From 04553e40a19178f50ff56470bc72313632fb9994 Mon Sep 17 00:00:00 2001

From: Ali Abdallah <aabdallah@suse.de>

Date: Fri, 28 May 2021 12:49:24 +0200

Subject: [PATCH] netfilter: conntrack: add new sysctl to disable RST check

Patch-mainline: Submitted - 2021-05-27 - https://patchwork.ozlabs.org/project/netfilter-devel/patch/20210527071906.s7z72s7wsene5lib@Fryzen495/

References: bsc#1183947 bsc#1185950

This patch adds a new sysctl tcp_ignore_invalid_rst to disable marking

out of segments RSTs as INVALID.

Signed-off-by: Ali Abdallah <aabdallah@suse.de>

Acked-by: Ali Abdallah <aabdallah@suse.de>

---

 Documentation/networking/nf_conntrack-sysctl.txt |  6 ++++++

 include/net/netns/conntrack.h                    |  3 +++

 net/netfilter/nf_conntrack_proto_tcp.c           |  6 +++++-

 net/netfilter/nf_conntrack_standalone.c          | 10 ++++++++++

 4 files changed, 24 insertions(+), 1 deletion(-)

diff --git a/Documentation/networking/nf_conntrack-sysctl.txt b/Documentation/networking/nf_conntrack-sysctl.txt

index f75c2ce6e..4d4925826 100644

--- a/Documentation/networking/nf_conntrack-sysctl.txt

+++ b/Documentation/networking/nf_conntrack-sysctl.txt

@@ -103,6 +103,12 @@ nf_conntrack_tcp_be_liberal - BOOLEAN

 	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.

+nf_conntrack_tcp_ignore_invalid_rst - BOOLEAN

+	- 0 - disabled (default)

+	- 1 - enabled

+

+	If it's non-zero, we don't mark out of window RST segments as INVALID.

+

 nf_conntrack_tcp_loose - BOOLEAN

 	0 - disabled

 	not 0 - enabled (default)

diff --git a/include/net/netns/conntrack.h b/include/net/netns/conntrack.h

index 806454e76..cc8e97940 100644

--- a/include/net/netns/conntrack.h

+++ b/include/net/netns/conntrack.h

@@ -27,6 +27,9 @@ struct nf_tcp_net {

 	int tcp_loose;

 	int tcp_be_liberal;

 	int tcp_max_retrans;

+#ifndef __GENKSYMS__

+	int tcp_ignore_invalid_rst;

+#endif

 };

 enum udp_conntrack {

diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c

index 9d825992c..35ee0fa95 100644

--- a/net/netfilter/nf_conntrack_proto_tcp.c

+++ b/net/netfilter/nf_conntrack_proto_tcp.c

@@ -36,6 +36,8 @@

     If it's non-zero, we mark only out of window RST segments as INVALID. */

 static int nf_ct_tcp_be_liberal __read_mostly = 0;

+static int nf_ct_tcp_ignore_invalid_rst __read_mostly = 0;

+

 /* If it is set to zero, we disable picking up already established

    connections. */

 static int nf_ct_tcp_loose __read_mostly = 1;

@@ -1078,7 +1080,8 @@ int nf_conntrack_tcp_packet(struct nf_conn *ct,

 			if (seq == 0 && !nf_conntrack_tcp_established(ct))

 				break;

-			if (before(seq, ct->proto.tcp.seen[!dir].td_maxack)) {

+			if (before(seq, ct->proto.tcp.seen[!dir].td_maxack) &&

+			    !tn->tcp_ignore_invalid_rst) {

 				/* Invalid RST  */

 				spin_unlock_bh(&ct->lock);

 				nf_ct_l4proto_log_invalid(skb, ct, "invalid rst");

@@ -1452,6 +1455,7 @@ void nf_conntrack_tcp_init_net(struct net *net)

 	tn->tcp_loose = nf_ct_tcp_loose;

 	tn->tcp_be_liberal = nf_ct_tcp_be_liberal;

 	tn->tcp_max_retrans = nf_ct_tcp_max_retrans;

+	tn->tcp_ignore_invalid_rst = nf_ct_tcp_ignore_invalid_rst;

 }

 const struct nf_conntrack_l4proto nf_conntrack_l4proto_tcp =

diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c

index 0006503d2..638e49f57 100644

--- a/net/netfilter/nf_conntrack_standalone.c

+++ b/net/netfilter/nf_conntrack_standalone.c

@@ -565,6 +565,7 @@ enum nf_ct_sysctl_index {

 	NF_SYSCTL_CT_PROTO_TIMEOUT_TCP_UNACK,

 	NF_SYSCTL_CT_PROTO_TCP_LOOSE,

 	NF_SYSCTL_CT_PROTO_TCP_LIBERAL,

+	NF_SYSCTL_CT_PROTO_TCP_IGNORE_INVALID_RST,

 	NF_SYSCTL_CT_PROTO_TCP_MAX_RETRANS,

 	NF_SYSCTL_CT_PROTO_TIMEOUT_UDP,

 	NF_SYSCTL_CT_PROTO_TIMEOUT_UDP_STREAM,

@@ -770,6 +771,14 @@ static struct ctl_table nf_ct_sysctl_table[] = {

 		.extra1 	= &zero,

 		.extra2 	= &one,

 	},

+	[NF_SYSCTL_CT_PROTO_TCP_IGNORE_INVALID_RST] = {

+		.procname	= "nf_conntrack_tcp_ignore_invalid_rst",

+		.maxlen		= sizeof(int),

+		.mode		= 0644,

+		.proc_handler	= proc_dointvec_minmax,

+		.extra1		= &zero,

+		.extra2		= &one,

+	},

 	[NF_SYSCTL_CT_PROTO_TCP_MAX_RETRANS] = {

 		.procname	= "nf_conntrack_tcp_max_retrans",

 		.maxlen		= sizeof(unsigned int),

@@ -962,6 +971,7 @@ static void nf_conntrack_standalone_init_tcp_sysctl(struct net *net,

 	XASSIGN(LOOSE, &tn->tcp_loose);

 	XASSIGN(LIBERAL, &tn->tcp_be_liberal);

 	XASSIGN(MAX_RETRANS, &tn->tcp_max_retrans);

+	XASSIGN(IGNORE_INVALID_RST, &tn->tcp_ignore_invalid_rst);

 #undef XASSIGN

 }

-- 

2.26.2