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                 uint16_t w)
  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                 && (w & OFPFW_NW_SRC || a->nw_src == b->nw_src)
  40                 && (w & OFPFW_NW_DST || a->nw_dst == b->nw_dst)
  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, zero otherwise. */
  48 int flow_matches(const struct sw_flow_key *a, const struct sw_flow_key *b)
  49 {
  50         return flow_fields_match(a, b, (a->wildcards | b->wildcards));
  51 }
  52 EXPORT_SYMBOL(flow_matches);
  53
  54 /* Returns nonzero if 't' (the table entry's key) and 'd' (the key
  55  * describing the deletion) match, that is, if their fields are
  56  * equal modulo wildcards, zero otherwise.  If 'strict' is nonzero, the
  57  * wildcards must match in both 't_key' and 'd_key'.  Note that the
  58  * table's wildcards are ignored unless 'strict' is set. */
  59 int flow_del_matches(const struct sw_flow_key *t, const struct sw_flow_key *d, int strict)
  60 {
  61         if (strict && (t->wildcards != d->wildcards))
  62                 return 0;
  63
  64         return flow_fields_match(t, d, d->wildcards);
  65 }
  66 EXPORT_SYMBOL(flow_del_matches);
  67
  68 void flow_extract_match(struct sw_flow_key* to, const struct ofp_match* from)
  69 {
  70         to->wildcards = ntohs(from->wildcards) & OFPFW_ALL;
  71         memset(to->pad, '\0', sizeof(to->pad));
  72         to->in_port = from->in_port;
  73         to->dl_vlan = from->dl_vlan;
  74         memcpy(to->dl_src, from->dl_src, ETH_ALEN);
  75         memcpy(to->dl_dst, from->dl_dst, ETH_ALEN);
  76         to->dl_type = from->dl_type;
  77
  78         to->nw_src = to->nw_dst = to->nw_proto = 0;
  79         to->tp_src = to->tp_dst = 0;
  80
  81 #define OFPFW_TP (OFPFW_TP_SRC | OFPFW_TP_DST)
  82 #define OFPFW_NW (OFPFW_NW_SRC | OFPFW_NW_DST | OFPFW_NW_PROTO)
  83         if (to->wildcards & OFPFW_DL_TYPE) {
  84                 /* Can't sensibly match on network or transport headers if the
  85                  * data link type is unknown. */
  86                 to->wildcards |= OFPFW_NW | OFPFW_TP;
  87         } else if (from->dl_type == htons(ETH_P_IP)) {
  88                 to->nw_src   = from->nw_src;
  89                 to->nw_dst   = from->nw_dst;
  90                 to->nw_proto = from->nw_proto;
  91
  92                 if (to->wildcards & OFPFW_NW_PROTO) {
  93                         /* Can't sensibly match on transport headers if the
  94                          * network protocol is unknown. */
  95                         to->wildcards |= OFPFW_TP;
  96                 } else if (from->nw_proto == IPPROTO_TCP
  97                            || from->nw_proto == IPPROTO_UDP) {
  98                         to->tp_src = from->tp_src;
  99                         to->tp_dst = from->tp_dst;
 100                 } else {
 101                         /* Transport layer fields are undefined.  Mark them as
 102                          * exact-match to allow such flows to reside in
 103                          * table-hash, instead of falling into table-linear. */
 104                         to->wildcards &= ~OFPFW_TP;
 105                 }
 106         } else {
 107                 /* Network and transport layer fields are undefined.  Mark them
 108                  * as exact-match to allow such flows to reside in table-hash,
 109                  * instead of falling into table-linear. */
 110                 to->wildcards &= ~(OFPFW_NW | OFPFW_TP);
 111         }
 112 }
 113
 114 void flow_fill_match(struct ofp_match* to, const struct sw_flow_key* from)
 115 {
 116         to->wildcards = htons(from->wildcards);
 117         to->in_port   = from->in_port;
 118         to->dl_vlan   = from->dl_vlan;
 119         memcpy(to->dl_src, from->dl_src, ETH_ALEN);
 120         memcpy(to->dl_dst, from->dl_dst, ETH_ALEN);
 121         to->dl_type   = from->dl_type;
 122         to->nw_src        = from->nw_src;
 123         to->nw_dst        = from->nw_dst;
 124         to->nw_proto  = from->nw_proto;
 125         to->tp_src        = from->tp_src;
 126         to->tp_dst        = from->tp_dst;
 127         memset(to->pad, '\0', sizeof(to->pad));
 128 }
 129
 130 int flow_timeout(struct sw_flow *flow)
 131 {
 132         if (flow->idle_timeout != OFP_FLOW_PERMANENT
 133             && time_after(jiffies, flow->used + flow->idle_timeout * HZ))
 134                 return OFPER_IDLE_TIMEOUT;
 135         else if (flow->hard_timeout != OFP_FLOW_PERMANENT
 136                  && time_after(jiffies,
 137                                flow->init_time + flow->hard_timeout * HZ))
 138                 return OFPER_HARD_TIMEOUT;
 139         else
 140                 return -1;
 141 }
 142 EXPORT_SYMBOL(flow_timeout);
 143
 144 /* Allocates and returns a new flow with 'n_actions' action, using allocation
 145  * flags 'flags'.  Returns the new flow or a null pointer on failure. */
 146 struct sw_flow *flow_alloc(int n_actions, gfp_t flags)
 147 {
 148         struct sw_flow *flow = kmem_cache_alloc(flow_cache, flags);
 149         if (unlikely(!flow))
 150                 return NULL;
 151
 152         flow->n_actions = n_actions;
 153         flow->actions = kmalloc(n_actions * sizeof *flow->actions,
 154                                 flags);
 155         if (unlikely(!flow->actions) && n_actions > 0) {
 156                 kmem_cache_free(flow_cache, flow);
 157                 return NULL;
 158         }
 159         return flow;
 160 }
 161
 162 /* Frees 'flow' immediately. */
 163 void flow_free(struct sw_flow *flow)
 164 {
 165         if (unlikely(!flow))
 166                 return;
 167         kfree(flow->actions);
 168         kmem_cache_free(flow_cache, flow);
 169 }
 170 EXPORT_SYMBOL(flow_free);
 171
 172 /* RCU callback used by flow_deferred_free. */
 173 static void rcu_callback(struct rcu_head *rcu)
 174 {
 175         struct sw_flow *flow = container_of(rcu, struct sw_flow, rcu);
 176         flow_free(flow);
 177 }
 178
 179 /* Schedules 'flow' to be freed after the next RCU grace period.
 180  * The caller must hold rcu_read_lock for this to be sensible. */
 181 void flow_deferred_free(struct sw_flow *flow)
 182 {
 183         call_rcu(&flow->rcu, rcu_callback);
 184 }
 185 EXPORT_SYMBOL(flow_deferred_free);
 186
 187 /* Prints a representation of 'key' to the kernel log. */
 188 void print_flow(const struct sw_flow_key *key)
 189 {
 190         printk("wild%04x port%04x:vlan%04x mac%02x:%02x:%02x:%02x:%02x:%02x"
 191                         "->%02x:%02x:%02x:%02x:%02x:%02x "
 192                         "proto%04x ip%u.%u.%u.%u->%u.%u.%u.%u port%d->%d\n",
 193                         key->wildcards, ntohs(key->in_port), ntohs(key->dl_vlan),
 194                         key->dl_src[0], key->dl_src[1], key->dl_src[2],
 195                         key->dl_src[3], key->dl_src[4], key->dl_src[5],
 196                         key->dl_dst[0], key->dl_dst[1], key->dl_dst[2],
 197                         key->dl_dst[3], key->dl_dst[4], key->dl_dst[5],
 198                         ntohs(key->dl_type),
 199                         ((unsigned char *)&key->nw_src)[0],
 200                         ((unsigned char *)&key->nw_src)[1],
 201                         ((unsigned char *)&key->nw_src)[2],
 202                         ((unsigned char *)&key->nw_src)[3],
 203                         ((unsigned char *)&key->nw_dst)[0],
 204                         ((unsigned char *)&key->nw_dst)[1],
 205                         ((unsigned char *)&key->nw_dst)[2],
 206                         ((unsigned char *)&key->nw_dst)[3],
 207                         ntohs(key->tp_src), ntohs(key->tp_dst));
 208 }
 209 EXPORT_SYMBOL(print_flow);
 210
 211 static int tcphdr_ok(struct sk_buff *skb)
 212 {
 213         int th_ofs = skb_transport_offset(skb);
 214         if (skb->len >= th_ofs + sizeof(struct tcphdr)) {
 215                 int tcp_len = tcp_hdrlen(skb);
 216                 return (tcp_len >= sizeof(struct tcphdr)
 217                         && skb->len >= th_ofs + tcp_len);
 218         }
 219         return 0;
 220 }
 221
 222 static int udphdr_ok(struct sk_buff *skb)
 223 {
 224         int th_ofs = skb_transport_offset(skb);
 225         return skb->len >= th_ofs + sizeof(struct udphdr);
 226 }
 227
 228 /* Parses the Ethernet frame in 'skb', which was received on 'in_port',
 229  * and initializes 'key' to match.  Returns 1 if 'skb' contains an IP
 230  * fragment, 0 otherwise. */
 231 int flow_extract(struct sk_buff *skb, uint16_t in_port,
 232                  struct sw_flow_key *key)
 233 {
 234         struct ethhdr *mac;
 235         int nh_ofs, th_ofs;
 236         int retval = 0;
 237
 238         key->in_port = htons(in_port);
 239         key->wildcards = 0;
 240         memset(key->pad, '\0', sizeof(key->pad));
 241
 242         /* This code doesn't check that skb->len is long enough to contain the
 243          * MAC or network header.  With a 46-byte minimum length frame this
 244          * assumption is always correct. */
 245
 246         /* Doesn't verify checksums.  Should it? */
 247
 248         /* Data link layer.  We only support Ethernet. */
 249         mac = eth_hdr(skb);
 250         nh_ofs = sizeof(struct ethhdr);
 251         if (likely(ntohs(mac->h_proto) >= OFP_DL_TYPE_ETH2_CUTOFF)) {
 252                 /* This is an Ethernet II frame */
 253                 key->dl_type = mac->h_proto;
 254         } else {
 255                 /* This is an 802.2 frame */
 256                 if (snap_get_ethertype(skb, &key->dl_type) != -EINVAL) {
 257                         nh_ofs += sizeof(struct snap_hdr);
 258                 } else {
 259                         key->dl_type = OFP_DL_TYPE_NOT_ETH_TYPE;
 260                         nh_ofs += sizeof(struct llc_pdu_un);
 261                 }
 262         }
 263
 264         /* Check for a VLAN tag */
 265         if (likely(key->dl_type != htons(ETH_P_8021Q))) {
 266                 key->dl_vlan = htons(OFP_VLAN_NONE);
 267         } else {
 268                 struct vlan_hdr *vh = (struct vlan_hdr *)(skb_mac_header(skb) + nh_ofs);
 269                 key->dl_type = vh->h_vlan_encapsulated_proto;
 270                 key->dl_vlan = vh->h_vlan_TCI & htons(VLAN_VID_MASK);
 271                 nh_ofs += sizeof(*vh);
 272         }
 273         memcpy(key->dl_src, mac->h_source, ETH_ALEN);
 274         memcpy(key->dl_dst, mac->h_dest, ETH_ALEN);
 275         skb_set_network_header(skb, nh_ofs);
 276
 277         /* Network layer. */
 278         if (likely(key->dl_type == htons(ETH_P_IP))) {
 279                 struct iphdr *nh = ip_hdr(skb);
 280                 key->nw_src = nh->saddr;
 281                 key->nw_dst = nh->daddr;
 282                 key->nw_proto = nh->protocol;
 283                 th_ofs = nh_ofs + nh->ihl * 4;
 284                 skb_set_transport_header(skb, th_ofs);
 285
 286                 /* Transport layer. */
 287                 if (!(nh->frag_off & htons(IP_MF | IP_OFFSET))) {
 288                         if (key->nw_proto == IPPROTO_TCP) {
 289                                 if (tcphdr_ok(skb)) {
 290                                         struct tcphdr *tcp = tcp_hdr(skb);
 291                                         key->tp_src = tcp->source;
 292                                         key->tp_dst = tcp->dest;
 293                                 } else {
 294                                         /* Avoid tricking other code into
 295                                          * thinking that this packet has an L4
 296                                          * header. */
 297                                         goto no_proto;
 298                                 }
 299                         } else if (key->nw_proto == IPPROTO_UDP) {
 300                                 if (udphdr_ok(skb)) {
 301                                         struct udphdr *udp = udp_hdr(skb);
 302                                         key->tp_src = udp->source;
 303                                         key->tp_dst = udp->dest;
 304                                 } else {
 305                                         /* Avoid tricking other code into
 306                                          * thinking that this packet has an L4
 307                                          * header. */
 308                                         goto no_proto;
 309                                 }
 310                         } else {
 311                                 goto no_th;
 312                         }
 313                 } else {
 314                         retval = 1;
 315                         goto no_th;
 316                 }
 317
 318                 return 0;
 319         }
 320
 321         key->nw_src = 0;
 322         key->nw_dst = 0;
 323
 324 no_proto:
 325         key->nw_proto = 0;
 326
 327 no_th:
 328         key->tp_src = 0;
 329         key->tp_dst = 0;
 330         return retval;
 331 }
 332
 333 /* Initializes the flow module.
 334  * Returns zero if successful or a negative error code. */
 335 int flow_init(void)
 336 {
 337         flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow), 0,
 338                                         0, NULL);
 339         if (flow_cache == NULL)
 340                 return -ENOMEM;
 341
 342         return 0;
 343 }
 344
 345 /* Uninitializes the flow module. */
 346 void flow_exit(void)
 347 {
 348         kmem_cache_destroy(flow_cache);
 349 }
 350