mirror of
https://salsa.debian.org/freeipa-team/freeipa.git
synced 2025-01-12 17:21:55 -06:00
f90e137a17
On multiple occasions, SRV query answers were not properly sorted by priority. Records with same priority weren't randomized and shuffled. This caused FreeIPA to contact the same remote peer instead of distributing the load across all available servers. Two new helper functions now take care of SRV queries. sort_prio_weight() sorts SRV and URI records. query_srv() combines SRV lookup with sort_prio_weight(). Fixes: https://pagure.io/freeipa/issue/7475 Signed-off-by: Christian Heimes <cheimes@redhat.com> Reviewed-By: Rob Crittenden <rcritten@redhat.com>
569 lines
21 KiB
Python
569 lines
21 KiB
Python
# 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/>.
|
|
#
|
|
|
|
from __future__ import absolute_import
|
|
|
|
import logging
|
|
import socket
|
|
|
|
import six
|
|
|
|
from dns import resolver, rdatatype
|
|
from dns.exception import DNSException
|
|
from ipalib import errors
|
|
from ipapython.dnsutil import query_srv
|
|
from ipapython import ipaldap
|
|
from ipaplatform.paths import paths
|
|
from ipapython.ipautil import valid_ip, realm_to_suffix
|
|
from ipapython.dn import DN
|
|
|
|
logger = logging.getLogger(__name__)
|
|
|
|
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
|
|
|
|
IPA_BASEDN_INFO = 'ipa v2.0'
|
|
|
|
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',
|
|
}
|
|
|
|
def get_ipa_basedn(conn):
|
|
"""
|
|
Get base DN of IPA suffix in given LDAP server.
|
|
|
|
None is returned if the suffix is not found
|
|
|
|
:param conn: Bound LDAPClient that will be used for searching
|
|
"""
|
|
entry = conn.get_entry(
|
|
DN(), attrs_list=['defaultnamingcontext', 'namingcontexts'])
|
|
|
|
contexts = [c.decode('utf-8') for c in entry.raw['namingcontexts']]
|
|
if 'defaultnamingcontext' in entry:
|
|
# If there is a defaultNamingContext examine that one first
|
|
[default] = entry.raw['defaultnamingcontext']
|
|
default = default.decode('utf-8')
|
|
if default in contexts:
|
|
contexts.remove(default)
|
|
contexts.insert(0, default)
|
|
for context in contexts:
|
|
logger.debug("Check if naming context '%s' is for IPA", context)
|
|
try:
|
|
[entry] = conn.get_entries(
|
|
DN(context), conn.SCOPE_BASE, "(info=IPA*)")
|
|
except errors.NotFound:
|
|
logger.debug("LDAP server did not return info attribute to "
|
|
"check for IPA version")
|
|
continue
|
|
[info] = entry.raw['info']
|
|
info = info.decode('utf-8').lower()
|
|
if info != IPA_BASEDN_INFO:
|
|
logger.debug("Detected IPA server version (%s) did not match the "
|
|
"client (%s)",
|
|
info, IPA_BASEDN_INFO)
|
|
continue
|
|
logger.debug("Naming context '%s' is a valid IPA context", context)
|
|
return DN(context)
|
|
|
|
return None
|
|
|
|
|
|
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(paths.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 Exception:
|
|
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
|
|
logger.debug('Start searching for LDAP SRV record in "%s" (%s) '
|
|
'and its sub-domains', domain, reason)
|
|
while not servers:
|
|
if domain in tried:
|
|
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.
|
|
"""
|
|
logger.debug("[IPA Discovery]")
|
|
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()
|
|
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
|
|
logger.debug('No LDAP server found')
|
|
return NO_LDAP_SERVER
|
|
else:
|
|
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
|
|
logger.debug('No LDAP server found')
|
|
return NO_LDAP_SERVER
|
|
|
|
else:
|
|
|
|
logger.debug("Server and domain forced")
|
|
self.domain = domain
|
|
self.domain_source = self.server_source = 'Forced'
|
|
|
|
#search for kerberos
|
|
logger.debug("[Kerberos realm search]")
|
|
if realm:
|
|
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
|
|
|
|
if autodiscovered:
|
|
self.kdc = self.ipadnssearchkrbkdc()
|
|
self.kdc_source = (
|
|
'Discovered Kerberos DNS records from %s' % self.domain)
|
|
else:
|
|
self.kdc = ', '.join(servers)
|
|
self.kdc_source = "Kerberos DNS record discovery bypassed"
|
|
|
|
# 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
|
|
logger.debug("[LDAP server check]")
|
|
valid_servers = []
|
|
for server in servers:
|
|
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.append(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.append(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:
|
|
logger.warning(
|
|
'Skip %s: not an IPA server', server)
|
|
elif ldapret[0] == NO_LDAP_SERVER:
|
|
logger.warning(
|
|
'Skip %s: LDAP server is not responding, unable to verify '
|
|
'if this is an IPA server', server)
|
|
else:
|
|
logger.warning(
|
|
'Skip %s: cannot verify if this is an IPA server', server)
|
|
|
|
# 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'
|
|
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'
|
|
logger.debug("Generated basedn from realm: %s", self.basedn)
|
|
|
|
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)
|
|
|
|
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 = []
|
|
|
|
#now verify the server is really an IPA server
|
|
try:
|
|
ldap_uri = ipaldap.get_ldap_uri(thost)
|
|
start_tls = False
|
|
if ca_cert_path:
|
|
start_tls = True
|
|
logger.debug("Init LDAP connection to: %s", ldap_uri)
|
|
lh = ipaldap.LDAPClient(
|
|
ldap_uri, cacert=ca_cert_path, start_tls=start_tls,
|
|
no_schema=True, decode_attrs=False)
|
|
try:
|
|
lh.simple_bind(DN(), '')
|
|
|
|
# get IPA base DN
|
|
logger.debug("Search LDAP server for IPA base DN")
|
|
basedn = get_ipa_basedn(lh)
|
|
except errors.ACIError:
|
|
logger.debug("LDAP Error: Anonymous access not allowed")
|
|
return [NO_ACCESS_TO_LDAP]
|
|
except errors.DatabaseError as err:
|
|
logger.error("Error checking LDAP: %s", err.strerror)
|
|
# We should only get UNWILLING_TO_PERFORM if the remote LDAP
|
|
# server has minssf > 0 and we have attempted a non-TLS conn.
|
|
if ca_cert_path is None:
|
|
logger.debug(
|
|
"Cannot connect to LDAP server. Check that minssf is "
|
|
"not enabled")
|
|
return [NO_TLS_LDAP]
|
|
else:
|
|
return [UNKNOWN_ERROR]
|
|
|
|
if basedn is None:
|
|
logger.debug("The server is not an IPA server")
|
|
return [NOT_IPA_SERVER]
|
|
|
|
self.basedn = basedn
|
|
self.basedn_source = 'From IPA server %s' % lh.ldap_uri
|
|
|
|
#search and return known realms
|
|
logger.debug(
|
|
"Search for (objectClass=krbRealmContainer) in %s (sub)",
|
|
self.basedn)
|
|
try:
|
|
lret = lh.get_entries(
|
|
DN(('cn', 'kerberos'), self.basedn),
|
|
lh.SCOPE_SUBTREE, "(objectClass=krbRealmContainer)")
|
|
except errors.NotFound:
|
|
#something very wrong
|
|
return [REALM_NOT_FOUND]
|
|
|
|
for lres in lret:
|
|
logger.debug("Found: %s", lres.dn)
|
|
[cn] = lres.raw['cn']
|
|
if six.PY3:
|
|
cn = cn.decode('utf-8')
|
|
lrealms.append(cn)
|
|
|
|
if trealm:
|
|
for r in lrealms:
|
|
if trealm == r:
|
|
return [0, thost, trealm]
|
|
# must match or something is very wrong
|
|
logger.debug("Realm %s does not match any realm in LDAP "
|
|
"database", trealm)
|
|
return [REALM_NOT_FOUND]
|
|
else:
|
|
if len(lrealms) != 1:
|
|
#which one? we can't attach to a multi-realm server without DNS working
|
|
logger.debug("Multiple realms found, cannot decide "
|
|
"which realm is the right without "
|
|
"working DNS")
|
|
return [REALM_NOT_FOUND]
|
|
else:
|
|
return [0, thost, lrealms[0]]
|
|
|
|
#we shouldn't get here
|
|
assert False, "Unknown error in ipadiscovery"
|
|
|
|
except errors.DatabaseTimeout:
|
|
logger.debug("LDAP Error: timeout")
|
|
return [NO_LDAP_SERVER]
|
|
except errors.NetworkError as err:
|
|
logger.debug("LDAP Error: %s", err.strerror)
|
|
return [NO_LDAP_SERVER]
|
|
except errors.ACIError:
|
|
logger.debug("LDAP Error: Anonymous access not allowed")
|
|
return [NO_ACCESS_TO_LDAP]
|
|
except errors.DatabaseError as err:
|
|
logger.debug("Error checking LDAP: %s", err.strerror)
|
|
return [UNKNOWN_ERROR]
|
|
except Exception as err:
|
|
logger.debug("Error checking LDAP: %s", err)
|
|
|
|
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)
|
|
|
|
logger.debug("Search DNS for SRV record of %s", qname)
|
|
|
|
try:
|
|
answers = query_srv(qname)
|
|
except DNSException as e:
|
|
logger.debug("DNS record not found: %s", e.__class__.__name__)
|
|
answers = []
|
|
|
|
for answer in answers:
|
|
logger.debug("DNS record found: %s", answer)
|
|
server = str(answer.target).rstrip(".")
|
|
if not server:
|
|
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 ipadnssearchkrbrealm(self, domain=None):
|
|
"""
|
|
:param domain: Domain to be searched in
|
|
:returns: string of a realm found in a TXT record
|
|
None if no realm was found
|
|
"""
|
|
if not domain:
|
|
domain = self.domain
|
|
# now, check for a Kerberos realm the local host or domain is in
|
|
qname = "_kerberos." + domain
|
|
|
|
logger.debug("Search DNS for TXT record of %s", qname)
|
|
|
|
try:
|
|
answers = resolver.query(qname, rdatatype.TXT)
|
|
except DNSException as e:
|
|
logger.debug("DNS record not found: %s", e.__class__.__name__)
|
|
answers = []
|
|
|
|
realm = None
|
|
for answer in answers:
|
|
logger.debug("DNS record found: %s", answer)
|
|
if answer.strings:
|
|
try:
|
|
realm = answer.strings[0].decode('utf-8')
|
|
except UnicodeDecodeError as e:
|
|
logger.debug(
|
|
'A TXT record cannot be decoded as UTF-8: %s', e)
|
|
continue
|
|
if realm:
|
|
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:
|
|
logger.debug("SRV record for KDC not found! Domain: %s", domain)
|
|
kdc = None
|
|
|
|
return kdc
|