netfilter: nf_conntrack: support conntrack templates

Support initializing selected parameters of new conntrack entries from a
"conntrack template", which is a specially marked conntrack entry attached
to the skb.

Currently the helper and the event delivery masks can be initialized this
way.

Signed-off-by: Patrick McHardy <kaber@trash.net>

3 files changed, 11 insertions, 1 deletions

diff --git a/include/linux/netfilter/nf_conntrack_common.h b/include/linux/netfilter/nf_conntrack_common.h
index ebfed90733f7..c608677dda60 100644
--- a/include/linux/netfilter/nf_conntrack_common.h
+++ b/include/linux/netfilter/nf_conntrack_common.h
@@ -72,6 +72,10 @@ enum ip_conntrack_status {
         /* Connection has fixed timeout. */
         IPS_FIXED_TIMEOUT_BIT = 10,
         IPS_FIXED_TIMEOUT = (1 << IPS_FIXED_TIMEOUT_BIT),
+
+        /* Conntrack is a template */
+        IPS_TEMPLATE_BIT = 11,
+        IPS_TEMPLATE = (1 << IPS_TEMPLATE_BIT),
 };
 
 /* Connection tracking event types */
diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index a0904adfb8f7..5043d61c99a7 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -272,6 +272,11 @@ nf_conntrack_alloc(struct net *net,
                    const struct nf_conntrack_tuple *repl,
                    gfp_t gfp);
 
+static inline int nf_ct_is_template(const struct nf_conn *ct)
+{
+        return test_bit(IPS_TEMPLATE_BIT, &ct->status);
+}
+
 /* It's confirmed if it is, or has been in the hash table. */
 static inline int nf_ct_is_confirmed(struct nf_conn *ct)
 {
diff --git a/include/net/netfilter/nf_conntrack_helper.h b/include/net/netfilter/nf_conntrack_helper.h
index 86be7c4816d6..e17aaa3e19fd 100644
--- a/include/net/netfilter/nf_conntrack_helper.h
+++ b/include/net/netfilter/nf_conntrack_helper.h
@@ -47,7 +47,8 @@ extern void nf_conntrack_helper_unregister(struct nf_conntrack_helper *);
 
 extern struct nf_conn_help *nf_ct_helper_ext_add(struct nf_conn *ct, gfp_t gfp);
 
-extern int __nf_ct_try_assign_helper(struct nf_conn *ct, gfp_t flags);
+extern int __nf_ct_try_assign_helper(struct nf_conn *ct, struct nf_conn *tmpl,
+                                     gfp_t flags);
 
 extern void nf_ct_helper_destroy(struct nf_conn *ct);