pure-ftpd: one readonly/non-deletable file in home directory

Question

Is there a way to have a file in the user's FTP home directory without the ability to modify/remove it from that directory over FTP?

So the user has write permissions on his own home folder, thus the ability to remove files. An exception should be made for a single file, which has the same filename and contents for each account.

The solution I'm thinking of right now to run a periodic script to check the presence of that file, and if not, put it back. But I wonder whether there's a better solution than this.

Answer 1

What filesystem do you have? You can try setting immutable attribute on that file

chattr +i filename

Answer 2

As stated, a file can be removed if you have write permission on the directory where it resides. However, you cannot remove a directory if it isn't empty, even if you have write permission on the parent directory. Thus, this hack should work:

mkdir protected
touch protected/test
sudo chown -R root:root protected
sudo chmod -R 755 protected

Now if you try to remove file:

$ rm protected/test 
rm: remove write-protected regular empty file `protected/test'? y
rm: cannot remove `protected/test': Permission denied

And if you try to remove the directory:

$ rm -R protected
rm: descend into write-protected directory `protected'? y
rm: remove write-protected regular empty file `protected/test'? y
rm: cannot remove `protected/test': Permission denied

Answer 3

Set the owner and group of the file to root and make it world readable:

chown root:root filename
chmod 664 filename