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  • postgresql影子用户实践场景分析
  • 2021/3/6 9:08:14
  • 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 ;

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