net/x25/x25_link.c

   1 /*
   2  *      X.25 Packet Layer release 002
   3  *
   4  *      This is ALPHA test software. This code may break your machine,
   5  *      randomly fail to work with new releases, misbehave and/or generally
   6  *      screw up. It might even work.
   7  *
   8  *      This code REQUIRES 2.1.15 or higher
   9  *
  10  *      This module:
  11  *              This module is free software; you can redistribute it and/or
  12  *              modify it under the terms of the GNU General Public License
  13  *              as published by the Free Software Foundation; either version
  14  *              2 of the License, or (at your option) any later version.
  15  *
  16  *      History
  17  *      X.25 001        Jonathan Naylor   Started coding.
  18  *      X.25 002        Jonathan Naylor   New timer architecture.
  19  *      mar/20/00       Daniela Squassoni Disabling/enabling of facilities
  20  *                                        negotiation.
  21  *      2000-09-04      Henner Eisen      dev_hold() / dev_put() for x25_neigh.
  22  */
  23
  24 #include <linux/kernel.h>
  25 #include <linux/jiffies.h>
  26 #include <linux/timer.h>
  27 #include <linux/slab.h>
  28 #include <linux/netdevice.h>
  29 #include <linux/skbuff.h>
  30 #include <asm/uaccess.h>
  31 #include <linux/init.h>
  32 #include <net/x25.h>
  33
  34 static LIST_HEAD(x25_neigh_list);
  35 static DEFINE_RWLOCK(x25_neigh_list_lock);
  36
  37 static void x25_t20timer_expiry(unsigned long);
  38
  39 static void x25_transmit_restart_confirmation(struct x25_neigh *nb);
  40 static void x25_transmit_restart_request(struct x25_neigh *nb);
  41
  42 /*
  43  *      Linux set/reset timer routines
  44  */
  45 static inline void x25_start_t20timer(struct x25_neigh *nb)
  46 {
  47         mod_timer(&nb->t20timer, jiffies + nb->t20);
  48 }
  49
  50 static void x25_t20timer_expiry(unsigned long param)
  51 {
  52         struct x25_neigh *nb = (struct x25_neigh *)param;
  53
  54         x25_transmit_restart_request(nb);
  55
  56         x25_start_t20timer(nb);
  57 }
  58
  59 static inline void x25_stop_t20timer(struct x25_neigh *nb)
  60 {
  61         del_timer(&nb->t20timer);
  62 }
  63
  64 static inline int x25_t20timer_pending(struct x25_neigh *nb)
  65 {
  66         return timer_pending(&nb->t20timer);
  67 }
  68
  69 /*
  70  *      This handles all restart and diagnostic frames.
  71  */
  72 void x25_link_control(struct sk_buff *skb, struct x25_neigh *nb,
  73                       unsigned short frametype)
  74 {
  75         struct sk_buff *skbn;
  76         int confirm;
  77
  78         switch (frametype) {
  79                 case X25_RESTART_REQUEST:
  80                         confirm = !x25_t20timer_pending(nb);
  81                         x25_stop_t20timer(nb);
  82                         nb->state = X25_LINK_STATE_3;
  83                         if (confirm)
  84                                 x25_transmit_restart_confirmation(nb);
  85                         break;
  86
  87                 case X25_RESTART_CONFIRMATION:
  88                         x25_stop_t20timer(nb);
  89                         nb->state = X25_LINK_STATE_3;
  90                         break;
  91
  92                 case X25_DIAGNOSTIC:
  93                         printk(KERN_WARNING "x25: diagnostic #%d - "
  94                                "%02X %02X %02X\n",
  95                                skb->data[3], skb->data[4],
  96                                skb->data[5], skb->data[6]);
  97                         break;
  98
  99                 default:
 100                         printk(KERN_WARNING "x25: received unknown %02X "
 101                                "with LCI 000\n", frametype);
 102                         break;
 103         }
 104
 105         if (nb->state == X25_LINK_STATE_3)
 106                 while ((skbn = skb_dequeue(&nb->queue)) != NULL)
 107                         x25_send_frame(skbn, nb);
 108 }
 109
 110 /*
 111  *      This routine is called when a Restart Request is needed
 112  */
 113 static void x25_transmit_restart_request(struct x25_neigh *nb)
 114 {
 115         unsigned char *dptr;
 116         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
 117         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 118
 119         if (!skb)
 120                 return;
 121
 122         skb_reserve(skb, X25_MAX_L2_LEN);
 123
 124         dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
 125
 126         *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
 127         *dptr++ = 0x00;
 128         *dptr++ = X25_RESTART_REQUEST;
 129         *dptr++ = 0x00;
 130         *dptr++ = 0;
 131
 132         skb->sk = NULL;
 133
 134         x25_send_frame(skb, nb);
 135 }
 136
 137 /*
 138  * This routine is called when a Restart Confirmation is needed
 139  */
 140 static void x25_transmit_restart_confirmation(struct x25_neigh *nb)
 141 {
 142         unsigned char *dptr;
 143         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN;
 144         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 145
 146         if (!skb)
 147                 return;
 148
 149         skb_reserve(skb, X25_MAX_L2_LEN);
 150
 151         dptr = skb_put(skb, X25_STD_MIN_LEN);
 152
 153         *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
 154         *dptr++ = 0x00;
 155         *dptr++ = X25_RESTART_CONFIRMATION;
 156
 157         skb->sk = NULL;
 158
 159         x25_send_frame(skb, nb);
 160 }
 161
 162 /*
 163  *      This routine is called when a Clear Request is needed outside of the context
 164  *      of a connected socket.
 165  */
 166 void x25_transmit_clear_request(struct x25_neigh *nb, unsigned int lci,
 167                                 unsigned char cause)
 168 {
 169         unsigned char *dptr;
 170         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
 171         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 172
 173         if (!skb)
 174                 return;
 175
 176         skb_reserve(skb, X25_MAX_L2_LEN);
 177
 178         dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
 179
 180         *dptr++ = ((lci >> 8) & 0x0F) | (nb->extended ?
 181                                          X25_GFI_EXTSEQ :
 182                                          X25_GFI_STDSEQ);
 183         *dptr++ = (lci >> 0) & 0xFF;
 184         *dptr++ = X25_CLEAR_REQUEST;
 185         *dptr++ = cause;
 186         *dptr++ = 0x00;
 187
 188         skb->sk = NULL;
 189
 190         x25_send_frame(skb, nb);
 191 }
 192
 193 void x25_transmit_link(struct sk_buff *skb, struct x25_neigh *nb)
 194 {
 195         switch (nb->state) {
 196                 case X25_LINK_STATE_0:
 197                         skb_queue_tail(&nb->queue, skb);
 198                         nb->state = X25_LINK_STATE_1;
 199                         x25_establish_link(nb);
 200                         break;
 201                 case X25_LINK_STATE_1:
 202                 case X25_LINK_STATE_2:
 203                         skb_queue_tail(&nb->queue, skb);
 204                         break;
 205                 case X25_LINK_STATE_3:
 206                         x25_send_frame(skb, nb);
 207                         break;
 208         }
 209 }
 210
 211 /*
 212  *      Called when the link layer has become established.
 213  */
 214 void x25_link_established(struct x25_neigh *nb)
 215 {
 216         switch (nb->state) {
 217                 case X25_LINK_STATE_0:
 218                         nb->state = X25_LINK_STATE_2;
 219                         break;
 220                 case X25_LINK_STATE_1:
 221                         x25_transmit_restart_request(nb);
 222                         nb->state = X25_LINK_STATE_2;
 223                         x25_start_t20timer(nb);
 224                         break;
 225         }
 226 }
 227
 228 /*
 229  *      Called when the link layer has terminated, or an establishment
 230  *      request has failed.
 231  */
 232
 233 void x25_link_terminated(struct x25_neigh *nb)
 234 {
 235         nb->state = X25_LINK_STATE_0;
 236         /* Out of order: clear existing virtual calls (X.25 03/93 4.6.3) */
 237         x25_kill_by_neigh(nb);
 238 }
 239
 240 /*
 241  *      Add a new device.
 242  */
 243 void x25_link_device_up(struct net_device *dev)
 244 {
 245         struct x25_neigh *nb = kmalloc(sizeof(*nb), GFP_ATOMIC);
 246
 247         if (!nb)
 248                 return;
 249
 250         skb_queue_head_init(&nb->queue);
 251         setup_timer(&nb->t20timer, x25_t20timer_expiry, (unsigned long)nb);
 252
 253         dev_hold(dev);
 254         nb->dev      = dev;
 255         nb->state    = X25_LINK_STATE_0;
 256         nb->extended = 0;
 257         /*
 258          * Enables negotiation
 259          */
 260         nb->global_facil_mask = X25_MASK_REVERSE |
 261                                        X25_MASK_THROUGHPUT |
 262                                        X25_MASK_PACKET_SIZE |
 263                                        X25_MASK_WINDOW_SIZE;
 264         nb->t20      = sysctl_x25_restart_request_timeout;
 265         atomic_set(&nb->refcnt, 1);
 266
 267         write_lock_bh(&x25_neigh_list_lock);
 268         list_add(&nb->node, &x25_neigh_list);
 269         write_unlock_bh(&x25_neigh_list_lock);
 270 }
 271
 272 /**
 273  *      __x25_remove_neigh - remove neighbour from x25_neigh_list
 274  *      @nb - neigh to remove
 275  *
 276  *      Remove neighbour from x25_neigh_list. If it was there.
 277  *      Caller must hold x25_neigh_list_lock.
 278  */
 279 static void __x25_remove_neigh(struct x25_neigh *nb)
 280 {
 281         skb_queue_purge(&nb->queue);
 282         x25_stop_t20timer(nb);
 283
 284         if (nb->node.next) {
 285                 list_del(&nb->node);
 286                 x25_neigh_put(nb);
 287         }
 288 }
 289
 290 /*
 291  *      A device has been removed, remove its links.
 292  */
 293 void x25_link_device_down(struct net_device *dev)
 294 {
 295         struct x25_neigh *nb;
 296         struct list_head *entry, *tmp;
 297
 298         write_lock_bh(&x25_neigh_list_lock);
 299
 300         list_for_each_safe(entry, tmp, &x25_neigh_list) {
 301                 nb = list_entry(entry, struct x25_neigh, node);
 302
 303                 if (nb->dev == dev) {
 304                         __x25_remove_neigh(nb);
 305                         dev_put(dev);
 306                 }
 307         }
 308
 309         write_unlock_bh(&x25_neigh_list_lock);
 310 }
 311
 312 /*
 313  *      Given a device, return the neighbour address.
 314  */
 315 struct x25_neigh *x25_get_neigh(struct net_device *dev)
 316 {
 317         struct x25_neigh *nb, *use = NULL;
 318         struct list_head *entry;
 319
 320         read_lock_bh(&x25_neigh_list_lock);
 321         list_for_each(entry, &x25_neigh_list) {
 322                 nb = list_entry(entry, struct x25_neigh, node);
 323
 324                 if (nb->dev == dev) {
 325                         use = nb;
 326                         break;
 327                 }
 328         }
 329
 330         if (use)
 331                 x25_neigh_hold(use);
 332         read_unlock_bh(&x25_neigh_list_lock);
 333         return use;
 334 }
 335
 336 /*
 337  *      Handle the ioctls that control the subscription functions.
 338  */
 339 int x25_subscr_ioctl(unsigned int cmd, void __user *arg)
 340 {
 341         struct x25_subscrip_struct x25_subscr;
 342         struct x25_neigh *nb;
 343         struct net_device *dev;
 344         int rc = -EINVAL;
 345
 346         if (cmd != SIOCX25GSUBSCRIP && cmd != SIOCX25SSUBSCRIP)
 347                 goto out;
 348
 349         rc = -EFAULT;
 350         if (copy_from_user(&x25_subscr, arg, sizeof(x25_subscr)))
 351                 goto out;
 352
 353         rc = -EINVAL;
 354         if ((dev = x25_dev_get(x25_subscr.device)) == NULL)
 355                 goto out;
 356
 357         if ((nb = x25_get_neigh(dev)) == NULL)
 358                 goto out_dev_put;
 359
 360         dev_put(dev);
 361
 362         if (cmd == SIOCX25GSUBSCRIP) {
 363                 x25_subscr.extended          = nb->extended;
 364                 x25_subscr.global_facil_mask = nb->global_facil_mask;
 365                 rc = copy_to_user(arg, &x25_subscr,
 366                                   sizeof(x25_subscr)) ? -EFAULT : 0;
 367         } else {
 368                 rc = -EINVAL;
 369                 if (!(x25_subscr.extended && x25_subscr.extended != 1)) {
 370                         rc = 0;
 371                         nb->extended         = x25_subscr.extended;
 372                         nb->global_facil_mask = x25_subscr.global_facil_mask;
 373                 }
 374         }
 375         x25_neigh_put(nb);
 376 out:
 377         return rc;
 378 out_dev_put:
 379         dev_put(dev);
 380         goto out;
 381 }
 382
 383
 384 /*
 385  *      Release all memory associated with X.25 neighbour structures.
 386  */
 387 void __exit x25_link_free(void)
 388 {
 389         struct x25_neigh *nb;
 390         struct list_head *entry, *tmp;
 391
 392         write_lock_bh(&x25_neigh_list_lock);
 393
 394         list_for_each_safe(entry, tmp, &x25_neigh_list) {
 395                 nb = list_entry(entry, struct x25_neigh, node);
 396                 __x25_remove_neigh(nb);
 397         }
 398         write_unlock_bh(&x25_neigh_list_lock);
 399 }