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From 5433bb138a6a3499b05cb8722c8365cf56047aa1 Mon Sep 17 00:00:00 2001
From: Felix Fietkau <nbd@nbd.name>
Date: Tue, 27 Sep 2022 16:22:06 +0200
Subject: [PATCH 63/96] netfilter: optional tcp window check
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Signed-off-by: Christian 'Ansuel' Marangi <ansuelsmth@gmail.com>
---
include/net/netns/conntrack.h | 1 +
net/netfilter/nf_conntrack_proto_tcp.c | 8 +++++++-
net/netfilter/nf_conntrack_standalone.c | 10 ++++++++++
3 files changed, 18 insertions(+), 1 deletion(-)
diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h
index c396a3862e80..82598d767cc3 100644
--- 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)
diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index a634c72b1ffc..8bbc8010170d 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -490,6 +490,9 @@ static bool tcp_in_window(struct nf_conn *ct,
s32 receiver_offset;
bool res, in_recv_win;
+ if (tn->tcp_no_window_check)
+ return true;
+
/*
* Get the required data from the packet.
*/
@@ -1161,7 +1164,7 @@ int nf_conntrack_tcp_packet(struct nf_conn *ct,
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
@@ -1477,6 +1480,9 @@ void nf_conntrack_tcp_init_net(struct net *net)
*/
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;
diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index 8d3be4cc340e..73a1b6c1737e 100644
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -636,6 +636,7 @@ 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,
@@ -852,6 +853,14 @@ static struct ctl_table nf_ct_sysctl_table[] = {
.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),
@@ -1068,6 +1077,7 @@ static void nf_conntrack_standalone_init_tcp_sysctl(struct net *net,
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
--
2.37.2
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