3.2.65-rc1 review patch. If anyone has any objections, please let me know.
------------------ From: Eric Dumazet <[email protected]> commit bd14b1b2e29bd6812597f896dde06eaf7c6d2f24 upstream. It appears some networks play bad games with the two bits reserved for ECN. This can trigger false congestion notifications and very slow transferts. Since RFC 3168 (6.1.1) forbids SYN packets to carry CT bits, we can disable TCP ECN negociation if it happens we receive mangled CT bits in the SYN packet. Signed-off-by: Eric Dumazet <[email protected]> Cc: Perry Lorier <[email protected]> Cc: Matt Mathis <[email protected]> Cc: Yuchung Cheng <[email protected]> Cc: Neal Cardwell <[email protected]> Cc: Wilmer van der Gaast <[email protected]> Cc: Ankur Jain <[email protected]> Cc: Tom Herbert <[email protected]> Cc: Dave Täht <[email protected]> Acked-by: Neal Cardwell <[email protected]> Signed-off-by: David S. Miller <[email protected]> Signed-off-by: Ben Hutchings <[email protected]> Cc: Florian Westphal <[email protected]> --- include/net/tcp.h | 23 ++++++++++++++++------- net/ipv4/tcp_ipv4.c | 2 +- net/ipv6/tcp_ipv6.c | 2 +- 3 files changed, 18 insertions(+), 9 deletions(-) --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -358,13 +358,6 @@ static inline void tcp_dec_quickack_mode #define TCP_ECN_DEMAND_CWR 4 #define TCP_ECN_SEEN 8 -static __inline__ void -TCP_ECN_create_request(struct request_sock *req, struct tcphdr *th) -{ - if (sysctl_tcp_ecn && th->ece && th->cwr) - inet_rsk(req)->ecn_ok = 1; -} - enum tcp_tw_status { TCP_TW_SUCCESS = 0, TCP_TW_RST = 1, @@ -652,6 +645,22 @@ struct tcp_skb_cb { #define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0])) +/* RFC3168 : 6.1.1 SYN packets must not have ECT/ECN bits set + * + * If we receive a SYN packet with these bits set, it means a network is + * playing bad games with TOS bits. In order to avoid possible false congestion + * notifications, we disable TCP ECN negociation. + */ +static inline void +TCP_ECN_create_request(struct request_sock *req, const struct sk_buff *skb) +{ + const struct tcphdr *th = tcp_hdr(skb); + + if (sysctl_tcp_ecn && th->ece && th->cwr && + INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield)) + inet_rsk(req)->ecn_ok = 1; +} + /* Due to TSO, an SKB can be composed of multiple actual * packets. To keep these tracked properly, we use this. */ --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -1352,7 +1352,7 @@ int tcp_v4_conn_request(struct sock *sk, goto drop_and_free; if (!want_cookie || tmp_opt.tstamp_ok) - TCP_ECN_create_request(req, tcp_hdr(skb)); + TCP_ECN_create_request(req, skb); if (want_cookie) { isn = cookie_v4_init_sequence(sk, skb, &req->mss); --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -1254,7 +1254,7 @@ static int tcp_v6_conn_request(struct so ipv6_addr_copy(&treq->rmt_addr, &ipv6_hdr(skb)->saddr); ipv6_addr_copy(&treq->loc_addr, &ipv6_hdr(skb)->daddr); if (!want_cookie || tmp_opt.tstamp_ok) - TCP_ECN_create_request(req, tcp_hdr(skb)); + TCP_ECN_create_request(req, skb); treq->iif = sk->sk_bound_dev_if; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
