BMC update via TFTP

[Joseph Reynolds]

On 12/11/19 5:02 AM, Alexander Tereschenko wrote:
>>> Yes, that could be a solution for the problem we discuss, providing 
>>> both integrity and confidentiality, without any major OpenBMC 
>>> development necessary - but it would mean more operational burden 
>>> for BMC admins. The problem with SCP/SFTP in this context is that 
>>> for this to work in the same manner as TFTP, the BMC must be an SSH 
>>> client - i.e. have some sort of identity/credentials for the 
>>> SCP/SFTP server provisioned first. That might not be the easiest 
>>> solution to setup, but it's of course possible and can be automated 
>>> if OpenBMC provides respective config knobs.
>>>
>>> Existing ways we have in code-update.md either don't require 
>>> credentials (TFTP), so being a client is easy, or are not making a 
>>> "client" from BMC, it's the admin who uploads stuff (SCP/REST).
>>
>> Yes, that's what I was thinking.  (And no, I am not going to 
>> recommend setting up a SCP or SFTP server that allows anonymous access.)
>>
>> This highlight the need for OpenBMC to put together a guide to 
>> provisioning your BMC.    Such as guide would give us a place to talk 
>> about uploading to the BMC SSH client certificates needed to access 
>> and download the firmware images.
>>
>> - Joseph 
>
> Agree, the provisioning guide could be a good point to have this 
> discussion. However I beieve updates in general is a broader and more 
> "operational" (i.e. "continuous" as opposed to provisioning being 
> rather "one-time") topic, so the approach in the organization/of a 
> given BMC admin can change and I believe whatever configuration 
> mechanism we develop for this (if at all), should be available at any 
> point during BMC lifetime, not only at provisioning, and be 
> architected respectively.
>

That makes sense to me.  Thanks!  I'll plan to add an item to both:
https://github.com/openbmc/docs/blob/master/security/network-security-considerations.md
and
to the threat model considerations (in review):
https://gerrit.openbmc-project.xyz/c/openbmc/docs/+/22404

- Joseph

>
> regards,
> Alexander
>
>