Re: [Qemu-devel] [PATCH 1/3] NBD proto: forbid TRIM command without negotiation

[Eric Blake <eblake@redhat.com>]

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On 03/28/2016 04:43 AM, Denis V. Lunev wrote:
> From: Pavel Borzenkov <pborzenkov@virtuozzo.com>
> 
> There is a loophole in the protocol that allows a client to send TRIM
> request even if support for it wasn't negotiated with the server. State
> explicitly that the client MUST NOT send such command without prior
> successful negotiation.
> 
> Signed-off-by: Pavel Borzenkov <pborzenkov@virtuozzo.com>
> Reviewed-by: Roman Kagan <rkagan@virtuozzo.com>
> Signed-off-by: Denis V. Lunev <den@openvz.org>
> CC: Wouter Verhelst <w@uter.be>
> CC: Eric Blake <eblake@redhat.com>
> CC: Alex Bligh <alex@alex.org.uk>
> ---
>  doc/proto.md | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/doc/proto.md b/doc/proto.md
> index 6d1cb34..d54ed19 100644
> --- a/doc/proto.md
> +++ b/doc/proto.md
> @@ -471,6 +471,9 @@ The following request types exist:
>      about the contents of the export affected by this command, until
>      overwriting it again with `NBD_CMD_WRITE`.
>  
> +    A client MUST NOT send a trim request unless `NBD_FLAG_SEND_TRIM`
> +    was set in the export flags field.
> +

Do we also want to mention that the server SHOULD fail with EINVAL if
the client sends it anyway, and similarly if NBD_CMD_FLUSH was sent
without the appropriate export flag (but that the client should not rely
on that particular failure)?

But as this is a strict improvement,
Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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