net/ipv4: VTI support rx-path hook in xfrm4_mode_tunnel.

Incorporated David and Steffen's comments.
Add hook for rx-path xfmr4_mode_tunnel for VTI tunnel module.

Signed-off-by: Saurabh Mohan <saurabh.mohan@vyatta.com>
Reviewed-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 70 insertions, 0 deletions

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 17acbc92476d..d9509eb29b80 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1475,6 +1475,8 @@ extern int xfrm4_output(struct sk_buff *skb);
 extern int xfrm4_output_finish(struct sk_buff *skb);
 extern int xfrm4_tunnel_register(struct xfrm_tunnel *handler, unsigned short family);
 extern int xfrm4_tunnel_deregister(struct xfrm_tunnel *handler, unsigned short family);
+extern int xfrm4_mode_tunnel_input_register(struct xfrm_tunnel *handler);
+extern int xfrm4_mode_tunnel_input_deregister(struct xfrm_tunnel *handler);
 extern int xfrm6_extract_header(struct sk_buff *skb);
 extern int xfrm6_extract_input(struct xfrm_state *x, struct sk_buff *skb);
 extern int xfrm6_rcv_spi(struct sk_buff *skb, int nexthdr, __be32 spi);
diff --git a/net/ipv4/xfrm4_mode_tunnel.c b/net/ipv4/xfrm4_mode_tunnel.c
index ed4bf11ef9f4..ddee0a099a2c 100644
--- a/net/ipv4/xfrm4_mode_tunnel.c
+++ b/net/ipv4/xfrm4_mode_tunnel.c
@@ -15,6 +15,65 @@
 #include <net/ip.h>
 #include <net/xfrm.h>
 
+/* Informational hook. The decap is still done here. */
+static struct xfrm_tunnel __rcu *rcv_notify_handlers __read_mostly;
+static DEFINE_MUTEX(xfrm4_mode_tunnel_input_mutex);
+
+int xfrm4_mode_tunnel_input_register(struct xfrm_tunnel *handler)
+{
+        struct xfrm_tunnel __rcu **pprev;
+        struct xfrm_tunnel *t;
+        int ret = -EEXIST;
+        int priority = handler->priority;
+
+        mutex_lock(&xfrm4_mode_tunnel_input_mutex);
+
+        for (pprev = &rcv_notify_handlers;
+             (t = rcu_dereference_protected(*pprev,
+             lockdep_is_held(&xfrm4_mode_tunnel_input_mutex))) != NULL;
+             pprev = &t->next) {
+                if (t->priority > priority)
+                        break;
+                if (t->priority == priority)
+                        goto err;
+
+        }
+
+        handler->next = *pprev;
+        rcu_assign_pointer(*pprev, handler);
+
+        ret = 0;
+
+err:
+        mutex_unlock(&xfrm4_mode_tunnel_input_mutex);
+        return ret;
+}
+EXPORT_SYMBOL_GPL(xfrm4_mode_tunnel_input_register);
+
+int xfrm4_mode_tunnel_input_deregister(struct xfrm_tunnel *handler)
+{
+        struct xfrm_tunnel __rcu **pprev;
+        struct xfrm_tunnel *t;
+        int ret = -ENOENT;
+
+        mutex_lock(&xfrm4_mode_tunnel_input_mutex);
+        for (pprev = &rcv_notify_handlers;
+             (t = rcu_dereference_protected(*pprev,
+             lockdep_is_held(&xfrm4_mode_tunnel_input_mutex))) != NULL;
+             pprev = &t->next) {
+                if (t == handler) {
+                        *pprev = handler->next;
+                        ret = 0;
+                        break;
+                }
+        }
+        mutex_unlock(&xfrm4_mode_tunnel_input_mutex);
+        synchronize_net();
+
+        return ret;
+}
+EXPORT_SYMBOL_GPL(xfrm4_mode_tunnel_input_deregister);
+
 static inline void ipip_ecn_decapsulate(struct sk_buff *skb)
 {
         struct iphdr *inner_iph = ipip_hdr(skb);
@@ -64,8 +123,14 @@ static int xfrm4_mode_tunnel_output(struct xfrm_state *x, struct sk_buff *skb)
         return 0;
 }
 
+#define for_each_input_rcu(head, handler)       \
+        for (handler = rcu_dereference(head);   \
+             handler != NULL;                   \
+             handler = rcu_dereference(handler->next))
+
 static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
 {
+        struct xfrm_tunnel *handler;
         int err = -EINVAL;
 
         if (XFRM_MODE_SKB_CB(skb)->protocol != IPPROTO_IPIP)
@@ -74,6 +139,9 @@ static int xfrm4_mode_tunnel_input(struct xfrm_state *x, struct sk_buff *skb)
         if (!pskb_may_pull(skb, sizeof(struct iphdr)))
                 goto out;
 
+        for_each_input_rcu(rcv_notify_handlers, handler)
+                handler->handler(skb);
+
         if (skb_cloned(skb) &&
             (err = pskb_expand_head(skb, 0, 0, GFP_ATOMIC)))
                 goto out;