# Authors: Simo Sorce # # 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 . # import socket import os import logging import ipapython.dnsclient import tempfile import ldap from ldap import LDAPError from ipapython.ipautil import run, CalledProcessError, valid_ip, get_ipa_basedn, \ realm_to_suffix NOT_FQDN = -1 NO_LDAP_SERVER = -2 REALM_NOT_FOUND = -3 NOT_IPA_SERVER = -4 NO_ACCESS_TO_LDAP = -5 BAD_HOST_CONFIG = -10 UNKNOWN_ERROR = -15 class IPADiscovery: def __init__(self): self.realm = None self.domain = None self.server = None self.basedn = None def __get_resolver_domains(self): """ Read /etc/resolv.conf and return all the domains found in domain and search. Returns a list """ 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(None)[-1] elif line.lower().startswith('search'): domains = domains + line.split(None)[1:] except: pass if domain and not domain in domains: 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): """ Given a domain search it for SRV records, breaking it down to search all subdomains too. Returns a tuple (server, domain) or (None,None) if a SRV record isn't found. """ server = None while not server: logging.debug("[ipadnssearchldap("+domain+")]") server = self.ipadnssearchldap(domain) if server: return (server, 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 = "", server = "", hostname=None): qname = "" results = [] result = [] krbret = [] ldapret = [] if not server: if not domain: #domain not provided do full DNS discovery # get the local host name if not hostname: hostname = socket.getfqdn() 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, # even if that means searching it twice. 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] + domains for domain in domains: (server, domain) = self.check_domain(domain) if server: self.server = server self.domain = domain break if not self.domain: #no ldap server found return NO_LDAP_SERVER else: logging.debug("[ipadnssearchldap]") self.server = self.ipadnssearchldap(domain) if self.server: self.domain = domain else: return NO_LDAP_SERVER else: #server forced on us, this means DNS doesn't work :/ self.domain = domain self.server = server #search for kerberos logging.debug("[ipadnssearchkrb]") krbret = self.ipadnssearchkrb(self.domain) if not server and not krbret[0]: return REALM_NOT_FOUND self.realm = krbret[0] self.kdc = krbret[1] logging.debug("[ipacheckldap]") # check ldap now ldapret = self.ipacheckldap(self.server, self.realm) if ldapret[0] == 0: self.server = ldapret[1] self.realm = ldapret[2] if ldapret[0] == NO_ACCESS_TO_LDAP and self.realm is None: # Assume realm is the same as domain.upper() self.realm = self.domain.upper() logging.debug("Assuming realm is the same as domain: %s" % self.realm) if ldapret[0] == NO_ACCESS_TO_LDAP and self.basedn is None: # Generate suffix from realm self.basedn = realm_to_suffix(self.realm) logging.debug("Generate basedn from realm: %s" % self.basedn) return ldapret[0] def ipacheckldap(self, thost, trealm): """ Given a host and kerberos realm verify that it is an IPA LDAP server hosting the realm. The connection is an SSL connection so the remote IPA CA cert must be available at http://HOST/ipa/config/ca.crt 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 siabled) 2 means the server is certainly not an IPA server """ lret = [] lres = [] lattr = "" linfo = "" lrealms = [] i = 0 # Get the CA certificate try: # Create TempDir temp_ca_dir = tempfile.mkdtemp() except OSError, e: raise RuntimeError("Creating temporary directory failed: %s" % str(e)) try: run(["/usr/bin/wget", "-O", "%s/ca.crt" % temp_ca_dir, "http://%s/ipa/config/ca.crt" % thost]) except CalledProcessError, e: logging.debug('Retrieving CA from %s failed.\n%s' % (thost, str(e))) return [NOT_IPA_SERVER] #now verify the server is really an IPA server try: logging.debug("Init ldap with: ldap://"+thost+":389") lh = ldap.initialize("ldap://"+thost+":389") ldap.set_option(ldap.OPT_X_TLS_REQUIRE_CERT, True) ldap.set_option(ldap.OPT_X_TLS_CACERTFILE, "%s/ca.crt" % temp_ca_dir) lh.set_option(ldap.OPT_PROTOCOL_VERSION, 3) lh.set_option(ldap.OPT_X_TLS_DEMAND, True) lh.start_tls_s() lh.simple_bind_s("","") # get IPA base DN logging.debug("Search LDAP server for IPA base DN") basedn = get_ipa_basedn(lh) if basedn is None: return [NOT_IPA_SERVER] self.basedn = basedn #search and return known realms logging.debug("Search for (objectClass=krbRealmContainer) in "+self.basedn+"(sub)") lret = lh.search_s("cn=kerberos,"+self.basedn, ldap.SCOPE_SUBTREE, "(objectClass=krbRealmContainer)") if not lret: #something very wrong return [REALM_NOT_FOUND] logging.debug("Found: "+str(lret)) for lres in lret: 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): logging.error("LDAP Error: timeout") return [NO_LDAP_SERVER] if isinstance(err, ldap.INAPPROPRIATE_AUTH): logging.debug("LDAP Error: Anonymous acces not allowed") return [NO_ACCESS_TO_LDAP] logging.error("LDAP Error: %s: %s" % (err.args[0]['desc'], err.args[0].get('info', ''))) return [UNKNOWN_ERROR] finally: os.remove("%s/ca.crt" % temp_ca_dir) os.rmdir(temp_ca_dir) def ipadnssearchldap(self, tdomain): servers = "" rserver = "" qname = "_ldap._tcp."+tdomain # terminate the name if not qname.endswith("."): qname += "." results = ipapython.dnsclient.query(qname, ipapython.dnsclient.DNS_C_IN, ipapython.dnsclient.DNS_T_SRV) for result in results: if result.dns_type == ipapython.dnsclient.DNS_T_SRV: rserver = result.rdata.server.rstrip(".") if result.rdata.port and result.rdata.port != 389: rserver += ":" + str(result.rdata.port) if servers: servers += "," + rserver else: servers = rserver break return servers def ipadnssearchkrb(self, tdomain): realm = None kdc = None # now, check for a Kerberos realm the local host or domain is in qname = "_kerberos." + tdomain # terminate the name if not qname.endswith("."): qname += "." results = ipapython.dnsclient.query(qname, ipapython.dnsclient.DNS_C_IN, ipapython.dnsclient.DNS_T_TXT) for result in results: if result.dns_type == ipapython.dnsclient.DNS_T_TXT: realm = result.rdata.data if realm: break if realm: # now fetch server information for the realm qname = "_kerberos._udp." + realm.lower() # terminate the name if not qname.endswith("."): qname += "." results = ipapython.dnsclient.query(qname, ipapython.dnsclient.DNS_C_IN, ipapython.dnsclient.DNS_T_SRV) for result in results: if result.dns_type == ipapython.dnsclient.DNS_T_SRV: qname = result.rdata.server.rstrip(".") if result.rdata.port and result.rdata.port != 88: qname += ":" + str(result.rdata.port) if kdc: kdc += "," + qname else: kdc = qname if not kdc: logging.debug("SRV record for KDC not found! Realm: %s, SRV record: %s" % (realm, qname)) return [realm, kdc]