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-rw-r--r--net/ipv4/tcp_ipv4.c4
-rw-r--r--net/ipv4/tcp_output.c13
2 files changed, 14 insertions, 3 deletions
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 3dfbc21e555..44aef1c1f37 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -1364,6 +1364,10 @@ struct sock *tcp_v4_syn_recv_sock(struct sock *sk, struct sk_buff *skb,
tcp_mtup_init(newsk);
tcp_sync_mss(newsk, dst_mtu(dst));
newtp->advmss = dst_metric(dst, RTAX_ADVMSS);
+ if (tcp_sk(sk)->rx_opt.user_mss &&
+ tcp_sk(sk)->rx_opt.user_mss < newtp->advmss)
+ newtp->advmss = tcp_sk(sk)->rx_opt.user_mss;
+
tcp_initialize_rcv_mss(newsk);
#ifdef CONFIG_TCP_MD5SIG
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 8f9793a37b6..c3d58ee3e16 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2232,6 +2232,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
struct sk_buff *skb;
struct tcp_md5sig_key *md5;
__u8 *md5_hash_location;
+ int mss;
skb = sock_wmalloc(sk, MAX_TCP_HEADER + 15, 1, GFP_ATOMIC);
if (skb == NULL)
@@ -2242,13 +2243,17 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
skb->dst = dst_clone(dst);
+ mss = dst_metric(dst, RTAX_ADVMSS);
+ if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < mss)
+ mss = tp->rx_opt.user_mss;
+
if (req->rcv_wnd == 0) { /* ignored for retransmitted syns */
__u8 rcv_wscale;
/* Set this up on the first call only */
req->window_clamp = tp->window_clamp ? : dst_metric(dst, RTAX_WINDOW);
/* tcp_full_space because it is guaranteed to be the first packet */
tcp_select_initial_window(tcp_full_space(sk),
- dst_metric(dst, RTAX_ADVMSS) - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0),
+ mss - (ireq->tstamp_ok ? TCPOLEN_TSTAMP_ALIGNED : 0),
&req->rcv_wnd,
&req->window_clamp,
ireq->wscale_ok,
@@ -2258,8 +2263,7 @@ struct sk_buff *tcp_make_synack(struct sock *sk, struct dst_entry *dst,
memset(&opts, 0, sizeof(opts));
TCP_SKB_CB(skb)->when = tcp_time_stamp;
- tcp_header_size = tcp_synack_options(sk, req,
- dst_metric(dst, RTAX_ADVMSS),
+ tcp_header_size = tcp_synack_options(sk, req, mss,
skb, &opts, &md5) +
sizeof(struct tcphdr);
@@ -2333,6 +2337,9 @@ static void tcp_connect_init(struct sock *sk)
if (!tp->window_clamp)
tp->window_clamp = dst_metric(dst, RTAX_WINDOW);
tp->advmss = dst_metric(dst, RTAX_ADVMSS);
+ if (tp->rx_opt.user_mss && tp->rx_opt.user_mss < tp->advmss)
+ tp->advmss = tp->rx_opt.user_mss;
+
tcp_initialize_rcv_mss(sk);
tcp_select_initial_window(tcp_full_space(sk),