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                 /* skip the address processing if skb is NULL.  The assumption
 104                  * here is that if there is no skb we are not looking for flow
 105                  * info but lengths and protocols.
 106                  */
 107                 if (!skb)
 108                         break;
 109
 110                 iph_to_flow_copy_addrs(flow, iph);
 111                 break;
 112         }
 113         case htons(ETH_P_IPV6): {
 114                 const struct ipv6hdr *iph;
 115                 struct ipv6hdr _iph;
 116                 __be32 flow_label;
 117
 118 ipv6:
 119                 iph = __skb_header_pointer(skb, nhoff, sizeof(_iph), data, hlen, &_iph);
 120                 if (!iph)
 121                         return false;
 122
 123                 ip_proto = iph->nexthdr;
 124                 nhoff += sizeof(struct ipv6hdr);
 125
 126                 /* see comment above in IPv4 section */
 127                 if (!skb)
 128                         break;
 129
 130                 flow->src = (__force __be32)ipv6_addr_hash(&iph->saddr);
 131                 flow->dst = (__force __be32)ipv6_addr_hash(&iph->daddr);
 132
 133                 flow_label = ip6_flowlabel(iph);
 134                 if (flow_label) {
 135                         /* Awesome, IPv6 packet has a flow label so we can
 136                          * use that to represent the ports without any
 137                          * further dissection.
 138                          */
 139                         flow->n_proto = proto;
 140                         flow->ip_proto = ip_proto;
 141                         flow->ports = flow_label;
 142                         flow->thoff = (u16)nhoff;
 143
 144                         return true;
 145                 }
 146
 147                 break;
 148         }
 149         case htons(ETH_P_8021AD):
 150         case htons(ETH_P_8021Q): {
 151                 const struct vlan_hdr *vlan;
 152                 struct vlan_hdr _vlan;
 153
 154                 vlan = __skb_header_pointer(skb, nhoff, sizeof(_vlan), data, hlen, &_vlan);
 155                 if (!vlan)
 156                         return false;
 157
 158                 proto = vlan->h_vlan_encapsulated_proto;
 159                 nhoff += sizeof(*vlan);
 160                 goto again;
 161         }
 162         case htons(ETH_P_PPP_SES): {
 163                 struct {
 164                         struct pppoe_hdr hdr;
 165                         __be16 proto;
 166                 } *hdr, _hdr;
 167                 hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);
 168                 if (!hdr)
 169                         return false;
 170                 proto = hdr->proto;
 171                 nhoff += PPPOE_SES_HLEN;
 172                 switch (proto) {
 173                 case htons(PPP_IP):
 174                         goto ip;
 175                 case htons(PPP_IPV6):
 176                         goto ipv6;
 177                 default:
 178                         return false;
 179                 }
 180         }
 181         case htons(ETH_P_FCOE):
 182                 flow->thoff = (u16)(nhoff + FCOE_HEADER_LEN);
 183                 /* fall through */
 184         default:
 185                 return false;
 186         }
 187
 188         switch (ip_proto) {
 189         case IPPROTO_GRE: {
 190                 struct gre_hdr {
 191                         __be16 flags;
 192                         __be16 proto;
 193                 } *hdr, _hdr;
 194
 195                 hdr = __skb_header_pointer(skb, nhoff, sizeof(_hdr), data, hlen, &_hdr);
 196                 if (!hdr)
 197                         return false;
 198                 /*
 199                  * Only look inside GRE if version zero and no
 200                  * routing
 201                  */
 202                 if (!(hdr->flags & (GRE_VERSION|GRE_ROUTING))) {
 203                         proto = hdr->proto;
 204                         nhoff += 4;
 205                         if (hdr->flags & GRE_CSUM)
 206                                 nhoff += 4;
 207                         if (hdr->flags & GRE_KEY)
 208                                 nhoff += 4;
 209                         if (hdr->flags & GRE_SEQ)
 210                                 nhoff += 4;
 211                         if (proto == htons(ETH_P_TEB)) {
 212                                 const struct ethhdr *eth;
 213                                 struct ethhdr _eth;
 214
 215                                 eth = __skb_header_pointer(skb, nhoff,
 216                                                            sizeof(_eth),
 217                                                            data, hlen, &_eth);
 218                                 if (!eth)
 219                                         return false;
 220                                 proto = eth->h_proto;
 221                                 nhoff += sizeof(*eth);
 222                         }
 223                         goto again;
 224                 }
 225                 break;
 226         }
 227         case IPPROTO_IPIP:
 228                 proto = htons(ETH_P_IP);
 229                 goto ip;
 230         case IPPROTO_IPV6:
 231                 proto = htons(ETH_P_IPV6);
 232                 goto ipv6;
 233         default:
 234                 break;
 235         }
 236
 237         flow->n_proto = proto;
 238         flow->ip_proto = ip_proto;
 239         flow->thoff = (u16) nhoff;
 240
 241         /* unless skb is set we don't need to record port info */
 242         if (skb)
 243                 flow->ports = __skb_flow_get_ports(skb, nhoff, ip_proto,
 244                                                    data, hlen);
 245
 246         return true;
 247 }
 248 EXPORT_SYMBOL(__skb_flow_dissect);
 249
 250 static u32 hashrnd __read_mostly;
 251 static __always_inline void __flow_hash_secret_init(void)
 252 {
 253         net_get_random_once(&hashrnd, sizeof(hashrnd));
 254 }
 255
 256 static __always_inline u32 __flow_hash_3words(u32 a, u32 b, u32 c)
 257 {
 258         __flow_hash_secret_init();
 259         return jhash_3words(a, b, c, hashrnd);
 260 }
 261
 262 static inline u32 __flow_hash_from_keys(struct flow_keys *keys)
 263 {
 264         u32 hash;
 265
 266         /* get a consistent hash (same value on both flow directions) */
 267         if (((__force u32)keys->dst < (__force u32)keys->src) ||
 268             (((__force u32)keys->dst == (__force u32)keys->src) &&
 269              ((__force u16)keys->port16[1] < (__force u16)keys->port16[0]))) {
 270                 swap(keys->dst, keys->src);
 271                 swap(keys->port16[0], keys->port16[1]);
 272         }
 273
 274         hash = __flow_hash_3words((__force u32)keys->dst,
 275                                   (__force u32)keys->src,
 276                                   (__force u32)keys->ports);
 277         if (!hash)
 278                 hash = 1;
 279
 280         return hash;
 281 }
 282
 283 u32 flow_hash_from_keys(struct flow_keys *keys)
 284 {
 285         return __flow_hash_from_keys(keys);
 286 }
 287 EXPORT_SYMBOL(flow_hash_from_keys);
 288
 289 /*
 290  * __skb_get_hash: calculate a flow hash based on src/dst addresses
 291  * and src/dst port numbers.  Sets hash in skb to non-zero hash value
 292  * on success, zero indicates no valid hash.  Also, sets l4_hash in skb
 293  * if hash is a canonical 4-tuple hash over transport ports.
 294  */
 295 void __skb_get_hash(struct sk_buff *skb)
 296 {
 297         struct flow_keys keys;
 298
 299         if (!skb_flow_dissect(skb, &keys))
 300                 return;
 301
 302         if (keys.ports)
 303                 skb->l4_hash = 1;
 304
 305         skb->sw_hash = 1;
 306
 307         skb->hash = __flow_hash_from_keys(&keys);
 308 }
 309 EXPORT_SYMBOL(__skb_get_hash);
 310
 311 /*
 312  * Returns a Tx hash based on the given packet descriptor a Tx queues' number
 313  * to be used as a distribution range.
 314  */
 315 u16 __skb_tx_hash(const struct net_device *dev, struct sk_buff *skb,
 316                   unsigned int num_tx_queues)
 317 {
 318         u32 hash;
 319         u16 qoffset = 0;
 320         u16 qcount = num_tx_queues;
 321
 322         if (skb_rx_queue_recorded(skb)) {
 323                 hash = skb_get_rx_queue(skb);
 324                 while (unlikely(hash >= num_tx_queues))
 325                         hash -= num_tx_queues;
 326                 return hash;
 327         }
 328
 329         if (dev->num_tc) {
 330                 u8 tc = netdev_get_prio_tc_map(dev, skb->priority);
 331                 qoffset = dev->tc_to_txq[tc].offset;
 332                 qcount = dev->tc_to_txq[tc].count;
 333         }
 334
 335         return (u16) reciprocal_scale(skb_get_hash(skb), qcount) + qoffset;
 336 }
 337 EXPORT_SYMBOL(__skb_tx_hash);
 338
 339 u32 __skb_get_poff(const struct sk_buff *skb, void *data,
 340                    const struct flow_keys *keys, int hlen)
 341 {
 342         u32 poff = keys->thoff;
 343
 344         switch (keys->ip_proto) {
 345         case IPPROTO_TCP: {
 346                 /* access doff as u8 to avoid unaligned access */
 347                 const u8 *doff;
 348                 u8 _doff;
 349
 350                 doff = __skb_header_pointer(skb, poff + 12, sizeof(_doff),
 351                                             data, hlen, &_doff);
 352                 if (!doff)
 353                         return poff;
 354
 355                 poff += max_t(u32, sizeof(struct tcphdr), (*doff & 0xF0) >> 2);
 356                 break;
 357         }
 358         case IPPROTO_UDP:
 359         case IPPROTO_UDPLITE:
 360                 poff += sizeof(struct udphdr);
 361                 break;
 362         /* For the rest, we do not really care about header
 363          * extensions at this point for now.
 364          */
 365         case IPPROTO_ICMP:
 366                 poff += sizeof(struct icmphdr);
 367                 break;
 368         case IPPROTO_ICMPV6:
 369                 poff += sizeof(struct icmp6hdr);
 370                 break;
 371         case IPPROTO_IGMP:
 372                 poff += sizeof(struct igmphdr);
 373                 break;
 374         case IPPROTO_DCCP:
 375                 poff += sizeof(struct dccp_hdr);
 376                 break;
 377         case IPPROTO_SCTP:
 378                 poff += sizeof(struct sctphdr);
 379                 break;
 380         }
 381
 382         return poff;
 383 }
 384
 385 /* skb_get_poff() returns the offset to the payload as far as it could
 386  * be dissected. The main user is currently BPF, so that we can dynamically
 387  * truncate packets without needing to push actual payload to the user
 388  * space and can analyze headers only, instead.
 389  */
 390 u32 skb_get_poff(const struct sk_buff *skb)
 391 {
 392         struct flow_keys keys;
 393
 394         if (!skb_flow_dissect(skb, &keys))
 395                 return 0;
 396
 397         return __skb_get_poff(skb, skb->data, &keys, skb_headlen(skb));
 398 }
 399
 400 static inline int get_xps_queue(struct net_device *dev, struct sk_buff *skb)
 401 {
 402 #ifdef CONFIG_XPS
 403         struct xps_dev_maps *dev_maps;
 404         struct xps_map *map;
 405         int queue_index = -1;
 406
 407         rcu_read_lock();
 408         dev_maps = rcu_dereference(dev->xps_maps);
 409         if (dev_maps) {
 410                 map = rcu_dereference(
 411                     dev_maps->cpu_map[raw_smp_processor_id()]);
 412                 if (map) {
 413                         if (map->len == 1)
 414                                 queue_index = map->queues[0];
 415                         else
 416                                 queue_index = map->queues[reciprocal_scale(skb_get_hash(skb),
 417                                                                            map->len)];
 418                         if (unlikely(queue_index >= dev->real_num_tx_queues))
 419                                 queue_index = -1;
 420                 }
 421         }
 422         rcu_read_unlock();
 423
 424         return queue_index;
 425 #else
 426         return -1;
 427 #endif
 428 }
 429
 430 static u16 __netdev_pick_tx(struct net_device *dev, struct sk_buff *skb)
 431 {
 432         struct sock *sk = skb->sk;
 433         int queue_index = sk_tx_queue_get(sk);
 434
 435         if (queue_index < 0 || skb->ooo_okay ||
 436             queue_index >= dev->real_num_tx_queues) {
 437                 int new_index = get_xps_queue(dev, skb);
 438                 if (new_index < 0)
 439                         new_index = skb_tx_hash(dev, skb);
 440
 441                 if (queue_index != new_index && sk &&
 442                     rcu_access_pointer(sk->sk_dst_cache))
 443                         sk_tx_queue_set(sk, new_index);
 444
 445                 queue_index = new_index;
 446         }
 447
 448         return queue_index;
 449 }
 450
 451 struct netdev_queue *netdev_pick_tx(struct net_device *dev,
 452                                     struct sk_buff *skb,
 453                                     void *accel_priv)
 454 {
 455         int queue_index = 0;
 456
 457         if (dev->real_num_tx_queues != 1) {
 458                 const struct net_device_ops *ops = dev->netdev_ops;
 459                 if (ops->ndo_select_queue)
 460                         queue_index = ops->ndo_select_queue(dev, skb, accel_priv,
 461                                                             __netdev_pick_tx);
 462                 else
 463                         queue_index = __netdev_pick_tx(dev, skb);
 464
 465                 if (!accel_priv)
 466                         queue_index = netdev_cap_txqueue(dev, queue_index);
 467         }
 468
 469         skb_set_queue_mapping(skb, queue_index);
 470         return netdev_get_tx_queue(dev, queue_index);
 471 }