_rsa_key.pub':self.build_hk,
prefix + '/etc/ssh/ssh_host_key':self.build_hk,
prefix + '/etc/ssh/ssh_host_key.pub':self.build_hk}}
self.ipcache = {}
def get_ipcache_entry(self, client):
'''build a cache of dns results'''
if self.ipcache.has_key(client):
return self.ipcache[client]
else:
# need to add entry
try:
ipaddr = gethostbyname(client)
self.ipcache[client] = (ipaddr, client)
return (ipaddr, client)
except gaierror:
pass
try:
ipaddr = popen("getent hosts %s" % client).read().strip().split()
except:
ipaddr = ''
if ipaddr:
self.ipcache[client] = (ipaddr, client)
return (ipaddr, client)
self.LogError("Failed to find IP address for %s" % client)
raise gaierror
def cache_skn(self):
'''build memory cache of the ssh known hosts file'''
self.static_skn = ''
for pubkey in [pubk for pubk in self.repository.entries.keys() if pubk.find('.pub.H_') != -1]:
hostname = pubkey.split('H_')[1]
try:
(ipaddr, fqdn) = self.get_ipcache_entry(hostname)
except gaierror:
continue
shortname = hostname.split('.')[0]
self.static_skn += "%s,%s,%s %s" % (shortname, fqdn, ipaddr,
self.repository.entries[pubkey].data)
def build_skn(self, entry, metadata):
'''This function builds builds a host specific known_hosts file'''
client = metadata.hostname
if not hasattr(self, 'static_skn'):
self.cache_skn()
entry.text = self.static_skn
for hostkey in [keytmpl % client for keytmpl in self.pubkeys]:
entry.text += "localhost,localhost.localdomain,127.0.0.1 %s" % (
self.repository.entries[hostkey].data)
entry.attrib.update({'owner':'root', 'group':'root', 'perms':'0644'})
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 self.repository.entries.keys():
self.GenerateHostKeys(client)
if hasattr(self, 'static_skn'):
del self.static_skn
keydata = self.repository.entries[filename].data
perms = '0600'
if entry.get('name')[-4:] == '.pub':
perms = '0644'
entry.attrib.update({'owner':'root', 'group':'root', 'perms':perms})
entry.text = keydata
if "ssh_host_key.H_" == filename[:15]:
entry.attrib['encoding'] = 'base64'
entry.text = b2a_base64(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 self.repository.entries.keys():
fileloc = "%s/%s" % (self.data, hostkey)
system('ssh-keygen -q -f %s -N "" -t %s -C root@%s < /dev/null' % (fileloc, keytype, client))
rename("%s.pub"%(fileloc),"%s/" %
(self.data, )+".".join(hostkey.split('.')[:-1]+['pub']+[hostkey.split('.')[-1]]))
self.repository.AddEntry(hostkey)
self.repository.AddEntry("%s.pub"%(hostkey))
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