Re: [tegrarcm PATCH v1 3/4] Add option --signed

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 03/09/2016 02:01 PM, Jimmy Zhang wrote:
>
>
>> -----Original Message-----
>> From: Stephen Warren [mailto:swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org]
>> Sent: Wednesday, March 09, 2016 9:29 AM
>> To: Jimmy Zhang
>> Cc: Allen Martin; Stephen Warren; alban.bedel-RM9K5IK7kjKj5M59NBduVrNAH6kLmebB@public.gmane.org; linux-
>> tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>> Subject: Re: [tegrarcm PATCH v1 3/4] Add option --signed
>>
>> On 03/08/2016 05:36 PM, Jimmy Zhang wrote:
>>>
>>>
>>>> -----Original Message-----
>>>> From: Stephen Warren [mailto:swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org]
>>>> Sent: Monday, March 07, 2016 12:32 PM
>>>> To: Jimmy Zhang
>>>> Cc: Allen Martin; Stephen Warren; alban.bedel-RM9K5IK7kjKj5M59NBduVrNAH6kLmebB@public.gmane.org;
>>>> linux- tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
>>>> Subject: Re: [tegrarcm PATCH v1 3/4] Add option --signed
>>>>
>>>> On 03/04/2016 04:44 PM, Jimmy Zhang wrote:
>>>>> This option allows user to specify and download signed rcm messages
>>>>> and bootloader to device. This option must come along with option
>>>>> "--
>>>> miniloader".
>>>>>
>>>>> Example:
>>>>> $ sudo ./tegrarcm --miniloader t124_ml_rcm.bin --signed --bct
>>>>> test.bct --bootloader u-boo
>>>>
>>>> I won't review this patch in detail since I expect it will change
>>>> quite a bit to implement 3 modes of operation:
>>>>
>>>
>>> All three modes are in place.
>>>
>>>> a) Create signed files, don't interact with HW.
>>>
>>> This is patch 2/4. Command syntax:
>>> $ sudo ./tegrarcm --ml_rcm <ml> --pkc <keyfile> --bootloader
>>> <bootloader>
>>>
>>> User still needs to put device in recovery mode so that tegrarcm can detect
>> and figure out what soc. Otherwise, we need to add one more parameter for
>> soc.
>>>
>>>> b) Read signed files, send them to HW.
>>>
>>> This is patch 3/4. Command syntax:
>>> $ sudo ./tegrarcm --miniloader <signed_ml> --signed --bct <bct>
>>> --bootloader <bootloader> --loadaddr <addr>
>>>
>>>> c) Sign data on-the-fly, while sending it to HW.
>>>
>>> This is patch 1/4. Command syntax:
>>> $ sudo ./tegrarcm --pkc <keyfile> --bct <bct> --bootloader
>>> <bootloader> --loadaddr <addr>
>>
>> OK. Updating the documentation would be useful to make this clear.
>>
>> I don't like describing the file that contains signed data as a miniloader.
>> Doesn't the file contain much more than the miniloader (IIUC, all the RCM
>> messages need to be signed, so presumably we need to pre-calculate and
>> store all RCM messages to avoid tegrarcm needing access to the PKC which is
>> the whole point of this mode of operation)? I would like to see the --
>> miniloader option reserved for the case where we allow the user to supply
>> an alternative (plain unsigned, no header) miniloader binary instead of the
>> built-in binary.
>>
>> As I probably mentioned before, the naming of --ml_rcm isn't great.
>>
>> I don't like the fact that the operational mode is derived from the set of
>> command-line arguments. I'd like the default to be to interact with HW,
>> perform signatures if required, and download data to the HW. I'd prefer the
>> other modes to be explicitly requested so it's clear what the tool will do;
>> perhaps something like:
>>
>> download unsigned:
>> tegrarcm --bootloader <bl> --loadaddr <addr>
>>
>> download with auto-signing:
>> tegrarcm --bootloader <bl> --loadaddr <addr> --pkc <pkc>
>>
>> generate signed messages:
>> tegrarcm --gen-signed-msgs --signed-msgs-file msgs.bin \
>>       --bootloader <bl> --loadaddr <addr> --pkc <pkc>
>>
> The signed messages include
> a) query version rcm
> b) download miniloader rcm
> c) bl signature
>
> During flashing, tegrarcm needs to down load these three blobs as independent binary to target at predefined flashing phase. Currently I use option "--ml_rcm" and "--bootloader" to derive filenames for these three blobs. If using one file for all, we have to come up a mechanism to pack them together during signing and unpack them when flashing. I agree with your command line parameter. But, I still prefer to create separate message files. For example, if I have a command as below:
>
>   tegrarcm --gen-signed-msgs  --signed-msgs-file rel_1001.bin \
>        --bootloader <bl> --loadaddr <addr> --pkc <pkc>
>
> I prefer to actually create files
> a) rel_1001.bin.qry for signed query version rcm
> b) rel_1001.bin.ml for signed download miniloader rcm
> c) rel_1001.bin.bl for bootloader's 256 bytes rsa_pss signature
>
> User should have doc to trace what key_file, bootloader (flasher) are used for rel_1001

That seems fine.