We have an NFS export for any of our users to install and maintain useful software for the network mounted at /public on our clients. On the NFS server, this directory is world writable with the sticky bit set(like /tmp).
One of the users of this service has a symbolic link in /public to an executable file. Since we upgraded our workstations from Ubuntu 9.04 to 10.10, we get permission denied when we try to execute this file via the symbolic link. If we remove the sticky bit, we no longer get permission denied.
I haven't found anything in our logs or dmesg. Is this an app armor feature or a bug introduced between Ubuntu 9.04 and 10.10?