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authorJiri Pirko <jiri@resnulli.us>2015-05-12 14:56:15 +0200
committerDavid S. Miller <davem@davemloft.net>2015-05-13 15:19:47 -0400
commitfbff949e3bc7f3f7d9e8b3ef4855ec7138276a25 (patch)
treead9107461ea0fe95a5032d0ff6f9ec18755aaf32
parent0db89b8b3243829704225e756ca7417e06812bba (diff)
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>
-rw-r--r--include/net/flow_dissector.h61
-rw-r--r--net/core/flow_dissector.c48
2 files changed, 109 insertions, 0 deletions
diff --git a/include/net/flow_dissector.h b/include/net/flow_dissector.h
index e4ee761ca8c0..20239e807f77 100644
--- 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 d885e282908e..6883e22b8fc4 100644
--- 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;

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