[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>

diff --git a/include/linux/netfilter/nf_conntrack_tcp.h b/include/linux/netfilter/nf_conntrack_tcp.h
index 007af4c..22ce299 100644 (file)
--- a/include/linux/netfilter/nf_conntrack_tcp.h
+++ b/include/linux/netfilter/nf_conntrack_tcp.h
@@ -30,6 +30,11 @@ enum tcp_conntrack {
 /* Be liberal in window checking */
 #define IP_CT_TCP_FLAG_BE_LIBERAL              0x08
 
+struct nf_ct_tcp_flags {
+       u_int8_t flags;
+       u_int8_t mask;
+};
+
 #ifdef __KERNEL__
 
 struct ip_ct_tcp_state {

diff --git a/include/linux/netfilter/nfnetlink_conntrack.h b/include/linux/netfilter/nfnetlink_conntrack.h
index b5883cc..d7c3503 100644 (file)
--- a/include/linux/netfilter/nfnetlink_conntrack.h
+++ b/include/linux/netfilter/nfnetlink_conntrack.h
@@ -83,6 +83,10 @@ enum ctattr_protoinfo {
 enum ctattr_protoinfo_tcp {
        CTA_PROTOINFO_TCP_UNSPEC,
        CTA_PROTOINFO_TCP_STATE,
+       CTA_PROTOINFO_TCP_WSCALE_ORIGINAL,
+       CTA_PROTOINFO_TCP_WSCALE_REPLY,
+       CTA_PROTOINFO_TCP_FLAGS_ORIGINAL,
+       CTA_PROTOINFO_TCP_FLAGS_REPLY,
        __CTA_PROTOINFO_TCP_MAX
 };
 #define CTA_PROTOINFO_TCP_MAX (__CTA_PROTOINFO_TCP_MAX - 1)

diff --git a/net/netfilter/nf_conntrack_proto_tcp.c b/net/netfilter/nf_conntrack_proto_tcp.c
index a136362..8439768 100644 (file)
--- 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;