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/*
* Copyright (c) 2007-2013 Nicira, Inc.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
*
* This code is derived from kernel flow_dissector.c
*/
#include <linux/version.h>
#if LINUX_VERSION_CODE < KERNEL_VERSION(2,6,37)
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/if_vlan.h>
#include <net/ip.h>
#include <net/ipv6.h>
#include <linux/igmp.h>
#include <linux/icmp.h>
#include <linux/sctp.h>
#include <linux/dccp.h>
#include <linux/if_tunnel.h>
#include <linux/if_pppox.h>
#include <linux/ppp_defs.h>
#include <net/flow_keys.h>
/* copy saddr & daddr, possibly using 64bit load/store
* Equivalent to : flow->src = iph->saddr;
* flow->dst = iph->daddr;
*/
static void iph_to_flow_copy_addrs(struct flow_keys *flow, const struct iphdr *iph)
{
BUILD_BUG_ON(offsetof(typeof(*flow), dst) !=
offsetof(typeof(*flow), src) + sizeof(flow->src));
memcpy(&flow->src, &iph->saddr, sizeof(flow->src) + sizeof(flow->dst));
}
static bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow)
{
int poff, nhoff = skb_network_offset(skb);
u8 ip_proto;
__be16 proto = skb->protocol;
memset(flow, 0, sizeof(*flow));
again:
switch (proto) {
case __constant_htons(ETH_P_IP): {
const struct iphdr *iph;
struct iphdr _iph;
ip:
iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
if (!iph)
return false;
if (ip_is_fragment(iph))
ip_proto = 0;
else
ip_proto = iph->protocol;
iph_to_flow_copy_addrs(flow, iph);
nhoff += iph->ihl * 4;
break;
}
case __constant_htons(ETH_P_IPV6): {
const struct ipv6hdr *iph;
struct ipv6hdr _iph;
ipv6:
iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
if (!iph)
return false;
ip_proto = iph->nexthdr;
flow->src = (__force __be32)ipv6_addr_hash(&iph->saddr);
flow->dst = (__force __be32)ipv6_addr_hash(&iph->daddr);
nhoff += sizeof(struct ipv6hdr);
break;
}
case __constant_htons(ETH_P_8021Q): {
const struct vlan_hdr *vlan;
struct vlan_hdr _vlan;
vlan = skb_header_pointer(skb, nhoff, sizeof(_vlan), &_vlan);
if (!vlan)
return false;
proto = vlan->h_vlan_encapsulated_proto;
nhoff += sizeof(*vlan);
goto again;
}
case __constant_htons(ETH_P_PPP_SES): {
struct {
struct pppoe_hdr hdr;
__be16 proto;
} *hdr, _hdr;
hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr);
if (!hdr)
return false;
proto = hdr->proto;
nhoff += PPPOE_SES_HLEN;
switch (proto) {
case __constant_htons(PPP_IP):
goto ip;
case __constant_htons(PPP_IPV6):
goto ipv6;
default:
return false;
}
}
default:
return false;
}
switch (ip_proto) {
case IPPROTO_GRE: {
struct gre_hdr {
__be16 flags;
__be16 proto;
} *hdr, _hdr;
hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr);
if (!hdr)
return false;
/*
* Only look inside GRE if version zero and no
* routing
*/
if (!(hdr->flags & (GRE_VERSION|GRE_ROUTING))) {
proto = hdr->proto;
nhoff += 4;
if (hdr->flags & GRE_CSUM)
nhoff += 4;
if (hdr->flags & GRE_KEY)
nhoff += 4;
if (hdr->flags & GRE_SEQ)
nhoff += 4;
if (proto == htons(ETH_P_TEB)) {
const struct ethhdr *eth;
struct ethhdr _eth;
eth = skb_header_pointer(skb, nhoff,
sizeof(_eth), &_eth);
if (!eth)
return false;
proto = eth->h_proto;
nhoff += sizeof(*eth);
}
goto again;
}
break;
}
case IPPROTO_IPIP:
goto again;
default:
break;
}
flow->ip_proto = ip_proto;
poff = proto_ports_offset(ip_proto);
if (poff >= 0) {
__be32 *ports, _ports;
nhoff += poff;
ports = skb_header_pointer(skb, nhoff, sizeof(_ports), &_ports);
if (ports)
flow->ports = *ports;
}
flow->thoff = (u16) nhoff;
return true;
}
static u32 hashrnd __read_mostly;
static void init_hashrnd(void)
{
if (likely(hashrnd))
return;
get_random_bytes(&hashrnd, sizeof(hashrnd));
}
u32 __skb_get_rxhash(struct sk_buff *skb)
{
struct flow_keys keys;
u32 hash;
if (!skb_flow_dissect(skb, &keys))
return 0;
/* get a consistent hash (same value on both flow directions) */
if (((__force u32)keys.dst < (__force u32)keys.src) ||
(((__force u32)keys.dst == (__force u32)keys.src) &&
((__force u16)keys.port16[1] < (__force u16)keys.port16[0]))) {
swap(keys.dst, keys.src);
swap(keys.port16[0], keys.port16[1]);
}
init_hashrnd();
hash = jhash_3words((__force u32)keys.dst,
(__force u32)keys.src,
(__force u32)keys.ports, hashrnd);
if (!hash)
hash = 1;
#if LINUX_VERSION_CODE > KERNEL_VERSION(2,6,34)
skb->rxhash = hash;
#endif
return hash;
}
#endif
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