On 1/30/25 11:21 PM, Bastien Curutchet (eBPF Foundation) wrote:
+#define BROADCAST_REDIRECT_SKEL_NB     2
+static void xdp_veth_broadcast_redirect(u32 attach_flags, u64 redirect_flags)
+{
+       struct prog_configuration prog_cfg[VETH_PAIRS_COUNT] = {
+               {
+                       .local_name = "xdp_redirect_map_multi_prog",
+                       .remote_name = "xdp_count_0",
+                       .local_flags = attach_flags,
+                       .remote_flags = attach_flags,
+               },
+               {
+                       .local_name = "xdp_redirect_map_multi_prog",
+                       .remote_name = "xdp_count_1",
+                       .local_flags = attach_flags,
+                       .remote_flags = attach_flags,
+               },
+               {
+                       .local_name = "xdp_redirect_map_multi_prog",
+                       .remote_name = "xdp_count_2",
+                       .local_flags = attach_flags,
+                       .remote_flags = attach_flags,
+               }
+       };
+       struct bpf_object *bpf_objs[BROADCAST_REDIRECT_SKEL_NB];
+       struct xdp_redirect_multi_kern *xdp_redirect_multi_kern;
+       struct veth_configuration net_config[VETH_PAIRS_COUNT];
+       struct xdp_redirect_map *xdp_redirect_map;
+       struct bpf_devmap_val devmap_val = {};
+       u16 protocol = ETH_P_IP;
+       int group_map;
+       int flags_map;
+       int cnt_map;
+       u64 cnt = 0;
+       int i, err;
+
+       xdp_redirect_multi_kern = xdp_redirect_multi_kern__open_and_load();
+       if (!ASSERT_OK_PTR(xdp_redirect_multi_kern, 
"xdp_redirect_multi_kern__open_and_load"))
+               return;
+
+       xdp_redirect_map = xdp_redirect_map__open_and_load();
+       if (!ASSERT_OK_PTR(xdp_redirect_map, "xdp_redirect_map__open_and_load"))
+               goto destroy_xdp_redirect_multi_kern;
+
+       if (!ASSERT_OK(create_network(net_config), "create network"))
+               goto destroy_xdp_redirect_map;
+
+       group_map = bpf_map__fd(xdp_redirect_multi_kern->maps.map_all);
+       if (!ASSERT_OK_FD(group_map, "open map_all"))
+               goto destroy_xdp_redirect_map;
+
+       flags_map = bpf_map__fd(xdp_redirect_multi_kern->maps.redirect_flags);
+       if (!ASSERT_OK_FD(group_map, "open map_all"))
+               goto destroy_xdp_redirect_map;
+
+       err = bpf_map_update_elem(flags_map, &protocol, &redirect_flags, 
BPF_NOEXIST);
+       if (!ASSERT_OK(err, "init IP count"))
+               goto destroy_xdp_redirect_map;
+
+       cnt_map = bpf_map__fd(xdp_redirect_map->maps.rxcnt);
+       if (!ASSERT_OK_FD(cnt_map, "open rxcnt map"))
+               goto destroy_xdp_redirect_map;
+
+       bpf_objs[0] = xdp_redirect_multi_kern->obj;
+       bpf_objs[1] = xdp_redirect_map->obj;
+       for (i = 0; i < VETH_PAIRS_COUNT; i++) {
+               int ifindex = if_nametoindex(net_config[i].local_veth);
+
+               if (attach_programs_to_veth_pair(bpf_objs, 
BROADCAST_REDIRECT_SKEL_NB,
+                                                net_config, prog_cfg, i))
+                       goto destroy_xdp_redirect_map;
+
+               SYS(destroy_xdp_redirect_map,
+                   "ip -n %s neigh add %s lladdr 00:00:00:00:00:01 dev %s",
+                   net_config[i].namespace, IP_NEIGH, 
net_config[i].remote_veth);
+
+               devmap_val.ifindex = ifindex;
+               err = bpf_map_update_elem(group_map, &ifindex, &devmap_val, 0);

I ran this test in a loop and failed at this line permanently (errno E2BIG -7) after enough iterations. I believe the problem is the group_map (aka "map_all" in the BPF program) has a max_entries 1024 and ifindex can go beyond 1024 after some "./test_progs" iterations. Understood that it is likely an existing assumption in the "map_all" definition but it needs to be addressed first before moving to test_progs.

+               if (!ASSERT_OK(err, "bpf_map_update_elem"))
+                       goto destroy_xdp_redirect_map;
+
+       }
+
+       SYS_NOFAIL("ip netns exec %s ping %s -i 0.1 -c 4 -W1 > /dev/null ",
+                   net_config[0].namespace, IP_NEIGH);
+
+       for (i = 0; i < VETH_PAIRS_COUNT; i++) {
+               err =  bpf_map_lookup_elem(cnt_map, &i, &cnt);
+               if (!ASSERT_OK(err, "get IP cnt"))
+                       goto destroy_xdp_redirect_map;
+
+               if (redirect_flags & BPF_F_EXCLUDE_INGRESS)
+                       /* veth11 shouldn't receive the ICMP requests;
+                        * others should
+                        */
+                       ASSERT_EQ(cnt, i ? 4 : 0, "compare IP cnt");
+               else
+                       /* All remote veth should receive the ICMP requests */
+                       ASSERT_EQ(cnt, 4, "compare IP cnt");
+       }
+
+destroy_xdp_redirect_map:
+       xdp_redirect_map__destroy(xdp_redirect_map);
+destroy_xdp_redirect_multi_kern:
+       xdp_redirect_multi_kern__destroy(xdp_redirect_multi_kern);
+
+       cleanup_network(net_config);
+}
+
  void test_xdp_veth_redirect(void)
  {
        if (test__start_subtest("0"))
@@ -284,3 +411,26 @@ void test_xdp_veth_redirect(void)
        if (test__start_subtest("SKB_MODE"))
                xdp_veth_redirect(XDP_FLAGS_SKB_MODE);
  }
+
+void test_xdp_veth_broadcast_redirect(void)
+{
+       if (test__start_subtest("0/BROADCAST"))
+               xdp_veth_broadcast_redirect(0, BPF_F_BROADCAST);
+
+       if (test__start_subtest("0/(BROADCAST | EXCLUDE_INGRESS)"))
+               xdp_veth_broadcast_redirect(0, BPF_F_BROADCAST | 
BPF_F_EXCLUDE_INGRESS);
+
+       if (test__start_subtest("DRV_MODE/BROADCAST"))
+               xdp_veth_broadcast_redirect(XDP_FLAGS_DRV_MODE, 
BPF_F_BROADCAST);
+
+       if (test__start_subtest("DRV_MODE/(BROADCAST | EXCLUDE_INGRESS)"))
+               xdp_veth_broadcast_redirect(XDP_FLAGS_DRV_MODE,
+                                           BPF_F_BROADCAST | 
BPF_F_EXCLUDE_INGRESS);
+
+       if (test__start_subtest("SKB_MODE/BROADCAST"))
+               xdp_veth_broadcast_redirect(XDP_FLAGS_SKB_MODE, 
BPF_F_BROADCAST);
+
+       if (test__start_subtest("SKB_MODE/(BROADCAST | EXCLUDE_INGRESS)"))
+               xdp_veth_broadcast_redirect(XDP_FLAGS_SKB_MODE,
+                                           BPF_F_BROADCAST | 
BPF_F_EXCLUDE_INGRESS);
+}
diff --git a/tools/testing/selftests/bpf/progs/xdp_redirect_map.c 
b/tools/testing/selftests/bpf/progs/xdp_redirect_map.c
index 
682dda8dabbc9abbb5d1b0b22dd5f81124142e79..14385df71d7fc40c3b0ee5c6ea0760d0e7336d71
 100644
--- a/tools/testing/selftests/bpf/progs/xdp_redirect_map.c
+++ b/tools/testing/selftests/bpf/progs/xdp_redirect_map.c
@@ -1,7 +1,11 @@
  // SPDX-License-Identifier: GPL-2.0
+#include <linux/if_ether.h>
+#include <linux/ip.h>

I have compiler error complaining about __always_inline not defined. Likely ordering issue and environment specific. Regardless, I believe the ip.h is unnecessary, so better clean it up.

I am going to land the patch 1-10 and change the cover letter a little to reflect the fact that patch 11-14 will be a followup. Please post the remaining patches after fixing the bpf_map_update_elem issue. Thanks.

+
  #include <linux/bpf.h>
  #include <bpf/bpf_helpers.h>
+#include <bpf/bpf_endian.h>
struct {
        __uint(type, BPF_MAP_TYPE_DEVMAP);
@@ -28,4 +32,49 @@ int xdp_redirect_map_2(struct xdp_md *xdp)
        return bpf_redirect_map(&tx_port, 2, 0);
  }
+struct {
+       __uint(type, BPF_MAP_TYPE_ARRAY);
+       __uint(max_entries, 3);
+       __type(key, __u32);
+       __type(value, __u64);
+} rxcnt SEC(".maps");
+
+static int xdp_count(struct xdp_md *xdp, __u32 key)
+{
+       void *data_end = (void *)(long)xdp->data_end;
+       void *data = (void *)(long)xdp->data;
+       struct ethhdr *eth = data;
+       __u64 *count;
+
+       if (data + sizeof(*eth) > data_end)
+               return XDP_DROP;
+
+       if (bpf_htons(eth->h_proto) == ETH_P_IP) {
+               /* We only count IPv4 packets */
+               count = bpf_map_lookup_elem(&rxcnt, &key);
+               if (count)
+                       *count += 1;
+       }
+
+       return XDP_PASS;
+}
+
+SEC("xdp")
+int xdp_count_0(struct xdp_md *xdp)
+{
+       return xdp_count(xdp, 0);
+}
+
+SEC("xdp")
+int xdp_count_1(struct xdp_md *xdp)
+{
+       return xdp_count(xdp, 1);
+}
+
+SEC("xdp")
+int xdp_count_2(struct xdp_md *xdp)
+{
+       return xdp_count(xdp, 2);
+}
+
  char _license[] SEC("license") = "GPL";



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