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/*
*----------------------------------------------------------------------------
*
* msktconf.cpp
*
* (C) 2004-2006 Dan Perry (dperry@pppl.gov)
* (C) 2006 Brian Elliott Finley (finley@anl.gov)
* (C) 2009-2010 Doug Engert (deengert@anl.gov)
* (C) 2010 James Y Knight (foom@fuhm.net)
*
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 2 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, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*
*-----------------------------------------------------------------------------
*/
#include "msktutil.h"
#include <fstream>
std::string create_default_machine_password(const std::string &samaccountname)
{
std::string machine_password(samaccountname);
/* Default machine password after 'reset account' is created with the
* following algorithm:
*
* 1) Remove trailing $ from sAMAcountName
* 2) Truncate to first 14 characters
* 3) Convert all characters to lowercase
*
*/
// Remove trailing '$'
if ( machine_password[machine_password.size() - 1] == '$' )
{
machine_password.resize(machine_password.size() - 1);
}
// Truncate to first 14 characters
if ( machine_password.size() > MAX_DEF_MACH_PASS_LEN )
{
machine_password.resize(MAX_DEF_MACH_PASS_LEN);
}
// Convert all characters to lowercase
for ( size_t i = 0; i < machine_password.size(); i++ )
{
machine_password[i] = std::tolower(machine_password[i]);
}
VERBOSE("Default machine password for %s is %s", samaccountname.c_str(), machine_password.c_str());
return machine_password;
}
/* Filenames to delete on exit (temporary config / ccaches) */
static std::string g_config_filename;
static std::string g_ccache_filename;
std::string get_tempfile_name(const char *name) {
std::string full_template = sform("%s/%s-XXXXXX", TMP_DIR, name);
char template_arr[full_template.size() + 1];
memcpy(template_arr, full_template.c_str(), full_template.size() + 1);
int fd = mkstemp(template_arr);
if (fd < 0)
throw Exception(sform("Error: mkstemp failed: %d", errno));
// Didn't need an fd, just to have the filename created securely.
close(fd);
return std::string(template_arr);
}
void create_fake_krb5_conf(msktutil_flags *flags)
{
g_config_filename = get_tempfile_name(".msktkrb5.conf");
std::ofstream file(g_config_filename.c_str());
file << "[libdefaults]\n"
<< " default_realm = " << flags->realm_name << "\n"
<< " dns_lookup_kdc = false\n"
<< " udp_preference_limit = 1\n";
if (flags->allow_weak_crypto) {
file << " allow_weak_crypto = true\n";
}
if (flags->enctypes == VALUE_ON) {
file << " default_tkt_enctypes =";
if (flags->supportedEncryptionTypes & 0x1)
file << " des-cbc-crc";
if (flags->supportedEncryptionTypes & 0x2)
file << " des-cbc-md5";
if (flags->supportedEncryptionTypes & 0x4)
file << " arcfour-hmac-md5";
if (flags->supportedEncryptionTypes & 0x8)
file << " aes128-cts";
if (flags->supportedEncryptionTypes & 0x10)
file << " aes256-cts";
file << "\n";
}
if (flags->no_reverse_lookups)
file << " rdns = false\n";
file << "[realms]\n"
<< " " << flags->realm_name << " = {\n"
<< " kdc = " << flags->server << "\n"
<< " admin_server = " << flags->server << "\n"
<< " }\n";
file.close();
#ifdef HAVE_SETENV
int ret = setenv("KRB5_CONFIG", g_config_filename.c_str(), 1);
if (ret)
throw Exception("setenv failed");
#else
int ret = putenv( strdup((std::string("KRB5_CONFIG=") + g_config_filename).c_str()));
if (ret)
throw Exception("putenv failed");
#endif
VERBOSE("Created a fake krb5.conf file: %s", g_config_filename.c_str());
g_context.reload();
}
void remove_fake_krb5_conf()
{
if (!g_config_filename.empty()) {
unlink(g_config_filename.c_str());
g_config_filename.clear();
}
}
void remove_ccache() {
if (!g_ccache_filename.empty()) {
unlink(g_ccache_filename.c_str());
g_ccache_filename.clear();
}
}
void switch_default_ccache(const char *ccache_name)
{
VERBOSE("Using the local credential cache: %s", ccache_name);
// Is this setenv really necessary given krb5_cc_set_default_name?
// ...answer: YES, because ldap's sasl won't be using our context object,
// and may in fact be using a different implementation of kerberos entirely!
#ifdef HAVE_SETENV
if (setenv("KRB5CCNAME", ccache_name, 1))
throw Exception("Error: setenv failed");
#else
if (!putenv( strdup((std::string("KRB5CCNAME=")+ ccache_name).c_str())))
throw Exception("Error: putenv failed");
#endif
krb5_cc_set_default_name(g_context.get(), ccache_name);
}
bool try_machine_keytab_princ(msktutil_flags *flags, const std::string &principal_name,
const char *ccache_name) {
try {
VERBOSE("Trying to authenticate for %s from local keytab...", principal_name.c_str());
KRB5Keytab keytab(flags->keytab_readname);
KRB5Principal principal(principal_name);
KRB5Creds creds(principal, keytab);
KRB5CCache ccache(ccache_name);
ccache.initialize(principal);
ccache.store(creds);
switch_default_ccache(ccache_name);
return true;
} catch (KRB5Exception &e) {
VERBOSE("%s", e.what());
VERBOSE("Authentication with keytab failed");
return false;
}
}
bool try_machine_password(msktutil_flags *flags, const char *ccache_name) {
try {
VERBOSE("Trying to authenticate for %s with password.", flags->samAccountName.c_str());
KRB5Principal principal(flags->samAccountName);
KRB5Creds creds(principal, /*password:*/ create_default_machine_password(flags->samAccountName));
KRB5CCache ccache(ccache_name);
ccache.initialize(principal);
ccache.store(creds);
switch_default_ccache(ccache_name);
return true;
} catch (KRB5Exception &e) {
VERBOSE("%s", e.what());
VERBOSE("Authentication with password failed");
return false;
}
}
bool try_machine_supplied_password(msktutil_flags *flags, const char *ccache_name) {
try {
VERBOSE("Trying to authenticate for %s with supplied password.", flags->samAccountName.c_str());
KRB5Principal principal(flags->samAccountName);
KRB5Creds creds(principal, /*password:*/ flags->old_account_password);
KRB5CCache ccache(ccache_name);
ccache.initialize(principal);
ccache.store(creds);
switch_default_ccache(ccache_name);
return true;
} catch (KRB5Exception &e) {
VERBOSE("%s", e.what());
if (e.err() == KRB5KDC_ERR_KEY_EXP) {
VERBOSE("Password needs to be changed");
flags->password_expired = true;
return false;
} else {
VERBOSE("Authentication with supplied password failed");
return false;
}
}
}
bool get_creds(msktutil_flags *flags) {
g_ccache_filename = get_tempfile_name(".mskt_krb5_ccache");
std::string ccache_name = "FILE:" + g_ccache_filename;
try {
KRB5Principal principal(flags->samAccountName);
KRB5Creds creds(principal, /*password:*/ flags->password);
KRB5CCache ccache(ccache_name.c_str());
ccache.initialize(principal);
ccache.store(creds);
switch_default_ccache(ccache_name.c_str());
return true;
} catch (KRB5Exception &e) {
VERBOSE("%s", e.what());
VERBOSE("Authentication with password failed");
return false;
}
}
bool try_user_creds() {
try {
VERBOSE("Checking if default ticket cache has tickets...");
// The following is for the side effect of throwing an exception or not.
KRB5CCache ccache(KRB5CCache::defaultName());
KRB5Principal princ(ccache);
return true;
} catch(KRB5Exception &e) {
VERBOSE("%s", e.what());
VERBOSE("User ticket cache was not valid.");
return false;
}
}
int find_working_creds(msktutil_flags *flags) {
/* We try some different ways, in order:
1) Use principal from keytab. Try both:
a) samAccountName
b) host/full-hostname (for compat with older msktutil which didn't write the first).
2) Use principal samAccountName with default password (samAccountName_nodollar)
3) Use supplied credentials (--old-account-password)
When the supplied password has expired (e.g. because the service account
has been newly created) we cannot find any working credentials here
and have to return AUTH_FROM_SUPPLIED_EXPIRED_PASSWORD.
In this case working credentials need to be obtained after changing password
4) Calling user's existing credentials from their credential cache.
*/
if (!flags->user_creds_only) {
std::string host_princ = "host/" + flags->hostname;
// NOTE: we have to use an actual file for the credential cache, and not a MEMORY: type,
// because libsasl may be using heimdal, while this program may be compiled against MIT
// kerberos. So, while it's all in the same process and you'd think an in-mem ccache would
// be the right thing, the two kerberos implementations cannot share an in-memory ccache, so
// we have to use a file. Sigh.
g_ccache_filename = get_tempfile_name(".mskt_krb5_ccache");
std::string ccache_name = "FILE:" + g_ccache_filename;
if (!flags->keytab_auth_princ.empty() && try_machine_keytab_princ(flags, flags->keytab_auth_princ, ccache_name.c_str()))
return AUTH_FROM_EXPLICIT_KEYTAB;
if (try_machine_keytab_princ(flags, flags->samAccountName, ccache_name.c_str()))
return AUTH_FROM_SAM_KEYTAB;
if (try_machine_keytab_princ(flags, host_princ, ccache_name.c_str()))
return AUTH_FROM_HOSTNAME_KEYTAB;
if (try_machine_password(flags, ccache_name.c_str()))
return AUTH_FROM_PASSWORD;
if (strlen(flags->old_account_password.c_str())) {
if (try_machine_supplied_password(flags, ccache_name.c_str())) {
return AUTH_FROM_SUPPLIED_PASSWORD;
}
if (flags->password_expired) {
return AUTH_FROM_SUPPLIED_EXPIRED_PASSWORD;
}
}
}
if (try_user_creds())
return AUTH_FROM_USER_CREDS;
return AUTH_NONE;
}
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