diff options
| -rw-r--r-- | net/ipv4/tcp_input.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/net/ipv4/tcp_input.c b/net/ipv4/tcp_input.c index 5dfbc333e79a..6660ce2a7333 100644 --- a/net/ipv4/tcp_input.c +++ b/net/ipv4/tcp_input.c @@ -6263,6 +6263,11 @@ static inline void pr_drop_req(struct request_sock *req, __u16 port, int family) * congestion control: Linux DCTCP asserts ECT on all packets, * including SYN, which is most optimal solution; however, * others, such as FreeBSD do not. + * + * Exception: At least one of the reserved bits of the TCP header (th->res1) is + * set, indicating the use of a future TCP extension (such as AccECN). See + * RFC8311 ยง4.3 which updates RFC3168 to allow the development of such + * extensions. */ static void tcp_ecn_create_request(struct request_sock *req, const struct sk_buff *skb, @@ -6282,7 +6287,7 @@ static void tcp_ecn_create_request(struct request_sock *req, ecn_ok_dst = dst_feature(dst, DST_FEATURE_ECN_MASK); ecn_ok = net->ipv4.sysctl_tcp_ecn || ecn_ok_dst; - if ((!ect && ecn_ok) || tcp_ca_needs_ecn(listen_sk) || + if (((!ect || th->res1) && ecn_ok) || tcp_ca_needs_ecn(listen_sk) || (ecn_ok_dst & DST_FEATURE_ECN_CA) || tcp_bpf_ca_needs_ecn((struct sock *)req)) inet_rsk(req)->ecn_ok = 1; |