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[79.184.211.13]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-b728968208esm41400266b.52.2025.11.05.12.20.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 05 Nov 2025 12:20:07 -0800 (PST) From: Jakub Sitnicki Date: Wed, 05 Nov 2025 21:19:50 +0100 Subject: [PATCH bpf-next v4 13/16] selftests/bpf: Cover skb metadata access after vlan push/pop helper Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20251105-skb-meta-rx-path-v4-13-5ceb08a9b37b@cloudflare.com> References: <20251105-skb-meta-rx-path-v4-0-5ceb08a9b37b@cloudflare.com> In-Reply-To: <20251105-skb-meta-rx-path-v4-0-5ceb08a9b37b@cloudflare.com> To: bpf@vger.kernel.org Cc: "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Simon Horman , Martin KaFai Lau , Daniel Borkmann , John Fastabend , Stanislav Fomichev , Alexei Starovoitov , Andrii Nakryiko , Eduard Zingerman , Song Liu , Yonghong Song , KP Singh , Hao Luo , Jiri Olsa , Arthur Fabre , Jesper Dangaard Brouer , netdev@vger.kernel.org, kernel-team@cloudflare.com X-Mailer: b4 0.15-dev-07fe9 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: Jakub Sitnicki --- .../bpf/prog_tests/xdp_context_test_run.c | 6 +++ tools/testing/selftests/bpf/progs/test_xdp_meta.c | 43 ++++++++++++++++++++++ 2 files changed, 49 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 a129c3057202..97c8f876f673 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 @@ -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); } diff --git a/tools/testing/selftests/bpf/progs/test_xdp_meta.c b/tools/testing/selftests/bpf/progs/test_xdp_meta.c index a70de55c6997..04c7487bb350 100644 --- a/tools/testing/selftests/bpf/progs/test_xdp_meta.c +++ b/tools/testing/selftests/bpf/progs/test_xdp_meta.c @@ -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"; -- 2.43.0