# 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 from ipapython.ipa_log_manager import * import tempfile import ldap from ldap import LDAPError from dns import resolver, rdatatype from dns.exception import DNSException from ipapython.ipautil import run, CalledProcessError, valid_ip, get_ipa_basedn, \ realm_to_suffix, format_netloc 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 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', 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.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 (server, domain) or (None,None) if a SRV record isn't found. :param tried: A set of domains that were tried already :param reason: Reason this domain is searched (included in the log) """ server = None root_logger.debug('Start searching for LDAP SRV record in "%s" (%s) ' + 'and its sub-domains', domain, reason) while not server: if domain in tried: root_logger.debug("Already searched %s; skipping", domain) break tried.add(domain) server = self.ipadns_search_srv(domain, '_ldap._tcp', 389) if server: return (server[0], 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): root_logger.debug("[IPA Discovery]") root_logger.debug( 'Starting IPA discovery with domain=%s, server=%s, hostname=%s', domain, server, hostname) if type(server) in (list, tuple): server = server[0] if not server: 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: server, domain = self.check_domain(domain, tried, reason) if server: self.server = server 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) server = self.ipadns_search_srv(domain, '_ldap._tcp', 389) if server: self.server = server[0] 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.server = server self.domain_source = self.server_source = 'Forced' #search for kerberos root_logger.debug("[Kerberos realm search]") krb_realm, kdc = self.ipadnssearchkrb(self.domain) if not server and not krb_realm: return REALM_NOT_FOUND self.realm = krb_realm self.kdc = kdc self.realm_source = self.kdc_source = ( 'Discovered Kerberos DNS records from %s' % self.domain) root_logger.debug("[LDAP server check]") root_logger.debug('Verifying that %s (realm %s) is an IPA server', self.server, self.realm) # 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 if self.server: # check ldap now ldapret = self.ipacheckldap(self.server, self.realm) 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) elif ldapret[0] == NO_ACCESS_TO_LDAP: ldapaccess = False # 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) 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 disabled) 2 means the server is certainly not an IPA server """ 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, "-T", "15", "-t", "2", "http://%s/ipa/config/ca.crt" % format_netloc(thost)]) except CalledProcessError, e: root_logger.debug('Retrieving CA from %s failed: %s', thost, str(e)) return [NOT_IPA_SERVER] #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) 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 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("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.error("LDAP Error: timeout") return [NO_LDAP_SERVER] if isinstance(err, ldap.INAPPROPRIATE_AUTH): root_logger.debug("LDAP Error: Anonymous acces not allowed") return [NO_ACCESS_TO_LDAP] root_logger.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 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) root_logger.debug("Search DNS for SRV record of %s", qname) try: answers = resolver.query(qname, rdatatype.SRV) except DNSException, e: root_logger.debug("DNS record not found: %s", e.__class__.__name__) answers = [] for answer in answers: root_logger.debug("DNS record found: %s", answer) server = str(answer.target).rstrip(".") if not server: root_logger.debug("Cannot parse the hostname from SRV record: %s", answer) continue if default_port is not None and answer.port != default_port: server = "%s:%s" % (server, str(answer.port)) servers.append(server) if break_on_first: 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 root_logger.debug("Search DNS for TXT record of %s", qname) try: answers = resolver.query(qname, rdatatype.TXT) except DNSException, e: root_logger.debug("DNS record not found: %s", e.__class__.__name__) answers = [] for answer in answers: root_logger.debug("DNS record found: %s", answer) if answer.strings: realm = answer.strings[0] if realm: break if realm: # now fetch server information for the realm domain = realm.lower() kdc = self.ipadns_search_srv(domain, '_kerberos._udp', 88, break_on_first=False) if not kdc: root_logger.debug("SRV record for KDC not found! Realm: %s, SRV record: %s" % (realm, qname)) kdc = None kdc = ','.join(kdc) return realm, kdc