postgresql影子用户实践场景分析

原作者: [db:作者] 来自: [db:来源] 收藏邀请

在实际的生产环境，我们经常会碰到这样的情况：因为业务场景需要，本部门某些重要的业务数据表需要给予其他部门查看权限，因业务的扩展及调整，后期可能需要放开更多的表查询权限。为解决此种业务需求，我们可以采用创建视图的方式来解决，已可以通过创建影子用户的方式来满足需求，本文主要介绍影子用户的创建及授权方法。

场景1：只授予usage on schema 权限

session 1:
--创建readonly用户，并将test模式赋予readonly用户。

postgres=# create user readonly with password 'postgres';
CREATE ROLE
postgres=# grant usage on schema test to readonly;
GRANT
postgres=# \dn
List of schemas
 Name | Owner 
-------+-------
 test | postgres

session 2:

--登陆readonly用户可以查询test模式下现存的所有表。

postgres=# \c postgres readonly 
You are now connected to database "postgres" as user "readonly".
postgres=> select * from test.emp ;
 empno | ename |  job  | mgr | hiredate |  sal  | comm  | deptno 
-------+--------+-----------+------+------------+---------+---------+--------
 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 | 1600.00 | 300.00 |   30
 7521 | WARD  | SALESMAN | 7698 | 1981-02-22 | 1250.00 | 500.00 |   30
 7566 | JONES | MANAGER  | 7839 | 1981-04-02 | 2975.00 |     |   20
 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 | 1250.00 | 1400.00 |   30
 7698 | BLAKE | MANAGER  | 7839 | 1981-05-01 | 2850.00 |     |   30
 7782 | CLARK | MANAGER  | 7839 | 1981-06-09 | 2450.00 |     |   10
 7839 | KING  | PRESIDENT |   | 1981-11-17 | 5000.00 |     |   10
 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 | 1500.00 |  0.00 |   30
 7900 | JAMES | CLERK   | 7698 | 1981-12-03 | 950.00 |     |   30
 7902 | FORD  | ANALYST  | 7566 | 1981-12-03 | 3000.00 |     |   20
 7934 | MILLER | CLERK   | 7782 | 1982-01-23 | 1300.00 |     |   10
 7788 | test  | ANALYST  | 7566 | 1982-12-09 | 3000.00 |     |   20
 7876 | ADAMS | CLERK   | 7788 | 1983-01-12 | 1100.00 |     |   20
 1111 | SMITH | CLERK   | 7902 | 1980-12-17 | 800.00 |     |   20
(14 rows)

换到session 1创建新表t1

postgres=# create table test.t1 as select * from test.emp;
CREATE TABLE

切换到session 2 readonly用户下，t1表无法查询

postgres=> select * from test.t1 ;
2021-03-02 15:25:33.290 CST [21059] ERROR: permission denied for table t1
2021-03-02 15:25:33.290 CST [21059] STATEMENT: select * from test.t1 ;
**ERROR: permission denied for table t1

结论：如果只授予 usage on schema 权限，readonly 只能查看 test 模式下已经存在的表和对象。在授予 usage on schema 权限之后创建的新表无法查看。

场景2：授予usage on schema 权限之后，再赋予 select on all tables in schema 权限

针对上个场景session 2 **ERROR: permission denied for table t1 错误的处理

postgres=> select * from test.t1 ;
**ERROR: permission denied for table t1

session 1：使用postgres用户授予readonly用户 select on all tables 权限

postgres=# grant select on all tables in schema test TO readonly ;

session 2: readonly用户查询 t1 表

postgres=> select * from test.t1;
 empno | ename |  job  | mgr | hiredate |  sal  | comm  | deptno 
-------+--------+-----------+------+------------+---------+---------+--------
 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 | 1600.00 | 300.00 |   30
 7521 | WARD  | SALESMAN | 7698 | 1981-02-22 | 1250.00 | 500.00 |   30
 7566 | JONES | MANAGER  | 7839 | 1981-04-02 | 2975.00 |     |   20
 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 | 1250.00 | 1400.00 |   30
 7698 | BLAKE | MANAGER  | 7839 | 1981-05-01 | 2850.00 |     |   30
 7782 | CLARK | MANAGER  | 7839 | 1981-06-09 | 2450.00 |     |   10
 7839 | KING  | PRESIDENT |   | 1981-11-17 | 5000.00 |     |   10
 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 | 1500.00 |  0.00 |   30
 7900 | JAMES | CLERK   | 7698 | 1981-12-03 | 950.00 |     |   30
 7902 | FORD  | ANALYST  | 7566 | 1981-12-03 | 3000.00 |     |   20
 7934 | MILLER | CLERK   | 7782 | 1982-01-23 | 1300.00 |     |   10
 7788 | test  | ANALYST  | 7566 | 1982-12-09 | 3000.00 |     |   20
 7876 | ADAMS | CLERK   | 7788 | 1983-01-12 | 1100.00 |     |   20
 1111 | SMITH | CLERK   | 7902 | 1980-12-17 | 800.00 |     |   20
(14 rows)

session1 ：postgres用户的test模式下创建新表 t2

postgres=# create table test.t2 as select * from test.emp;
SELECT 14

session 2：readonly用户查询 t2 表权限不足

postgres=> select * from test.t2 ;
ERROR: permission denied for table t2

session 1：再次赋予 grant select on all tables

postgres=# grant select on all tables in schema test TO readonly ;

session 2：readonly用户又可以查看 T2 表

postgres=> select * from test.t2 ;
 empno | ename |  job  | mgr | hiredate |  sal  | comm  | deptno 
-------+--------+-----------+------+------------+---------+---------+--------
 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 | 1600.00 | 300.00 |   30
 7521 | WARD  | SALESMAN | 7698 | 1981-02-22 | 1250.00 | 500.00 |   30
 7566 | JONES | MANAGER  | 7839 | 1981-04-02 | 2975.00 |     |   20
 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 | 1250.00 | 1400.00 |   30
 7698 | BLAKE | MANAGER  | 7839 | 1981-05-01 | 2850.00 |     |   30
 7782 | CLARK | MANAGER  | 7839 | 1981-06-09 | 2450.00 |     |   10
 7839 | KING  | PRESIDENT |   | 1981-11-17 | 5000.00 |     |   10
 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 | 1500.00 |  0.00 |   30
 7900 | JAMES | CLERK   | 7698 | 1981-12-03 | 950.00 |     |   30
 7902 | FORD  | ANALYST  | 7566 | 1981-12-03 | 3000.00 |     |   20
 7934 | MILLER | CLERK   | 7782 | 1982-01-23 | 1300.00 |     |   10
 7788 | test  | ANALYST  | 7566 | 1982-12-09 | 3000.00 |     |   20
 7876 | ADAMS | CLERK   | 7788 | 1983-01-12 | 1100.00 |     |   20
 1111 | SMITH | CLERK   | 7902 | 1980-12-17 | 800.00 |     |   20
(14 rows)

影子用户创建

如果想让readonly只读用户不在每次 postgres用户在test模式中创建新表后都要手工赋予 grant select on all tables in schema test TO readonly 权限。则需要授予对test默认的访问权限，对于test模式新创建的也生效。

session 1：未来访问test模式下所有新建的表赋权，创建 t5 表。

postgres=# alter default privileges in schema test grant select on tables to readonly ;
ALTER DEFAULT PRIVILEGES
postgres=# create table test.t5 as select * from test.emp;
CREATE TABLE

session 2：查询readonly用户

postgres=> select * from test.t5;
 empno | ename |  job  | mgr | hiredate |  sal  | comm  | deptno 
-------+--------+-----------+------+------------+---------+---------+--------
 7499 | ALLEN | SALESMAN | 7698 | 1981-02-20 | 1600.00 | 300.00 |   30
 7521 | WARD  | SALESMAN | 7698 | 1981-02-22 | 1250.00 | 500.00 |   30
 7566 | JONES | MANAGER  | 7839 | 1981-04-02 | 2975.00 |     |   20
 7654 | MARTIN | SALESMAN | 7698 | 1981-09-28 | 1250.00 | 1400.00 |   30
 7698 | BLAKE | MANAGER  | 7839 | 1981-05-01 | 2850.00 |     |   30
 7782 | CLARK | MANAGER  | 7839 | 1981-06-09 | 2450.00 |     |   10
 7839 | KING  | PRESIDENT |   | 1981-11-17 | 5000.00 |     |   10
 7844 | TURNER | SALESMAN | 7698 | 1981-09-08 | 1500.00 |  0.00 |   30
 7900 | JAMES | CLERK   | 7698 | 1981-12-03 | 950.00 |     |   30
 7902 | FORD  | ANALYST  | 7566 | 1981-12-03 | 3000.00 |     |   20
 7934 | MILLER | CLERK   | 7782 | 1982-01-23 | 1300.00 |     |   10
 7788 | test  | ANALYST  | 7566 | 1982-12-09 | 3000.00 |     |   20
 7876 | ADAMS | CLERK   | 7788 | 1983-01-12 | 1100.00 |     |   20
 1111 | SMITH | CLERK   | 7902 | 1980-12-17 | 800.00 |     |   20
(14 rows)

总结：影子用户创建的步骤

--创建影子用户
create user readonly with password 'postgres';
--将schema中usage权限赋予给readonly用户,访问所有已存在的表
grant usage on schema test to readonly;
grant select on all tables in schema test to readonly;
--未来访问test模式下所有新建的表
alter default privileges in schema test grant select on tables to readonly ;

到此这篇关于postgresql影子用户实践的文章就介绍到这了,更多相关postgresql影子用户内容请搜索极客世界以前的文章或继续浏览下面的相关文章希望大家以后多多支持极客世界！