Bài giảng Cơ sở dữ liệu nâng cao Chapter 3 Managing security
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Chapter 2
Managing Security
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Users
• Users are database-level principals and are created to access resources
within a
database.
• User and Log-in names should match.
• Users can be added to any one or more of the
available database roles.
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Users vs. Login
• Logins:
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Be created at the instance level
Can be mapped to a Windows user account, a domain account, a Windows group, a domain
group, ..
Provide a user access to the SQL Server instance.
access to one or more databases.
Do not provide access to the objects contained within the database.
• Permissions to access database objects are at the database user level.
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SQL Server security
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A user passes through 2 stages of security in SQL Server
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Authentication – validates that a user can connect to a SQL Server instance (Login)
Authorization – permissions validation; controls the activities the user is allowed to perform in the SQL Server
database (User)
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SQL Server authentication
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Windows Authentication
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Windows performs the authentication
SQL Server trusts that authentication and provides access to the Windows accounts as configured.
Windows user and group accounts can be mapped to SQL Server
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SQL Server authentication
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SQL Server specific logins:
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Windows user account is not required
Password is passed across the network for authentication
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Password is encrypted automatically
The primary advantage of this authentication scheme:
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SQL Server can authenticate any login no matter how they may have authenticated to the Windows network.
This option is typically less secure because it gives access to any-one who has the SQL Server password, without
regard to his or her Windows identity.
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SQL Server authentication
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Adding a new login
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Create new user in Windows.
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Once the users exist in the Windows user list or the Windows domain, SQL Server can recognize them.
Add a new login to SQL Server.
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Use SSMS
Use T-SQL command
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SQL Server authentication
• Adding a New Windows Login
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Use SSMS
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SQL Server authentication
• Adding a New Login
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Use T-SQL command:
CREATE LOGIN [name] {WITH <options> | FROM <source>}
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Options: contain many options. The most important one is the PASSWORD option. (The other
possible options are DEFAULT_DATABASE, DEFAULT_LANGUAGE, and
CHECK_EXPIRATION.)
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Source:
• WINDOWS: the login will be mapped to an existing Windows user account
• CERTIFICATE: the name of the certificate to be associated with this login.
• ASYMMETRIC KEY: the name of the asymmetric key to be associated with this login.
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SQL Server authentication
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Ex 1: Create a new SQL Server login for “Mary”
USE sample;
CREATE LOGIN mary WITH PASSWORD = ‘password';
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Ex 2: Creates a new login for “Bob” on the server
USE sample;
CREATE LOGIN Bob from Windows;
• Remove an existing login: use the DROP LOGIN statement
Ex: DROP LOGIN [AughtEight\Bob];
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Schema
• Schemas are collections of database objects such as tables, views, and
• Permissions can be granted to individual schemas within a database,
procedures.
providing a
powerful way to manage permissions.
• It is not necessary to grant access to each object within a schema when granting
permission to the schema.
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Principal
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Principal are logins allow you to connect to SQL Server. There are effectively three types of logins or
server principals
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Windows domain login
Windows local login
SQL Server login
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Principal
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Windows-level principals
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Windows Domain Login
Windows local login
Windows group
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Principal
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SQL Server-level principals
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SQL Server login
SQL Server login mapped to a Windows login
SQL Server login mapped to a certificate
SQL Server login mapped to an asymmetric key
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Principal
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Database-level principals
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Database user
Database user mapped to SQL Server login
Database user mapped to a Windows login
Database user mapped to a certificate
Database user mapped to an asymmetric key
Database role
Application role
Public role
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Securable objects in SQL Server
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Server
Database
Schema
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Roles
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SQL server provides two roles
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Fixed server-level:
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have a serverwide scope
Used for administration tasks
Database-level roles:
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have a database-level scope
custom database-level roles can be created
Used for admin and security
Include the public
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The fixed server-level role
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sysadmin – Perform any activity in the server.
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The BUILTIN\Administrators group and the local administrator’s are sysadmin
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serveradmin – Change server-wide configuration options and shut down the server.
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securityadmin – Manage logins and their properties. They will be able to reset passwords for SQL
Server logins and GRANT, DENY, and Revoke permissions.
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processadmin – End processes running in an instance of SQL Server.
setupadmin – Add and remove linked servers.
bulkadmin – Run the BULK INSERT statement.
diskadmin – Manage disk files.
dbcreator – CREATE, ALTER, DROP, and restore any database.
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The fixed server-level role
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A user is assigned to a server role by means of a system sp:
sp_addsrvrolemember
[ @loginame = ] ‘login’,
[ @rolename = ] ‘role’
Ex: EXEC sp_addsrvrolemember ‘XPS\Lauren’, ‘sysadmin’
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sp_dropsrvrolemember to remove a login from a fixed server role
Ex: EXEC sp_dropsrvrolemember ‘XPS\Lauren’, ‘sysadmin’
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sp_helpsrvrole: Get a list of the fixed server roles
sp_srvrolepermission: get the specific permissions for each role
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The fixed database-level roles
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db_owner – Can drop the database as well as permission to perform all configuration and
maintenance tasks.
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db_security_admin – Can modify role membership and manage permissions.
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Please be careful when adding principals to this role; an unintended privilege escalation could result.
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db_accessadmin – Can add or remove database access for Windows logins, Windows groups, and
SQL Server logins.
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db_backupoperator – Can back up the database.
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db_denydatareader – Will deny permission in the database to read any data in the user tables.
db_ddladmin – Can run any Data Definition Language command.
db_datawriter – Can add, delete, or change data in all user tables.
db_datareader – Can read all data from all user tables.
db_denydatawriter – Will deny permission in the database to add, modify, or delete any data in the
user tables.
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The fixed database-level roles
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Setting Up Database User Accounts:
CREATE USER [LoginName] FOR LOGIN [LoginName
Ex:
USE master;
CREATE LOGIN [AughtEight\Bob] FROM WINDOWS;
USE AdventureWorks2008;
CREATE USER BillyBob FOR LOGIN [AughtEight\Bob]
WITH DEFAULT_SCHEMA = sales;
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The fixed database-level role
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A user is assigned to a server role by means of a system sp:
sp_addrolemember
[ @rolename = ] ‘role’,
[ @loginame = ] ‘login’,
Ex: sp_addrolemember ‘db_datareader’, ‘Carol’;
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sp_dropsrvrolemember to remove a login from a fixed server role
Ex: sp_droprolemember ‘db_datareader’, ‘Carol’;
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sp_helprolemember: Get a list of the fixed database roles
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Principal of least privilege
• Do not grant more permissions than necessary.
• Be familiar with what each specific permission enables a user to accomplish.
• Inadvertently elevated permissions can pose a significant security risk.
˛
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Authorization
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Only authorized users are able to execute statements or perform operations on an entity
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There are three Transact-SQL statements related to authorization:
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Grant gives a right right to perform an action
Deny explicitly denies a right
Revoke removes an existing grant or deny
Permissions are applied to the objects (tables, views, stored procs, etc.) in the database
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Permission
• Grant statement
GRANT action ON object TO principal WITH {options}
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Ex 1:
USE master
GRANT CREATE ANY DATABASE TO Ted;
GO
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Ex2:
USE Master
GRANT CREATE FUNCTION TO mary;
