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 #define pr_fmt(fmt) "X25: " fmt
  25
  26 #include <linux/kernel.h>
  27 #include <linux/jiffies.h>
  28 #include <linux/timer.h>
  29 #include <linux/slab.h>
  30 #include <linux/netdevice.h>
  31 #include <linux/skbuff.h>
  32 #include <linux/uaccess.h>
  33 #include <linux/init.h>
  34 #include <net/x25.h>
  35
  36 LIST_HEAD(x25_neigh_list);
  37 DEFINE_RWLOCK(x25_neigh_list_lock);
  38
  39 static void x25_t20timer_expiry(struct timer_list *);
  40
  41 static void x25_transmit_restart_confirmation(struct x25_neigh *nb);
  42 static void x25_transmit_restart_request(struct x25_neigh *nb);
  43
  44 /*
  45  *      Linux set/reset timer routines
  46  */
  47 static inline void x25_start_t20timer(struct x25_neigh *nb)
  48 {
  49         mod_timer(&nb->t20timer, jiffies + nb->t20);
  50 }
  51
  52 static void x25_t20timer_expiry(struct timer_list *t)
  53 {
  54         struct x25_neigh *nb = from_timer(nb, t, t20timer);
  55
  56         x25_transmit_restart_request(nb);
  57
  58         x25_start_t20timer(nb);
  59 }
  60
  61 static inline void x25_stop_t20timer(struct x25_neigh *nb)
  62 {
  63         del_timer(&nb->t20timer);
  64 }
  65
  66 static inline int x25_t20timer_pending(struct x25_neigh *nb)
  67 {
  68         return timer_pending(&nb->t20timer);
  69 }
  70
  71 /*
  72  *      This handles all restart and diagnostic frames.
  73  */
  74 void x25_link_control(struct sk_buff *skb, struct x25_neigh *nb,
  75                       unsigned short frametype)
  76 {
  77         struct sk_buff *skbn;
  78         int confirm;
  79
  80         switch (frametype) {
  81         case X25_RESTART_REQUEST:
  82                 confirm = !x25_t20timer_pending(nb);
  83                 x25_stop_t20timer(nb);
  84                 nb->state = X25_LINK_STATE_3;
  85                 if (confirm)
  86                         x25_transmit_restart_confirmation(nb);
  87                 break;
  88
  89         case X25_RESTART_CONFIRMATION:
  90                 x25_stop_t20timer(nb);
  91                 nb->state = X25_LINK_STATE_3;
  92                 break;
  93
  94         case X25_DIAGNOSTIC:
  95                 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 4))
  96                         break;
  97
  98                 pr_warn("diagnostic #%d - %02X %02X %02X\n",
  99                        skb->data[3], skb->data[4],
 100                        skb->data[5], skb->data[6]);
 101                 break;
 102
 103         default:
 104                 pr_warn("received unknown %02X with LCI 000\n",
 105                        frametype);
 106                 break;
 107         }
 108
 109         if (nb->state == X25_LINK_STATE_3)
 110                 while ((skbn = skb_dequeue(&nb->queue)) != NULL)
 111                         x25_send_frame(skbn, nb);
 112 }
 113
 114 /*
 115  *      This routine is called when a Restart Request is needed
 116  */
 117 static void x25_transmit_restart_request(struct x25_neigh *nb)
 118 {
 119         unsigned char *dptr;
 120         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
 121         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 122
 123         if (!skb)
 124                 return;
 125
 126         skb_reserve(skb, X25_MAX_L2_LEN);
 127
 128         dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
 129
 130         *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
 131         *dptr++ = 0x00;
 132         *dptr++ = X25_RESTART_REQUEST;
 133         *dptr++ = 0x00;
 134         *dptr++ = 0;
 135
 136         skb->sk = NULL;
 137
 138         x25_send_frame(skb, nb);
 139 }
 140
 141 /*
 142  * This routine is called when a Restart Confirmation is needed
 143  */
 144 static void x25_transmit_restart_confirmation(struct x25_neigh *nb)
 145 {
 146         unsigned char *dptr;
 147         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN;
 148         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 149
 150         if (!skb)
 151                 return;
 152
 153         skb_reserve(skb, X25_MAX_L2_LEN);
 154
 155         dptr = skb_put(skb, X25_STD_MIN_LEN);
 156
 157         *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
 158         *dptr++ = 0x00;
 159         *dptr++ = X25_RESTART_CONFIRMATION;
 160
 161         skb->sk = NULL;
 162
 163         x25_send_frame(skb, nb);
 164 }
 165
 166 /*
 167  *      This routine is called when a Clear Request is needed outside of the context
 168  *      of a connected socket.
 169  */
 170 void x25_transmit_clear_request(struct x25_neigh *nb, unsigned int lci,
 171                                 unsigned char cause)
 172 {
 173         unsigned char *dptr;
 174         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
 175         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 176
 177         if (!skb)
 178                 return;
 179
 180         skb_reserve(skb, X25_MAX_L2_LEN);
 181
 182         dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
 183
 184         *dptr++ = ((lci >> 8) & 0x0F) | (nb->extended ?
 185                                          X25_GFI_EXTSEQ :
 186                                          X25_GFI_STDSEQ);
 187         *dptr++ = (lci >> 0) & 0xFF;
 188         *dptr++ = X25_CLEAR_REQUEST;
 189         *dptr++ = cause;
 190         *dptr++ = 0x00;
 191
 192         skb->sk = NULL;
 193
 194         x25_send_frame(skb, nb);
 195 }
 196
 197 void x25_transmit_link(struct sk_buff *skb, struct x25_neigh *nb)
 198 {
 199         switch (nb->state) {
 200         case X25_LINK_STATE_0:
 201                 skb_queue_tail(&nb->queue, skb);
 202                 nb->state = X25_LINK_STATE_1;
 203                 x25_establish_link(nb);
 204                 break;
 205         case X25_LINK_STATE_1:
 206         case X25_LINK_STATE_2:
 207                 skb_queue_tail(&nb->queue, skb);
 208                 break;
 209         case X25_LINK_STATE_3:
 210                 x25_send_frame(skb, nb);
 211                 break;
 212         }
 213 }
 214
 215 /*
 216  *      Called when the link layer has become established.
 217  */
 218 void x25_link_established(struct x25_neigh *nb)
 219 {
 220         switch (nb->state) {
 221         case X25_LINK_STATE_0:
 222                 nb->state = X25_LINK_STATE_2;
 223                 break;
 224         case X25_LINK_STATE_1:
 225                 x25_transmit_restart_request(nb);
 226                 nb->state = X25_LINK_STATE_2;
 227                 x25_start_t20timer(nb);
 228                 break;
 229         }
 230 }
 231
 232 /*
 233  *      Called when the link layer has terminated, or an establishment
 234  *      request has failed.
 235  */
 236
 237 void x25_link_terminated(struct x25_neigh *nb)
 238 {
 239         nb->state = X25_LINK_STATE_0;
 240         /* Out of order: clear existing virtual calls (X.25 03/93 4.6.3) */
 241         x25_kill_by_neigh(nb);
 242 }
 243
 244 /*
 245  *      Add a new device.
 246  */
 247 void x25_link_device_up(struct net_device *dev)
 248 {
 249         struct x25_neigh *nb = kmalloc(sizeof(*nb), GFP_ATOMIC);
 250
 251         if (!nb)
 252                 return;
 253
 254         skb_queue_head_init(&nb->queue);
 255         timer_setup(&nb->t20timer, x25_t20timer_expiry, 0);
 256
 257         dev_hold(dev);
 258         nb->dev      = dev;
 259         nb->state    = X25_LINK_STATE_0;
 260         nb->extended = 0;
 261         /*
 262          * Enables negotiation
 263          */
 264         nb->global_facil_mask = X25_MASK_REVERSE |
 265                                        X25_MASK_THROUGHPUT |
 266                                        X25_MASK_PACKET_SIZE |
 267                                        X25_MASK_WINDOW_SIZE;
 268         nb->t20      = sysctl_x25_restart_request_timeout;
 269         refcount_set(&nb->refcnt, 1);
 270
 271         write_lock_bh(&x25_neigh_list_lock);
 272         list_add(&nb->node, &x25_neigh_list);
 273         write_unlock_bh(&x25_neigh_list_lock);
 274 }
 275
 276 /**
 277  *      __x25_remove_neigh - remove neighbour from x25_neigh_list
 278  *      @nb - neigh to remove
 279  *
 280  *      Remove neighbour from x25_neigh_list. If it was there.
 281  *      Caller must hold x25_neigh_list_lock.
 282  */
 283 static void __x25_remove_neigh(struct x25_neigh *nb)
 284 {
 285         skb_queue_purge(&nb->queue);
 286         x25_stop_t20timer(nb);
 287
 288         if (nb->node.next) {
 289                 list_del(&nb->node);
 290                 x25_neigh_put(nb);
 291         }
 292 }
 293
 294 /*
 295  *      A device has been removed, remove its links.
 296  */
 297 void x25_link_device_down(struct net_device *dev)
 298 {
 299         struct x25_neigh *nb;
 300         struct list_head *entry, *tmp;
 301
 302         write_lock_bh(&x25_neigh_list_lock);
 303
 304         list_for_each_safe(entry, tmp, &x25_neigh_list) {
 305                 nb = list_entry(entry, struct x25_neigh, node);
 306
 307                 if (nb->dev == dev) {
 308                         __x25_remove_neigh(nb);
 309                         dev_put(dev);
 310                 }
 311         }
 312
 313         write_unlock_bh(&x25_neigh_list_lock);
 314 }
 315
 316 /*
 317  *      Given a device, return the neighbour address.
 318  */
 319 struct x25_neigh *x25_get_neigh(struct net_device *dev)
 320 {
 321         struct x25_neigh *nb, *use = NULL;
 322         struct list_head *entry;
 323
 324         read_lock_bh(&x25_neigh_list_lock);
 325         list_for_each(entry, &x25_neigh_list) {
 326                 nb = list_entry(entry, struct x25_neigh, node);
 327
 328                 if (nb->dev == dev) {
 329                         use = nb;
 330                         break;
 331                 }
 332         }
 333
 334         if (use)
 335                 x25_neigh_hold(use);
 336         read_unlock_bh(&x25_neigh_list_lock);
 337         return use;
 338 }
 339
 340 /*
 341  *      Handle the ioctls that control the subscription functions.
 342  */
 343 int x25_subscr_ioctl(unsigned int cmd, void __user *arg)
 344 {
 345         struct x25_subscrip_struct x25_subscr;
 346         struct x25_neigh *nb;
 347         struct net_device *dev;
 348         int rc = -EINVAL;
 349
 350         if (cmd != SIOCX25GSUBSCRIP && cmd != SIOCX25SSUBSCRIP)
 351                 goto out;
 352
 353         rc = -EFAULT;
 354         if (copy_from_user(&x25_subscr, arg, sizeof(x25_subscr)))
 355                 goto out;
 356
 357         rc = -EINVAL;
 358         if ((dev = x25_dev_get(x25_subscr.device)) == NULL)
 359                 goto out;
 360
 361         if ((nb = x25_get_neigh(dev)) == NULL)
 362                 goto out_dev_put;
 363
 364         dev_put(dev);
 365
 366         if (cmd == SIOCX25GSUBSCRIP) {
 367                 read_lock_bh(&x25_neigh_list_lock);
 368                 x25_subscr.extended          = nb->extended;
 369                 x25_subscr.global_facil_mask = nb->global_facil_mask;
 370                 read_unlock_bh(&x25_neigh_list_lock);
 371                 rc = copy_to_user(arg, &x25_subscr,
 372                                   sizeof(x25_subscr)) ? -EFAULT : 0;
 373         } else {
 374                 rc = -EINVAL;
 375                 if (!(x25_subscr.extended && x25_subscr.extended != 1)) {
 376                         rc = 0;
 377                         write_lock_bh(&x25_neigh_list_lock);
 378                         nb->extended         = x25_subscr.extended;
 379                         nb->global_facil_mask = x25_subscr.global_facil_mask;
 380                         write_unlock_bh(&x25_neigh_list_lock);
 381                 }
 382         }
 383         x25_neigh_put(nb);
 384 out:
 385         return rc;
 386 out_dev_put:
 387         dev_put(dev);
 388         goto out;
 389 }
 390
 391
 392 /*
 393  *      Release all memory associated with X.25 neighbour structures.
 394  */
 395 void __exit x25_link_free(void)
 396 {
 397         struct x25_neigh *nb;
 398         struct list_head *entry, *tmp;
 399
 400         write_lock_bh(&x25_neigh_list_lock);
 401
 402         list_for_each_safe(entry, tmp, &x25_neigh_list) {
 403                 struct net_device *dev;
 404
 405                 nb = list_entry(entry, struct x25_neigh, node);
 406                 dev = nb->dev;
 407                 __x25_remove_neigh(nb);
 408                 dev_put(dev);
 409         }
 410         write_unlock_bh(&x25_neigh_list_lock);
 411 }