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tcp: Retain ECT bits for tos reflection

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For DCTCP, we have to retain the ECT bits set by the congestion control
algorithm on the socket when reflecting syn TOS in syn-ack, in order to
make ECN work properly.

Fixes: ac8f1710c1 ("tcp: reflect tos value received in SYN to the socket")
Reported-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: Wei Wang <weiwan@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Wei Wang 2020-12-08 09:55:08 -08:00 committed by David S. Miller
parent a770bf5156
commit 8ef44b6fe4
2 changed files with 10 additions and 4 deletions
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7
net/ipv4/tcp_ipv4.c
View file

@ -984,7 +984,8 @@ static int tcp_v4_send_synack(const struct sock *sk, struct dst_entry *dst,
__tcp_v4_send_check(skb, ireq->ir_loc_addr, ireq->ir_rmt_addr);
tos = sock_net(sk)->ipv4.sysctl_tcp_reflect_tos ?
tcp_rsk(req)->syn_tos & ~INET_ECN_MASK :
(tcp_rsk(req)->syn_tos & ~INET_ECN_MASK) |
(inet_sk(sk)->tos & INET_ECN_MASK) :
inet_sk(sk)->tos;
if (!INET_ECN_is_capable(tos) &&
@ -1541,7 +1542,9 @@ struct sock *tcp_v4_syn_recv_sock(const struct sock *sk, struct sk_buff *skb,
inet_csk(newsk)->icsk_ext_hdr_len = inet_opt->opt.optlen;
newinet->inet_id = prandom_u32();
/* Set ToS of the new socket based upon the value of incoming SYN. */
/* Set ToS of the new socket based upon the value of incoming SYN.
* ECT bits are set later in tcp_init_transfer().
*/
if (sock_net(sk)->ipv4.sysctl_tcp_reflect_tos)
newinet->tos = tcp_rsk(req)->syn_tos & ~INET_ECN_MASK;

7
net/ipv6/tcp_ipv6.c
View file

@ -528,7 +528,8 @@ static int tcp_v6_send_synack(const struct sock *sk, struct dst_entry *dst,
fl6->flowlabel = ip6_flowlabel(ipv6_hdr(ireq->pktopts));
tclass = sock_net(sk)->ipv4.sysctl_tcp_reflect_tos ?
tcp_rsk(req)->syn_tos & ~INET_ECN_MASK :
(tcp_rsk(req)->syn_tos & ~INET_ECN_MASK) |
(np->tclass & INET_ECN_MASK) :
np->tclass;
if (!INET_ECN_is_capable(tclass) &&
@ -1320,7 +1321,9 @@ static struct sock *tcp_v6_syn_recv_sock(const struct sock *sk, struct sk_buff *
if (np->repflow)
newnp->flow_label = ip6_flowlabel(ipv6_hdr(skb));
/* Set ToS of the new socket based upon the value of incoming SYN. */
/* Set ToS of the new socket based upon the value of incoming SYN.
* ECT bits are set later in tcp_init_transfer().
*/
if (sock_net(sk)->ipv4.sysctl_tcp_reflect_tos)
newnp->tclass = tcp_rsk(req)->syn_tos & ~INET_ECN_MASK;