drivers/net/wan/hdlc_cisco.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Generic HDLC support routines for Linux
   4  * Cisco HDLC support
   5  *
   6  * Copyright (C) 2000 - 2006 Krzysztof Halasa <khc@pm.waw.pl>
   7  */
   8
   9 #include <linux/errno.h>
  10 #include <linux/hdlc.h>
  11 #include <linux/if_arp.h>
  12 #include <linux/inetdevice.h>
  13 #include <linux/init.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/pkt_sched.h>
  17 #include <linux/poll.h>
  18 #include <linux/rtnetlink.h>
  19 #include <linux/skbuff.h>
  20
  21 #undef DEBUG_HARD_HEADER
  22
  23 #define CISCO_MULTICAST         0x8F    /* Cisco multicast address */
  24 #define CISCO_UNICAST           0x0F    /* Cisco unicast address */
  25 #define CISCO_KEEPALIVE         0x8035  /* Cisco keepalive protocol */
  26 #define CISCO_SYS_INFO          0x2000  /* Cisco interface/system info */
  27 #define CISCO_ADDR_REQ          0       /* Cisco address request */
  28 #define CISCO_ADDR_REPLY        1       /* Cisco address reply */
  29 #define CISCO_KEEPALIVE_REQ     2       /* Cisco keepalive request */
  30
  31 struct hdlc_header {
  32         u8 address;
  33         u8 control;
  34         __be16 protocol;
  35 } __packed;
  36
  37 struct cisco_packet {
  38         __be32 type;            /* code */
  39         __be32 par1;
  40         __be32 par2;
  41         __be16 rel;             /* reliability */
  42         __be32 time;
  43 } __packed;
  44 #define CISCO_PACKET_LEN        18
  45 #define CISCO_BIG_PACKET_LEN    20
  46
  47 struct cisco_state {
  48         cisco_proto settings;
  49
  50         struct timer_list timer;
  51         struct net_device *dev;
  52         spinlock_t lock;
  53         unsigned long last_poll;
  54         int up;
  55         u32 txseq; /* TX sequence number, 0 = none */
  56         u32 rxseq; /* RX sequence number */
  57 };
  58
  59 static int cisco_ioctl(struct net_device *dev, struct if_settings *ifs);
  60
  61 static inline struct cisco_state *state(hdlc_device *hdlc)
  62 {
  63         return (struct cisco_state *)hdlc->state;
  64 }
  65
  66 static int cisco_hard_header(struct sk_buff *skb, struct net_device *dev,
  67                              u16 type, const void *daddr, const void *saddr,
  68                              unsigned int len)
  69 {
  70         struct hdlc_header *data;
  71 #ifdef DEBUG_HARD_HEADER
  72         netdev_dbg(dev, "%s called\n", __func__);
  73 #endif
  74
  75         skb_push(skb, sizeof(struct hdlc_header));
  76         data = (struct hdlc_header *)skb->data;
  77         if (type == CISCO_KEEPALIVE)
  78                 data->address = CISCO_MULTICAST;
  79         else
  80                 data->address = CISCO_UNICAST;
  81         data->control = 0;
  82         data->protocol = htons(type);
  83
  84         return sizeof(struct hdlc_header);
  85 }
  86
  87 static void cisco_keepalive_send(struct net_device *dev, u32 type,
  88                                  __be32 par1, __be32 par2)
  89 {
  90         struct sk_buff *skb;
  91         struct cisco_packet *data;
  92
  93         skb = dev_alloc_skb(sizeof(struct hdlc_header) +
  94                             sizeof(struct cisco_packet));
  95         if (!skb)
  96                 return;
  97
  98         skb_reserve(skb, 4);
  99         cisco_hard_header(skb, dev, CISCO_KEEPALIVE, NULL, NULL, 0);
 100         data = (struct cisco_packet *)(skb->data + 4);
 101
 102         data->type = htonl(type);
 103         data->par1 = par1;
 104         data->par2 = par2;
 105         data->rel = cpu_to_be16(0xFFFF);
 106         /* we will need do_div here if 1000 % HZ != 0 */
 107         data->time = htonl((jiffies - INITIAL_JIFFIES) * (1000 / HZ));
 108
 109         skb_put(skb, sizeof(struct cisco_packet));
 110         skb->priority = TC_PRIO_CONTROL;
 111         skb->dev = dev;
 112         skb->protocol = htons(ETH_P_HDLC);
 113         skb_reset_network_header(skb);
 114
 115         dev_queue_xmit(skb);
 116 }
 117
 118 static __be16 cisco_type_trans(struct sk_buff *skb, struct net_device *dev)
 119 {
 120         struct hdlc_header *data = (struct hdlc_header *)skb->data;
 121
 122         if (skb->len < sizeof(struct hdlc_header))
 123                 return cpu_to_be16(ETH_P_HDLC);
 124
 125         if (data->address != CISCO_MULTICAST &&
 126             data->address != CISCO_UNICAST)
 127                 return cpu_to_be16(ETH_P_HDLC);
 128
 129         switch (data->protocol) {
 130         case cpu_to_be16(ETH_P_IP):
 131         case cpu_to_be16(ETH_P_IPX):
 132         case cpu_to_be16(ETH_P_IPV6):
 133                 skb_pull(skb, sizeof(struct hdlc_header));
 134                 return data->protocol;
 135         default:
 136                 return cpu_to_be16(ETH_P_HDLC);
 137         }
 138 }
 139
 140 static int cisco_rx(struct sk_buff *skb)
 141 {
 142         struct net_device *dev = skb->dev;
 143         hdlc_device *hdlc = dev_to_hdlc(dev);
 144         struct cisco_state *st = state(hdlc);
 145         struct hdlc_header *data = (struct hdlc_header *)skb->data;
 146         struct cisco_packet *cisco_data;
 147         struct in_device *in_dev;
 148         __be32 addr, mask;
 149         u32 ack;
 150
 151         if (skb->len < sizeof(struct hdlc_header))
 152                 goto rx_error;
 153
 154         if (data->address != CISCO_MULTICAST &&
 155             data->address != CISCO_UNICAST)
 156                 goto rx_error;
 157
 158         switch (ntohs(data->protocol)) {
 159         case CISCO_SYS_INFO:
 160                 /* Packet is not needed, drop it. */
 161                 dev_kfree_skb_any(skb);
 162                 return NET_RX_SUCCESS;
 163
 164         case CISCO_KEEPALIVE:
 165                 if ((skb->len != sizeof(struct hdlc_header) +
 166                      CISCO_PACKET_LEN) &&
 167                     (skb->len != sizeof(struct hdlc_header) +
 168                      CISCO_BIG_PACKET_LEN)) {
 169                         netdev_info(dev, "Invalid length of Cisco control packet (%d bytes)\n",
 170                                     skb->len);
 171                         goto rx_error;
 172                 }
 173
 174                 cisco_data = (struct cisco_packet *)(skb->data + sizeof
 175                                                     (struct hdlc_header));
 176
 177                 switch (ntohl(cisco_data->type)) {
 178                 case CISCO_ADDR_REQ: /* Stolen from syncppp.c :-) */
 179                         rcu_read_lock();
 180                         in_dev = __in_dev_get_rcu(dev);
 181                         addr = 0;
 182                         mask = ~cpu_to_be32(0); /* is the mask correct? */
 183
 184                         if (in_dev != NULL) {
 185                                 const struct in_ifaddr *ifa;
 186
 187                                 in_dev_for_each_ifa_rcu(ifa, in_dev) {
 188                                         if (strcmp(dev->name,
 189                                                    ifa->ifa_label) == 0) {
 190                                                 addr = ifa->ifa_local;
 191                                                 mask = ifa->ifa_mask;
 192                                                 break;
 193                                         }
 194                                 }
 195
 196                                 cisco_keepalive_send(dev, CISCO_ADDR_REPLY,
 197                                                      addr, mask);
 198                         }
 199                         rcu_read_unlock();
 200                         dev_kfree_skb_any(skb);
 201                         return NET_RX_SUCCESS;
 202
 203                 case CISCO_ADDR_REPLY:
 204                         netdev_info(dev, "Unexpected Cisco IP address reply\n");
 205                         goto rx_error;
 206
 207                 case CISCO_KEEPALIVE_REQ:
 208                         spin_lock(&st->lock);
 209                         st->rxseq = ntohl(cisco_data->par1);
 210                         ack = ntohl(cisco_data->par2);
 211                         if (ack && (ack == st->txseq ||
 212                                     /* our current REQ may be in transit */
 213                                     ack == st->txseq - 1)) {
 214                                 st->last_poll = jiffies;
 215                                 if (!st->up) {
 216                                         u32 sec, min, hrs, days;
 217
 218                                         sec = ntohl(cisco_data->time) / 1000;
 219                                         min = sec / 60; sec -= min * 60;
 220                                         hrs = min / 60; min -= hrs * 60;
 221                                         days = hrs / 24; hrs -= days * 24;
 222                                         netdev_info(dev, "Link up (peer uptime %ud%uh%um%us)\n",
 223                                                     days, hrs, min, sec);
 224                                         netif_dormant_off(dev);
 225                                         st->up = 1;
 226                                 }
 227                         }
 228                         spin_unlock(&st->lock);
 229
 230                         dev_kfree_skb_any(skb);
 231                         return NET_RX_SUCCESS;
 232                 } /* switch (keepalive type) */
 233         } /* switch (protocol) */
 234
 235         netdev_info(dev, "Unsupported protocol %x\n", ntohs(data->protocol));
 236         dev_kfree_skb_any(skb);
 237         return NET_RX_DROP;
 238
 239 rx_error:
 240         dev->stats.rx_errors++; /* Mark error */
 241         dev_kfree_skb_any(skb);
 242         return NET_RX_DROP;
 243 }
 244
 245 static void cisco_timer(struct timer_list *t)
 246 {
 247         struct cisco_state *st = from_timer(st, t, timer);
 248         struct net_device *dev = st->dev;
 249
 250         spin_lock(&st->lock);
 251         if (st->up &&
 252             time_after(jiffies, st->last_poll + st->settings.timeout * HZ)) {
 253                 st->up = 0;
 254                 netdev_info(dev, "Link down\n");
 255                 netif_dormant_on(dev);
 256         }
 257
 258         cisco_keepalive_send(dev, CISCO_KEEPALIVE_REQ, htonl(++st->txseq),
 259                              htonl(st->rxseq));
 260         spin_unlock(&st->lock);
 261
 262         st->timer.expires = jiffies + st->settings.interval * HZ;
 263         add_timer(&st->timer);
 264 }
 265
 266 static void cisco_start(struct net_device *dev)
 267 {
 268         hdlc_device *hdlc = dev_to_hdlc(dev);
 269         struct cisco_state *st = state(hdlc);
 270         unsigned long flags;
 271
 272         spin_lock_irqsave(&st->lock, flags);
 273         st->up = st->txseq = st->rxseq = 0;
 274         spin_unlock_irqrestore(&st->lock, flags);
 275
 276         st->dev = dev;
 277         timer_setup(&st->timer, cisco_timer, 0);
 278         st->timer.expires = jiffies + HZ; /* First poll after 1 s */
 279         add_timer(&st->timer);
 280 }
 281
 282 static void cisco_stop(struct net_device *dev)
 283 {
 284         hdlc_device *hdlc = dev_to_hdlc(dev);
 285         struct cisco_state *st = state(hdlc);
 286         unsigned long flags;
 287
 288         del_timer_sync(&st->timer);
 289
 290         spin_lock_irqsave(&st->lock, flags);
 291         netif_dormant_on(dev);
 292         st->up = st->txseq = 0;
 293         spin_unlock_irqrestore(&st->lock, flags);
 294 }
 295
 296 static struct hdlc_proto proto = {
 297         .start          = cisco_start,
 298         .stop           = cisco_stop,
 299         .type_trans     = cisco_type_trans,
 300         .ioctl          = cisco_ioctl,
 301         .netif_rx       = cisco_rx,
 302         .module         = THIS_MODULE,
 303 };
 304
 305 static const struct header_ops cisco_header_ops = {
 306         .create = cisco_hard_header,
 307 };
 308
 309 static int cisco_ioctl(struct net_device *dev, struct if_settings *ifs)
 310 {
 311         cisco_proto __user *cisco_s = ifs->ifs_ifsu.cisco;
 312         const size_t size = sizeof(cisco_proto);
 313         cisco_proto new_settings;
 314         hdlc_device *hdlc = dev_to_hdlc(dev);
 315         int result;
 316
 317         switch (ifs->type) {
 318         case IF_GET_PROTO:
 319                 if (dev_to_hdlc(dev)->proto != &proto)
 320                         return -EINVAL;
 321                 ifs->type = IF_PROTO_CISCO;
 322                 if (ifs->size < size) {
 323                         ifs->size = size; /* data size wanted */
 324                         return -ENOBUFS;
 325                 }
 326                 if (copy_to_user(cisco_s, &state(hdlc)->settings, size))
 327                         return -EFAULT;
 328                 return 0;
 329
 330         case IF_PROTO_CISCO:
 331                 if (!capable(CAP_NET_ADMIN))
 332                         return -EPERM;
 333
 334                 if (dev->flags & IFF_UP)
 335                         return -EBUSY;
 336
 337                 if (copy_from_user(&new_settings, cisco_s, size))
 338                         return -EFAULT;
 339
 340                 if (new_settings.interval < 1 ||
 341                     new_settings.timeout < 2)
 342                         return -EINVAL;
 343
 344                 result = hdlc->attach(dev, ENCODING_NRZ,
 345                                       PARITY_CRC16_PR1_CCITT);
 346                 if (result)
 347                         return result;
 348
 349                 result = attach_hdlc_protocol(dev, &proto,
 350                                               sizeof(struct cisco_state));
 351                 if (result)
 352                         return result;
 353
 354                 memcpy(&state(hdlc)->settings, &new_settings, size);
 355                 spin_lock_init(&state(hdlc)->lock);
 356                 dev->header_ops = &cisco_header_ops;
 357                 dev->hard_header_len = sizeof(struct hdlc_header);
 358                 dev->type = ARPHRD_CISCO;
 359                 call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
 360                 netif_dormant_on(dev);
 361                 return 0;
 362         }
 363
 364         return -EINVAL;
 365 }
 366
 367 static int __init hdlc_cisco_init(void)
 368 {
 369         register_hdlc_protocol(&proto);
 370         return 0;
 371 }
 372
 373 static void __exit hdlc_cisco_exit(void)
 374 {
 375         unregister_hdlc_protocol(&proto);
 376 }
 377
 378 module_init(hdlc_cisco_init);
 379 module_exit(hdlc_cisco_exit);
 380
 381 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 382 MODULE_DESCRIPTION("Cisco HDLC protocol support for generic HDLC");
 383 MODULE_LICENSE("GPL v2");