Re: [PATCH bpf-next v2 2/2] selftests/bpf: Add test to cover ktls with bpf_msg_pop_data

On 2025-06-09 10:08:53, Jiayuan Chen wrote:

The selftest can reproduce an issue where using bpf_msg_pop_data() in ktls causes errors on the receiving end.

Signed-off-by: Jiayuan Chen jiayuan.chen@linux.dev

Reviewed-by: John Fastabend john.fastabend@gmail.com

.../selftests/bpf/prog_tests/sockmap_ktls.c | 91 +++++++++++++++++++ .../selftests/bpf/progs/test_sockmap_ktls.c | 4 + 2 files changed, 95 insertions(+)

diff --git a/tools/testing/selftests/bpf/prog_tests/sockmap_ktls.c b/tools/testing/selftests/bpf/prog_tests/sockmap_ktls.c index b6c471da5c28..b87e7f39e15a 100644 --- a/tools/testing/selftests/bpf/prog_tests/sockmap_ktls.c +++ b/tools/testing/selftests/bpf/prog_tests/sockmap_ktls.c @@ -314,6 +314,95 @@ static void test_sockmap_ktls_tx_no_buf(int family, int sotype, bool push) test_sockmap_ktls__destroy(skel); } +static void test_sockmap_ktls_tx_pop(int family, int sotype) +{

• char msg[37] = "0123456789abcdefghijklmnopqrstuvwxyz\0";
• int c = 0, p = 0, one = 1, sent, recvd;
• struct test_sockmap_ktls *skel;
• int prog_fd, map_fd;
• char rcv[50] = {0};
• int err;
• int i, m, r;
• skel = test_sockmap_ktls__open_and_load();
• if (!ASSERT_TRUE(skel, "open ktls skel"))

• return;
  

• err = create_pair(family, sotype, &c, &p);
• if (!ASSERT_OK(err, "create_pair()"))

• goto out;
  

• prog_fd = bpf_program__fd(skel->progs.prog_sk_policy);
• map_fd = bpf_map__fd(skel->maps.sock_map);
• err = bpf_prog_attach(prog_fd, map_fd, BPF_SK_MSG_VERDICT, 0);
• if (!ASSERT_OK(err, "bpf_prog_attach sk msg"))

• goto out;
  

• err = bpf_map_update_elem(map_fd, &one, &c, BPF_NOEXIST);
• if (!ASSERT_OK(err, "bpf_map_update_elem(c)"))

• goto out;
  

• err = init_ktls_pairs(c, p);
• if (!ASSERT_OK(err, "init_ktls_pairs(c, p)"))

• goto out;
  

• struct {

• int	pop_start;
  

• int	pop_len;
  

• } pop_policy[] = {

• /* trim the start */
  

• {0, 2},
  

• {0, 10},
  

• {1, 2},
  

• {1, 10},
  

• /* trim the end */
  

• {35, 2},
  

• /* New entries should be added before this line */
  

• {-1, -1},
  

• };
• i = 0;
• while (pop_policy[i].pop_start >= 0) {

• skel->bss->pop_start = pop_policy[i].pop_start;
  

• skel->bss->pop_end =  pop_policy[i].pop_len;
  

• sent = send(c, msg, sizeof(msg), 0);
  

• if (!ASSERT_EQ(sent, sizeof(msg), "send(msg)"))
  

• 	goto out;
  

Its possible this could actually not send 38B (sent < 38), but then again it is only 38B so I guess it should never fail? Anyways we have this case in a few places already I think and its not tripping CI so lets go for it.

Thanks, John

• recvd = recv_timeout(p, rcv, sizeof(rcv), MSG_DONTWAIT, 1);
  

• if (!ASSERT_EQ(recvd, sizeof(msg) - pop_policy[i].pop_len, "pop len mismatch"))
  

• 	goto out;