flow_dissector: introduce programable flow_dissector

Introduce dissector infrastructure which allows user to specify which
parts of skb he wants to dissect.

Signed-off-by: Jiri Pirko <jiri@resnulli.us>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index e4ee761..20239e8 100644 (file)
--- a/include/net/flow_dissector.h
+++ b/include/net/flow_dissector.h
@@ -1,6 +1,64 @@
 #ifndef _NET_FLOW_DISSECTOR_H
 #define _NET_FLOW_DISSECTOR_H
 
+/**
+ * struct flow_dissector_key_basic:
+ * @thoff: Transport header offset
+ * @n_proto: Network header protocol (eg. IPv4/IPv6)
+ * @ip_proto: Transport header protocol (eg. TCP/UDP)
+ */
+struct flow_dissector_key_basic {
+       u16     thoff;
+       __be16  n_proto;
+       u8      ip_proto;
+};
+
+/**
+ * struct flow_dissector_key_addrs:
+ * @src: source ip address in case of IPv4
+ *      For IPv6 it contains 32bit hash of src address
+ * @dst: destination ip address in case of IPv4
+ *      For IPv6 it contains 32bit hash of dst address
+ */
+struct flow_dissector_key_addrs {
+       /* (src,dst) must be grouped, in the same way than in IP header */
+       __be32 src;
+       __be32 dst;
+};
+
+/**
+ * flow_dissector_key_tp_ports:
+ *     @ports: port numbers of Transport header
+ *             port16[0]: src port number
+ *             port16[1]: dst port number
+ */
+struct flow_dissector_key_ports {
+       union {
+               __be32 ports;
+               __be16 port16[2];
+       };
+};
+
+enum flow_dissector_key_id {
+       FLOW_DISSECTOR_KEY_BASIC, /* struct flow_dissector_key_basic */
+       FLOW_DISSECTOR_KEY_IPV4_ADDRS, /* struct flow_dissector_key_addrs */
+       FLOW_DISSECTOR_KEY_IPV6_HASH_ADDRS, /* struct flow_dissector_key_addrs */
+       FLOW_DISSECTOR_KEY_PORTS, /* struct flow_dissector_key_ports */
+
+       FLOW_DISSECTOR_KEY_MAX,
+};
+
+struct flow_dissector_key {
+       enum flow_dissector_key_id key_id;
+       size_t offset; /* offset of struct flow_dissector_key_*
+                         in target the struct */
+};
+
+struct flow_dissector {
+       unsigned int used_keys; /* each bit repesents presence of one key id */
+       unsigned short int offset[FLOW_DISSECTOR_KEY_MAX];
+};
+
 /* struct flow_keys:
  *     @src: source ip address in case of IPv4
  *           For IPv6 it contains 32bit hash of src address
@@ -27,6 +85,9 @@ struct flow_keys {
        u8      ip_proto;
 };
 
+void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
+                            const struct flow_dissector_key *key,
+                            unsigned int key_count);
 bool __skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow,
                        void *data, __be16 proto, int nhoff, int hlen);
 

diff --git a/net/core/flow_dissector.c b/net/core/flow_dissector.c
index d885e28..6883e22 100644 (file)
--- a/net/core/flow_dissector.c
+++ b/net/core/flow_dissector.c
@@ -1,3 +1,4 @@
+#include <linux/kernel.h>
 #include <linux/skbuff.h>
 #include <linux/export.h>
 #include <linux/ip.h>
@@ -15,6 +16,53 @@
 #include <net/flow_dissector.h>
 #include <scsi/fc/fc_fcoe.h>
 
+static bool skb_flow_dissector_uses_key(struct flow_dissector *flow_dissector,
+                                       enum flow_dissector_key_id key_id)
+{
+       return flow_dissector->used_keys & (1 << key_id);
+}
+
+static void skb_flow_dissector_set_key(struct flow_dissector *flow_dissector,
+                                      enum flow_dissector_key_id key_id)
+{
+       flow_dissector->used_keys |= (1 << key_id);
+}
+
+static void *skb_flow_dissector_target(struct flow_dissector *flow_dissector,
+                                      enum flow_dissector_key_id key_id,
+                                      void *target_container)
+{
+       return ((char *) target_container) + flow_dissector->offset[key_id];
+}
+
+void skb_flow_dissector_init(struct flow_dissector *flow_dissector,
+                            const struct flow_dissector_key *key,
+                            unsigned int key_count)
+{
+       unsigned int i;
+
+       memset(flow_dissector, 0, sizeof(*flow_dissector));
+
+       for (i = 0; i < key_count; i++, key++) {
+               /* User should make sure that every key target offset is withing
+                * boundaries of unsigned short.
+                */
+               BUG_ON(key->offset > USHRT_MAX);
+               BUG_ON(skb_flow_dissector_uses_key(flow_dissector,
+                                                  key->key_id));
+
+               skb_flow_dissector_set_key(flow_dissector, key->key_id);
+               flow_dissector->offset[key->key_id] = key->offset;
+       }
+
+       /* Ensure that the dissector always includes basic key. That way
+        * we are able to avoid handling lack of it in fast path.
+        */
+       BUG_ON(!skb_flow_dissector_uses_key(flow_dissector,
+                                           FLOW_DISSECTOR_KEY_BASIC));
+}
+EXPORT_SYMBOL(skb_flow_dissector_init);
+
 /* copy saddr & daddr, possibly using 64bit load/store
  * Equivalent to :     flow->src = iph->saddr;
  *                     flow->dst = iph->daddr;