datapath/flow.c

   1 /*
   2  * Distributed under the terms of the GNU GPL version 2.
   3  * Copyright (c) 2007, 2008, 2009 Nicira Networks.
   4  */
   5
   6 #include "flow.h"
   7 #include <linux/netdevice.h>
   8 #include <linux/etherdevice.h>
   9 #include <linux/if_ether.h>
  10 #include <linux/if_vlan.h>
  11 #include <net/llc_pdu.h>
  12 #include <linux/kernel.h>
  13 #include <linux/jiffies.h>
  14 #include <linux/llc.h>
  15 #include <linux/module.h>
  16 #include <linux/in.h>
  17 #include <linux/rcupdate.h>
  18 #include <linux/if_ether.h>
  19 #include <linux/ip.h>
  20 #include <linux/tcp.h>
  21 #include <linux/udp.h>
  22 #include <linux/icmp.h>
  23 #include <net/ip.h>
  24
  25 #include "compat.h"
  26
  27 struct kmem_cache *flow_cache;
  28
  29 static inline int iphdr_ok(struct sk_buff *skb)
  30 {
  31         int nh_ofs = skb_network_offset(skb);
  32         if (skb->len >= nh_ofs + sizeof(struct iphdr)) {
  33                 int ip_len = ip_hdrlen(skb);
  34                 return (ip_len >= sizeof(struct iphdr)
  35                         && pskb_may_pull(skb, nh_ofs + ip_len));
  36         }
  37         return 0;
  38 }
  39
  40 static inline int tcphdr_ok(struct sk_buff *skb)
  41 {
  42         int th_ofs = skb_transport_offset(skb);
  43         if (pskb_may_pull(skb, th_ofs + sizeof(struct tcphdr))) {
  44                 int tcp_len = tcp_hdrlen(skb);
  45                 return (tcp_len >= sizeof(struct tcphdr)
  46                         && skb->len >= th_ofs + tcp_len);
  47         }
  48         return 0;
  49 }
  50
  51 static inline int udphdr_ok(struct sk_buff *skb)
  52 {
  53         int th_ofs = skb_transport_offset(skb);
  54         return pskb_may_pull(skb, th_ofs + sizeof(struct udphdr));
  55 }
  56
  57 static inline int icmphdr_ok(struct sk_buff *skb)
  58 {
  59         int th_ofs = skb_transport_offset(skb);
  60         return pskb_may_pull(skb, th_ofs + sizeof(struct icmphdr));
  61 }
  62
  63 #define TCP_FLAGS_OFFSET 13
  64 #define TCP_FLAG_MASK 0x3f
  65
  66 static inline struct ovs_tcphdr *ovs_tcp_hdr(const struct sk_buff *skb)
  67 {
  68         return (struct ovs_tcphdr *)skb_transport_header(skb);
  69 }
  70
  71 void flow_used(struct sw_flow *flow, struct sk_buff *skb)
  72 {
  73         unsigned long flags;
  74         u8 tcp_flags = 0;
  75
  76         if (flow->key.dl_type == htons(ETH_P_IP) && iphdr_ok(skb)) {
  77                 struct iphdr *nh = ip_hdr(skb);
  78                 flow->ip_tos = nh->tos;
  79                 if (flow->key.nw_proto == IPPROTO_TCP && tcphdr_ok(skb)) {
  80                         u8 *tcp = (u8 *)tcp_hdr(skb);
  81                         tcp_flags = *(tcp + TCP_FLAGS_OFFSET) & TCP_FLAG_MASK;
  82                 }
  83         }
  84
  85         spin_lock_irqsave(&flow->lock, flags);
  86         getnstimeofday(&flow->used);
  87         flow->packet_count++;
  88         flow->byte_count += skb->len;
  89         flow->tcp_flags |= tcp_flags;
  90         spin_unlock_irqrestore(&flow->lock, flags);
  91 }
  92
  93 struct sw_flow_actions *flow_actions_alloc(size_t n_actions)
  94 {
  95         struct sw_flow_actions *sfa;
  96
  97         if (n_actions > (PAGE_SIZE - sizeof *sfa) / sizeof(union odp_action))
  98                 return ERR_PTR(-EINVAL);
  99
 100         sfa = kmalloc(sizeof *sfa + n_actions * sizeof(union odp_action),
 101                       GFP_KERNEL);
 102         if (!sfa)
 103                 return ERR_PTR(-ENOMEM);
 104
 105         sfa->n_actions = n_actions;
 106         return sfa;
 107 }
 108
 109
 110 /* Frees 'flow' immediately. */
 111 void flow_free(struct sw_flow *flow)
 112 {
 113         if (unlikely(!flow))
 114                 return;
 115         kfree(flow->sf_acts);
 116         kmem_cache_free(flow_cache, flow);
 117 }
 118
 119 /* RCU callback used by flow_deferred_free. */
 120 static void rcu_free_flow_callback(struct rcu_head *rcu)
 121 {
 122         struct sw_flow *flow = container_of(rcu, struct sw_flow, rcu);
 123         flow_free(flow);
 124 }
 125
 126 /* Schedules 'flow' to be freed after the next RCU grace period.
 127  * The caller must hold rcu_read_lock for this to be sensible. */
 128 void flow_deferred_free(struct sw_flow *flow)
 129 {
 130         call_rcu(&flow->rcu, rcu_free_flow_callback);
 131 }
 132
 133 /* RCU callback used by flow_deferred_free_acts. */
 134 static void rcu_free_acts_callback(struct rcu_head *rcu)
 135 {
 136         struct sw_flow_actions *sf_acts = container_of(rcu,
 137                         struct sw_flow_actions, rcu);
 138         kfree(sf_acts);
 139 }
 140
 141 /* Schedules 'sf_acts' to be freed after the next RCU grace period.
 142  * The caller must hold rcu_read_lock for this to be sensible. */
 143 void flow_deferred_free_acts(struct sw_flow_actions *sf_acts)
 144 {
 145         call_rcu(&sf_acts->rcu, rcu_free_acts_callback);
 146 }
 147
 148 #define SNAP_OUI_LEN 3
 149
 150 struct eth_snap_hdr
 151 {
 152         struct ethhdr eth;
 153         u8  dsap;  /* Always 0xAA */
 154         u8  ssap;  /* Always 0xAA */
 155         u8  ctrl;
 156         u8  oui[SNAP_OUI_LEN];
 157         u16 ethertype;
 158 } __attribute__ ((packed));
 159
 160 static int is_snap(const struct eth_snap_hdr *esh)
 161 {
 162         return (esh->dsap == LLC_SAP_SNAP
 163                 && esh->ssap == LLC_SAP_SNAP
 164                 && !memcmp(esh->oui, "\0\0\0", 3));
 165 }
 166
 167 /* Parses the Ethernet frame in 'skb', which was received on 'in_port',
 168  * and initializes 'key' to match.  Returns 1 if 'skb' contains an IP
 169  * fragment, 0 otherwise. */
 170 int flow_extract(struct sk_buff *skb, u16 in_port, struct odp_flow_key *key)
 171 {
 172         struct ethhdr *eth;
 173         struct eth_snap_hdr *esh;
 174         int retval = 0;
 175         int nh_ofs;
 176
 177         memset(key, 0, sizeof *key);
 178         key->dl_vlan = htons(ODP_VLAN_NONE);
 179         key->in_port = in_port;
 180
 181         if (skb->len < sizeof *eth)
 182                 return 0;
 183         if (!pskb_may_pull(skb, skb->len >= 64 ? 64 : skb->len)) {
 184                 return 0;
 185         }
 186
 187         skb_reset_mac_header(skb);
 188         eth = eth_hdr(skb);
 189         esh = (struct eth_snap_hdr *) eth;
 190         nh_ofs = sizeof *eth;
 191         if (likely(ntohs(eth->h_proto) >= ODP_DL_TYPE_ETH2_CUTOFF))
 192                 key->dl_type = eth->h_proto;
 193         else if (skb->len >= sizeof *esh && is_snap(esh)) {
 194                 key->dl_type = esh->ethertype;
 195                 nh_ofs = sizeof *esh;
 196         } else {
 197                 key->dl_type = htons(ODP_DL_TYPE_NOT_ETH_TYPE);
 198                 if (skb->len >= nh_ofs + sizeof(struct llc_pdu_un)) {
 199                         nh_ofs += sizeof(struct llc_pdu_un);
 200                 }
 201         }
 202
 203         /* Check for a VLAN tag */
 204         if (key->dl_type == htons(ETH_P_8021Q) &&
 205             skb->len >= nh_ofs + sizeof(struct vlan_hdr)) {
 206                 struct vlan_hdr *vh = (struct vlan_hdr*)(skb->data + nh_ofs);
 207                 key->dl_type = vh->h_vlan_encapsulated_proto;
 208                 key->dl_vlan = vh->h_vlan_TCI & htons(VLAN_VID_MASK);
 209                 nh_ofs += sizeof(struct vlan_hdr);
 210         }
 211         memcpy(key->dl_src, eth->h_source, ETH_ALEN);
 212         memcpy(key->dl_dst, eth->h_dest, ETH_ALEN);
 213         skb_set_network_header(skb, nh_ofs);
 214
 215         /* Network layer. */
 216         if (key->dl_type == htons(ETH_P_IP) && iphdr_ok(skb)) {
 217                 struct iphdr *nh = ip_hdr(skb);
 218                 int th_ofs = nh_ofs + nh->ihl * 4;
 219                 key->nw_src = nh->saddr;
 220                 key->nw_dst = nh->daddr;
 221                 key->nw_proto = nh->protocol;
 222                 skb_set_transport_header(skb, th_ofs);
 223
 224                 /* Transport layer. */
 225                 if (!(nh->frag_off & htons(IP_MF | IP_OFFSET))) {
 226                         if (key->nw_proto == IPPROTO_TCP) {
 227                                 if (tcphdr_ok(skb)) {
 228                                         struct tcphdr *tcp = tcp_hdr(skb);
 229                                         key->tp_src = tcp->source;
 230                                         key->tp_dst = tcp->dest;
 231                                 } else {
 232                                         /* Avoid tricking other code into
 233                                          * thinking that this packet has an L4
 234                                          * header. */
 235                                         key->nw_proto = 0;
 236                                 }
 237                         } else if (key->nw_proto == IPPROTO_UDP) {
 238                                 if (udphdr_ok(skb)) {
 239                                         struct udphdr *udp = udp_hdr(skb);
 240                                         key->tp_src = udp->source;
 241                                         key->tp_dst = udp->dest;
 242                                 } else {
 243                                         /* Avoid tricking other code into
 244                                          * thinking that this packet has an L4
 245                                          * header. */
 246                                         key->nw_proto = 0;
 247                                 }
 248                         } else if (key->nw_proto == IPPROTO_ICMP) {
 249                                 if (icmphdr_ok(skb)) {
 250                                         struct icmphdr *icmp = icmp_hdr(skb);
 251                                         /* The ICMP type and code fields use the 16-bit
 252                                          * transport port fields, so we need to store them
 253                                          * in 16-bit network byte order. */
 254                                         key->tp_src = htons(icmp->type);
 255                                         key->tp_dst = htons(icmp->code);
 256                                 } else {
 257                                         /* Avoid tricking other code into
 258                                          * thinking that this packet has an L4
 259                                          * header. */
 260                                         key->nw_proto = 0;
 261                                 }
 262                         }
 263                 } else {
 264                         retval = 1;
 265                 }
 266         } else {
 267                 skb_reset_transport_header(skb);
 268         }
 269         return retval;
 270 }
 271
 272 /* Initializes the flow module.
 273  * Returns zero if successful or a negative error code. */
 274 int flow_init(void)
 275 {
 276         flow_cache = kmem_cache_create("sw_flow", sizeof(struct sw_flow), 0,
 277                                         0, NULL);
 278         if (flow_cache == NULL)
 279                 return -ENOMEM;
 280
 281         return 0;
 282 }
 283
 284 /* Uninitializes the flow module. */
 285 void flow_exit(void)
 286 {
 287         kmem_cache_destroy(flow_cache);
 288 }
 289
 290 void print_flow(const struct odp_flow_key *key)
 291 {
 292 #define MAC_FMT "%02x:%02x:%02x:%02x:%02x:%02x"
 293 #define MAC_ARG(x) ((u8*)(x))[0],((u8*)(x))[1],((u8*)(x))[2],((u8*)(x))[3],((u8*)(x))[4],((u8*)(x))[5]
 294     printk("port%04x:vlan%d mac"MAC_FMT"->"MAC_FMT" "
 295            "type%04x proto%d ip%x->%x port%d->%d\n",
 296            key->in_port, ntohs(key->dl_vlan),
 297            MAC_ARG(key->dl_src), MAC_ARG(key->dl_dst),
 298            ntohs(key->dl_type), key->nw_proto,
 299            key->nw_src, key->nw_dst,
 300            ntohs(key->tp_src), ntohs(key->tp_dst));
 301 }