From d65eb54fc9307afd69b94403e092b6ef1913466a Mon Sep 17 00:00:00 2001 From: Felix Fietkau <nbd@nbd.name> Date: Mon, 30 Oct 2017 16:17:54 +0530 Subject: [PATCH] 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(+) diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c index 69f687740..f24b62668 100644 --- a/net/netfilter/nf_conntrack_proto_tcp.c +++ b/net/netfilter/nf_conntrack_proto_tcp.c @@ -33,6 +33,9 @@ #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. */ @@ -513,6 +516,9 @@ static bool tcp_in_window(const struct nf_conn *ct, s32 receiver_offset; bool res, in_recv_win; + if (nf_ct_tcp_no_window_check) + return true; + /* * Get the required data from the packet. */ @@ -1479,6 +1485,13 @@ static struct ctl_table tcp_sysctl_table[] = { .mode = 0644, .proc_handler = proc_dointvec, }, + { + .procname = "nf_conntrack_tcp_no_window_check", + .data = &nf_ct_tcp_no_window_check, + .maxlen = sizeof(unsigned int), + .mode = 0644, + .proc_handler = proc_dointvec, + }, { } }; #endif /* CONFIG_SYSCTL */ -- GitLab