[PATCH bpf-next v2 15/15] selftests/bpf: Cover skb metadata access after bpf_skb_change_proto
From: Jakub Sitnicki <jakub@cloudflare.com>
Date: 2025-10-19 12:46:12
Also in:
bpf
Subsystem:
bpf [general] (safe dynamic programs and tools), bpf [selftests] (test runners & infrastructure), kernel selftest framework, the rest, xdp (express data path) · Maintainers:
Alexei Starovoitov, Daniel Borkmann, Andrii Nakryiko, Eduard Zingerman, Kumar Kartikeya Dwivedi, Shuah Khan, Shuah Khan, Linus Torvalds, David S. Miller, Jakub Kicinski, Jesper Dangaard Brouer, John Fastabend
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: Jakub Sitnicki <jakub@cloudflare.com> --- .../bpf/prog_tests/xdp_context_test_run.c | 5 +++++ tools/testing/selftests/bpf/progs/test_xdp_meta.c | 25 ++++++++++++++++++++++ 2 files changed, 30 insertions(+)
diff --git a/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c b/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c
index 8880feb84cbf..6272d0451d23 100644
--- a/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c
+++ b/tools/testing/selftests/bpf/prog_tests/xdp_context_test_run.c@@ -506,6 +506,11 @@ 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); }
diff --git a/tools/testing/selftests/bpf/progs/test_xdp_meta.c b/tools/testing/selftests/bpf/progs/test_xdp_meta.c
index 30ad4b1d00d5..6e4abac63e68 100644
--- a/tools/testing/selftests/bpf/progs/test_xdp_meta.c
+++ b/tools/testing/selftests/bpf/progs/test_xdp_meta.c@@ -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";
--
2.43.0