Commit d2c5cca3 authored by Jakub Sitnicki's avatar Jakub Sitnicki Committed by Martin KaFai Lau
Browse files

selftests/bpf: Cover skb metadata access after bpf_skb_change_proto 



Add a test to verify that skb metadata remains accessible after calling
bpf_skb_change_proto(), which modifies packet headroom to accommodate
different IP header sizes.

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-v4-16-5ceb08a9b37b@cloudflare.com
parent 85d454af

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

+5 −0
Original line number Diff line number Diff line
@@ -502,6 +502,11 @@ void test_xdp_context_tuntap(void) 
			    skel->progs.helper_skb_change_head_tail,

			    NULL, /* tc prio 2 */

			    &skel->bss->test_pass);

	if (test__start_subtest("helper_skb_change_proto"))

		test_tuntap(skel->progs.ing_xdp,

			    skel->progs.helper_skb_change_proto,

			    NULL, /* tc prio 2 */

			    &skel->bss->test_pass);



	test_xdp_meta__destroy(skel);

}

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

+25 −0
Original line number Diff line number Diff line
@@ -4,6 +4,7 @@ 
#include <linux/if_ether.h>

#include <linux/pkt_cls.h>



#include <bpf/bpf_endian.h>

#include <bpf/bpf_helpers.h>

#include "bpf_kfuncs.h"
@@ -645,4 +646,28 @@ int helper_skb_change_head_tail(struct __sk_buff *ctx) 
	return TC_ACT_SHOT;

}



SEC("tc")

int helper_skb_change_proto(struct __sk_buff *ctx)

{

	int err;



	err = bpf_skb_change_proto(ctx, bpf_htons(ETH_P_IPV6), 0);

	if (err)

		goto out;



	if (!check_skb_metadata(ctx))

		goto out;



	err = bpf_skb_change_proto(ctx, bpf_htons(ETH_P_IP), 0);

	if (err)

		goto out;



	if (!check_skb_metadata(ctx))

		goto out;



	test_pass = true;

out:

	return TC_ACT_SHOT;

}



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