This question might sound specific but that is because I'm making my own ssh server (a company needs some specific thing) and it has SFTP but because the server is running as root, it's giving any user that uses the SFTP service access to everything.
For the bash sessions, it's not a problem because I'm running them like so
sudo -H -u $USER bash
but the SFTP I'm using doesn't have user authentication.
I was wondering how do SSH deals with this because I imagine that the default ssh server is also running as root but maybe the SFTP service that SSH uses allows for authentication.
I was thinking that every time a user logs in I can spawn another of my server but only for SFTP like this
sudo -u $USER bash -c "my_server -sftponly
and then the SFTP server will only have access to that users files but I think it's overkill.