The permission store uses documents st_dev to store permissions but st_dev may be virtual and may not be persistent

[lbaudin]

Operating System

Ubuntu, Fedora

XDG Desktop Portal version

1.18

XDG Desktop Portal version (Other)

No response

Desktop Environment

GNOME

Desktop Environment (Other)

No response

Expected Behavior

The permission store should keep permissions of opened (persistent) document. For instance, a recently opened file should be available after several reboots if it has not been deleted (and, of course, if the app asked the permission to be persistent).

Current Behavior

The permission store, according to this page, uses the device id st_dev to store permissions. However, with btrfs (or, I was told, ext4+lvm), the device id is virtual and may not persist with reboots (especially, for instance, in fedora silverblue when an upgrade is carried out).

As a result, permissions are not really persistent and, for instance with Secrets [1], new permissions may be necessary:

Table      Object     App                     Permissions                  Data
background background org.gnome.World.Secrets yes                          0x00
documents  74ae3507   org.gnome.World.Secrets read,write,grant-permissions (b'/home/lucas/test.kdbx', 39, 256, 0)
documents  33679dc0   org.gnome.World.Secrets read,write,grant-permissions (b'/home/lucas/test.kdbx', 61, 256, 0)
documents  76a9a32b   org.gnome.World.Secrets read,write,grant-permissions (b'/home/lucas/test.kdbx', 64, 256, 0)

(see here for more examples)

And something looks definitively wrong in the exposed filesystem:

[📦 org.gnome.World.Secrets ~]$ ls /var/run/user/1000/doc/*

/var/run/user/1000/doc/33679dc0:
'test.kdbx'

/var/run/user/1000/doc/74ae3507:
'test.kdbx'

/var/run/user/1000/doc/76a9a32b:
'test.kdbx'

/var/run/user/1000/doc/c4a70ceb:
[📦 org.gnome.World.Secrets ~]$ ls /var/run/user/1000/doc/*/*
ls: impossible d'accéder à '/var/run/user/1000/doc/33679dc0/test.kdbx': Aucun fichier ou dossier de ce type # Meaning no such file or directory
ls: impossible d'accéder à '/var/run/user/1000/doc/76a9a32b/test.kdbx': Aucun fichier ou dossier de ce type
'/var/run/user/1000/doc/74ae3507/test.kdbx'
[📦 org.gnome.World.Secrets ~]$ 

[1] Issue here. In this case it breaks the "recent files" menu.

Steps to Reproduce

1. Select a file with a flatpak app from, for instance, a btrfs subvolume
2. "Wait some time" (i.e. wait for something that may change the device id, I think it happens with a silverblue upgrade+reboot, but it also happens several times a week in a regular Ubuntu install)
3. The flatpak app does not have access to the file anymore

Anything else we should know?

If my diagnosis is correct, this is probably not trivial to fix. It also happens with network shares mounted via gvfs. Maybe the mount point should be recalled in the permission store?