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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>
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‎include/net/flow_dissector.h

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

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

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