Database-Authorization and recovery security

Computer system security

Establish and implement various security measures for computer system to protect the hardware, software and data in computer system, prevent it from being damaged by accidental or malicious reasons, data being changed or leaked, etc.

 问题的提出数据库的一大特点是数据可以共享数据共享必然带来数据库的安全性问题数据库系统中的数据共享不能是无条件的共享例： 军事秘密、国家机密、新产品实验数据、        市场需求分析、市场营销策略、销售计划、        客户档案、医疗档案、银行储蓄数据

EC/TDI Security Level Division

B2 and above system
is still in the theoretical research stage
Applications are limited to some special departments, such as the army, etc.
The United States is aggressively developing security products, trying to offload B2 security levels currently confined to a few areas of application to commercial applications, and gradually becoming new business standards

Cc

Cc
An internationally recognized structure for the security of Information technology
The security requirements of information products are divided into
Security Feature requirements
Safety Assurance Requirements

Overview of database Security controls

illegal use of databases
Writing a legitimate program to bypass the DBMS and its authorization mechanism
Perform unauthorized operations directly or by writing applications
Some classified data are deduced from the database by several legal queries.

User identification and identification

(Identification & Authentication)
The outermost security measures provided by the system
User ID
Password
System checks passwords to identify user identities
User names and passwords are easily stolen
Each user is pre-contracted to good one the calculation process or function

Access control mechanism

Composition
Define user Rights
Legal permission Check
The security subsystem of DBMS is composed of user privilege definition and legal right check mechanism.
Common access control methods
Autonomous access controls (discretionary access control, referred to as DAC)
C2 class
Flexible
Forced access Control (Mandatory access controls, referred to as MAC)
B1 class
Strict

Autonomous access Control method

Implemented by the GRANT statement and the REVOKE statement of SQL
User Rights composition
Data Objects
Type of operation
Define user access rights: Define what types of operations users can perform on which database objects
Defining access rights is called authorization

Licensing and Recycling

一、GRANTGRANT语句的一般格式：       GRANT <权限>[,<权限>]...        [ON <对象类型> <对象名>]       TO <用户>[,<用户>]...       [WITH GRANT OPTION];

Semantics: assigns the specified action permission to the specified action object to the specified user

GRANT

Issue Grant:
Dba
Database Object Creator (that is, master owner)
Users who have this permission

By a privileged user
One or more specific users
Public (all users)
With GRANT OPTION clause:
Specify: can be granted again
Not specified: Cannot propagate

 [例1] 把查询Student表权限授给用户U1      GRANT   SELECT       ON   TABLE   Student       TO   U1;

[例2] 把对Student表和Course表的全部权限授予用户U2和U3      GRANT ALL PRIVILIGES       ON TABLE Student, Course       TO U2, U3;

[例3] 把对表SC的查询权限授予所有用户     GRANT SELECT      ON TABLE SC       TO PUBLIC;

[例4] 把查询Student表和修改学生学号的权限授给用户U4　         GRANT UPDATE(Sno), SELECT         ON TABLE Student         TO U4;

insert  permission granted to U5 user, and allows him to grant this permission to other users grant  insert  on  table  SC to  U5 with  GRANT  option ;   

执行例5后，U5不仅拥有了对表SC的INSERT权限， 还可以传播此权限： [例6] GRANT INSERT ON TABLE SC TO U6        WITH GRANT OPTION;GRANT INSERT ON TABLE SC TO U7;  但U7不能再传播此权限。

Second, REVOKE
The granted permission can be retracted by the DBA or other grantee with the REVOKE statement

REVOKE语句的一般格式为：      REVOKE <权限>[,<权限>]...       [ON <对象类型> <对象名>]      FROM <用户>[,<用户>]...;

[例8] 把用户U4修改学生学号的权限收回        UPDATE(Sno)        ON TABLE Student         FROM U4;

[例9] 收回所有用户对表SC的查询权限        SELECT         ON TABLE SC         FROM PUBLIC;

Database-Authorization and recovery security