Oracle 赋权和回收权限的生效时间

Oracle赋权的回收权限是使用grant和revoke语句，但是赋权和回收权限语句执行完成后就会立即生效么？另外Oracle的权限又分为系统权限、角色权限和对象权限，这三种权限的grant和revoke生效时间又是怎样的呢。我们来看官方文档是如何说的：

Depending on what is granted or revoked, a grant or revoke takes effect at different times:

• All grants and revokes of system and object privileges to anything (users, roles, and PUBLIC) take immediate effect.

• All grants and revokes of roles to anything (users, other roles, PUBLIC) take effect only when a current user session issues a SET ROLE statement to reenable the role after the grant and revoke, or when a new user session is created after the grant or revoke.

You can see which roles are currently enabled by examining the SESSION_ROLES data dictionary view.

从上面的描述中我们可以知道，grant和revoke系统权限和对象权限时会立即生效，而grant或revoke角色时对当前会话不会立即生效，除非使用set role语句启用角色或重新连接会话后设置才会生效。

下面以11.2.0.4为例做一个测试，是否与官方文档描述的一致。

一、首先创建一个测试用户，赋予connect角色

sys@ORCL>create user zhaoxu identified by zhaoxu;User created.sys@ORCL>grant connect to zhaoxu;Grant succeeded.sys@ORCL>select * from dba_role_privs where grantee='ZHAOXU';GRANTEE                   GRANTED_ROLE                ADMIN_OPT DEFAULT_R------------------------------ ------------------------------ --------- ---------ZHAOXU                         CONNECT                             NO  YESsys@ORCL>select * from dba_sys_privs where grantee='ZHAOXU';no rows selectedsys@ORCL>select * from dba_tab_privs where grantee='ZHAOXU';no rows selectedsys@ORCL>conn zhaoxu/zhaoxuConnected.zhaoxu@ORCL>select * from session_roles;ROLE------------------------------------------------------------CONNECTzhaoxu@ORCL>select * from session_privs;PRIVILEGE------------------------------------------------------------CREATE SESSIONzhaoxu@ORCL>create table t (id number) segment creation immediate;create table t (id number)*ERROR at line 1:ORA-01031: insufficient privileges

现在的zhaoxu用户只有CONNECT角色，只能连接到数据库，其他基本什么都做不了。

二、测试系统权限和对象权限的grant和revoke

现在打开另一个会话赋予system privilege给zhaoxu用户

--session 2sys@ORCL>grant create table,unlimited tablespace to zhaoxu;Grant succeeded.--session 1zhaoxu@ORCL>select * from session_privs;PRIVILEGE------------------------------------------------------------------------------------------------------------------------CREATE SESSIONUNLIMITED TABLESPACECREATE TABLEzhaoxu@ORCL>select * from session_roles;ROLE------------------------------------------------------------------------------------------CONNECTzhaoxu@ORCL>create table t (id number) segment creation immediate;Table created.--使用segment creation immediate是因为要避免11g的新特性段延迟创建造成影响

在赋予zhaoxu用户create table和unlimited tablespace系统权限全会话1没有做任何操作，权限就会立即生效。

再测试revoke权限的情况

--session 2sys@ORCL>revoke unlimited tablespace from zhaoxu;Revoke succeeded.--session 1zhaoxu@ORCL>create table t1 (id number) segment creation immediate;create table t1 (id number) segment creation immediate*ERROR at line 1:ORA-01950: no privileges on tablespace 'USERS'zhaoxu@ORCL>select * from session_privs;PRIVILEGE------------------------------------------------------------------------------------------------------------------------CREATE SESSIONCREATE TABLE

同样可以看到回收操作可以立即生效，现有session无需做任何操作。

测试对象权限的grant和revoke

--grant测试--session 1zhaoxu@ORCL>select count(*) from zx.t;select count(*) from zx.t                        *ERROR at line 1:ORA-00942: table or view does not exist--session 2sys@ORCL>grant select on zx.t to zhaoxu;Grant succeeded.sys@ORCL>select * from dba_tab_privs where grantee='ZHAOXU';GRANTEE                   OWNER                       TABLE_NAME GRANTOR    PRIVILEGE  GRANTABLE HIERARCHY------------------------------ ------------------------------ ---------- ---------- ---------- --------- ---------ZHAOXU                         ZX                          T       ZX            SELECT     NO   NO--session 1zhaoxu@ORCL>select count(*) from zx.t;  COUNT(*)----------     99999zhaoxu@ORCL>select * from session_privs;PRIVILEGE------------------------------------------------------------------------------------------------------------------------CREATE SESSIONCREATE TABLE--revoke测试--session 2sys@ORCL>revoke select on zx.t from zhaoxu;Revoke succeeded.sys@ORCL>select * from dba_tab_privs where grantee='ZHAOXU';no rows selected--session 1zhaoxu@ORCL>select count(*) from zx.t;select count(*) from zx.t                        *ERROR at line 1:ORA-00942: table or view does not exist

对对象权限的grant和revoke操作与系统权限的一致，所有的命令都是立即生效，包括对已经连接的会话。

三、测试角色的grant和revoke

现在的zhaoxu用户仍然只有connect角色，并且已经打开一个会话

--session 2sys@ORCL>select * from dba_role_privs where grantee='ZHAOXU';GRANTEE                   GRANTED_ROLE                ADMIN_OPT DEFAULT_R------------------------------ ------------------------------ --------- ---------ZHAOXU                         CONNECT                             NO  YES--session 1zhaoxu@ORCL>select * from session_roles;ROLE------------------------------------------CONNECT

测试grant DBA权限

--session 1查看会话中的角色zhaoxu@ORCL>select * from session_roles;ROLE------------------------------------------------------------------------------------------CONNECT--session 2赋予zhaoxu用户dba角色sys@ORCL>grant dba to zhaoxu;Grant succeeded.sys@ORCL>select * from dba_role_privs where grantee='ZHAOXU';GRANTEE                   GRANTED_ROLE                ADMIN_OPT DEFAULT_R------------------------------ ------------------------------ --------- ---------ZHAOXU                         DBA                         NO  YESZHAOXU                         CONNECT                             NO  YES--session 1再次查看会话中的角色，没有dba角色，也没有查看v$session的权限zhaoxu@ORCL>select * from session_roles;ROLE------------------------------------------------------------------------------------------CONNECTzhaoxu@ORCL>select count(*) from v$session;select count(*) from v$session                     *ERROR at line 1:ORA-00942: table or view does not exist--session 1执行set role命令，可以看到DBA及相关的角色已经加载到session1中了，也可以查询v$sessionzhaoxu@ORCL>set role dba;Role set.zhaoxu@ORCL>select * from session_roles;ROLE------------------------------------------------------------------------------------------DBASELECT_CATALOG_ROLEHS_ADMIN_SELECT_ROLE......19 rows selected.zhaoxu@ORCL>select count(*) from v$session;  COUNT(*)----------        29--使用zhaoxu用户打开session 3，可以看到新会话中默认会加载DBA及相关角色[oracle@rhel6 ~]$ sqlplus zhaoxu/zhaoxuSQL*Plus: Release 11.2.0.4.0 Production on Sat Jan 21 16:22:01 2017Copyright (c) 1982, 2013, Oracle.  All rights reserved.Connected to:Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing optionszhaoxu@ORCL>select * from session_roles;ROLE------------------------------------------------------------------------------------------CONNECTDBASELECT_CATALOG_ROLE......20 rows selected.

测试revoke DBA角色

--session 2回收DBA角色sys@ORCL>revoke dba from zhaoxu;Revoke succeeded.sys@ORCL>select * from dba_role_privs where grantee='ZHAOXU';GRANTEE                   GRANTED_ROLE                ADMIN_OPT DEFAULT_R------------------------------ ------------------------------ --------- ---------ZHAOXU                         CONNECT                             NO  YES--session 3查看会话的角色，仍然有DBA及相关角色zhaoxu@ORCL>select * from session_roles;ROLE------------------------------------------------------------------------------------------CONNECTDBASELECT_CATALOG_ROLE......20 rows selected.--使用zhaoxu用户打开session 4，查看只有CONNECT角色[oracle@rhel6 ~]$ sqlplus zhaoxu/zhaoxuSQL*Plus: Release 11.2.0.4.0 Production on Sat Jan 21 16:30:19 2017Copyright (c) 1982, 2013, Oracle.  All rights reserved.Connected to:Oracle Database 11g Enterprise Edition Release 11.2.0.4.0 - 64bit ProductionWith the Partitioning, OLAP, Data Mining and Real Application Testing optionszhaoxu@ORCL>select * from session_roles;ROLE------------------------------------------------------------------------------------------CONNECT--session 3执行set role命令zhaoxu@ORCL>set role dba;set role dba*ERROR at line 1:ORA-01924: role 'DBA' not granted or does not existzhaoxu@ORCL>set role all;Role set.zhaoxu@ORCL>select * from session_roles;ROLE------------------------------------------------------------------------------------------CONNECT

从上面的测试中可以总结出，grant和revoke系统权限和对象权限时会立即生效，而grant或revoke角色时对当前会话不会立即生效，除非使用set role语句启用角色或重新连接会话后设置才会生效。与官方文档的描述一致。

但是有一个问题是如果查看已经连接的其他会话所拥有的role呢？

官方文档：http://docs.oracle.com/cd/E11882_01/network.112/e36292/authorization.htm#DBSEG99974

system privilege:http://docs.oracle.com/cd/E11882_01/server.112/e41084/statements_9013.htm#BABEFFEE

object privilege:http://docs.oracle.com/cd/E11882_01/server.112/e41084/statements_9013.htm#BGBCIIEG

set role:http://docs.oracle.com/cd/E11882_01/server.112/e41084/statements_10004.htm#SQLRF01704