• 如何使用Python连接ldap


    如何使用Python连接ldap

    好多使用ldap认证的软件都是Python的,比如superset和airflow, 好吧,他们都是airbnb家的。在配置ldap的时候可能会出现认证失败,你不知道是因为什么导致配置失败的。所以,就要
    跟踪源码,看看内部怎么认证实现的。

    ldap介绍和使用安装参见: https://www.cnblogs.com/woshimrf/p/ldap.html

    登录的源码参见: https://github.com/apache/airflow/blob/70e937a8d8ff308a9fb9055ceb7ef2c034200b36/airflow/contrib/auth/backends/ldap_auth.py#L191

    具体来实现如下:

    为了模拟环境,我们使用docker-python。基于Debian Python3: https://github.com/Ryan-Miao/docker-china-source/tree/master/docker-python

    启动

    docker run -it ryan/python:3 /bin/bash
    

    下载ldap3

    pip install ldap3
    

    测试连接

    root@5edee218d962:/# python
    Python 3.7.4 (default, Jul 13 2019, 14:20:24) 
    [GCC 6.3.0 20170516] on linux
    Type "help", "copyright", "credits" or "license" for more information.
    >>> from ldap3 import Server, Connection, ALL, NTLM, ALL_ATTRIBUTES, LEVEL, SUBTREE
    >>> server = Server('172.17.0.2', get_info=ALL)
    >>> conn = Connection(server, 'cn=admin,dc=demo,dc=com', 'admin', auto_bind=True)
    >>> conn.extend.standard.who_am_i()
    'dn:cn=admin,dc=demo,dc=com'
    

    测试登录部分

    登录源码如下:

    @staticmethod
        def try_login(username, password):
            conn = get_ldap_connection(configuration.conf.get("ldap", "bind_user"),
                                       configuration.conf.get("ldap", "bind_password"))
    
            search_filter = "(&({0})({1}={2}))".format(
                configuration.conf.get("ldap", "user_filter"),
                configuration.conf.get("ldap", "user_name_attr"),
                username
            )
    
            search_scope = LEVEL
            if configuration.conf.has_option("ldap", "search_scope"):
                if configuration.conf.get("ldap", "search_scope") == "SUBTREE":
                    search_scope = SUBTREE
                else:
                    search_scope = LEVEL
    
            # todo: BASE or ONELEVEL?
    
            res = conn.search(configuration.conf.get("ldap", "basedn"), search_filter, search_scope=search_scope)
    
            # todo: use list or result?
            if not res:
                log.info("Cannot find user %s", username)
                raise AuthenticationError("Invalid username or password")
    
            entry = conn.response[0]
    
            conn.unbind()
    
            if 'dn' not in entry:
                # The search filter for the user did not return any values, so an
                # invalid user was used for credentials.
                raise AuthenticationError("Invalid username or password")
    
            try:
                conn = get_ldap_connection(entry['dn'], password)
            except KeyError:
                log.error("""
                Unable to parse LDAP structure. If you're using Active Directory
                and not specifying an OU, you must set search_scope=SUBTREE in airflow.cfg.
                %s
                """, traceback.format_exc())
                raise LdapException(
                    "Could not parse LDAP structure. "
                    "Try setting search_scope in airflow.cfg, or check logs"
                )
    
            if not conn:
                log.info("Password incorrect for user %s", username)
                raise AuthenticationError("Invalid username or password")
    
    

    第一步: 获取连接

    from ldap3 import Server, Connection, ALL, NTLM, ALL_ATTRIBUTES, LEVEL, SUBTREE
    
    
    server = Server('172.17.0.2:389', get_info=ALL)
    conn = Connection(server, 'cn=admin,dc=demo,dc=com', 'admin', auto_bind=True)
    conn.extend.standard.who_am_i()
    

    第二步: 根据filter search用户。 这里我们的配置文件如下:

    [ldap]
    # set this to ldaps://<your.ldap.server>:<port>
    uri = ldap://172.17.0.2:389
    user_filter = objectClass=inetOrgPerson
    user_name_attr = sn
    group_member_attr = memberOf
    superuser_filter =
    data_profiler_filter =
    bind_user = cn=admin,dc=demo,dc=com
    bind_password = admin
    basedn = dc=demo,dc=com
    cacert =
    search_scope = SUBTREE
    

    源码就是拼接filter, 最后变成(&(objectClass=inetOrgPerson)(sn=ryanmiao)), 然后search scope.

    
    >>> with Connection(server, 'cn=admin,dc=demo,dc=com', 'admin') as conn:
    ...         conn.search('dc=demo,dc=com', '(&(objectClass=inetOrgPerson)(cn=hr-ryan))', search_scope=SUBTREE)
    ...         entry = conn.entries[0]
    ... 
    True
    >>> entry
    DN: cn=hr-ryan,ou=HR,ou=People,dc=demo,dc=com - STATUS: Read - READ TIME: 2019-08-19T12:58:34.966181
    
    

    第三步: 从上一步得到dn,然后根据用户输入的密码,再次连接, 不抛异常就证明密码正确

    >>> conn = Connection(server, 'cn=hr-ryan,ou=HR,ou=People,dc=demo,dc=com', '123456', auto_bind=True)
    >>> 
    >>> conn = Connection(server, 'cn=hr-ryan,ou=HR,ou=People,dc=demo,dc=com', '1234567', auto_bind=True)
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "/usr/local/lib/python3.7/site-packages/ldap3/core/connection.py", line 325, in __init__
        self.do_auto_bind()
      File "/usr/local/lib/python3.7/site-packages/ldap3/core/connection.py", line 353, in do_auto_bind
        raise LDAPBindError(self.last_error)
    ldap3.core.exceptions.LDAPBindError: automatic bind not successful - invalidCredentials
    
    

    测试分组

    ldap提供了分组,配置见前文。我们采用ldap统一登录之后,还要把用户放入不同的group里来区分权限。比如splunk-users, splunk-admin, gitlab-admin, gitlab-user等。

    根据用户名和密码,我们实现了用户登录密码验证,接下来需要取到用户所属于的group。

    源码如下:

    
    def groups_user(conn, search_base, user_filter, user_name_att, username):
        search_filter = "(&({0})({1}={2}))".format(user_filter, user_name_att, username)
        try:
            memberof_attr = configuration.conf.get("ldap", "group_member_attr")
        except Exception:
            memberof_attr = "memberOf"
        res = conn.search(search_base, search_filter, attributes=[memberof_attr])
        if not res:
            log.info("Cannot find user %s", username)
            raise AuthenticationError("Invalid username or password")
    
        if conn.response and memberof_attr not in conn.response[0]["attributes"]:
            log.warning("""Missing attribute "%s" when looked-up in Ldap database.
            The user does not seem to be a member of a group and therefore won't see any dag
            if the option filter_by_owner=True and owner_mode=ldapgroup are set""",
                        memberof_attr)
            return []
    
        user_groups = conn.response[0]["attributes"][memberof_attr]
    
        regex = re.compile("cn=([^,]*).*", re.IGNORECASE)
        groups_list = []
        try:
            groups_list = [regex.search(i).group(1) for i in user_groups]
        except IndexError:
            log.warning("Parsing error when retrieving the user's group(s)."
                        " Check if the user belongs to at least one group"
                        " or if the user's groups name do not contain special characters")
    
        return groups_list
    

    同样,第一步,连接,第二步search,但需要返回字段memberof。注意我们前面配置了group_member_attr=memberof

    >>> with Connection(server, 'cn=admin,dc=demo,dc=com', 'admin') as conn:
    ...         conn.search('dc=demo,dc=com', '(&(objectClass=inetOrgPerson)(sn=hr-ryan))', attributes=['memberof'])
    ...         entry = conn.entries[0]
    ...         entry
    ... 
    True
    DN: cn=hr-ryan,ou=HR,ou=People,dc=demo,dc=com - STATUS: Read - READ TIME: 2019-08-19T13:05:20.592805
        memberOf: cn=g-admin,ou=Group,dc=demo,dc=com
                  cn=g-users,ou=Group,dc=demo,dc=com
                  cn=g-a,ou=Group,dc=demo,dc=com
    
    

    如果取不到group会报错。

    以上就差不多是airflow的ldap配置原理了。其他雷同,不一样的地方也许是在filter的地方,我们找对应软件的源码look一下就ok了。

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  • 原文地址:https://www.cnblogs.com/woshimrf/p/ldap-python.html
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