| Oracle® Database Security Guide 10g Release 1 (10.1) Part Number B10773-01 |
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| Oracle® Database Security Guide 10g Release 1 (10.1) Part Number B10773-01 |
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View PDF |
Many tasks, with many interwoven considerations, are involved in administering user privileges, roles, and profiles. These necessary operations and principles are discussed in the following sections:
| Topic Category | Links to Topics |
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Managing Privileges, Roles, and Profiles |
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Granting, Revoking, and Viewing |
Each Oracle database has a list of valid database users. To access a database, a user must run a database application and connect to the database instance using a valid user name defined in the database. This section explains how to manage users for a database, and contains the following topics:
| See Also:
Oracle Database SQL Reference for more information about SQL statements used for managing users |
You create a database user with the CREATE USER statement.To create a user, you must have the CREATE USER system privilege. Because it is a powerful privilege, a DBA or security administrator is normally the only user who has the CREATE USER system privilege.
The following example creates a user and specifies that user's password, default tablespace, temporary tablespace where temporary segments are created, tablespace quotas, and profile.
CREATE USER jward IDENTIFIED BY AZ7BC2 DEFAULT TABLESPACE data_ts QUOTA 100M ON test_ts QUOTA 500K ON data_ts TEMPORARY TABLESPACE temp_ts PROFILE clerk; GRANT create session TO jward;
A newly created user cannot connect to the database until granted the CREATE SESSION system privilege.
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Note: As administrator, you should create your own roles and assign only those privileges that are needed. For example, it is unwise to grant CONNECT if all that is needed is CREATE SESSION, since CONNECT includes several additional privileges: see Table 10-1. Creating its own roles gives an organization detailed control of the privileges it assigns, and protects it in case Oracle were to change or remove roles that it defines. |
This section refers to the preceding example as it discusses the following aspects of creating a user:
Within each database a user name must be unique with respect to other user names and roles. A user and role cannot have the same name. Furthermore, each user has an associated schema. Within a schema, each schema object must have a unique name.
In the previous CREATE USER statement, the new user is to be authenticated using the database. In this case, the connecting user must supply the correct password to the database to connect successfully.
Selecting and specifying the method of user authentication is discussed in "User Authentication Methods".
Each user should have a default tablespace. When a user creates a schema object and specifies no tablespace to contain it, Oracle stores the object in the user's default tablespace.
The default setting for every user's default tablespace is the SYSTEM tablespace. If a user does not create objects, and has no privileges to do so, this default setting is fine. However, if a user is likely to create any type of object, you should specifically assign the user a default tablespace. Using a tablespace other than SYSTEM reduces contention between data dictionary objects and user objects for the same datafiles. In general, it is not advisable for user data to be stored in the SYSTEM tablespace.
You can create a permanent default tablespace other than SYSTEM at the time of database creation, to be used as the database default for permanent objects. By separating the user data from the system data, you reduce the likelihood of problems with the SYSTEM tablespace, which can in some circumstances cause the entire database to become non-functional. This default permanent tablespace is not used by system users, that is, SYS, SYSTEM, and OUTLN, whose default permanent tablespace remains SYSTEM. A tablespace designated as the default permanent tablespace cannot be dropped; to accomplish this goal, another tablespace must first be designated as the default permanent tablespace. It is possible to ALTER the default permanent tablespace to another tablespace, affecting all users/objects created after the ALTER DDL commits.
You can also set a user's default tablespace during user creation, and change it later with the ALTER USER statement. Changing the user's default tablespace affects only objects created after the setting is changed.
When you specify the user's default tablespace, also specify a quota on that tablespace.
In the previous CREATE USER statement, jward's default tablespace is data_ts, and his quota on that tablespace is 500K.
You can assign each user a tablespace quota for any tablespace (except a temporary tablespace). Assigning a quota does two things:
By default, a user has no quota on any tablespace in the database. If the user has the privilege to create a schema object, you must assign a quota to allow the user to create objects. Minimally, assign users a quota for the default tablespace, and additional quotas for other tablespaces in which they can create objects.
You can assign a user either individual quotas for a specific amount of disk space in each tablespace or an unlimited amount of disk space in all tablespaces. Specific quotas prevent a user's objects from consuming too much space in the database.
You can assign a user's tablespace quotas when you create the user, or add or change quotas later. If a new quota is less than the old one, then the following conditions hold true:
You can revoke a user's ability to create objects in a tablespace by changing the user's current quota to zero. After a quota of zero is assigned, the user's objects in the tablespace remain, but new objects cannot be created and existing objects cannot be allocated any new space.
To permit a user to use an unlimited amount of any tablespace in the database, grant the user the UNLIMITED TABLESPACE system privilege. This overrides all explicit tablespace quotas for the user. If you later revoke the privilege, explicit quotas again take effect. You can grant this privilege only to users, not to roles.
Before granting the UNLIMITED TABLESPACE system privilege, consider the consequences of doing so.
Advantage:
Disadvantages:
UNLIMITED TABLESPACE privilege. You can grant access selectively only after revoking the privilege.Each user also should be assigned a temporary tablespace. When a user executes a SQL statement that requires a temporary segment, Oracle stores the segment in the user's temporary tablespace. These temporary segments are created by the system when doing sorts or joins and are owned by SYS, which has resource privileges in all tablespaces.
In the previous CREATE USER statement, jward's temporary tablespace is temp_ts, a tablespace created explicitly to contain only temporary segments. Such a tablespace is created using the CREATE TEMPORARY TABLESPACE statement.
If a user's temporary tablespace is not explicitly set, the user is assigned the default temporary tablespace that was specified at database creation, or by an ALTER DATABASE statement at a later time. If there is no default temporary tablespace explicitly assigned, the default is the SYSTEM tablespace or another permanent default established by the system administrator. It is not advisable for user data to be stored in the SYSTEM tablespace. Also, assigning a tablespace to be used specifically as a temporary tablespace eliminates file contention among temporary segments and other types of segments.
You can set a user's temporary tablespace at user creation, and change it later using the ALTER USER statement. Do not set a quota for temporary tablespaces. You can also establish tablespace groups instead of assigning individual temporary tablespaces.
| See Also:
These sections in Oracle Database Administrator's Guide:, Chapter 8, Managing Tablespaces: |
You also specify a profile when you create a user. A profile is a set of limits on database resources and password access to the database. If no profile is specified, the user is assigned a default profile.
You cannot set a user's default roles in the CREATE USER statement. When you first create a user, the user's default role setting is ALL, which causes all roles subsequently granted to the user to be default roles. Use the ALTER USER statement to change the user's default roles.
Users can change their own passwords. However, to change any other option of a user's security domain, you must have the ALTER USER system privilege. Security administrators are normally the only users that have this system privilege, as it allows a modification of any user's security domain. This privilege includes the ability to set tablespace quotas for a user on any tablespace in the database, even if the user performing the modification does not have a quota for a specified tablespace.
You can alter a user's security settings with the ALTER USER statement. Changing a user's security settings affects the user's future sessions, not current sessions.
The following statement alters the security settings for user avyrros:
ALTER USER avyrros IDENTIFIED EXTERNALLY DEFAULT TABLESPACE data_ts TEMPORARY TABLESPACE temp_ts QUOTA 100M ON data_ts QUOTA 0 ON test_ts PROFILE clerk;
The ALTER USER statement here changes avyrros's security settings as follows:
avyrros's operating system account.avyrros's default and temporary tablespaces are explicitly set.avyrros is given a 100M quota for the data_ts tablespace.avyrros's quota on the test_ts is revoked.avyrros is assigned the clerk profile.Most non-DBA users can still change their own passwords with the ALTER USER statement, as follows:
ALTER USER andy IDENTIFIED BY swordfish;
No special privileges (other than those to connect to the database) are required for a user to change passwords. Users should be encouraged to change their passwords frequently.
Users must have the ALTER USER privilege to switch between methods of authentication. Usually, only an administrator has this privilege.
| See Also:
"User Authentication Methods" for information about the authentication methods that are available for Oracle users |
A default role is one that is automatically enabled for a user when the user creates a session. You can assign a user zero or more default roles.
When a user is dropped, the user and associated schema are removed from the data dictionary and all schema objects contained in the user's schema, if any, are immediately dropped.
A user that is currently connected to a database cannot be dropped. To drop a connected user, you must first terminate the user's sessions using the SQL statement ALTER SYSTEM with the KILL SESSION clause.
You can drop a user from a database using the DROP USER statement. To drop a user and all the user's schema objects (if any), you must have the DROP USER system privilege. Because the DROP USER system privilege is so powerful, a security administrator is typically the only type of user that has this privilege.
If the user's schema contains any schema objects, use the CASCADE option to drop the user and all associated objects and foreign keys that depend on the tables of the user successfully. If you do not specify CASCADE and the user's schema contains objects, an error message is returned and the user is not dropped. Before dropping a user whose schema contains objects, thoroughly investigate which objects the user's schema contains and the implications of dropping them. Pay attention to any unknown cascading effects. For example, if you intend to drop a user who owns a table, check whether any views or procedures depend on that particular table.
The following statement drops user jones and all associated objects and foreign keys that depend on the tables owned by jones.
DROP USER jones CASCADE;
| See Also:
"Terminating Sessions" in Oracle Database Administrator's Guide for more information about terminating sessions |
The wide variety of options for viewing such information is discussed in the following subsections:
The following data dictionary views contain information about database users and profiles:
The following sections present some example of using these views, and assume a database in which the following statements have been executed:
CREATE PROFILE clerk LIMIT SESSIONS_PER_USER 1 IDLE_TIME 30 CONNECT_TIME 600; CREATE USER jfee IDENTIFIED BY wildcat DEFAULT TABLESPACE users TEMPORARY TABLESPACE temp_ts QUOTA 500K ON users PROFILE clerk; CREATE USER dcranney IDENTIFIED BY bedrock DEFAULT TABLESPACE users TEMPORARY TABLESPACE temp_ts QUOTA unlimited ON users; CREATE USER userscott IDENTIFIED BY scott1;
| See Also:
Oracle Database SQL Reference for complete descriptions of the preceding data dictionary and dynamic performance views |
The following query lists users and their associated information as defined in the database:
SELECT USERNAME, PROFILE, ACCOUNT_STATUS FROM DBA_USERS; USERNAME PROFILE ACCOUNT_STATUS --------------- --------------- --------------- SYS DEFAULT OPEN SYSTEM DEFAULT OPEN USERSCOTT DEFAULT OPEN JFEE CLERK OPEN DCRANNEY DEFAULT OPEN
All passwords are encrypted to preserve security. If a user queries the PASSWORD column, that user is not able to determine another user's password.
The following query lists all tablespace quotas specifically assigned to each user:
SELECT * FROM DBA_TS_QUOTAS; TABLESPACE USERNAME BYTES MAX_BYTES BLOCKS MAX_BLOCKS ---------- --------- -------- ---------- ------- ---------- USERS JFEE 0 512000 0 250 USERS DCRANNEY 0 -1 0 -1
When specific quotas are assigned, the exact number is indicated in the MAX_BYTES column. Note that this number is always a multiple of the database block size, so if you specify a tablespace quota that is not a multiple of the database block size, it is rounded up accordingly. Unlimited quotas are indicated by "-1".
The following query lists all profiles in the database and associated settings for each limit in each profile:
SELECT * FROM DBA_PROFILES ORDER BY PROFILE; PROFILE RESOURCE_NAME RESOURCE LIMIT ----------------- --------------- ---------- -------------- CLERK COMPOSITE_LIMIT KERNEL DEFAULT CLERK FAILED_LOGIN_ATTEMPTS PASSWORD DEFAULT CLERK PASSWORD_LIFE_TIME PASSWORD DEFAULT CLERK PASSWORD_REUSE_TIME PASSWORD DEFAULT CLERK PASSWORD_REUSE_MAX PASSWORD DEFAULT CLERK PASSWORD_VERIFY_FUNCTION PASSWORD DEFAULT CLERK PASSWORD_LOCK_TIME PASSWORD DEFAULT CLERK PASSWORD_GRACE_TIME PASSWORD DEFAULT CLERK PRIVATE_SGA KERNEL DEFAULT CLERK CONNECT_TIME KERNEL 600 CLERK IDLE_TIME KERNEL 30 CLERK LOGICAL_READS_PER_CALL KERNEL DEFAULT CLERK LOGICAL_READS_PER_SESSION KERNEL DEFAULT CLERK CPU_PER_CALL KERNEL DEFAULT CLERK CPU_PER_SESSION KERNEL DEFAULT CLERK SESSIONS_PER_USER KERNEL 1 DEFAULT COMPOSITE_LIMIT KERNEL UNLIMITED DEFAULT PRIVATE_SGA KERNEL UNLIMITED DEFAULT SESSIONS_PER_USER KERNEL UNLIMITED DEFAULT CPU_PER_CALL KERNEL UNLIMITED DEFAULT LOGICAL_READS_PER_CALL KERNEL UNLIMITED DEFAULT CONNECT_TIME KERNEL UNLIMITED DEFAULT IDLE_TIME KERNEL UNLIMITED DEFAULT LOGICAL_READS_PER_SESSION KERNEL UNLIMITED DEFAULT CPU_PER_SESSION KERNEL UNLIMITED DEFAULT FAILED_LOGIN_ATTEMPTS PASSWORD UNLIMITED DEFAULT PASSWORD_LIFE_TIME PASSWORD UNLIMITED DEFAULT PASSWORD_REUSE_MAX PASSWORD UNLIMITED DEFAULT PASSWORD_LOCK_TIME PASSWORD UNLIMITED DEFAULT PASSWORD_GRACE_TIME PASSWORD UNLIMITED DEFAULT PASSWORD_VERIFY_FUNCTION PASSWORD UNLIMITED DEFAULT PASSWORD_REUSE_TIME PASSWORD UNLIMITED 32 rows selected.
The following query lists all current sessions, showing the Oracle user and current UGA (user global area) memory use for each session:
SELECT USERNAME, VALUE || 'bytes' "Current UGA memory" FROM V$SESSION sess, V$SESSTAT stat, V$STATNAME name WHERE sess.SID = stat.SID AND stat.STATISTIC# = name.STATISTIC# AND name.NAME = 'session uga memory'; USERNAME Current UGA memory ------------------------------ --------------------------------------------- 18636bytes 17464bytes 19180bytes 18364bytes 39384bytes 35292bytes 17696bytes 15868bytes USERSCOTT 42244bytes SYS 98196bytes SYSTEM 30648bytes 11 rows selected.
To see the maximum UGA memory ever allocated to each session since the instance started, replace 'session uga memory' in the preceding query with 'session uga memory max'.
A profile is a named set of resource limits that restrict a user's database usage and instance resources, as well as password practices. For profiles to take effect, resource limits must be turned on for the database as a whole. You can assign a profile to each user, and a default profile to all others. Each user can have only one profile; creating a new one supersedes any earlier one.
However, in Oracle 10g, resource allocations and restrictions are primarily handled through the Database Resource Manager.
See Also:
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A profile can be created, assigned to users, altered, and dropped at any time (using CREATE USER or ALTER USER) by any authorized database user. Profiles can be assigned only to users and not to roles or other profiles. Such assignments do not affect current sessions. Profile resource limits are enforced only when you enable resource limitation for the associated database. Enabling such limitation can occur either before starting up the database (the RESOURCE_LIMIT initialization parameter) or while it is open (using an ALTER SYSTEM statement).
See Also:
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To drop a profile, you must have the DROP PROFILE system privilege. You can drop a profile (other than the default profile) using the SQL statement DROP PROFILE. To successfully drop a profile currently assigned to a user, use the CASCADE option.
The following statement drops the profile clerk, even though it is assigned to a user:
DROP PROFILE clerk CASCADE;
Any user currently assigned to a profile that is dropped is automatically assigned to the DEFAULT profile. The DEFAULT profile cannot be dropped. When a profile is dropped, the drop does not affect currently active sessions. Only sessions created after a profile is dropped abide by any modified profile assignments.
A user privilege is a right to execute a particular type of SQL statement, or a right to access another user's object, execute a PL/SQL package, and so on. The types of privileges are defined by Oracle.
Roles are created by users (usually administrators) to group together privileges or other roles. They are a means of facilitating the granting of multiple privileges or roles to users.
This section describes Oracle user privileges, and contains the following topics:
| See Also:
Oracle Database Concepts for additional information about privileges and roles |
There are over 100 distinct system privileges. Each system privilege allows a user to perform a particular database operation or class of database operations.
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Caution: System privileges can be very powerful, and should be granted only when necessary to roles and trusted users of the database. |
| See Also:
Oracle Database SQL Reference. for the complete list of system privileges and their descriptions |
Because system privileges are so powerful, Oracle recommends that you configure your database to prevent regular (non-DBA) users exercising ANY system privileges (such as UPDATE ANY TABLE) on the data dictionary. In order to secure the data dictionary, ensure that the O7_DICTIONARY_ACCESSIBILITY initialization parameter is set to FALSE, the default value. This feature is called the dictionary protection mechanism.
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Note: The When this parameter is not set to See the Oracle Database Reference for more information on the |
If you enable dictionary protection (O7_DICTIONARY_ACCESSIBILITY is FALSE), access to objects in the SYS schema (dictionary objects) is restricted to users with the SYS schema. These users are SYS and those who connect as SYSDBA. System privileges providing access to objects in other schemas do not give other users access to objects in the SYS schema. For example, the SELECT ANY TABLE privilege allows users to access views and tables in other schemas, but does not enable them to select dictionary objects (base tables of dynamic performance views, views, packages, and synonyms). These users can, however, be granted explicit object privileges to access objects in the SYS schema.
Users with explicit object privileges or those who connect with administrative privileges (SYSDBA) can access objects in the SYS schema. Another means of allowing access to objects in the SYS schema is by granting users any of the following roles:
SELECT_CATALOG_ROLE
This role can be granted to users to allow SELECT privileges on data dictionary views.
EXECUTE_CATALOG_ROLE
This role can be granted to users to allow EXECUTE privileges for packages and procedures in the data dictionary.
DELETE_CATALOG_ROLE
This role can be granted to users to allow them to delete records from the system audit table (AUD$).
Additionally, the following system privilege can be granted to users who require access to tables created in the SYS schema:
SELECT ANY DICTIONARY
This system privilege allows query access to any object in the SYS schema, including tables created in that schema. It must be granted individually to each user requiring the privilege. It is not included in GRANT ALL PRIVILEGES, nor can it be granted through a role.
Each type of object has different privileges associated with it.
You can specify ALL [PRIVILEGES] to grant or revoke all available object privileges for an object. ALL is not a privilege; rather, it is a shortcut, or a way of granting or revoking all object privileges with one word in GRANT and REVOKE statements. Note that if all object privileges are granted using the ALL shortcut, individual privileges can still be revoked.
Likewise, all individually granted privileges can be revoked by specifying ALL. However, if you REVOKE ALL, and revoking causes integrity constraints to be deleted (because they depend on a REFERENCES privilege that you are revoking), you must include the CASCADE CONSTRAINTS option in the REVOKE statement.
| See Also:
Oracle Database SQL Reference. for the complete list of object privileges |
A role groups several privileges and roles, so that they can be granted to and revoked from users simultaneously. A role must be enabled for a user before it can be used by the user.
Oracle provides some predefined roles to help in database administration. These roles, listed in Table 10-1, are automatically defined for Oracle databases when you run the standard scripts that are part of database creation. You can grant privileges and roles to, and revoke privileges and roles from, these predefined roles in the same way as you do with any role you define.
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Note: Each installation should create its own roles and assign only those privileges that are needed. For example, it is unwise to grant CONNECT if all that is needed is CREATE SESSION, since CONNECT includes several additional privileges: see Table 10-1. Creating its own roles gives an organization detailed control of the privileges it assigns, and protects it in case Oracle were to change or remove roles that it defines. |
If you install other options or products, other predefined roles may be created.
This section describes aspects of managing roles, and contains the following topics:
You can create a role using the CREATE ROLE statement, but you must have the CREATE ROLE system privilege to do so. Typically, only security administrators have this system privilege.
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Note: Immediately after creation, a role has no privileges associated with it. To associate privileges with a new role, you must grant privileges or other roles to the new role. |
You must give each role you create a unique name among existing usernames and role names of the database. Roles are not contained in the schema of any user. In a database that uses a multibyte character set, Oracle recommends that each role name contain at least one single-byte character. If a role name contains only multibyte characters, the encrypted role name/password combination is considerably less secure.
The following statement creates the clerk role, which is authorized by the database using the password bicentennial:
CREATE ROLE clerk IDENTIFIED BY bicentennial;
The IDENTIFIED BY clause specifies how the user must be authorized before the role can be enabled for use by a specific user to which it has been granted. If this clause is not specified, or NOT IDENTIFIED is specified, then no authorization is required when the role is enabled. Roles can be specified to be authorized by:
These authorizations are discussed in following sections.
Later, you can set or change the authorization method for a role using the ALTER ROLE statement. The following statement alters the clerk role to specify that the user must have been authorized by an external source before enabling the role:
ALTER ROLE clerk IDENTIFIED EXTERNALLY;
To alter the authorization method for a role, you must have the ALTER ANY ROLE system privilege or have been granted the role with the ADMIN OPTION.
See Also:
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The methods of authorizing roles are presented in this section. A role must be enabled for you to use it.
| See Also:
"When Do Grants and Revokes Take Effect?" for a discussion about enabling roles |
The use of a role authorized by the database can be protected by an associated password. If you are granted a role protected by a password, you can enable or disable the role by supplying the proper password for the role in a SET ROLE statement. However, if the role is made a default role and enabled at connect time, the user is not required to enter a password.
The following statement creates a role manager. When it is enabled, the password morework must be supplied.
CREATE ROLE manager IDENTIFIED BY morework;
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Note: In a database that uses a multibyte character set, passwords for roles must include only singlebyte characters. Multibyte characters are not accepted in passwords. See the Oracle Database SQL Reference for information about specifying valid passwords. |
The INDENTIFIED USING package_name clause lets you create an application role, which is a role that can be enabled only by applications using an authorized package. Application developers do not need to secure a role by embedding passwords inside applications. Instead, they can create an application role and specify which PL/SQL package is authorized to enable the role.
The following example indicates that the role admin_role is an application role and the role can only be enabled by any module defined inside the PL/SQL package hr.admin.
CREATE ROLE admin_role IDENTIFIED USING hr.admin;
When enabling the user's default roles at login as specified in the user's profile, no checking is performed for application roles.
The following statement creates a role named accts_rec and requires that the user be authorized by an external source before it can be enabled:
CREATE ROLE accts_rec IDENTIFIED EXTERNALLY;
Role authentication through the operating system is useful only when the operating system is able to dynamically link operating system privileges with applications. When a user starts an application, the operating system grants an operating system privilege to the user. The granted operating system privilege corresponds to the role associated with the application. At this point, the application can enable the application role. When the application is terminated, the previously granted operating system privilege is revoked from the user's operating system account.
If a role is authorized by the operating system, you must configure information for each user at the operating system level. This operation is operating system dependent.
If roles are granted by the operating system, you do not need to have the operating system authorize them also; this is redundant.
| See Also:
"Granting Roles Using the Operating System or Network" for more information about roles granted by the operating system |
If users connect to the database over Oracle Net, by default their roles cannot be authenticated by the operating system. This includes connections through a shared server configuration, as this connection requires Oracle Net. This restriction is the default because a remote user could impersonate another operating system user over a network connection.
If you are not concerned with this security risk and want to use operating system role authentication for network clients, set the initialization parameter REMOTE_OS_ROLES in the database's initialization parameter file to TRUE. The change will take effect the next time you start the instance and mount the database. The parameter is FALSE by default.
A role can be defined as a global role, whereby a (global) user can only be authorized to use the role by an enterprise directory service. You define the global role locally in the database by granting privileges and roles to it, but you cannot grant the global role itself to any user or other role in the database. When a global user attempts to connect to the database, the enterprise directory is queried to obtain any global roles associated with the user.
The following statement creates a global role:
CREATE ROLE supervisor IDENTIFIED GLOBALLY;
Global roles are one component of enterprise user security. A global role only applies to one database, but it can be granted to an enterprise role defined in the enterprise directory. An enterprise role is a directory structure which contains global roles on multiple databases, and which can be granted to enterprise users.
A general discussion of global authentication and authorization of users, and its role in enterprise user management, was presented earlier in "Global Authentication and Authorization".
| See Also:
Oracle Advanced Security Administrator's Guide and Oracle Internet Directory Administrator's Guide for information about enterprise user management and how to implement it |
In some cases, it may be appropriate to drop a role from the database. The security domains of all users and roles granted a dropped role are immediately changed to reflect the absence of the dropped role's privileges. All indirectly granted roles of the dropped role are also removed from affected security domains. Dropping a role automatically removes the role from all users' default role lists.
Because the creation of objects is not dependent on the privileges received through a role, tables and other objects are not dropped when a role is dropped.
You can drop a role using the SQL statement DROP ROLE. To drop a role, you must have the DROP ANY ROLE system privilege or have been granted the role with the ADMIN OPTION.
The following statement drops the role CLERK:
DROP ROLE clerk;
This section describes the granting of privileges and roles, and contains the following topics:
It is also possible to grant roles to a user connected through a middle tier or proxy. This is discussed in "Proxy Authentication and Authorization".
You can grant system privileges and roles to other users and roles using the GRANT statement. The following privileges are required:
ADMIN OPTION or have been granted the GRANT ANY PRIVILEGE system privilege.ADMIN OPTION or have been granted the GRANT ANY ROLE system privilege.
The following statement grants the system privilege CREATE SESSION and the accts_pay role to the user jward:
GRANT CREATE SESSION, accts_pay TO jward;
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Notes:
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A user or role that is granted a privilege or role specifying the WITH ADMIN OPTION clause has several expanded capabilities:
ADMIN OPTION.In the following statement, the security administrator grants the new_dba role to michael:
GRANT new_dba TO michael WITH ADMIN OPTION;
The user michael cannot only use all of the privileges implicit in the new_dba role, but can grant, revoke, or drop the new_dba role as deemed necessary. Because of these powerful capabilities, exercise caution when granting system privileges or roles with the ADMIN OPTION. Such privileges are usually reserved for a security administrator and rarely granted to other administrators or users of the system.
When a user creates a role, the role is automatically granted to the creator with the ADMIN OPTION
Oracle enables you to create a new user with the GRANT statement. If you specify a password using the IDENTIFIED BY clause, and the username/password does not exist in the database, a new user with that username and password is created. The following example creates ssmith as a new user while granting ssmith the CONNECT system privilege:
GRANT CONNECT TO ssmith IDENTIFIED BY p1q2r3;
You also use the GRANT statement to grant object privileges to roles and users. To grant an object privilege, you must fulfill one of the following conditions:
GRANT ANY OBJECT PRIVILEGE system privilege that enables you to grant and revoke privileges on behalf of the object owner.WITH GRANT OPTION clause was specified when you were granted the object privilege by its owner.
The following statement grants the SELECT, INSERT, and DELETE object privileges for all columns of the emp table to the users jfee and tsmith:
GRANT SELECT, INSERT, DELETE ON emp TO jfee, tsmith;
To grant all object privileges on the salary view to the user jfee, use the ALL keyword, as shown in the following example:
GRANT ALL ON salary TO jfee;
Specify WITH GRANT OPTION to enable the grantee to grant the object privileges to other users and roles. The user whose schema contains an object is automatically granted all associated object privileges with the GRANT OPTION. This special privilege allows the grantee several expanded privileges:
GRANT OPTION, or to any role in the database.The GRANT OPTION is not valid when granting an object privilege to a role. Oracle prevents the propagation of object privileges through roles so that grantees of a role cannot propagate object privileges received by means of roles.
The GRANT ANY OBJECT PRIVILEGE system privilege allows users to grant and revoke any object privilege on behalf of the object owner. This provides a convenient means for database and application administrators to grant access to objects in any schema without requiring that they connect to the schema. This eliminates the need to maintain login credentials for schema owners so that they can grant access to objects, and it reduces the number of connections required during configuration.
This system privilege is part of the Oracle supplied DBA role and is thus granted (with the ADMIN OPTION) to any user connecting AS SYSDBA (user SYS). As with other system privileges, the GRANT ANY OBJECT PRIVILEGE system privilege can only be granted by a user who possesses the ADMIN OPTION.
When you exercise the GRANT ANY OBJECT PRIVILEGE system privilege to grant an object privilege to a user, if you already possess the object privilege with the GRANT OPTION, then the grant is performed in the usual way. In this case, you become the grantor of the grant. If you do not possess the object privilege, then the object owner is shown as the grantor, even though you, with the GRANT ANY OBJECT PRIVILEGE system privilege, actually performed the grant.
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Note: The audit record generated by the GRANT statement will always show the real user who performed the grant. |
For example, consider the following. User adams possesses the GRANT ANY OBJECT PRIVILEGE system privilege. He does not possess any other grant privileges. He issues the following statement:
GRANT SELECT ON hr.employees TO blake WITH GRANT OPTION;
If you examine the DBA_TAB_PRIVS view, you will see that hr is shown as being the grantor of the privilege:
SQL> SELECT GRANTEE, OWNER, GRANTOR, PRIVILEGE, GRANTABLE 2> FROM DBA_TAB_PRIVS 3> WHERE TABLE_NAME = 'EMPLOYEES' and OWNER = 'HR'; GRANTEE OWNER GRANTOR PRIVILEGE GRANTABLE -------- ----- ------- ----------- ---------- BLAKE HR HR SELECT YES
Now assume that blake also has the GRANT ANY OBJECT PRIVILEGE system. He, issues the following statement:
GRANT SELECT ON hr.employees TO clark;
In this case, when you again query the DBA_TAB_PRIVS view, you see that blake is shown as being the grantor of the privilege:
GRANTEE OWNER GRANTOR PRIVILEGE GRANTABLE -------- ----- -------- -------- ---------- BLAKE HR HR SELECT YES CLARK HR BLAKE SELECT NO
This occurs because blake already possesses the SELECT privilege on hr.employees with the GRANT OPTION.
You can grant INSERT, UPDATE, or REFERENCES privileges on individual columns in a table.
The following statement grants INSERT privilege on the acct_no column of the accounts table to scott:
GRANT INSERT (acct_no) ON accounts TO scott;
In another example, object privilege for the ename and job columns of the emp table are granter to the users jfee and tsmith:
GRANT INSERT(ename, job) ON emp TO jfee, tsmith;
You can also provide access control at the row level, that is, within objects, using Virtual Private Database (VPD) or Oracle Label Security.
This section describes aspects of revoking user privileges and roles, and contains the following topics:
You can revoke system privileges and roles using the SQL statement REVOKE.
Any user with the ADMIN OPTION for a system privilege or role can revoke the privilege or role from any other database user or role. The revoker does not have to be the user that originally granted the privilege or role. Users with GRANT ANY ROLE can revoke any role.
The following statement revokes the CREATE TABLE system privilege and the accts_rec role from tsmith:
REVOKE CREATE TABLE, accts_rec FROM tsmith;
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Note: The |
The REVOKE statement is used to revoke object privileges. To revoke an object privilege, you must fulfill one of the following conditions:
GRANT ANY OBJECT PRIVILEGE system privilege that enables you to grant and revoke privileges on behalf of the object owner.You can only revoke the privileges that you, the grantor, directly authorized, not the grants made by other users to whom you granted the GRANT OPTION. However, there is a cascading effect. The object privilege grants propagated using the GRANT OPTION are revoked if a grantor's object privilege is revoked.
Assuming you are the original grantor, the following statement revokes the SELECT and INSERT privileges on the emp table from the users jfee and tsmith:
REVOKE SELECT, insert ON emp FROM jfee, tsmith;
The following statement revokes all object privileges for the dept table that you originally granted to the human_resource role
REVOKE ALL ON dept FROM human_resources;
The GRANT ANY OBJECT PRIVILEGE system privilege enables you to revoke any specified object privilege where the object owner is the grantor. This occurs when the object privilege is granted by the object owner, or on behalf of the owner by any user holding the GRANT ANY OBJECT PRIVILEGE system privilege.
In a situation where the object privilege has been granted by both the owner of the object and the user executing the REVOKE statement (who has both the specific object privilege and the GRANT ANY OBJECT PRIVILEGE system privilege), Oracle only revokes the object privilege granted by the user issuing the REVOKE. This can be illustrated by continuing the example started in "Granting Object Privileges on Behalf of the Object Owner".
At this point, blake has granted the SELECT privilege on hr.employees to clark. Even though blake possesses the GRANT ANY OBJECT PRIVILEGE system privilege, he also holds the specific object privilege, thus this grant is attributed to him. Assume that hr also grants the SELECT privilege on hr.employees to clark. A query of the DBA_TAB_PRIVS view shows that the following grants are in effect for the hr.employees table:
GRANTEE OWNER GRANTOR PRIVILEGE GRANTABLE -------- ----- ------- ----------- ---------- BLAKE HR HR SELECT YES CLARK HR BLAKE SELECT NO CLARK HR HR SELECT NO
User blake now issues the following REVOKE statement:
REVOKE SELECT ON hr.employees FROM clark;
Only the object privilege for clark granted by blake is removed. The grant by the object owner, hr, remains.
GRANTEE OWNER GRANTOR PRIVILEGE GRANTABLE -------- ----- ------- ----------- ---------- BLAKE HR HR SELECT YES CLARK HR HR SELECT NO
If blake issues the REVOKE statement again, this time the effect will be to remove the object privilege granted by hr.
Although users can grant column-selective INSERT, UPDATE, and REFERENCES privileges for tables and views, they cannot selectively revoke column specific privileges with a similar REVOKE statement. Instead, the grantor must first revoke the object privilege for all columns of a table or view, and then selectively re-grant the column-specific privileges that should remain.
For example, assume that role human_resources has been granted the UPDATE privilege on the deptno and dname columns of the table dept. To revoke the UPDATE privilege on just the deptno column, issue the following two statements:
REVOKE UPDATE ON dept FROM human_resources; GRANT UPDATE (dname) ON dept TO human_resources;
The REVOKE statement revokes UPDATE privilege on all columns of the dept table from the role human_resources. The GRANT statement re-grants UPDATE privilege on the dname column to the role human_resources.
If the grantee of the REFERENCES object privilege has used the privilege to create a foreign key constraint (that currently exists), the grantor can revoke the privilege only by specifying the CASCADE CONSTRAINTS option in the REVOKE statement:
REVOKE REFERENCES ON dept FROM jward CASCADE CONSTRAINTS;
Any foreign key constraints currently defined that use the revoked REFERENCES privilege are dropped when the CASCADE CONSTRAINTS clause is specified.
Depending on the type of privilege, there may be cascading effects when a privilege is revoked.
There are no cascading effects when revoking a system privilege related to DDL operations, regardless of whether the privilege was granted with or without the ADMIN OPTION. For example, assume the following:
CREATE TABLE system privilege to jfee with the ADMIN OPTION.jfee creates a table.jfee grants the CREATE TABLE system privilege to tsmith.tsmith creates a table.CREATE TABLE system privilege from jfee.jfee's table continues to exist. tsmith still has the table and the CREATE TABLE system privilege.Cascading effects can be observed when revoking a system privilege related to a DML operation. If SELECT ANY TABLE is revoked from a user, then all procedures contained in the users schema relying on this privilege will fail until the privilege is reauthorized.
Revoking an object privilege can have cascading effects that should be investigated before issuing a REVOKE statement.
test procedure includes a SQL statement that queries data from the emp table. If the SELECT privilege on the emp table is revoked from the owner of the test procedure, the procedure can no longer be executed successfully.REFERENCES privilege for a table is revoked from a user, any foreign key integrity constraints defined by the user that require the dropped REFERENCES privilege are automatically dropped. For example, assume that the user jward is granted the REFERENCES privilege for the deptno column of the dept table and creates a foreign key on the deptno column in the emp table that references the deptno column. If the references privilege on the deptno column of the dept table is revoked, the foreign key constraint on the deptno column of the emp table is dropped in the same operation.GRANT OPTION are revoked if a grantor's object privilege is revoked. For example, assume that user1 is granted the SELECT object privilege with the GRANT OPTION, and grants the SELECT privilege on emp to user2. Subsequently, the SELECT privilege is revoked from user1. This REVOKE is cascaded to user2 as well. Any objects that depended on user1's and user2's revoked SELECT privilege can also be affected, as described in previous bullet items.Object definitions that require the ALTER and INDEX DDL object privileges are not affected if the ALTER or INDEX object privilege is revoked. For example, if the INDEX privilege is revoked from a user that created an index on someone else's table, the index continues to exist after the privilege is revoked.
Privileges and roles can also be granted to and revoked from the user group PUBLIC. Because PUBLIC is accessible to every database user, all privileges and roles granted to PUBLIC are accessible to every database user.
Security administrators and database users should grant a privilege or role to PUBLIC only if every database user requires the privilege or role. This recommendation reinforces the general rule that at any given time, each database user should only have the privileges required to accomplish the group's current tasks successfully.
Revoking a privilege from PUBLIC can cause significant cascading effects. If any privilege related to a DML operation is revoked from PUBLIC (for example, SELECT ANY TABLE, UPDATE ON emp), all procedures in the database, including functions and packages, must be reauthorized before they can be used again. Therefore, exercise caution when granting and revoking DML-related privileges to PUBLIC.
See Also:
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Depending on what is granted or revoked, a grant or revoke takes effect at different times:
PUBLIC) are immediately observed.PUBLIC) are only observed when a current user session issues a SET ROLE statement to re-enable the role after the grant/revoke, or when a new user session is created after the grant/revoke.You can see which roles are currently enabled by examining the SESSION_ROLES data dictionary view.
During the session, the user or an application can use the SET ROLE statement any number of times to change the roles currently enabled for the session. You must already have been granted the roles that you name in the SET ROLE statement.The number of roles that can be concurrently enabled is limited by the initialization parameter MAX_ENABLED_ROLES.
This example enables the role clerk, which you have already been granted, and specifies the password.
SET ROLE clerk IDENTIFIED BY bicentennial;
You can disable all roles with the following statement:
SET ROLE NONE;
When a user logs on, Oracle enables all privileges granted explicitly to the user and all privileges in the user's default roles.
A user's list of default roles can be set and altered using the ALTER USER statement. The ALTER USER statement enables you to specify roles that are to be enabled when a user connects to the database, without requiring the user to specify the roles' passwords. The user must have already been directly granted the roles with a GRANT statement. You cannot specify as a default role any role managed by an external service including a directory service (external roles or global roles).
The following example establishes default roles for user jane:
ALTER USER jane DEFAULT ROLE payclerk, pettycash;
You cannot set a user's default roles in the CREATE USER statement. When you first create a user, the user's default role setting is ALL, which causes all roles subsequently granted to the user to be default roles. Use the ALTER USER statement to limit the user's default roles.
A user can enable as many roles as specified by the initialization parameter MAX_ENABLED_ROLES. All indirectly granted roles enabled as a result of enabling a primary role are included in this count. The database administrator can alter this limitation by modifying the value for this parameter. Higher values permit each user session to have more concurrently enabled roles, but these values also cause more memory to be used for each user session. This occurs because the PGA size requires four bytes for each role in each session. Determine the highest number of roles that will be concurrently enabled by any one user and use this value for the MAX_ENABLED_ROLES parameter.
This section describes aspects of granting roles through your operating system or network, and contains the following topics:
Instead of a security administrator explicitly granting and revoking database roles to and from users using GRANT and REVOKE statements, the operating system that operates Oracle can grant roles to users at connect time. Roles can be administered using the operating system and passed to Oracle when a user creates a session. As part of this mechanism, each user's default roles and the roles granted to a user with the ADMIN OPTION can be identified. Even if the operating system is used to authorize users for roles, all roles must be created in the database and privileges assigned to the role with GRANT statements.
Roles can also be granted through a network service.
The advantage of using the operating system to identify a user's database roles is that privilege management for an Oracle database can be externalized. The security facilities offered by the operating system control a user's privileges. This option may offer advantages of centralizing security for a number of system activities, such as the following situation:
The main disadvantage of using the operating system to identify a user's database roles is that privilege management can only be performed at the role level. Individual privileges cannot be granted using the operating system, but can still be granted inside the database using GRANT statements.
A secondary disadvantage of using this feature is that by default users cannot connect to the database through the shared server, or any other network connection, if the operating system is managing roles. However, you can change this default; see "Using Network Connections with Operating System Role Management".
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Note: The features described in this section are available only on some operating systems. See your operating system specific Oracle documentation to determine if you can use these features. |
To operate a database so that it uses the operating system to identify each user's database roles when a session is created, set the initialization parameter OS_ROLES to TRUE (and restart the instance, if it is currently running). When a user attempts to create a session with the database, Oracle initializes the user's security domain using the database roles identified by the operating system.
To identify database roles for a user, each Oracle user's operating system account must have operating system identifiers (these may be called groups, rights identifiers, or other similar names) that indicate which database roles are to be available for the user. Role specification can also indicate which roles are the default roles of a user and which roles are available with the ADMIN OPTION. No matter which operating system is used, the role specification at the operating system level follows the format:
ora_ID_ROLE[_[d][a]]
where:
ID has a definition that varies on different operating systems. For example, on VMS, ID is the instance identifier of the database; on MVS, it is the machine type; on UNIX, it is the system ID.
ROLE is the name of the database role.d is an optional character that indicates this role is to be a default role of the database user.a is an optional character that indicates this role is to be granted to the user with the ADMIN OPTION. This allows the user to grant the role to other roles only. Roles cannot be granted to users if the operating system is used to manage roles.
For example, an operating system account might have the following roles identified in its profile:
ora_PAYROLL_ROLE1 ora_PAYROLL_ROLE2_a ora_PAYROLL_ROLE3_d ora_PAYROLL_ROLE4_da
When the corresponding user connects to the payroll instance of Oracle, role3 and role4 are defaults, while role2 and role4 are available with the ADMIN OPTION.
When you use operating system managed roles, it is important to note that database roles are being granted to an operating system user. Any database user to which the operating system user is able to connect will have the authorized database roles enabled. For this reason, you should consider defining all Oracle users as IDENTIFIED EXTERNALLY if you are using OS_ROLES = TRUE, so that the database accounts are tied to the operating system account that was granted privileges.
If OS_ROLES is set to TRUE, the operating system completely manages the grants and revokes of roles to users. Any previous grants of roles to users using GRANT statements do not apply; however, they are still listed in the data dictionary. Only the role grants made at the operating system level to users apply. Users can still grant privileges to roles and users.
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Note: If the operating system grants a role to a user with the |
If OS_ROLES is set to TRUE, any role granted by the operating system can be dynamically enabled using the SET ROLE statement. This still applies, even if the role was defined to require a password or operating system authorization. However, any role not identified in a user's operating system account cannot be specified in a SET ROLE statement, even if a role has been granted using a GRANT statement when OS_ROLES = FALSE. (If you specify such a role, Oracle ignores it.)
When OS_ROLES = TRUE, a user can enable as many roles as specified by the initialization parameter MAX_ENABLED_ROLES.
If you choose to have the operating system to manage roles, by default users cannot connect to the database through the shared server. This restriction is the default because a remote user could impersonate another operating system user over a non-secure connection.
If you are not concerned with this security risk and want to use operating system role management with the shared server, or any other network connection, set the initialization parameter REMOTE_OS_ROLES in the database's initialization parameter file to TRUE. The change will take effect the next time you start the instance and mount the database. The default setting of this parameter is FALSE.
To access information about grants of privileges and roles, you can query the following data dictionary views:
Some examples of using these views follow. For these examples, assume the following statements have been issued:
CREATE ROLE security_admin IDENTIFIED BY honcho; GRANT CREATE PROFILE, ALTER PROFILE, DROP PROFILE, CREATE ROLE, DROP ANY ROLE, GRANT ANY ROLE, AUDIT ANY, AUDIT SYSTEM, CREATE USER, BECOME USER, ALTER USER, DROP USER TO security_admin WITH ADMIN OPTION; GRANT SELECT, DELETE ON SYS.AUD$ TO security_admin; GRANT security_admin, CREATE SESSION TO swilliams; GRANT security_admin TO system_administrator; GRANT CREATE SESSION TO jward; GRANT SELECT, DELETE ON emp TO jward; GRANT INSERT (ename, job) ON emp TO swilliams, jward;
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Oracle Database Reference for a detailed description of these data dictionary views |
The following query returns all system privilege grants made to roles and users:
SELECT * FROM DBA_SYS_PRIVS; GRANTEE PRIVILEGE ADM -------------- --------------------------------- --- SECURITY_ADMIN ALTER PROFILE YES SECURITY_ADMIN ALTER USER YES SECURITY_ADMIN AUDIT ANY YES SECURITY_ADMIN AUDIT SYSTEM YES SECURITY_ADMIN BECOME USER YES SECURITY_ADMIN CREATE PROFILE YES SECURITY_ADMIN CREATE ROLE YES SECURITY_ADMIN CREATE USER YES SECURITY_ADMIN DROP ANY ROLE YES SECURITY_ADMIN DROP PROFILE YES SECURITY_ADMIN DROP USER YES SECURITY_ADMIN GRANT ANY ROLE YES SWILLIAMS CREATE SESSION NO JWARD CREATE SESSION NO
The following query returns all the roles granted to users and other roles:
SELECT * FROM DBA_ROLE_PRIVS; GRANTEE GRANTED_ROLE ADM ------------------ ------------------------------------ --- SWILLIAMS SECURITY_ADMIN NO
The following query returns all object privileges (not including column-specific privileges) granted to the specified user:
SELECT TABLE_NAME, PRIVILEGE, GRANTABLE FROM DBA_TAB_PRIVS WHERE GRANTEE = 'JWARD'; TABLE_NAME PRIVILEGE GRANTABLE ----------- ------------ ---------- EMP SELECT NO EMP DELETE NO
To list all the column-specific privileges that have been granted, use the following query:
SELECT GRANTEE, TABLE_NAME, COLUMN_NAME, PRIVILEGE FROM DBA_COL_PRIVS; GRANTEE TABLE_NAME COLUMN_NAME PRIVILEGE ----------- ------------ ------------- -------------- SWILLIAMS EMP ENAME INSERT SWILLIAMS EMP JOB INSERT JWARD EMP NAME INSERT JWARD EMP JOB INSERT
The following query lists all roles currently enabled for the issuer:
SELECT * FROM SESSION_ROLES;
If swilliams has enabled the security_admin role and issues this query, Oracle returns the following information:
ROLE ------------------------------ SECURITY_ADMIN
The following query lists all system privileges currently available in the issuer's security domain, both from explicit privilege grants and from enabled roles:
SELECT * FROM SESSION_PRIVS;
If swilliams has the security_admin role enabled and issues this query, Oracle returns the following results:
PRIVILEGE ---------------------------------------- AUDIT SYSTEM CREATE SESSION CREATE USER BECOME USER ALTER USER DROP USER CREATE ROLE DROP ANY ROLE GRANT ANY ROLE AUDIT ANY CREATE PROFILE ALTER PROFILE DROP PROFILE
If the security_admin role is disabled for swilliams, the first query would have returned no rows, while the second query would only return a row for the CREATE SESSION privilege grant.
The DBA_ROLES data dictionary view can be used to list all roles of a database and the authentication used for each role. For example, the following query lists all the roles in the database:
SELECT * FROM DBA_ROLES; ROLE PASSWORD ---------------- -------- CONNECT NO RESOURCE NO DBA NO SECURITY_ADMIN YES
The ROLE_ROLE_PRIVS, ROLE_SYS_PRIVS, and ROLE_TAB_PRIVS data dictionary views contain information on the privilege domains of roles.
For example, the following query lists all the roles granted to the system_admin role:
SELECT GRANTED_ROLE, ADMIN_OPTION FROM ROLE_ROLE_PRIVS WHERE ROLE = 'SYSTEM_ADMIN'; GRANTED_ROLE ADM ---------------- ---- SECURITY_ADMIN NO
The following query lists all the system privileges granted to the security_admin role:
SELECT * FROM ROLE_SYS_PRIVS WHERE ROLE = 'SECURITY_ADMIN'; ROLE PRIVILEGE ADM ----------------------- ----------------------------- --- SECURITY_ADMIN ALTER PROFILE YES SECURITY_ADMIN ALTER USER YES SECURITY_ADMIN AUDIT ANY YES SECURITY_ADMIN AUDIT SYSTEM YES SECURITY_ADMIN BECOME USER YES SECURITY_ADMIN CREATE PROFILE YES SECURITY_ADMIN CREATE ROLE YES SECURITY_ADMIN CREATE USER YES SECURITY_ADMIN DROP ANY ROLE YES SECURITY_ADMIN DROP PROFILE YES SECURITY_ADMIN DROP USER YES SECURITY_ADMIN GRANT ANY ROLE YES
The following query lists all the object privileges granted to the security_admin role:
SELECT TABLE_NAME, PRIVILEGE FROM ROLE_TAB_PRIVS WHERE ROLE = 'SECURITY_ADMIN'; TABLE_NAME PRIVILEGE --------------------------- ---------------- AUD$ DELETE AUD$ SELECT
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