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SubjectRe: [dm-devel] [PATCH 1/2] Fail I/O to thin pool devices
From
Dne 07. 02. 23 v 17:19 Demi Marie Obenour napsal(a):
> On Tue, Feb 07, 2023 at 03:02:51PM +0000, Joe Thornber wrote:
>> Nack.
>>
>> I don't see the security issue; how is this any different from running the
>> thin tools on any incorrect device? Or even the data device that the pool
>> is mirroring.
>
> I special-cased the pool device for two reasons:
>
> 1. I have run the thin tools on the pool device myself before realising
> that they needed to be run on the metadata device. It took me a
> while to realize that I was using the wrong device. I have not made
> that mistake with other devices, which is why I special-cased the
> pool device in this patch.
>
> 2. Doing I/O to the pool device is pointless. The pool device is
> strictly slower than the data device and exposes the exact same
> contents, so accessing the pool device directly is never what one
> wants.
>
> If there are backwards compatibility concerns, I could make this be
> controlled by a Kconfig option, module parameter, or both.
>
>> In general the thin tools don't modify the metadata they're
>> running on. If you know of a security issue with the thin tools please let
>> me know.
>
> I am not aware of a concrete security problem, but in general I prefer
> not to expose unnecessary attack surface.

lvm2 introduced 'protection' layer device - which keeps -tpool opened and
thus avoid possibility to use i.e. mkfs on thin-pool itself (as it requires
exclusive open)

Zdenek

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