From: Felix Fietkau Subject: netfilter: optional tcp window check Signed-off-by: Felix Fietkau Signed-off-by: Christian 'Ansuel' Marangi --- net/netfilter/nf_conntrack_proto_tcp.c | 13 +++++++++++++ 1 file changed, 13 insertions(+) --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -465,6 +465,9 @@ static bool tcp_in_window(struct nf_conn s32 receiver_offset; bool res, in_recv_win; + if (tn->tcp_no_window_check) + return true; + /* * Get the required data from the packet. */ @@ -1191,7 +1194,7 @@ int nf_conntrack_tcp_packet(struct nf_co IP_CT_TCP_FLAG_DATA_UNACKNOWLEDGED && timeouts[new_state] > timeouts[TCP_CONNTRACK_UNACK]) timeout = timeouts[TCP_CONNTRACK_UNACK]; - else if (ct->proto.tcp.last_win == 0 && + else if (!tn->tcp_no_window_check && ct->proto.tcp.last_win == 0 && timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS]) timeout = timeouts[TCP_CONNTRACK_RETRANS]; else @@ -1507,6 +1510,9 @@ void nf_conntrack_tcp_init_net(struct ne */ tn->tcp_be_liberal = 0; + /* Skip Windows Check */ + tn->tcp_no_window_check = 0; + /* If it's non-zero, we turn off RST sequence number check */ tn->tcp_ignore_invalid_rst = 0; --- a/net/netfilter/nf_conntrack_standalone.c +++ b/net/netfilter/nf_conntrack_standalone.c @@ -633,6 +633,7 @@ enum nf_ct_sysctl_index { #endif NF_SYSCTL_CT_PROTO_TCP_LOOSE, NF_SYSCTL_CT_PROTO_TCP_LIBERAL, + NF_SYSCTL_CT_PROTO_TCP_NO_WINDOW_CHECK, NF_SYSCTL_CT_PROTO_TCP_IGNORE_INVALID_RST, NF_SYSCTL_CT_PROTO_TCP_MAX_RETRANS, NF_SYSCTL_CT_PROTO_TIMEOUT_UDP, @@ -848,6 +849,14 @@ static struct ctl_table nf_ct_sysctl_tab .extra1 = SYSCTL_ZERO, .extra2 = SYSCTL_ONE, }, + [NF_SYSCTL_CT_PROTO_TCP_NO_WINDOW_CHECK] = { + .procname = "nf_conntrack_tcp_no_window_check", + .maxlen = sizeof(u8), + .mode = 0644, + .proc_handler = proc_dou8vec_minmax, + .extra1 = SYSCTL_ZERO, + .extra2 = SYSCTL_ONE, + }, [NF_SYSCTL_CT_PROTO_TCP_IGNORE_INVALID_RST] = { .procname = "nf_conntrack_tcp_ignore_invalid_rst", .maxlen = sizeof(u8), @@ -1058,6 +1067,7 @@ static void nf_conntrack_standalone_init XASSIGN(LOOSE, &tn->tcp_loose); XASSIGN(LIBERAL, &tn->tcp_be_liberal); + XASSIGN(NO_WINDOW_CHECK, &tn->tcp_no_window_check); XASSIGN(MAX_RETRANS, &tn->tcp_max_retrans); XASSIGN(IGNORE_INVALID_RST, &tn->tcp_ignore_invalid_rst); #undef XASSIGN --- a/include/net/netns/conntrack.h +++ b/include/net/netns/conntrack.h @@ -26,6 +26,7 @@ struct nf_tcp_net { unsigned int timeouts[TCP_CONNTRACK_TIMEOUT_MAX]; u8 tcp_loose; u8 tcp_be_liberal; + u8 tcp_no_window_check; u8 tcp_max_retrans; u8 tcp_ignore_invalid_rst; #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)