There's a kernel-imposed boundary between being a user and being root. Right now there's also a partial barrier between being root and being the kernel that's fairly easily circumvented. Now that we can protect the on-disk copy of the kernel from root, there's also interest in protecting the in-memory copy of the kernel from root.

Yes. And lockdown helps with (right?):

a) locking root out of kernel

b) locking users from becoming root

I interpret the reasoning as: if we can't do a AND b we won't bother with b. Which is confusing because b is many orders of magnitudes more important than a.

b) is a barrier that's already supposed to exist, so these patches don't have an impact on it.

Supposedly yes, but shoudln't it vastly reduce the attack surface by not having to worry (compared to now) about all device drivers that use DMA (which otherwise is just impossible to keep track of).

In my opinion reducing that attack surface alone on b) has a much higher impact than a) could ever achieve.

The stuff lockdown impacts is stuff that only root can do right now, so in theory it's only handling channels that are irrelevant to b). Users should already be prevented from triggering arbitrary DMA, for instance.

Well, should, again, device drivers are notoriously bad and some protection against that is extremely valuable.

a) prevents a temporary breach of b) from turning into a persistent attack. b) is still very important, so important that when b) breaks it is considered a CVE!

So... you know, it occurs to me that none of this would be a problem if people understood two things:

A) Computers are tools designed to do whatever the user tells them to do.

B) The original architecture of the Internet assumed a network connecting implicitly trusted users

Stop trying to mess up a perfectly good tool by making it nigh impossible to work with, and redesign a networking/computing infrastructure that doesn't implicitly trust all users as a fundamental assumption.

This type of thing is getting completely out of hand.

If you want security SO badly you are willing to sacrifice billions of potential users freedoms to use their hardware as they see fit, coming up with a second "SECTERNET" architecture should be a price you're willing to pay right?

This pattern of trying to lock a user out of any tier of control of their own machine reeks of the continuing attempts by companies to deprive users of the privilege of ownership.

I realize it may be difficult to see for some, but this is a literal case of the road to Hell being paved with good intentions.

People don't need to be "protected" by building their volition out of the system.

"root user" is a term that we choose to mean what we want it to. Some people in the Linux community want to restrict the root user / cap_sys_admin so that even them cannot tamper with a secure kernel or run ring0 code under certain configurations. I think this is a great idea.