[RFC] dfu: remove UPDATE_TFTP

[AKASHI Takahiro <takahiro.akashi@linaro.org>]

On Thu, Jul 16, 2020 at 06:44:43AM +0200, Heinrich Schuchardt wrote:
> On 7/16/20 3:52 AM, AKASHI Takahiro wrote:
> > On Wed, Jul 15, 2020 at 04:42:20PM +0200, Heinrich Schuchardt wrote:
> > On 15.07.20 16:06, Michal Simek wrote:
> >>>>
> >>>>
> >>>> On 15. 07. 20 15:23, Lukasz Majewski wrote:
> >>>>> Hi Heinrich,
> >>>>>
> >>>>> On 15.07.20 13:24, Lukasz Majewski wrote:
> >>>>>>>> Hi Heinrich,
> >>>>>>>>
> >>>>>>>>> Using UPDATE_TFTP the firmware can be updated from tFTP
> >>>>>>>>> by writing to NOR flash. The same is possible by defining
> >>>>>>>>> a dfu command in CONFIG_PREBOOT.
> >>>>>>>>>
> >>>>>>>>> The dfu command cannot only write to NOR but also to
> >>>>>>>>> other devices. In README.dfutfp UPDATE_TFTP has been
> >>>>>>>>> marked as deprecated.
> >>>>>>>>
> >>>>>>>> Could you also write in the proper README the steps
> >>>>>>>> necessary to have the same functionality as with
> >>>>>>>> UPDATE_TFTP with dfu and preboot? I think that it would be
> >>>>>>>> good to have it written down in ./doc.
> >>>>>>>>
> >>>>>
> >>>>> doc/README.dfutftp already describes the necessary steps as:
> >>>>>
> >>>>> * enable CONFIG_DFU_TFTP * enable CONFIG_PREBOOT * put a string
> >>>>> like "dfu tftp 0 mmc 0" into the "preboot" env variable
> >>>>>
> >>>>> Do you want me to explicitly write that "dfu tftp 0 mtd 0"
> >>>>> replaces the former auto-update functionality?
> >>>>
> >>>> I am curious if that command is really dfu tftp 0 mtd 0.
> >
> > Lukasz was asking about the replacement of the update that was
> > executed when running with CONFIG_UPDATE_TFTP=y. This function that I
> > am removing could only write to NOR flash. The update defined via
> > CONFIG_PREBOOT is much more flexible and can server other storage media.
> >
> >> One of my concerns regarding CONFIG_PREBOOT is that it depends
> >> on the "preboot" variable.
> >> What this means is that, if a user unsets this variable (accidentally
> >> or not), 'automatic firmware update' won't be executed.
> >> This can be a critical issue if the system administrator intends to
> >> *enforce* the update.
> >> (I know there are more issues regarding enforcement though.)
> 
> You could also defeat the old tFTP auto-update by setting "serverip" to
> a reserved value like 240.0.0.0. So there is no new vulnerability
> introduced here.

?
I'm not talking about tftp here, but about a potential issue
in the current framework.

-Takahiro Akashi


> Anyway no board uses the old tFTP auto-update while DFU is enabled in
> 273 config files and DFU_TFTP in 2.
> 
> Best regards
> 
> Heinrich
> 
> >
> >> That is why I added UEFI capsule update hook in main_loop() as
> >> a compile-time option.
> >
> >> Thanks,
> >> -Takahiro Akashi
> >
> >
> > The different accessible devices are described in doc/README.dfu.
> > "ram" is one of them.
> >
> > Best regards
> >
> > Heinrich
> >
> >>>>
> >>>> I have just tested it on zynqmp with copying images to ram and
> >>>> command is just dfu tftp ram 0. It means I think it would be worth
> >>>> to list options which are really used by different back ends
> >>>> because it is not fully clear from help how to exactly define it.
> >>>>
> >>>> dfu tftp [<interface> <dev>] [<addr>] - device firmware upgrade via
> >>>> TFTP on device <dev>, attached to interface <interface> [<addr>] -
> >>>> address where FIT image has been stored
> >>>>
> >>>> Thanks, Michal
> >>>>
> >