Скачать или смотреть Granting Exclusive Permissions to Functions in PostgreSQL

Discover how to give a function in PostgreSQL exclusive rights to modify a table using user permissions and security definer roles.
---
This video is based on the question https://stackoverflow.com/q/64533408/ asked by the user 'Gela' ( https://stackoverflow.com/u/10690755/ ) and on the answer https://stackoverflow.com/a/64534301/ provided by the user 'Laurenz Albe' ( https://stackoverflow.com/u/6464308/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: PostgreSQL. exclusive permission to a function to modify a table

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Granting Exclusive Permissions to Functions in PostgreSQL

In the realm of database management systems, permissions play a crucial role in controlling access to data. One common question that arises among PostgreSQL users is: Is it possible to grant a function exclusive rights to modify a table? This is especially relevant for situations where you want to limit modifications to a specific function while preventing other accesses or modifications to that table.

Understanding the Problem

By default, PostgreSQL allows various roles (or users) to interact with tables, which means that any user with the necessary privileges can modify data in the tables. The challenge is to restrict the modification permissions to a single function and prevent other users or functions from accessing and altering the table.

The Need for Exclusive Permissions

Here's why you may want to provide exclusive permissions:

Security: By limiting who can modify data, you reduce the risk of unintended changes.

Data Integrity: Ensures that only predefined logic (contained in your function) can alter the data, maintaining consistency.

Accountability: Tracking changes and understanding who made them becomes simpler when access is restricted.

The Solution

To implement exclusive rights for a function in PostgreSQL, you'll have to use a combination of roles and permissions. Here's a detailed breakdown of how to accomplish this:

Step 1: Create a NoLogin Role

First, you can create a special role that won’t log in but will own the function that can modify the table. This role will not have any direct access to the database.

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Create the Function

Next, create the function that will perform the modifications on the table. Make sure to declare it as a SECURITY DEFINER. This ensures that the function runs with the permissions of its owner instead of the user invoking it.

[[See Video to Reveal this Text or Code Snippet]]

Step 3: Grant Table Modification Permissions

Now, grant the no_login role permission to modify the target table. This is a critical step, as it restricts table access to just this role.

[[See Video to Reveal this Text or Code Snippet]]

Step 4: Set Ownership

Finally, make sure that the no_login role owns the function you created earlier. This ensures that when the function is executed, it will inherit the permissions granted to no_login.

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By following the steps outlined above, you've successfully restricted the ability to modify a table to a specific function in PostgreSQL. This approach not only enhances security but also ensures that data can only be altered through controlled processes, preserving data integrity. By implementing a NOLOGIN role in conjunction with a SECURITY DEFINER function, you can achieve the exclusive permissions that are required.

Feel free to reach out or leave a comment if you have further questions or need clarifications on PostgreSQL permissions!