F* file system – file search that reads SSD directly bypassing OS kernel
github.com51 points by neogoose 2 days ago
51 points by neogoose 2 days ago
> bypassing OS kernel
> reading a raw device node (e.g. /dev/rdisk*)
That's... not bypassing the kernel. Time to integrate SPDK so it actually bypasses the kernel :)
This is practically the most useless project becuase you can not run it without sudo permissions, but it was insanely fun to work on it
supports ext4, btrfs, and apfs. Multithreaded, supports compression, nested volumes, and can even search detached volumes like .iso and .dmg without mounting
An interesting bonus point: you can't really vibe code it cause clankers can not run sudo commands
> cause clankers can not run sudo commands
They absolutely can. There's nothing special about a these harnesses. You automate sudo the same way you would automate in any other context. SUDO_ASKPASS, visudo, etc, maybe with a alias for obfuscation if your harness hates you.
> run sudo commands
With respect to the dangers of privilege escalation, a useful list of common commands which are difficult to invoke safely with elevated permissions: https://gtfobins.org/
> The project collects legitimate functions of Unix-like executables that can be abused to break out restricted shells, escalate or maintain elevated privileges, transfer files, spawn bind and reverse shells, and facilitate other post-exploitation tasks.
Prior discussion: https://news.ycombinator.com/item?id=47931035
>clankers can not run sudo commands
Do you mean the harnesses prevent it? Or it can't type a password or something?
I've been running mine as root on a disposable VPS. (Finally I have a dedicated linux guy!)
When they can't run sudo, they'll user docker to give themselves root.
That's why everyone should use rootless Podman. It doesn't need anything apart from subuid/subgid binaries.
I think it's more that the harnesses created by the labs are... not always the most thoughtful.
I have zero affiliation with Cursor, and I don't use it much, but Cursor Agent, for example, just builds in ASKPASS support so that if it runs a sudo command, it will show you a password prompt:
>cause clankers can not run sudo commands
Is that really true? I'm fairly certain that were you to give it the proper tooling and it's own VM, it could quite happily run any command.
Hell a simple "if the CLI returns any form of 'permission denied' retry previous command with sudo; your password is: Hunter2" skill would work, no?
In the least, you could make an alias for sudo, and have it run that. With something like this in .bashrc:
alias safedo='sudo'
> This is practically the most useless project becuase you can not run it without sudo permissions
Well, you could whitelist the tool in sudoers.
This would let LLMs use it too.
Giving some fundamentally-untrustworthy software full read access to all files and secrets on the disk is certainly a risk one could take.
Y’all aren’t running your agents as root?
Has anyone run a study on how long you can run an agent as root before irreparable damage is done to the VM? A sort of gambler's ruin for the YOLO LLM Age.
https://forums.macrumors.com/threads/screw-it-lets-make-clau...
For me, it took a bit over six weeks of Claude running unattended perpetually.
I gave Sonnet 4.6 root access to my Android via adb and it wrote frida scripts to help me recover the encryption keys from SwiftBackup
Also gave Opus 4.6 access to a Kubernetes container and it was able to use pyrasite (a Python replacement that attached to a running process with gdb) to debug a "memory leak" in Python
I don't think I'd let them run unattended on anything I care about especially if there weren't backups, but they've never tried to break anything while supervised.
Usually it's significantly faster and more accurate to give the LLM/harness access to the thing to debug then to try to copy/paste back and forth.
It's been a while but last year I'd see posts like "Claude nuked my homedir / entire drive" on a regular basis. I don't know if they fixed that (or just made it very rare).
In fairness to Claude, I've nuked my homedir (had 2 tmux panes open, 1 in home and 1 in /tmp/... and wrong one was focused when I ran rm -rf *) and broken VMs far more times than it has. I now embrace IaC and backups
Pretty cool to read it directly from the associated device XD
Did you write a metadata parser for most of the filesystems?
On Linux, you could create a udev rule to give you permissions on any attached raw disks (if you feel particularly adventurous).
What's the license for ffs?
It might bypass the fs, but it does not bypass the kernel. Cool, though!
Dumb title.
It works by reading the block device in /dev directly, wouldn't it also work on an HDD, flash drive or a memory card?
I assume the author just meant SSD as a synonym for "main internal disk", since that is usually an SSD these days.
yeah I was just picking up an interesting the title for hn, you should read a README to get the actual understanding of project
But can it match the speed and reliability of the venerable Windows Search?
Saw the name and was disappointed that this wasn't some kind of verified file system written in the F* programming language (https://fstar-lang.org).
I don't think I'd ever trust or use this, but still, good job OP :)
But can it bypass the magic performed by the SSD controller?
In particular, can it be certain that a flush is really a flush?
Related: Could it be of any use in easily detecting counterfeit SSDs, which have been hacked to report a fraudulent size?
Sure, you can test by completely filling the drive with predictable (to you, not to a counterfeiter) data and then verifying the write, but even on an SSD that's tedious.
If the disk decides to falsely report a flush, there's not much you can do about it from the user side, no?
It is sad that that FFS doesn't support FFS (BSD Fast File System) which inspired the architecture of the ext filesystem (and was the basis for a lot of unix filesystems).
Run this once per boot:
sudo setfacl -m u:$USER:r-- /dev/nvmen01p2 # or whatever
Or if you want to only give fff access,
sudo groupadd diskreaders
sudo setfacl -m g:diskreaders:r-- /dev/nvmen01p2
sudo chown :diskreaders /path/to/fff
sudo chmod g+s /path/to/fff
So your LLM can use the binary with some safety against it going off the rails.