drivers/net/wan/hdlc_x25.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Generic HDLC support routines for Linux
   4  * X.25 support
   5  *
   6  * Copyright (C) 1999 - 2006 Krzysztof Halasa <khc@pm.waw.pl>
   7  */
   8
   9 #include <linux/errno.h>
  10 #include <linux/gfp.h>
  11 #include <linux/hdlc.h>
  12 #include <linux/if_arp.h>
  13 #include <linux/inetdevice.h>
  14 #include <linux/init.h>
  15 #include <linux/kernel.h>
  16 #include <linux/lapb.h>
  17 #include <linux/module.h>
  18 #include <linux/pkt_sched.h>
  19 #include <linux/poll.h>
  20 #include <linux/rtnetlink.h>
  21 #include <linux/skbuff.h>
  22 #include <net/x25device.h>
  23
  24 struct x25_state {
  25         x25_hdlc_proto settings;
  26         bool up;
  27         spinlock_t up_lock; /* Protects "up" */
  28         struct sk_buff_head rx_queue;
  29         struct tasklet_struct rx_tasklet;
  30 };
  31
  32 static int x25_ioctl(struct net_device *dev, struct ifreq *ifr);
  33
  34 static struct x25_state *state(hdlc_device *hdlc)
  35 {
  36         return hdlc->state;
  37 }
  38
  39 static void x25_rx_queue_kick(struct tasklet_struct *t)
  40 {
  41         struct x25_state *x25st = from_tasklet(x25st, t, rx_tasklet);
  42         struct sk_buff *skb = skb_dequeue(&x25st->rx_queue);
  43
  44         while (skb) {
  45                 netif_receive_skb_core(skb);
  46                 skb = skb_dequeue(&x25st->rx_queue);
  47         }
  48 }
  49
  50 /* These functions are callbacks called by LAPB layer */
  51
  52 static void x25_connect_disconnect(struct net_device *dev, int reason, int code)
  53 {
  54         struct x25_state *x25st = state(dev_to_hdlc(dev));
  55         struct sk_buff *skb;
  56         unsigned char *ptr;
  57
  58         skb = __dev_alloc_skb(1, GFP_ATOMIC | __GFP_NOMEMALLOC);
  59         if (!skb) {
  60                 netdev_err(dev, "out of memory\n");
  61                 return;
  62         }
  63
  64         ptr = skb_put(skb, 1);
  65         *ptr = code;
  66
  67         skb->protocol = x25_type_trans(skb, dev);
  68
  69         skb_queue_tail(&x25st->rx_queue, skb);
  70         tasklet_schedule(&x25st->rx_tasklet);
  71 }
  72
  73
  74
  75 static void x25_connected(struct net_device *dev, int reason)
  76 {
  77         x25_connect_disconnect(dev, reason, X25_IFACE_CONNECT);
  78 }
  79
  80
  81
  82 static void x25_disconnected(struct net_device *dev, int reason)
  83 {
  84         x25_connect_disconnect(dev, reason, X25_IFACE_DISCONNECT);
  85 }
  86
  87
  88
  89 static int x25_data_indication(struct net_device *dev, struct sk_buff *skb)
  90 {
  91         struct x25_state *x25st = state(dev_to_hdlc(dev));
  92         unsigned char *ptr;
  93
  94         if (skb_cow(skb, 1)) {
  95                 kfree_skb(skb);
  96                 return NET_RX_DROP;
  97         }
  98
  99         skb_push(skb, 1);
 100
 101         ptr  = skb->data;
 102         *ptr = X25_IFACE_DATA;
 103
 104         skb->protocol = x25_type_trans(skb, dev);
 105
 106         skb_queue_tail(&x25st->rx_queue, skb);
 107         tasklet_schedule(&x25st->rx_tasklet);
 108         return NET_RX_SUCCESS;
 109 }
 110
 111
 112
 113 static void x25_data_transmit(struct net_device *dev, struct sk_buff *skb)
 114 {
 115         hdlc_device *hdlc = dev_to_hdlc(dev);
 116
 117         skb_reset_network_header(skb);
 118         skb->protocol = hdlc_type_trans(skb, dev);
 119
 120         if (dev_nit_active(dev))
 121                 dev_queue_xmit_nit(skb, dev);
 122
 123         hdlc->xmit(skb, dev); /* Ignore return value :-( */
 124 }
 125
 126
 127
 128 static netdev_tx_t x25_xmit(struct sk_buff *skb, struct net_device *dev)
 129 {
 130         hdlc_device *hdlc = dev_to_hdlc(dev);
 131         struct x25_state *x25st = state(hdlc);
 132         int result;
 133
 134         /* There should be a pseudo header of 1 byte added by upper layers.
 135          * Check to make sure it is there before reading it.
 136          */
 137         if (skb->len < 1) {
 138                 kfree_skb(skb);
 139                 return NETDEV_TX_OK;
 140         }
 141
 142         spin_lock_bh(&x25st->up_lock);
 143         if (!x25st->up) {
 144                 spin_unlock_bh(&x25st->up_lock);
 145                 kfree_skb(skb);
 146                 return NETDEV_TX_OK;
 147         }
 148
 149         switch (skb->data[0]) {
 150         case X25_IFACE_DATA:    /* Data to be transmitted */
 151                 skb_pull(skb, 1);
 152                 if ((result = lapb_data_request(dev, skb)) != LAPB_OK)
 153                         dev_kfree_skb(skb);
 154                 spin_unlock_bh(&x25st->up_lock);
 155                 return NETDEV_TX_OK;
 156
 157         case X25_IFACE_CONNECT:
 158                 if ((result = lapb_connect_request(dev))!= LAPB_OK) {
 159                         if (result == LAPB_CONNECTED)
 160                                 /* Send connect confirm. msg to level 3 */
 161                                 x25_connected(dev, 0);
 162                         else
 163                                 netdev_err(dev, "LAPB connect request failed, error code = %i\n",
 164                                            result);
 165                 }
 166                 break;
 167
 168         case X25_IFACE_DISCONNECT:
 169                 if ((result = lapb_disconnect_request(dev)) != LAPB_OK) {
 170                         if (result == LAPB_NOTCONNECTED)
 171                                 /* Send disconnect confirm. msg to level 3 */
 172                                 x25_disconnected(dev, 0);
 173                         else
 174                                 netdev_err(dev, "LAPB disconnect request failed, error code = %i\n",
 175                                            result);
 176                 }
 177                 break;
 178
 179         default:                /* to be defined */
 180                 break;
 181         }
 182
 183         spin_unlock_bh(&x25st->up_lock);
 184         dev_kfree_skb(skb);
 185         return NETDEV_TX_OK;
 186 }
 187
 188
 189
 190 static int x25_open(struct net_device *dev)
 191 {
 192         static const struct lapb_register_struct cb = {
 193                 .connect_confirmation = x25_connected,
 194                 .connect_indication = x25_connected,
 195                 .disconnect_confirmation = x25_disconnected,
 196                 .disconnect_indication = x25_disconnected,
 197                 .data_indication = x25_data_indication,
 198                 .data_transmit = x25_data_transmit,
 199         };
 200         hdlc_device *hdlc = dev_to_hdlc(dev);
 201         struct x25_state *x25st = state(hdlc);
 202         struct lapb_parms_struct params;
 203         int result;
 204
 205         result = lapb_register(dev, &cb);
 206         if (result != LAPB_OK)
 207                 return -ENOMEM;
 208
 209         result = lapb_getparms(dev, &params);
 210         if (result != LAPB_OK)
 211                 return -EINVAL;
 212
 213         if (state(hdlc)->settings.dce)
 214                 params.mode = params.mode | LAPB_DCE;
 215
 216         if (state(hdlc)->settings.modulo == 128)
 217                 params.mode = params.mode | LAPB_EXTENDED;
 218
 219         params.window = state(hdlc)->settings.window;
 220         params.t1 = state(hdlc)->settings.t1;
 221         params.t2 = state(hdlc)->settings.t2;
 222         params.n2 = state(hdlc)->settings.n2;
 223
 224         result = lapb_setparms(dev, &params);
 225         if (result != LAPB_OK)
 226                 return -EINVAL;
 227
 228         spin_lock_bh(&x25st->up_lock);
 229         x25st->up = true;
 230         spin_unlock_bh(&x25st->up_lock);
 231
 232         return 0;
 233 }
 234
 235
 236
 237 static void x25_close(struct net_device *dev)
 238 {
 239         hdlc_device *hdlc = dev_to_hdlc(dev);
 240         struct x25_state *x25st = state(hdlc);
 241
 242         spin_lock_bh(&x25st->up_lock);
 243         x25st->up = false;
 244         spin_unlock_bh(&x25st->up_lock);
 245
 246         lapb_unregister(dev);
 247         tasklet_kill(&x25st->rx_tasklet);
 248 }
 249
 250
 251
 252 static int x25_rx(struct sk_buff *skb)
 253 {
 254         struct net_device *dev = skb->dev;
 255         hdlc_device *hdlc = dev_to_hdlc(dev);
 256         struct x25_state *x25st = state(hdlc);
 257
 258         if ((skb = skb_share_check(skb, GFP_ATOMIC)) == NULL) {
 259                 dev->stats.rx_dropped++;
 260                 return NET_RX_DROP;
 261         }
 262
 263         spin_lock_bh(&x25st->up_lock);
 264         if (!x25st->up) {
 265                 spin_unlock_bh(&x25st->up_lock);
 266                 kfree_skb(skb);
 267                 dev->stats.rx_dropped++;
 268                 return NET_RX_DROP;
 269         }
 270
 271         if (lapb_data_received(dev, skb) == LAPB_OK) {
 272                 spin_unlock_bh(&x25st->up_lock);
 273                 return NET_RX_SUCCESS;
 274         }
 275
 276         spin_unlock_bh(&x25st->up_lock);
 277         dev->stats.rx_errors++;
 278         dev_kfree_skb_any(skb);
 279         return NET_RX_DROP;
 280 }
 281
 282
 283 static struct hdlc_proto proto = {
 284         .open           = x25_open,
 285         .close          = x25_close,
 286         .ioctl          = x25_ioctl,
 287         .netif_rx       = x25_rx,
 288         .xmit           = x25_xmit,
 289         .module         = THIS_MODULE,
 290 };
 291
 292
 293 static int x25_ioctl(struct net_device *dev, struct ifreq *ifr)
 294 {
 295         x25_hdlc_proto __user *x25_s = ifr->ifr_settings.ifs_ifsu.x25;
 296         const size_t size = sizeof(x25_hdlc_proto);
 297         hdlc_device *hdlc = dev_to_hdlc(dev);
 298         x25_hdlc_proto new_settings;
 299         int result;
 300
 301         switch (ifr->ifr_settings.type) {
 302         case IF_GET_PROTO:
 303                 if (dev_to_hdlc(dev)->proto != &proto)
 304                         return -EINVAL;
 305                 ifr->ifr_settings.type = IF_PROTO_X25;
 306                 if (ifr->ifr_settings.size < size) {
 307                         ifr->ifr_settings.size = size; /* data size wanted */
 308                         return -ENOBUFS;
 309                 }
 310                 if (copy_to_user(x25_s, &state(hdlc)->settings, size))
 311                         return -EFAULT;
 312                 return 0;
 313
 314         case IF_PROTO_X25:
 315                 if (!capable(CAP_NET_ADMIN))
 316                         return -EPERM;
 317
 318                 if (dev->flags & IFF_UP)
 319                         return -EBUSY;
 320
 321                 /* backward compatibility */
 322                 if (ifr->ifr_settings.size == 0) {
 323                         new_settings.dce = 0;
 324                         new_settings.modulo = 8;
 325                         new_settings.window = 7;
 326                         new_settings.t1 = 3;
 327                         new_settings.t2 = 1;
 328                         new_settings.n2 = 10;
 329                 }
 330                 else {
 331                         if (copy_from_user(&new_settings, x25_s, size))
 332                                 return -EFAULT;
 333
 334                         if ((new_settings.dce != 0 &&
 335                         new_settings.dce != 1) ||
 336                         (new_settings.modulo != 8 &&
 337                         new_settings.modulo != 128) ||
 338                         new_settings.window < 1 ||
 339                         (new_settings.modulo == 8 &&
 340                         new_settings.window > 7) ||
 341                         (new_settings.modulo == 128 &&
 342                         new_settings.window > 127) ||
 343                         new_settings.t1 < 1 ||
 344                         new_settings.t1 > 255 ||
 345                         new_settings.t2 < 1 ||
 346                         new_settings.t2 > 255 ||
 347                         new_settings.n2 < 1 ||
 348                         new_settings.n2 > 255)
 349                                 return -EINVAL;
 350                 }
 351
 352                 result=hdlc->attach(dev, ENCODING_NRZ,PARITY_CRC16_PR1_CCITT);
 353                 if (result)
 354                         return result;
 355
 356                 if ((result = attach_hdlc_protocol(dev, &proto,
 357                                                    sizeof(struct x25_state))))
 358                         return result;
 359
 360                 memcpy(&state(hdlc)->settings, &new_settings, size);
 361                 state(hdlc)->up = false;
 362                 spin_lock_init(&state(hdlc)->up_lock);
 363                 skb_queue_head_init(&state(hdlc)->rx_queue);
 364                 tasklet_setup(&state(hdlc)->rx_tasklet, x25_rx_queue_kick);
 365
 366                 /* There's no header_ops so hard_header_len should be 0. */
 367                 dev->hard_header_len = 0;
 368                 /* When transmitting data:
 369                  * first we'll remove a pseudo header of 1 byte,
 370                  * then we'll prepend an LAPB header of at most 3 bytes.
 371                  */
 372                 dev->needed_headroom = 3 - 1;
 373
 374                 dev->type = ARPHRD_X25;
 375                 call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
 376                 netif_dormant_off(dev);
 377                 return 0;
 378         }
 379
 380         return -EINVAL;
 381 }
 382
 383
 384 static int __init mod_init(void)
 385 {
 386         register_hdlc_protocol(&proto);
 387         return 0;
 388 }
 389
 390
 391
 392 static void __exit mod_exit(void)
 393 {
 394         unregister_hdlc_protocol(&proto);
 395 }
 396
 397
 398 module_init(mod_init);
 399 module_exit(mod_exit);
 400
 401 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 402 MODULE_DESCRIPTION("X.25 protocol support for generic HDLC");
 403 MODULE_LICENSE("GPL v2");