Commit 354d020c authored by Jakub Sitnicki's avatar Jakub Sitnicki Committed by Martin KaFai Lau
Browse files

selftests/bpf: Cover skb metadata access after vlan push/pop helper 



Add a test to verify that skb metadata remains accessible after calling
bpf_skb_vlan_push() and bpf_skb_vlan_pop(), which modify the packet
headroom.

Signed-off-by: default avatarJakub Sitnicki <jakub@cloudflare.com>
Signed-off-by: default avatarMartin KaFai Lau <martin.lau@kernel.org>
Link: https://patch.msgid.link/20251105-skb-meta-rx-path-v4-13-5ceb08a9b37b@cloudflare.com
parent 1e1357fd

tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c

+6 −0
Original line number Diff line number Diff line
@@ -478,6 +478,12 @@ void test_xdp_context_tuntap(void) 
		test_tuntap_mirred(skel->progs.ing_xdp,

				   skel->progs.clone_meta_dynptr_rw_before_meta_dynptr_write,

				   &skel->bss->test_pass);

	/* Tests for BPF helpers which touch headroom */

	if (test__start_subtest("helper_skb_vlan_push_pop"))

		test_tuntap(skel->progs.ing_xdp,

			    skel->progs.helper_skb_vlan_push_pop,

			    NULL, /* tc prio 2 */

			    &skel->bss->test_pass);



	test_xdp_meta__destroy(skel);

}

tools/testing/selftests/bpf/progs/test_xdp_meta.c

+43 −0
Original line number Diff line number Diff line
@@ -44,6 +44,16 @@ static bool check_metadata(const char *file, int line, __u8 *meta_have) 


#define check_metadata(meta_have) check_metadata(__FILE__, __LINE__, meta_have)



static bool check_skb_metadata(const char *file, int line, struct __sk_buff *skb)

{

	__u8 *data_meta = ctx_ptr(skb, data_meta);

	__u8 *data = ctx_ptr(skb, data);



	return data_meta + META_SIZE <= data && (check_metadata)(file, line, data_meta);

}



#define check_skb_metadata(skb) check_skb_metadata(__FILE__, __LINE__, skb)



SEC("tc")

int ing_cls(struct __sk_buff *ctx)

{
@@ -525,4 +535,37 @@ int clone_meta_dynptr_rw_before_meta_dynptr_write(struct __sk_buff *ctx) 
	return TC_ACT_SHOT;

}



SEC("tc")

int helper_skb_vlan_push_pop(struct __sk_buff *ctx)

{

	int err;



	/* bpf_skb_vlan_push assumes HW offload for primary VLAN tag. Only

	 * secondary tag push triggers an actual MAC header modification.

	 */

	err = bpf_skb_vlan_push(ctx, 0, 42);

	if (err)

		goto out;

	err = bpf_skb_vlan_push(ctx, 0, 207);

	if (err)

		goto out;



	if (!check_skb_metadata(ctx))

		goto out;



	err = bpf_skb_vlan_pop(ctx);

	if (err)

		goto out;

	err = bpf_skb_vlan_pop(ctx);

	if (err)

		goto out;



	if (!check_skb_metadata(ctx))

		goto out;



	test_pass = true;

out:

	return TC_ACT_SHOT;

}



char _license[] SEC("license") = "GPL";