diff options
| -rw-r--r-- | Documentation/networking/ip-sysctl.txt | 8 | ||||
| -rw-r--r-- | include/net/tcp.h | 1 | ||||
| -rw-r--r-- | net/ipv4/sysctl_net_ipv4.c | 11 | ||||
| -rw-r--r-- | net/ipv4/tcp_output.c | 4 |
4 files changed, 22 insertions, 2 deletions
diff --git a/Documentation/networking/ip-sysctl.txt b/Documentation/networking/ip-sysctl.txt index 36aa39eee48f..6020d179e56f 100644 --- a/Documentation/networking/ip-sysctl.txt +++ b/Documentation/networking/ip-sysctl.txt @@ -210,6 +210,14 @@ 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/tcp.h b/include/net/tcp.h index 21c68c2c52a8..79762b662de3 100644 --- a/include/net/tcp.h +++ b/include/net/tcp.h @@ -270,6 +270,7 @@ extern int sysctl_tcp_moderate_rcvbuf; extern int sysctl_tcp_tso_win_divisor; extern int sysctl_tcp_mtu_probing; extern int sysctl_tcp_base_mss; +extern int sysctl_tcp_min_snd_mss; extern int sysctl_tcp_workaround_signed_windows; extern int sysctl_tcp_slow_start_after_idle; extern int sysctl_tcp_thin_linear_timeouts; diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c index e1ceafe68cb1..fbbb89c0334a 100644 --- a/net/ipv4/sysctl_net_ipv4.c +++ b/net/ipv4/sysctl_net_ipv4.c @@ -34,6 +34,8 @@ static int tcp_retr1_max = 255; 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_min_snd_mss_min = TCP_MIN_SND_MSS; +static int tcp_min_snd_mss_max = 65535; static int tcp_adv_win_scale_max = 31; static int ip_ttl_min = 1; static int ip_ttl_max = 255; @@ -608,6 +610,15 @@ static struct ctl_table ipv4_table[] = { .proc_handler = proc_dointvec, }, { + .procname = "tcp_min_snd_mss", + .data = &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_workaround_signed_windows", .data = &sysctl_tcp_workaround_signed_windows, .maxlen = sizeof(int), diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c index e760a1ad1956..4a64bebd360d 100644 --- a/net/ipv4/tcp_output.c +++ b/net/ipv4/tcp_output.c @@ -61,6 +61,7 @@ int sysctl_tcp_tso_win_divisor __read_mostly = 3; int sysctl_tcp_mtu_probing __read_mostly = 0; int sysctl_tcp_base_mss __read_mostly = TCP_BASE_MSS; +int sysctl_tcp_min_snd_mss __read_mostly = TCP_MIN_SND_MSS; /* By default, RFC2861 behavior. */ int sysctl_tcp_slow_start_after_idle __read_mostly = 1; @@ -1259,8 +1260,7 @@ 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, sysctl_tcp_min_snd_mss); return mss_now; } |