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

[George Dunlap <george.dunlap@xxxxxxxxxx>]

On 11/21/2017 07:21 PM, Andrew Cooper wrote:
> On 21/11/17 19:05, Ian Jackson wrote:
>> George Dunlap writes ("Re: [PATCH 10/16] SUPPORT.md: Add Debugging, 
>> analysis, crash post-portem"):
>>> gdbsx security support: Someone may want to debug an untrusted guest,
>>> so I think we should say 'yes' here.
>> I think running gdb on an potentially hostile program is foolish.
>>
>>> 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.
>> gdbsx itself is probably simple enough to be fine but I would rather
>> not call it security supported because that might encourage people to
>> use it with gdb.
>>
>> If someone wants to use gdbsx with something that's not gdb then they
>> might want to ask us to revisit that.
> 
> If gdbsx chooses (or gets tricked into using) DOMID_XEN, then it gets
> arbitrary read/write access over hypervisor virtual address space, due
> to the behaviour of the hypercalls it uses.
> 
> As a tool, it mostly functions (there are some rather sharp corners
> which I've not gotten time to fix so far), but it is definitely not
> something I would trust in a hostile environment.

Right -- "not security supported" it is. :-)

 -George

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