Michael S. Tsirkin
2022-Jun-17 10:01 UTC
[PATCH] virtio: disable notification hardening by default
On Fri, Jun 17, 2022 at 03:26:26PM +0800, Jason Wang wrote:> We try to harden virtio device notifications in 8b4ec69d7e09 ("virtio: > harden vring IRQ"). It works with the assumption that the driver or > core can properly call virtio_device_ready() at the right > place. Unfortunately, this seems to be not true and uncover various > bugs of the existing drivers, mainly the issue of using > virtio_device_ready() incorrectly. > > So let's having a Kconfig option and disable it by default. It gives > us a breath to fix the drivers and then we can consider to enable it > by default. > > Signed-off-by: Jason Wang <jasowang at redhat.com>Do you want to drop irq_lock lock/unlock in ccw too?> --- > drivers/virtio/Kconfig | 6 ++++++ > drivers/virtio/virtio.c | 2 ++ > drivers/virtio/virtio_ring.c | 12 ++++++++++++ > include/linux/virtio_config.h | 2 ++ > 4 files changed, 22 insertions(+) > > diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig > index b5adf6abd241..b059c39af3d4 100644 > --- a/drivers/virtio/Kconfig > +++ b/drivers/virtio/Kconfig > @@ -35,6 +35,12 @@ menuconfig VIRTIO_MENU > > if VIRTIO_MENU > > +config VIRTIO_HARDEN_NOTIFICATION > + bool "Harden virtio notification" > + help > + Enable to this to harden the device notifications and > + supress the ones that are illegal. > + > config VIRTIO_PCI > tristate "PCI driver for virtio devices" > depends on PCI > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > index ef04a96942bf..21dc08d2f32d 100644 > --- a/drivers/virtio/virtio.c > +++ b/drivers/virtio/virtio.c > @@ -220,6 +220,7 @@ static int virtio_features_ok(struct virtio_device *dev) > * */ > void virtio_reset_device(struct virtio_device *dev) > { > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > /* > * The below virtio_synchronize_cbs() guarantees that any > * interrupt for this line arriving after > @@ -228,6 +229,7 @@ void virtio_reset_device(struct virtio_device *dev) > */ > virtio_break_device(dev); > virtio_synchronize_cbs(dev); > +#endif > > dev->config->reset(dev); > } > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index 13a7348cedff..d9d3b6e201fb 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -1688,7 +1688,11 @@ static struct virtqueue *vring_create_virtqueue_packed( > vq->we_own_ring = true; > vq->notify = notify; > vq->weak_barriers = weak_barriers; > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > vq->broken = true; > +#else > + vq->broken = false; > +#endif > vq->last_used_idx = 0; > vq->event_triggered = false; > vq->num_added = 0; > @@ -2135,9 +2139,13 @@ irqreturn_t vring_interrupt(int irq, void *_vq) > } > > if (unlikely(vq->broken)) { > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > dev_warn_once(&vq->vq.vdev->dev, > "virtio vring IRQ raised before DRIVER_OK"); > return IRQ_NONE; > +#else > + return IRQ_HANDLED; > +#endif > } > > /* Just a hint for performance: so it's ok that this can be racy! */ > @@ -2180,7 +2188,11 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index, > vq->we_own_ring = false; > vq->notify = notify; > vq->weak_barriers = weak_barriers; > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > vq->broken = true; > +#else > + vq->broken = false; > +#endif > vq->last_used_idx = 0; > vq->event_triggered = false; > vq->num_added = 0; > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > index 9a36051ceb76..d15c3cdda2d2 100644 > --- a/include/linux/virtio_config.h > +++ b/include/linux/virtio_config.h > @@ -257,6 +257,7 @@ void virtio_device_ready(struct virtio_device *dev) > > WARN_ON(status & VIRTIO_CONFIG_S_DRIVER_OK); > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > /* > * The virtio_synchronize_cbs() makes sure vring_interrupt() > * will see the driver specific setup if it sees vq->broken > @@ -264,6 +265,7 @@ void virtio_device_ready(struct virtio_device *dev) > */ > virtio_synchronize_cbs(dev); > __virtio_unbreak_device(dev); > +#endif > /* > * The transport should ensure the visibility of vq->broken > * before setting DRIVER_OK. See the comments for the transport > -- > 2.25.1
Jason Wang
2022-Jun-17 11:47 UTC
[PATCH] virtio: disable notification hardening by default
On Fri, Jun 17, 2022 at 6:01 PM Michael S. Tsirkin <mst at redhat.com> wrote:> > On Fri, Jun 17, 2022 at 03:26:26PM +0800, Jason Wang wrote: > > We try to harden virtio device notifications in 8b4ec69d7e09 ("virtio: > > harden vring IRQ"). It works with the assumption that the driver or > > core can properly call virtio_device_ready() at the right > > place. Unfortunately, this seems to be not true and uncover various > > bugs of the existing drivers, mainly the issue of using > > virtio_device_ready() incorrectly. > > > > So let's having a Kconfig option and disable it by default. It gives > > us a breath to fix the drivers and then we can consider to enable it > > by default. > > > > Signed-off-by: Jason Wang <jasowang at redhat.com> > > > Do you want to drop irq_lock lock/unlock in ccw too?Not a must I think. But if you insist, I can remove them. Thanks> > > --- > > drivers/virtio/Kconfig | 6 ++++++ > > drivers/virtio/virtio.c | 2 ++ > > drivers/virtio/virtio_ring.c | 12 ++++++++++++ > > include/linux/virtio_config.h | 2 ++ > > 4 files changed, 22 insertions(+) > > > > diff --git a/drivers/virtio/Kconfig b/drivers/virtio/Kconfig > > index b5adf6abd241..b059c39af3d4 100644 > > --- a/drivers/virtio/Kconfig > > +++ b/drivers/virtio/Kconfig > > @@ -35,6 +35,12 @@ menuconfig VIRTIO_MENU > > > > if VIRTIO_MENU > > > > +config VIRTIO_HARDEN_NOTIFICATION > > + bool "Harden virtio notification" > > + help > > + Enable to this to harden the device notifications and > > + supress the ones that are illegal. > > + > > config VIRTIO_PCI > > tristate "PCI driver for virtio devices" > > depends on PCI > > diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c > > index ef04a96942bf..21dc08d2f32d 100644 > > --- a/drivers/virtio/virtio.c > > +++ b/drivers/virtio/virtio.c > > @@ -220,6 +220,7 @@ static int virtio_features_ok(struct virtio_device *dev) > > * */ > > void virtio_reset_device(struct virtio_device *dev) > > { > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > /* > > * The below virtio_synchronize_cbs() guarantees that any > > * interrupt for this line arriving after > > @@ -228,6 +229,7 @@ void virtio_reset_device(struct virtio_device *dev) > > */ > > virtio_break_device(dev); > > virtio_synchronize_cbs(dev); > > +#endif > > > > dev->config->reset(dev); > > } > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > > index 13a7348cedff..d9d3b6e201fb 100644 > > --- a/drivers/virtio/virtio_ring.c > > +++ b/drivers/virtio/virtio_ring.c > > @@ -1688,7 +1688,11 @@ static struct virtqueue *vring_create_virtqueue_packed( > > vq->we_own_ring = true; > > vq->notify = notify; > > vq->weak_barriers = weak_barriers; > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > vq->broken = true; > > +#else > > + vq->broken = false; > > +#endif > > vq->last_used_idx = 0; > > vq->event_triggered = false; > > vq->num_added = 0; > > @@ -2135,9 +2139,13 @@ irqreturn_t vring_interrupt(int irq, void *_vq) > > } > > > > if (unlikely(vq->broken)) { > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > dev_warn_once(&vq->vq.vdev->dev, > > "virtio vring IRQ raised before DRIVER_OK"); > > return IRQ_NONE; > > +#else > > + return IRQ_HANDLED; > > +#endif > > } > > > > /* Just a hint for performance: so it's ok that this can be racy! */ > > @@ -2180,7 +2188,11 @@ struct virtqueue *__vring_new_virtqueue(unsigned int index, > > vq->we_own_ring = false; > > vq->notify = notify; > > vq->weak_barriers = weak_barriers; > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > vq->broken = true; > > +#else > > + vq->broken = false; > > +#endif > > vq->last_used_idx = 0; > > vq->event_triggered = false; > > vq->num_added = 0; > > diff --git a/include/linux/virtio_config.h b/include/linux/virtio_config.h > > index 9a36051ceb76..d15c3cdda2d2 100644 > > --- a/include/linux/virtio_config.h > > +++ b/include/linux/virtio_config.h > > @@ -257,6 +257,7 @@ void virtio_device_ready(struct virtio_device *dev) > > > > WARN_ON(status & VIRTIO_CONFIG_S_DRIVER_OK); > > > > +#ifdef CONFIG_VIRTIO_HARDEN_NOTIFICATION > > /* > > * The virtio_synchronize_cbs() makes sure vring_interrupt() > > * will see the driver specific setup if it sees vq->broken > > @@ -264,6 +265,7 @@ void virtio_device_ready(struct virtio_device *dev) > > */ > > virtio_synchronize_cbs(dev); > > __virtio_unbreak_device(dev); > > +#endif > > /* > > * The transport should ensure the visibility of vq->broken > > * before setting DRIVER_OK. See the comments for the transport > > -- > > 2.25.1 >