SFTP chroot: Writable root

[Colin Watson]

On Sat, Jan 06, 2018 at 02:43:51AM +1030, David Newall wrote:
> I note that Ubuntu 16 (I assume some others, too) refuses to hard link a
> file to which the user cannot write.  I don't remember if that is
> traditional behaviour; I think not; it's probably SELinux.

Ubuntu doesn't use SELinux (at least not by default or without
significant work), but rather AppArmor.  However, the hard-link
protection is neither of those, but is rather a "protected_hardlinks"
feature in the VFS introduced in Linux 3.6.

-- 
Colin Watson                                       [cjwatson at debian.org]