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flow_dissector: introduce programable flow_dissector

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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>
This commit is contained in:
Jiri Pirko 2015-05-12 14:56:15 +02:00 committed by David S. Miller
parent 0db89b8b32
commit fbff949e3b
2 changed files with 109 additions and 0 deletions
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61
include/net/flow_dissector.h
View File

@ -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);

48
net/core/flow_dissector.c
View File

@ -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;