[libvirt] [PATCH 3/8] qemu: don't hold both jobs for suspend

[Michal Privoznik]

On 12/5/19 5:08 PM, Jonathon Jongsma wrote:
> We have to assume that the guest agent may be malicious so we don't want
> to allow any agent queries to block any other libvirt API. By holding a
> monitor job while we're querying the agent, we open ourselves up to a
> DoS.
> 
> So split the function up a bit to only hold the monitor job while
> querying qemu for whether the domain supports suspend. Then acquire only
> an agent job while issuing the agent suspend command.
> 
> Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com>
> ---
>   src/qemu/qemu_driver.c | 93 ++++++++++++++++++++++++++----------------
>   1 file changed, 58 insertions(+), 35 deletions(-)
> 
> diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
> index edd36f4a89..e39ee2acc9 100644
> --- a/src/qemu/qemu_driver.c
> +++ b/src/qemu/qemu_driver.c
> @@ -19713,6 +19713,58 @@ qemuDomainProbeQMPCurrentMachine(virQEMUDriverPtr driver,
>   }
>   
>   
> +/* returns -1 on error, or if query is not supported, 0 if query was successful */
> +static int
> +qemuDomainQueryWakeupSuspendSupport(virQEMUDriverPtr driver,
> +                                    virDomainObjPtr vm,
> +                                    bool *wakeupSupported)
> +{
> +    int ret = -1;
> +    qemuDomainObjPrivatePtr priv = vm->privateData;

Usually, I put @ret last as it's shorter line compared to @priv.

> +
> +    if (!virQEMUCapsGet(priv->qemuCaps, QEMU_CAPS_QUERY_CURRENT_MACHINE))
> +        return ret;

s/ret/-1/

> +
> +    if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
> +        return ret;
> +

Michal