[U-Boot] Password protection of U-Boot command line

[Graeme Russ]

Hi Wolfgang,

On 02/10/2012 10:38 PM, Wolfgang Denk wrote:
> Dear Graeme Russ,
> 
> In message <CALButCLT2o=7QO4GbM0M5Tp3BYXPCpqr7Sx6WYH09JKcUdMFSA at mail.gmail.com> you wrote:
>>
>> As an adjunct to a recent discussion, I wonder if there would be much
>> point in password protecting access to the U-Boot command line. The
>> password could be saved in an environment variable as an MD-5 or SHA-256
>> hash.
> 
> We already have such protection, even if it's very simplistic: see
> doc/README.autoboot (search for CONFIG_AUTOBOOT_DELAY_STR,
> CONFIG_AUTOBOOT_STOP_STR resp. "bootdelaykey" and "bootstopkey").

OK, so the thought of protecting the shell with a password has already
happened...But the implementation is to hard-code the password in the
U-Boot image or to have it unencrypted in the environment

I think we can agree that there is room for improvement :)

>> But I wonder if:
>>
>>  a) It's worth it, and;
>>  b) If it would be secure anyway...
>>
>> When U-Boot environment editing tools available in the host OS, it would
>> be fairly trivial to overwrite the password variable - Unless, of course,
>> the host OS did not support that functionality.
>>
>> This feature may be usefull for devices where every part of the system
>> must be tightly controlled (medical devices, voting machines etc)
> 
> Well, in such devices you will typically disable interactive access at
> all.

Yes, but if you don't allow setting of environment variables from the host
OS, how can you change the settings if you need to

Sounds like it's not a 'completely ruled out' idea...

Regards,

Graeme