> This configuration work OK for loggin with an SFTP client.
> The user home is changed to the /datos/chroot/cssa and its
> chrooted to / . This is not OK. The correct chroot directory
> for the user is /datos/chroot/ .
> Of course, I can change to the root directory /, and this is
> the problem. I want to limit the user to the directories over
> /datos/chroot.
> Where is the problem or error?
> How I make the chroot directory to /datos/chroot/?

OpenSSH does not support chrooted sftp out-of-the-box, last I checked.
There are a few patches out there that add support for it.

One is here: http://chrootssh.sourceforge.net/