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Miller" , Jakub Kicinski , Simon Horman , Matthieu Baerts , Mat Martineau , Geliang Tang , Andrii Nakryiko , Eduard Zingerman , Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , Shuah Khan , Florian Westphal , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: Re: [PATCH net v2 3/3] selftests/bpf: Add mptcp test with sockmap In-Reply-To: <20251020060503.325369-4-jiayuan.chen@linux.dev> (Jiayuan Chen's message of "Mon, 20 Oct 2025 14:04:48 +0800") References: <20251020060503.325369-1-jiayuan.chen@linux.dev> <20251020060503.325369-4-jiayuan.chen@linux.dev> Date: Thu, 23 Oct 2025 12:18:42 +0200 Message-ID: <87v7k5vs3h.fsf@cloudflare.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Mon, Oct 20, 2025 at 02:04 PM +08, Jiayuan Chen wrote: > Add test cases to verify that when MPTCP falls back to plain TCP sockets, > they can properly work with sockmap. > > Additionally, add test cases to ensure that sockmap correctly rejects > MPTCP sockets as expected. > > Signed-off-by: Jiayuan Chen > --- > .../testing/selftests/bpf/prog_tests/mptcp.c | 136 ++++++++++++++++++ > .../selftests/bpf/progs/mptcp_sockmap.c | 43 ++++++ > 2 files changed, 179 insertions(+) > create mode 100644 tools/testing/selftests/bpf/progs/mptcp_sockmap.c > > diff --git a/tools/testing/selftests/bpf/prog_tests/mptcp.c b/tools/testing/selftests/bpf/prog_tests/mptcp.c > index f8eb7f9d4fd2..54459b385439 100644 > --- a/tools/testing/selftests/bpf/prog_tests/mptcp.c > +++ b/tools/testing/selftests/bpf/prog_tests/mptcp.c > @@ -6,11 +6,14 @@ > #include > #include > #include > +#include > #include "cgroup_helpers.h" > #include "network_helpers.h" > +#include "socket_helpers.h" > #include "mptcp_sock.skel.h" > #include "mptcpify.skel.h" > #include "mptcp_subflow.skel.h" > +#include "mptcp_sockmap.skel.h" > > #define NS_TEST "mptcp_ns" > #define ADDR_1 "10.0.1.1" > @@ -436,6 +439,137 @@ static void test_subflow(void) > close(cgroup_fd); > } > > +/* Test sockmap on MPTCP server handling non-mp-capable clients. */ > +static void test_sockmap_with_mptcp_fallback(struct mptcp_sockmap *skel) > +{ > + int listen_fd = -1, client_fd1 = -1, client_fd2 = -1; > + int server_fd1 = -1, server_fd2 = -1, sent, recvd; > + char snd[9] = "123456789"; > + char rcv[10]; > + > + listen_fd = start_mptcp_server(AF_INET, NULL, 0, 0); > + if (!ASSERT_OK_FD(listen_fd, "redirect:start_mptcp_server")) > + return; > + > + skel->bss->trace_port = ntohs(get_socket_local_port(listen_fd)); > + skel->bss->sk_index = 0; > + client_fd1 = connect_to_fd_opts(listen_fd, NULL); > + if (!ASSERT_OK_FD(client_fd1, "redirect:connect_to_fd")) > + goto end; > + server_fd1 = xaccept_nonblock(listen_fd, NULL, NULL); > + skel->bss->sk_index = 1; > + client_fd2 = connect_to_fd_opts(listen_fd, NULL); > + if (!ASSERT_OK_FD(client_fd2, "redirect:connect_to_fd")) > + goto end; > + server_fd1 = xaccept_nonblock(listen_fd, NULL, NULL); > + /* test normal redirect behavior: the data sent by client_fd1 can be > + * received by client_fd2 > + */ > + skel->bss->redirect_idx = 1; > + sent = xsend(client_fd1, snd, sizeof(snd), 0); > + if (!ASSERT_EQ(sent, sizeof(snd), "redirect:xsend(client_fd1)")) > + goto end; > + > + /* try to recv more byte to avoid truncation check */ > + recvd = recv_timeout(client_fd2, rcv, sizeof(rcv), MSG_DONTWAIT, 2); > + if (!ASSERT_EQ(recvd, sizeof(snd), "redirect:recv(client_fd2)")) > + goto end; > + > +end: > + if (client_fd1 > 1) > + close(client_fd1); > + if (client_fd2 > 1) > + close(client_fd2); > + if (server_fd1 > 0) > + close(server_fd1); > + if (server_fd2 > 0) > + close(server_fd2); > + close(listen_fd); > +} > + > +static void test_sockmap_reject_mptcp(struct mptcp_sockmap *skel) > +{ > + int listen_fd = -1, server_fd = -1; > + int client_fd1 = -1, client_fd2 = -1; > + int err, zero = 0; > + > + listen_fd = start_mptcp_server(AF_INET, NULL, 0, 0); > + if (!ASSERT_OK_FD(listen_fd, "start_mptcp_server")) > + return; > + > + skel->bss->trace_port = ntohs(get_socket_local_port(listen_fd)); > + skel->bss->sk_index = 0; > + client_fd1 = connect_to_fd(listen_fd, 0); > + if (!ASSERT_OK_FD(client_fd1, "connect_to_fd client_fd1")) > + goto end; > + /* sockmap helper called from sockops prog should reject mptcp sk */ > + if (ASSERT_EQ(skel->bss->helper_ret, -EOPNOTSUPP, "should reject")) > + goto end; I'm confused. Should we bail out (goto end) if EOPNOTSUPP is *not* returned? That is "if (!ASSERT_EQ(...))". > + > + /* skip sockops prog */ > + skel->bss->trace_port = -1; > + client_fd2 = connect_to_fd(listen_fd, 0); > + if (!ASSERT_OK_FD(client_fd2, "connect_to_fd client_fd2")) > + goto end; > + > + server_fd = xaccept_nonblock(listen_fd, NULL, NULL); > + err = bpf_map_update_elem(bpf_map__fd(skel->maps.sock_map), > + &zero, &server_fd, BPF_NOEXIST); > + if (ASSERT_EQ(err, -EOPNOTSUPP, "should reject")) > + goto end; Same here. The check seems backward. > +end: > + if (client_fd1 > 0) > + close(client_fd1); > + if (client_fd2 > 0) > + close(client_fd2); > + if (server_fd > 0) > + close(server_fd); > + close(listen_fd); > +} > + > +static void test_mptcp_sockmap(void) > +{ > + struct mptcp_sockmap *skel; > + struct netns_obj *netns; > + int cgroup_fd, err; > + > + cgroup_fd = test__join_cgroup("/mptcp_sockmap"); > + if (!ASSERT_OK_FD(cgroup_fd, "join_cgroup: mptcp_sockmap")) > + return; > + > + skel = mptcp_sockmap__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "skel_open_load: mptcp_sockmap")) > + goto close_cgroup; > + > + skel->links.mptcp_sockmap_inject = > + bpf_program__attach_cgroup(skel->progs.mptcp_sockmap_inject, cgroup_fd); > + if (!ASSERT_OK_PTR(skel->links.mptcp_sockmap_inject, "attach sockmap")) > + goto skel_destroy; > + > + err = bpf_prog_attach(bpf_program__fd(skel->progs.mptcp_sockmap_redirect), > + bpf_map__fd(skel->maps.sock_map), > + BPF_SK_SKB_STREAM_VERDICT, 0); > + if (!ASSERT_OK(err, "bpf_prog_attach stream verdict")) > + goto skel_destroy; > + > + netns = netns_new(NS_TEST, true); > + if (!ASSERT_OK_PTR(netns, "netns_new: mptcp_sockmap")) > + goto skel_destroy; > + > + if (endpoint_init("subflow") < 0) > + goto close_netns; > + > + test_sockmap_with_mptcp_fallback(skel); > + test_sockmap_reject_mptcp(skel); > + > +close_netns: > + netns_free(netns); > +skel_destroy: > + mptcp_sockmap__destroy(skel); > +close_cgroup: > + close(cgroup_fd); > +} > + > void test_mptcp(void) > { > if (test__start_subtest("base")) > @@ -444,4 +578,6 @@ void test_mptcp(void) > test_mptcpify(); > if (test__start_subtest("subflow")) > test_subflow(); > + if (test__start_subtest("sockmap")) > + test_mptcp_sockmap(); > } > diff --git a/tools/testing/selftests/bpf/progs/mptcp_sockmap.c b/tools/testing/selftests/bpf/progs/mptcp_sockmap.c > new file mode 100644 > index 000000000000..d4eef0cbadb9 > --- /dev/null > +++ b/tools/testing/selftests/bpf/progs/mptcp_sockmap.c > @@ -0,0 +1,43 @@ > +// SPDX-License-Identifier: GPL-2.0 > + > +#include "bpf_tracing_net.h" > + > +char _license[] SEC("license") = "GPL"; > + > +int sk_index; > +int redirect_idx; > +int trace_port; > +int helper_ret; > +struct { > + __uint(type, BPF_MAP_TYPE_SOCKMAP); > + __uint(key_size, sizeof(__u32)); > + __uint(value_size, sizeof(__u32)); > + __uint(max_entries, 100); > +} sock_map SEC(".maps"); > + > +SEC("sockops") > +int mptcp_sockmap_inject(struct bpf_sock_ops *skops) > +{ > + struct bpf_sock *sk; > + > + /* only accept specified connection */ > + if (skops->local_port != trace_port || > + skops->op != BPF_SOCK_OPS_PASSIVE_ESTABLISHED_CB) > + return 1; > + > + sk = skops->sk; > + if (!sk) > + return 1; > + > + /* update sk handler */ > + helper_ret = bpf_sock_map_update(skops, &sock_map, &sk_index, BPF_NOEXIST); > + > + return 1; > +} > + > +SEC("sk_skb/stream_verdict") > +int mptcp_sockmap_redirect(struct __sk_buff *skb) > +{ > + /* redirect skb to the sk under sock_map[redirect_idx] */ > + return bpf_sk_redirect_map(skb, &sock_map, redirect_idx, 0); > +}