[PATCH bpf v2 1/4] netkit: Fix setting mac address in l2 mode

[PATCH bpf v2 1/4] netkit: Fix setting mac address in l2 mode

[Daniel Borkmann]

When running Cilium connectivity test suite with netkit in L2 mode, we
found that it is expected to be able to specify a custom MAC address for
the devices, in particular, cilium-cni obtains the specified MAC address
by querying the endpoint and sets the MAC address of the interface inside
the Pod. Thus, fix the missing support in netkit for L2 mode.

Fixes: 35dfaad7188c ("netkit, bpf: Add bpf programmable net device")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
---
 drivers/net/netkit.c | 26 +++++++++++++++++++++-----
 1 file changed, 21 insertions(+), 5 deletions(-)

diff --git a/drivers/net/netkit.c b/drivers/net/netkit.c
index a4d2e76a8d58..272894053e2c 100644
--- a/drivers/net/netkit.c
+++ b/drivers/net/netkit.c
@@ -155,6 +155,16 @@ static void netkit_set_multicast(struct net_device *dev)
 	/* Nothing to do, we receive whatever gets pushed to us! */
 }
 
+static int netkit_set_macaddr(struct net_device *dev, void *sa)
+{
+	struct netkit *nk = netkit_priv(dev);
+
+	if (nk->mode != NETKIT_L2)
+		return -EOPNOTSUPP;
+
+	return eth_mac_addr(dev, sa);
+}
+
 static void netkit_set_headroom(struct net_device *dev, int headroom)
 {
 	struct netkit *nk = netkit_priv(dev), *nk2;
@@ -198,6 +208,7 @@ static const struct net_device_ops netkit_netdev_ops = {
 	.ndo_start_xmit		= netkit_xmit,
 	.ndo_set_rx_mode	= netkit_set_multicast,
 	.ndo_set_rx_headroom	= netkit_set_headroom,
+	.ndo_set_mac_address	= netkit_set_macaddr,
 	.ndo_get_iflink		= netkit_get_iflink,
 	.ndo_get_peer_dev	= netkit_peer_dev,
 	.ndo_get_stats64	= netkit_get_stats,
@@ -300,9 +311,11 @@ static int netkit_validate(struct nlattr *tb[], struct nlattr *data[],
 
 	if (!attr)
 		return 0;
-	NL_SET_ERR_MSG_ATTR(extack, attr,
-			    "Setting Ethernet address is not supported");
-	return -EOPNOTSUPP;
+	if (nla_len(attr) != ETH_ALEN)
+		return -EINVAL;
+	if (!is_valid_ether_addr(nla_data(attr)))
+		return -EADDRNOTAVAIL;
+	return 0;
 }
 
 static struct rtnl_link_ops netkit_link_ops;
@@ -365,6 +378,9 @@ static int netkit_new_link(struct net *src_net, struct net_device *dev,
 		strscpy(ifname, "nk%d", IFNAMSIZ);
 		ifname_assign_type = NET_NAME_ENUM;
 	}
+	if (mode != NETKIT_L2 &&
+	    (tb[IFLA_ADDRESS] || tbp[IFLA_ADDRESS]))
+		return -EOPNOTSUPP;
 
 	net = rtnl_link_get_net(src_net, tbp);
 	if (IS_ERR(net))
@@ -379,7 +395,7 @@ static int netkit_new_link(struct net *src_net, struct net_device *dev,
 
 	netif_inherit_tso_max(peer, dev);
 
-	if (mode == NETKIT_L2)
+	if (mode == NETKIT_L2 && !(ifmp && tbp[IFLA_ADDRESS]))
 		eth_hw_addr_random(peer);
 	if (ifmp && dev->ifindex)
 		peer->ifindex = ifmp->ifi_index;
@@ -402,7 +418,7 @@ static int netkit_new_link(struct net *src_net, struct net_device *dev,
 	if (err < 0)
 		goto err_configure_peer;
 
-	if (mode == NETKIT_L2)
+	if (mode == NETKIT_L2 && !tb[IFLA_ADDRESS])
 		eth_hw_addr_random(dev);
 	if (tb[IFLA_IFNAME])
 		nla_strscpy(dev->name, tb[IFLA_IFNAME], IFNAMSIZ);
-- 
2.34.1

[PATCH bpf v2 2/4] netkit: Fix pkt_type override upon netkit pass verdict

[Daniel Borkmann]

When running Cilium connectivity test suite with netkit in L2 mode, we
found that compared to tcx a few tests were failing which pushed traffic
into an L7 proxy sitting in host namespace. The problem in particular is
around the invocation of eth_type_trans() in netkit.

In case of tcx, this is run before the tcx ingress is triggered inside
host namespace and thus if the BPF program uses the bpf_skb_change_type()
helper the newly set type is retained. However, in case of netkit, the
late eth_type_trans() invocation overrides the earlier decision from the
BPF program which eventually leads to the test failure.

Instead of eth_type_trans(), split out the relevant parts, meaning, reset
of mac header and call to eth_skb_pkt_type() before the BPF program is run
in order to have the same behavior as with tcx, and refactor a small helper
called eth_skb_pull_mac() which is run in case it's passed up the stack
where the mac header must be pulled. With this all connectivity tests pass.

Fixes: 35dfaad7188c ("netkit, bpf: Add bpf programmable net device")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
---
 drivers/net/netkit.c        | 4 +++-
 include/linux/etherdevice.h | 8 ++++++++
 net/ethernet/eth.c          | 4 +---
 3 files changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/net/netkit.c b/drivers/net/netkit.c
index 272894053e2c..16789cd446e9 100644
--- a/drivers/net/netkit.c
+++ b/drivers/net/netkit.c
@@ -55,6 +55,7 @@ static void netkit_prep_forward(struct sk_buff *skb, bool xnet)
 	skb_scrub_packet(skb, xnet);
 	skb->priority = 0;
 	nf_skip_egress(skb, true);
+	skb_reset_mac_header(skb);
 }
 
 static struct netkit *netkit_priv(const struct net_device *dev)
@@ -78,6 +79,7 @@ static netdev_tx_t netkit_xmit(struct sk_buff *skb, struct net_device *dev)
 		     skb_orphan_frags(skb, GFP_ATOMIC)))
 		goto drop;
 	netkit_prep_forward(skb, !net_eq(dev_net(dev), dev_net(peer)));
+	eth_skb_pkt_type(skb, peer);
 	skb->dev = peer;
 	entry = rcu_dereference(nk->active);
 	if (entry)
@@ -85,7 +87,7 @@ static netdev_tx_t netkit_xmit(struct sk_buff *skb, struct net_device *dev)
 	switch (ret) {
 	case NETKIT_NEXT:
 	case NETKIT_PASS:
-		skb->protocol = eth_type_trans(skb, skb->dev);
+		eth_skb_pull_mac(skb);
 		skb_postpull_rcsum(skb, eth_hdr(skb), ETH_HLEN);
 		if (likely(__netif_rx(skb) == NET_RX_SUCCESS)) {
 			dev_sw_netstats_tx_add(dev, 1, len);
diff --git a/include/linux/etherdevice.h b/include/linux/etherdevice.h
index 2ad1ffa4ccb9..0ed47d00549b 100644
--- a/include/linux/etherdevice.h
+++ b/include/linux/etherdevice.h
@@ -636,6 +636,14 @@ static inline void eth_skb_pkt_type(struct sk_buff *skb,
 	}
 }
 
+static inline struct ethhdr *eth_skb_pull_mac(struct sk_buff *skb)
+{
+	struct ethhdr *eth = (struct ethhdr *)skb->data;
+
+	skb_pull_inline(skb, ETH_HLEN);
+	return eth;
+}
+
 /**
  * eth_skb_pad - Pad buffer to mininum number of octets for Ethernet frame
  * @skb: Buffer to pad
diff --git a/net/ethernet/eth.c b/net/ethernet/eth.c
index 049c3adeb850..4e3651101b86 100644
--- a/net/ethernet/eth.c
+++ b/net/ethernet/eth.c
@@ -161,9 +161,7 @@ __be16 eth_type_trans(struct sk_buff *skb, struct net_device *dev)
 	skb->dev = dev;
 	skb_reset_mac_header(skb);
 
-	eth = (struct ethhdr *)skb->data;
-	skb_pull_inline(skb, ETH_HLEN);
-
+	eth = eth_skb_pull_mac(skb);
 	eth_skb_pkt_type(skb, dev);
 
 	/*
-- 
2.34.1

[PATCH bpf v2 3/4] selftests/bpf: Add netkit tests for mac address

[Daniel Borkmann]

This adds simple tests around setting MAC addresses in the different
netkit modes.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
 tools/testing/selftests/bpf/prog_tests/tc_netkit.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/tc_netkit.c b/tools/testing/selftests/bpf/prog_tests/tc_netkit.c
index 15ee7b2fc410..18b2e969a456 100644
--- a/tools/testing/selftests/bpf/prog_tests/tc_netkit.c
+++ b/tools/testing/selftests/bpf/prog_tests/tc_netkit.c
@@ -73,6 +73,16 @@ static int create_netkit(int mode, int policy, int peer_policy, int *ifindex,
 			 "up primary");
 	ASSERT_OK(system("ip addr add dev " netkit_name " 10.0.0.1/24"),
 			 "addr primary");
+
+	if (mode == NETKIT_L3) {
+		ASSERT_EQ(system("ip link set dev " netkit_name
+				 " addr ee:ff:bb:cc:aa:dd 2> /dev/null"), 512,
+				 "set hwaddress");
+	} else {
+		ASSERT_OK(system("ip link set dev " netkit_name
+				 " addr ee:ff:bb:cc:aa:dd"),
+				 "set hwaddress");
+	}
 	if (same_netns) {
 		ASSERT_OK(system("ip link set dev " netkit_peer " up"),
 				 "up peer");
-- 
2.34.1

[PATCH bpf v2 4/4] selftests/bpf: Add netkit test for pkt_type

[Daniel Borkmann]

Add a test case to assert that the skb->pkt_type which was set from the BPF
program is retained from the netkit xmit side to the peer's device at tcx
ingress location.

  # ./vmtest.sh -- ./test_progs -t netkit
  [...]
  ./test_progs -t netkit
  [    1.140780] bpf_testmod: loading out-of-tree module taints kernel.
  [    1.141127] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel
  [    1.284601] tsc: Refined TSC clocksource calibration: 3408.006 MHz
  [    1.286672] clocksource: tsc: mask: 0xffffffffffffffff max_cycles: 0x311fd9b189d, max_idle_ns: 440795225691 ns
  [    1.290384] clocksource: Switched to clocksource tsc
  #345     tc_netkit_basic:OK
  #346     tc_netkit_device:OK
  #347     tc_netkit_multi_links:OK
  #348     tc_netkit_multi_opts:OK
  #349     tc_netkit_neigh_links:OK
  #350     tc_netkit_pkt_type:OK
  Summary: 6/0 PASSED, 0 SKIPPED, 0 FAILED

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
---
 .../selftests/bpf/prog_tests/tc_netkit.c      | 84 +++++++++++++++++++
 .../selftests/bpf/progs/test_tc_link.c        | 33 ++++++++
 2 files changed, 117 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/tc_netkit.c b/tools/testing/selftests/bpf/prog_tests/tc_netkit.c
index 18b2e969a456..b9135720024c 100644
--- a/tools/testing/selftests/bpf/prog_tests/tc_netkit.c
+++ b/tools/testing/selftests/bpf/prog_tests/tc_netkit.c
@@ -99,6 +99,16 @@ static int create_netkit(int mode, int policy, int peer_policy, int *ifindex,
 	return err;
 }
 
+static void move_netkit(void)
+{
+	ASSERT_OK(system("ip link set " netkit_peer " netns foo"),
+			 "move peer");
+	ASSERT_OK(system("ip netns exec foo ip link set dev "
+			 netkit_peer " up"), "up peer");
+	ASSERT_OK(system("ip netns exec foo ip addr add dev "
+			 netkit_peer " 10.0.0.2/24"), "addr peer");
+}
+
 static void destroy_netkit(void)
 {
 	ASSERT_OK(system("ip link del dev " netkit_name), "del primary");
@@ -695,3 +705,77 @@ void serial_test_tc_netkit_neigh_links(void)
 	serial_test_tc_netkit_neigh_links_target(NETKIT_L2, BPF_NETKIT_PRIMARY);
 	serial_test_tc_netkit_neigh_links_target(NETKIT_L3, BPF_NETKIT_PRIMARY);
 }
+
+static void serial_test_tc_netkit_pkt_type_mode(int mode)
+{
+	LIBBPF_OPTS(bpf_netkit_opts, optl_nk);
+	LIBBPF_OPTS(bpf_tcx_opts, optl_tcx);
+	int err, ifindex, ifindex2;
+	struct test_tc_link *skel;
+	struct bpf_link *link;
+
+	err = create_netkit(mode, NETKIT_PASS, NETKIT_PASS,
+			    &ifindex, true);
+	if (err)
+		return;
+
+	ifindex2 = if_nametoindex(netkit_peer);
+	ASSERT_NEQ(ifindex, ifindex2, "ifindex_1_2");
+
+	skel = test_tc_link__open();
+	if (!ASSERT_OK_PTR(skel, "skel_open"))
+		goto cleanup;
+
+	ASSERT_EQ(bpf_program__set_expected_attach_type(skel->progs.tc1,
+		  BPF_NETKIT_PRIMARY), 0, "tc1_attach_type");
+	ASSERT_EQ(bpf_program__set_expected_attach_type(skel->progs.tc7,
+		  BPF_TCX_INGRESS), 0, "tc7_attach_type");
+
+	err = test_tc_link__load(skel);
+	if (!ASSERT_OK(err, "skel_load"))
+		goto cleanup;
+
+	assert_mprog_count_ifindex(ifindex,  BPF_NETKIT_PRIMARY, 0);
+	assert_mprog_count_ifindex(ifindex2, BPF_TCX_INGRESS, 0);
+
+	link = bpf_program__attach_netkit(skel->progs.tc1, ifindex, &optl_nk);
+	if (!ASSERT_OK_PTR(link, "link_attach"))
+		goto cleanup;
+
+	skel->links.tc1 = link;
+
+	assert_mprog_count_ifindex(ifindex,  BPF_NETKIT_PRIMARY, 1);
+	assert_mprog_count_ifindex(ifindex2, BPF_TCX_INGRESS, 0);
+
+	link = bpf_program__attach_tcx(skel->progs.tc7, ifindex2, &optl_tcx);
+	if (!ASSERT_OK_PTR(link, "link_attach"))
+		goto cleanup;
+
+	skel->links.tc7 = link;
+
+	assert_mprog_count_ifindex(ifindex,  BPF_NETKIT_PRIMARY, 1);
+	assert_mprog_count_ifindex(ifindex2, BPF_TCX_INGRESS, 1);
+
+	move_netkit();
+
+	tc_skel_reset_all_seen(skel);
+	skel->bss->set_type = true;
+	ASSERT_EQ(send_icmp(), 0, "icmp_pkt");
+
+	ASSERT_EQ(skel->bss->seen_tc1, true, "seen_tc1");
+	ASSERT_EQ(skel->bss->seen_tc7, true, "seen_tc7");
+
+	ASSERT_EQ(skel->bss->seen_host,  true, "seen_host");
+	ASSERT_EQ(skel->bss->seen_mcast, true, "seen_mcast");
+cleanup:
+	test_tc_link__destroy(skel);
+
+	assert_mprog_count_ifindex(ifindex,  BPF_NETKIT_PRIMARY, 0);
+	destroy_netkit();
+}
+
+void serial_test_tc_netkit_pkt_type(void)
+{
+	serial_test_tc_netkit_pkt_type_mode(NETKIT_L2);
+	serial_test_tc_netkit_pkt_type_mode(NETKIT_L3);
+}
diff --git a/tools/testing/selftests/bpf/progs/test_tc_link.c b/tools/testing/selftests/bpf/progs/test_tc_link.c
index 992400acb957..b64fcb70ef2f 100644
--- a/tools/testing/selftests/bpf/progs/test_tc_link.c
+++ b/tools/testing/selftests/bpf/progs/test_tc_link.c
@@ -4,6 +4,7 @@
 
 #include <linux/bpf.h>
 #include <linux/if_ether.h>
+#include <linux/if_packet.h>
 
 #include <bpf/bpf_endian.h>
 #include <bpf/bpf_helpers.h>
@@ -16,7 +17,13 @@ bool seen_tc3;
 bool seen_tc4;
 bool seen_tc5;
 bool seen_tc6;
+bool seen_tc7;
+
+bool set_type;
+
 bool seen_eth;
+bool seen_host;
+bool seen_mcast;
 
 SEC("tc/ingress")
 int tc1(struct __sk_buff *skb)
@@ -28,8 +35,16 @@ int tc1(struct __sk_buff *skb)
 	if (bpf_skb_load_bytes(skb, 0, &eth, sizeof(eth)))
 		goto out;
 	seen_eth = eth.h_proto == bpf_htons(ETH_P_IP);
+	seen_host = skb->pkt_type == PACKET_HOST;
+	if (seen_host && set_type) {
+		eth.h_dest[0] = 4;
+		if (bpf_skb_store_bytes(skb, 0, &eth, sizeof(eth), 0))
+			goto fail;
+		bpf_skb_change_type(skb, PACKET_MULTICAST);
+	}
 out:
 	seen_tc1 = true;
+fail:
 	return TCX_NEXT;
 }
 
@@ -67,3 +82,21 @@ int tc6(struct __sk_buff *skb)
 	seen_tc6 = true;
 	return TCX_PASS;
 }
+
+SEC("tc/ingress")
+int tc7(struct __sk_buff *skb)
+{
+	struct ethhdr eth = {};
+
+	if (skb->protocol != __bpf_constant_htons(ETH_P_IP))
+		goto out;
+	if (bpf_skb_load_bytes(skb, 0, &eth, sizeof(eth)))
+		goto out;
+	if (eth.h_dest[0] == 4 && set_type) {
+		seen_mcast = skb->pkt_type == PACKET_MULTICAST;
+		bpf_skb_change_type(skb, PACKET_HOST);
+	}
+out:
+	seen_tc7 = true;
+	return TCX_PASS;
+}
-- 
2.34.1

Re: [PATCH bpf v2 1/4] netkit: Fix setting mac address in l2 mode

[Stanislav Fomichev]

On 05/24, Daniel Borkmann wrote:
> When running Cilium connectivity test suite with netkit in L2 mode, we
> found that it is expected to be able to specify a custom MAC address for
> the devices, in particular, cilium-cni obtains the specified MAC address
> by querying the endpoint and sets the MAC address of the interface inside
> the Pod. Thus, fix the missing support in netkit for L2 mode.
> 
> Fixes: 35dfaad7188c ("netkit, bpf: Add bpf programmable net device")
> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
> Acked-by: Nikolay Aleksandrov <razor@blackwall.org>

For the series:

Acked-by: Stanislav Fomichev <sdf@google.com>

Re: [PATCH bpf v2 4/4] selftests/bpf: Add netkit test for pkt_type

[Martin KaFai Lau]

On 5/24/24 9:36 AM, Daniel Borkmann wrote:
> diff --git a/tools/testing/selftests/bpf/progs/test_tc_link.c b/tools/testing/selftests/bpf/progs/test_tc_link.c
> index 992400acb957..b64fcb70ef2f 100644
> --- a/tools/testing/selftests/bpf/progs/test_tc_link.c
> +++ b/tools/testing/selftests/bpf/progs/test_tc_link.c
> @@ -4,6 +4,7 @@
>   
>   #include <linux/bpf.h>
>   #include <linux/if_ether.h>
> +#include <linux/if_packet.h>

The set looks good.

A minor thing is that I am hitting this compilation issue in my environment:

In file included from progs/test_tc_link.c:7:
In file included from /usr/include/linux/if_packet.h:5:
In file included from /usr/include/asm/byteorder.h:5:
In file included from /usr/include/linux/byteorder/little_endian.h:13:
/usr/include/linux/swab.h:136:8: error: unknown type name '__always_inline'
   136 | static __always_inline unsigned long __swab(const unsigned long y)
       |        ^

Adding '#include <linux/stddef.h>' solved it. If the addition is fine, this can 
be adjusted before landing.

Re: [PATCH bpf v2 4/4] selftests/bpf: Add netkit test for pkt_type

[Alexei Starovoitov]

On Fri, May 24, 2024 at 3:05 PM Martin KaFai Lau <martin.lau@linux.dev> wrote:
>
> On 5/24/24 9:36 AM, Daniel Borkmann wrote:
> > diff --git a/tools/testing/selftests/bpf/progs/test_tc_link.c b/tools/testing/selftests/bpf/progs/test_tc_link.c
> > index 992400acb957..b64fcb70ef2f 100644
> > --- a/tools/testing/selftests/bpf/progs/test_tc_link.c
> > +++ b/tools/testing/selftests/bpf/progs/test_tc_link.c
> > @@ -4,6 +4,7 @@
> >
> >   #include <linux/bpf.h>
> >   #include <linux/if_ether.h>
> > +#include <linux/if_packet.h>
>
> The set looks good.
>
> A minor thing is that I am hitting this compilation issue in my environment:
>
> In file included from progs/test_tc_link.c:7:
> In file included from /usr/include/linux/if_packet.h:5:
> In file included from /usr/include/asm/byteorder.h:5:
> In file included from /usr/include/linux/byteorder/little_endian.h:13:
> /usr/include/linux/swab.h:136:8: error: unknown type name '__always_inline'
>    136 | static __always_inline unsigned long __swab(const unsigned long y)
>        |        ^
>
> Adding '#include <linux/stddef.h>' solved it. If the addition is fine, this can
> be adjusted before landing.

I hit the same build issue. So added stddef.h before if_packet.h as
Martin suggested before applying.

Re: [PATCH bpf v2 1/4] netkit: Fix setting mac address in l2 mode

[patchwork-bot+netdevbpf]

Hello:

This series was applied to bpf/bpf.git (master)
by Alexei Starovoitov <ast@kernel.org>:

On Fri, 24 May 2024 18:36:16 +0200 you wrote:
> When running Cilium connectivity test suite with netkit in L2 mode, we
> found that it is expected to be able to specify a custom MAC address for
> the devices, in particular, cilium-cni obtains the specified MAC address
> by querying the endpoint and sets the MAC address of the interface inside
> the Pod. Thus, fix the missing support in netkit for L2 mode.
> 
> Fixes: 35dfaad7188c ("netkit, bpf: Add bpf programmable net device")
> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
> Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
> 
> [...]

Here is the summary with links:
  - [bpf,v2,1/4] netkit: Fix setting mac address in l2 mode
    https://git.kernel.org/bpf/bpf/c/d6fe532b7499
  - [bpf,v2,2/4] netkit: Fix pkt_type override upon netkit pass verdict
    https://git.kernel.org/bpf/bpf/c/3998d184267d
  - [bpf,v2,3/4] selftests/bpf: Add netkit tests for mac address
    https://git.kernel.org/bpf/bpf/c/998ffeb2738e
  - [bpf,v2,4/4] selftests/bpf: Add netkit test for pkt_type
    https://git.kernel.org/bpf/bpf/c/95348e463eab

You are awesome, thank you!
-- 
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

Re: [PATCH bpf v2 4/4] selftests/bpf: Add netkit test for pkt_type

[Daniel Borkmann]

On 5/25/24 7:55 PM, Alexei Starovoitov wrote:
> On Fri, May 24, 2024 at 3:05 PM Martin KaFai Lau <martin.lau@linux.dev> wrote:
>>
>> On 5/24/24 9:36 AM, Daniel Borkmann wrote:
>>> diff --git a/tools/testing/selftests/bpf/progs/test_tc_link.c b/tools/testing/selftests/bpf/progs/test_tc_link.c
>>> index 992400acb957..b64fcb70ef2f 100644
>>> --- a/tools/testing/selftests/bpf/progs/test_tc_link.c
>>> +++ b/tools/testing/selftests/bpf/progs/test_tc_link.c
>>> @@ -4,6 +4,7 @@
>>>
>>>    #include <linux/bpf.h>
>>>    #include <linux/if_ether.h>
>>> +#include <linux/if_packet.h>
>>
>> The set looks good.
>>
>> A minor thing is that I am hitting this compilation issue in my environment:
>>
>> In file included from progs/test_tc_link.c:7:
>> In file included from /usr/include/linux/if_packet.h:5:
>> In file included from /usr/include/asm/byteorder.h:5:
>> In file included from /usr/include/linux/byteorder/little_endian.h:13:
>> /usr/include/linux/swab.h:136:8: error: unknown type name '__always_inline'
>>     136 | static __always_inline unsigned long __swab(const unsigned long y)
>>         |        ^
>>
>> Adding '#include <linux/stddef.h>' solved it. If the addition is fine, this can
>> be adjusted before landing.
> 
> I hit the same build issue. So added stddef.h before if_packet.h as
> Martin suggested before applying.

Awesome, thanks all!