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mirror of https://github.com/samba-team/samba.git synced 2024-12-23 17:34:34 +03:00
samba-mirror/libgpo/pygpo.c
David Mulder ac4726106c gpupdate: Deprecate libgpo.get_gpo_list
This is no longer used by gpupdate.

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15225

Signed-off-by: David Mulder <dmulder@samba.org>
Reviewed-by: Andrew Bartlett <abartlet@samba.org>
2023-04-28 02:15:36 +00:00

763 lines
19 KiB
C

/*
Unix SMB/CIFS implementation.
Copyright (C) Luke Morrison <luc785@hotmail.com> 2013
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/>.
*/
#include <Python.h>
#include "includes.h"
#include "version.h"
#include "param/pyparam.h"
#include "gpo.h"
#include "ads.h"
#include "secrets.h"
#include "../libds/common/flags.h"
#include "librpc/rpc/pyrpc_util.h"
#include "auth/credentials/pycredentials.h"
#include "libcli/util/pyerrors.h"
#include "python/py3compat.h"
#include "python/modules.h"
#include <pytalloc.h>
#include "../libcli/security/security.h"
/* A Python C API module to use LIBGPO */
#define GPO_getter(ATTR) \
static PyObject* GPO_get_##ATTR(PyObject *self, void *closure) \
{ \
struct GROUP_POLICY_OBJECT *gpo_ptr \
= pytalloc_get_ptr(self); \
\
if (gpo_ptr->ATTR) \
return PyUnicode_FromString(gpo_ptr->ATTR); \
else \
Py_RETURN_NONE; \
}
GPO_getter(ds_path)
GPO_getter(file_sys_path)
GPO_getter(display_name)
GPO_getter(name)
GPO_getter(link)
GPO_getter(user_extensions)
GPO_getter(machine_extensions)
#define GPO_setter(ATTR) \
static int GPO_set_##ATTR(PyObject *self, PyObject *val, void *closure) \
{ \
struct GROUP_POLICY_OBJECT *gpo_ptr \
= pytalloc_get_ptr(self); \
\
if (!PyUnicode_Check(val)) { \
PyErr_Format(PyExc_TypeError, \
"Cannot convert input to string"); \
return -1; \
} \
if (val != Py_None) { \
gpo_ptr->ATTR = talloc_strdup(gpo_ptr, \
_PyUnicode_AsString(val)); \
} else { \
gpo_ptr->ATTR = NULL; \
} \
return 0; \
}
GPO_setter(ds_path)
GPO_setter(file_sys_path)
GPO_setter(display_name)
GPO_setter(name)
GPO_setter(link)
GPO_setter(user_extensions)
GPO_setter(machine_extensions)
#define GPO_int_getter(ATTR) \
static PyObject* GPO_get_##ATTR(PyObject *self, void *closure) \
{ \
struct GROUP_POLICY_OBJECT *gpo_ptr \
= pytalloc_get_ptr(self); \
\
return PyLong_FromLong(gpo_ptr->ATTR); \
}
GPO_int_getter(options)
GPO_int_getter(version)
GPO_int_getter(link_type)
#define GPO_int_setter(ATTR) \
static int GPO_set_##ATTR(PyObject *self, PyObject *val, void *closure) \
{ \
struct GROUP_POLICY_OBJECT *gpo_ptr \
= pytalloc_get_ptr(self); \
\
if (!PyLong_Check(val)) { \
PyErr_Format(PyExc_TypeError, \
"Cannot convert input to int"); \
return -1; \
} else { \
gpo_ptr->ATTR = PyLong_AsLong(val); \
} \
return 0; \
}
GPO_int_setter(options)
GPO_int_setter(version)
GPO_int_setter(link_type)
static PyObject *GPO_marshall_get_sec_desc_buf(PyObject *self, PyObject *args,
PyObject *kwds)
{
struct GROUP_POLICY_OBJECT *gpo_ptr = pytalloc_get_ptr(self);
NTSTATUS status;
uint8_t *data = NULL;
size_t len = 0;
status = marshall_sec_desc(gpo_ptr, gpo_ptr->security_descriptor,
&data, &len);
if (!NT_STATUS_IS_OK(status)) {
PyErr_Format(PyExc_BufferError,
"marshall_sec_desc_buf failed: %s",
nt_errstr(status));
return NULL;
}
return PyBytes_FromStringAndSize((char *)data, len);
}
static PyObject *GPO_unmarshall_set_sec_desc(PyObject *self, PyObject *args,
PyObject *kwds)
{
struct GROUP_POLICY_OBJECT *gpo_ptr = pytalloc_get_ptr(self);
char *bytes = NULL;
size_t length = 0;
NTSTATUS status;
if (!PyArg_ParseTuple(args, "s#", &bytes, &length)) {
PyErr_Format(PyExc_TypeError,
"Cannot convert input to bytes");
return NULL;
}
gpo_ptr->security_descriptor = talloc_zero(gpo_ptr,
struct security_descriptor);
status = unmarshall_sec_desc(gpo_ptr, (uint8_t *)bytes, length,
&gpo_ptr->security_descriptor);
if (!NT_STATUS_IS_OK(status)) {
PyErr_Format(PyExc_BufferError,
"unmarshall_sec_desc failed: %s",
nt_errstr(status));
return NULL;
}
return Py_None;
}
static PyGetSetDef GPO_setters[] = {
{discard_const_p(char, "options"), (getter)GPO_get_options,
(setter)GPO_set_options, NULL, NULL},
{discard_const_p(char, "version"), (getter)GPO_get_version,
(setter)GPO_set_version, NULL, NULL},
{discard_const_p(char, "ds_path"), (getter)GPO_get_ds_path,
(setter)GPO_set_ds_path, NULL, NULL},
{discard_const_p(char, "file_sys_path"), (getter)GPO_get_file_sys_path,
(setter)GPO_set_file_sys_path, NULL, NULL},
{discard_const_p(char, "display_name"), (getter)GPO_get_display_name,
(setter)GPO_set_display_name, NULL, NULL},
{discard_const_p(char, "name"), (getter)GPO_get_name,
(setter)GPO_set_name, NULL, NULL},
{discard_const_p(char, "link"), (getter)GPO_get_link,
(setter)GPO_set_link, NULL, NULL},
{discard_const_p(char, "link_type"), (getter)GPO_get_link_type,
(setter)GPO_set_link_type, NULL, NULL},
{discard_const_p(char, "user_extensions"),
(getter)GPO_get_user_extensions,
(setter)GPO_set_user_extensions, NULL, NULL},
{discard_const_p(char, "machine_extensions"),
(getter)GPO_get_machine_extensions,
(setter)GPO_set_machine_extensions, NULL, NULL},
{0}
};
static PyObject *py_gpo_get_unix_path(PyObject *self, PyObject *args,
PyObject *kwds)
{
NTSTATUS status;
const char *cache_dir = NULL;
PyObject *ret = NULL;
char *unix_path = NULL;
TALLOC_CTX *frame = NULL;
static const char *kwlist[] = {"cache_dir", NULL};
struct GROUP_POLICY_OBJECT *gpo_ptr \
= (struct GROUP_POLICY_OBJECT *)pytalloc_get_ptr(self);
frame = talloc_stackframe();
if (!PyArg_ParseTupleAndKeywords(args, kwds, "|s",
discard_const_p(char *, kwlist),
&cache_dir)) {
goto out;
}
if (!cache_dir) {
cache_dir = cache_path(talloc_tos(), GPO_CACHE_DIR);
if (!cache_dir) {
PyErr_SetString(PyExc_MemoryError,
"Failed to determine gpo cache dir");
goto out;
}
}
status = gpo_get_unix_path(frame, cache_dir, gpo_ptr, &unix_path);
if (!NT_STATUS_IS_OK(status)) {
PyErr_Format(PyExc_RuntimeError,
"Failed to determine gpo unix path: %s",
get_friendly_nt_error_msg(status));
goto out;
}
ret = PyUnicode_FromString(unix_path);
out:
TALLOC_FREE(frame);
return ret;
}
static PyMethodDef GPO_methods[] = {
{"get_unix_path", PY_DISCARD_FUNC_SIG(PyCFunction,
py_gpo_get_unix_path),
METH_VARARGS | METH_KEYWORDS,
NULL },
{"set_sec_desc", PY_DISCARD_FUNC_SIG(PyCFunction,
GPO_unmarshall_set_sec_desc),
METH_VARARGS, NULL },
{"get_sec_desc_buf", PY_DISCARD_FUNC_SIG(PyCFunction,
GPO_marshall_get_sec_desc_buf),
METH_NOARGS, NULL },
{0}
};
static int py_gpo_init(PyObject *self, PyObject *args, PyObject *kwds)
{
struct GROUP_POLICY_OBJECT *gpo_ptr = pytalloc_get_ptr(self);
const char *name = NULL;
const char *display_name = NULL;
enum GPO_LINK_TYPE link_type = GP_LINK_UNKOWN;
const char *file_sys_path = NULL;
static const char *kwlist[] = {
"name", "display_name", "link_type", "file_sys_path", NULL
};
if (!PyArg_ParseTupleAndKeywords(args, kwds, "|ssIs",
discard_const_p(char *, kwlist),
&name, &display_name, &link_type,
&file_sys_path)) {
return -1;
}
if (name) {
gpo_ptr->name = talloc_strdup(gpo_ptr, name);
}
if (display_name) {
gpo_ptr->display_name = talloc_strdup(gpo_ptr, display_name);
}
gpo_ptr->link_type = link_type;
if (file_sys_path) {
gpo_ptr->file_sys_path = talloc_strdup(gpo_ptr, file_sys_path);
}
return 0;
}
static PyObject *py_gpo_new(PyTypeObject *type, PyObject *args, PyObject *kwargs)
{
return pytalloc_new(struct GROUP_POLICY_OBJECT, type);
}
static PyTypeObject GPOType = {
PyVarObject_HEAD_INIT(NULL, 0)
.tp_name = "gpo.GROUP_POLICY_OBJECT",
.tp_doc = "GROUP_POLICY_OBJECT",
.tp_getset = GPO_setters,
.tp_methods = GPO_methods,
.tp_flags = Py_TPFLAGS_DEFAULT | Py_TPFLAGS_BASETYPE,
.tp_new = py_gpo_new,
.tp_init = (initproc)py_gpo_init,
};
typedef struct {
PyObject_HEAD
ADS_STRUCT *ads_ptr;
PyObject *py_creds;
struct cli_credentials *cli_creds;
} ADS;
static void py_ads_dealloc(ADS* self)
{
TALLOC_FREE(self->ads_ptr);
Py_CLEAR(self->py_creds);
Py_TYPE(self)->tp_free((PyObject*)self);
}
static PyObject* py_ads_connect(ADS *self, PyObject *Py_UNUSED(ignored));
static int py_ads_init(ADS *self, PyObject *args, PyObject *kwds)
{
const char *realm = NULL;
const char *workgroup = NULL;
const char *ldap_server = NULL;
PyObject *lp_obj = NULL;
PyObject *py_creds = NULL;
struct loadparm_context *lp_ctx = NULL;
bool ok = false;
static const char *kwlist[] = {
"ldap_server", "loadparm_context", "credentials", NULL
};
if (!PyArg_ParseTupleAndKeywords(args, kwds, "sO|O",
discard_const_p(char *, kwlist),
&ldap_server, &lp_obj, &py_creds)) {
return -1;
}
/* keep reference to the credentials. Clear any earlier ones */
Py_CLEAR(self->py_creds);
self->cli_creds = NULL;
self->py_creds = py_creds;
Py_XINCREF(self->py_creds);
if (self->py_creds) {
ok = py_check_dcerpc_type(self->py_creds, "samba.credentials",
"Credentials");
if (!ok) {
return -1;
}
self->cli_creds
= PyCredentials_AsCliCredentials(self->py_creds);
}
ok = py_check_dcerpc_type(lp_obj, "samba.param", "LoadParm");
if (!ok) {
return -1;
}
lp_ctx = pytalloc_get_type(lp_obj, struct loadparm_context);
if (lp_ctx == NULL) {
return -1;
}
ok = lp_load_initial_only(lp_ctx->szConfigFile);
if (!ok) {
PyErr_Format(PyExc_RuntimeError, "Could not load config file '%s'",
lp_ctx->szConfigFile);
return -1;
}
if (self->cli_creds) {
realm = cli_credentials_get_realm(self->cli_creds);
workgroup = cli_credentials_get_domain(self->cli_creds);
} else {
realm = lp_realm();
workgroup = lp_workgroup();
}
/* in case __init__ is called more than once */
if (self->ads_ptr) {
TALLOC_FREE(self->ads_ptr);
}
/* always succeeds or crashes */
self->ads_ptr = ads_init(pytalloc_get_mem_ctx(args),
realm,
workgroup,
ldap_server,
ADS_SASL_PLAIN);
return 0;
}
/* connect. Failure to connect results in an Exception */
static PyObject* py_ads_connect(ADS *self,
PyObject *Py_UNUSED(ignored))
{
ADS_STATUS status;
TALLOC_CTX *frame = talloc_stackframe();
if (!self->ads_ptr) {
PyErr_SetString(PyExc_RuntimeError, "Uninitialized");
return NULL;
}
ADS_TALLOC_CONST_FREE(self->ads_ptr->auth.user_name);
ADS_TALLOC_CONST_FREE(self->ads_ptr->auth.password);
ADS_TALLOC_CONST_FREE(self->ads_ptr->auth.realm);
if (self->cli_creds) {
self->ads_ptr->auth.user_name = talloc_strdup(self->ads_ptr,
cli_credentials_get_username(self->cli_creds));
if (self->ads_ptr->auth.user_name == NULL) {
PyErr_NoMemory();
goto err;
}
self->ads_ptr->auth.password = talloc_strdup(self->ads_ptr,
cli_credentials_get_password(self->cli_creds));
if (self->ads_ptr->auth.password == NULL) {
PyErr_NoMemory();
goto err;
}
self->ads_ptr->auth.realm = talloc_strdup(self->ads_ptr,
cli_credentials_get_realm(self->cli_creds));
if (self->ads_ptr->auth.realm == NULL) {
PyErr_NoMemory();
goto err;
}
self->ads_ptr->auth.flags |= ADS_AUTH_USER_CREDS;
status = ads_connect_user_creds(self->ads_ptr);
} else {
char *passwd = NULL;
if (!secrets_init()) {
PyErr_SetString(PyExc_RuntimeError,
"secrets_init() failed");
goto err;
}
self->ads_ptr->auth.user_name = talloc_asprintf(self->ads_ptr,
"%s$",
lp_netbios_name());
if (self->ads_ptr->auth.user_name == NULL) {
PyErr_NoMemory();
goto err;
}
passwd = secrets_fetch_machine_password(
self->ads_ptr->server.workgroup, NULL, NULL);
if (passwd == NULL) {
PyErr_SetString(PyExc_RuntimeError,
"Failed to fetch the machine account "
"password");
goto err;
}
self->ads_ptr->auth.password = talloc_strdup(self->ads_ptr,
passwd);
SAFE_FREE(passwd);
if (self->ads_ptr->auth.password == NULL) {
PyErr_NoMemory();
goto err;
}
self->ads_ptr->auth.realm = talloc_asprintf_strupper_m(
self->ads_ptr, "%s", self->ads_ptr->server.realm);
if (self->ads_ptr->auth.realm == NULL) {
PyErr_NoMemory();
goto err;
}
self->ads_ptr->auth.flags |= ADS_AUTH_USER_CREDS;
status = ads_connect(self->ads_ptr);
}
if (!ADS_ERR_OK(status)) {
PyErr_Format(PyExc_RuntimeError,
"ads_connect() failed: %s",
ads_errstr(status));
goto err;
}
TALLOC_FREE(frame);
Py_RETURN_TRUE;
err:
TALLOC_FREE(frame);
return NULL;
}
/* Parameter mapping and functions for the GP_EXT struct */
void initgpo(void);
/* Global methods aka do not need a special pyobject type */
static PyObject *py_gpo_get_sysvol_gpt_version(PyObject * self,
PyObject * args)
{
TALLOC_CTX *tmp_ctx = NULL;
char *unix_path;
char *display_name = NULL;
uint32_t sysvol_version = 0;
PyObject *result;
NTSTATUS status;
if (!PyArg_ParseTuple(args, "s", &unix_path)) {
return NULL;
}
tmp_ctx = talloc_new(NULL);
if (!tmp_ctx) {
return PyErr_NoMemory();
}
status = gpo_get_sysvol_gpt_version(tmp_ctx, unix_path,
&sysvol_version,
&display_name);
if (!NT_STATUS_IS_OK(status)) {
PyErr_SetNTSTATUS(status);
TALLOC_FREE(tmp_ctx);
return NULL;
}
result = Py_BuildValue("[s,i]", display_name, sysvol_version);
talloc_free(tmp_ctx);
return result;
}
#ifdef HAVE_ADS
static ADS_STATUS find_samaccount(ADS_STRUCT *ads, TALLOC_CTX *mem_ctx,
const char *samaccountname,
uint32_t *uac_ret, const char **dn_ret)
{
ADS_STATUS status;
const char *attrs[] = { "userAccountControl", NULL };
const char *filter;
LDAPMessage *res = NULL;
char *dn = NULL;
uint32_t uac = 0;
filter = talloc_asprintf(mem_ctx, "(sAMAccountName=%s)",
samaccountname);
if (filter == NULL) {
status = ADS_ERROR_NT(NT_STATUS_NO_MEMORY);
goto out;
}
status = ads_do_search_all(ads, ads->config.bind_path,
LDAP_SCOPE_SUBTREE, filter, attrs, &res);
if (!ADS_ERR_OK(status)) {
goto out;
}
if (ads_count_replies(ads, res) != 1) {
status = ADS_ERROR(LDAP_NO_RESULTS_RETURNED);
goto out;
}
dn = ads_get_dn(ads, talloc_tos(), res);
if (dn == NULL) {
status = ADS_ERROR(LDAP_NO_MEMORY);
goto out;
}
if (!ads_pull_uint32(ads, res, "userAccountControl", &uac)) {
status = ADS_ERROR(LDAP_NO_SUCH_ATTRIBUTE);
goto out;
}
if (uac_ret) {
*uac_ret = uac;
}
if (dn_ret) {
*dn_ret = talloc_strdup(mem_ctx, dn);
if (*dn_ret == NULL) {
status = ADS_ERROR(LDAP_NO_MEMORY);
goto out;
}
}
out:
TALLOC_FREE(dn);
ads_msgfree(ads, res);
return status;
}
static PyObject *py_ads_get_gpo_list(ADS *self, PyObject *args, PyObject *kwds)
{
TALLOC_CTX *frame = NULL;
struct GROUP_POLICY_OBJECT *gpo = NULL, *gpo_list = NULL;
ADS_STATUS status;
const char *samaccountname = NULL;
const char *dn = NULL;
uint32_t uac = 0;
uint32_t flags = 0;
struct security_token *token = NULL;
PyObject *ret = NULL;
TALLOC_CTX *gpo_ctx = NULL;
size_t list_size;
size_t i;
static const char *kwlist[] = {"samaccountname", NULL};
PyErr_WarnEx(PyExc_DeprecationWarning, "The get_gpo_list function"
" is deprecated as of Samba 4.19. Please use "
"the samba.gp module instead.", 2);
if (!PyArg_ParseTupleAndKeywords(args, kwds, "s",
discard_const_p(char *, kwlist),
&samaccountname)) {
return NULL;
}
if (!self->ads_ptr) {
PyErr_SetString(PyExc_RuntimeError, "Uninitialized");
return NULL;
}
frame = talloc_stackframe();
status = find_samaccount(self->ads_ptr, frame,
samaccountname, &uac, &dn);
if (!ADS_ERR_OK(status)) {
PyErr_Format(PyExc_RuntimeError,
"Failed to find samAccountName '%s': %s",
samaccountname, ads_errstr(status));
goto out;
}
if (uac & UF_WORKSTATION_TRUST_ACCOUNT ||
uac & UF_SERVER_TRUST_ACCOUNT) {
flags |= GPO_LIST_FLAG_MACHINE;
status = gp_get_machine_token(self->ads_ptr, frame, dn,
&token);
if (!ADS_ERR_OK(status)) {
PyErr_Format(PyExc_RuntimeError,
"Failed to get machine token for '%s'(%s): %s",
samaccountname, dn, ads_errstr(status));
goto out;
}
} else {
status = ads_get_sid_token(self->ads_ptr, frame, dn, &token);
if (!ADS_ERR_OK(status)) {
PyErr_Format(PyExc_RuntimeError,
"Failed to get sid token for '%s'(%s): %s",
samaccountname, dn, ads_errstr(status));
goto out;
}
}
gpo_ctx = talloc_new(frame);
if (!gpo_ctx) {
PyErr_NoMemory();
goto out;
}
status = ads_get_gpo_list(self->ads_ptr, gpo_ctx, dn, flags, token,
&gpo_list);
if (!ADS_ERR_OK(status)) {
PyErr_Format(PyExc_RuntimeError,
"Failed to fetch GPO list: %s",
ads_errstr(status));
goto out;
}
/* Convert the C linked list into a python list */
list_size = 0;
for (gpo = gpo_list; gpo != NULL; gpo = gpo->next) {
list_size++;
}
i = 0;
ret = PyList_New(list_size);
if (ret == NULL) {
goto out;
}
for (gpo = gpo_list; gpo != NULL; gpo = gpo->next) {
PyObject *obj = pytalloc_reference_ex(&GPOType,
gpo_ctx, gpo);
if (obj == NULL) {
Py_CLEAR(ret);
goto out;
}
PyList_SetItem(ret, i, obj);
i++;
}
out:
TALLOC_FREE(frame);
return ret;
}
#endif
static PyMethodDef ADS_methods[] = {
{ "connect", (PyCFunction)py_ads_connect, METH_NOARGS,
"Connect to the LDAP server" },
#ifdef HAVE_ADS
{ "get_gpo_list", PY_DISCARD_FUNC_SIG(PyCFunction, py_ads_get_gpo_list),
METH_VARARGS | METH_KEYWORDS,
NULL },
#endif
{0}
};
static PyTypeObject ads_ADSType = {
.tp_name = "gpo.ADS_STRUCT",
.tp_basicsize = sizeof(ADS),
.tp_new = PyType_GenericNew,
.tp_dealloc = (destructor)py_ads_dealloc,
.tp_flags = Py_TPFLAGS_DEFAULT,
.tp_doc = "ADS struct",
.tp_methods = ADS_methods,
.tp_init = (initproc)py_ads_init,
};
static PyMethodDef py_gpo_methods[] = {
{"gpo_get_sysvol_gpt_version",
(PyCFunction)py_gpo_get_sysvol_gpt_version,
METH_VARARGS, NULL},
{0}
};
static struct PyModuleDef moduledef = {
PyModuleDef_HEAD_INIT,
.m_name = "gpo",
.m_doc = "libgpo python bindings",
.m_size = -1,
.m_methods = py_gpo_methods,
};
/* Will be called by python when loading this module */
void initgpo(void);
MODULE_INIT_FUNC(gpo)
{
PyObject *m;
debug_setup_talloc_log();
/* Instantiate the types */
m = PyModule_Create(&moduledef);
if (m == NULL) {
goto err;
}
if (PyModule_AddObject(m, "version",
PyUnicode_FromString(SAMBA_VERSION_STRING)) ) {
goto err;
}
if (pytalloc_BaseObject_PyType_Ready(&ads_ADSType) < 0) {
goto err;
}
Py_INCREF(&ads_ADSType);
if (PyModule_AddObject(m, "ADS_STRUCT", (PyObject *)&ads_ADSType)) {
goto err;
}
if (pytalloc_BaseObject_PyType_Ready(&GPOType) < 0) {
goto err;
}
Py_INCREF((PyObject *)(void *)&GPOType);
if (PyModule_AddObject(m, "GROUP_POLICY_OBJECT",
(PyObject *)&GPOType)) {
goto err;
}
#define ADD_FLAGS(val) PyModule_AddObject(m, #val, PyLong_FromLong(val))
ADD_FLAGS(GP_LINK_UNKOWN);
ADD_FLAGS(GP_LINK_MACHINE);
ADD_FLAGS(GP_LINK_SITE);
ADD_FLAGS(GP_LINK_DOMAIN);
ADD_FLAGS(GP_LINK_OU);
ADD_FLAGS(GP_LINK_LOCAL);
return m;
err:
Py_CLEAR(m);
return NULL;
}