I have a linux station (ubuntu 20.04) and I have a mountpoint /share (that is currently mounted as CIFS but I could also use NFS if needed).
I’d like that two different users with local accounts, logged at the same time, to be able to access the mount /share with their own credentials. How can I do that?
1 Answer
That's already how NFS works. It's how NFS has worked since day one.
By default, NFS simply reports the current UID to the server (-o sec=sys), and the server just blindly trusts the client to not lie. If you want more security than that, you will need to set up Kerberos with sec=krb5i.
A similar multi-user mode is available for SMB (cifs) as well – you can enable it by mounting the share with the -o multiuser mount option.
Because SMB authentication isn't UID-based, each user will need to load their own credentials using cifscreds add before they're allowed to access the mount. You can set up pam_cifscreds to make this more automatic (storing the users' login passwords) or, again, run Kerberos.
(Nearly the same Kerberos setup can be used for both NFS and SMB.)
