diff --git a/include/net/mptcp.h b/include/net/mptcp.h index 0bc4ab03f48786..814b5f2e3ed5e3 100644 --- a/include/net/mptcp.h +++ b/include/net/mptcp.h @@ -223,6 +223,8 @@ static inline __be32 mptcp_reset_option(const struct sk_buff *skb) return htonl(0u); } + +void mptcp_active_detect_blackhole(struct sock *sk, bool expired); #else static inline void mptcp_init(void) @@ -307,6 +309,8 @@ static inline struct request_sock *mptcp_subflow_reqsk_alloc(const struct reques } static inline __be32 mptcp_reset_option(const struct sk_buff *skb) { return htonl(0u); } + +static inline void mptcp_active_detect_blackhole(struct sock *sk, bool expired) { } #endif /* CONFIG_MPTCP */ #if IS_ENABLED(CONFIG_MPTCP_IPV6) diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index 86169127e4d1fe..79064580c8c0d5 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -282,6 +282,7 @@ static int tcp_write_timeout(struct sock *sk) expired = retransmits_timed_out(sk, retry_until, READ_ONCE(icsk->icsk_user_timeout)); tcp_fastopen_active_detect_blackhole(sk, expired); + mptcp_active_detect_blackhole(sk, expired); if (BPF_SOCK_OPS_TEST_FLAG(tp, BPF_SOCK_OPS_RTO_CB_FLAG)) tcp_call_bpf_3arg(sk, BPF_SOCK_OPS_RTO_CB, diff --git a/net/mptcp/ctrl.c b/net/mptcp/ctrl.c index 99382c317ebb62..0b23e3c5e8ff44 100644 --- a/net/mptcp/ctrl.c +++ b/net/mptcp/ctrl.c @@ -12,6 +12,7 @@ #include #include "protocol.h" +#include "mib.h" #define MPTCP_SYSCTL_PATH "net/mptcp" @@ -277,6 +278,25 @@ static void mptcp_pernet_del_table(struct mptcp_pernet *pernet) {} #endif /* CONFIG_SYSCTL */ +/* Check the number of retransmissions, and fallback to TCP if needed */ +void mptcp_active_detect_blackhole(struct sock *ssk, bool expired) +{ + struct mptcp_subflow_context *subflow; + u32 timeouts; + + if (!sk_is_mptcp(ssk)) + return; + + timeouts = inet_csk(ssk)->icsk_retransmits; + subflow = mptcp_subflow_ctx(ssk); + + if (subflow->request_mptcp && ssk->sk_state == TCP_SYN_SENT && + (timeouts == 2 || (timeouts < 2 && expired))) { + MPTCP_INC_STATS(sock_net(ssk), MPTCP_MIB_MPCAPABLEACTIVEDROP); + mptcp_subflow_early_fallback(mptcp_sk(subflow->conn), subflow); + } +} + static int __net_init mptcp_net_init(struct net *net) { struct mptcp_pernet *pernet = mptcp_get_pernet(net); diff --git a/net/mptcp/mib.c b/net/mptcp/mib.c index ec0d461cb921e0..d70a3e2bfad624 100644 --- a/net/mptcp/mib.c +++ b/net/mptcp/mib.c @@ -15,6 +15,7 @@ static const struct snmp_mib mptcp_snmp_list[] = { SNMP_MIB_ITEM("MPCapableACKRX", MPTCP_MIB_MPCAPABLEPASSIVEACK), SNMP_MIB_ITEM("MPCapableFallbackACK", MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK), SNMP_MIB_ITEM("MPCapableFallbackSYNACK", MPTCP_MIB_MPCAPABLEACTIVEFALLBACK), + SNMP_MIB_ITEM("MPCapableSYNTXDrop", MPTCP_MIB_MPCAPABLEACTIVEDROP), SNMP_MIB_ITEM("MPFallbackTokenInit", MPTCP_MIB_TOKENFALLBACKINIT), SNMP_MIB_ITEM("MPTCPRetrans", MPTCP_MIB_RETRANSSEGS), SNMP_MIB_ITEM("MPJoinNoTokenFound", MPTCP_MIB_JOINNOTOKEN), diff --git a/net/mptcp/mib.h b/net/mptcp/mib.h index d68136f93dac5d..062775700b6328 100644 --- a/net/mptcp/mib.h +++ b/net/mptcp/mib.h @@ -10,6 +10,7 @@ enum linux_mptcp_mib_field { MPTCP_MIB_MPCAPABLEPASSIVEACK, /* Received third ACK with MP_CAPABLE */ MPTCP_MIB_MPCAPABLEPASSIVEFALLBACK,/* Server-side fallback during 3-way handshake */ MPTCP_MIB_MPCAPABLEACTIVEFALLBACK, /* Client-side fallback during 3-way handshake */ + MPTCP_MIB_MPCAPABLEACTIVEDROP, /* Client-side fallback due to a MPC drop */ MPTCP_MIB_TOKENFALLBACKINIT, /* Could not init/allocate token */ MPTCP_MIB_RETRANSSEGS, /* Segments retransmitted at the MPTCP-level */ MPTCP_MIB_JOINNOTOKEN, /* Received MP_JOIN but the token was not found */