diff options
| -rw-r--r-- | Documentation/networking/ip-sysctl.txt | 8 | ||||
| -rw-r--r-- | include/net/netns/ipv4.h | 1 | ||||
| -rw-r--r-- | net/ipv4/sysctl_net_ipv4.c | 11 | ||||
| -rw-r--r-- | net/ipv4/tcp_ipv4.c | 1 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 3 |
5 files changed, 22 insertions, 2 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index 709d24b4b533..21ad4f3cece8 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -220,6 +220,14 @@ tcp_base_mss - INTEGER Path MTU discovery (MTU probing). If MTU probing is enabled, this is the initial MSS used by the connection. +tcp_min_snd_mss - INTEGER + TCP SYN and SYNACK messages usually advertise an ADVMSS option, + as described in RFC 1122 and RFC 6691. + If this ADVMSS option is smaller than tcp_min_snd_mss, + it is silently capped to tcp_min_snd_mss. + + Default : 48 (at least 8 bytes of payload per segment) + tcp_congestion_control - STRING Set the congestion control algorithm to be used for new connections. The algorithm "reno" is always available, but diff --git a/include/net/netns/ipv4.h b/include/net/netns/ipv4.h index c68926b4899c..61c38f87ea07 100644 --- a/include/net/netns/ipv4.h +++ b/include/net/netns/ipv4.h @@ -88,6 +88,7 @@ struct netns_ipv4 { int sysctl_tcp_fwmark_accept; int sysctl_tcp_mtu_probing; int sysctl_tcp_base_mss; + int sysctl_tcp_min_snd_mss; int sysctl_tcp_probe_threshold; u32 sysctl_tcp_probe_interval; diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index 167ca0fddf9e..6413e36d639d 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -36,6 +36,8 @@ static int ip_local_port_range_min[] = { 1, 1 }; static int ip_local_port_range_max[] = { 65535, 65535 }; static int tcp_adv_win_scale_min = -31; static int tcp_adv_win_scale_max = 31; +static int tcp_min_snd_mss_min = TCP_MIN_SND_MSS; +static int tcp_min_snd_mss_max = 65535; static int ip_ttl_min = 1; static int ip_ttl_max = 255; static int tcp_syn_retries_min = 1; @@ -942,6 +944,15 @@ static struct ctl_table ipv4_net_table[] = { .proc_handler = proc_dointvec, }, { + .procname = "tcp_min_snd_mss", + .data = &init_net.ipv4.sysctl_tcp_min_snd_mss, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = proc_dointvec_minmax, + .extra1 = &tcp_min_snd_mss_min, + .extra2 = &tcp_min_snd_mss_max, + }, + { .procname = "tcp_probe_threshold", .data = &init_net.ipv4.sysctl_tcp_probe_threshold, .maxlen = sizeof(int), diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c index b3d6b8e77300..744afb4fbf84 100644 --- a/net/ipv4/tcp_ipv4.c +++ b/net/ipv4/tcp_ipv4.c @@ -2419,6 +2419,7 @@ static int __net_init tcp_sk_init(struct net *net) net->ipv4.sysctl_tcp_ecn_fallback = 1; net->ipv4.sysctl_tcp_base_mss = TCP_BASE_MSS; + net->ipv4.sysctl_tcp_min_snd_mss = TCP_MIN_SND_MSS; net->ipv4.sysctl_tcp_probe_threshold = TCP_PROBE_THRESHOLD; net->ipv4.sysctl_tcp_probe_interval = TCP_PROBE_INTERVAL; diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index abacd8a12b3e..bed83990847a 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -1332,8 +1332,7 @@ static inline int __tcp_mtu_to_mss(struct sock *sk, int pmtu) mss_now -= icsk->icsk_ext_hdr_len; /* Then reserve room for full set of TCP options and 8 bytes of data */ - if (mss_now < TCP_MIN_SND_MSS) - mss_now = TCP_MIN_SND_MSS; + mss_now = max(mss_now, sock_net(sk)->ipv4.sysctl_tcp_min_snd_mss); return mss_now; } |