On Fri, 10 Nov 2017, David Howells wrote:

quoted

I fail to see how this fits into the secure boot security model, could you 
please explain?

The idea is to prevent cryptographic data for filesystems and other things
from being read out of the kernel memory as well as to prevent unauthorised
modification of kernel memory.

Then it would make sense to actually lock down dumping of registers / 
function arguments (kprobes can currently do that, ftrace eventually could 
as well I guess), but disabling the whole ftrace altogether seems like a 
totally unnecessary overkill.

quoted

Secure boot is about having a constant proof / verification that the code 
you're running in ring0 can be trusted (IOW is the one that has been 
signed and verified by the whole boot chain).

Checking execution patterns doesn't seem to fit at all.

I'll defer this question to Alexei since he suggested I needed to deal 
with this too.

Thanks.

-- 
Jiri Kosina
SUSE Labs

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