On Fri, Jul 27, 2012 at 6:26 PM, Anton Vorontsov cbouatmailru@gmail.com wrote: <snip long rant>
But if you say that it wasn't the case, and no one thought about the reducing the debugger in the "evil" way, so be it, I trust you. But I still don't trust the phone vendors. They showed their bad attitude in many ways towards hackers, so I think we both have quite legitimate reasons to be a little bit paranoid. :-)
I've never seen a non-Nexus phone that used the FIQ debugger, and I believe every Nexus device has supported rooting. We leave the FIQ debugger enabled on the devices we personally carry because it allows easy debugging without compromising our data, and we leave it enabled on production devices (and leave the serial console muxed out the headphone jack) because it's more useful to end users than a blank serial console.
An alternate option would be to allow userspace to write a password hash to a sysfs file, and require the password to be entered over the serial console to unlock KGDB or enable unsafe KGDB commands.
Yup, that's a very nice idea. This can be implemented by introducing "unlock" KDB command. Although, that also requires tight integration w/ user-space, i.e. on boot userland would need to supply hashing method, salt and root's password hash. The same has to be done on every password change. It is surely doable, but not sure if it is worth the efforts. Maybe, some day.
Thanks,
-- Anton Vorontsov Email: cbouatmailru@gmail.com