There are several subtle bugs in various places in fwupd caused by not treating
user-provided offsets into buffers as unsafe. As fwupd runs as root we have to
assume that all user firmware is evil, and also that devices cannot be trusted.
Make a helper to put all the logic into one place and convert all users.
When we install the MCFG carrier config files with QMI PDC, we were
not explicitly selecting one, and that would end up reporting the
"DF" (default) config is in use. Instead, we should explicitly select
the carrier configuration that we were using before the firmware
upgrade operation.
For example, if the device originally was running with the Vodafone
specific carrier configuration (e.g. T77W968.F1.0.0.3.7.VF.009) and we
trigger the upgrade to the next available firmware associated to
the Vodafone carrier (e.g. T77W968.F1.0.0.3.8.VF.009), we would want
the device to boot with the Vodafone carrier config selected, instead
of booting without any config selected (T77W968.F1.0.0.3.8.DF.009).
This also fixes several upgrade problems detected by fwupd, because it
may end up complaining that the target firmware that was selected to
be installed (e.g. VF variant) is not the one actually reported by the
device after the upgrade (e.g. DF variant).
The selection of which is the config to activate is based on mapping
the mcfg file name with the firmware version reported by the module
before the upgrade. E.g. if the VF variant is reported by the module
(T77W968.F1.0.0.3.7.VF.009), fwupd will look for a MCFG file named
with the "mcfg.VF." prefix.
If a device reports that qmi-pdc is supported (e.g. DW5821e that
supports both fastboot and qmi-pdc), we'll end up first running the
fastboot installation before doing the qmi-pdc installation procedure.
These changes also make sure that the MM device inhibition is kept for
as long as the whole process is ongoing. Only after the last method is
run, the inhibition will be removed.
In order to handle devices being exposed in the system while the MM
inhibition is in place, e.g. to be able to run qmi-pdc after fastboot,
a simple udev based watcher is included, which will take care of
creating the FuMmDevice that is not associated to any modem currently
exposed by MM, but that shares all the details of the original device.
This new logic assumes that the devices don't change their USB layout
during a firmware upgrade, which is not a very good assumption, but it
works for the case at hand. If this is not the case, we may need to
end up doing some custom AT port probing instead of relying on the
original one reported by MM being still valid (note that we don't rely
on the device name, as that may change if some other device is plugged
in the system while we're doing the update, we rely on the USB
interface number).
