Polkit rules for udisks, and udisks2. Compatible with udiskie and Dolphin.

50-udisks.rules

// Original rules: https://github.com/coldfix/udiskie/wiki/Permissions
// Changes: Added org.freedesktop.udisks2.filesystem-mount-system, as this is used by Dolphin.

polkit.addRule(function(action, subject) {
  var YES = polkit.Result.YES;
  // NOTE: there must be a comma at the end of each line except for the last:
  var permission = {
    // required for udisks1:
    "org.freedesktop.udisks.filesystem-mount": YES,
    "org.freedesktop.udisks.luks-unlock": YES,
    "org.freedesktop.udisks.drive-eject": YES,
    "org.freedesktop.udisks.drive-detach": YES,
    // required for udisks2:
    "org.freedesktop.udisks2.filesystem-mount": YES,
    "org.freedesktop.udisks2.encrypted-unlock": YES,
    "org.freedesktop.udisks2.eject-media": YES,
    "org.freedesktop.udisks2.power-off-drive": YES,
    // Dolphin specific
    "org.freedesktop.udisks2.filesystem-mount-system": YES,
    // required for udisks2 if using udiskie from another seat (e.g. systemd):
    "org.freedesktop.udisks2.filesystem-mount-other-seat": YES,
    "org.freedesktop.udisks2.filesystem-unmount-others": YES,
    "org.freedesktop.udisks2.encrypted-unlock-other-seat": YES,
    "org.freedesktop.udisks2.eject-media-other-seat": YES,
    "org.freedesktop.udisks2.power-off-drive-other-seat": YES
  };
  if (subject.isInGroup("storage")) {
    return permission[action.id];
  }
});

You can simplify this by using a "catch all" on org.freedesktop.udisks2. permissions like this:

polkit.addRule(function(action, subject) {
    if (subject.isInGroup("wheel")) {
        if (action.id.startsWith("org.freedesktop.udisks2.")) {
            return polkit.Result.YES;
        }
    }
});

Make note that the policy requires the user to be in storage group. If such group does not exist, create it:

sudo groupadd storage

add yourself to the group (or manually edit /etc/group):

sudo usermod -aG storage yourusername

restart.