datapath/flow.c

   1 /*
   2  * Distributed under the terms of the GNU GPL version 2.
   3  * Copyright (c) 2007, 2008 The Board of Trustees of The Leland
   4  * Stanford Junior University
   5  */
   6
   7 #include "flow.h"
   8 #include <linux/netdevice.h>
   9 #include <linux/etherdevice.h>
  10 #include <linux/if_ether.h>
  11 #include <linux/if_vlan.h>
  12 #include <net/llc_pdu.h>
  13 #include <linux/ip.h>
  14 #include <linux/jiffies.h>
  15 #include <linux/kernel.h>
  16 #include <linux/module.h>
  17 #include <linux/tcp.h>
  18 #include <linux/udp.h>
  19 #include <linux/in.h>
  20 #include <linux/rcupdate.h>
  21 #include <net/ip.h>
  22
  23 #include "openflow.h"
  24 #include "compat.h"
  25 #include "snap.h"
  26
  27 struct kmem_cache *flow_cache;
  28
  29 /* Internal function used to compare fields in flow. */
  30 static inline
  31 int flow_fields_match(const struct sw_flow_key *a, const struct sw_flow_key *b,
  32                       uint32_t w, uint32_t src_mask, uint32_t dst_mask)
  33 {
  34         return ((w & OFPFW_IN_PORT || a->in_port == b->in_port)
  35                 && (w & OFPFW_DL_VLAN || a->dl_vlan == b->dl_vlan)
  36                 && (w & OFPFW_DL_SRC || !memcmp(a->dl_src, b->dl_src, ETH_ALEN))
  37                 && (w & OFPFW_DL_DST || !memcmp(a->dl_dst, b->dl_dst, ETH_ALEN))
  38                 && (w & OFPFW_DL_TYPE || a->dl_type == b->dl_type)
  39                 && !((a->nw_src ^ b->nw_src) & src_mask)
  40                 && !((a->nw_dst ^ b->nw_dst) & dst_mask)
  41                 && (w & OFPFW_NW_PROTO || a->nw_proto == b->nw_proto)
  42                 && (w & OFPFW_TP_SRC || a->tp_src == b->tp_src)
  43                 && (w & OFPFW_TP_DST || a->tp_dst == b->tp_dst));
  44 }
  45
  46 /* Returns nonzero if 'a' and 'b' match, that is, if their fields are equal
  47  * modulo wildcards in 'b', zero otherwise. */
  48 int flow_matches_1wild(const struct sw_flow_key *a,
  49                        const struct sw_flow_key *b)
  50 {
  51         return flow_fields_match(a, b, b->wildcards,
  52                                  b->nw_src_mask, b->nw_dst_mask);
  53 }
  54 EXPORT_SYMBOL(flow_matches_1wild);
  55
  56 /* Returns nonzero if 'a' and 'b' match, that is, if their fields are equal
  57  * modulo wildcards in 'a' or 'b', zero otherwise. */
  58 int flow_matches_2wild(const struct sw_flow_key *a,
  59                        const struct sw_flow_key *b)
  60 {
  61         return flow_fields_match(a, b,
  62                                  a->wildcards | b->wildcards,
  63                                  a->nw_src_mask & b->nw_src_mask,
  64                                  a->nw_dst_mask & b->nw_dst_mask);
  65 }
  66 EXPORT_SYMBOL(flow_matches_2wild);
  67
  68 /* Returns nonzero if 't' (the table entry's key) and 'd' (the key
  69  * describing the match) match, that is, if their fields are
  70  * equal modulo wildcards, zero otherwise.  If 'strict' is nonzero, the
  71  * wildcards must match in both 't_key' and 'd_key'.  Note that the
  72  * table's wildcards are ignored unless 'strict' is set. */
  73 int flow_matches_desc(const struct sw_flow_key *t, const struct sw_flow_key *d,
  74                 int strict)
  75 {
  76         if (strict && d->wildcards != t->wildcards)
  77                 return 0;
  78         return flow_matches_1wild(t, d);
  79 }
  80 EXPORT_SYMBOL(flow_matches_desc);
  81
  82 static uint32_t make_nw_mask(int n_wild_bits)
  83 {
  84         n_wild_bits &= (1u << OFPFW_NW_SRC_BITS) - 1;
  85         return n_wild_bits < 32 ? htonl(~((1u << n_wild_bits) - 1)) : 0;
  86 }
  87
  88 void flow_extract_match(struct sw_flow_key* to, const struct ofp_match* from)
  89 {
  90         to->wildcards = ntohl(from->wildcards) & OFPFW_ALL;
  91         to->pad = 0;
  92         to->in_port = from->in_port;
  93         to->dl_vlan = from->dl_vlan;
  94         memcpy(to->dl_src, from->dl_src, ETH_ALEN);
  95         memcpy(to->dl_dst, from->dl_dst, ETH_ALEN);
  96         to->dl_type = from->dl_type;
  97
  98         to->nw_src = to->nw_dst = to->nw_proto = 0;
  99         to->tp_src = to->tp_dst = 0;
 100
 101 #define OFPFW_TP (OFPFW_TP_SRC | OFPFW_TP_DST)
 102 #define OFPFW_NW (OFPFW_NW_SRC_MASK | OFPFW_NW_DST_MASK | OFPFW_NW_PROTO)
 103         if (to->wildcards & OFPFW_DL_TYPE) {
 104                 /* Can't sensibly match on network or transport headers if the
 105                  * data link type is unknown. */
 106                 to->wildcards |= OFPFW_NW | OFPFW_TP;
 107         } else if (from->dl_type == htons(ETH_P_IP)) {
 108                 to->nw_src   = from->nw_src;
 109                 to->nw_dst   = from->nw_dst;
 110                 to->nw_proto = from->nw_proto;
 111
 112                 if (to->wildcards & OFPFW_NW_PROTO) {
 113                         /* Can't sensibly match on transport headers if the
 114                          * network protocol is unknown. */
 115                         to->wildcards |= OFPFW_TP;
 116                 } else if (from->nw_proto == IPPROTO_TCP
 117                            || from->nw_proto == IPPROTO_UDP) {
 118                         to->tp_src = from->tp_src;
 119                         to->tp_dst = from->tp_dst;
 120                 } else {
 121                         /* Transport layer fields are undefined.  Mark them as
 122                          * exact-match to allow such flows to reside in
 123                          * table-hash, instead of falling into table-linear. */
 124                         to->wildcards &= ~OFPFW_TP;
 125                 }
 126         } else {
 127                 /* Network and transport layer fields are undefined.  Mark them
 128                  * as exact-match to allow such flows to reside in table-hash,
 129                  * instead of falling into table-linear. */
 130                 to->wildcards &= ~(OFPFW_NW | OFPFW_TP);
 131         }
 132
 133         /* We set these late because code above adjusts to->wildcards. */
 134         to->nw_src_mask = make_nw_mask(to->wildcards >> OFPFW_NW_SRC_SHIFT);
 135         to->nw_dst_mask = make_nw_mask(to->wildcards >> OFPFW_NW_DST_SHIFT);
 136 }
 137
 138 void flow_fill_match(struct ofp_match* to, const struct sw_flow_key* from)
 139 {
 140         to->wildcards = htonl(from->wildcards);
 141         to->in_port   = from->in_port;
 142         to->dl_vlan   = from->dl_vlan;
 143         memcpy(to->dl_src, from->dl_src, ETH_ALEN);
 144         memcpy(to->dl_dst, from->dl_dst, ETH_ALEN);
 145         to->dl_type   = from->dl_type;
 146         to->nw_src    = from->nw_src;
 147         to->nw_dst    = from->nw_dst;
 148         to->nw_proto  = from->nw_proto;
 149         to->tp_src    = from->tp_src;
 150         to->tp_dst    = from->tp_dst;
 151         to->pad       = 0;
 152 }
 153
 154 int flow_timeout(struct sw_flow *flow)
 155 {
 156         if (flow->idle_timeout != OFP_FLOW_PERMANENT
 157             && time_after(jiffies, flow->used + flow->idle_timeout * HZ))
 158                 return OFPER_IDLE_TIMEOUT;
 159         else if (flow->hard_timeout != OFP_FLOW_PERMANENT
 160                  && time_after(jiffies,
 161                                flow->init_time + flow->hard_timeout * HZ))
 162                 return OFPER_HARD_TIMEOUT;
 163         else
 164                 return -1;
 165 }
 166 EXPORT_SYMBOL(flow_timeout);
 167
 168 /* Allocates and returns a new flow with room for 'actions_len' actions,
 169  * using allocation flags 'flags'.  Returns the new flow or a null pointer
 170  * on failure. */
 171 struct sw_flow *flow_alloc(size_t actions_len, gfp_t flags)
 172 {
 173         struct sw_flow_actions *sfa;
 174         size_t size = sizeof *sfa + actions_len;
 175         struct sw_flow *flow = kmem_cache_alloc(flow_cache, flags);
 176         if (unlikely(!flow))
 177                 return NULL;
 178
 179         sfa = kmalloc(size, flags);
 180         if (unlikely(!sfa)) {
 181                 kmem_cache_free(flow_cache, flow);
 182                 return NULL;
 183         }
 184         sfa->actions_len = actions_len;
 185         flow->sf_acts = sfa;
 186
 187         return flow;
 188 }
 189
 190 /* Frees 'flow' immediately. */
 191 void flow_free(struct sw_flow *flow)
 192 {
 193         if (unlikely(!flow))
 194                 return;
 195         kfree(flow->sf_acts);
 196         kmem_cache_free(flow_cache, flow);
 197 }
 198 EXPORT_SYMBOL(flow_free);
 199
 200 /* RCU callback used by flow_deferred_free. */
 201 static void rcu_free_flow_callback(struct rcu_head *rcu)
 202 {
 203         struct sw_flow *flow = container_of(rcu, struct sw_flow, rcu);
 204         flow_free(flow);
 205 }
 206
 207 /* Schedules 'flow' to be freed after the next RCU grace period.
 208  * The caller must hold rcu_read_lock for this to be sensible. */
 209 void flow_deferred_free(struct sw_flow *flow)
 210 {
 211         call_rcu(&flow->rcu, rcu_free_flow_callback);
 212 }
 213 EXPORT_SYMBOL(flow_deferred_free);
 214
 215 /* RCU callback used by flow_deferred_free_acts. */
 216 static void rcu_free_acts_callback(struct rcu_head *rcu)
 217 {
 218         struct sw_flow_actions *sf_acts = container_of(rcu,
 219                         struct sw_flow_actions, rcu);
 220         kfree(sf_acts);
 221 }
 222
 223 /* Schedules 'sf_acts' to be freed after the next RCU grace period.
 224  * The caller must hold rcu_read_lock for this to be sensible. */
 225 void flow_deferred_free_acts(struct sw_flow_actions *sf_acts)
 226 {
 227         call_rcu(&sf_acts->rcu, rcu_free_acts_callback);
 228 }
 229 EXPORT_SYMBOL(flow_deferred_free_acts);
 230
 231 /* Copies 'actions' into a newly allocated structure for use by 'flow'
 232  * and safely frees the structure that defined the previous actions. */
 233 void flow_replace_acts(struct sw_flow *flow,
 234                 const struct ofp_action_header *actions, size_t actions_len)
 235 {
 236         struct sw_flow_actions *sfa;
 237         struct sw_flow_actions *orig_sfa = flow->sf_acts;
 238         size_t size = sizeof *sfa + actions_len;
 239
 240         sfa = kmalloc(size, GFP_ATOMIC);
 241         if (unlikely(!sfa))
 242                 return;
 243
 244         sfa->actions_len = actions_len;
 245         memcpy(sfa->actions, actions, actions_len);
 246
 247         rcu_assign_pointer(flow->sf_acts, sfa);
 248         flow_deferred_free_acts(orig_sfa);
 249
 250         return;
 251 }
 252 EXPORT_SYMBOL(flow_replace_acts);
 253
 254 /* Prints a representation of 'key' to the kernel log. */
 255 void print_flow(const struct sw_flow_key *key)
 256 {
 257         printk("wild%08x port%04x:vlan%04x mac%02x:%02x:%02x:%02x:%02x:%02x"
 258                         "->%02x:%02x:%02x:%02x:%02x:%02x "
 259                         "proto%04x ip%u.%u.%u.%u->%u.%u.%u.%u port%d->%d\n",
 260                         key->wildcards, ntohs(key->in_port), ntohs(key->dl_vlan),
 261                         key->dl_src[0], key->dl_src[1], key->dl_src[2],
 262                         key->dl_src[3], key->dl_src[4], key->dl_src[5],
 263                         key->dl_dst[0], key->dl_dst[1], key->dl_dst[2],
 264                         key->dl_dst[3], key->dl_dst[4], key->dl_dst[5],
 265                         ntohs(key->dl_type),
 266                         ((unsigned char *)&key->nw_src)[0],
 267                         ((unsigned char *)&key->nw_src)[1],
 268                         ((unsigned char *)&key->nw_src)[2],
 269                         ((unsigned char *)&key->nw_src)[3],
 270                         ((unsigned char *)&key->nw_dst)[0],
 271                         ((unsigned char *)&key->nw_dst)[1],
 272                         ((unsigned char *)&key->nw_dst)[2],
 273                         ((unsigned char *)&key->nw_dst)[3],
 274                         ntohs(key->tp_src), ntohs(key->tp_dst));
 275 }
 276 EXPORT_SYMBOL(print_flow);
 277
 278 static int tcphdr_ok(struct sk_buff *skb)
 279 {
 280         int th_ofs = skb_transport_offset(skb);
 281         if (skb->len >= th_ofs + sizeof(struct tcphdr)) {
 282                 int tcp_len = tcp_hdrlen(skb);
 283                 return (tcp_len >= sizeof(struct tcphdr)
 284                         && skb->len >= th_ofs + tcp_len);
 285         }
 286         return 0;
 287 }
 288
 289 static int udphdr_ok(struct sk_buff *skb)
 290 {
 291         int th_ofs = skb_transport_offset(skb);
 292         return skb->len >= th_ofs + sizeof(struct udphdr);
 293 }
 294
 295 /* Parses the Ethernet frame in 'skb', which was received on 'in_port',
 296  * and initializes 'key' to match.  Returns 1 if 'skb' contains an IP
 297  * fragment, 0 otherwise. */
 298 int flow_extract(struct sk_buff *skb, uint16_t in_port,
 299                  struct sw_flow_key *key)
 300 {
 301         struct ethhdr *mac;
 302         int nh_ofs, th_ofs;
 303         int retval = 0;
 304
 305         key->in_port = htons(in_port);
 306         key->pad = 0;
 307         key->wildcards = 0;
 308         key->nw_src_mask = 0;
 309         key->nw_dst_mask = 0;
 310
 311         /* This code doesn't check that skb->len is long enough to contain the
 312          * MAC or network header.  With a 46-byte minimum length frame this
 313          * assumption is always correct. */
 314
 315         /* Doesn't verify checksums.  Should it? */
 316
 317         /* Data link layer.  We only support Ethernet. */
 318         mac = eth_hdr(skb);
 319         nh_ofs = sizeof(struct ethhdr);
 320         if (likely(ntohs(mac->h_proto) >= OFP_DL_TYPE_ETH2_CUTOFF)) {
 321                 /* This is an Ethernet II frame */
 322                 key->dl_type = mac->h_proto;
 323         } else {
 324                 /* This is an 802.2 frame */
 325                 if (snap_get_ethertype(skb, &key->dl_type) != -EINVAL) {
 326                         nh_ofs += sizeof(struct snap_hdr);
 327                 } else {
 328                         key->dl_type = htons(OFP_DL_TYPE_NOT_ETH_TYPE);
 329                         nh_ofs += sizeof(struct llc_pdu_un);
 330                 }
 331         }
 332
 333         /* Check for a VLAN tag */
 334         if (likely(key->dl_type != htons(ETH_P_8021Q))) {
 335                 key->dl_vlan = htons(OFP_VLAN_NONE);
 336         } else {
 337                 struct vlan_hdr *vh = (struct vlan_hdr *)(skb_mac_header(skb) + nh_ofs);
 338                 key->dl_type = vh->h_vlan_encapsulated_proto;
 339                 key->dl_vlan = vh->h_vlan_TCI & htons(VLAN_VID_MASK);
 340                 nh_ofs += sizeof(*vh);
 341         }
 342         memcpy(key->dl_src, mac->h_source, ETH_ALEN);
 343         memcpy(key->dl_dst, mac->h_dest, ETH_ALEN);
 344         skb_set_network_header(skb, nh_ofs);
 345
 346         /* Network layer. */
 347         if (likely(key->dl_type == htons(ETH_P_IP))) {
 348                 struct iphdr *nh = ip_hdr(skb);
 349                 key->nw_src = nh->saddr;
 350                 key->nw_dst = nh->daddr;
 351                 key->nw_proto = nh->protocol;
 352                 th_ofs = nh_ofs + nh->ihl * 4;
 353                 skb_set_transport_header(skb, th_ofs);
 354
 355                 /* Transport layer. */
 356                 if (!(nh->frag_off & htons(IP_MF | IP_OFFSET))) {
 357                         if (key->nw_proto == IPPROTO_TCP) {
 358                                 if (tcphdr_ok(skb)) {
 359                                         struct tcphdr *tcp = tcp_hdr(skb);
 360                                         key->tp_src = tcp->source;
 361                                         key->tp_dst = tcp->dest;
 362                                 } else {
 363                                         /* Avoid tricking other code into
 364                                          * thinking that this packet has an L4
 365                                          * header. */
 366                                         goto no_proto;
 367                                 }
 368                         } else if (key->nw_proto == IPPROTO_UDP) {
 369                                 if (udphdr_ok(skb)) {
 370                                         struct udphdr *udp = udp_hdr(skb);
 371                                         key->tp_src = udp->source;
 372                                         key->tp_dst = udp->dest;
 373                                 } else {
 374                                         /* Avoid tricking other code into
 375                                          * thinking that this packet has an L4
 376                                          * header. */
 377                                         goto no_proto;
 378                                 }
 379                         } else {
 380                                 goto no_th;
 381                         }
 382                 } else {
 383                         retval = 1;
 384                         goto no_th;
 385                 }
 386
 387                 return 0;
 388         }
 389
 390         key->nw_src = 0;
 391         key->nw_dst = 0;
 392
 393 no_proto:
 394         key->nw_proto = 0;
 395
 396 no_th:
 397         key->tp_src = 0;
 398         key->tp_dst = 0;
 399         return retval;
 400 }
 401
 402 /* Initializes the flow module.
 403  * Returns zero if successful or a negative error code. */
 404 int flow_init(void)
 405 {
 406         flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow), 0,
 407                                         0, NULL);
 408         if (flow_cache == NULL)
 409                 return -ENOMEM;
 410
 411         return 0;
 412 }
 413
 414 /* Uninitializes the flow module. */
 415 void flow_exit(void)
 416 {
 417         kmem_cache_destroy(flow_cache);
 418 }
 419