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 LIST_HEAD(x25_neigh_list);
  35 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                 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 4))
  94                         break;
  95
  96                 printk(KERN_WARNING "x25: diagnostic #%d - %02X %02X %02X\n",
  97                        skb->data[3], skb->data[4],
  98                        skb->data[5], skb->data[6]);
  99                 break;
 100
 101         default:
 102                 printk(KERN_WARNING "x25: received unknown %02X with LCI 000\n",
 103                        frametype);
 104                 break;
 105         }
 106
 107         if (nb->state == X25_LINK_STATE_3)
 108                 while ((skbn = skb_dequeue(&nb->queue)) != NULL)
 109                         x25_send_frame(skbn, nb);
 110 }
 111
 112 /*
 113  *      This routine is called when a Restart Request is needed
 114  */
 115 static void x25_transmit_restart_request(struct x25_neigh *nb)
 116 {
 117         unsigned char *dptr;
 118         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
 119         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 120
 121         if (!skb)
 122                 return;
 123
 124         skb_reserve(skb, X25_MAX_L2_LEN);
 125
 126         dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
 127
 128         *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
 129         *dptr++ = 0x00;
 130         *dptr++ = X25_RESTART_REQUEST;
 131         *dptr++ = 0x00;
 132         *dptr++ = 0;
 133
 134         skb->sk = NULL;
 135
 136         x25_send_frame(skb, nb);
 137 }
 138
 139 /*
 140  * This routine is called when a Restart Confirmation is needed
 141  */
 142 static void x25_transmit_restart_confirmation(struct x25_neigh *nb)
 143 {
 144         unsigned char *dptr;
 145         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN;
 146         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 147
 148         if (!skb)
 149                 return;
 150
 151         skb_reserve(skb, X25_MAX_L2_LEN);
 152
 153         dptr = skb_put(skb, X25_STD_MIN_LEN);
 154
 155         *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
 156         *dptr++ = 0x00;
 157         *dptr++ = X25_RESTART_CONFIRMATION;
 158
 159         skb->sk = NULL;
 160
 161         x25_send_frame(skb, nb);
 162 }
 163
 164 /*
 165  *      This routine is called when a Clear Request is needed outside of the context
 166  *      of a connected socket.
 167  */
 168 void x25_transmit_clear_request(struct x25_neigh *nb, unsigned int lci,
 169                                 unsigned char cause)
 170 {
 171         unsigned char *dptr;
 172         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
 173         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 174
 175         if (!skb)
 176                 return;
 177
 178         skb_reserve(skb, X25_MAX_L2_LEN);
 179
 180         dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
 181
 182         *dptr++ = ((lci >> 8) & 0x0F) | (nb->extended ?
 183                                          X25_GFI_EXTSEQ :
 184                                          X25_GFI_STDSEQ);
 185         *dptr++ = (lci >> 0) & 0xFF;
 186         *dptr++ = X25_CLEAR_REQUEST;
 187         *dptr++ = cause;
 188         *dptr++ = 0x00;
 189
 190         skb->sk = NULL;
 191
 192         x25_send_frame(skb, nb);
 193 }
 194
 195 void x25_transmit_link(struct sk_buff *skb, struct x25_neigh *nb)
 196 {
 197         switch (nb->state) {
 198         case X25_LINK_STATE_0:
 199                 skb_queue_tail(&nb->queue, skb);
 200                 nb->state = X25_LINK_STATE_1;
 201                 x25_establish_link(nb);
 202                 break;
 203         case X25_LINK_STATE_1:
 204         case X25_LINK_STATE_2:
 205                 skb_queue_tail(&nb->queue, skb);
 206                 break;
 207         case X25_LINK_STATE_3:
 208                 x25_send_frame(skb, nb);
 209                 break;
 210         }
 211 }
 212
 213 /*
 214  *      Called when the link layer has become established.
 215  */
 216 void x25_link_established(struct x25_neigh *nb)
 217 {
 218         switch (nb->state) {
 219         case X25_LINK_STATE_0:
 220                 nb->state = X25_LINK_STATE_2;
 221                 break;
 222         case X25_LINK_STATE_1:
 223                 x25_transmit_restart_request(nb);
 224                 nb->state = X25_LINK_STATE_2;
 225                 x25_start_t20timer(nb);
 226                 break;
 227         }
 228 }
 229
 230 /*
 231  *      Called when the link layer has terminated, or an establishment
 232  *      request has failed.
 233  */
 234
 235 void x25_link_terminated(struct x25_neigh *nb)
 236 {
 237         nb->state = X25_LINK_STATE_0;
 238         /* Out of order: clear existing virtual calls (X.25 03/93 4.6.3) */
 239         x25_kill_by_neigh(nb);
 240 }
 241
 242 /*
 243  *      Add a new device.
 244  */
 245 void x25_link_device_up(struct net_device *dev)
 246 {
 247         struct x25_neigh *nb = kmalloc(sizeof(*nb), GFP_ATOMIC);
 248
 249         if (!nb)
 250                 return;
 251
 252         skb_queue_head_init(&nb->queue);
 253         setup_timer(&nb->t20timer, x25_t20timer_expiry, (unsigned long)nb);
 254
 255         dev_hold(dev);
 256         nb->dev      = dev;
 257         nb->state    = X25_LINK_STATE_0;
 258         nb->extended = 0;
 259         /*
 260          * Enables negotiation
 261          */
 262         nb->global_facil_mask = X25_MASK_REVERSE |
 263                                        X25_MASK_THROUGHPUT |
 264                                        X25_MASK_PACKET_SIZE |
 265                                        X25_MASK_WINDOW_SIZE;
 266         nb->t20      = sysctl_x25_restart_request_timeout;
 267         atomic_set(&nb->refcnt, 1);
 268
 269         write_lock_bh(&x25_neigh_list_lock);
 270         list_add(&nb->node, &x25_neigh_list);
 271         write_unlock_bh(&x25_neigh_list_lock);
 272 }
 273
 274 /**
 275  *      __x25_remove_neigh - remove neighbour from x25_neigh_list
 276  *      @nb - neigh to remove
 277  *
 278  *      Remove neighbour from x25_neigh_list. If it was there.
 279  *      Caller must hold x25_neigh_list_lock.
 280  */
 281 static void __x25_remove_neigh(struct x25_neigh *nb)
 282 {
 283         skb_queue_purge(&nb->queue);
 284         x25_stop_t20timer(nb);
 285
 286         if (nb->node.next) {
 287                 list_del(&nb->node);
 288                 x25_neigh_put(nb);
 289         }
 290 }
 291
 292 /*
 293  *      A device has been removed, remove its links.
 294  */
 295 void x25_link_device_down(struct net_device *dev)
 296 {
 297         struct x25_neigh *nb;
 298         struct list_head *entry, *tmp;
 299
 300         write_lock_bh(&x25_neigh_list_lock);
 301
 302         list_for_each_safe(entry, tmp, &x25_neigh_list) {
 303                 nb = list_entry(entry, struct x25_neigh, node);
 304
 305                 if (nb->dev == dev) {
 306                         __x25_remove_neigh(nb);
 307                         dev_put(dev);
 308                 }
 309         }
 310
 311         write_unlock_bh(&x25_neigh_list_lock);
 312 }
 313
 314 /*
 315  *      Given a device, return the neighbour address.
 316  */
 317 struct x25_neigh *x25_get_neigh(struct net_device *dev)
 318 {
 319         struct x25_neigh *nb, *use = NULL;
 320         struct list_head *entry;
 321
 322         read_lock_bh(&x25_neigh_list_lock);
 323         list_for_each(entry, &x25_neigh_list) {
 324                 nb = list_entry(entry, struct x25_neigh, node);
 325
 326                 if (nb->dev == dev) {
 327                         use = nb;
 328                         break;
 329                 }
 330         }
 331
 332         if (use)
 333                 x25_neigh_hold(use);
 334         read_unlock_bh(&x25_neigh_list_lock);
 335         return use;
 336 }
 337
 338 /*
 339  *      Handle the ioctls that control the subscription functions.
 340  */
 341 int x25_subscr_ioctl(unsigned int cmd, void __user *arg)
 342 {
 343         struct x25_subscrip_struct x25_subscr;
 344         struct x25_neigh *nb;
 345         struct net_device *dev;
 346         int rc = -EINVAL;
 347
 348         if (cmd != SIOCX25GSUBSCRIP && cmd != SIOCX25SSUBSCRIP)
 349                 goto out;
 350
 351         rc = -EFAULT;
 352         if (copy_from_user(&x25_subscr, arg, sizeof(x25_subscr)))
 353                 goto out;
 354
 355         rc = -EINVAL;
 356         if ((dev = x25_dev_get(x25_subscr.device)) == NULL)
 357                 goto out;
 358
 359         if ((nb = x25_get_neigh(dev)) == NULL)
 360                 goto out_dev_put;
 361
 362         dev_put(dev);
 363
 364         if (cmd == SIOCX25GSUBSCRIP) {
 365                 read_lock_bh(&x25_neigh_list_lock);
 366                 x25_subscr.extended          = nb->extended;
 367                 x25_subscr.global_facil_mask = nb->global_facil_mask;
 368                 read_unlock_bh(&x25_neigh_list_lock);
 369                 rc = copy_to_user(arg, &x25_subscr,
 370                                   sizeof(x25_subscr)) ? -EFAULT : 0;
 371         } else {
 372                 rc = -EINVAL;
 373                 if (!(x25_subscr.extended && x25_subscr.extended != 1)) {
 374                         rc = 0;
 375                         write_lock_bh(&x25_neigh_list_lock);
 376                         nb->extended         = x25_subscr.extended;
 377                         nb->global_facil_mask = x25_subscr.global_facil_mask;
 378                         write_unlock_bh(&x25_neigh_list_lock);
 379                 }
 380         }
 381         x25_neigh_put(nb);
 382 out:
 383         return rc;
 384 out_dev_put:
 385         dev_put(dev);
 386         goto out;
 387 }
 388
 389
 390 /*
 391  *      Release all memory associated with X.25 neighbour structures.
 392  */
 393 void __exit x25_link_free(void)
 394 {
 395         struct x25_neigh *nb;
 396         struct list_head *entry, *tmp;
 397
 398         write_lock_bh(&x25_neigh_list_lock);
 399
 400         list_for_each_safe(entry, tmp, &x25_neigh_list) {
 401                 struct net_device *dev;
 402
 403                 nb = list_entry(entry, struct x25_neigh, node);
 404                 dev = nb->dev;
 405                 __x25_remove_neigh(nb);
 406                 dev_put(dev);
 407         }
 408         write_unlock_bh(&x25_neigh_list_lock);
 409 }