[ovs.git] / datapath / flow.c

/*
 * Distributed under the terms of the GNU GPL version 2.
 * Copyright (c) 2007, 2008, 2009, 2010 Nicira Networks.
 *
 * Significant portions of this file may be copied from parts of the Linux
 * kernel, by Linus Torvalds and others.
 */

#include "flow.h"
#include "datapath.h"
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <net/llc_pdu.h>
#include <linux/kernel.h>
#include <linux/jhash.h>
#include <linux/jiffies.h>
#include <linux/llc.h>
#include <linux/module.h>
#include <linux/in.h>
#include <linux/rcupdate.h>
#include <linux/if_arp.h>
#include <linux/if_ether.h>
#include <linux/ip.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/icmp.h>
#include <net/inet_ecn.h>
#include <net/ip.h>

#include "compat.h"

struct kmem_cache *flow_cache;
static unsigned int hash_seed;

static inline bool arphdr_ok(struct sk_buff *skb)
{
	return skb->len >= skb_network_offset(skb) + sizeof(struct arp_eth_header);
}

static inline int check_iphdr(struct sk_buff *skb)
{
	unsigned int nh_ofs = skb_network_offset(skb);
	unsigned int ip_len;

	if (skb->len < nh_ofs + sizeof(struct iphdr))
		return -EINVAL;

	ip_len = ip_hdrlen(skb);
	if (ip_len < sizeof(struct iphdr) || skb->len < nh_ofs + ip_len)
		return -EINVAL;

	/*
	 * Pull enough header bytes to account for the IP header plus the
	 * longest transport header that we parse, currently 20 bytes for TCP.
	 */
	if (!pskb_may_pull(skb, min(nh_ofs + ip_len + 20, skb->len)))
		return -ENOMEM;

	skb_set_transport_header(skb, nh_ofs + ip_len);
	return 0;
}

static inline bool tcphdr_ok(struct sk_buff *skb)
{
	int th_ofs = skb_transport_offset(skb);
	if (skb->len >= th_ofs + sizeof(struct tcphdr)) {
		int tcp_len = tcp_hdrlen(skb);
		return (tcp_len >= sizeof(struct tcphdr)
			&& skb->len >= th_ofs + tcp_len);
	}
	return false;
}

static inline bool udphdr_ok(struct sk_buff *skb)
{
	return skb->len >= skb_transport_offset(skb) + sizeof(struct udphdr);
}

static inline bool icmphdr_ok(struct sk_buff *skb)
{
	return skb->len >= skb_transport_offset(skb) + sizeof(struct icmphdr);
}

#define TCP_FLAGS_OFFSET 13
#define TCP_FLAG_MASK 0x3f

void flow_used(struct sw_flow *flow, struct sk_buff *skb)
{
	u8 tcp_flags = 0;

	if (flow->key.dl_type == htons(ETH_P_IP) &&
	    flow->key.nw_proto == IPPROTO_TCP) {
		u8 *tcp = (u8 *)tcp_hdr(skb);
		tcp_flags = *(tcp + TCP_FLAGS_OFFSET) & TCP_FLAG_MASK;
	}

	spin_lock_bh(&flow->lock);
	flow->used = jiffies;
	flow->packet_count++;
	flow->byte_count += skb->len;
	flow->tcp_flags |= tcp_flags;
	spin_unlock_bh(&flow->lock);
}

struct sw_flow_actions *flow_actions_alloc(size_t n_actions)
{
	struct sw_flow_actions *sfa;

	if (n_actions > (PAGE_SIZE - sizeof *sfa) / sizeof(union odp_action))
		return ERR_PTR(-EINVAL);

	sfa = kmalloc(sizeof *sfa + n_actions * sizeof(union odp_action),
		      GFP_KERNEL);
	if (!sfa)
		return ERR_PTR(-ENOMEM);

	sfa->n_actions = n_actions;
	return sfa;
}


/* Frees 'flow' immediately. */
static void flow_free(struct sw_flow *flow)
{
	if (unlikely(!flow))
		return;
	kfree(flow->sf_acts);
	kmem_cache_free(flow_cache, flow);
}

void flow_free_tbl(struct tbl_node *node)
{
	struct sw_flow *flow = flow_cast(node);
	flow_free(flow);
}

/* RCU callback used by flow_deferred_free. */
static void rcu_free_flow_callback(struct rcu_head *rcu)
{
	struct sw_flow *flow = container_of(rcu, struct sw_flow, rcu);
	flow_free(flow);
}

/* Schedules 'flow' to be freed after the next RCU grace period.
 * The caller must hold rcu_read_lock for this to be sensible. */
void flow_deferred_free(struct sw_flow *flow)
{
	call_rcu(&flow->rcu, rcu_free_flow_callback);
}

/* RCU callback used by flow_deferred_free_acts. */
static void rcu_free_acts_callback(struct rcu_head *rcu)
{
	struct sw_flow_actions *sf_acts = container_of(rcu, 
			struct sw_flow_actions, rcu);
	kfree(sf_acts);
}

/* Schedules 'sf_acts' to be freed after the next RCU grace period.
 * The caller must hold rcu_read_lock for this to be sensible. */
void flow_deferred_free_acts(struct sw_flow_actions *sf_acts)
{
	call_rcu(&sf_acts->rcu, rcu_free_acts_callback);
}

static void parse_vlan(struct sk_buff *skb, struct odp_flow_key *key)
{
	struct qtag_prefix {
		__be16 eth_type; /* ETH_P_8021Q */
		__be16 tci;
	};
	struct qtag_prefix *qp;

	if (skb->len < sizeof(struct qtag_prefix) + sizeof(__be16))
		return;

	qp = (struct qtag_prefix *) skb->data;
	key->dl_vlan = qp->tci & htons(VLAN_VID_MASK);
	key->dl_vlan_pcp = (ntohs(qp->tci) & VLAN_PCP_MASK) >> VLAN_PCP_SHIFT;
	__skb_pull(skb, sizeof(struct qtag_prefix));
}

static __be16 parse_ethertype(struct sk_buff *skb)
{
	struct llc_snap_hdr {
		u8  dsap;  /* Always 0xAA */
		u8  ssap;  /* Always 0xAA */
		u8  ctrl;
		u8  oui[3];
		u16 ethertype;
	};
	struct llc_snap_hdr *llc;
	__be16 proto;

	proto = *(__be16 *) skb->data;
	__skb_pull(skb, sizeof(__be16));

	if (ntohs(proto) >= ODP_DL_TYPE_ETH2_CUTOFF)
		return proto;

	if (unlikely(skb->len < sizeof(struct llc_snap_hdr)))
		return htons(ODP_DL_TYPE_NOT_ETH_TYPE);

	llc = (struct llc_snap_hdr *) skb->data;
	if (llc->dsap != LLC_SAP_SNAP ||
	    llc->ssap != LLC_SAP_SNAP ||
	    (llc->oui[0] | llc->oui[1] | llc->oui[2]) != 0)
		return htons(ODP_DL_TYPE_NOT_ETH_TYPE);

	__skb_pull(skb, sizeof(struct llc_snap_hdr));
	return llc->ethertype;
}

/**
 * flow_extract - extracts a flow key from an Ethernet frame.
 * @skb: sk_buff that contains the frame, with skb->data pointing to the
 * Ethernet header
 * @in_port: port number on which @skb was received.
 * @key: output flow key
 *
 * The caller must ensure that skb->len >= ETH_HLEN.
 *
 * Returns 0 if successful, otherwise a negative errno value.
 *
 * Initializes @skb header pointers as follows:
 *
 *    - skb->mac_header: the Ethernet header.
 *
 *    - skb->network_header: just past the Ethernet header, or just past the
 *      VLAN header, to the first byte of the Ethernet payload.
 *
 *    - skb->transport_header: If key->dl_type is ETH_P_IP on output, then just
 *      past the IPv4 header, if one is present and of a correct length,
 *      otherwise the same as skb->network_header.  For other key->dl_type
 *      values it is left untouched.
 *
 * Sets OVS_CB(skb)->is_frag to %true if @skb is an IPv4 fragment, otherwise to
 * %false.
 */
int flow_extract(struct sk_buff *skb, u16 in_port, struct odp_flow_key *key)
{
	struct ethhdr *eth;

	memset(key, 0, sizeof *key);
	key->tun_id = OVS_CB(skb)->tun_id;
	key->in_port = in_port;
	key->dl_vlan = htons(ODP_VLAN_NONE);
	OVS_CB(skb)->is_frag = false;

	/*
	 * We would really like to pull as many bytes as we could possibly
	 * want to parse into the linear data area.  Currently that is:
	 *
	 *    14     Ethernet header
	 *     4     VLAN header
	 *    60     max IP header with options
	 *    20     max TCP/UDP/ICMP header (don't care about options)
	 *    --
	 *    98
	 *
	 * But Xen only allocates 64 or 72 bytes for the linear data area in
	 * netback, which means that we would reallocate and copy the skb's
	 * linear data on every packet if we did that.  So instead just pull 64
	 * bytes, which is always sufficient without IP options, and then check
	 * whether we need to pull more later when we look at the IP header.
	 */
	if (!pskb_may_pull(skb, min(skb->len, 64u)))
		return -ENOMEM;

	skb_reset_mac_header(skb);

	/* Link layer. */
	eth = eth_hdr(skb);
	memcpy(key->dl_src, eth->h_source, ETH_ALEN);
	memcpy(key->dl_dst, eth->h_dest, ETH_ALEN);

	/* dl_type, dl_vlan, dl_vlan_pcp. */
	__skb_pull(skb, 2 * ETH_ALEN);
	if (eth->h_proto == htons(ETH_P_8021Q))
		parse_vlan(skb, key);
	key->dl_type = parse_ethertype(skb);
	skb_reset_network_header(skb);
	__skb_push(skb, skb->data - (unsigned char *)eth);

	/* Network layer. */
	if (key->dl_type == htons(ETH_P_IP)) {
		struct iphdr *nh;
		int error;

		error = check_iphdr(skb);
		if (unlikely(error)) {
			if (error == -EINVAL) {
				skb->transport_header = skb->network_header;
				return 0;
			}
			return error;
		}

		nh = ip_hdr(skb);
		key->nw_src = nh->saddr;
		key->nw_dst = nh->daddr;
		key->nw_tos = nh->tos & ~INET_ECN_MASK;
		key->nw_proto = nh->protocol;

		/* Transport layer. */
		if (!(nh->frag_off & htons(IP_MF | IP_OFFSET))) {
			if (key->nw_proto == IPPROTO_TCP) {
				if (tcphdr_ok(skb)) {
					struct tcphdr *tcp = tcp_hdr(skb);
					key->tp_src = tcp->source;
					key->tp_dst = tcp->dest;
				}
			} else if (key->nw_proto == IPPROTO_UDP) {
				if (udphdr_ok(skb)) {
					struct udphdr *udp = udp_hdr(skb);
					key->tp_src = udp->source;
					key->tp_dst = udp->dest;
				}
			} else if (key->nw_proto == IPPROTO_ICMP) {
				if (icmphdr_ok(skb)) {
					struct icmphdr *icmp = icmp_hdr(skb);
					/* The ICMP type and code fields use the 16-bit
					 * transport port fields, so we need to store them
					 * in 16-bit network byte order. */
					key->tp_src = htons(icmp->type);
					key->tp_dst = htons(icmp->code);
				}
			}
		} else {
			OVS_CB(skb)->is_frag = true;
		}
	} else if (key->dl_type == htons(ETH_P_ARP) && arphdr_ok(skb)) {
		struct arp_eth_header *arp;

		arp = (struct arp_eth_header *)skb_network_header(skb);

		if (arp->ar_hrd == htons(ARPHRD_ETHER)
				&& arp->ar_pro == htons(ETH_P_IP)
				&& arp->ar_hln == ETH_ALEN
				&& arp->ar_pln == 4) {

			/* We only match on the lower 8 bits of the opcode. */
			if (ntohs(arp->ar_op) <= 0xff) {
				key->nw_proto = ntohs(arp->ar_op);
			}

			if (key->nw_proto == ARPOP_REQUEST 
					|| key->nw_proto == ARPOP_REPLY) {
				memcpy(&key->nw_src, arp->ar_sip, sizeof(key->nw_src));
				memcpy(&key->nw_dst, arp->ar_tip, sizeof(key->nw_dst));
			}
		}
	}
	return 0;
}

u32 flow_hash(const struct odp_flow_key *key)
{
	return jhash2((u32*)key, sizeof *key / sizeof(u32), hash_seed);
}

int flow_cmp(const struct tbl_node *node, void *key2_)
{
	const struct odp_flow_key *key1 = &flow_cast(node)->key;
	const struct odp_flow_key *key2 = key2_;

	return !memcmp(key1, key2, sizeof(struct odp_flow_key));
}

/* Initializes the flow module.
 * Returns zero if successful or a negative error code. */
int flow_init(void)
{
	flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow), 0,
					0, NULL);
	if (flow_cache == NULL)
		return -ENOMEM;

	get_random_bytes(&hash_seed, sizeof hash_seed);

	return 0;
}

/* Uninitializes the flow module. */
void flow_exit(void)
{
	kmem_cache_destroy(flow_cache);
}
Commit	Line	Data
064af421 BP	1	/*
064af421 BP	2	* Distributed under the terms of the GNU GPL version 2.
834377ea	3	* Copyright (c) 2007, 2008, 2009, 2010 Nicira Networks.
a14bc59f BP	4	*
	5	* Significant portions of this file may be copied from parts of the Linux
	6	* kernel, by Linus Torvalds and others.
064af421 BP	7	*/
	8
	9	#include "flow.h"
f5e86186	10	#include "datapath.h"
064af421 BP	11	#include <linux/netdevice.h>
	12	#include <linux/etherdevice.h>
	13	#include <linux/if_ether.h>
	14	#include <linux/if_vlan.h>
	15	#include <net/llc_pdu.h>
	16	#include <linux/kernel.h>
8d5ebd83	17	#include <linux/jhash.h>
064af421 BP	18	#include <linux/jiffies.h>
	19	#include <linux/llc.h>
	20	#include <linux/module.h>
	21	#include <linux/in.h>
	22	#include <linux/rcupdate.h>
a26ef517	23	#include <linux/if_arp.h>
064af421 BP	24	#include <linux/if_ether.h>
	25	#include <linux/ip.h>
	26	#include <linux/tcp.h>
	27	#include <linux/udp.h>
	28	#include <linux/icmp.h>
3c5f6de3	29	#include <net/inet_ecn.h>
064af421 BP	30	#include <net/ip.h>
	31
	32	#include "compat.h"
	33
	34	struct kmem_cache *flow_cache;
8d5ebd83	35	static unsigned int hash_seed;
064af421	36
e819fb47	37	static inline bool arphdr_ok(struct sk_buff *skb)
a26ef517	38	{
7d0ab001	39	return skb->len >= skb_network_offset(skb) + sizeof(struct arp_eth_header);
a26ef517 JP	40	}
a26ef517 JP	41
4c1ad233	42	static inline int check_iphdr(struct sk_buff *skb)
064af421	43	{
4c1ad233 BP	44	unsigned int nh_ofs = skb_network_offset(skb);
	45	unsigned int ip_len;
	46
	47	if (skb->len < nh_ofs + sizeof(struct iphdr))
	48	return -EINVAL;
	49
	50	ip_len = ip_hdrlen(skb);
	51	if (ip_len < sizeof(struct iphdr) \|\| skb->len < nh_ofs + ip_len)
	52	return -EINVAL;
	53
	54	/*
	55	* Pull enough header bytes to account for the IP header plus the
	56	* longest transport header that we parse, currently 20 bytes for TCP.
	57	*/
	58	if (!pskb_may_pull(skb, min(nh_ofs + ip_len + 20, skb->len)))
	59	return -ENOMEM;
	60
	61	skb_set_transport_header(skb, nh_ofs + ip_len);
	62	return 0;
064af421 BP	63	}
064af421 BP	64
e819fb47	65	static inline bool tcphdr_ok(struct sk_buff *skb)
064af421 BP	66	{
064af421 BP	67	int th_ofs = skb_transport_offset(skb);
7d0ab001	68	if (skb->len >= th_ofs + sizeof(struct tcphdr)) {
064af421 BP	69	int tcp_len = tcp_hdrlen(skb);
	70	return (tcp_len >= sizeof(struct tcphdr)
	71	&& skb->len >= th_ofs + tcp_len);
	72	}
e819fb47	73	return false;
064af421 BP	74	}
064af421 BP	75
e819fb47	76	static inline bool udphdr_ok(struct sk_buff *skb)
064af421	77	{
7d0ab001	78	return skb->len >= skb_transport_offset(skb) + sizeof(struct udphdr);
064af421 BP	79	}
064af421 BP	80
e819fb47	81	static inline bool icmphdr_ok(struct sk_buff *skb)
064af421	82	{
7d0ab001	83	return skb->len >= skb_transport_offset(skb) + sizeof(struct icmphdr);
064af421 BP	84	}
	85
	86	#define TCP_FLAGS_OFFSET 13
	87	#define TCP_FLAG_MASK 0x3f
	88
064af421 BP	89	void flow_used(struct sw_flow flow, struct sk_buff skb)
064af421 BP	90	{
064af421 BP	91	u8 tcp_flags = 0;
064af421 BP	92
abfec865 BP	93	if (flow->key.dl_type == htons(ETH_P_IP) &&
	94	flow->key.nw_proto == IPPROTO_TCP) {
	95	u8 tcp = (u8 )tcp_hdr(skb);
	96	tcp_flags = *(tcp + TCP_FLAGS_OFFSET) & TCP_FLAG_MASK;
064af421 BP	97	}
064af421 BP	98
f2459fe7	99	spin_lock_bh(&flow->lock);
6bfafa55	100	flow->used = jiffies;
064af421 BP	101	flow->packet_count++;
	102	flow->byte_count += skb->len;
	103	flow->tcp_flags \|= tcp_flags;
f2459fe7	104	spin_unlock_bh(&flow->lock);
064af421 BP	105	}
	106
	107	struct sw_flow_actions *flow_actions_alloc(size_t n_actions)
	108	{
	109	struct sw_flow_actions *sfa;
	110
	111	if (n_actions > (PAGE_SIZE - sizeof *sfa) / sizeof(union odp_action))
	112	return ERR_PTR(-EINVAL);
	113
	114	sfa = kmalloc(sizeof sfa + n_actions sizeof(union odp_action),
	115	GFP_KERNEL);
	116	if (!sfa)
	117	return ERR_PTR(-ENOMEM);
	118
	119	sfa->n_actions = n_actions;
	120	return sfa;
	121	}
	122
	123
	124	/* Frees 'flow' immediately. */
8d5ebd83	125	static void flow_free(struct sw_flow *flow)
064af421 BP	126	{
	127	if (unlikely(!flow))
	128	return;
	129	kfree(flow->sf_acts);
	130	kmem_cache_free(flow_cache, flow);
	131	}
	132
8d5ebd83 JG	133	void flow_free_tbl(struct tbl_node *node)
	134	{
	135	struct sw_flow *flow = flow_cast(node);
	136	flow_free(flow);
	137	}
	138
064af421 BP	139	/* RCU callback used by flow_deferred_free. */
	140	static void rcu_free_flow_callback(struct rcu_head *rcu)
	141	{
	142	struct sw_flow *flow = container_of(rcu, struct sw_flow, rcu);
	143	flow_free(flow);
	144	}
	145
	146	/* Schedules 'flow' to be freed after the next RCU grace period.
	147	* The caller must hold rcu_read_lock for this to be sensible. */
	148	void flow_deferred_free(struct sw_flow *flow)
	149	{
	150	call_rcu(&flow->rcu, rcu_free_flow_callback);
	151	}
	152
	153	/* RCU callback used by flow_deferred_free_acts. */
	154	static void rcu_free_acts_callback(struct rcu_head *rcu)
	155	{
	156	struct sw_flow_actions *sf_acts = container_of(rcu,
	157	struct sw_flow_actions, rcu);
	158	kfree(sf_acts);
	159	}
	160
	161	/* Schedules 'sf_acts' to be freed after the next RCU grace period.
	162	* The caller must hold rcu_read_lock for this to be sensible. */
	163	void flow_deferred_free_acts(struct sw_flow_actions *sf_acts)
	164	{
	165	call_rcu(&sf_acts->rcu, rcu_free_acts_callback);
	166	}
	167
50f06e16	168	static void parse_vlan(struct sk_buff skb, struct odp_flow_key key)
064af421	169	{
50f06e16 BP	170	struct qtag_prefix {
	171	__be16 eth_type; /* ETH_P_8021Q */
	172	__be16 tci;
	173	};
	174	struct qtag_prefix *qp;
	175
	176	if (skb->len < sizeof(struct qtag_prefix) + sizeof(__be16))
	177	return;
	178
	179	qp = (struct qtag_prefix *) skb->data;
	180	key->dl_vlan = qp->tci & htons(VLAN_VID_MASK);
	181	key->dl_vlan_pcp = (ntohs(qp->tci) & VLAN_PCP_MASK) >> VLAN_PCP_SHIFT;
	182	__skb_pull(skb, sizeof(struct qtag_prefix));
	183	}
	184
	185	static __be16 parse_ethertype(struct sk_buff *skb)
064af421	186	{
50f06e16 BP	187	struct llc_snap_hdr {
	188	u8 dsap; /* Always 0xAA */
	189	u8 ssap; /* Always 0xAA */
	190	u8 ctrl;
	191	u8 oui[3];
	192	u16 ethertype;
	193	};
	194	struct llc_snap_hdr *llc;
	195	__be16 proto;
	196
	197	proto = (__be16 ) skb->data;
	198	__skb_pull(skb, sizeof(__be16));
	199
	200	if (ntohs(proto) >= ODP_DL_TYPE_ETH2_CUTOFF)
	201	return proto;
	202
	203	if (unlikely(skb->len < sizeof(struct llc_snap_hdr)))
	204	return htons(ODP_DL_TYPE_NOT_ETH_TYPE);
	205
	206	llc = (struct llc_snap_hdr *) skb->data;
	207	if (llc->dsap != LLC_SAP_SNAP \|\|
	208	llc->ssap != LLC_SAP_SNAP \|\|
	209	(llc->oui[0] \| llc->oui[1] \| llc->oui[2]) != 0)
	210	return htons(ODP_DL_TYPE_NOT_ETH_TYPE);
	211
	212	__skb_pull(skb, sizeof(struct llc_snap_hdr));
	213	return llc->ethertype;
064af421 BP	214	}
064af421 BP	215
a31e0e31 BP	216	/**
	217	* flow_extract - extracts a flow key from an Ethernet frame.
	218	* @skb: sk_buff that contains the frame, with skb->data pointing to the
	219	* Ethernet header
	220	* @in_port: port number on which @skb was received.
	221	* @key: output flow key
	222	*
	223	* The caller must ensure that skb->len >= ETH_HLEN.
	224	*
4c1ad233 BP	225	* Returns 0 if successful, otherwise a negative errno value.
4c1ad233 BP	226	*
59a18f80 BP	227	* Initializes @skb header pointers as follows:
	228	*
	229	* - skb->mac_header: the Ethernet header.
	230	*
	231	* - skb->network_header: just past the Ethernet header, or just past the
	232	* VLAN header, to the first byte of the Ethernet payload.
	233	*
	234	* - skb->transport_header: If key->dl_type is ETH_P_IP on output, then just
	235	* past the IPv4 header, if one is present and of a correct length,
	236	* otherwise the same as skb->network_header. For other key->dl_type
	237	* values it is left untouched.
	238	*
769f8ccd BP	239	* Sets OVS_CB(skb)->is_frag to %true if @skb is an IPv4 fragment, otherwise to
769f8ccd BP	240	* %false.
a31e0e31	241	*/
064af421 BP	242	int flow_extract(struct sk_buff skb, u16 in_port, struct odp_flow_key key)
	243	{
	244	struct ethhdr *eth;
064af421 BP	245
064af421 BP	246	memset(key, 0, sizeof *key);
659586ef	247	key->tun_id = OVS_CB(skb)->tun_id;
064af421	248	key->in_port = in_port;
659586ef	249	key->dl_vlan = htons(ODP_VLAN_NONE);
769f8ccd	250	OVS_CB(skb)->is_frag = false;
064af421	251
4c1ad233 BP	252	/*
	253	* We would really like to pull as many bytes as we could possibly
	254	* want to parse into the linear data area. Currently that is:
	255	*
	256	* 14 Ethernet header
	257	* 4 VLAN header
	258	* 60 max IP header with options
	259	* 20 max TCP/UDP/ICMP header (don't care about options)
	260	* --
	261	* 98
	262	*
	263	* But Xen only allocates 64 or 72 bytes for the linear data area in
	264	* netback, which means that we would reallocate and copy the skb's
	265	* linear data on every packet if we did that. So instead just pull 64
	266	* bytes, which is always sufficient without IP options, and then check
	267	* whether we need to pull more later when we look at the IP header.
	268	*/
d9fce1ca	269	if (!pskb_may_pull(skb, min(skb->len, 64u)))
4c1ad233	270	return -ENOMEM;
064af421 BP	271
064af421 BP	272	skb_reset_mac_header(skb);
064af421	273
50f06e16 BP	274	/* Link layer. */
50f06e16 BP	275	eth = eth_hdr(skb);
064af421 BP	276	memcpy(key->dl_src, eth->h_source, ETH_ALEN);
064af421 BP	277	memcpy(key->dl_dst, eth->h_dest, ETH_ALEN);
50f06e16 BP	278
	279	/* dl_type, dl_vlan, dl_vlan_pcp. */
	280	__skb_pull(skb, 2 * ETH_ALEN);
	281	if (eth->h_proto == htons(ETH_P_8021Q))
	282	parse_vlan(skb, key);
	283	key->dl_type = parse_ethertype(skb);
	284	skb_reset_network_header(skb);
	285	__skb_push(skb, skb->data - (unsigned char *)eth);
064af421 BP	286
064af421 BP	287	/* Network layer. */
4c1ad233 BP	288	if (key->dl_type == htons(ETH_P_IP)) {
	289	struct iphdr *nh;
	290	int error;
	291
	292	error = check_iphdr(skb);
	293	if (unlikely(error)) {
	294	if (error == -EINVAL) {
	295	skb->transport_header = skb->network_header;
	296	return 0;
	297	}
	298	return error;
	299	}
	300
	301	nh = ip_hdr(skb);
064af421 BP	302	key->nw_src = nh->saddr;
064af421 BP	303	key->nw_dst = nh->daddr;
f5e86186	304	key->nw_tos = nh->tos & ~INET_ECN_MASK;
064af421	305	key->nw_proto = nh->protocol;
064af421 BP	306
	307	/* Transport layer. */
	308	if (!(nh->frag_off & htons(IP_MF \| IP_OFFSET))) {
	309	if (key->nw_proto == IPPROTO_TCP) {
	310	if (tcphdr_ok(skb)) {
	311	struct tcphdr *tcp = tcp_hdr(skb);
	312	key->tp_src = tcp->source;
	313	key->tp_dst = tcp->dest;
064af421 BP	314	}
	315	} else if (key->nw_proto == IPPROTO_UDP) {
	316	if (udphdr_ok(skb)) {
	317	struct udphdr *udp = udp_hdr(skb);
	318	key->tp_src = udp->source;
	319	key->tp_dst = udp->dest;
064af421 BP	320	}
	321	} else if (key->nw_proto == IPPROTO_ICMP) {
	322	if (icmphdr_ok(skb)) {
	323	struct icmphdr *icmp = icmp_hdr(skb);
	324	/* The ICMP type and code fields use the 16-bit
	325	* transport port fields, so we need to store them
	326	* in 16-bit network byte order. */
	327	key->tp_src = htons(icmp->type);
	328	key->tp_dst = htons(icmp->code);
064af421 BP	329	}
	330	}
	331	} else {
769f8ccd	332	OVS_CB(skb)->is_frag = true;
064af421	333	}
a26ef517 JP	334	} else if (key->dl_type == htons(ETH_P_ARP) && arphdr_ok(skb)) {
	335	struct arp_eth_header *arp;
	336
	337	arp = (struct arp_eth_header *)skb_network_header(skb);
	338
f5e86186	339	if (arp->ar_hrd == htons(ARPHRD_ETHER)
de3f65ea JP	340	&& arp->ar_pro == htons(ETH_P_IP)
	341	&& arp->ar_hln == ETH_ALEN
	342	&& arp->ar_pln == 4) {
	343
	344	/* We only match on the lower 8 bits of the opcode. */
	345	if (ntohs(arp->ar_op) <= 0xff) {
	346	key->nw_proto = ntohs(arp->ar_op);
	347	}
	348
	349	if (key->nw_proto == ARPOP_REQUEST
	350	\|\| key->nw_proto == ARPOP_REPLY) {
	351	memcpy(&key->nw_src, arp->ar_sip, sizeof(key->nw_src));
	352	memcpy(&key->nw_dst, arp->ar_tip, sizeof(key->nw_dst));
	353	}
	354	}
064af421	355	}
769f8ccd	356	return 0;
064af421 BP	357	}
064af421 BP	358
8d5ebd83 JG	359	u32 flow_hash(const struct odp_flow_key *key)
	360	{
	361	return jhash2((u32)key, sizeof key / sizeof(u32), hash_seed);
	362	}
	363
	364	int flow_cmp(const struct tbl_node node, void key2_)
	365	{
	366	const struct odp_flow_key *key1 = &flow_cast(node)->key;
	367	const struct odp_flow_key *key2 = key2_;
	368
	369	return !memcmp(key1, key2, sizeof(struct odp_flow_key));
	370	}
	371
064af421 BP	372	/* Initializes the flow module.
	373	* Returns zero if successful or a negative error code. */
	374	int flow_init(void)
	375	{
	376	flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow), 0,
	377	0, NULL);
	378	if (flow_cache == NULL)
	379	return -ENOMEM;
	380
8d5ebd83 JG	381	get_random_bytes(&hash_seed, sizeof hash_seed);
8d5ebd83 JG	382
064af421 BP	383	return 0;
	384	}
	385
	386	/* Uninitializes the flow module. */
	387	void flow_exit(void)
	388	{
	389	kmem_cache_destroy(flow_cache);
	390	}