bpf: Fix dev's rx stats for bpf_redirect_peer traffic

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From: Peilin Ye <peilin.ye@xxxxxxxxxxxxx>

[ Upstream commit 024ee930cb3c9ae49e4266aee89cfde0ebb407e1 ]

Traffic redirected by bpf_redirect_peer() (used by recent CNIs like Cilium)
is not accounted for in the RX stats of supported devices (that is, veth
and netkit), confusing user space metrics collectors such as cAdvisor [0],
as reported by Youlun.

Fix it by calling dev_sw_netstats_rx_add() in skb_do_redirect(), to update
RX traffic counters. Devices that support ndo_get_peer_dev _must_ use the
@tstats per-CPU counters (instead of @lstats, or @dstats).

To make this more fool-proof, error out when ndo_get_peer_dev is set but
@tstats are not selected.

  [0] Specifically, the "container_network_receive_{byte,packet}s_total"
      counters are affected.

Fixes: 9aa1206e8f48 ("bpf: Add redirect_peer helper")
Reported-by: Youlun Zhang <zhangyoulun@xxxxxxxxxxxxx>
Signed-off-by: Peilin Ye <peilin.ye@xxxxxxxxxxxxx>
Co-developed-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Reviewed-by: Nikolay Aleksandrov <razor@xxxxxxxxxxxxx>
Link: https://lore.kernel.org/r/20231114004220.6495-6-daniel@xxxxxxxxxxxxx
Signed-off-by: Martin KaFai Lau <martin.lau@xxxxxxxxxx>
Signed-off-by: Daniel Borkmann <daniel@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/core/dev.c    |    8 ++++++++
 net/core/filter.c |    1 +
 2 files changed, 9 insertions(+)

--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -9995,6 +9995,14 @@ static int netdev_do_alloc_pcpu_stats(st
 {
 	void __percpu *v;
 
+	/* Drivers implementing ndo_get_peer_dev must support tstat
+	 * accounting, so that skb_do_redirect() can bump the dev's
+	 * RX stats upon network namespace switch.
+	 */
+	if (dev->netdev_ops->ndo_get_peer_dev &&
+	    dev->pcpu_stat_type != NETDEV_PCPU_STAT_TSTATS)
+		return -EOPNOTSUPP;
+
 	switch (dev->pcpu_stat_type) {
 	case NETDEV_PCPU_STAT_NONE:
 		return 0;
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2491,6 +2491,7 @@ int skb_do_redirect(struct sk_buff *skb)
 			     net_eq(net, dev_net(dev))))
 			goto out_drop;
 		skb->dev = dev;
+		dev_sw_netstats_rx_add(dev, skb->len);
 		return -EAGAIN;
 	}
 	return flags & BPF_F_NEIGH ?


Patches currently in stable-queue which might be from daniel@xxxxxxxxxxxxx are

queue-6.1/tcp_bpf-fix-the-sk_mem_uncharge-logic-in-tcp_bpf_sen.patch
queue-6.1/bpf-fix-dev-s-rx-stats-for-bpf_redirect_peer-traffic.patch
queue-6.1/bpf-remove-unnecessary-kfree-im_node-in-lpm_trie_upd.patch
queue-6.1/bpf-fix-helper-writes-to-read-only-maps.patch
queue-6.1/net-move-l-t-d-stats-allocation-to-core-and-convert-veth-vrf.patch
queue-6.1/veth-use-tstats-per-cpu-traffic-counters.patch
queue-6.1/bpf-handle-bpf_exist-and-bpf_noexist-for-lpm-trie.patch
queue-6.1/tools-override-makefile-arch-variable-if-defined-but.patch




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