Re: [Xen-devel] [PATCH 10/16] SUPPORT.md: Add Debugging, analysis, crash post-portem

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 11/21/2017 08:48 AM, Jan Beulich wrote:
>>>> On 13.11.17 at 16:41, <george.dunlap@xxxxxxxxxx> wrote:
>> --- a/SUPPORT.md
>> +++ b/SUPPORT.md
>> @@ -152,6 +152,35 @@ Output of information in machine-parseable JSON format
>>  
>>      Status: Supported, Security support external
>>  
>> +## Debugging, analysis, and crash post-mortem
>> +
>> +### gdbsx
>> +
>> +    Status, x86: Supported
>> +
>> +Debugger to debug ELF guests
>> +
>> +### Soft-reset for PV guests
>> +
>> +    Status: Supported
>> +    
>> +Soft-reset allows a new kernel to start 'from scratch' with a fresh VM 
>> state, 
>> +but with all the memory from the previous state of the VM intact.
>> +This is primarily designed to allow "crash kernels", 
>> +which can do core dumps of memory to help with debugging in the event of a 
>> crash.
>> +
>> +### xentrace
>> +
>> +    Status, x86: Supported
>> +
>> +Tool to capture Xen trace buffer data
>> +
>> +### gcov
>> +
>> +    Status: Supported, Not security supported
> 
> I agree with excluding security support here, but why wouldn't the
> same be the case for gdbsx and xentrace?

From my initial post:

---

gdbsx security support: Someone may want to debug an untrusted guest,
so I think we should say 'yes' here.

xentrace: Users may want to trace guests in production environments,
so I think we should say 'yes'.

gcov: No good reason to run a gcov hypervisor in a production
environment.  May be ways for a rogue guest to DoS.

---

xentrace I would argue for security support; I've asked customers to
send me xentrace data as part of analysis before.  I also know enough
about it that I'm reasonably confident the risk of an attack vector is
pretty low.

I don't have a strong opinion on gdbsx; I'd call it 'supported', but if
you think we need to exclude it from security support I'm happy with
that as well.

 -George

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