[PATCH bpf-next v6 3/4] bpf: support specifying ingress via xdp_md context in BPF_PROG_TEST_RUN

[Zvi Effron <zeffron@riotgames.com>]

Support specifying the ingress_ifindex and rx_queue_index of xdp_md
contexts for BPF_PROG_TEST_RUN.

The intended use case is to allow testing XDP programs that make decisions
based on the ingress interface or RX queue.

If ingress_ifindex is specified, look up the device by the provided index
in the current namespace and use its xdp_rxq for the xdp_buff. If the
rx_queue_index is out of range, or is non-zero when the ingress_ifindex is
0, return -EINVAL.

Co-developed-by: Cody Haas <chaas@riotgames.com>
Signed-off-by: Cody Haas <chaas@riotgames.com>
Co-developed-by: Lisa Watanabe <lwatanabe@riotgames.com>
Signed-off-by: Lisa Watanabe <lwatanabe@riotgames.com>
Signed-off-by: Zvi Effron <zeffron@riotgames.com>
---
 net/bpf/test_run.c | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/net/bpf/test_run.c b/net/bpf/test_run.c
index 229c5deb813c..1ba15c741517 100644
--- a/net/bpf/test_run.c
+++ b/net/bpf/test_run.c
@@ -690,15 +690,35 @@ int bpf_prog_test_run_skb(struct bpf_prog *prog, const union bpf_attr *kattr,
 
 static int xdp_convert_md_to_buff(struct xdp_md *xdp_md, struct xdp_buff *xdp)
 {
+	unsigned int ingress_ifindex, rx_queue_index;
+	struct netdev_rx_queue *rxqueue;
+	struct net_device *device;
+
 	if (!xdp_md)
 		return 0;
 
 	if (xdp_md->egress_ifindex != 0)
 		return -EINVAL;
 
-	if (xdp_md->ingress_ifindex != 0 || xdp_md->rx_queue_index != 0)
+	ingress_ifindex = xdp_md->ingress_ifindex;
+	rx_queue_index = xdp_md->rx_queue_index;
+
+	if (!ingress_ifindex && rx_queue_index)
 		return -EINVAL;
 
+	if (ingress_ifindex) {
+		device = dev_get_by_index(current->nsproxy->net_ns,
+					  ingress_ifindex);
+		if (!device)
+			return -EINVAL;
+
+		if (rx_queue_index >= device->real_num_rx_queues)
+			return -EINVAL;
+
+		rxqueue = __netif_get_rx_queue(device, rx_queue_index);
+		xdp->rxq = &rxqueue->xdp_rxq;
+	}
+
 	xdp->data = xdp->data_meta + xdp_md->data;
 
 	return 0;
-- 
2.31.1