postgresql影子用户实践场景分析

时间:2022-06-01 22:15:02

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。

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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。

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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

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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

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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

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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

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

session 2: readonly用户查询 t1 表

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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

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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

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

session 1:再次赋予 grant select on all tables

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

session 2:readonly用户又可以查看 T2 表

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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。

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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

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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

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--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 ;

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原文链接:https://blog.csdn.net/pg_hgdb/article/details/114313062