EDIT
TO EVERYONE ASKING TO OPEN AN ISSUE ON GITHUB, IT HAS BEEN OPEN SINCE JULY 6: https://github.com/LemmyNet/lemmy/issues/3504
June 24 - https://github.com/LemmyNet/lemmy/issues/3236
TO EVERYONE SAYING THAT THIS IS NOT A CONCERN: Everybody has different laws in their countries (in other words, not everyone is American), and whether or not an admin is liable for such content residing in their servers without their knowledge, don't you think it's still an issue anyway? Are you not bothered by the fact that somebody could be sharing illegal images from your server without you ever knowing? Is that okay with you? OR are you only saying this because you're NOT an admin? Different admins have already responded in the comments and have suggested ways to solve the problem because they are genuinely concerned about this problem as much as I am. Thank you to all the hard working admins. I appreciate and love you all.
ORIGINAL POST
You can upload images to a Lemmy instance without anyone knowing that the image is there if the admins are not regularly checking their pictrs database.
To do this, you create a post on any Lemmy instance, upload an image, and never click the "Create" button. The post is never created but the image is uploaded. Because the post isn't created, nobody knows that the image is uploaded.
You can also go to any post, upload a picture in the comment, copy the URL and never post the comment. You can also upload an image as your avatar or banner and just close the tab. The image will still reside in the server.
You can (possibly) do the same with community icons and banners.
Why does this matter?
Because anyone can upload illegal images without the admin knowing and the admin will be liable for it. With everything that has been going on lately, I wanted to remind all of you about this. Don't think that disabling cache is enough. Bad actors can secretly stash illegal images on your Lemmy instance if you aren't checking!
These bad actors can then share these links around and you would never know! They can report it to the FBI and if you haven't taken it down (because you did not know) for a certain period, say goodbye to your instance and see you in court.
Only your backend admins who have access to the database (or object storage or whatever) can check this, meaning non-backend admins and moderators WILL NOT BE ABLE TO MONITOR THESE, and regular users WILL NOT BE ABLE TO REPORT THESE.
Aren't these images deleted if they aren't used for the post/comment/banner/avatar/icon?
NOPE! The image actually stays uploaded! Lemmy doesn't check if the images are used! Try it out yourself. Just make sure to copy the link by copying the link text or copying it by clicking the image then "copy image link".
How come this hasn't been addressed before?
I don't know. I am fairly certain that this has been brought up before. Nobody paid attention but I'm bringing it up again after all the shit that happened in the past week. I can't even find it on the GitHub issue tracker.
I'm an instance administrator, what the fuck do I do?
Check your pictrs images (good luck) or nuke it. Disable pictrs, restrict sign ups, or watch your database like a hawk. You can also delete your instance.
Good luck.
An option to prevent users to upload unless their DNS has been whitelisted. It would require explicit permission to upload, which could be handy for smaller instances.
Not IP. DNS whitelist. This way if a geography or subnet is responsible for illegal material they are only allowed in if an instance granted +w.
Every person on the internet has a DNS record that loops back to them. The DNS has a topography so that various elements of a domain could be whitelisted, or not.
It would be trivial to queue a request to white list, where an administrator could decide if it is worth it, having it auto expire over time.
Instance admins could share sources of bad actors.
heuristics could help determine the risk of an approval action.
That’s how the internet works? Every device on the internet has an IP address and most IP devices are assigned a unique DNS name for that address.
That DNS has a topography (a.b.c.com) so that you could whitelist (*.b.c.com). Mobile Devices, Home Networks, College & Corporate campuses…all are probably going to have a DNS associated with then. Entire swathes of the internet could be whitelisted fairly easily…or not.
Yes it would not be fool proof. However IP whitelisting would rapidly lose its meaning.
fwiw the wide area / global internet would fall apart without DNS.
Local networking ignores DNS for the most part. Your home router, for example, doesn’t need a DNS to route packets from your ISP to your device. or IP for that matter. Ethernet alone is enough.
DNS itself is unrelated to geography.
Geography at best is an ISP convention.
Most geographic maps utilize physical routing to guess a DNS location. At best a DNS relationship to geography is a finger in the air, many times it’s just wrong.
if someone had no DNS it is more likely they are up to no good when accessing Lemmy. It is not foolproof however a smaller instance would be reasonably protected.
They, I imagine, care less about who the user is (username) and more about the user’s internet gateway (DNS). Only the instances that woke up to GB of child pornography know how they got there.
There is a cpu hit for this sort of thing so it is not free.