[PATCH net-next v2 03/15] net: Add peer info to queue-get response

[Daniel Borkmann <daniel@iogearbox.net>]

From: David Wei <dw@davidwei.uk>

Add a nested peer field to the queue-get response that returns the peered
ifindex and queue id.

Example with ynl client:

  # ip netns exec foo ./pyynl/cli.py \
      --spec ~/netlink/specs/netdev.yaml \
      --do queue-get \
      --json '{"ifindex": 3, "id": 1, "type": "rx"}'
  {'id': 1, 'ifindex': 3, 'peer': {'id': 15, 'ifindex': 4, 'netns-id': 21}, 'type': 'rx'}

Note that the caller of netdev_nl_queue_fill_one() holds the netdevice
lock. For the queue-get we do not lock both devices. When queues get
{un,}peered, both devices are locked, thus if netdev_rx_queue_peered()
returns true, the peer pointer points to a valid device. The netns-id
is fetched via peernet2id_alloc() similarly as done in OVS.

Signed-off-by: David Wei <dw@davidwei.uk>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
 Documentation/netlink/specs/netdev.yaml | 24 ++++++++++++++++++
 include/net/netdev_rx_queue.h           |  3 +++
 include/uapi/linux/netdev.h             | 10 ++++++++
 net/core/netdev-genl.c                  | 33 +++++++++++++++++++++++--
 net/core/netdev_rx_queue.c              |  8 ++++++
 tools/include/uapi/linux/netdev.h       | 10 ++++++++
 6 files changed, 86 insertions(+), 2 deletions(-)

diff --git a/Documentation/netlink/specs/netdev.yaml b/Documentation/netlink/specs/netdev.yaml
index 20bb00b7e9ac..a3c562dfd205 100644
--- a/Documentation/netlink/specs/netdev.yaml
+++ b/Documentation/netlink/specs/netdev.yaml
@@ -297,6 +297,24 @@ attribute-sets:
   -
     name: xsk-info
     attributes: []
+  -
+    name: peer-info
+    attributes:
+      -
+        name: id
+        doc: Queue index of the netdevice to which the peer queue belongs.
+        type: u32
+      -
+        name: ifindex
+        doc: ifindex of the netdevice to which the peer queue belongs.
+        type: u32
+      -
+        name: netns-id
+        doc: |
+          Network namespace of the netdevice to which the peer queue belongs.
+          This is populated if the netdevices are not in the same network
+          namespace.
+        type: s32
   -
     name: queue
     attributes:
@@ -338,6 +356,11 @@ attribute-sets:
         doc: XSK information for this queue, if any.
         type: nest
         nested-attributes: xsk-info
+      -
+        name: peer
+        doc: Whether this queue was bound to another peer queue.
+        type: nest
+        nested-attributes: peer-info
   -
     name: qstats
     doc: |
@@ -723,6 +746,7 @@ operations:
             - dmabuf
             - io-uring
             - xsk
+            - peer
       dump:
         request:
           attributes:
diff --git a/include/net/netdev_rx_queue.h b/include/net/netdev_rx_queue.h
index db3ef94c0744..ea23cca947bb 100644
--- a/include/net/netdev_rx_queue.h
+++ b/include/net/netdev_rx_queue.h
@@ -90,4 +90,7 @@ struct netdev_rx_queue *
 netif_get_rx_queue_peer_locked(struct net_device **dev,
 			       unsigned int *rxq_idx,
 			       bool *needs_unlock);
+struct netdev_rx_queue *
+netif_get_rx_queue_peer_any(struct net_device **dev,
+			    unsigned int *rxq_idx);
 #endif /* _LINUX_NETDEV_RX_QUEUE_H */
diff --git a/include/uapi/linux/netdev.h b/include/uapi/linux/netdev.h
index 4ef04d0bc412..d4d5d9f86eee 100644
--- a/include/uapi/linux/netdev.h
+++ b/include/uapi/linux/netdev.h
@@ -150,6 +150,15 @@ enum {
 	NETDEV_A_XSK_INFO_MAX = (__NETDEV_A_XSK_INFO_MAX - 1)
 };
 
+enum {
+	NETDEV_A_PEER_INFO_ID = 1,
+	NETDEV_A_PEER_INFO_IFINDEX,
+	NETDEV_A_PEER_INFO_NETNS_ID,
+
+	__NETDEV_A_PEER_INFO_MAX,
+	NETDEV_A_PEER_INFO_MAX = (__NETDEV_A_PEER_INFO_MAX - 1)
+};
+
 enum {
 	NETDEV_A_QUEUE_ID = 1,
 	NETDEV_A_QUEUE_IFINDEX,
@@ -158,6 +167,7 @@ enum {
 	NETDEV_A_QUEUE_DMABUF,
 	NETDEV_A_QUEUE_IO_URING,
 	NETDEV_A_QUEUE_XSK,
+	NETDEV_A_QUEUE_PEER,
 
 	__NETDEV_A_QUEUE_MAX,
 	NETDEV_A_QUEUE_MAX = (__NETDEV_A_QUEUE_MAX - 1)
diff --git a/net/core/netdev-genl.c b/net/core/netdev-genl.c
index 579469abac8c..28658b5cd7a4 100644
--- a/net/core/netdev-genl.c
+++ b/net/core/netdev-genl.c
@@ -393,6 +393,7 @@ netdev_nl_queue_fill_one(struct sk_buff *rsp, struct net_device *netdev,
 	struct pp_memory_provider_params *params;
 	struct netdev_rx_queue *rxq;
 	struct netdev_queue *txq;
+	struct nlattr *nest;
 	void *hdr;
 
 	hdr = genlmsg_iput(rsp, info);
@@ -410,6 +411,34 @@ netdev_nl_queue_fill_one(struct sk_buff *rsp, struct net_device *netdev,
 		if (nla_put_napi_id(rsp, rxq->napi))
 			goto nla_put_failure;
 
+		if (netdev_rx_queue_peered(netdev, q_idx)) {
+			struct net_device *p_netdev = netdev;
+			struct net *net, *p_net;
+			u32 p_q_idx = q_idx;
+
+			nest = nla_nest_start(rsp, NETDEV_A_QUEUE_PEER);
+			if (!nest)
+				goto nla_put_failure;
+
+			netif_get_rx_queue_peer_any(&p_netdev, &p_q_idx);
+			if (nla_put_u32(rsp, NETDEV_A_PEER_INFO_ID, p_q_idx) ||
+			    nla_put_u32(rsp, NETDEV_A_PEER_INFO_IFINDEX,
+					READ_ONCE(p_netdev->ifindex)))
+				goto nla_put_failure;
+
+			rcu_read_lock();
+			p_net = dev_net_rcu(p_netdev);
+			net = dev_net_rcu(netdev);
+			if (!net_eq(net, p_net)) {
+				s32 id = peernet2id_alloc(net, p_net, GFP_ATOMIC);
+
+				if (nla_put_s32(rsp, NETDEV_A_PEER_INFO_NETNS_ID, id))
+					goto nla_put_failure_unlock;
+			}
+			rcu_read_unlock();
+			nla_nest_end(rsp, nest);
+		}
+
 		params = &rxq->mp_params;
 		if (params->mp_ops &&
 		    params->mp_ops->nl_fill(params->mp_priv, rsp, rxq))
@@ -419,7 +448,6 @@ netdev_nl_queue_fill_one(struct sk_buff *rsp, struct net_device *netdev,
 			if (nla_put_empty_nest(rsp, NETDEV_A_QUEUE_XSK))
 				goto nla_put_failure;
 #endif
-
 		break;
 	case NETDEV_QUEUE_TYPE_TX:
 		txq = netdev_get_tx_queue(netdev, q_idx);
@@ -434,9 +462,10 @@ netdev_nl_queue_fill_one(struct sk_buff *rsp, struct net_device *netdev,
 	}
 
 	genlmsg_end(rsp, hdr);
-
 	return 0;
 
+nla_put_failure_unlock:
+	rcu_read_unlock();
 nla_put_failure:
 	genlmsg_cancel(rsp, hdr);
 	return -EMSGSIZE;
diff --git a/net/core/netdev_rx_queue.c b/net/core/netdev_rx_queue.c
index 85cf1b3749ee..686a6300df78 100644
--- a/net/core/netdev_rx_queue.c
+++ b/net/core/netdev_rx_queue.c
@@ -77,6 +77,14 @@ netif_get_rx_queue_peer_locked(struct net_device **dev, unsigned int *rxq_idx,
 	return rxq;
 }
 
+struct netdev_rx_queue *
+netif_get_rx_queue_peer_any(struct net_device **dev, unsigned int *rxq_idx)
+{
+	netdev_assert_locked(*dev);
+	/* Retrieves both virt-to-phys and phys-to-virt peering. */
+	return __netif_get_rx_queue_peer(dev, rxq_idx, false);
+}
+
 int netdev_rx_queue_restart(struct net_device *dev, unsigned int rxq_idx)
 {
 	struct netdev_rx_queue *rxq = __netif_get_rx_queue(dev, rxq_idx);
diff --git a/tools/include/uapi/linux/netdev.h b/tools/include/uapi/linux/netdev.h
index 4ef04d0bc412..d4d5d9f86eee 100644
--- a/tools/include/uapi/linux/netdev.h
+++ b/tools/include/uapi/linux/netdev.h
@@ -150,6 +150,15 @@ enum {
 	NETDEV_A_XSK_INFO_MAX = (__NETDEV_A_XSK_INFO_MAX - 1)
 };
 
+enum {
+	NETDEV_A_PEER_INFO_ID = 1,
+	NETDEV_A_PEER_INFO_IFINDEX,
+	NETDEV_A_PEER_INFO_NETNS_ID,
+
+	__NETDEV_A_PEER_INFO_MAX,
+	NETDEV_A_PEER_INFO_MAX = (__NETDEV_A_PEER_INFO_MAX - 1)
+};
+
 enum {
 	NETDEV_A_QUEUE_ID = 1,
 	NETDEV_A_QUEUE_IFINDEX,
@@ -158,6 +167,7 @@ enum {
 	NETDEV_A_QUEUE_DMABUF,
 	NETDEV_A_QUEUE_IO_URING,
 	NETDEV_A_QUEUE_XSK,
+	NETDEV_A_QUEUE_PEER,
 
 	__NETDEV_A_QUEUE_MAX,
 	NETDEV_A_QUEUE_MAX = (__NETDEV_A_QUEUE_MAX - 1)
-- 
2.43.0