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/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/tcp.h>
  17 #include <linux/udp.h>
  18 #include <linux/in.h>
  19 #include <linux/rcupdate.h>
  20 #include <net/ip.h>
  21
  22 #include "openflow.h"
  23 #include "compat.h"
  24 #include "snap.h"
  25
  26 struct kmem_cache *flow_cache;
  27
  28 /* Internal function used to compare fields in flow. */
  29 static inline
  30 int flow_fields_match(const struct sw_flow_key *a, const struct sw_flow_key *b,
  31                 uint16_t w)
  32 {
  33         return ((w & OFPFW_IN_PORT || a->in_port == b->in_port)
  34                 && (w & OFPFW_DL_VLAN || a->dl_vlan == b->dl_vlan)
  35                 && (w & OFPFW_DL_SRC || !memcmp(a->dl_src, b->dl_src, ETH_ALEN))
  36                 && (w & OFPFW_DL_DST || !memcmp(a->dl_dst, b->dl_dst, ETH_ALEN))
  37                 && (w & OFPFW_DL_TYPE || a->dl_type == b->dl_type)
  38                 && (w & OFPFW_NW_SRC || a->nw_src == b->nw_src)
  39                 && (w & OFPFW_NW_DST || a->nw_dst == b->nw_dst)
  40                 && (w & OFPFW_NW_PROTO || a->nw_proto == b->nw_proto)
  41                 && (w & OFPFW_TP_SRC || a->tp_src == b->tp_src)
  42                 && (w & OFPFW_TP_DST || a->tp_dst == b->tp_dst));
  43 }
  44
  45 /* Returns nonzero if 'a' and 'b' match, that is, if their fields are equal
  46  * modulo wildcards, zero otherwise. */
  47 int flow_matches(const struct sw_flow_key *a, const struct sw_flow_key *b)
  48 {
  49         return flow_fields_match(a, b, (a->wildcards | b->wildcards));
  50 }
  51 EXPORT_SYMBOL(flow_matches);
  52
  53 /* Returns nonzero if 't' (the table entry's key) and 'd' (the key
  54  * describing the deletion) match, that is, if their fields are
  55  * equal modulo wildcards, zero otherwise.  If 'strict' is nonzero, the
  56  * wildcards must match in both 't_key' and 'd_key'.  Note that the
  57  * table's wildcards are ignored unless 'strict' is set. */
  58 int flow_del_matches(const struct sw_flow_key *t, const struct sw_flow_key *d, int strict)
  59 {
  60         if (strict && (t->wildcards != d->wildcards))
  61                 return 0;
  62
  63         return flow_fields_match(t, d, d->wildcards);
  64 }
  65 EXPORT_SYMBOL(flow_del_matches);
  66
  67 void flow_extract_match(struct sw_flow_key* to, const struct ofp_match* from)
  68 {
  69         to->wildcards = ntohs(from->wildcards) & OFPFW_ALL;
  70         memset(to->pad, '\0', sizeof(to->pad));
  71         to->in_port = from->in_port;
  72         to->dl_vlan = from->dl_vlan;
  73         memcpy(to->dl_src, from->dl_src, ETH_ALEN);
  74         memcpy(to->dl_dst, from->dl_dst, ETH_ALEN);
  75         to->dl_type = from->dl_type;
  76
  77         to->nw_src = to->nw_dst = to->nw_proto = 0;
  78         to->tp_src = to->tp_dst = 0;
  79
  80 #define OFPFW_TP (OFPFW_TP_SRC | OFPFW_TP_DST)
  81 #define OFPFW_NW (OFPFW_NW_SRC | OFPFW_NW_DST | OFPFW_NW_PROTO)
  82         if (to->wildcards & OFPFW_DL_TYPE) {
  83                 /* Can't sensibly match on network or transport headers if the
  84                  * data link type is unknown. */
  85                 to->wildcards |= OFPFW_NW | OFPFW_TP;
  86         } else if (from->dl_type == htons(ETH_P_IP)) {
  87                 to->nw_src   = from->nw_src;
  88                 to->nw_dst   = from->nw_dst;
  89                 to->nw_proto = from->nw_proto;
  90
  91                 if (to->wildcards & OFPFW_NW_PROTO) {
  92                         /* Can't sensibly match on transport headers if the
  93                          * network protocol is unknown. */
  94                         to->wildcards |= OFPFW_TP;
  95                 } else if (from->nw_proto == IPPROTO_TCP
  96                            || from->nw_proto == IPPROTO_UDP) {
  97                         to->tp_src = from->tp_src;
  98                         to->tp_dst = from->tp_dst;
  99                 } else {
 100                         /* Transport layer fields are undefined.  Mark them as
 101                          * exact-match to allow such flows to reside in
 102                          * table-hash, instead of falling into table-linear. */
 103                         to->wildcards &= ~OFPFW_TP;
 104                 }
 105         } else {
 106                 /* Network and transport layer fields are undefined.  Mark them
 107                  * as exact-match to allow such flows to reside in table-hash,
 108                  * instead of falling into table-linear. */
 109                 to->wildcards &= ~(OFPFW_NW | OFPFW_TP);
 110         }
 111 }
 112
 113 void flow_fill_match(struct ofp_match* to, const struct sw_flow_key* from)
 114 {
 115         to->wildcards = htons(from->wildcards);
 116         to->in_port   = from->in_port;
 117         to->dl_vlan   = from->dl_vlan;
 118         memcpy(to->dl_src, from->dl_src, ETH_ALEN);
 119         memcpy(to->dl_dst, from->dl_dst, ETH_ALEN);
 120         to->dl_type   = from->dl_type;
 121         to->nw_src        = from->nw_src;
 122         to->nw_dst        = from->nw_dst;
 123         to->nw_proto  = from->nw_proto;
 124         to->tp_src        = from->tp_src;
 125         to->tp_dst        = from->tp_dst;
 126         memset(to->pad, '\0', sizeof(to->pad));
 127 }
 128
 129 /* Allocates and returns a new flow with 'n_actions' action, using allocation
 130  * flags 'flags'.  Returns the new flow or a null pointer on failure. */
 131 struct sw_flow *flow_alloc(int n_actions, gfp_t flags)
 132 {
 133         struct sw_flow *flow = kmem_cache_alloc(flow_cache, flags);
 134         if (unlikely(!flow))
 135                 return NULL;
 136
 137         flow->n_actions = n_actions;
 138         flow->actions = kmalloc(n_actions * sizeof *flow->actions,
 139                                 flags);
 140         if (unlikely(!flow->actions) && n_actions > 0) {
 141                 kmem_cache_free(flow_cache, flow);
 142                 return NULL;
 143         }
 144         return flow;
 145 }
 146
 147 /* Frees 'flow' immediately. */
 148 void flow_free(struct sw_flow *flow)
 149 {
 150         if (unlikely(!flow))
 151                 return;
 152         kfree(flow->actions);
 153         kmem_cache_free(flow_cache, flow);
 154 }
 155 EXPORT_SYMBOL(flow_free);
 156
 157 /* RCU callback used by flow_deferred_free. */
 158 static void rcu_callback(struct rcu_head *rcu)
 159 {
 160         struct sw_flow *flow = container_of(rcu, struct sw_flow, rcu);
 161         flow_free(flow);
 162 }
 163
 164 /* Schedules 'flow' to be freed after the next RCU grace period.
 165  * The caller must hold rcu_read_lock for this to be sensible. */
 166 void flow_deferred_free(struct sw_flow *flow)
 167 {
 168         call_rcu(&flow->rcu, rcu_callback);
 169 }
 170 EXPORT_SYMBOL(flow_deferred_free);
 171
 172 /* Prints a representation of 'key' to the kernel log. */
 173 void print_flow(const struct sw_flow_key *key)
 174 {
 175         printk("wild%04x port%04x:vlan%04x mac%02x:%02x:%02x:%02x:%02x:%02x"
 176                         "->%02x:%02x:%02x:%02x:%02x:%02x "
 177                         "proto%04x ip%u.%u.%u.%u->%u.%u.%u.%u port%d->%d\n",
 178                         key->wildcards, ntohs(key->in_port), ntohs(key->dl_vlan),
 179                         key->dl_src[0], key->dl_src[1], key->dl_src[2],
 180                         key->dl_src[3], key->dl_src[4], key->dl_src[5],
 181                         key->dl_dst[0], key->dl_dst[1], key->dl_dst[2],
 182                         key->dl_dst[3], key->dl_dst[4], key->dl_dst[5],
 183                         ntohs(key->dl_type),
 184                         ((unsigned char *)&key->nw_src)[0],
 185                         ((unsigned char *)&key->nw_src)[1],
 186                         ((unsigned char *)&key->nw_src)[2],
 187                         ((unsigned char *)&key->nw_src)[3],
 188                         ((unsigned char *)&key->nw_dst)[0],
 189                         ((unsigned char *)&key->nw_dst)[1],
 190                         ((unsigned char *)&key->nw_dst)[2],
 191                         ((unsigned char *)&key->nw_dst)[3],
 192                         ntohs(key->tp_src), ntohs(key->tp_dst));
 193 }
 194 EXPORT_SYMBOL(print_flow);
 195
 196 /* Parses the Ethernet frame in 'skb', which was received on 'in_port',
 197  * and initializes 'key' to match. */
 198 void flow_extract(struct sk_buff *skb, uint16_t in_port,
 199                   struct sw_flow_key *key)
 200 {
 201         struct ethhdr *mac;
 202         struct udphdr *th;
 203         int nh_ofs, th_ofs;
 204
 205         key->in_port = htons(in_port);
 206         key->wildcards = 0;
 207         memset(key->pad, '\0', sizeof(key->pad));
 208
 209         /* This code doesn't check that skb->len is long enough to contain the
 210          * MAC or network header.  With a 46-byte minimum length frame this
 211          * assumption is always correct. */
 212
 213         /* Doesn't verify checksums.  Should it? */
 214
 215         /* Data link layer.  We only support Ethernet. */
 216         mac = eth_hdr(skb);
 217         nh_ofs = sizeof(struct ethhdr);
 218         if (likely(ntohs(mac->h_proto) >= OFP_DL_TYPE_ETH2_CUTOFF)) {
 219                 /* This is an Ethernet II frame */
 220                 key->dl_type = mac->h_proto;
 221         } else {
 222                 /* This is an 802.2 frame */
 223                 if (snap_get_ethertype(skb, &key->dl_type) != -EINVAL) {
 224                         nh_ofs += sizeof(struct snap_hdr);
 225                 } else {
 226                         key->dl_type = OFP_DL_TYPE_NOT_ETH_TYPE;
 227                         nh_ofs += sizeof(struct llc_pdu_un);
 228                 }
 229         }
 230
 231         /* Check for a VLAN tag */
 232         if (likely(key->dl_type != htons(ETH_P_8021Q))) {
 233                 key->dl_vlan = htons(OFP_VLAN_NONE);
 234         } else {
 235                 struct vlan_hdr *vh = (struct vlan_hdr *)(skb_mac_header(skb) + nh_ofs);
 236                 key->dl_type = vh->h_vlan_encapsulated_proto;
 237                 key->dl_vlan = vh->h_vlan_TCI & htons(VLAN_VID_MASK);
 238                 nh_ofs += sizeof(*vh);
 239         }
 240         memcpy(key->dl_src, mac->h_source, ETH_ALEN);
 241         memcpy(key->dl_dst, mac->h_dest, ETH_ALEN);
 242         skb_set_network_header(skb, nh_ofs);
 243
 244         /* Network layer. */
 245         if (likely(key->dl_type == htons(ETH_P_IP))) {
 246                 struct iphdr *nh = ip_hdr(skb);
 247                 key->nw_src = nh->saddr;
 248                 key->nw_dst = nh->daddr;
 249                 key->nw_proto = nh->protocol;
 250                 th_ofs = nh_ofs + nh->ihl * 4;
 251                 skb_set_transport_header(skb, th_ofs);
 252
 253                 /* Transport layer. */
 254                 if ((key->nw_proto != IPPROTO_TCP && key->nw_proto != IPPROTO_UDP)
 255                     || skb->len < th_ofs + sizeof(struct udphdr)
 256                     || nh->frag_off & htons(IP_MF | IP_OFFSET)) {
 257                         goto no_th;
 258                 }
 259                 th = udp_hdr(skb);
 260                 key->tp_src = th->source;
 261                 key->tp_dst = th->dest;
 262
 263                 return;
 264         }
 265
 266         key->nw_src = 0;
 267         key->nw_dst = 0;
 268         key->nw_proto = 0;
 269
 270 no_th:
 271         key->tp_src = 0;
 272         key->tp_dst = 0;
 273 }
 274
 275 /* Initializes the flow module.
 276  * Returns zero if successful or a negative error code. */
 277 int flow_init(void)
 278 {
 279         flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow), 0,
 280                                         0, NULL);
 281         if (flow_cache == NULL)
 282                 return -ENOMEM;
 283
 284         return 0;
 285 }
 286
 287 /* Uninitializes the flow module. */
 288 void flow_exit(void)
 289 {
 290         kmem_cache_destroy(flow_cache);
 291 }
 292