Wednesday, April 19, 2023

Google Bard on file system immutability flags in OpenBSD

 Unlike ChatGPT, Bard pretty much nailed it on the initial prompt. (However, Bard refused to answer my questions about the Mars Effect like the ones I gave to ChatGPT, even when reworded to be clear I was asking for descriptions of what the effect is and what explanations are offered rather than asking it to identify causes itself.)

It does lose points for grammar in the second sentence, though!

write a few paragraphs explaining immutable flags in OpenBSD including the commands for setting them and the difference between system and user immutable flags

Sure. Here is a few paragraphs explaining immutable flags in OpenBSD, including the commands for setting them and the difference between system and user immutable flags.

Immutable Flags

Immutable flags are a security feature in OpenBSD that prevent files from being modified, moved, or deleted. They can be set on any file by the superuser, or on files owned by the current user with the chflags command.

To set the immutable flag on a file, use the following command:

chflags schg filename

To unset the immutable flag, use the following command:

chflags nouchg filename

System and User Immutable Flags

There are two types of immutable flags: system immutable and user immutable. System immutable flags are set by the superuser and can only be cleared by the superuser at security level 0 or -1. User immutable flags are set by the owner of the file and can be cleared by the owner of the file at any time.

Commands for Setting Immutable Flags

The following commands can be used to set immutable flags:

  • chflags schg filename: Sets the system immutable flag on filename.
  • chflags uappnd filename: Sets the user append-only flag on filename.

Difference Between System and User Immutable Flags

The main difference between system and user immutable flags is that system immutable flags can only be cleared by the superuser at security level 0 or -1, while user immutable flags can be cleared by the owner of the file at any time.

Example

The following example shows how to set the immutable flag on a file and then clear it:

# Set the immutable flag on the file /etc/passwd
chflags schg /etc/passwd

# Clear the immutable flag on the file /etc/passwd
chflags nouchg /etc/passwd

Benefits of Using Immutable Flags

Immutable flags can be used to improve the security of your system by preventing unauthorized changes to critical files. For example, you could use immutable flags to protect system configuration files, such as /etc/passwd and /etc/shadow, from being modified by attackers.

Disadvantages of Using Immutable Flags

There are a few disadvantages to using immutable flags. First, they can make it difficult to troubleshoot problems with your system. If a file that is set to immutable is corrupted, you will not be able to modify it to fix the problem. Second, immutable flags can slow down your system performance, especially if a large number of files are set to immutable.

Conclusion

Immutable flags are a powerful security feature that can be used to protect your system from unauthorized changes. However, it is important to weigh the benefits and disadvantages of using immutable flags before deciding whether or not to use them on your system.