net/hsr/hsr_forward.c

   1 /* Copyright 2011-2014 Autronica Fire and Security AS
   2  *
   3  * This program is free software; you can redistribute it and/or modify it
   4  * under the terms of the GNU General Public License as published by the Free
   5  * Software Foundation; either version 2 of the License, or (at your option)
   6  * any later version.
   7  *
   8  * Author(s):
   9  *      2011-2014 Arvid Brodin, arvid.brodin@alten.se
  10  */
  11
  12 #include "hsr_forward.h"
  13 #include <linux/types.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/etherdevice.h>
  16 #include <linux/if_vlan.h>
  17 #include "hsr_main.h"
  18 #include "hsr_framereg.h"
  19
  20
  21 struct hsr_node;
  22
  23 struct hsr_frame_info {
  24         struct sk_buff *skb_std;
  25         struct sk_buff *skb_hsr;
  26         struct hsr_port *port_rcv;
  27         struct hsr_node *node_src;
  28         u16 sequence_nr;
  29         bool is_supervision;
  30         bool is_vlan;
  31         bool is_local_dest;
  32         bool is_local_exclusive;
  33 };
  34
  35
  36 /* The uses I can see for these HSR supervision frames are:
  37  * 1) Use the frames that are sent after node initialization ("HSR_TLV.Type =
  38  *    22") to reset any sequence_nr counters belonging to that node. Useful if
  39  *    the other node's counter has been reset for some reason.
  40  *    --
  41  *    Or not - resetting the counter and bridging the frame would create a
  42  *    loop, unfortunately.
  43  *
  44  * 2) Use the LifeCheck frames to detect ring breaks. I.e. if no LifeCheck
  45  *    frame is received from a particular node, we know something is wrong.
  46  *    We just register these (as with normal frames) and throw them away.
  47  *
  48  * 3) Allow different MAC addresses for the two slave interfaces, using the
  49  *    MacAddressA field.
  50  */
  51 static bool is_supervision_frame(struct hsr_priv *hsr, struct sk_buff *skb)
  52 {
  53         struct hsr_ethhdr_sp *hdr;
  54
  55         WARN_ON_ONCE(!skb_mac_header_was_set(skb));
  56         hdr = (struct hsr_ethhdr_sp *) skb_mac_header(skb);
  57
  58         if (!ether_addr_equal(hdr->ethhdr.h_dest,
  59                               hsr->sup_multicast_addr))
  60                 return false;
  61
  62         if (get_hsr_stag_path(&hdr->hsr_sup) != 0x0f)
  63                 return false;
  64         if ((hdr->hsr_sup.HSR_TLV_Type != HSR_TLV_ANNOUNCE) &&
  65             (hdr->hsr_sup.HSR_TLV_Type != HSR_TLV_LIFE_CHECK))
  66                 return false;
  67         if (hdr->hsr_sup.HSR_TLV_Length != 12)
  68                 return false;
  69
  70         return true;
  71 }
  72
  73
  74 static struct sk_buff *create_stripped_skb(struct sk_buff *skb_in,
  75                                            struct hsr_frame_info *frame)
  76 {
  77         struct sk_buff *skb;
  78         int copylen;
  79         unsigned char *dst, *src;
  80
  81         skb_pull(skb_in, HSR_HLEN);
  82         skb = __pskb_copy(skb_in, skb_headroom(skb_in) - HSR_HLEN, GFP_ATOMIC);
  83         skb_push(skb_in, HSR_HLEN);
  84         if (skb == NULL)
  85                 return NULL;
  86
  87         skb_reset_mac_header(skb);
  88
  89         if (skb->ip_summed == CHECKSUM_PARTIAL)
  90                 skb->csum_start -= HSR_HLEN;
  91
  92         copylen = 2*ETH_ALEN;
  93         if (frame->is_vlan)
  94                 copylen += VLAN_HLEN;
  95         src = skb_mac_header(skb_in);
  96         dst = skb_mac_header(skb);
  97         memcpy(dst, src, copylen);
  98
  99         skb->protocol = eth_hdr(skb)->h_proto;
 100         return skb;
 101 }
 102
 103 static struct sk_buff *frame_get_stripped_skb(struct hsr_frame_info *frame,
 104                                               struct hsr_port *port)
 105 {
 106         if (!frame->skb_std)
 107                 frame->skb_std = create_stripped_skb(frame->skb_hsr, frame);
 108         return skb_clone(frame->skb_std, GFP_ATOMIC);
 109 }
 110
 111
 112 static void hsr_fill_tag(struct sk_buff *skb, struct hsr_frame_info *frame,
 113                          struct hsr_port *port)
 114 {
 115         struct hsr_ethhdr *hsr_ethhdr;
 116         int lane_id;
 117         int lsdu_size;
 118
 119         if (port->type == HSR_PT_SLAVE_A)
 120                 lane_id = 0;
 121         else
 122                 lane_id = 1;
 123
 124         lsdu_size = skb->len - 14;
 125         if (frame->is_vlan)
 126                 lsdu_size -= 4;
 127
 128         hsr_ethhdr = (struct hsr_ethhdr *) skb_mac_header(skb);
 129
 130         set_hsr_tag_path(&hsr_ethhdr->hsr_tag, lane_id);
 131         set_hsr_tag_LSDU_size(&hsr_ethhdr->hsr_tag, lsdu_size);
 132         hsr_ethhdr->hsr_tag.sequence_nr = htons(frame->sequence_nr);
 133         hsr_ethhdr->hsr_tag.encap_proto = hsr_ethhdr->ethhdr.h_proto;
 134         hsr_ethhdr->ethhdr.h_proto = htons(ETH_P_PRP);
 135 }
 136
 137 static struct sk_buff *create_tagged_skb(struct sk_buff *skb_o,
 138                                          struct hsr_frame_info *frame,
 139                                          struct hsr_port *port)
 140 {
 141         int movelen;
 142         unsigned char *dst, *src;
 143         struct sk_buff *skb;
 144
 145         /* Create the new skb with enough headroom to fit the HSR tag */
 146         skb = __pskb_copy(skb_o, skb_headroom(skb_o) + HSR_HLEN, GFP_ATOMIC);
 147         if (skb == NULL)
 148                 return NULL;
 149         skb_reset_mac_header(skb);
 150
 151         if (skb->ip_summed == CHECKSUM_PARTIAL)
 152                 skb->csum_start += HSR_HLEN;
 153
 154         movelen = ETH_HLEN;
 155         if (frame->is_vlan)
 156                 movelen += VLAN_HLEN;
 157
 158         src = skb_mac_header(skb);
 159         dst = skb_push(skb, HSR_HLEN);
 160         memmove(dst, src, movelen);
 161         skb_reset_mac_header(skb);
 162
 163         hsr_fill_tag(skb, frame, port);
 164
 165         return skb;
 166 }
 167
 168 /* If the original frame was an HSR tagged frame, just clone it to be sent
 169  * unchanged. Otherwise, create a private frame especially tagged for 'port'.
 170  */
 171 static struct sk_buff *frame_get_tagged_skb(struct hsr_frame_info *frame,
 172                                             struct hsr_port *port)
 173 {
 174         if (frame->skb_hsr)
 175                 return skb_clone(frame->skb_hsr, GFP_ATOMIC);
 176
 177         if ((port->type != HSR_PT_SLAVE_A) && (port->type != HSR_PT_SLAVE_B)) {
 178                 WARN_ONCE(1, "HSR: Bug: trying to create a tagged frame for a non-ring port");
 179                 return NULL;
 180         }
 181
 182         return create_tagged_skb(frame->skb_std, frame, port);
 183 }
 184
 185
 186 static void hsr_deliver_master(struct sk_buff *skb, struct net_device *dev,
 187                                struct hsr_node *node_src)
 188 {
 189         bool was_multicast_frame;
 190         int res;
 191
 192         was_multicast_frame = (skb->pkt_type == PACKET_MULTICAST);
 193         hsr_addr_subst_source(node_src, skb);
 194         skb_pull(skb, ETH_HLEN);
 195         res = netif_rx(skb);
 196         if (res == NET_RX_DROP) {
 197                 dev->stats.rx_dropped++;
 198         } else {
 199                 dev->stats.rx_packets++;
 200                 dev->stats.rx_bytes += skb->len;
 201                 if (was_multicast_frame)
 202                         dev->stats.multicast++;
 203         }
 204 }
 205
 206 static int hsr_xmit(struct sk_buff *skb, struct hsr_port *port,
 207                     struct hsr_frame_info *frame)
 208 {
 209         if (frame->port_rcv->type == HSR_PT_MASTER) {
 210                 hsr_addr_subst_dest(frame->node_src, skb, port);
 211
 212                 /* Address substitution (IEC62439-3 pp 26, 50): replace mac
 213                  * address of outgoing frame with that of the outgoing slave's.
 214                  */
 215                 ether_addr_copy(eth_hdr(skb)->h_source, port->dev->dev_addr);
 216         }
 217         return dev_queue_xmit(skb);
 218 }
 219
 220
 221 /* Forward the frame through all devices except:
 222  * - Back through the receiving device
 223  * - If it's a HSR frame: through a device where it has passed before
 224  * - To the local HSR master only if the frame is directly addressed to it, or
 225  *   a non-supervision multicast or broadcast frame.
 226  *
 227  * HSR slave devices should insert a HSR tag into the frame, or forward the
 228  * frame unchanged if it's already tagged. Interlink devices should strip HSR
 229  * tags if they're of the non-HSR type (but only after duplicate discard). The
 230  * master device always strips HSR tags.
 231  */
 232 static void hsr_forward_do(struct hsr_frame_info *frame)
 233 {
 234         struct hsr_port *port;
 235         struct sk_buff *skb;
 236
 237         hsr_for_each_port(frame->port_rcv->hsr, port) {
 238                 /* Don't send frame back the way it came */
 239                 if (port == frame->port_rcv)
 240                         continue;
 241
 242                 /* Don't deliver locally unless we should */
 243                 if ((port->type == HSR_PT_MASTER) && !frame->is_local_dest)
 244                         continue;
 245
 246                 /* Deliver frames directly addressed to us to master only */
 247                 if ((port->type != HSR_PT_MASTER) && frame->is_local_exclusive)
 248                         continue;
 249
 250                 /* Don't send frame over port where it has been sent before */
 251                 if (hsr_register_frame_out(port, frame->node_src,
 252                                            frame->sequence_nr))
 253                         continue;
 254
 255                 if (frame->is_supervision && (port->type == HSR_PT_MASTER)) {
 256                         hsr_handle_sup_frame(frame->skb_hsr,
 257                                              frame->node_src,
 258                                              frame->port_rcv);
 259                         continue;
 260                 }
 261
 262                 if (port->type != HSR_PT_MASTER)
 263                         skb = frame_get_tagged_skb(frame, port);
 264                 else
 265                         skb = frame_get_stripped_skb(frame, port);
 266                 if (skb == NULL) {
 267                         /* FIXME: Record the dropped frame? */
 268                         continue;
 269                 }
 270
 271                 skb->dev = port->dev;
 272                 if (port->type == HSR_PT_MASTER)
 273                         hsr_deliver_master(skb, port->dev, frame->node_src);
 274                 else
 275                         hsr_xmit(skb, port, frame);
 276         }
 277 }
 278
 279
 280 static void check_local_dest(struct hsr_priv *hsr, struct sk_buff *skb,
 281                              struct hsr_frame_info *frame)
 282 {
 283         struct net_device *master_dev;
 284
 285         master_dev = hsr_port_get_hsr(hsr, HSR_PT_MASTER)->dev;
 286
 287         if (hsr_addr_is_self(hsr, eth_hdr(skb)->h_dest)) {
 288                 frame->is_local_exclusive = true;
 289                 skb->pkt_type = PACKET_HOST;
 290         } else {
 291                 frame->is_local_exclusive = false;
 292         }
 293
 294         if ((skb->pkt_type == PACKET_HOST) ||
 295             (skb->pkt_type == PACKET_MULTICAST) ||
 296             (skb->pkt_type == PACKET_BROADCAST)) {
 297                 frame->is_local_dest = true;
 298         } else {
 299                 frame->is_local_dest = false;
 300         }
 301 }
 302
 303
 304 static int hsr_fill_frame_info(struct hsr_frame_info *frame,
 305                                struct sk_buff *skb, struct hsr_port *port)
 306 {
 307         struct ethhdr *ethhdr;
 308         unsigned long irqflags;
 309
 310         frame->is_supervision = is_supervision_frame(port->hsr, skb);
 311         frame->node_src = hsr_get_node(&port->hsr->node_db, skb,
 312                                        frame->is_supervision);
 313         if (frame->node_src == NULL)
 314                 return -1; /* Unknown node and !is_supervision, or no mem */
 315
 316         ethhdr = (struct ethhdr *) skb_mac_header(skb);
 317         frame->is_vlan = false;
 318         if (ethhdr->h_proto == htons(ETH_P_8021Q)) {
 319                 frame->is_vlan = true;
 320                 /* FIXME: */
 321                 WARN_ONCE(1, "HSR: VLAN not yet supported");
 322         }
 323         if (ethhdr->h_proto == htons(ETH_P_PRP)) {
 324                 frame->skb_std = NULL;
 325                 frame->skb_hsr = skb;
 326                 frame->sequence_nr = hsr_get_skb_sequence_nr(skb);
 327         } else {
 328                 frame->skb_std = skb;
 329                 frame->skb_hsr = NULL;
 330                 /* Sequence nr for the master node */
 331                 spin_lock_irqsave(&port->hsr->seqnr_lock, irqflags);
 332                 frame->sequence_nr = port->hsr->sequence_nr;
 333                 port->hsr->sequence_nr++;
 334                 spin_unlock_irqrestore(&port->hsr->seqnr_lock, irqflags);
 335         }
 336
 337         frame->port_rcv = port;
 338         check_local_dest(port->hsr, skb, frame);
 339
 340         return 0;
 341 }
 342
 343 /* Must be called holding rcu read lock (because of the port parameter) */
 344 void hsr_forward_skb(struct sk_buff *skb, struct hsr_port *port)
 345 {
 346         struct hsr_frame_info frame;
 347
 348         if (skb_mac_header(skb) != skb->data) {
 349                 WARN_ONCE(1, "%s:%d: Malformed frame (port_src %s)\n",
 350                           __FILE__, __LINE__, port->dev->name);
 351                 goto out_drop;
 352         }
 353
 354         if (hsr_fill_frame_info(&frame, skb, port) < 0)
 355                 goto out_drop;
 356         hsr_register_frame_in(frame.node_src, port, frame.sequence_nr);
 357         hsr_forward_do(&frame);
 358
 359         if (frame.skb_hsr != NULL)
 360                 kfree_skb(frame.skb_hsr);
 361         if (frame.skb_std != NULL)
 362                 kfree_skb(frame.skb_std);
 363         return;
 364
 365 out_drop:
 366         port->dev->stats.tx_dropped++;
 367         kfree_skb(skb);
 368 }