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