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 if_settings *ifs);
  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                 return;
  61
  62         ptr = skb_put(skb, 1);
  63         *ptr = code;
  64
  65         skb->protocol = x25_type_trans(skb, dev);
  66
  67         skb_queue_tail(&x25st->rx_queue, skb);
  68         tasklet_schedule(&x25st->rx_tasklet);
  69 }
  70
  71 static void x25_connected(struct net_device *dev, int reason)
  72 {
  73         x25_connect_disconnect(dev, reason, X25_IFACE_CONNECT);
  74 }
  75
  76 static void x25_disconnected(struct net_device *dev, int reason)
  77 {
  78         x25_connect_disconnect(dev, reason, X25_IFACE_DISCONNECT);
  79 }
  80
  81 static int x25_data_indication(struct net_device *dev, struct sk_buff *skb)
  82 {
  83         struct x25_state *x25st = state(dev_to_hdlc(dev));
  84         unsigned char *ptr;
  85
  86         if (skb_cow(skb, 1)) {
  87                 kfree_skb(skb);
  88                 return NET_RX_DROP;
  89         }
  90
  91         skb_push(skb, 1);
  92
  93         ptr  = skb->data;
  94         *ptr = X25_IFACE_DATA;
  95
  96         skb->protocol = x25_type_trans(skb, dev);
  97
  98         skb_queue_tail(&x25st->rx_queue, skb);
  99         tasklet_schedule(&x25st->rx_tasklet);
 100         return NET_RX_SUCCESS;
 101 }
 102
 103 static void x25_data_transmit(struct net_device *dev, struct sk_buff *skb)
 104 {
 105         hdlc_device *hdlc = dev_to_hdlc(dev);
 106
 107         skb_reset_network_header(skb);
 108         skb->protocol = hdlc_type_trans(skb, dev);
 109
 110         if (dev_nit_active(dev))
 111                 dev_queue_xmit_nit(skb, dev);
 112
 113         hdlc->xmit(skb, dev); /* Ignore return value :-( */
 114 }
 115
 116 static netdev_tx_t x25_xmit(struct sk_buff *skb, struct net_device *dev)
 117 {
 118         hdlc_device *hdlc = dev_to_hdlc(dev);
 119         struct x25_state *x25st = state(hdlc);
 120         int result;
 121
 122         /* There should be a pseudo header of 1 byte added by upper layers.
 123          * Check to make sure it is there before reading it.
 124          */
 125         if (skb->len < 1) {
 126                 kfree_skb(skb);
 127                 return NETDEV_TX_OK;
 128         }
 129
 130         spin_lock_bh(&x25st->up_lock);
 131         if (!x25st->up) {
 132                 spin_unlock_bh(&x25st->up_lock);
 133                 kfree_skb(skb);
 134                 return NETDEV_TX_OK;
 135         }
 136
 137         switch (skb->data[0]) {
 138         case X25_IFACE_DATA:    /* Data to be transmitted */
 139                 skb_pull(skb, 1);
 140                 result = lapb_data_request(dev, skb);
 141                 if (result != LAPB_OK)
 142                         dev_kfree_skb(skb);
 143                 spin_unlock_bh(&x25st->up_lock);
 144                 return NETDEV_TX_OK;
 145
 146         case X25_IFACE_CONNECT:
 147                 result = lapb_connect_request(dev);
 148                 if (result != LAPB_OK) {
 149                         if (result == LAPB_CONNECTED)
 150                                 /* Send connect confirm. msg to level 3 */
 151                                 x25_connected(dev, 0);
 152                         else
 153                                 netdev_err(dev, "LAPB connect request failed, error code = %i\n",
 154                                            result);
 155                 }
 156                 break;
 157
 158         case X25_IFACE_DISCONNECT:
 159                 result = lapb_disconnect_request(dev);
 160                 if (result != LAPB_OK) {
 161                         if (result == LAPB_NOTCONNECTED)
 162                                 /* Send disconnect confirm. msg to level 3 */
 163                                 x25_disconnected(dev, 0);
 164                         else
 165                                 netdev_err(dev, "LAPB disconnect request failed, error code = %i\n",
 166                                            result);
 167                 }
 168                 break;
 169
 170         default:                /* to be defined */
 171                 break;
 172         }
 173
 174         spin_unlock_bh(&x25st->up_lock);
 175         dev_kfree_skb(skb);
 176         return NETDEV_TX_OK;
 177 }
 178
 179 static int x25_open(struct net_device *dev)
 180 {
 181         static const struct lapb_register_struct cb = {
 182                 .connect_confirmation = x25_connected,
 183                 .connect_indication = x25_connected,
 184                 .disconnect_confirmation = x25_disconnected,
 185                 .disconnect_indication = x25_disconnected,
 186                 .data_indication = x25_data_indication,
 187                 .data_transmit = x25_data_transmit,
 188         };
 189         hdlc_device *hdlc = dev_to_hdlc(dev);
 190         struct x25_state *x25st = state(hdlc);
 191         struct lapb_parms_struct params;
 192         int result;
 193
 194         result = lapb_register(dev, &cb);
 195         if (result != LAPB_OK)
 196                 return -ENOMEM;
 197
 198         result = lapb_getparms(dev, &params);
 199         if (result != LAPB_OK)
 200                 return -EINVAL;
 201
 202         if (state(hdlc)->settings.dce)
 203                 params.mode = params.mode | LAPB_DCE;
 204
 205         if (state(hdlc)->settings.modulo == 128)
 206                 params.mode = params.mode | LAPB_EXTENDED;
 207
 208         params.window = state(hdlc)->settings.window;
 209         params.t1 = state(hdlc)->settings.t1;
 210         params.t2 = state(hdlc)->settings.t2;
 211         params.n2 = state(hdlc)->settings.n2;
 212
 213         result = lapb_setparms(dev, &params);
 214         if (result != LAPB_OK)
 215                 return -EINVAL;
 216
 217         spin_lock_bh(&x25st->up_lock);
 218         x25st->up = true;
 219         spin_unlock_bh(&x25st->up_lock);
 220
 221         return 0;
 222 }
 223
 224 static void x25_close(struct net_device *dev)
 225 {
 226         hdlc_device *hdlc = dev_to_hdlc(dev);
 227         struct x25_state *x25st = state(hdlc);
 228
 229         spin_lock_bh(&x25st->up_lock);
 230         x25st->up = false;
 231         spin_unlock_bh(&x25st->up_lock);
 232
 233         lapb_unregister(dev);
 234         tasklet_kill(&x25st->rx_tasklet);
 235 }
 236
 237 static int x25_rx(struct sk_buff *skb)
 238 {
 239         struct net_device *dev = skb->dev;
 240         hdlc_device *hdlc = dev_to_hdlc(dev);
 241         struct x25_state *x25st = state(hdlc);
 242
 243         skb = skb_share_check(skb, GFP_ATOMIC);
 244         if (!skb) {
 245                 dev->stats.rx_dropped++;
 246                 return NET_RX_DROP;
 247         }
 248
 249         spin_lock_bh(&x25st->up_lock);
 250         if (!x25st->up) {
 251                 spin_unlock_bh(&x25st->up_lock);
 252                 kfree_skb(skb);
 253                 dev->stats.rx_dropped++;
 254                 return NET_RX_DROP;
 255         }
 256
 257         if (lapb_data_received(dev, skb) == LAPB_OK) {
 258                 spin_unlock_bh(&x25st->up_lock);
 259                 return NET_RX_SUCCESS;
 260         }
 261
 262         spin_unlock_bh(&x25st->up_lock);
 263         dev->stats.rx_errors++;
 264         dev_kfree_skb_any(skb);
 265         return NET_RX_DROP;
 266 }
 267
 268 static struct hdlc_proto proto = {
 269         .open           = x25_open,
 270         .close          = x25_close,
 271         .ioctl          = x25_ioctl,
 272         .netif_rx       = x25_rx,
 273         .xmit           = x25_xmit,
 274         .module         = THIS_MODULE,
 275 };
 276
 277 static int x25_ioctl(struct net_device *dev, struct if_settings *ifs)
 278 {
 279         x25_hdlc_proto __user *x25_s = ifs->ifs_ifsu.x25;
 280         const size_t size = sizeof(x25_hdlc_proto);
 281         hdlc_device *hdlc = dev_to_hdlc(dev);
 282         x25_hdlc_proto new_settings;
 283         int result;
 284
 285         switch (ifs->type) {
 286         case IF_GET_PROTO:
 287                 if (dev_to_hdlc(dev)->proto != &proto)
 288                         return -EINVAL;
 289                 ifs->type = IF_PROTO_X25;
 290                 if (ifs->size < size) {
 291                         ifs->size = size; /* data size wanted */
 292                         return -ENOBUFS;
 293                 }
 294                 if (copy_to_user(x25_s, &state(hdlc)->settings, size))
 295                         return -EFAULT;
 296                 return 0;
 297
 298         case IF_PROTO_X25:
 299                 if (!capable(CAP_NET_ADMIN))
 300                         return -EPERM;
 301
 302                 if (dev->flags & IFF_UP)
 303                         return -EBUSY;
 304
 305                 /* backward compatibility */
 306                 if (ifs->size == 0) {
 307                         new_settings.dce = 0;
 308                         new_settings.modulo = 8;
 309                         new_settings.window = 7;
 310                         new_settings.t1 = 3;
 311                         new_settings.t2 = 1;
 312                         new_settings.n2 = 10;
 313                 } else {
 314                         if (copy_from_user(&new_settings, x25_s, size))
 315                                 return -EFAULT;
 316
 317                         if ((new_settings.dce != 0 &&
 318                              new_settings.dce != 1) ||
 319                             (new_settings.modulo != 8 &&
 320                              new_settings.modulo != 128) ||
 321                             new_settings.window < 1 ||
 322                             (new_settings.modulo == 8 &&
 323                              new_settings.window > 7) ||
 324                             (new_settings.modulo == 128 &&
 325                              new_settings.window > 127) ||
 326                             new_settings.t1 < 1 ||
 327                             new_settings.t1 > 255 ||
 328                             new_settings.t2 < 1 ||
 329                             new_settings.t2 > 255 ||
 330                             new_settings.n2 < 1 ||
 331                             new_settings.n2 > 255)
 332                                 return -EINVAL;
 333                 }
 334
 335                 result = hdlc->attach(dev, ENCODING_NRZ,
 336                                       PARITY_CRC16_PR1_CCITT);
 337                 if (result)
 338                         return result;
 339
 340                 result = attach_hdlc_protocol(dev, &proto,
 341                                               sizeof(struct x25_state));
 342                 if (result)
 343                         return result;
 344
 345                 memcpy(&state(hdlc)->settings, &new_settings, size);
 346                 state(hdlc)->up = false;
 347                 spin_lock_init(&state(hdlc)->up_lock);
 348                 skb_queue_head_init(&state(hdlc)->rx_queue);
 349                 tasklet_setup(&state(hdlc)->rx_tasklet, x25_rx_queue_kick);
 350
 351                 /* There's no header_ops so hard_header_len should be 0. */
 352                 dev->hard_header_len = 0;
 353                 /* When transmitting data:
 354                  * first we'll remove a pseudo header of 1 byte,
 355                  * then we'll prepend an LAPB header of at most 3 bytes.
 356                  */
 357                 dev->needed_headroom = 3 - 1;
 358
 359                 dev->type = ARPHRD_X25;
 360                 call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
 361                 netif_dormant_off(dev);
 362                 return 0;
 363         }
 364
 365         return -EINVAL;
 366 }
 367
 368 static int __init hdlc_x25_init(void)
 369 {
 370         register_hdlc_protocol(&proto);
 371         return 0;
 372 }
 373
 374 static void __exit hdlc_x25_exit(void)
 375 {
 376         unregister_hdlc_protocol(&proto);
 377 }
 378
 379 module_init(hdlc_x25_init);
 380 module_exit(hdlc_x25_exit);
 381
 382 MODULE_AUTHOR("Krzysztof Halasa <khc@pm.waw.pl>");
 383 MODULE_DESCRIPTION("X.25 protocol support for generic HDLC");
 384 MODULE_LICENSE("GPL v2");