lsyncd: restrict users to modify file

Question

So, I have a following setup:

• srvRemote:

  • vsftpd server
  • ftp users are write only

• host:

  • has a local directory mounted to srvRemote using sshfs (dirMounted)
  • has a local log directory (dirLocal) lsyncd service running and mirroring data from dirLocal to dirMounted

Thus, if new file is created on dirLocal, new file transfers to srvRemote too. But, if user modifies local files (rewrites them) those changes also affect srvRemote.

Is it any way to restrict such actions? Maybe, it's possible to have a some kind of ledger file which stores diffs somehow?

BTW, I am pretty sure I can set up lsyncd to send data to remote server. I'll try to figure it out later on.