Copying and moving files between qubes is less restrictive
Qubes 4.2.2 includes a fix for #8332: File-copy qrexec service is overly restrictive . As explained in the issue comments, we introduced a change in Qubes 4.2.0 that caused inter-qube file-copy/move actions to reject filenames containing, e.g., non-Latin characters and certain symbols. The rationale for this change was to mitigate the security risks associated with unusual unicode characters and invalid encoding in filenames, which some software might handle in an unsafe manner and which might cause confusion for users. Such a change represents a trade-off between security and usability.
After the change went live, we received several user reports indicating more severe usability problems than we had anticipated. Moreover, these problems were prompting users to resort to dangerous workarounds (such as packing files into an archive format prior to copying) that carry far more risk than the original risk posed by the unrestricted filenames. In addition, we realized that this was a backward-incompatible change that should not have been introduced in a minor release in the first place.
Therefore, we have decided, for the time being, to restore the original (pre-4.2) behavior by introducing a new allow-all-names argument for the qubes.Filecopy service. By default, qvm-copy and similar tools will use this less restrictive service (qubes.Filecopy +allow-all-names) whenever they detect any files that would be have been blocked by the more restrictive service (qubes.Filecopy +). If no such files are detected, they will use the more restrictive service.
Users who wish to opt for the more restrictive 4.2.0 and 4.2.1 behavior can do so by modifying their RPC policy rules. To switch a single rule to the more restrictive behavior, change * in the argument column to + (i.e., change “any argument” to “only empty”). To use the more restrictive behavior globally, add the following “deny” rule before all other relevant rules:
qubes.Filecopy +allow-all-names @anyvm @anyvm deny
For more information, see RPC policies and Qube configuration interface.