* [PATCH bpf-next 2/2] selftests/bpf: Test bpf_skb_check_mtu(BPF_MTU_CHK_SEGS) when transport_header is not set
2025-11-12 23:23 [PATCH bpf-next 1/2] bpf: Check skb->transport_header is set in bpf_skb_check_mtu Martin KaFai Lau
@ 2025-11-12 23:23 ` Martin KaFai Lau
2025-11-15 2:50 ` [PATCH bpf-next 1/2] bpf: Check skb->transport_header is set in bpf_skb_check_mtu patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: Martin KaFai Lau @ 2025-11-12 23:23 UTC (permalink / raw)
To: bpf
Cc: 'Alexei Starovoitov ', 'Andrii Nakryiko ',
'Daniel Borkmann ', netdev
From: Martin KaFai Lau <martin.lau@kernel.org>
Add a test to check that bpf_skb_check_mtu(BPF_MTU_CHK_SEGS) is
rejected (-EINVAL) if skb->transport_header is not set. The test
needs to lower the MTU of the loopback device. Thus, take this
opportunity to run the test in a netns by adding "ns_" to the test
name. The "serial_" prefix can then be removed.
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
---
.../selftests/bpf/prog_tests/check_mtu.c | 23 ++++++++++++++++++-
.../selftests/bpf/progs/test_check_mtu.c | 12 ++++++++++
2 files changed, 34 insertions(+), 1 deletion(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/check_mtu.c b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
index 2a9a30650350..65b4512967e7 100644
--- a/tools/testing/selftests/bpf/prog_tests/check_mtu.c
+++ b/tools/testing/selftests/bpf/prog_tests/check_mtu.c
@@ -153,6 +153,26 @@ static void test_check_mtu_run_tc(struct test_check_mtu *skel,
ASSERT_EQ(mtu_result, mtu_expect, "MTU-compare-user");
}
+static void test_chk_segs_flag(struct test_check_mtu *skel, __u32 mtu)
+{
+ int err, prog_fd = bpf_program__fd(skel->progs.tc_chk_segs_flag);
+ struct __sk_buff skb = {
+ .gso_size = 10,
+ };
+ LIBBPF_OPTS(bpf_test_run_opts, topts,
+ .data_in = &pkt_v4,
+ .data_size_in = sizeof(pkt_v4),
+ .ctx_in = &skb,
+ .ctx_size_in = sizeof(skb),
+ );
+
+ /* Lower the mtu to test the BPF_MTU_CHK_SEGS */
+ SYS_NOFAIL("ip link set dev lo mtu 10");
+ err = bpf_prog_test_run_opts(prog_fd, &topts);
+ SYS_NOFAIL("ip link set dev lo mtu %u", mtu);
+ ASSERT_OK(err, "test_run");
+ ASSERT_EQ(topts.retval, BPF_OK, "retval");
+}
static void test_check_mtu_tc(__u32 mtu, __u32 ifindex)
{
@@ -177,11 +197,12 @@ static void test_check_mtu_tc(__u32 mtu, __u32 ifindex)
test_check_mtu_run_tc(skel, skel->progs.tc_minus_delta, mtu);
test_check_mtu_run_tc(skel, skel->progs.tc_input_len, mtu);
test_check_mtu_run_tc(skel, skel->progs.tc_input_len_exceed, mtu);
+ test_chk_segs_flag(skel, mtu);
cleanup:
test_check_mtu__destroy(skel);
}
-void serial_test_check_mtu(void)
+void test_ns_check_mtu(void)
{
int mtu_lo;
diff --git a/tools/testing/selftests/bpf/progs/test_check_mtu.c b/tools/testing/selftests/bpf/progs/test_check_mtu.c
index 2ec1de11a3ae..7b6b2b342c1d 100644
--- a/tools/testing/selftests/bpf/progs/test_check_mtu.c
+++ b/tools/testing/selftests/bpf/progs/test_check_mtu.c
@@ -7,6 +7,7 @@
#include <stddef.h>
#include <stdint.h>
+#include <errno.h>
char _license[] SEC("license") = "GPL";
@@ -288,3 +289,14 @@ int tc_input_len_exceed(struct __sk_buff *ctx)
global_bpf_mtu_xdp = mtu_len;
return retval;
}
+
+SEC("tc")
+int tc_chk_segs_flag(struct __sk_buff *ctx)
+{
+ __u32 mtu_len = 0;
+ int err;
+
+ err = bpf_check_mtu(ctx, GLOBAL_USER_IFINDEX, &mtu_len, 0, BPF_MTU_CHK_SEGS);
+
+ return err == -EINVAL ? BPF_OK : BPF_DROP;
+}
--
2.47.3
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH bpf-next 1/2] bpf: Check skb->transport_header is set in bpf_skb_check_mtu
2025-11-12 23:23 [PATCH bpf-next 1/2] bpf: Check skb->transport_header is set in bpf_skb_check_mtu Martin KaFai Lau
2025-11-12 23:23 ` [PATCH bpf-next 2/2] selftests/bpf: Test bpf_skb_check_mtu(BPF_MTU_CHK_SEGS) when transport_header is not set Martin KaFai Lau
@ 2025-11-15 2:50 ` patchwork-bot+netdevbpf
1 sibling, 0 replies; 3+ messages in thread
From: patchwork-bot+netdevbpf @ 2025-11-15 2:50 UTC (permalink / raw)
To: Martin KaFai Lau
Cc: bpf, ast, andrii, daniel, netdev, hawk, M202472210, dddddd
Hello:
This series was applied to bpf/bpf-next.git (master)
by Alexei Starovoitov <ast@kernel.org>:
On Wed, 12 Nov 2025 15:23:30 -0800 you wrote:
> From: Martin KaFai Lau <martin.lau@kernel.org>
>
> The bpf_skb_check_mtu helper needs to use skb->transport_header when
> the BPF_MTU_CHK_SEGS flag is used:
>
> bpf_skb_check_mtu(skb, ifindex, &mtu_len, 0, BPF_MTU_CHK_SEGS)
>
> [...]
Here is the summary with links:
- [bpf-next,1/2] bpf: Check skb->transport_header is set in bpf_skb_check_mtu
https://git.kernel.org/bpf/bpf-next/c/d946f3c98328
- [bpf-next,2/2] selftests/bpf: Test bpf_skb_check_mtu(BPF_MTU_CHK_SEGS) when transport_header is not set
https://git.kernel.org/bpf/bpf-next/c/6cc73f35406c
You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html
^ permalink raw reply [flat|nested] 3+ messages in thread