Oracle definer rights and invoker rights are two security concepts used to control access to the privileges required during runtime of a user-created procedure or a program unit. In a definer’s rights, the procedure executes with the privileges of the creator or owner of it. The privileges are associated with schema in which that procedure was created. While in invoker’s rights procedure runs with the privileges of the current user or the user who is executing it.

Table of Content

Introduction

In the of Oracle PL/ programming, there are two types of execution rights that can be granted to users: Definer Rights and Invoker’s Rights. the differences between these two types of rights is for ensuring the security and integrity of your database.

What are Definer Rights in Oracle?

Definer Rights, also known as Owner Rights, allow a user to execute a PL/SQL program with the privileges of the owner of the program. This means that the program will run with the privileges of the user who created the program, regardless of who is executing it.

Syntax

When to Use:

• If you want the procedure to always execute with the same permissions (i.e., the permissions of the user who defined the procedure).
• Suitable when the procedure needs to access schema objects owned by the definer, and the invoker does not have direct privileges on those objects.
• Example use case: A central schema where common procedures and data access are stored, and other users simply call those procedures without needing direct access to the underlying data.

Example:

CREATE OR REPLACE PROCEDURE definer_proc AS 
BEGIN
  -- This procedure will run with the privileges of the user who created it
  INSERT INTO employees VALUES (1, 'John Doe', 'Marketing');
END;

In this case, if User A calls this procedure, it will run with the privileges of User B (the definer). This is useful if User A doesn’t have permissions to insert into the employees table directly.

Advantages of Definer Rights

• Simplified security management
• Improved performance due to reduced checks
• Easier debugging and troubleshooting

Disadvantages of Definer Rights

• Lack of granular control over user permissions
• Increased risk of privilege escalation

What are Invoker’s Rights in Oracle?

Invoker’s Rights, also known as Caller Rights, allow a user to execute a PL/SQL program with their own set of privileges. This means that the program will run with the privileges of the user who is executing it, rather than the owner of the program.

Syntax

When to Use:

• If you want the procedure to respect the privileges of the user calling the procedure.
• Suitable when the procedure needs to be executed with varying privileges depending on who calls it.
• Example use case: In multi-tenant systems, where different users might have access to different schemas, and the same procedure is expected to behave differently depending on who invokes it.

Example:

CREATE OR REPLACE PROCEDURE invoker_proc AUTHID CURRENT_USER AS 
BEGIN
  -- This procedure will run with the privileges of the user who invokes it
  INSERT INTO employees VALUES (2, 'Jane Doe', 'Finance');
END;

Here, if User A calls the procedure, the procedure will execute with User A‘s privileges. If User B calls the same procedure, it will run with User B‘s privileges.

Advantages of Invoker’s Rights

• Enhanced security by limiting access to specific resources
• Fine-grained control over user permissions
• Reduced risk of privilege escalation

Disadvantages of Invoker’s Rights

• Potential performance overhead due to increased checks
• More complex security management

Oracle Definer Rights & Invoker’s Rights: Restrictions

For types, the following limitations are applicable:

• This clause does not apply to VARRAY types or nested tables; it is only acceptable for ADTs.
• If you are defining a subtype, you can clarify things by specifying this clause. You are unable to specify a different value than the one that was set for the supertype, though, because a subtype inherits the AUTHID attribute of its supertype.
• You have to build the subtype in the same schema as the supertype if the supertype was generated using AUTHID DEFINER.

Oracle Definer Rights & Invoker’s Rights: Points to Remember

• It describes the AUTHID property of the functions, procedures, and explicit cursors stated in the package specification when it appears in the package declaration.
• It indicates the function’s AUTHID attribute when it shows up in a standalone function declaration.
• A subprogram declaration can contain only one instance of the invoker_rights_clause.
• It specifies the procedure’s AUTHID attribute when it shows up in a standalone procedure declaration.
• It describes the AUTHID property of the member functions and procedures of an ADT when it exists in the ADT.

Oracle Definer Rights & Invoker’s Rights: Key Differences

1. Ownership: Definer Rights run with the privileges of the program owner, while Invoker’s Rights run with the privileges of the user executing the program.
2. Security: Definer Rights can lead to privilege escalation, while Invoker’s Rights offer more granular control over user permissions.
3. Performance: Definer Rights may offer better performance due to reduced checks, while Invoker’s Rights can introduce overhead.

Oracle Definer Rights & Invoker’s Rights: Best Practices for Choosing

• Consider the level of security required for the PL/SQL program.
• Evaluate the potential impact on performance.
• Determine the need for granular control over user permissions.

Conclusion

In conclusion, understanding the differences between Oracle Definer Rights and Invoker’s Rights is essential for ensuring the security and performance of your PL/SQL programs. By carefully evaluating the advantages and disadvantages of each type of rights, you can make informed decisions that align with your specific requirements.

How To Choose?

• Choose Definer Rights if you need to centralize control over permissions and access specific objects without exposing them to calling users.
• Choose Invoker Rights if you need flexibility and want the procedure to work within the scope of the calling user’s permissions, especially in multi-tenant or dynamic environments.

FAQs

Q1. What are the main differences between Definer Rights and Invoker’s Rights?

Definer Rights run with the privileges of the program owner, while Invoker’s Rights run with the privileges of the user executing the program.

Q2. Why is it important to consider security when choosing between Definer Rights and Invoker’s Rights?

Security is crucial to prevent unauthorized access and potential privilege escalation in Oracle PL/SQL programs.

Q3. How can I determine whether to use Definer Rights or Invoker’s Rights for my PL/SQL program?

Consider the level of security required, the impact on performance, and the need for granular control over user permissions. Use definer rights when you want to grant users access to data they don’t have direct privileges for, but through a controlled procedure. Use invoker rights when you want the procedure to adapt to the calling user’s privileges, or when you need to prevent privilege escalation

Q4. Are there any potential drawbacks to using Definer Rights over Invoker’s Rights?

Definer Rights can lead to privilege escalation and lack of control over user permissions.

Q5. What are some best practices for managing user privileges in Oracle PL/SQL programs?

Evaluate security requirements, consider performance implications, and assess the need for granular permissions when choosing between Definer Rights and Invoker’s Rights.

Q6. Are there any performance differences between definer and invoker rights procedures?

Generally, definer rights procedures might have a slight performance advantage because Oracle can pre-determine all privileges at compile time. Invoker rights procedures require privilege checking at runtime. However, the difference is usually negligible in most scenarios, and security considerations should typically outweigh minor performance variances.

Q7. How do definer and invoker rights affect dynamic SQL in procedures?

In definer rights procedures, dynamic SQL executes with the definer’s privileges, potentially accessing objects the invoking user can’t directly access. In invoker rights procedures, dynamic SQL runs with the caller’s privileges, which can limit or expand access based on the user’s rights.

Q8. Can I change a procedure from definer rights to invoker rights (or vice versa) after it’s created?

Yes, you can alter an existing procedure to change its AUTHID setting. Use the ALTER PROCEDURE (or FUNCTION or PACKAGE) command with the AUTHID clause. However, be cautious as this can significantly change how the procedure behaves and interacts with data.

Q9. Is definer right’s and Invokers rights are present only in Oracle?

No. this concepts are also available in other database programming languages such as in PostgreSQL it is termed as SECURITY DEFINER and SECURITY INVOKER.

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