net/core/flow_dissector.c

   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 #include <scsi/fc/fc_fcoe.h>
  17
  18 /* copy saddr & daddr, possibly using 64bit load/store
  19  * Equivalent to :      flow->src = iph->saddr;
  20  *                      flow->dst = iph->daddr;
  21  */
  22 static void iph_to_flow_copy_addrs(struct flow_keys *flow, const struct iphdr *iph)
  23 {
  24         BUILD_BUG_ON(offsetof(typeof(*flow), dst) !=
  25                      offsetof(typeof(*flow), src) + sizeof(flow->src));
  26         memcpy(&flow->src, &iph->saddr, sizeof(flow->src) + sizeof(flow->dst));
  27 }
  28
  29 /**
  30  * __skb_flow_get_ports - extract the upper layer ports and return them
  31  * @skb: sk_buff to extract the ports from
  32  * @thoff: transport header offset
  33  * @ip_proto: protocol for which to get port offset
  34  * @data: raw buffer pointer to the packet, if NULL use skb->data
  35  * @hlen: packet header length, if @data is NULL use skb_headlen(skb)
  36  *
  37  * The function will try to retrieve the ports at offset thoff + poff where poff
  38  * is the protocol port offset returned from proto_ports_offset
  39  */
  40 __be32 __skb_flow_get_ports(const struct sk_buff *skb, int thoff, u8 ip_proto,
  41                             void *data, int hlen)
  42 {
  43         int poff = proto_ports_offset(ip_proto);
  44
  45         if (!data) {
  46                 data = skb->data;
  47                 hlen = skb_headlen(skb);
  48         }
  49
  50         if (poff >= 0) {
  51                 __be32 *ports, _ports;
  52
  53                 ports = __skb_header_pointer(skb, thoff + poff,
  54                                              sizeof(_ports), data, hlen, &_ports);
  55                 if (ports)
  56                         return *ports;
  57         }
  58
  59         return 0;
  60 }
  61 EXPORT_SYMBOL(__skb_flow_get_ports);
  62
  63 /**
  64  * __skb_flow_dissect - extract the flow_keys struct and return it
  65  * @skb: sk_buff to extract the flow from, can be NULL if the rest are specified
  66  * @data: raw buffer pointer to the packet, if NULL use skb->data
  67  * @proto: protocol for which to get the flow, if @data is NULL use skb->protocol
  68  * @nhoff: network header offset, if @data is NULL use skb_network_offset(skb)
  69  * @hlen: packet header length, if @data is NULL use skb_headlen(skb)
  70  *
  71  * The function will try to retrieve the struct flow_keys from either the skbuff
  72  * or a raw buffer specified by the rest parameters
  73  */
  74 bool __skb_flow_dissect(const struct sk_buff *skb, struct flow_keys *flow,
  75                         void *data, __be16 proto, int nhoff, int hlen)
  76 {
  77         u8 ip_proto;
  78
  79         if (!data) {
  80                 data = skb->data;
  81                 proto = skb->protocol;
  82                 nhoff = skb_network_offset(skb);
  83                 hlen = skb_headlen(skb);
  84         }
  85
  86         memset(flow, 0, sizeof(*flow));
  87
  88 again:
  89         switch (proto) {
  90         case htons(ETH_P_IP): {
  91                 const struct iphdr *iph;
  92                 struct iphdr _iph;
  93 ip:
  94                 iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph);
  95                 if (!iph || iph->ihl < 5)
  96                         return false;
  97                 nhoff += iph->ihl * 4;
  98
  99                 ip_proto = iph->protocol;
 100                 if (ip_is_fragment(iph))
 101                         ip_proto = 0;
 102
 103                 iph_to_flow_copy_addrs(flow, iph);
 104                 break;
 105         }
 106         case htons(ETH_P_IPV6): {
 107                 const struct ipv6hdr *iph;
 108                 struct ipv6hdr _iph;
 109                 __be32 flow_label;
 110
 111 ipv6:
 112                 iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph);
 113                 if (!iph)
 114                         return false;
 115
 116                 ip_proto = iph->nexthdr;
 117                 flow->src = (__force __be32)ipv6_addr_hash(&iph->saddr);
 118                 flow->dst = (__force __be32)ipv6_addr_hash(&iph->daddr);
 119                 nhoff += sizeof(struct ipv6hdr);
 120
 121                 /* skip the flow label processing if skb is NULL.  The
 122                  * assumption here is that if there is no skb we are not
 123                  * looking for flow info as much as we are length.
 124                  */
 125                 if (!skb)
 126                         break;
 127
 128                 flow_label = ip6_flowlabel(iph);
 129                 if (flow_label) {
 130                         /* Awesome, IPv6 packet has a flow label so we can
 131                          * use that to represent the ports without any
 132                          * further dissection.
 133                          */
 134                         flow->n_proto = proto;
 135                         flow->ip_proto = ip_proto;
 136                         flow->ports = flow_label;
 137                         flow->thoff = (u16)nhoff;
 138
 139                         return true;
 140                 }
 141
 142                 break;
 143         }
 144         case htons(ETH_P_8021AD):
 145         case htons(ETH_P_8021Q): {
 146                 const struct vlan_hdr *vlan;
 147                 struct vlan_hdr _vlan;
 148
 149                 vlan = __skb_header_pointer(skb, nhoff, sizeof(_vlan), data, hlen, &_vlan);
 150                 if (!vlan)
 151                         return false;
 152
 153                 proto = vlan->h_vlan_encapsulated_proto;
 154                 nhoff += sizeof(*vlan);
 155                 goto again;
 156         }
 157         case htons(ETH_P_PPP_SES): {
 158                 struct {
 159                         struct pppoe_hdr hdr;
 160                         __be16 proto;
 161                 } *hdr, _hdr;
 162                 hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);
 163                 if (!hdr)
 164                         return false;
 165                 proto = hdr->proto;
 166                 nhoff += PPPOE_SES_HLEN;
 167                 switch (proto) {
 168                 case htons(PPP_IP):
 169                         goto ip;
 170                 case htons(PPP_IPV6):
 171                         goto ipv6;
 172                 default:
 173                         return false;
 174                 }
 175         }
 176         case htons(ETH_P_FCOE):
 177                 flow->thoff = (u16)(nhoff + FCOE_HEADER_LEN);
 178                 /* fall through */
 179         default:
 180                 return false;
 181         }
 182
 183         switch (ip_proto) {
 184         case IPPROTO_GRE: {
 185                 struct gre_hdr {
 186                         __be16 flags;
 187                         __be16 proto;
 188                 } *hdr, _hdr;
 189
 190                 hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);
 191                 if (!hdr)
 192                         return false;
 193                 /*
 194                  * Only look inside GRE if version zero and no
 195                  * routing
 196                  */
 197                 if (!(hdr->flags & (GRE_VERSION|GRE_ROUTING))) {
 198                         proto = hdr->proto;
 199                         nhoff += 4;
 200                         if (hdr->flags & GRE_CSUM)
 201                                 nhoff += 4;
 202                         if (hdr->flags & GRE_KEY)
 203                                 nhoff += 4;
 204                         if (hdr->flags & GRE_SEQ)
 205                                 nhoff += 4;
 206                         if (proto == htons(ETH_P_TEB)) {
 207                                 const struct ethhdr *eth;
 208                                 struct ethhdr _eth;
 209
 210                                 eth = __skb_header_pointer(skb, nhoff,
 211                                                            sizeof(_eth),
 212                                                            data, hlen, &_eth);
 213                                 if (!eth)
 214                                         return false;
 215                                 proto = eth->h_proto;
 216                                 nhoff += sizeof(*eth);
 217                         }
 218                         goto again;
 219                 }
 220                 break;
 221         }
 222         case IPPROTO_IPIP:
 223                 proto = htons(ETH_P_IP);
 224                 goto ip;
 225         case IPPROTO_IPV6:
 226                 proto = htons(ETH_P_IPV6);
 227                 goto ipv6;
 228         default:
 229                 break;
 230         }
 231
 232         flow->n_proto = proto;
 233         flow->ip_proto = ip_proto;
 234         flow->ports = __skb_flow_get_ports(skb, nhoff, ip_proto, data, hlen);
 235         flow->thoff = (u16) nhoff;
 236
 237         return true;
 238 }
 239 EXPORT_SYMBOL(__skb_flow_dissect);
 240
 241 static u32 hashrnd __read_mostly;
 242 static __always_inline void __flow_hash_secret_init(void)
 243 {
 244         net_get_random_once(&hashrnd, sizeof(hashrnd));
 245 }
 246
 247 static __always_inline u32 __flow_hash_3words(u32 a, u32 b, u32 c)
 248 {
 249         __flow_hash_secret_init();
 250         return jhash_3words(a, b, c, hashrnd);
 251 }
 252
 253 static inline u32 __flow_hash_from_keys(struct flow_keys *keys)
 254 {
 255         u32 hash;
 256
 257         /* get a consistent hash (same value on both flow directions) */
 258         if (((__force u32)keys->dst < (__force u32)keys->src) ||
 259             (((__force u32)keys->dst == (__force u32)keys->src) &&
 260              ((__force u16)keys->port16[1] < (__force u16)keys->port16[0]))) {
 261                 swap(keys->dst, keys->src);
 262                 swap(keys->port16[0], keys->port16[1]);
 263         }
 264
 265         hash = __flow_hash_3words((__force u32)keys->dst,
 266                                   (__force u32)keys->src,
 267                                   (__force u32)keys->ports);
 268         if (!hash)
 269                 hash = 1;
 270
 271         return hash;
 272 }
 273
 274 u32 flow_hash_from_keys(struct flow_keys *keys)
 275 {
 276         return __flow_hash_from_keys(keys);
 277 }
 278 EXPORT_SYMBOL(flow_hash_from_keys);
 279
 280 /*
 281  * __skb_get_hash: calculate a flow hash based on src/dst addresses
 282  * and src/dst port numbers.  Sets hash in skb to non-zero hash value
 283  * on success, zero indicates no valid hash.  Also, sets l4_hash in skb
 284  * if hash is a canonical 4-tuple hash over transport ports.
 285  */
 286 void __skb_get_hash(struct sk_buff *skb)
 287 {
 288         struct flow_keys keys;
 289
 290         if (!skb_flow_dissect(skb, &keys))
 291                 return;
 292
 293         if (keys.ports)
 294                 skb->l4_hash = 1;
 295
 296         skb->sw_hash = 1;
 297
 298         skb->hash = __flow_hash_from_keys(&keys);
 299 }
 300 EXPORT_SYMBOL(__skb_get_hash);
 301
 302 /*
 303  * Returns a Tx hash based on the given packet descriptor a Tx queues' number
 304  * to be used as a distribution range.
 305  */
 306 u16 __skb_tx_hash(const struct net_device *dev, struct sk_buff *skb,
 307                   unsigned int num_tx_queues)
 308 {
 309         u32 hash;
 310         u16 qoffset = 0;
 311         u16 qcount = num_tx_queues;
 312
 313         if (skb_rx_queue_recorded(skb)) {
 314                 hash = skb_get_rx_queue(skb);
 315                 while (unlikely(hash >= num_tx_queues))
 316                         hash -= num_tx_queues;
 317                 return hash;
 318         }
 319
 320         if (dev->num_tc) {
 321                 u8 tc = netdev_get_prio_tc_map(dev, skb->priority);
 322                 qoffset = dev->tc_to_txq[tc].offset;
 323                 qcount = dev->tc_to_txq[tc].count;
 324         }
 325
 326         return (u16) reciprocal_scale(skb_get_hash(skb), qcount) + qoffset;
 327 }
 328 EXPORT_SYMBOL(__skb_tx_hash);
 329
 330 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
 331                    const struct flow_keys *keys, int hlen)
 332 {
 333         u32 poff = keys->thoff;
 334
 335         switch (keys->ip_proto) {
 336         case IPPROTO_TCP: {
 337                 const struct tcphdr *tcph;
 338                 struct tcphdr _tcph;
 339
 340                 tcph = __skb_header_pointer(skb, poff, sizeof(_tcph),
 341                                             data, hlen, &_tcph);
 342                 if (!tcph)
 343                         return poff;
 344
 345                 poff += max_t(u32, sizeof(struct tcphdr), tcph->doff * 4);
 346                 break;
 347         }
 348         case IPPROTO_UDP:
 349         case IPPROTO_UDPLITE:
 350                 poff += sizeof(struct udphdr);
 351                 break;
 352         /* For the rest, we do not really care about header
 353          * extensions at this point for now.
 354          */
 355         case IPPROTO_ICMP:
 356                 poff += sizeof(struct icmphdr);
 357                 break;
 358         case IPPROTO_ICMPV6:
 359                 poff += sizeof(struct icmp6hdr);
 360                 break;
 361         case IPPROTO_IGMP:
 362                 poff += sizeof(struct igmphdr);
 363                 break;
 364         case IPPROTO_DCCP:
 365                 poff += sizeof(struct dccp_hdr);
 366                 break;
 367         case IPPROTO_SCTP:
 368                 poff += sizeof(struct sctphdr);
 369                 break;
 370         }
 371
 372         return poff;
 373 }
 374
 375 /* skb_get_poff() returns the offset to the payload as far as it could
 376  * be dissected. The main user is currently BPF, so that we can dynamically
 377  * truncate packets without needing to push actual payload to the user
 378  * space and can analyze headers only, instead.
 379  */
 380 u32 skb_get_poff(const struct sk_buff *skb)
 381 {
 382         struct flow_keys keys;
 383
 384         if (!skb_flow_dissect(skb, &keys))
 385                 return 0;
 386
 387         return __skb_get_poff(skb, skb->data, &keys, skb_headlen(skb));
 388 }
 389
 390 static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
 391 {
 392 #ifdef CONFIG_XPS
 393         struct xps_dev_maps *dev_maps;
 394         struct xps_map *map;
 395         int queue_index = -1;
 396
 397         rcu_read_lock();
 398         dev_maps = rcu_dereference(dev->xps_maps);
 399         if (dev_maps) {
 400                 map = rcu_dereference(
 401                     dev_maps->cpu_map[raw_smp_processor_id()]);
 402                 if (map) {
 403                         if (map->len == 1)
 404                                 queue_index = map->queues[0];
 405                         else
 406                                 queue_index = map->queues[reciprocal_scale(skb_get_hash(skb),
 407                                                                            map->len)];
 408                         if (unlikely(queue_index >= dev->real_num_tx_queues))
 409                                 queue_index = -1;
 410                 }
 411         }
 412         rcu_read_unlock();
 413
 414         return queue_index;
 415 #else
 416         return -1;
 417 #endif
 418 }
 419
 420 static u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb)
 421 {
 422         struct sock *sk = skb->sk;
 423         int queue_index = sk_tx_queue_get(sk);
 424
 425         if (queue_index < 0 || skb->ooo_okay ||
 426             queue_index >= dev->real_num_tx_queues) {
 427                 int new_index = get_xps_queue(dev, skb);
 428                 if (new_index < 0)
 429                         new_index = skb_tx_hash(dev, skb);
 430
 431                 if (queue_index != new_index && sk &&
 432                     rcu_access_pointer(sk->sk_dst_cache))
 433                         sk_tx_queue_set(sk, new_index);
 434
 435                 queue_index = new_index;
 436         }
 437
 438         return queue_index;
 439 }
 440
 441 struct netdev_queue *netdev_pick_tx(struct net_device *dev,
 442                                     struct sk_buff *skb,
 443                                     void *accel_priv)
 444 {
 445         int queue_index = 0;
 446
 447         if (dev->real_num_tx_queues != 1) {
 448                 const struct net_device_ops *ops = dev->netdev_ops;
 449                 if (ops->ndo_select_queue)
 450                         queue_index = ops->ndo_select_queue(dev, skb, accel_priv,
 451                                                             __netdev_pick_tx);
 452                 else
 453                         queue_index = __netdev_pick_tx(dev, skb);
 454
 455                 if (!accel_priv)
 456                         queue_index = netdev_cap_txqueue(dev, queue_index);
 457         }
 458
 459         skb_set_queue_mapping(skb, queue_index);
 460         return netdev_get_tx_queue(dev, queue_index);
 461 }