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Tue, 13 Oct 2026 03:39:16 -0700 (PDT) Received: from 8951987238ab.arnhem.chello.nl ([104.28.187.84]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-c31a9ac62a7sm552462166b.63.2026.10.13.03.39.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 13 Oct 2026 03:39:15 -0700 (PDT) From: Willem Ferguson To: netdev@vger.kernel.org Cc: davem@davemloft.net, edumazet@kernel.org, kuba@kernel.org, pabeni@redhat.com, ncardwell@google.com, bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, eddyz87@gmail.com, memxor@gmail.com, linux-doc@vger.kernel.org, corbet@lwn.net, linux-kselftest@vger.kernel.org, shuah@kernel.org, linux-kernel@vger.kernel.org, kernel-team@cloudflare.com Subject: [RFC PATCH net-next 4/4] selftests/bpf: add tcp_ts_id test Date: Tue, 13 Oct 2026 10:39:06 +0000 Message-ID: <20261013103906.2660384-5-wferguson@cloudflare.com> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261013103906.2660384-1-wferguson@cloudflare.com> References: <20261013103906.2660384-1-wferguson@cloudflare.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Exercise BPF_SOCK_OPS_TCP_TS_ID_CB end to end over IPv6 loopback. A cgroup sock_ops program sets BPF_SOCK_OPS_TCP_TS_ID_CB_FLAG on the listener and answers the callback. With tcp_timestamps=1 and tcp_ts_id_bits=4 the test checks that: - the callback runs exactly once, on the SYN, with args[1] equal to the configured width; - the accepted socket reports the identifier and width through TCP_TS_ID; - the connecting socket reports no identifier, as only passive opens are covered; - a reply that does not fit in the width ("decline" subtest) leaves the accepted socket without an identifier. The test skips when tcp_ts_id_bits does not exist and restores both sysctls afterwards. It defines TCP_TS_ID locally when the libc headers do not have it yet. Signed-off-by: Willem Ferguson --- .../selftests/bpf/prog_tests/tcp_ts_id.c | 150 ++++++++++++++++++ .../selftests/bpf/progs/test_tcp_ts_id_kern.c | 32 ++++ 2 files changed, 182 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/tcp_ts_id.c create mode 100644 tools/testing/selftests/bpf/progs/test_tcp_ts_id_kern.c diff --git a/tools/testing/selftests/bpf/prog_tests/tcp_ts_id.c b/tools/testing/selftests/bpf/prog_tests/tcp_ts_id.c new file mode 100644 index 000000000000..25c1f6d8dd43 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/tcp_ts_id.c @@ -0,0 +1,150 @@ +// SPDX-License-Identifier: GPL-2.0 +#include + +#include +#include + +#include "test_tcp_ts_id_kern.skel.h" + +#define LO_ADDR6 "::1" +#define CG_NAME "/tcp-ts-id-test" + +#ifndef TCP_TS_ID +#define TCP_TS_ID 47 +#define TCP_TS_ID_BITS_SHIFT 8 +#endif + +#define TS_ID_BITS_SYSCTL "/proc/sys/net/ipv4/tcp_ts_id_bits" +#define TIMESTAMPS_SYSCTL "/proc/sys/net/ipv4/tcp_timestamps" +#define EXPECTED_TS_ID 7 +#define EXPECTED_TS_ID_BITS 4 +#define EXPECTED_TS_ID_BITS_STR "4" + +static char saved_ts_id_bits[16]; +static char saved_timestamps[16]; + +static int save_sysctl(const char *path, char *buf) +{ + int err = 0; + FILE *f; + + f = fopen(path, "r"); + if (!f) + return -errno; + + if (fscanf(f, "%15s", buf) != 1) + err = -EINVAL; + fclose(f); + + return err; +} + +static void restore_sysctl(const char *path, const char *buf) +{ + if (buf[0]) + write_sysctl(path, buf); +} + +static void run_ts_id_test(int cg_fd, bool decline) +{ + int listen_fd = -1, cli_fd = -1, accept_fd = -1; + struct test_tcp_ts_id_kern *skel; + socklen_t optlen; + int ts_id; + + skel = test_tcp_ts_id_kern__open_and_load(); + if (!ASSERT_OK_PTR(skel, "open_and_load")) + return; + + skel->bss->ts_id_reply = EXPECTED_TS_ID; + skel->bss->ts_id_decline = decline; + + skel->links.tcp_ts_id_sockops = + bpf_program__attach_cgroup(skel->progs.tcp_ts_id_sockops, + cg_fd); + if (!ASSERT_OK_PTR(skel->links.tcp_ts_id_sockops, "attach_cgroup")) + goto out; + + /* The listener has to be created after the attach to get LISTEN_CB. */ + listen_fd = start_server(AF_INET6, SOCK_STREAM, LO_ADDR6, 0, 0); + if (!ASSERT_NEQ(listen_fd, -1, "start_server")) + goto out; + + cli_fd = connect_to_fd(listen_fd, 0); + if (!ASSERT_NEQ(cli_fd, -1, "connect_to_fd")) + goto out; + + accept_fd = accept(listen_fd, NULL, NULL); + if (!ASSERT_NEQ(accept_fd, -1, "accept")) + goto out; + + ASSERT_EQ(skel->bss->ts_id_cb_count, 1, "cb_count"); + ASSERT_EQ(skel->bss->ts_id_cb_syn, 1, "cb_on_syn"); + ASSERT_EQ(skel->bss->ts_id_cb_bits, EXPECTED_TS_ID_BITS, "cb_bits"); + + /* The identifier must reach the child socket created by the SYN. */ + optlen = sizeof(ts_id); + if (ASSERT_OK(getsockopt(accept_fd, IPPROTO_TCP, TCP_TS_ID, &ts_id, + &optlen), "getsockopt(accept_fd, TCP_TS_ID)")) + ASSERT_EQ(ts_id, decline ? 0 : + (EXPECTED_TS_ID_BITS << TCP_TS_ID_BITS_SHIFT) | + EXPECTED_TS_ID, "server_ts_id"); + + /* Identifiers are passive-open only, so the opener must have none. */ + optlen = sizeof(ts_id); + if (ASSERT_OK(getsockopt(cli_fd, IPPROTO_TCP, TCP_TS_ID, &ts_id, + &optlen), "getsockopt(cli_fd, TCP_TS_ID)")) + ASSERT_EQ(ts_id, 0, "client_ts_id"); +out: + if (accept_fd != -1) + close(accept_fd); + if (cli_fd != -1) + close(cli_fd); + if (listen_fd != -1) + close(listen_fd); + test_tcp_ts_id_kern__destroy(skel); +} + +void test_tcp_ts_id(void) +{ + int cg_fd = -1; + int err; + + err = save_sysctl(TS_ID_BITS_SYSCTL, saved_ts_id_bits); + if (err == -ENOENT) { + test__skip(); + return; + } + if (!ASSERT_OK(err, "read " TS_ID_BITS_SYSCTL)) + return; + + if (!ASSERT_OK(save_sysctl(TIMESTAMPS_SYSCTL, saved_timestamps), + "read " TIMESTAMPS_SYSCTL)) + goto out; + + /* The callback only runs when timestamps are negotiated. */ + if (!ASSERT_OK(write_sysctl(TIMESTAMPS_SYSCTL, "1"), + "write " TIMESTAMPS_SYSCTL)) + goto out; + + /* Identifiers are disabled by default, so the test has to opt in. */ + if (!ASSERT_OK(write_sysctl(TS_ID_BITS_SYSCTL, EXPECTED_TS_ID_BITS_STR), + "write " TS_ID_BITS_SYSCTL)) + goto out; + + cg_fd = test__join_cgroup(CG_NAME); + if (!ASSERT_GE(cg_fd, 0, "test__join_cgroup(" CG_NAME ")")) + goto out; + + if (test__start_subtest("assign")) + run_ts_id_test(cg_fd, false); + + /* Only one sockops program may be attached to the cgroup at a time. */ + if (test__start_subtest("decline")) + run_ts_id_test(cg_fd, true); +out: + if (cg_fd != -1) + close(cg_fd); + restore_sysctl(TIMESTAMPS_SYSCTL, saved_timestamps); + restore_sysctl(TS_ID_BITS_SYSCTL, saved_ts_id_bits); +} diff --git a/tools/testing/selftests/bpf/progs/test_tcp_ts_id_kern.c b/tools/testing/selftests/bpf/progs/test_tcp_ts_id_kern.c new file mode 100644 index 000000000000..07e4e56c4fb1 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/test_tcp_ts_id_kern.c @@ -0,0 +1,32 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +__u32 ts_id_cb_count; +__u32 ts_id_cb_syn; +__u32 ts_id_cb_bits; +__u32 ts_id_reply; +__u32 ts_id_decline; /* set by userspace to exercise the decline path */ + +SEC("sockops") +int tcp_ts_id_sockops(struct bpf_sock_ops *skops) +{ + if (skops->op == BPF_SOCK_OPS_TCP_LISTEN_CB) { + bpf_sock_ops_cb_flags_set(skops, + BPF_SOCK_OPS_TCP_TS_ID_CB_FLAG); + return 1; + } + + if (skops->op != BPF_SOCK_OPS_TCP_TS_ID_CB) + return 1; + + ts_id_cb_count++; + ts_id_cb_syn = !!(skops->skb_tcp_flags & (1U << 1)); + ts_id_cb_bits = skops->args[1]; + /* -1 does not fit in Arg2 bits, so the kernel assigns no ID. */ + skops->reply = ts_id_decline ? -1 : ts_id_reply; + + return 1; +} + +char _license[] SEC("license") = "GPL"; -- 2.47.3