Commit fbff949e authored by Jiri Pirko's avatar Jiri Pirko Committed by David S. Miller
Browse files

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: default avatarJiri Pirko <jiri@resnulli.us>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 0db89b8b

include/net/flow_dissector.h

+61 −0
Original line number Diff line number Diff line 
#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);

net/core/flow_dissector.c

+48 −0
Original line number Diff line number Diff line 
#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;