6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chia-Yu Chang [ Upstream commit 4024081feb87fb11ac7bd36d8c397ccdd81ed302 ] Based on specification: https://tools.ietf.org/id/draft-ietf-tcpm-accurate-ecn-28.txt Based on Section 3.1.5 of AccECN spec (RFC9768), a TCP Server in AccECN mode MUST NOT set ECT on any packet for the rest of the connection, if it has received or sent at least one valid SYN or Acceptable SYN/ACK with (AE,CWR,ECE) = (0,0,0) during the handshake. In addition, a host in AccECN mode that is feeding back the IP-ECN field on a SYN or SYN/ACK MUST feed back the IP-ECN field on the latest valid SYN or acceptable SYN/ACK to arrive. Signed-off-by: Chia-Yu Chang Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/20260131222515.8485-11-chia-yu.chang@nokia-bell-labs.com Signed-off-by: Paolo Abeni Stable-dep-of: c9c90cf437a9 ("mptcp: hold MP_JOIN msk ref when cloning reqsk") Signed-off-by: Sasha Levin --- net/ipv4/inet_connection_sock.c | 3 +++ net/ipv4/tcp_input.c | 2 ++ net/ipv4/tcp_minisocks.c | 36 ++++++++++++++++++++++++--------- net/ipv4/tcp_output.c | 5 ++++- net/ipv4/tcp_timer.c | 3 +++ 5 files changed, 38 insertions(+), 11 deletions(-) diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c index 9a87ea6c63b46..15ad4414cbdb9 100644 --- a/net/ipv4/inet_connection_sock.c +++ b/net/ipv4/inet_connection_sock.c @@ -20,6 +20,7 @@ #include #include #include +#include #include #include @@ -1126,6 +1127,8 @@ static void reqsk_timer_handler(struct timer_list *t) (!resend || !tcp_rtx_synack(sk_listener, req) || inet_rsk(req)->acked)) { + if (req->num_retrans > 1 && tcp_rsk(req)->accecn_ok) + tcp_rsk(req)->accecn_fail_mode |= TCP_ACCECN_ACE_FAIL_SEND; if (req->num_timeout++ == 0) atomic_dec(&queue->young); mod_timer(&req->rsk_timer, jiffies + tcp_reqsk_timeout(req)); diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 6a2c05dff4215..28db1353445bf 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6236,6 +6236,8 @@ static bool tcp_validate_incoming(struct sock *sk, struct sk_buff *skb, if (th->syn) { if (tcp_ecn_mode_accecn(tp)) { accecn_reflector = true; + tp->syn_ect_rcv = TCP_SKB_CB(skb)->ip_dsfield & + INET_ECN_MASK; if (tp->rx_opt.accecn && tp->saw_accecn_opt < TCP_ACCECN_OPT_COUNTER_SEEN) { u8 saw_opt = tcp_accecn_option_init(skb, tp->rx_opt.accecn); diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c index 2d78801866396..ebcd78ad13efa 100644 --- a/net/ipv4/tcp_minisocks.c +++ b/net/ipv4/tcp_minisocks.c @@ -484,6 +484,10 @@ static void tcp_ecn_openreq_child(struct sock *sk, tp->syn_ect_snt = treq->syn_ect_snt; tcp_accecn_third_ack(sk, skb, treq->syn_ect_snt); tp->saw_accecn_opt = treq->saw_accecn_opt; + if (treq->accecn_fail_mode & TCP_ACCECN_ACE_FAIL_SEND) + tcp_accecn_fail_mode_set(tp, TCP_ACCECN_ACE_FAIL_SEND); + if (treq->accecn_fail_mode & TCP_ACCECN_ACE_FAIL_RECV) + tcp_accecn_fail_mode_set(tp, TCP_ACCECN_ACE_FAIL_RECV); tp->prev_ecnfield = treq->syn_ect_rcv; tp->accecn_opt_demand = 1; tcp_ecn_received_counters_payload(sk, skb); @@ -752,16 +756,28 @@ struct sock *tcp_check_req(struct sock *sk, struct sk_buff *skb, */ if (!tcp_oow_rate_limited(sock_net(sk), skb, LINUX_MIB_TCPACKSKIPPEDSYNRECV, - &tcp_rsk(req)->last_oow_ack_time) && - - !tcp_rtx_synack(sk, req)) { - unsigned long expires = jiffies; - - expires += tcp_reqsk_timeout(req); - if (!fastopen) - mod_timer_pending(&req->rsk_timer, expires); - else - req->rsk_timer.expires = expires; + &tcp_rsk(req)->last_oow_ack_time)) { + if (tcp_rsk(req)->accecn_ok) { + u8 ect_rcv = TCP_SKB_CB(skb)->ip_dsfield & + INET_ECN_MASK; + + tcp_rsk(req)->syn_ect_rcv = ect_rcv; + if (tcp_accecn_ace(tcp_hdr(skb)) == 0x0) + tcp_rsk(req)->accecn_fail_mode |= TCP_ACCECN_ACE_FAIL_RECV; + } + if (!tcp_rtx_synack(sk, req)) { + unsigned long expires = jiffies; + + if (req->num_retrans > 1 && tcp_rsk(req)->accecn_ok) + tcp_rsk(req)->accecn_fail_mode |= TCP_ACCECN_ACE_FAIL_SEND; + + expires += tcp_reqsk_timeout(req); + if (!fastopen) + mod_timer_pending(&req->rsk_timer, + expires); + else + req->rsk_timer.expires = expires; + } } return NULL; } diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index ddcc7e53f2e34..f6210d4a3408f 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -333,8 +333,11 @@ static void tcp_ecn_send(struct sock *sk, struct sk_buff *skb, return; if (tcp_ecn_mode_accecn(tp)) { - if (!tcp_accecn_ace_fail_recv(tp)) + if (!tcp_accecn_ace_fail_recv(tp) && + !tcp_accecn_ace_fail_send(tp)) INET_ECN_xmit(sk); + else + INET_ECN_dontxmit(sk); tcp_accecn_set_ace(tp, skb, th); skb_shinfo(skb)->gso_type |= SKB_GSO_TCP_ACCECN; } else { diff --git a/net/ipv4/tcp_timer.c b/net/ipv4/tcp_timer.c index eb549fea8fdd9..017a52022a1a2 100644 --- a/net/ipv4/tcp_timer.c +++ b/net/ipv4/tcp_timer.c @@ -22,6 +22,7 @@ #include #include #include +#include #include static u32 tcp_clamp_rto_to_user_timeout(const struct sock *sk) @@ -482,6 +483,8 @@ static void tcp_fastopen_synack_timer(struct sock *sk, struct request_sock *req) * it's not good to give up too easily. */ tcp_rtx_synack(sk, req); + if (req->num_retrans > 1 && tcp_rsk(req)->accecn_ok) + tcp_rsk(req)->accecn_fail_mode |= TCP_ACCECN_ACE_FAIL_SEND; req->num_timeout++; tcp_update_rto_stats(sk); if (!tp->retrans_stamp) -- 2.53.0