1. Replace IS_ENABLED(CONFIG_BPF) with CONFIG_BPF_SYSCALL for cookie_bpf_ok() and cookie_bpf_check(). CONFIG_BPF is selected by CONFIG_NET unconditionally, so IS_ENABLED(CONFIG_BPF) is always true and provides no real guard. CONFIG_BPF_SYSCALL is the correct config for BPF program functionality. 2. Remove the CONFIG_BPF_SYSCALL guard around struct bpf_tcp_req_attrs. This struct is referenced by bpf_sk_assign_tcp_reqsk() in net/core/filter.c which is compiled unconditionally, so wrapping the definition in a config guard could cause build failures when CONFIG_BPF_SYSCALL=n. 3. Fix mismatched declaration of cookie_bpf_check() between the CONFIG_BPF_SYSCALL and stub paths: the real definition takes 'struct net *net' but the declaration in the header did not. Add the net parameter to the declaration and all call sites. 4. Add missing LINUX_MIB_SYNCOOKIESRECV and LINUX_MIB_SYNCOOKIESFAILED statistics in cookie_bpf_check(), so that BPF custom syncookie validation is accounted for in SNMP counters just like the non-BPF path. Compile-tested with CONFIG_BPF_SYSCALL=y and CONFIG_BPF_SYSCALL not set. Signed-off-by: Jiayuan Chen --- No functional bug here — CONFIG_BPF is always enabled under CONFIG_NET, so the existing code compiles and works correctly. This is a cleanup and improvement, no backport needed. Added a selftest, suggested by Kuniyuki Iwashima. --- include/net/tcp.h | 7 +++---- net/ipv4/syncookies.c | 10 +++++++--- net/ipv6/syncookies.c | 2 +- 3 files changed, 11 insertions(+), 8 deletions(-) diff --git a/include/net/tcp.h b/include/net/tcp.h index 6156d1d068e1..570a8836c2ba 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -598,7 +598,6 @@ struct request_sock *cookie_tcp_reqsk_alloc(const struct request_sock_ops *ops, struct tcp_options_received *tcp_opt, int mss, u32 tsoff); -#if IS_ENABLED(CONFIG_BPF) struct bpf_tcp_req_attrs { u32 rcv_tsval; u32 rcv_tsecr; @@ -612,7 +611,6 @@ struct bpf_tcp_req_attrs { u8 usec_ts_ok; u8 reserved[3]; }; -#endif #ifdef CONFIG_SYN_COOKIES @@ -715,13 +713,14 @@ static inline bool cookie_ecn_ok(const struct net *net, const struct dst_entry * dst_feature(dst, RTAX_FEATURE_ECN); } -#if IS_ENABLED(CONFIG_BPF) +#ifdef CONFIG_BPF_SYSCALL static inline bool cookie_bpf_ok(struct sk_buff *skb) { return skb->sk; } -struct request_sock *cookie_bpf_check(struct sock *sk, struct sk_buff *skb); +struct request_sock *cookie_bpf_check(struct net *net, struct sock *sk, + struct sk_buff *skb); #else static inline bool cookie_bpf_ok(struct sk_buff *skb) { diff --git a/net/ipv4/syncookies.c b/net/ipv4/syncookies.c index f1474598d2c8..d685631438cb 100644 --- a/net/ipv4/syncookies.c +++ b/net/ipv4/syncookies.c @@ -295,8 +295,9 @@ static int cookie_tcp_reqsk_init(struct sock *sk, struct sk_buff *skb, return 0; } -#if IS_ENABLED(CONFIG_BPF) -struct request_sock *cookie_bpf_check(struct sock *sk, struct sk_buff *skb) +#ifdef CONFIG_BPF_SYSCALL +struct request_sock *cookie_bpf_check(struct net *net, struct sock *sk, + struct sk_buff *skb) { struct request_sock *req = inet_reqsk(skb->sk); @@ -306,6 +307,9 @@ struct request_sock *cookie_bpf_check(struct sock *sk, struct sk_buff *skb) if (cookie_tcp_reqsk_init(sk, skb, req)) { reqsk_free(req); req = NULL; + __NET_INC_STATS(net, LINUX_MIB_SYNCOOKIESFAILED); + } else { + __NET_INC_STATS(net, LINUX_MIB_SYNCOOKIESRECV); } return req; @@ -419,7 +423,7 @@ struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb) goto out; if (cookie_bpf_ok(skb)) { - req = cookie_bpf_check(sk, skb); + req = cookie_bpf_check(net, sk, skb); } else { req = cookie_tcp_check(net, sk, skb); if (IS_ERR(req)) diff --git a/net/ipv6/syncookies.c b/net/ipv6/syncookies.c index 4f6f0d751d6c..111d7a41d957 100644 --- a/net/ipv6/syncookies.c +++ b/net/ipv6/syncookies.c @@ -190,7 +190,7 @@ struct sock *cookie_v6_check(struct sock *sk, struct sk_buff *skb) goto out; if (cookie_bpf_ok(skb)) { - req = cookie_bpf_check(sk, skb); + req = cookie_bpf_check(net, sk, skb); } else { req = cookie_tcp_check(net, sk, skb); if (IS_ERR(req)) -- 2.43.0 Add read_tcpext_snmp() helper to network_helpers which reads a TcpExt SNMP counter via nstat, and use it in the tcp_custom_syncookie test to verify that LINUX_MIB_SYNCOOKIESRECV is incremented and LINUX_MIB_SYNCOOKIESFAILED stays unchanged across a successful BPF custom syncookie validation. The delta is captured between start_server() and accept(), which covers the full SYN/ACK/cookie-check path for one connection. Signed-off-by: Jiayuan Chen --- tools/testing/selftests/bpf/network_helpers.c | 22 +++++++++++++++++++ tools/testing/selftests/bpf/network_helpers.h | 1 + .../bpf/prog_tests/tcp_custom_syncookie.c | 20 +++++++++++++++++ 3 files changed, 43 insertions(+) diff --git a/tools/testing/selftests/bpf/network_helpers.c b/tools/testing/selftests/bpf/network_helpers.c index b82f572641b7..3388dd5112b6 100644 --- a/tools/testing/selftests/bpf/network_helpers.c +++ b/tools/testing/selftests/bpf/network_helpers.c @@ -621,6 +621,28 @@ int get_socket_local_port(int sock_fd) return -1; } +int read_tcpext_snmp(const char *name, unsigned long *val) +{ + char cmd[128], buf[128]; + int ret = 0; + FILE *f; + + snprintf(cmd, sizeof(cmd), + "nstat -az TcpExt%s | awk '/TcpExt/ {print $2}'", name); + f = popen(cmd, "r"); + if (!f) + return -errno; + + if (!fgets(buf, sizeof(buf), f)) { + ret = ferror(f) ? -errno : -ENODATA; + goto out; + } + *val = strtoul(buf, NULL, 10); +out: + pclose(f); + return ret; +} + int get_hw_ring_size(char *ifname, struct ethtool_ringparam *ring_param) { struct ifreq ifr = {0}; diff --git a/tools/testing/selftests/bpf/network_helpers.h b/tools/testing/selftests/bpf/network_helpers.h index 79a010c88e11..c53cd781df6e 100644 --- a/tools/testing/selftests/bpf/network_helpers.h +++ b/tools/testing/selftests/bpf/network_helpers.h @@ -84,6 +84,7 @@ int make_sockaddr(int family, const char *addr_str, __u16 port, struct sockaddr_storage *addr, socklen_t *len); char *ping_command(int family); int get_socket_local_port(int sock_fd); +int read_tcpext_snmp(const char *name, unsigned long *val); int get_hw_ring_size(char *ifname, struct ethtool_ringparam *ring_param); int set_hw_ring_size(char *ifname, struct ethtool_ringparam *ring_param); diff --git a/tools/testing/selftests/bpf/prog_tests/tcp_custom_syncookie.c b/tools/testing/selftests/bpf/prog_tests/tcp_custom_syncookie.c index eaf441dc7e79..6adfb4b892f8 100644 --- a/tools/testing/selftests/bpf/prog_tests/tcp_custom_syncookie.c +++ b/tools/testing/selftests/bpf/prog_tests/tcp_custom_syncookie.c @@ -91,12 +91,21 @@ static void transfer_message(int sender, int receiver) static void create_connection(struct test_tcp_custom_syncookie_case *test_case) { + unsigned long recv_before, recv_after; + unsigned long failed_before, failed_after; int server, client, child; server = start_server(test_case->family, test_case->type, test_case->addr, 0, 0); if (!ASSERT_NEQ(server, -1, "start_server")) return; + if (!ASSERT_OK(read_tcpext_snmp("SyncookiesRecv", &recv_before), + "read SyncookiesRecv before")) + goto close_server; + if (!ASSERT_OK(read_tcpext_snmp("SyncookiesFailed", &failed_before), + "read SyncookiesFailed before")) + goto close_server; + client = connect_to_fd(server, 0); if (!ASSERT_NEQ(client, -1, "connect_to_fd")) goto close_server; @@ -105,9 +114,20 @@ static void create_connection(struct test_tcp_custom_syncookie_case *test_case) if (!ASSERT_NEQ(child, -1, "accept")) goto close_client; + if (!ASSERT_OK(read_tcpext_snmp("SyncookiesRecv", &recv_after), + "read SyncookiesRecv after")) + goto close_child; + if (!ASSERT_OK(read_tcpext_snmp("SyncookiesFailed", &failed_after), + "read SyncookiesFailed after")) + goto close_child; + + ASSERT_EQ(recv_after - recv_before, 1, "SyncookiesRecv delta"); + ASSERT_EQ(failed_after - failed_before, 0, "SyncookiesFailed delta"); + transfer_message(client, child); transfer_message(child, client); +close_child: close(child); close_client: close(client); -- 2.43.0