netfilter: conntrack: add new sysctl to disable RST check

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: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

diff --git a/Documentation/networking/nf_conntrack-sysctl.rst b/Documentation/networking/nf_conntrack-sysctl.rst
index 0467b30..d31ed6c 100644 (file)
--- a/Documentation/networking/nf_conntrack-sysctl.rst
+++ b/Documentation/networking/nf_conntrack-sysctl.rst
@@ -110,6 +110,12 @@ 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 1, 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 c3094b8..37e5300 100644 (file)
--- a/include/net/netns/conntrack.h
+++ b/include/net/netns/conntrack.h
@@ -27,6 +27,7 @@ struct nf_tcp_net {
        u8 tcp_loose;
        u8 tcp_be_liberal;
        u8 tcp_max_retrans;
+       u8 tcp_ignore_invalid_rst;
 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)
        unsigned int offload_timeout;
        unsigned int offload_pickup;

diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index b8ff676..3259416 100644 (file)
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -1068,7 +1068,8 @@ 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, state, "invalid rst");
@@ -1466,6 +1467,9 @@ void nf_conntrack_tcp_init_net(struct net *net)
         */
        tn->tcp_be_liberal = 0;
 
+       /* If it's non-zero, we turn off RST sequence number check */
+       tn->tcp_ignore_invalid_rst = 0;
+
        /* Max number of the retransmitted packets without receiving an (acceptable)
         * ACK from the destination. If this number is reached, a shorter timer
         * will be started.

diff --git a/net/netfilter/nf_conntrack_standalone.c b/net/netfilter/nf_conntrack_standalone.c
index f57a951..214d9f9 100644 (file)
--- a/net/netfilter/nf_conntrack_standalone.c
+++ b/net/netfilter/nf_conntrack_standalone.c
@@ -579,6 +579,7 @@ enum nf_ct_sysctl_index {
 #endif
        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,
@@ -798,6 +799,14 @@ static struct ctl_table nf_ct_sysctl_table[] = {
                .extra1         = SYSCTL_ZERO,
                .extra2         = SYSCTL_ONE,
        },
+       [NF_SYSCTL_CT_PROTO_TCP_IGNORE_INVALID_RST] = {
+               .procname       = "nf_conntrack_tcp_ignore_invalid_rst",
+               .maxlen         = sizeof(u8),
+               .mode           = 0644,
+               .proc_handler   = proc_dou8vec_minmax,
+               .extra1         = SYSCTL_ZERO,
+               .extra2         = SYSCTL_ONE,
+       },
        [NF_SYSCTL_CT_PROTO_TCP_MAX_RETRANS] = {
                .procname       = "nf_conntrack_tcp_max_retrans",
                .maxlen         = sizeof(u8),
@@ -1004,6 +1013,7 @@ 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
 
 #if IS_ENABLED(CONFIG_NF_FLOW_TABLE)