path: root/install/tools/ipa-fix-CVE-2008-3274

#!/usr/bin/python
#
# Upgrade configuration files to a newer template.

etckrb5conf = "/etc/krb5.conf"
krb5dir = "/var/kerberos/krb5kdc"
cachedir = "/var/cache/ipa"
libdir = "/var/lib/ipa"
basedir = libdir+"/mkey"
ourkrb5conf = basedir+"/krb5.conf"
ldappwdfile = basedir+"/ldappwd"

import sys
try:
    from optparse import OptionParser

    import os
    import random
    import time
    import shutil
    import getpass

    import ipa
    import ipapython.config
    import ipapython.ipautil

    import krbV

    from ipalib import errors
    from ipaclient import ipachangeconf
    from ipaserver.plugins.ldap2 import ldap2

    from pyasn1.type import univ, namedtype
    import pyasn1.codec.ber.encoder
    import pyasn1.codec.ber.decoder
    import struct
    import base64

except ImportError:
    print >> sys.stderr, """\
There was a problem importing one of the required Python modules. The
error was:

    %s
""" % sys.exc_value
    sys.exit(1)

def parse_options():
    parser = OptionParser("%prog [--check] [--fix] [--fix-replica]")
    parser.add_option("--check", dest="check", action="store_true",
                      help="Just check for the vulnerability and report (default action)")
    parser.add_option("--fix", dest="fix", action="store_true",
                      help="Run checks and start procedure to fix the problem")
    parser.add_option("--fix-replica", dest="fix_replica", action="store_true",
                      help="Fix a replica after the tool has been tun with --fix on another master")

    ipapython.config.add_standard_options(parser)
    options, args = parser.parse_args()

    ipapython.config.verify_args(parser, args)
    if not options.fix and not options.fix_replica and not options.check:
        parser.error("please specify at least one option")

    ipapython.config.init_config(options)

    return options, args

def check_vuln(realm, suffix):

    ldapuri = 'ldap://127.0.0.1'
    try:
        conn = ldap2(shared_instance=False, ldap_uri=ldapuri, base_dn=suffix)
        conn.connect()
        try:
            (entries, truncated) = conn.find_entries(
                filter='(objectclass=krbRealmContainer)',
                attrs_list=('krbmkey', 'cn'), scope=ldap2.SCOPE_BASE,
                base_dn='cn=%s,cn=kerberos' % realm
            )
        except errors.NotFound:
            err = 'Realm Container not found, unable to proceed'
            print err
            raise Exception, err
        finally:
            conn.disconnect()

        if 'krbmkey' in entries[0][1]:
            print 'System vulnerable'
            return 1
        else:
            print 'System *not* vulnerable'
            return 0
    except Exception, e:
        print "Could not connect to the LDAP server, unable to check server"
        print "("+type(e)+")("+dir(e)+")"
        raise e

# We support only des3 encoded stash files for now
def generate_new_stash_file(file):

    odd_parity_bytes_pool = ['\x01', '\x02', '\x04', '\x07', '\x08', '\x0b',
        '\r', '\x0e', '\x10', '\x13', '\x15', '\x16', '\x19', '\x1a', '\x1c',
        '\x1f', ' ', '#', '%', '&', ')', '*', ',', '/', '1', '2', '4', '7', '8',
        ';', '=', '>', '@', 'C', 'E', 'F', 'I', 'J', 'L', 'O', 'Q', 'R', 'T',
        'W', 'X', '[', ']', '^', 'a', 'b', 'd', 'g', 'h', 'k', 'm', 'n', 'p',
        's', 'u', 'v', 'y', 'z', '|', '\x7f', '\x80', '\x83', '\x85', '\x86',
        '\x89', '\x8a', '\x8c', '\x8f', '\x91', '\x92', '\x94', '\x97', '\x98',
        '\x9b', '\x9d', '\x9e', '\xa1', '\xa2', '\xa4', '\xa7', '\xa8', '\xab',
        '\xad', '\xae', '\xb0', '\xb3', '\xb5', '\xb6', '\xb9', '\xba', '\xbc',
        '\xbf', '\xc1', '\xc2', '\xc4', '\xc7', '\xc8', '\xcb', '\xcd', '\xce',
        '\xd0', '\xd3', '\xd5', '\xd6', '\xd9', '\xda', '\xdc', '\xdf', '\xe0',
        '\xe3', '\xe5', '\xe6', '\xe9', '\xea', '\xec', '\xef', '\xf1', '\xf2',
        '\xf4', '\xf7', '\xf8', '\xfb', '\xfd', '\xfe']

    pool_len = len(odd_parity_bytes_pool)
    keytype = 16 # des3
    keydata = ""

    r = random.SystemRandom()
    for k in range(24):
        keydata += r.choice(odd_parity_bytes_pool)

    format = '=hi%ss' % len(keydata)
    s = struct.pack(format, keytype, len(keydata), keydata)
    try:
        fd = open(file, "w")
        fd.write(s)
    except os.error, e:
        logging.critical("failed to write stash file")
        raise e

# clean up procedures
def change_mkey_cleanup(password):
    try:
        os.stat(basedir)
    except:
        return None
    try:
        # always remove ldappwdfile as it contains the Directory Manager password
        os.remove(ldappwdfile)
    except:
        pass

    # tar and encrypt the working dir so that we do not leave sensitive data
    # around unproteceted
    curtime = time.strftime("%Y%m%d%H%M%S",time.gmtime())
    tarfile = libdir+"/ipa-change-mkey-"+curtime+".tar"
    gpgfile = tarfile+".gpg"
    args = ['/bin/tar', '-C', libdir, '-cf', tarfile, 'mkey']
    ipapython.ipautil.run(args)
    ipapython.ipautil.encrypt_file(tarfile, gpgfile, password, cachedir)
    os.remove(tarfile)
    shutil.rmtree(basedir, ignore_errors=True)

    return "The temporary working directory with backup dump files has been securely archived and gpg-encrypted as "+gpgfile+" using the Directory Manager password."

def change_mkey(password = None, quiet = False):

    krbctx = krbV.default_context()

    realm = krbctx.default_realm
    suffix = ipapython.ipautil.realm_to_suffix(realm)

    backupfile = basedir+"/backup.dump"
    convertfile = basedir+"/convert.dump"
    oldstashfile = krb5dir+"/.k5."+realm
    newstashfile = basedir+"/.new.mkey"
    bkpstashfile = basedir+"/.k5."+realm

    if os.getuid() != 0:
        print "ERROR: This command must be run as root"
        sys.exit(1)

    print "DANGER: This is a dangerous operation, make sure you backup all your IPA data before running the tool"
    print "This command will restart your Directory and KDC Servers."

    #TODO: ask for confirmation
    if not ipapython.ipautil.user_input("Do you want to proceed and change the Kerberos Master key?", False):
        print ""
        print "Aborting..."
        return 1

    if not password:
        password = getpass.getpass("Directory Manager password: ")

    # get a connection to the DS
    ldapuri = 'ldap://%s' % ipapython.config.config.default_server[0]
    try:
        conn = ldap2(shared_instance=False, ldap_uri=ldapuri, base_dn=suffix)
        conn.connect(bind_dn='cn=directory manager', bind_pw=password)
    except Exception, e:
        print "ERROR: Could not connect to the Directory Server on "+ipapython.config.config.default_server[0]+" ("+str(e)+")"
        return 1

    #  Wipe basedir and recreate it
    shutil.rmtree(basedir, ignore_errors=True)
    os.mkdir(basedir, 0700)

    generate_new_stash_file(newstashfile)

    # Generate conf files
    try:
        shutil.copyfile(etckrb5conf, ourkrb5conf)

        krbconf = ipachangeconf.IPAChangeConf("IPA Installer")
        krbconf.setOptionAssignment(" = ")
        krbconf.setSectionNameDelimiters(("[","]"))
        krbconf.setSubSectionDelimiters(("{","}"))
        krbconf.setIndent(("","  ","    "))

        #OPTS
        opts = [{'name':'ldap_kadmind_dn', 'type':'option', 'action':'set', 'value':'cn=Directory Manager'},
                {'name':'ldap_service_password_file', 'type':'option', 'action':'set', 'value':ldappwdfile}]

        #REALM
        realmopts = [{'name':realm, 'type':'subsection', 'action':'set', 'value':opts}]

        #DBMODULES
        dbopts = [{'name':'dbmodules', 'type':'section', 'action':'set', 'value':realmopts}]

        krbconf.changeConf(ourkrb5conf, dbopts);

        hexpwd = ""
        for x in password:
            hexpwd += (hex(ord(x))[2:])
        pwd_fd = open(ldappwdfile, "w")
        pwd_fd.write("cn=Directory Manager#{HEX}"+hexpwd+"\n")
        pwd_fd.close()
        os.chmod(ldappwdfile, 0600)

    except Exception, e:
        print "Failed to create custom configuration files ("+str(e)+") aborting..."
        return 1

    #Set environment vars so that the modified krb5.conf is used
    os.environ['KRB5_CONFIG'] = ourkrb5conf

    #Backup the kerberos key material for recovery if needed
    args = ["/usr/kerberos/sbin/kdb5_util", "dump", "-verbose", backupfile]
    print "Performing safety backup of the key material"
    try:
        output = ipapython.ipautil.run(args)
    except ipapython.ipautil.CalledProcessError, e:
        print "Failed to backup key material ("+str(e)+"), aborting ..."
        return 1

    if not quiet:
        princlist = output[1].split('\n')
        print "Principals stored into the backup file "+backupfile+":"
        for p in princlist:
            print p
        print ""

    #Convert the kerberos keys to the new master key
    args = ["/usr/kerberos/sbin/kdb5_util", "dump", "-verbose", "-new_mkey_file", newstashfile, convertfile]
    print "Converting key material to new master key"
    try:
        output = ipapython.ipautil.run(args)
    except ipapython.ipautil.CalledProcessError, e:
        print "Failed to convert key material, aborting ..."
        return 1

    savedprinclist = output[1].split('\n')

    if not quiet:
        princlist = output[1].split('\n')
        print "Principals dumped for conversion:"
        for p in princlist:
            print p
        print ""

    #Stop the KDC
    args = ["/etc/init.d/krb5kdc", "stop"]
    try:
        output = ipapython.ipautil.run(args)
        if output[0]:
            print output[0]
        if output[1]:
            print output[1]
    except ipapython.ipautil.CalledProcessError, e:
        print "WARNING: Failed to restart the KDC ("+str(e)+")"
        print "You will have to manually restart the KDC when the operation is completed"

    #Change the mkey into ldap
    try:
        stash = open(newstashfile, "r")
        keytype = struct.unpack('h', stash.read(2))[0]
        keylen = struct.unpack('i', stash.read(4))[0]
        keydata = stash.read(keylen)

        #encode it in the asn.1 attribute
        MasterKey = univ.Sequence()
        MasterKey.setComponentByPosition(0, univ.Integer(keytype))
        MasterKey.setComponentByPosition(1, univ.OctetString(keydata))
        krbMKey = univ.Sequence()
        krbMKey.setComponentByPosition(0, univ.Integer(0)) #we have no kvno
        krbMKey.setComponentByPosition(1, MasterKey)
        asn1key = pyasn1.codec.ber.encoder.encode(krbMKey)

        dn = "cn="+realm+",cn=kerberos,"+suffix
        mod = {'krbmkey': str(asn1key)}
        conn.update_entry(dn, mod)
    except Exception, e:
        print "ERROR: Failed to upload the Master Key from the Stash file: "+newstashfile+" ("+str(e)+")"
        return 1

    #Backup old stash file and substitute with new
    try:
        shutil.move(oldstashfile, bkpstashfile)
        shutil.copyfile(newstashfile, oldstashfile)
    except Exception, e:
        print "ERROR: An error occurred while installing the new stash file("+str(e)+")"
        print "The KDC may fail to start if the correct stash file is not in place"
        print "Verify that "+newstashfile+" has been correctly installed into "+oldstashfile
        print "A backup copy of the old stash file should be saved in "+bkpstashfile

    #Finally upload the converted principals
    args = ["/usr/kerberos/sbin/kdb5_util", "load", "-verbose", "-update", convertfile]
    print "Uploading converted key material"
    try:
        output = ipapython.ipautil.run(args)
    except ipapython.ipautil.CalledProcessError, e:
        print "Failed to upload key material ("+e+"), aborting ..."
        return 1

    if not quiet:
        princlist = output[1].split('\n')
        print "Principals converted and uploaded:"
        for p in princlist:
            print p
        print ""

    uploadedprinclist = output[1].split('\n')

    #Check for differences and report
    d = []
    for p in savedprinclist:
        if uploadedprinclist.count(p) == 0:
            d.append(p)
    if len(d) != 0:
        print "WARNING: Not all dumped principals have been updated"
        print "Principals not Updated:"
        for p in d:
            print p

    #Remove custom environ
    del os.environ['KRB5_CONFIG']

    #Restart Directory Server (the pwd plugin need to read the new mkey)
    args = ["/etc/init.d/dirsrv", "restart"]
    try:
        output = ipapython.ipautil.run(args)
        if output[0]:
            print output[0]
        if output[1]:
            print output[1]
    except ipapython.ipautil.CalledProcessError, e:
        print "WARNING: Failed to restart the Directory Server ("+str(e)+")"
        print "Please manually restart the DS with 'service dirsrv restart'"

    #Restart the KDC
    args = ["/etc/init.d/krb5kdc", "start"]
    try:
        output = ipapython.ipautil.run(args)
        if output[0]:
            print output[0]
        if output[1]:
            print output[1]
    except ipapython.ipautil.CalledProcessError, e:
        print "WARNING: Failed to restart the KDC ("+str(e)+")"
        print "Please manually restart the kdc with 'service krb5kdc start'"

    print "Master Password successfully changed"
    #print "You MUST now copy the stash file "+oldstashfile+" to all the replicas and restart them!"
    print ""

    return 0

def fix_replica(password, realm, suffix):

    try:
        conn = ldapobject.SimpleLDAPObject("ldap://127.0.0.1/")
        conn.simple_bind("cn=Directory Manager", password)
        msgid = conn.search("cn="+realm+",cn=kerberos,"+suffix,
                            ldap.SCOPE_BASE,
                            "(objectclass=krbRealmContainer)",
                            ("krbmkey", "cn"))
        res = conn.result(msgid)
        conn.unbind()
        krbmkey = res[1][0][1]['krbmkey'][0]
    except Exception, e:
        print "Could not connect to the LDAP server, unable to fix server"
        print "("+type(e)+")("+dir(e)+")"
        raise e

    krbMKey = pyasn1.codec.ber.decoder.decode(krbmkey)
    keytype = int(krbMKey[0][1][0])
    keydata = str(krbMKey[0][1][1])

    format = '=hi%ss' % len(keydata)
    s = struct.pack(format, keytype, len(keydata), keydata)
    try:
        fd = open("/var/kerberos/krb5kdc/.k5."+realm, "w")
        fd.write(s)
        fd.close()
    except os.error, e:
        print "failed to write stash file"
        raise e

    #restart KDC so that it can reload the new Master Key
    os.system("/etc/init.d/krb5kdc restart")

KRBMKEY_DENY_ACI = """
(targetattr = "krbMKey")(version 3.0; acl "No external access"; deny (all) userdn != "ldap:///uid=kdc,cn=sysaccounts,cn=etc,$SUFFIX";)
"""

def fix_main(password, realm, suffix):

    #Run the change master key tool
    print "Changing Kerberos master key"
    try:
        ret = change_mkey(password, True)
    except SystemExit:
        ret = 1
        pass
    except Exception, e:
        ret = 1
        print "%s" % str(e)

    try:
        msg = change_mkey_cleanup(password)
        if msg:
            print msg
    except Exception, e:
        print "Failed to clean up the temporary location for the dump files and generate and encrypted archive with error:"
        print e
        print "Please securely archive/encrypt "+basedir

    if ret is not 0:
        sys.exit(ret)

    #Finally upload new master key

    #get the Master Key from the stash file
    try:
        stash = open("/var/kerberos/krb5kdc/.k5."+realm, "r")
        keytype = struct.unpack('h', stash.read(2))[0]
        keylen = struct.unpack('i', stash.read(4))[0]
        keydata = stash.read(keylen)
    except os.error:
        print "Failed to retrieve Master Key from Stash file: %s"
        raise e
    #encode it in the asn.1 attribute
    MasterKey = univ.Sequence()
    MasterKey.setComponentByPosition(0, univ.Integer(keytype))
    MasterKey.setComponentByPosition(1, univ.OctetString(keydata))
    krbMKey = univ.Sequence()
    krbMKey.setComponentByPosition(0, univ.Integer(0)) #we have no kvno
    krbMKey.setComponentByPosition(1, MasterKey)
    asn1key = pyasn1.codec.ber.encoder.encode(krbMKey)

    dn = 'cn=%s,cn=kerberos' % realm
    sub_dict = dict(REALM=realm, SUFFIX=suffix)
    #protect the master key by adding an appropriate deny rule along with the key
    conn = ldap2(
        shared_instance=False, ldap_uri='ldap://127.0.0.1',
        base_dn=suffix
    )
    conn.connect(bind_dn='cn=directory manager', bind_pw=password)

    (dn, entry_attrs) = conn.get_entry(dn, ['aci'])

    entry_attrs['krbmkey'] = str(asn1key)
    entry_attrs.setdefault('aci', []).append(
        ipapython.ipautil.template_str(KRBMKEY_DENY_ACI, sub_dict)
    )

    conn.update_entry(dn, entry_attrs)

    conn.disconnect()

    print "\n"
    print "This server is now correctly configured and the master-key has been changed and secured."
    print "Please now run this tool with the --fix-replica option on all your other replicas."
    print "Until you fix the replicas their KDCs will not work."

def main():

    options, args = parse_options()

    if options.fix or options.fix_replica:
        password = getpass.getpass("Directory Manager password: ")

    krbctx = krbV.default_context()
    realm = krbctx.default_realm
    suffix = ipapython.ipautil.realm_to_suffix(realm)

    try:
        ret = check_vuln(realm, suffix)
    except:
        sys.exit(1)

    if options.fix_replica:
        if ret is 1:
            print "Your system is still vulnerable"
            print "If you have already run this tool with --fix on a master then make sure your replication is working correctly, before runnig --fix-replica"
            sys.exit(1)
        try:
            fix_replica(password, realm, suffix)
        except Exception, e:
            print "Unexpected error ("+str(e)+")"
            sys.exit(1)
        sys.exit(0)

    if options.check:
        sys.exit(0)

    if options.fix:
        if ret is 1:
            try:
                ret = fix_main(password, realm, suffix)
            except Exception, e:
                print "Unexpected error ("+str(e)+")"
                sys.exit(1)
        sys.exit(ret)

try:
    if __name__ == "__main__":
        sys.exit(main())
except SystemExit, e:
    sys.exit(e)
except KeyboardInterrupt, e:
    sys.exit(1)