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