The DBMS_FGA package provides fine-grained security functions.
This chapter contains the following topics:
Security Model
Operational Notes
You must have the AUDIT_ADMIN role and the EXECUTE privilege on the DBMS_FGA package to administer audit policies. Because the audit function can potentially capture all user environment and application context values, policy administration should be executable by privileged users only. The policy event handler module will be executed with the module owner's privilege.
This package is available for only cost-based optimization. The rule-based optimizer may generate unnecessary audit records since audit monitoring can occur before row filtering. For both the rule-based optimizer and the cost-based optimizer, you can query the SQL_TEXT and SQL_BINDS columns of the UNIFIED_AUDIT_TRAIL view to analyze the SQL text and corresponding bind variables that are issued.
Table 67-1 DBMS_FGA Package Subprograms
| Subprogram | Description |
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Creates an audit policy using the supplied predicate as the audit condition |
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Disables an audit policy |
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Drops an audit policy |
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Enables an audit policy |
This procedure creates an audit policy using the supplied predicate as the audit condition. The maximum number of FGA policies on any table or view object is 256.
DBMS_FGA.ADD_POLICY( object_schema IN VARCHAR2 DEFAULT NULL, object_name IN VARCHAR2, policy_name IN VARCHAR2, audit_condition IN VARCHAR2 DEFAULT NULL, audit_column IN VARCHAR2 DEFAULT NULL, handler_schema IN VARCHAR2 DEFAULT NULL, handler_module IN VARCHAR2 DEFAULT NULL, enable IN BOOLEAN DEFAULT TRUE, statement_types IN VARCHAR2 DEFAULT SELECT, audit_trail IN BINARY_INTEGER DEFAULT NULL, audit_column_opts IN BINARY_INTEGER DEFAULT ANY_COLUMNS, policy_owner IN VARCHAR2 DEFAULT NULL);
Table 67-2 ADD_POLICY Procedure Parameters
| Parameter | Description |
|---|---|
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Schema of the object to be audited. If |
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Name of the object to be audited |
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Unique name of the policy |
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A condition in a row that indicates a monitoring condition. |
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Columns to be checked for access. These can include OLS hidden columns or object type columns. The default, |
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Schema that contains the event handler. The default, |
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Function name of the event handler; includes the package name if necessary. This function is invoked only after the first row that matches the audit condition in the query is processed. If the procedure fails with an exception, the user SQL statement will fail as well. |
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Enables the policy if |
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SQL statement types to which this policy is applicable: |
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In an environment that has not yet migrated to unified auditing, the destination (DB or XML) of fine-grained audit records. Also specifies whether to populate the |
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Establishes whether a statement is audited when the query references any column specified in the |
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User who owns the fine-grained auditing policy. However, this setting is not a user-supplied argument. The Oracle Data Pump client uses this setting internally to recreate the fine-grained audit policies appropriately. |
If object_schema is not specified, the current log-on user schema is assumed.
An FGA policy should not be applied to out-of-line columns such as LOB columns.
Each audit policy is applied to the query individually. However, at most one audit record may be generated for each policy, no matter how many rows being returned satisfy that policy's audit_condition. In other words, whenever any number of rows being returned satisfy an audit condition defined on the table, a single audit record will be generated for each such policy.
If a table with an FGA policy defined on it receives a Fast Path insert or a vectored update, the hint is automatically disabled before any such operations. Disabling the hint allows auditing to occur according to the policy's terms. (One example of a Fast Path insert is the statement INSERT-WITH-APPEND-hint.)
The audit_condition must be a boolean expression that can be evaluated using the values in the row being inserted, updated, or deleted. The expression can also use functions, such as the USER or SYS_CONTEXT functions.
The expression must not combine conditions using operators such as AND and OR. audit_condition can be NULL (or omitted), which is interpreted as TRUE, but it cannot contain the following elements:
Subqueries or sequences
The following attributes of the USERENV namespace when accessed using the SYS_CONTEXT function:
CURRENT_SQL
CURRENT_SQL_LENGTH
CURRENT_BIND
Any use of the pseudo columns LEVEL, PRIOR, or ROWNUM.
Specifying an audit condition of "1=1" to force auditing of all specified statements ("statement_types") affecting the specified column ("audit_column") is no longer needed to achieve this purpose. A NULL value for audit_condition causes audit to happen even if no rows are processed, so that all actions on a table with this policy are audited.
The audit_condition is evaluated using the privileges of the user who creates the policy.
For the audit_condition setting, do not include functions, which execute the auditable statement on the same base table, in the audit_condition setting. For example, suppose you create a function that executes an INSERT statement on the HR.EMPLOYEES table. The policy audit_condition contains this function and it is for INSERT statements (as set by the statement_types parameter). When the policy is used, the function executes recursively until the system has run out of memory. This can raise the error ORA-1000: maximum open cursors exceeded or ORA-00036: maximum number of recursive SQL levels (50) exceeded.
Do not issue the DBMS_FGA.ENABLE_POLICY or DBMS_FGA.DISABLE_POLICY statement from a policy function in a condition.
The audit function (handler_module) is an alerting mechanism for the administrator. The required interface for such a function is as follows:
PROCEDURE fname ( object_schema VARCHAR2, object_name VARCHAR2, policy_name VARCHAR2 ) AS ...
where fname is the name of the procedure, object_schema is the name of the schema of the table audited, object_name is the name of the table to be audited, and policy_name is the name of the policy being enforced. The audit function will be executed with the function owner's privilege.
If you have migrated to unified auditing, then omit the audit_trail parameter because the audit records will automatically be written to the unified audit trail.
Be aware that sensitive data, such as credit card information, can be recorded in clear text.
The audit_trail parameter, if used, specifies both where the fine-grained audit trail will be written and whether it is to include the query's SQL Text and SQL Bind variable information (typically in columns named LSQLTEXT and LSQLBIND):
If audit_trail includes XML, then fine-grained audit records are written to XML-format operating system files stored in the directory specified by an AUDIT_FILE_DEST statement in SQL. (The default AUDIT_FILE_DEST is $ORACLE_BASE/admin/$DB_UNIQUE_NAME/adump on Unix-based systems, and $ORACLE_BASE\admin\$DB_UNIQUE_NAME\adump on Windows systems.)
If audit_trail includes DB instead, then the audit records are written to the SYS.FGA_LOG$ table in the database. However, for read-only databases, Oracle Database writes the fine-grained audit records to XML files, regardless of the audit_trail settings.
If audit_trail includes EXTENDED, then the query's SQL Text and SQL Bind variable information are included in the audit trail.
For example:
Setting audit_trail to DBMS_FGA.DB sends the audit trail to the SYS.FGA_LOG$ table in the database and omits SQL Text and SQL Bind.
Setting audit_trail to DBMS_FGA.DB + DBMS_FGA.EXTENDED sends the audit trail to the SYS.FGA_LOG$ table in the database and includes SQL Text and SQL Bind.
Setting audit_trail to DBMS_FGA.XML writes the audit trail in XML files sent to the operating system and omits SQL Text and SQL Bind.
Setting audit_trail to DBMS_FGA.XML + DBMS_FGA.EXTENDED writes the audit trail in XML files sent to the operating system and includes SQL Text and SQL Bind.
The audit_trail parameter appears in the ALL_AUDIT_POLICIES view.
You can change the operating system destination using the following command:
ALTER SYSTEM SET AUDIT_FILE_DEST = New Directory DEFERRED
On many platforms, XML audit files are named process_name_processId.xml, for example, ora_2111.xml. Alternatively,l on Windows, the XML audit files are named process_name_ThreadId.xml (or process_name_ProcessId.xml if the process is not running as a thread).
The audit_column_opts parameter establishes whether a statement is audited
when the query references any column specified in the audit_column parameter (audit_column_opts = DBMS_FGA.ANY_COLUMNS), or
only when all such columns are referenced (audit_column_opts = DBMS_FGA.ALL_COLUMNS).
The default is DBMS_FGA.ANY_COLUMNS.
The ALL_AUDIT_POLICIES view also shows audit_column_opts.
When audit_column_opts is set to DBMS_FGA.ALL_COLUMNS, a SQL statement is audited only when all the columns mentioned in audit_column have been explicitly referenced in the statement. And these columns must be referenced in the same SQL-statement or in the sub-select.
All these columns must refer to a single table/view or alias.
If a SQL statement selects the columns from different table aliases, the statement will not be audited.
Every XML audit record contains the elements AUDIT_TYPE and EXTENDED_TIMESTAMP, with the latter printed in UTC zone (with no timezone information). Values retrieved using V$XML_AUDIT_TRAIL view are converted to session timezone and printed.
For SQL_TEXT and SQL_BIND element values (CLOB type columns), the dynamic view shows only the first 4000 characters. The underlying XML file may have more than 4000 characters for such SQL_TEXT and SQL_BIND values.
For large numbers of XML audit files, querying V$XML_AUDIT_TRAIL is faster when they are loaded into a database table using SQL*Loader or a similar tool. XML audit files are larger than the equivalent written to OS files when AUDIT_TRAIL=OS.
Error handling is the same as when AUDIT_TRAIL=OS. If any error occurs in writing an audit record to disk, including the directory identified by AUDIT_FILE_DEST being full, the auditing operation fails. An alert message is logged.
The policy event handler module will be executed with the module owner's privilege.
Do not create recursive fine-grained audit handlers. For example, suppose you create a handler that executes an INSERT statement on the HR.EMPLOYEES table. The policy that is associated with this handler is for INSERT statements (as set by the statement_types parameter). When the policy is used, the handler executes recursively until the system has run out of memory. This can raise the error ORA-1000: maximum open cursors exceeded or ORA-00036: maximum number of recursive SQL levels (50) exceeded. See also Oracle Database Security Guide with regard to Creating a Fine-Grained Audit Policy.
The values for the audit_trail parameter (XML and XML+EXTENDED) cause fine-grained auditing records to be written to operating system files in XML format. A dynamic view, V$XML_AUDIT_TRAIL, makes such audit records from XML files available to DBAs through SQL query, providing enhanced usability. Querying this view causes all XML files (all files with an.xml extension) in the AUDIT_FILE_DEST directory to be parsed and presented in relational table format.
Audit records stored in operating system files can be more secure than database-stored audit records because access can require file permissions that DBAs do not have. Operating system storage for audit records also offers higher availability, since such records remain available even if the database is temporarily inaccessible.
The DBA_COMMON_AUDIT_TRAIL view includes the contents of the V$XML_AUDIT_TRAIL dynamic view for standard and fine-grained audit records.
Note that the V$XML_AUDIT_TRAIL view is populated only if unified auditing is not enabled. If you have enabled unified auditing, then you can query the UNIFIED_AUDIT_TRAIL data dictionary view for the audit trail records.
See Also:
Oracle Database Security Guide for an example of creating an email alert handler for a fine-grained audit policyDBMS_FGA.ADD_POLICY ( object_schema => 'scott', object_name => 'emp', policy_name => 'mypolicy1', audit_condition => 'sal < 100', audit_column => 'comm,sal', handler_schema => NULL, handler_module => NULL, enable => TRUE, statement_types => 'INSERT, UPDATE', audit_column_opts => DBMS_FGA.ANY_COLUMNS, policy_owner => 'sec_admin);
This procedure disables an audit policy.
DBMS_FGA.DISABLE_POLICY( object_schema IN VARCHAR2, object_name IN VARCHAR2, policy_name IN VARCHAR2);
Table 67-3 DISABLE_POLICY Procedure Parameters
| Parameter | Description |
|---|---|
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Schema of the object to be audited. If |
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Name of the object to be audited |
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Unique name of the policy |
The default value for object_schema is NULL. (If NULL, the current log-on user schema is assumed.)
This procedure drops an audit policy.
DBMS_FGA.DROP_POLICY(
object_schema IN VARCHAR2,
object_name IN VARCHAR2,
policy_name IN VARCHAR2);
The DBMS_FGA procedures cause current DML transactions, if any, to commit before the operation unless they are inside a DDL event trigger. With DDL transactions, the DBMS_FGA procedures are part of the DDL transaction. The default value for object_schema is NULL. (If NULL, the current log-on user schema is assumed.)
Note:
Oracle Database automatically drops the audit policy if you remove the object specified in theobject_name parameter of the DBMS_FGA.ADD_POLICY procedure, or if you drop the user who created the audit policy.