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Your IP : 18.221.188.161
# Authors: Simo Sorce <ssorce@redhat.com>
#
# Copyright (C) 2007 Red Hat
# see file 'COPYING' for use and warranty information
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
import socket
import os
import copy
from ipapython.ipa_log_manager import *
import tempfile
import ldap
from ldap import LDAPError
from ipapython.ipautil import run, CalledProcessError, valid_ip, get_ipa_basedn, \
realm_to_suffix, format_netloc
from ipapython.dn import DN
from ipapython import dnsclient
CACERT = '/etc/ipa/ca.crt'
NOT_FQDN = -1
NO_LDAP_SERVER = -2
REALM_NOT_FOUND = -3
NOT_IPA_SERVER = -4
NO_ACCESS_TO_LDAP = -5
NO_TLS_LDAP = -6
BAD_HOST_CONFIG = -10
UNKNOWN_ERROR = -15
error_names = {
0: 'Success',
NOT_FQDN: 'NOT_FQDN',
NO_LDAP_SERVER: 'NO_LDAP_SERVER',
REALM_NOT_FOUND: 'REALM_NOT_FOUND',
NOT_IPA_SERVER: 'NOT_IPA_SERVER',
NO_ACCESS_TO_LDAP: 'NO_ACCESS_TO_LDAP',
NO_TLS_LDAP: 'NO_TLS_LDAP',
BAD_HOST_CONFIG: 'BAD_HOST_CONFIG',
UNKNOWN_ERROR: 'UNKNOWN_ERROR',
}
class IPADiscovery(object):
def __init__(self):
self.realm = None
self.domain = None
self.server = None
self.servers = []
self.basedn = None
self.realm_source = None
self.domain_source = None
self.server_source = None
self.basedn_source = None
def __get_resolver_domains(self):
"""
Read /etc/resolv.conf and return all the domains found in domain and
search.
Returns a list of (domain, info) pairs. The info contains a reason why
the domain is returned.
"""
domains = []
domain = None
try:
fp = open('/etc/resolv.conf', 'r')
lines = fp.readlines()
fp.close()
for line in lines:
if line.lower().startswith('domain'):
domain = (line.split()[-1],
'local domain from /etc/resolv.conf')
elif line.lower().startswith('search'):
domains += [(d, 'search domain from /etc/resolv.conf') for
d in line.split()[1:]]
except:
pass
if domain:
domains = [domain] + domains
return domains
def getServerName(self):
return self.server
def getDomainName(self):
return self.domain
def getRealmName(self):
return self.realm
def getKDCName(self):
return self.kdc
def getBaseDN(self):
return self.basedn
def check_domain(self, domain, tried, reason):
"""
Given a domain search it for SRV records, breaking it down to search
all subdomains too.
Returns a tuple (servers, domain) or (None,None) if a SRV record
isn't found. servers is a list of servers found. domain is a string.
:param tried: A set of domains that were tried already
:param reason: Reason this domain is searched (included in the log)
"""
servers = None
root_logger.debug('Start searching for LDAP SRV record in "%s" (%s) ' +
'and its sub-domains', domain, reason)
while not servers:
if domain in tried:
root_logger.debug("Already searched %s; skipping", domain)
break
tried.add(domain)
servers = self.ipadns_search_srv(domain, '_ldap._tcp', 389,
break_on_first=False)
if servers:
return (servers, domain)
else:
p = domain.find(".")
if p == -1: #no ldap server found and last component of the domain already tested
return (None, None)
domain = domain[p+1:]
return (None, None)
def search(self, domain="", servers="", realm=None, hostname=None, ca_cert_path=None):
"""
Use DNS discovery to identify valid IPA servers.
servers may contain an optional list of servers which will be used
instead of discovering available LDAP SRV records.
Returns a constant representing the overall search result.
"""
root_logger.debug("[IPA Discovery]")
root_logger.debug(
'Starting IPA discovery with domain=%s, servers=%s, hostname=%s',
domain, servers, hostname)
self.server = None
autodiscovered = False
if not servers:
if not domain: #domain not provided do full DNS discovery
# get the local host name
if not hostname:
hostname = socket.getfqdn()
root_logger.debug('Hostname: %s', hostname)
if not hostname:
return BAD_HOST_CONFIG
if valid_ip(hostname):
return NOT_FQDN
# first, check for an LDAP server for the local domain
p = hostname.find(".")
if p == -1: #no domain name
return NOT_FQDN
domain = hostname[p+1:]
# Get the list of domains from /etc/resolv.conf, we'll search
# them all. We search the domain of our hostname first though.
# This is to avoid the situation where domain isn't set in
# /etc/resolv.conf and the search list has the hostname domain
# not first. We could end up with the wrong SRV record.
domains = self.__get_resolver_domains()
domains = [(domain, 'domain of the hostname')] + domains
tried = set()
for domain, reason in domains:
servers, domain = self.check_domain(domain, tried, reason)
if servers:
autodiscovered = True
self.domain = domain
self.server_source = self.domain_source = (
'Discovered LDAP SRV records from %s (%s)' %
(domain, reason))
break
if not self.domain: #no ldap server found
root_logger.debug('No LDAP server found')
return NO_LDAP_SERVER
else:
root_logger.debug("Search for LDAP SRV record in %s", domain)
servers = self.ipadns_search_srv(domain, '_ldap._tcp', 389,
break_on_first=False)
if servers:
autodiscovered = True
self.domain = domain
self.server_source = self.domain_source = (
'Discovered LDAP SRV records from %s' % domain)
else:
self.server = None
root_logger.debug('No LDAP server found')
return NO_LDAP_SERVER
else:
root_logger.debug("Server and domain forced")
self.domain = domain
self.domain_source = self.server_source = 'Forced'
#search for kerberos
root_logger.debug("[Kerberos realm search]")
if realm:
root_logger.debug("Kerberos realm forced")
self.realm = realm
self.realm_source = 'Forced'
else:
realm = self.ipadnssearchkrbrealm()
self.realm = realm
self.realm_source = (
'Discovered Kerberos DNS records from %s' % self.domain)
if not servers and not realm:
return REALM_NOT_FOUND
self.kdc = self.ipadnssearchkrbkdc()
self.kdc_source = (
'Discovered Kerberos DNS records from %s' % self.domain)
# We may have received multiple servers corresponding to the domain
# Iterate through all of those to check if it is IPA LDAP server
ldapret = [NOT_IPA_SERVER]
ldapaccess = True
root_logger.debug("[LDAP server check]")
valid_servers = []
for server in servers:
root_logger.debug('Verifying that %s (realm %s) is an IPA server',
server, self.realm)
# check ldap now
ldapret = self.ipacheckldap(server, self.realm, ca_cert_path=ca_cert_path)
if ldapret[0] == 0:
self.server = ldapret[1]
self.realm = ldapret[2]
self.server_source = self.realm_source = (
'Discovered from LDAP DNS records in %s' % self.server)
valid_servers.insert(0, server)
# verified, we actually talked to the remote server and it
# is definetely an IPA server
if autodiscovered:
# No need to keep verifying servers if we discovered them
# via DNS
break
elif ldapret[0] == NO_ACCESS_TO_LDAP or ldapret[0] == NO_TLS_LDAP:
ldapaccess = False
valid_servers.insert(0, server)
# we may set verified_servers below, we don't have it yet
if autodiscovered:
# No need to keep verifying servers if we discovered them
# via DNS
break
elif ldapret[0] == NOT_IPA_SERVER:
root_logger.warn(
'%s (realm %s) is not an IPA server', server, self.realm)
elif ldapret[0] == NO_LDAP_SERVER:
root_logger.debug(
'Unable to verify that %s (realm %s) is an IPA server',
server, self.realm)
# If one of LDAP servers checked rejects access (maybe anonymous
# bind is disabled), assume realm and basedn generated off domain.
# Note that in case ldapret[0] == 0 and ldapaccess == False (one of
# servers didn't provide access but another one succeeded), self.realm
# will be set already to a proper value above, self.basdn will be
# initialized during the LDAP check itself and we'll skip these two checks.
if not ldapaccess and self.realm is None:
# Assume realm is the same as domain.upper()
self.realm = self.domain.upper()
self.realm_source = 'Assumed same as domain'
root_logger.debug(
"Assuming realm is the same as domain: %s", self.realm)
if not ldapaccess and self.basedn is None:
# Generate suffix from realm
self.basedn = realm_to_suffix(self.realm)
self.basedn_source = 'Generated from Kerberos realm'
root_logger.debug("Generated basedn from realm: %s" % self.basedn)
root_logger.debug(
"Discovery result: %s; server=%s, domain=%s, kdc=%s, basedn=%s",
error_names.get(ldapret[0], ldapret[0]),
self.server, self.domain, self.kdc, self.basedn)
root_logger.debug("Validated servers: %s" % ','.join(valid_servers))
self.servers = valid_servers
# If we have any servers left then override the last return value
# to indicate success.
if valid_servers:
self.server = servers[0]
ldapret[0] = 0
return ldapret[0]
def ipacheckldap(self, thost, trealm, ca_cert_path=None):
"""
Given a host and kerberos realm verify that it is an IPA LDAP
server hosting the realm.
Returns a list [errno, host, realm] or an empty list on error.
Errno is an error number:
0 means all ok
1 means we could not check the info in LDAP (may happend when
anonymous binds are disabled)
2 means the server is certainly not an IPA server
"""
lrealms = []
i = 0
#now verify the server is really an IPA server
try:
ldap_url = "ldap://" + format_netloc(thost, 389)
root_logger.debug("Init LDAP connection with: %s", ldap_url)
lh = ldap.initialize(ldap_url)
if ca_cert_path:
ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, True)
ldap.set_option(ldap.OPT_X_TLS_CACERTFILE, ca_cert_path)
lh.set_option(ldap.OPT_X_TLS_DEMAND, True)
lh.start_tls_s()
lh.set_option(ldap.OPT_PROTOCOL_VERSION, 3)
lh.simple_bind_s("","")
# get IPA base DN
root_logger.debug("Search LDAP server for IPA base DN")
basedn = get_ipa_basedn(lh)
if basedn is None:
root_logger.debug("The server is not an IPA server")
return [NOT_IPA_SERVER]
self.basedn = basedn
self.basedn_source = 'From IPA server %s' % ldap_url
#search and return known realms
root_logger.debug(
"Search for (objectClass=krbRealmContainer) in %s (sub)",
self.basedn)
lret = lh.search_s(str(DN(('cn', 'kerberos'), self.basedn)), ldap.SCOPE_SUBTREE, "(objectClass=krbRealmContainer)")
if not lret:
#something very wrong
return [REALM_NOT_FOUND]
for lres in lret:
root_logger.debug("Found: %s", lres[0])
for lattr in lres[1]:
if lattr.lower() == "cn":
lrealms.append(lres[1][lattr][0])
if trealm:
for r in lrealms:
if trealm == r:
return [0, thost, trealm]
# must match or something is very wrong
return [REALM_NOT_FOUND]
else:
if len(lrealms) != 1:
#which one? we can't attach to a multi-realm server without DNS working
return [REALM_NOT_FOUND]
else:
return [0, thost, lrealms[0]]
#we shouldn't get here
return [UNKNOWN_ERROR]
except LDAPError, err:
if isinstance(err, ldap.TIMEOUT):
root_logger.debug("LDAP Error: timeout")
return [NO_LDAP_SERVER]
if isinstance(err, ldap.SERVER_DOWN):
root_logger.debug("LDAP Error: server down")
return [NO_LDAP_SERVER]
if isinstance(err, ldap.INAPPROPRIATE_AUTH):
root_logger.debug("LDAP Error: Anonymous access not allowed")
return [NO_ACCESS_TO_LDAP]
# We should only get UNWILLING_TO_PERFORM if the remote LDAP server
# has minssf > 0 and we have attempted a non-TLS connection.
if ca_cert_path is None and isinstance(err, ldap.UNWILLING_TO_PERFORM):
root_logger.debug("LDAP server returned UNWILLING_TO_PERFORM. This likely means that minssf is enabled")
return [NO_TLS_LDAP]
root_logger.error("LDAP Error: %s: %s" %
(err.args[0]['desc'], err.args[0].get('info', '')))
return [UNKNOWN_ERROR]
def ipadns_search_srv(self, domain, srv_record_name, default_port,
break_on_first=True):
"""
Search for SRV records in given domain. When no record is found,
en empty list is returned
:param domain: Search domain name
:param srv_record_name: SRV record name, e.g. "_ldap._tcp"
:param default_port: When default_port is not None, it is being
checked with the port in SRV record and if they don't
match, the port from SRV record is appended to
found hostname in this format: "hostname:port"
:param break_on_first: break on the first find and return just one
entry
"""
servers = []
qname = '%s.%s' % (srv_record_name, domain)
if not qname.endswith("."):
qname += "."
root_logger.debug("Search DNS for SRV record of %s", qname)
results = dnsclient.query(qname, dnsclient.DNS_C_IN, dnsclient.DNS_T_SRV)
if not results:
root_logger.debug("No DNS record found")
for result in results:
if result.dns_type == dnsclient.DNS_T_SRV:
root_logger.debug("DNS record found: %s", result)
server = result.rdata.server.rstrip(".")
if not server:
root_logger.debug("Cannot parse the hostname from SRV record: %s", result)
continue
if default_port is not None and \
result.rdata.port and result.rdata.port != default_port:
server = "%s:%s" % (server, result.rdata.port)
servers.append(server)
if break_on_first:
break
return servers
def ipadnssearchkrbrealm(self, domain=None):
realm = None
if not domain:
domain = self.domain
# now, check for a Kerberos realm the local host or domain is in
qname = "_kerberos." + domain
if not qname.endswith("."):
qname += "."
root_logger.debug("Search DNS for TXT record of %s", qname)
results = dnsclient.query(qname, dnsclient.DNS_C_IN, dnsclient.DNS_T_TXT)
if not results:
root_logger.debug("No DNS record found")
for result in results:
if result.dns_type == dnsclient.DNS_T_TXT:
root_logger.debug("DNS record found: %s", result)
if result.rdata.data:
realm = result.rdata.data
if realm:
break
return realm
def ipadnssearchkrbkdc(self, domain=None):
kdc = None
if not domain:
domain = self.domain
kdc = self.ipadns_search_srv(domain, '_kerberos._udp', 88,
break_on_first=False)
if kdc:
kdc = ','.join(kdc)
else:
root_logger.debug("SRV record for KDC not found! Domain: %s" % domain)
kdc = None
return kdc