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MODULE 3 DATABASE MANAGEMENTSection 3 Database Security

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TABLESPACE AND DATA FILLEFa

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TABLESPACE AND DATA FILLE

Tablespaces are made up of at least one datafile You cannot create a table space without creating

its initial datafile; you cannot create a datafile without an associated tablespace

Big file tablespaces must be locally managed Undo tablespaces are specialized to store

undo (rollback) data

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THE DATAFILE CLAUSE

When creating a tablespace with a user-managed file, specify a datafile name in the command

Each datafile must have a specified SIZE Exceptions: OMFs and named files that already exist

Omitting AUTOEXTEND and SIZE parameters results in AUTOEXTEND set to ON

Example:

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0THE EXTENT MANAGEMENT AND SEGMENT

SPACE MANAGEMENT CLAUSES

These clauses tell Oracle how to track the usage of blocks within each extent

Locally vs. dictionary-managed performance: Locally managed tablespaces store the map of

where extents are in datafiles in a rapid access bitmap, in the header of the datafile

Dictionary-managed tablespaces store this information in metadata, in the SYSTEM tablespace

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0THE EXTENT MANAGEMENT AND SEGMENT

SPACE MANAGEMENT CLAUSES

Deallocated extents return to free space list in data dictionary as a contiguous chunk of data blocks For these to be usable, the next object that

needs an extent must be that exact size (or smaller) extent

Otherwise, deallocated data blocks are passed over, and data blocks at the end of datafile are used Datafile grows faster than necessary

If there are contiguous deallocated extents, they aren’t seen as a chunk of space until coalesced Coalescence: combining of multiple adjacent free

extents into a single contiguous free extent Occurs periodically through the SMON background

process

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0THE EXTENT MANAGEMENT AND SEGMENT

SPACE MANAGEMENT CLAUSES

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0CREATING A DICTIONARY-MANAGED TABLESPACE

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Dictionary-managed tablespaces cause slower performance of DML commands Updates involve multiple tables behind the

scenes Locally managed tablespaces

reduce/eliminate the problem of unused free space gaps

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CREATING A DICTIONARY-MANAGED TABLESPACE

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SEGMENT TYPES AND THEIR USESFa

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TEMPORARY TABLESPACE

Temporary segments need a temporary tablespace Oracle recommends creating locally managed,

temporary tablespaces

You can also create multiple temporary tablespaces Require a tablespace group Group can be set as the default for the entire DB

Assign the user a default temporary tablespace:

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ALTER TABLESPACE COMMAND

Tasks you can handle with ALTER TABLESPACE: Change DEFAULT STORAGE settings for any

future objects created in (dictionary-managed) tablespace

Change the MINIMUM EXTENT size Change LOGGING to NOLOGGING and vice versa Change PERMANENT to TEMPORARY (vice versa) Change READ ONLY to READ WRITE (vice versa) Coalesce contiguous storage space Add a new datafile or temporary file Rename a datafile or temporary file Begin and end an open backup

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ALTER TABLESPACE COMMAND

To change an existing datafile’s storage, you must use the ALTER DATABASE command instead:

To modify tempfile: ALTER DATABASE TEMPFILE

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ALTER TABLESPACE COMMAND

The status of a tablespace defines its availability to end-users and also defines how it is handled during backup and recovery ONLINE OFFLINE

NORMAL

TEMPORARY IMMEDIATE

It is possible to take individual datafiles offline

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READ-ONLY TABLESPACEFa

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DROPPING & RENAMING TABLESPACES

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TABLESPACE VIEWSFa

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DATA INTEGRITY

Database structure integrity Index corruption, data block corruption Invalid objects Managing structural problems: DBMS utility

Semantic data integrity Entity integrity – primary key should be used Check constraint , rules in SQL Server –

validate data Trigger – a piece of code that is executed

automatically when a data modification happens

Referential integrity – establish the relationship between primary and foreign key columns

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ASPECTS OF DATABASE SECURITY Authorization – controlling access to data Authentication – restricting access to

legitimate users Auditing – ensuring accountability and

inspection Encryption – safeguarding key data in the

database Enterprise security – managing the security

of the entire organizational information structure beyond database itself

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AUTHORIZATION

Authorization – controlling access to data Policy issues – what info should be viewed Integrity issues – preventing unexpected

results Types of privileges

Data access – read, write, or reference to a table, a view

Database object – create or modify database objects

System – perform certain types of system-wide activities

Procedure – execute specific functions and stored procedures

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AUTHORIZATION IMPLEMENTATION

Data Control Language (DCL) – Grant and Revoke

Grant different types of privileges GRANT SELECT, INSERT on Titles to user5; GRANT CREATE session, CREATE table to user1; GRANT SELECT ANY table to user9; GRANT EXECUTE on Proc1 to user2, user5;

Grant with GRANT option – pass the granted authority to others GRANT SELECT on Titles to user3 WITH GRANT

OPTION;

Revoke REVOKE INSERT on Titles from user5;

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ROLE AND GROUP

Roles – a collection of granted privileges A role can be created using the CREATE ROLE. The permissions are granted to the role The role is assigned to users using GRANT. These

users will get all the privileges from the role. Groups – DBMS built-in roles

System administrator: SYS in Oracle, SA in SQL Server

Database administrator: all privileges over the database

Operations control: perform certain operations such as backup and recovery

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AUTHENTICATION

Authentication – restricting access to legitimate users

DBMS user ID and password Password guidance and enforcement

Operating system login ID and password

LDAP authentication A global login account is established for

enterprise access In order to access a database, the global

login account has to be associated with the database.

It is a single sign-on or with same login and password

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AUDITING

Auditing – ensuring accountability and inspection

When auditing is enabled, the DBMS will produce an audit trail of database operations.

Auditing level – database, user, object Auditing issues – performance

degradation, storage usage Examples of audit facilities

Login and logoff attempts Commands issued to an object Stored procedure executions

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ENCRYPTION

Encryption – protect sensitive data in the database

It is a security technique that encodes legible data into a scrambled format.

Encryption consists of applying an encryption algorithm to data using some pre-specified encryption key. The resulting data has to be decrypted using a decryption key to recover the original data.

Examples of encryption Public key encryption Digital signature

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ENTERPRISE SECURITY

Enterprise security – managing the security of the entire organizational information structure beyond database itself

System-related issues: Operating system, database physical files, network access and control

Legal and ethical issues

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MODULE 3 DATABASE MANAGEMENTSection 4 User Management and Security in Oracle

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USER MANAGEMENT Creating a new user

Privilege required: “create user” system privilege SQL> CREATE USER mobeydick IDENTFIEDY BY

whitewhale;

Altering a user – modifying password, assign resource, etc. Privilege required: “alter user” system privilege SQL> ALTER USER Jim IDENTIFIED BY red; SQL> ALTER USER Jim DEFAULT TABLESPACE users;

Resource Default tablespace, temporary tablespace Profile: limit on the amount of resources a user can

use

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CREATE USERFa

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ALTER USERFa

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DROP USERFa

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Removing users requires the DROP USER system privilege, which the SYSTEM user has.DROP USER <user> CASCADE; Use CASCADE if user owns tables or DB objects

If a user has created other users, those users are not dropped when the creating user is dropped The new users do not belong to the original

user’s schema If a user has created tables you want to keep,

do not drop the user Instead, change the user account to LOCK status

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PROFILES

Specify a profile when you create/alter a DB user

Profile: collection of settings that limits the use of system resources and the database A profile can be assigned to any number of users

A user can be assigned only one profile at a time A newly assigned profile overrides the old one

User’s current session isn’t affected by profile change

DEFAULT profile has no resource or DB use limits As a system grows, resources may become stretched

Profiles can be used for managing passwords too

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CREATE PROFILE

CREATE PROFILE <profile> LIMIT<password_setting> ...<resource_setting> <limit> ...;

Password settings: FAILED_LOGIN_ATTEMPTS, PASSWORD_LIFE_TIME,

PASSWORD_REUSE_TIME, PASSWORD_REUSE_MAX, PASSWORD_LOCK_TIME, FAILED_LOGIN_ATTEMPTS, PASSWORD_GRACE_TIME, PASSWORD_VERIFY_FUNCTION

You can limit nine resources: SESSSIONS_PER_USER, CPU_PER_SESSION,

CPU_PER_CALL, CONNECT_TIME, IDLE_TIME, LOGICAL_READS_PER_SESSION, LOGICAL_READS_PER_CALL, PRIVATE_SGA, COMPOSITE_LIMIT

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PASSWORD MANAGEMENT

There are three different areas to examine when working with passwords: Changing a password and making it expire Enforcing password time limits, history, and

other settings Enforcing password complexity

Uses a combination of a function and a profile Predefined SQL script to verify the complexity of a

password Adjust the PASSWORD_VERIFY_FUNCTION setting in

a profile and assign that profile to a user

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ALTER PROFILE

ALTER PROFILE, with resource clauses listed:ALTER PROFILE <profile> LIMIT<password_setting> ...SESSIONS_PER_USER <concurrent sessions>CPU_PER_SESSION <hundredths of seconds>CPU_PER_CALL <hundredths of seconds>CONNECT_TIME <minutes>IDLE_TIME <minutes>LOGICAL_READS_PER_SESSION <data blocks>LOGICAL_READS_PER_CALL <data blocks>PRIVATE_SGA <bytes>COMPOSITE_LIMIT <service units>

Example:ALTER SYSTEM SET RESOURCE_LIMIT=TRUE;ALTER PROFILE PROGRAMMER LIMITIDLE_TIME 15CPU_PER_CALL 100;

ALTER RESOURCE COSTCPU_PER_SESSION 1000PRIVATE_SGA 1;

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DROP PROFLE

The syntax of DROP PROFILE is similar to the syntax for dropping a user in that it includes a CASCADE parameter:DROP PROFILE <profile> CASCADE;

You must add CASCADE if any users have been assigned the profile being dropped Oracle automatically resets these users to the

DEFAULT profile For example, if three users have been

assigned to the ACCT_MGR profile, drop the profile like this:DROP PROFILE ACCT_MGR CASCADE;

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ORACLE PRIVILEGES

In oracle, there are two types of privileges: system and object.

System privilege - allowing a user to perform a particular action within the database, or on any schema objects

Object privilege - gives user ability to perform some operations on a specific object such as table, view, procedure, function.

A role is a named group of collected system and object privileges.

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SYSTEM PRIVILEGE

System privilege - allowing a user to perform a particular action within the database, or on any schema objects

Privilege required: the system privilege with ADMIN OPTION, or GRANT ANY PRIVILEGE system privilege

Examples: CREATE SESSION: connect to a database CREATE ANY INDEX, SELECT ANY TABLE

Information is stored in: dba_sys_privs

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OBJECT PRIVILEGE

Object privilege - gives user ability to perform some operations on a specific object such as table, view, procedure, function

Privilege required: the owner of the object, object privileges with the GRANT option, GRANT ANY OBJECT system privilege

Examples: GRANT SELECT, INSERT ON Titles to user1;

Information is stored in: dba_tab_privs

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OBJECT PRIVILEGESFa

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ORACLE NAMING CONVENTION

In Oracle data dictionary, most object names begin with one of three prefixes:

USER_ information about objects owned by the user performing the query

ALL_ information from USER plus other objects on which privileges have been granted to PUBLIC or to the user

DBA_ all database objects, regardless of owner

Oracle dynamic views: current instance information

V$ v$session contains info of all current sessions

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ROLESFa

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DATA DICTIONARY VIEWSFa

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0EXAMPLES OF DATA DICTIONARY VIEWS DBA_USERS – information about all user

accounts DBA_ROLES – all the roles in the database USER_TAB_PRIVS – table privileges for

which you are the grantee, the grantor, or the object owner

USER_SYS_PRIVS – system privileges that have been granted to the user

USER_ROLE_PRIVS – roles that have been assigned to the user

SESSION_PRIVS – system privileges currently enabled for the login user

SESSION_ROLES – roles currently enabled for the user

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MIDTERM REVIEW DBA roles and responsibilities DBMS architecture and selection drivers Oracle architecture

database vs. instance logical and physical structures high-level understand background processes and memory

structure DBMS installation basics, change consideration Database design: conceptual, logical, and physical design Database connectivity layers, ODBC/JDBC architecture Oracle Net, Listener, purposes of “listener.ora” and

“tnsnames.ora” Database change: types, impacts, and management Database high-availability problems and solutions Database security: aspects, authorization, authentication Oracle privileges: system and object, roles

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