It isn’t perfect, even if you try your hardest it won’t be perfect and to argue it’s not difficult is absurd.
You don’t know everything, you don’t own the stack. So how are you going to create a secure anything top to bottom - you can’t.
This is absolutely not true. It's a matter of cost. Exploitation can cost on the order of 10K, 100K, 1M, 10M, etc. A straightforward one would be something like "MD5 collisions are on the order of $100K-1M" (a while ago, at least) so if you used MD5 you knew that it costs about that much to bypass the control. Moving to SHA1 pushes you massively out of that space, even if that algorithm has flaws.
I'm sure that Firecracker has vulnerabilities. Cost of exploitation is likely >100K, likely >1M. gVisor is likely on the same order of magnitude and these two technologies stack because they address the same surface and can be used in conjunction.
Software absolutely doesn't have to be perfect, it just has to be costly to attack and it's hilariously easy to drive costs way way way up.
This is incorrect. It's actually the whole point. Imagine you're an attacker in a gvisor container with a Firecracker hypervisor around you, and a proxy on the host holds a signing secret that gets exposed through the VM virtual device.
Getting access to that secret is not one crack. You need to escalate out of gvisor. That likely gets you control over the Sentry process - let's ignore its sandboxing and just say "you're an unprivileged user".
Any viable attack on Firecracker requires either KVM / hardware exploits (>$1M but definitely real) or has to start at the kernel. Okay, that's about 10-50k to get a kernel LPE, maybe 5K in tokens these days.
So you're in the kernel in the guest of the VM. Time to expoit firecracker lol. It's... never been done. There are like two promising CVEs ever and they're not actually exploitable, no one has done it. Okay, so like, hand waving, let's say it's about $1M to exploit firecracker.
Great, you're unprivileged on the guest. We'll just kind of ignore the additional sandboxing that Firecracker does.
NOW you can try to attack the proxy by scraping its memory or whatever.
This is literally millions of dollars for standard infrastructure hardening and you could go so much further. You can trivially make kernel exploitaton 10x harder, you can make gvisor escapes much much harder, you can move the proxy signing into a TPM (depending on requirements but whatever), you can move the proxy to another computer altogether, you could fuzz these systems for days or run agents against them or whatever.
But one thing is certain - it is never "one crack".
We know the AI will get smarter every year, we know it has escaped and will escape again. We can also just assume that someone somewhere will train up some just plain evil AI.
It's no different than the real world. Sure there exists some amazing prisons for people, but that doesn't do anything to help with all the bad people in the world outside of prison.