I have a CentOS host machine with a Windows 7 virtual machine in VMware. There is a shared drive on the host machine (NFS share with other machines on the network) which has been configured with ACLs so that all files created there are editable by the group. This drive is also mounted within the VM as a Shared Folder using the VMware sharing functionality.
Through lots of trial and error, I have determined that editing a file from the VM will "reset" the permissions of the file to be owner-editable only, even if it had been manually changed before. What is happening is that Microsoft Office creates a temporary file as it is editing, and when the document is saved, the original is deleted and the temporary file is renamed. The "new" file now has default permissions set to be read only for the group, and the file is now owned by the current editor.
I read somewhere that the default permissions from the VM are a setting in the Samba server. However, we went in and changed that to no effect. In fact, it didn't look like there was even a Samba server even running while the VM was open.
I'm at a loss of where to go next. It is a pain to have to run a chmod every time someone finishes editing a file so that we don't have to spin off version #23 of the file just to be able to save it.