[Unison-hackers] Multi-user, single UID ideas for Unison

[nikp123]

Hi,
I've recently joined here as I've become aware of this particular 
mailing list.
I was considering whether it is in scope of the Unison project to add 
anything relating to isolating folders for a SSH-ran server process for 
the purposes of protecting other users and preventing any potential data 
leaks.

I went into more detail in this GitHub issue (that's why I got 
redirected here): https://urldefense.com/v3/__https://github.com/bcpierce00/unison/issues/978__;!!IBzWLUs!XBSSGv7w5Z-JF7pewm5J_Lz-cysVciDZ6r1nyY3JRsLm0I76R90jwUhdlctK4mP5zZ7354Q-xZqg4YoUFEMWAcWxfkGBSQ$ 

So my use case relies on software that isn't able to authenticate and 
change file/directory UIDs depending on what user is authenticated such 
as FileBrowser (https://urldefense.com/v3/__https://github.com/filebrowser/filebrowser__;!!IBzWLUs!XBSSGv7w5Z-JF7pewm5J_Lz-cysVciDZ6r1nyY3JRsLm0I76R90jwUhdlctK4mP5zZ7354Q-xZqg4YoUFEMWAcXtmdxfyg$ ). For that 
reason I couldn't make Unison work with it without significant 
compromises (using bindfs, which has it's own issues) or risk potential 
data leaks (such as with Unicloud: https://urldefense.com/v3/__https://github.com/agarbato/unicloud__;!!IBzWLUs!XBSSGv7w5Z-JF7pewm5J_Lz-cysVciDZ6r1nyY3JRsLm0I76R90jwUhdlctK4mP5zZ7354Q-xZqg4YoUFEMWAcUTOb6bUQ$ ).

My solution (that I have proposed) would require Unison to prevent the 
user from reading outside of its launch directory, effectively 
preventing the user from being able to leak data from other users or the 
server itself.

Since the GitHub maintainer told me to specify if I have anyone behind 
me: No, I do not. This is just me. I am a student ATM and this is more 
of a personal request than anything. I am enjoying the fruits of the 
labor done here already and this is just a nicety that could be added on 
top of it (allows for more use-cases).

But I am not asking for any *particular* solution, I'm asking if the 
solution proposed here sounds sane or even practical. Yes, I do 
understand it's niche for almost all of you, but I'd like for Unison's 
syncing prowess to be useful outside of the server 
administrator/poweruser sphere. This was just one way of achieving that 
(albeit impractical for most people).

Any suggestions/comments or ideas are welcome, I'd just like to know 
what you all think about this before any action is made. And if it is 
considered to be in the scope of Unison, how will we go about 
implementing this. Maybe there even **is** a solution that doesn't 
require modifications to Unison itself and I'm just not aware of it? Who 
knows, that's why I'm posting here ;)

Thanks for your attention,
nikp123.