This level requires you to read the token file, but the code restricts the files that can be read. Find a way to bypass it :)
To do this level, log in as the level04 account with the password level04. Files for this level can be found in /home/flag04.
We can bypass this check by creating a symbolic link.
ln -s /home/flag04/token /home/level04/foo
And you’ll see the token in the output.