[NETFILTER]: ctnetlink: add support for internal tcp connection tracking flags handling

This patch let userspace programs set the IP_CT_TCP_BE_LIBERAL flag to
force the pickup of established connections.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 44 insertions, 1 deletions

diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index a1363626bccc..8439768f9d1c 100644
--- a/net/netfilter/nf_conntrack_proto_tcp.c
+++ b/net/netfilter/nf_conntrack_proto_tcp.c
@@ -1101,11 +1101,26 @@ static int tcp_to_nfattr(struct sk_buff *skb, struct nfattr *nfa,
                          const struct nf_conn *ct)
 {
         struct nfattr *nest_parms;
+        struct nf_ct_tcp_flags tmp = {};
 
         read_lock_bh(&tcp_lock);
         nest_parms = NFA_NEST(skb, CTA_PROTOINFO_TCP);
         NFA_PUT(skb, CTA_PROTOINFO_TCP_STATE, sizeof(u_int8_t),
                 &ct->proto.tcp.state);
+
+        NFA_PUT(skb, CTA_PROTOINFO_TCP_WSCALE_ORIGINAL, sizeof(u_int8_t),
+                &ct->proto.tcp.seen[0].td_scale);
+
+        NFA_PUT(skb, CTA_PROTOINFO_TCP_WSCALE_REPLY, sizeof(u_int8_t),
+                &ct->proto.tcp.seen[1].td_scale);
+
+        tmp.flags = ct->proto.tcp.seen[0].flags;
+        NFA_PUT(skb, CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
+                sizeof(struct nf_ct_tcp_flags), &tmp);
+
+        tmp.flags = ct->proto.tcp.seen[1].flags;
+        NFA_PUT(skb, CTA_PROTOINFO_TCP_FLAGS_REPLY,
+                sizeof(struct nf_ct_tcp_flags), &tmp);
         read_unlock_bh(&tcp_lock);
 
         NFA_NEST_END(skb, nest_parms);
@@ -1118,7 +1133,11 @@ nfattr_failure:
 }
 
 static const size_t cta_min_tcp[CTA_PROTOINFO_TCP_MAX] = {
-        [CTA_PROTOINFO_TCP_STATE-1]     = sizeof(u_int8_t),
+        [CTA_PROTOINFO_TCP_STATE-1]           = sizeof(u_int8_t),
+        [CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1] = sizeof(u_int8_t),
+        [CTA_PROTOINFO_TCP_WSCALE_REPLY-1]    = sizeof(u_int8_t),
+        [CTA_PROTOINFO_TCP_FLAGS_ORIGINAL-1]  = sizeof(struct nf_ct_tcp_flags),
+        [CTA_PROTOINFO_TCP_FLAGS_REPLY-1]     = sizeof(struct nf_ct_tcp_flags)
 };
 
 static int nfattr_to_tcp(struct nfattr *cda[], struct nf_conn *ct)
@@ -1142,6 +1161,30 @@ static int nfattr_to_tcp(struct nfattr *cda[], struct nf_conn *ct)
         write_lock_bh(&tcp_lock);
         ct->proto.tcp.state =
                 *(u_int8_t *)NFA_DATA(tb[CTA_PROTOINFO_TCP_STATE-1]);
+
+        if (tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL-1]) {
+                struct nf_ct_tcp_flags *attr =
+                        NFA_DATA(tb[CTA_PROTOINFO_TCP_FLAGS_ORIGINAL-1]);
+                ct->proto.tcp.seen[0].flags &= ~attr->mask;
+                ct->proto.tcp.seen[0].flags |= attr->flags & attr->mask;
+        }
+
+        if (tb[CTA_PROTOINFO_TCP_FLAGS_REPLY-1]) {
+                struct nf_ct_tcp_flags *attr =
+                        NFA_DATA(tb[CTA_PROTOINFO_TCP_FLAGS_REPLY-1]);
+                ct->proto.tcp.seen[1].flags &= ~attr->mask;
+                ct->proto.tcp.seen[1].flags |= attr->flags & attr->mask;
+        }
+
+        if (tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1] &&
+            tb[CTA_PROTOINFO_TCP_WSCALE_REPLY-1] &&
+            ct->proto.tcp.seen[0].flags & IP_CT_TCP_FLAG_WINDOW_SCALE &&
+            ct->proto.tcp.seen[1].flags & IP_CT_TCP_FLAG_WINDOW_SCALE) {
+                ct->proto.tcp.seen[0].td_scale = *(u_int8_t *)
+                        NFA_DATA(tb[CTA_PROTOINFO_TCP_WSCALE_ORIGINAL-1]);
+                ct->proto.tcp.seen[1].td_scale = *(u_int8_t *)
+                        NFA_DATA(tb[CTA_PROTOINFO_TCP_WSCALE_REPLY-1]);
+        }
         write_unlock_bh(&tcp_lock);
 
         return 0;