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From: Felix Fietkau <nbd@nbd.name>
Subject: netfilter: optional tcp window check
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
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
@@ -31,6 +31,9 @@
#include <net/netfilter/ipv4/nf_conntrack_ipv4.h>
#include <net/netfilter/ipv6/nf_conntrack_ipv6.h>
+/* Do not check the TCP window for incoming packets */
+static int nf_ct_tcp_no_window_check __read_mostly = 1;
+
/* "Be conservative in what you do,
be liberal in what you accept from others."
If it's non-zero, we mark only out of window RST segments as INVALID. */
@@ -476,6 +479,9 @@ static bool tcp_in_window(const struct n
s32 receiver_offset;
bool res, in_recv_win;
+ if (nf_ct_tcp_no_window_check)
+ return true;
+
/*
* Get the required data from the packet.
*/
@@ -1130,7 +1136,7 @@ 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 (!nf_ct_tcp_no_window_check && ct->proto.tcp.last_win == 0 &&
timeouts[new_state] > timeouts[TCP_CONNTRACK_RETRANS])
timeout = timeouts[TCP_CONNTRACK_RETRANS];
else
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -25,6 +25,9 @@
#include <net/netfilter/nf_conntrack_timestamp.h>
#include <linux/rculist_nulls.h>
+/* Do not check the TCP window for incoming packets */
+static int nf_ct_tcp_no_window_check __read_mostly = 1;
+
static bool enable_hooks __read_mostly;
MODULE_PARM_DESC(enable_hooks, "Always enable conntrack hooks");
module_param(enable_hooks, bool, 0000);
@@ -660,6 +663,7 @@ enum nf_ct_sysctl_index {
NF_SYSCTL_CT_PROTO_TIMEOUT_GRE_STREAM,
#endif
+ NF_SYSCTL_CT_PROTO_TCP_NO_WINDOW_CHECK,
__NF_SYSCTL_CT_LAST_SYSCTL,
};
@@ -1014,6 +1018,13 @@ static struct ctl_table nf_ct_sysctl_tab
.proc_handler = proc_dointvec_jiffies,
},
#endif
+ [NF_SYSCTL_CT_PROTO_TCP_NO_WINDOW_CHECK] = {
+ .procname = "nf_conntrack_tcp_no_window_check",
+ .data = &nf_ct_tcp_no_window_check,
+ .maxlen = sizeof(unsigned int),
+ .mode = 0644,
+ .proc_handler = proc_dointvec,
+ },
{}
};
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