LXR linux/net/core/flow

   1#include <linux/skbuff.h>
   2#include <linux/export.h>
   3#include <linux/ip.h>
   4#include <linux/ipv6.h>
   5#include <linux/if_vlan.h>
   6#include <net/ip.h>
   7#include <net/ipv6.h>
   8#include <linux/igmp.h>
   9#include <linux/icmp.h>
  10#include <linux/sctp.h>
  11#include <linux/dccp.h>
  12#include <linux/if_tunnel.h>
  13#include <linux/if_pppox.h>
  14#include <linux/ppp_defs.h>
  15#include <net/flow_keys.h>
  16
  17/* copy saddr & daddr, possibly using 64bit load/store
  18 * Equivalent to :      flow->src = iph->saddr;
  19 *                      flow->dst = iph->daddr;
  20 */
  21static void iph_to_flow_copy_addrs(struct flow_keys *flow, const struct iphdr *iph)
  22{
  23        BUILD_BUG_ON(offsetof(typeof(*flow), dst) !=
  24                     offsetof(typeof(*flow), src) + sizeof(flow->src));
  25        memcpy(&flow->src, &iph->saddr, sizeof(flow->src) + sizeof(flow->dst));
  26}
  27
  28bool skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow)
  29{
  30        int poff, nhoff = skb_network_offset(skb);
  31        u8 ip_proto;
  32        __be16 proto = skb->protocol;
  33
  34        memset(flow, 0, sizeof(*flow));
  35
  36again:
  37        switch (proto) {
  38        case __constant_htons(ETH_P_IP): {
  39                const struct iphdr *iph;
  40                struct iphdr _iph;
  41ip:
  42                iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
  43                if (!iph)
  44                        return false;
  45
  46                if (ip_is_fragment(iph))
  47                        ip_proto = 0;
  48                else
  49                        ip_proto = iph->protocol;
  50                iph_to_flow_copy_addrs(flow, iph);
  51                nhoff += iph->ihl * 4;
  52                break;
  53        }
  54        case __constant_htons(ETH_P_IPV6): {
  55                const struct ipv6hdr *iph;
  56                struct ipv6hdr _iph;
  57ipv6:
  58                iph = skb_header_pointer(skb, nhoff, sizeof(_iph), &_iph);
  59                if (!iph)
  60                        return false;
  61
  62                ip_proto = iph->nexthdr;
  63                flow->src = (__force __be32)ipv6_addr_hash(&iph->saddr);
  64                flow->dst = (__force __be32)ipv6_addr_hash(&iph->daddr);
  65                nhoff += sizeof(struct ipv6hdr);
  66                break;
  67        }
  68        case __constant_htons(ETH_P_8021AD):
  69        case __constant_htons(ETH_P_8021Q): {
  70                const struct vlan_hdr *vlan;
  71                struct vlan_hdr _vlan;
  72
  73                vlan = skb_header_pointer(skb, nhoff, sizeof(_vlan), &_vlan);
  74                if (!vlan)
  75                        return false;
  76
  77                proto = vlan->h_vlan_encapsulated_proto;
  78                nhoff += sizeof(*vlan);
  79                goto again;
  80        }
  81        case __constant_htons(ETH_P_PPP_SES): {
  82                struct {
  83                        struct pppoe_hdr hdr;
  84                        __be16 proto;
  85                } *hdr, _hdr;
  86                hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr);
  87                if (!hdr)
  88                        return false;
  89                proto = hdr->proto;
  90                nhoff += PPPOE_SES_HLEN;
  91                switch (proto) {
  92                case __constant_htons(PPP_IP):
  93                        goto ip;
  94                case __constant_htons(PPP_IPV6):
  95                        goto ipv6;
  96                default:
  97                        return false;
  98                }
  99        }
 100        default:
 101                return false;
 102        }
 103
 104        switch (ip_proto) {
 105        case IPPROTO_GRE: {
 106                struct gre_hdr {
 107                        __be16 flags;
 108                        __be16 proto;
 109                } *hdr, _hdr;
 110
 111                hdr = skb_header_pointer(skb, nhoff, sizeof(_hdr), &_hdr);
 112                if (!hdr)
 113                        return false;
 114                /*
 115                 * Only look inside GRE if version zero and no
 116                 * routing
 117                 */
 118                if (!(hdr->flags & (GRE_VERSION|GRE_ROUTING))) {
 119                        proto = hdr->proto;
 120                        nhoff += 4;
 121                        if (hdr->flags & GRE_CSUM)
 122                                nhoff += 4;
 123                        if (hdr->flags & GRE_KEY)
 124                                nhoff += 4;
 125                        if (hdr->flags & GRE_SEQ)
 126                                nhoff += 4;
 127                        if (proto == htons(ETH_P_TEB)) {
 128                                const struct ethhdr *eth;
 129                                struct ethhdr _eth;
 130
 131                                eth = skb_header_pointer(skb, nhoff,
 132                                                         sizeof(_eth), &_eth);
 133                                if (!eth)
 134                                        return false;
 135                                proto = eth->h_proto;
 136                                nhoff += sizeof(*eth);
 137                        }
 138                        goto again;
 139                }
 140                break;
 141        }
 142        case IPPROTO_IPIP:
 143                proto = htons(ETH_P_IP);
 144                goto ip;
 145        case IPPROTO_IPV6:
 146                proto = htons(ETH_P_IPV6);
 147                goto ipv6;
 148        default:
 149                break;
 150        }
 151
 152        flow->ip_proto = ip_proto;
 153        poff = proto_ports_offset(ip_proto);
 154        if (poff >= 0) {
 155                __be32 *ports, _ports;
 156
 157                ports = skb_header_pointer(skb, nhoff + poff,
 158                                           sizeof(_ports), &_ports);
 159                if (ports)
 160                        flow->ports = *ports;
 161        }
 162
 163        flow->thoff = (u16) nhoff;
 164
 165        return true;
 166}
 167EXPORT_SYMBOL(skb_flow_dissect);
 168
 169static u32 hashrnd __read_mostly;
 170
 171/*
 172 * __skb_get_rxhash: calculate a flow hash based on src/dst addresses
 173 * and src/dst port numbers.  Sets rxhash in skb to non-zero hash value
 174 * on success, zero indicates no valid hash.  Also, sets l4_rxhash in skb
 175 * if hash is a canonical 4-tuple hash over transport ports.
 176 */
 177void __skb_get_rxhash(struct sk_buff *skb)
 178{
 179        struct flow_keys keys;
 180        u32 hash;
 181
 182        if (!skb_flow_dissect(skb, &keys))
 183                return;
 184
 185        if (keys.ports)
 186                skb->l4_rxhash = 1;
 187
 188        /* get a consistent hash (same value on both flow directions) */
 189        if (((__force u32)keys.dst < (__force u32)keys.src) ||
 190            (((__force u32)keys.dst == (__force u32)keys.src) &&
 191             ((__force u16)keys.port16[1] < (__force u16)keys.port16[0]))) {
 192                swap(keys.dst, keys.src);
 193                swap(keys.port16[0], keys.port16[1]);
 194        }
 195
 196        hash = jhash_3words((__force u32)keys.dst,
 197                            (__force u32)keys.src,
 198                            (__force u32)keys.ports, hashrnd);
 199        if (!hash)
 200                hash = 1;
 201
 202        skb->rxhash = hash;
 203}
 204EXPORT_SYMBOL(__skb_get_rxhash);
 205
 206/*
 207 * Returns a Tx hash based on the given packet descriptor a Tx queues' number
 208 * to be used as a distribution range.
 209 */
 210u16 __skb_tx_hash(const struct net_device *dev, const struct sk_buff *skb,
 211                  unsigned int num_tx_queues)
 212{
 213        u32 hash;
 214        u16 qoffset = 0;
 215        u16 qcount = num_tx_queues;
 216
 217        if (skb_rx_queue_recorded(skb)) {
 218                hash = skb_get_rx_queue(skb);
 219                while (unlikely(hash >= num_tx_queues))
 220                        hash -= num_tx_queues;
 221                return hash;
 222        }
 223
 224        if (dev->num_tc) {
 225                u8 tc = netdev_get_prio_tc_map(dev, skb->priority);
 226                qoffset = dev->tc_to_txq[tc].offset;
 227                qcount = dev->tc_to_txq[tc].count;
 228        }
 229
 230        if (skb->sk && skb->sk->sk_hash)
 231                hash = skb->sk->sk_hash;
 232        else
 233                hash = (__force u16) skb->protocol;
 234        hash = jhash_1word(hash, hashrnd);
 235
 236        return (u16) (((u64) hash * qcount) >> 32) + qoffset;
 237}
 238EXPORT_SYMBOL(__skb_tx_hash);
 239
 240/* __skb_get_poff() returns the offset to the payload as far as it could
 241 * be dissected. The main user is currently BPF, so that we can dynamically
 242 * truncate packets without needing to push actual payload to the user
 243 * space and can analyze headers only, instead.
 244 */
 245u32 __skb_get_poff(const struct sk_buff *skb)
 246{
 247        struct flow_keys keys;
 248        u32 poff = 0;
 249
 250        if (!skb_flow_dissect(skb, &keys))
 251                return 0;
 252
 253        poff += keys.thoff;
 254        switch (keys.ip_proto) {
 255        case IPPROTO_TCP: {
 256                const struct tcphdr *tcph;
 257                struct tcphdr _tcph;
 258
 259                tcph = skb_header_pointer(skb, poff, sizeof(_tcph), &_tcph);
 260                if (!tcph)
 261                        return poff;
 262
 263                poff += max_t(u32, sizeof(struct tcphdr), tcph->doff * 4);
 264                break;
 265        }
 266        case IPPROTO_UDP:
 267        case IPPROTO_UDPLITE:
 268                poff += sizeof(struct udphdr);
 269                break;
 270        /* For the rest, we do not really care about header
 271         * extensions at this point for now.
 272         */
 273        case IPPROTO_ICMP:
 274                poff += sizeof(struct icmphdr);
 275                break;
 276        case IPPROTO_ICMPV6:
 277                poff += sizeof(struct icmp6hdr);
 278                break;
 279        case IPPROTO_IGMP:
 280                poff += sizeof(struct igmphdr);
 281                break;
 282        case IPPROTO_DCCP:
 283                poff += sizeof(struct dccp_hdr);
 284                break;
 285        case IPPROTO_SCTP:
 286                poff += sizeof(struct sctphdr);
 287                break;
 288        }
 289
 290        return poff;
 291}
 292
 293static inline u16 dev_cap_txqueue(struct net_device *dev, u16 queue_index)
 294{
 295        if (unlikely(queue_index >= dev->real_num_tx_queues)) {
 296                net_warn_ratelimited("%s selects TX queue %d, but real number of TX queues is %d\n",
 297                                     dev->name, queue_index,
 298                                     dev->real_num_tx_queues);
 299                return 0;
 300        }
 301        return queue_index;
 302}
 303
 304static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
 305{
 306#ifdef CONFIG_XPS
 307        struct xps_dev_maps *dev_maps;
 308        struct xps_map *map;
 309        int queue_index = -1;
 310
 311        rcu_read_lock();
 312        dev_maps = rcu_dereference(dev->xps_maps);
 313        if (dev_maps) {
 314                map = rcu_dereference(
 315                    dev_maps->cpu_map[raw_smp_processor_id()]);
 316                if (map) {
 317                        if (map->len == 1)
 318                                queue_index = map->queues[0];
 319                        else {
 320                                u32 hash;
 321                                if (skb->sk && skb->sk->sk_hash)
 322                                        hash = skb->sk->sk_hash;
 323                                else
 324                                        hash = (__force u16) skb->protocol ^
 325                                            skb->rxhash;
 326                                hash = jhash_1word(hash, hashrnd);
 327                                queue_index = map->queues[
 328                                    ((u64)hash * map->len) >> 32];
 329                        }
 330                        if (unlikely(queue_index >= dev->real_num_tx_queues))
 331                                queue_index = -1;
 332                }
 333        }
 334        rcu_read_unlock();
 335
 336        return queue_index;
 337#else
 338        return -1;
 339#endif
 340}
 341
 342u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb)
 343{
 344        struct sock *sk = skb->sk;
 345        int queue_index = sk_tx_queue_get(sk);
 346
 347        if (queue_index < 0 || skb->ooo_okay ||
 348            queue_index >= dev->real_num_tx_queues) {
 349                int new_index = get_xps_queue(dev, skb);
 350                if (new_index < 0)
 351                        new_index = skb_tx_hash(dev, skb);
 352
 353                if (queue_index != new_index && sk &&
 354                    rcu_access_pointer(sk->sk_dst_cache))
 355                        sk_tx_queue_set(sk, new_index);
 356
 357                queue_index = new_index;
 358        }
 359
 360        return queue_index;
 361}
 362EXPORT_SYMBOL(__netdev_pick_tx);
 363
 364struct netdev_queue *netdev_pick_tx(struct net_device *dev,
 365                                    struct sk_buff *skb)
 366{
 367        int queue_index = 0;
 368
 369        if (dev->real_num_tx_queues != 1) {
 370                const struct net_device_ops *ops = dev->netdev_ops;
 371                if (ops->ndo_select_queue)
 372                        queue_index = ops->ndo_select_queue(dev, skb);
 373                else
 374                        queue_index = __netdev_pick_tx(dev, skb);
 375                queue_index = dev_cap_txqueue(dev, queue_index);
 376        }
 377
 378        skb_set_queue_mapping(skb, queue_index);
 379        return netdev_get_tx_queue(dev, queue_index);
 380}
 381
 382static int __init initialize_hashrnd(void)
 383{
 384        get_random_bytes(&hashrnd, sizeof(hashrnd));
 385        return 0;
 386}
 387
 388late_initcall_sync(initialize_hashrnd);
 389