[PATCH net] virtio_net: reject XDP programs using header adjustment

commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
added a new XDP helper to prepend and remove data from a frame.
Make virtio_net reject programs making use of this helper until
proper support is added.

Signed-off-by: Jakub Kicinski <redacted>
---
 drivers/net/virtio_net.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 08327e005ccc..db761f37783e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -1677,6 +1677,11 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
 	u16 xdp_qp = 0, curr_qp;
 	int i, err;
 
+	if (prog && prog->xdp_adjust_head) {
+		netdev_warn(dev, "Does not support bpf_xdp_adjust_head()\n");
+		return -EOPNOTSUPP;
+	}
+
 	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
 	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
 		netdev_warn(dev, "can't set XDP while host is implementing LRO, disable LRO first\n");

-- 
2.11.0

commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
added a new XDP helper to prepend and remove data from a frame.
Make virtio_net reject programs making use of this helper until proper
support is added.

Signed-off-by: Jakub Kicinski <redacted>

Is that how it goes until we'll add the proper infrastructure?
Am I expected to provide the same for qede?

I was under the impression that so long as this is being [early] developed
and there's no way to communicate what is and isn't supported by
a given implementation, it would simply be the user's responsibility
to make sure what he's trying is supported.

On Mon, Dec 19, 2016 at 3:23 PM, Mintz, Yuval [off-list ref] wrote:

quoted

commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
added a new XDP helper to prepend and remove data from a frame.
Make virtio_net reject programs making use of this helper until proper
support is added.

Signed-off-by: Jakub Kicinski <redacted>

Is that how it goes until we'll add the proper infrastructure?
Am I expected to provide the same for qede?

I asked Martin to fix the existing drivers like qede but virtio's XDP
was not merged at that point.

I was under the impression that so long as this is being [early] developed
and there's no way to communicate what is and isn't supported by
a given implementation, it would simply be the user's responsibility
to make sure what he's trying is supported.

IMHO the less user has to guess the better if we're hoping for wide adoption.

On 16-12-19 07:05 AM, Jakub Kicinski wrote:

Acked-by: John Fastabend <redacted>

Thanks patch looks good. Alternatively we could push a "bug fix" to
support the adjust header feature depending on how DaveM and MST feel
about that. I don't have a strong opinion but I have the patch on my
queue it just needs some more testing. The adjust header bits were
merged in between some of the later versions of the patch which is how
this check got missed.

Thanks,
John

From: John Fastabend <john.fastabend@gmail.com>
Date: Mon, 19 Dec 2016 09:50:57 -0800

On 16-12-19 07:05 AM, Jakub Kicinski wrote:

quoted

commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
added a new XDP helper to prepend and remove data from a frame.
Make virtio_net reject programs making use of this helper until
proper support is added.

Signed-off-by: Jakub Kicinski <redacted>
---
 drivers/net/virtio_net.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 08327e005ccc..db761f37783e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -1677,6 +1677,11 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
 	u16 xdp_qp = 0, curr_qp;
 	int i, err;
 
+	if (prog && prog->xdp_adjust_head) {
+		netdev_warn(dev, "Does not support bpf_xdp_adjust_head()\n");
+		return -EOPNOTSUPP;
+	}
+
 	if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
 	    virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
 		netdev_warn(dev, "can't set XDP while host is implementing LRO, disable LRO first\n");

Acked-by: John Fastabend <redacted>

Thanks patch looks good. Alternatively we could push a "bug fix" to
support the adjust header feature depending on how DaveM and MST feel
about that. I don't have a strong opinion but I have the patch on my
queue it just needs some more testing. The adjust header bits were
merged in between some of the later versions of the patch which is how
this check got missed.

I would like to avoid inconsistent XDP feature support amongst drivers
as much as possible.

On Mon, Dec 19, 2016 at 5:50 PM, John Fastabend
[off-list ref] wrote:

On 16-12-19 07:05 AM, Jakub Kicinski wrote:

quoted

commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
added a new XDP helper to prepend and remove data from a frame.
Make virtio_net reject programs making use of this helper until
proper support is added.

Signed-off-by: Jakub Kicinski <redacted>
---
 drivers/net/virtio_net.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 08327e005ccc..db761f37783e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -1677,6 +1677,11 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
      u16 xdp_qp = 0, curr_qp;
      int i, err;

+     if (prog && prog->xdp_adjust_head) {
+             netdev_warn(dev, "Does not support bpf_xdp_adjust_head()\n");
+             return -EOPNOTSUPP;
+     }
+
      if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
          virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
              netdev_warn(dev, "can't set XDP while host is implementing LRO, disable LRO first\n");

Acked-by: John Fastabend <redacted>

Thanks patch looks good. Alternatively we could push a "bug fix" to
support the adjust header feature depending on how DaveM and MST feel
about that. I don't have a strong opinion but I have the patch on my
queue it just needs some more testing.

Cool!  I thought to ask you what your plans are but then this patch is so
trivial I decided to just post it :) I'm perfectly happy with dropping it
for now and reposting after ~rc5 if needed.

On 16-12-20 04:30 AM, Jakub Kicinski wrote:

On Mon, Dec 19, 2016 at 5:50 PM, John Fastabend
[off-list ref] wrote:

quoted

On 16-12-19 07:05 AM, Jakub Kicinski wrote:

quoted

commit 17bedab27231 ("bpf: xdp: Allow head adjustment in XDP prog")
added a new XDP helper to prepend and remove data from a frame.
Make virtio_net reject programs making use of this helper until
proper support is added.

Signed-off-by: Jakub Kicinski <redacted>
---
 drivers/net/virtio_net.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
index 08327e005ccc..db761f37783e 100644
--- a/drivers/net/virtio_net.c
+++ b/drivers/net/virtio_net.c

@@ -1677,6 +1677,11 @@ static int virtnet_xdp_set(struct net_device *dev, struct bpf_prog *prog)
      u16 xdp_qp = 0, curr_qp;
      int i, err;

+     if (prog && prog->xdp_adjust_head) {
+             netdev_warn(dev, "Does not support bpf_xdp_adjust_head()\n");
+             return -EOPNOTSUPP;
+     }
+
      if (virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO4) ||
          virtio_has_feature(vi->vdev, VIRTIO_NET_F_GUEST_TSO6)) {
              netdev_warn(dev, "can't set XDP while host is implementing LRO, disable LRO first\n");

Acked-by: John Fastabend <redacted>

Thanks patch looks good. Alternatively we could push a "bug fix" to
support the adjust header feature depending on how DaveM and MST feel
about that. I don't have a strong opinion but I have the patch on my
queue it just needs some more testing.

Cool!  I thought to ask you what your plans are but then this patch is so
trivial I decided to just post it :) I'm perfectly happy with dropping it
for now and reposting after ~rc5 if needed.

Hi Jakub,

I just posted a RFC take a look if you get a chance. Notice though Jason
fixed up my linearize path a bunch so it will need to be pushed on top
of that series.

Thanks,
John