net/core/flow_dissector.c - maze/linux - Git at Google

 #include <linux/skbuff.h>
 #include <linux/export.h>
 #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));
 }

 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_8021AD):
 	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:
 		proto = htons(ETH_P_IP);
 		goto ip;
 	case IPPROTO_IPV6:
 		proto = htons(ETH_P_IPV6);
 		goto ipv6;
 	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;
 }
 EXPORT_SYMBOL(skb_flow_dissect);

 static u32 hashrnd __read_mostly;

 /*
  * __skb_get_rxhash: calculate a flow hash based on src/dst addresses
  * and src/dst port numbers.  Sets rxhash in skb to non-zero hash value
  * on success, zero indicates no valid hash.  Also, sets l4_rxhash in skb
  * if hash is a canonical 4-tuple hash over transport ports.
  */
 void __skb_get_rxhash(struct sk_buff *skb)
 {
 	struct flow_keys keys;
 	u32 hash;

 	if (!skb_flow_dissect(skb, &keys))
 		return;

 	if (keys.ports)
 		skb->l4_rxhash = 1;

 	/* 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]);
 	}

 	hash = jhash_3words((__force u32)keys.dst,
 			    (__force u32)keys.src,
 			    (__force u32)keys.ports, hashrnd);
 	if (!hash)
 		hash = 1;

 	skb->rxhash = hash;
 }
 EXPORT_SYMBOL(__skb_get_rxhash);

 /*
  * Returns a Tx hash based on the given packet descriptor a Tx queues' number
  * to be used as a distribution range.
  */
 u16 __skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb,
 		  unsigned int num_tx_queues)
 {
 	u32 hash;
 	u16 qoffset = 0;
 	u16 qcount = num_tx_queues;

 	if (skb_rx_queue_recorded(skb)) {
 		hash = skb_get_rx_queue(skb);
 		while (unlikely(hash >= num_tx_queues))
 			hash -= num_tx_queues;
 		return hash;
 	}

 	if (dev->num_tc) {
 		u8 tc = netdev_get_prio_tc_map(dev, skb->priority);
 		qoffset = dev->tc_to_txq[tc].offset;
 		qcount = dev->tc_to_txq[tc].count;
 	}

 	if (skb->sk && skb->sk->sk_hash)
 		hash = skb->sk->sk_hash;
 	else
 		hash = (__force u16) skb->protocol;
 	hash = jhash_1word(hash, hashrnd);

 	return (u16) (((u64) hash * qcount) >> 32) + qoffset;
 }
 EXPORT_SYMBOL(__skb_tx_hash);

 /* __skb_get_poff() returns the offset to the payload as far as it could
  * be dissected. The main user is currently BPF, so that we can dynamically
  * truncate packets without needing to push actual payload to the user
  * space and can analyze headers only, instead.
  */
 u32 __skb_get_poff(const struct sk_buff *skb)
 {
 	struct flow_keys keys;
 	u32 poff = 0;

 	if (!skb_flow_dissect(skb, &keys))
 		return 0;

 	poff += keys.thoff;
 	switch (keys.ip_proto) {
 	case IPPROTO_TCP: {
 		const struct tcphdr *tcph;
 		struct tcphdr _tcph;

 		tcph = skb_header_pointer(skb, poff, sizeof(_tcph), &_tcph);
 		if (!tcph)
 			return poff;

 		poff += max_t(u32, sizeof(struct tcphdr), tcph->doff * 4);
 		break;
 	}
 	case IPPROTO_UDP:
 	case IPPROTO_UDPLITE:
 		poff += sizeof(struct udphdr);
 		break;
 	/* For the rest, we do not really care about header
 	 * extensions at this point for now.
 	 */
 	case IPPROTO_ICMP:
 		poff += sizeof(struct icmphdr);
 		break;
 	case IPPROTO_ICMPV6:
 		poff += sizeof(struct icmp6hdr);
 		break;
 	case IPPROTO_IGMP:
 		poff += sizeof(struct igmphdr);
 		break;
 	case IPPROTO_DCCP:
 		poff += sizeof(struct dccp_hdr);
 		break;
 	case IPPROTO_SCTP:
 		poff += sizeof(struct sctphdr);
 		break;
 	}

 	return poff;
 }

 static inline u16 dev_cap_txqueue(struct net_device *dev, u16 queue_index)
 {
 	if (unlikely(queue_index >= dev->real_num_tx_queues)) {
 		net_warn_ratelimited("%s selects TX queue %d, but real number of TX queues is %d\n",
 				     dev->name, queue_index,
 				     dev->real_num_tx_queues);
 		return 0;
 	}
 	return queue_index;
 }

 static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
 {
 #ifdef CONFIG_XPS
 	struct xps_dev_maps *dev_maps;
 	struct xps_map *map;
 	int queue_index = -1;

 	rcu_read_lock();
 	dev_maps = rcu_dereference(dev->xps_maps);
 	if (dev_maps) {
 		map = rcu_dereference(
 		    dev_maps->cpu_map[raw_smp_processor_id()]);
 		if (map) {
 			if (map->len == 1)
 				queue_index = map->queues[0];
 			else {
 				u32 hash;
 				if (skb->sk && skb->sk->sk_hash)
 					hash = skb->sk->sk_hash;
 				else
 					hash = (__force u16) skb->protocol ^
 					    skb->rxhash;
 				hash = jhash_1word(hash, hashrnd);
 				queue_index = map->queues[
 				    ((u64)hash * map->len) >> 32];
 			}
 			if (unlikely(queue_index >= dev->real_num_tx_queues))
 				queue_index = -1;
 		}
 	}
 	rcu_read_unlock();

 	return queue_index;
 #else
 	return -1;
 #endif
 }

 u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb)
 {
 	struct sock *sk = skb->sk;
 	int queue_index = sk_tx_queue_get(sk);

 	if (queue_index < 0 || skb->ooo_okay ||
 	    queue_index >= dev->real_num_tx_queues) {
 		int new_index = get_xps_queue(dev, skb);
 		if (new_index < 0)
 			new_index = skb_tx_hash(dev, skb);

 		if (queue_index != new_index && sk &&
 		    rcu_access_pointer(sk->sk_dst_cache))
 			sk_tx_queue_set(sk, new_index);

 		queue_index = new_index;
 	}

 	return queue_index;
 }
 EXPORT_SYMBOL(__netdev_pick_tx);

 struct netdev_queue *netdev_pick_tx(struct net_device *dev,
 				    struct sk_buff *skb)
 {
 	int queue_index = 0;

 	if (dev->real_num_tx_queues != 1) {
 		const struct net_device_ops *ops = dev->netdev_ops;
 		if (ops->ndo_select_queue)
 			queue_index = ops->ndo_select_queue(dev, skb);
 		else
 			queue_index = __netdev_pick_tx(dev, skb);
 		queue_index = dev_cap_txqueue(dev, queue_index);
 	}

 	skb_set_queue_mapping(skb, queue_index);
 	return netdev_get_tx_queue(dev, queue_index);
 }

 static int __init initialize_hashrnd(void)
 {
 	get_random_bytes(&hashrnd, sizeof(hashrnd));
 	return 0;
 }

 late_initcall_sync(initialize_hashrnd);
	#include <linux/skbuff.h>
	#include <linux/export.h>
	#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));
	}

	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_8021AD):
	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:
	proto = htons(ETH_P_IP);
	goto ip;
	case IPPROTO_IPV6:
	proto = htons(ETH_P_IPV6);
	goto ipv6;
	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;
	}
	EXPORT_SYMBOL(skb_flow_dissect);

	static u32 hashrnd __read_mostly;

	/*
	* __skb_get_rxhash: calculate a flow hash based on src/dst addresses
	* and src/dst port numbers. Sets rxhash in skb to non-zero hash value
	* on success, zero indicates no valid hash. Also, sets l4_rxhash in skb
	* if hash is a canonical 4-tuple hash over transport ports.
	*/
	void __skb_get_rxhash(struct sk_buff *skb)
	{
	struct flow_keys keys;
	u32 hash;

	if (!skb_flow_dissect(skb, &keys))
	return;

	if (keys.ports)
	skb->l4_rxhash = 1;

	/* 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]);
	}

	hash = jhash_3words((__force u32)keys.dst,
	(__force u32)keys.src,
	(__force u32)keys.ports, hashrnd);
	if (!hash)
	hash = 1;

	skb->rxhash = hash;
	}
	EXPORT_SYMBOL(__skb_get_rxhash);

	/*
	* Returns a Tx hash based on the given packet descriptor a Tx queues' number
	* to be used as a distribution range.
	*/
	u16 __skb_tx_hash(const struct net_device dev, const struct sk_buff skb,
	unsigned int num_tx_queues)
	{
	u32 hash;
	u16 qoffset = 0;
	u16 qcount = num_tx_queues;

	if (skb_rx_queue_recorded(skb)) {
	hash = skb_get_rx_queue(skb);
	while (unlikely(hash >= num_tx_queues))
	hash -= num_tx_queues;
	return hash;
	}

	if (dev->num_tc) {
	u8 tc = netdev_get_prio_tc_map(dev, skb->priority);
	qoffset = dev->tc_to_txq[tc].offset;
	qcount = dev->tc_to_txq[tc].count;
	}

	if (skb->sk && skb->sk->sk_hash)
	hash = skb->sk->sk_hash;
	else
	hash = (__force u16) skb->protocol;
	hash = jhash_1word(hash, hashrnd);

	return (u16) (((u64) hash * qcount) >> 32) + qoffset;
	}
	EXPORT_SYMBOL(__skb_tx_hash);

	/* __skb_get_poff() returns the offset to the payload as far as it could
	* be dissected. The main user is currently BPF, so that we can dynamically
	* truncate packets without needing to push actual payload to the user
	* space and can analyze headers only, instead.
	*/
	u32 __skb_get_poff(const struct sk_buff *skb)
	{
	struct flow_keys keys;
	u32 poff = 0;

	if (!skb_flow_dissect(skb, &keys))
	return 0;

	poff += keys.thoff;
	switch (keys.ip_proto) {
	case IPPROTO_TCP: {
	const struct tcphdr *tcph;
	struct tcphdr _tcph;

	tcph = skb_header_pointer(skb, poff, sizeof(_tcph), &_tcph);
	if (!tcph)
	return poff;

	poff += max_t(u32, sizeof(struct tcphdr), tcph->doff * 4);
	break;
	}
	case IPPROTO_UDP:
	case IPPROTO_UDPLITE:
	poff += sizeof(struct udphdr);
	break;
	/* For the rest, we do not really care about header
	* extensions at this point for now.
	*/
	case IPPROTO_ICMP:
	poff += sizeof(struct icmphdr);
	break;
	case IPPROTO_ICMPV6:
	poff += sizeof(struct icmp6hdr);
	break;
	case IPPROTO_IGMP:
	poff += sizeof(struct igmphdr);
	break;
	case IPPROTO_DCCP:
	poff += sizeof(struct dccp_hdr);
	break;
	case IPPROTO_SCTP:
	poff += sizeof(struct sctphdr);
	break;
	}

	return poff;
	}

	static inline u16 dev_cap_txqueue(struct net_device *dev, u16 queue_index)
	{
	if (unlikely(queue_index >= dev->real_num_tx_queues)) {
	net_warn_ratelimited("%s selects TX queue %d, but real number of TX queues is %d\n",
	dev->name, queue_index,
	dev->real_num_tx_queues);
	return 0;
	}
	return queue_index;
	}

	static inline int get_xps_queue(struct net_device dev, struct sk_buff skb)
	{
	#ifdef CONFIG_XPS
	struct xps_dev_maps *dev_maps;
	struct xps_map *map;
	int queue_index = -1;

	rcu_read_lock();
	dev_maps = rcu_dereference(dev->xps_maps);
	if (dev_maps) {
	map = rcu_dereference(
	dev_maps->cpu_map[raw_smp_processor_id()]);
	if (map) {
	if (map->len == 1)
	queue_index = map->queues[0];
	else {
	u32 hash;
	if (skb->sk && skb->sk->sk_hash)
	hash = skb->sk->sk_hash;
	else
	hash = (__force u16) skb->protocol ^
	skb->rxhash;
	hash = jhash_1word(hash, hashrnd);
	queue_index = map->queues[
	((u64)hash * map->len) >> 32];
	}
	if (unlikely(queue_index >= dev->real_num_tx_queues))
	queue_index = -1;
	}
	}
	rcu_read_unlock();

	return queue_index;
	#else
	return -1;
	#endif
	}

	u16 __netdev_pick_tx(struct net_device dev, struct sk_buff skb)
	{
	struct sock *sk = skb->sk;
	int queue_index = sk_tx_queue_get(sk);

	if (queue_index < 0 \|\| skb->ooo_okay \|\|
	queue_index >= dev->real_num_tx_queues) {
	int new_index = get_xps_queue(dev, skb);
	if (new_index < 0)
	new_index = skb_tx_hash(dev, skb);

	if (queue_index != new_index && sk &&
	rcu_access_pointer(sk->sk_dst_cache))
	sk_tx_queue_set(sk, new_index);

	queue_index = new_index;
	}

	return queue_index;
	}
	EXPORT_SYMBOL(__netdev_pick_tx);

	struct netdev_queue netdev_pick_tx(struct net_device dev,
	struct sk_buff *skb)
	{
	int queue_index = 0;

	if (dev->real_num_tx_queues != 1) {
	const struct net_device_ops *ops = dev->netdev_ops;
	if (ops->ndo_select_queue)
	queue_index = ops->ndo_select_queue(dev, skb);
	else
	queue_index = __netdev_pick_tx(dev, skb);
	queue_index = dev_cap_txqueue(dev, queue_index);
	}

	skb_set_queue_mapping(skb, queue_index);
	return netdev_get_tx_queue(dev, queue_index);
	}

	static int __init initialize_hashrnd(void)
	{
	get_random_bytes(&hashrnd, sizeof(hashrnd));
	return 0;
	}

	late_initcall_sync(initialize_hashrnd);