net/x25/x25_link.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      X.25 Packet Layer release 002
   4  *
   5  *      This is ALPHA test software. This code may break your machine,
   6  *      randomly fail to work with new releases, misbehave and/or generally
   7  *      screw up. It might even work.
   8  *
   9  *      This code REQUIRES 2.1.15 or higher
  10  *
  11  *      History
  12  *      X.25 001        Jonathan Naylor   Started coding.
  13  *      X.25 002        Jonathan Naylor   New timer architecture.
  14  *      mar/20/00       Daniela Squassoni Disabling/enabling of facilities
  15  *                                        negotiation.
  16  *      2000-09-04      Henner Eisen      dev_hold() / dev_put() for x25_neigh.
  17  */
  18
  19 #define pr_fmt(fmt) "X25: " fmt
  20
  21 #include <linux/kernel.h>
  22 #include <linux/jiffies.h>
  23 #include <linux/timer.h>
  24 #include <linux/slab.h>
  25 #include <linux/netdevice.h>
  26 #include <linux/skbuff.h>
  27 #include <linux/uaccess.h>
  28 #include <linux/init.h>
  29 #include <net/x25.h>
  30
  31 LIST_HEAD(x25_neigh_list);
  32 DEFINE_RWLOCK(x25_neigh_list_lock);
  33
  34 static void x25_t20timer_expiry(struct timer_list *);
  35
  36 static void x25_transmit_restart_confirmation(struct x25_neigh *nb);
  37 static void x25_transmit_restart_request(struct x25_neigh *nb);
  38
  39 /*
  40  *      Linux set/reset timer routines
  41  */
  42 static inline void x25_start_t20timer(struct x25_neigh *nb)
  43 {
  44         mod_timer(&nb->t20timer, jiffies + nb->t20);
  45 }
  46
  47 static void x25_t20timer_expiry(struct timer_list *t)
  48 {
  49         struct x25_neigh *nb = from_timer(nb, t, t20timer);
  50
  51         x25_transmit_restart_request(nb);
  52
  53         x25_start_t20timer(nb);
  54 }
  55
  56 static inline void x25_stop_t20timer(struct x25_neigh *nb)
  57 {
  58         del_timer(&nb->t20timer);
  59 }
  60
  61 /*
  62  *      This handles all restart and diagnostic frames.
  63  */
  64 void x25_link_control(struct sk_buff *skb, struct x25_neigh *nb,
  65                       unsigned short frametype)
  66 {
  67         struct sk_buff *skbn;
  68
  69         switch (frametype) {
  70         case X25_RESTART_REQUEST:
  71                 switch (nb->state) {
  72                 case X25_LINK_STATE_0:
  73                         /* This can happen when the x25 module just gets loaded
  74                          * and doesn't know layer 2 has already connected
  75                          */
  76                         nb->state = X25_LINK_STATE_3;
  77                         x25_transmit_restart_confirmation(nb);
  78                         break;
  79                 case X25_LINK_STATE_2:
  80                         x25_stop_t20timer(nb);
  81                         nb->state = X25_LINK_STATE_3;
  82                         break;
  83                 case X25_LINK_STATE_3:
  84                         /* clear existing virtual calls */
  85                         x25_kill_by_neigh(nb);
  86
  87                         x25_transmit_restart_confirmation(nb);
  88                         break;
  89                 }
  90                 break;
  91
  92         case X25_RESTART_CONFIRMATION:
  93                 switch (nb->state) {
  94                 case X25_LINK_STATE_2:
  95                         x25_stop_t20timer(nb);
  96                         nb->state = X25_LINK_STATE_3;
  97                         break;
  98                 case X25_LINK_STATE_3:
  99                         /* clear existing virtual calls */
 100                         x25_kill_by_neigh(nb);
 101
 102                         x25_transmit_restart_request(nb);
 103                         nb->state = X25_LINK_STATE_2;
 104                         x25_start_t20timer(nb);
 105                         break;
 106                 }
 107                 break;
 108
 109         case X25_DIAGNOSTIC:
 110                 if (!pskb_may_pull(skb, X25_STD_MIN_LEN + 4))
 111                         break;
 112
 113                 pr_warn("diagnostic #%d - %02X %02X %02X\n",
 114                        skb->data[3], skb->data[4],
 115                        skb->data[5], skb->data[6]);
 116                 break;
 117
 118         default:
 119                 pr_warn("received unknown %02X with LCI 000\n",
 120                        frametype);
 121                 break;
 122         }
 123
 124         if (nb->state == X25_LINK_STATE_3)
 125                 while ((skbn = skb_dequeue(&nb->queue)) != NULL)
 126                         x25_send_frame(skbn, nb);
 127 }
 128
 129 /*
 130  *      This routine is called when a Restart Request is needed
 131  */
 132 static void x25_transmit_restart_request(struct x25_neigh *nb)
 133 {
 134         unsigned char *dptr;
 135         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
 136         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 137
 138         if (!skb)
 139                 return;
 140
 141         skb_reserve(skb, X25_MAX_L2_LEN);
 142
 143         dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
 144
 145         *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
 146         *dptr++ = 0x00;
 147         *dptr++ = X25_RESTART_REQUEST;
 148         *dptr++ = 0x00;
 149         *dptr++ = 0;
 150
 151         skb->sk = NULL;
 152
 153         x25_send_frame(skb, nb);
 154 }
 155
 156 /*
 157  * This routine is called when a Restart Confirmation is needed
 158  */
 159 static void x25_transmit_restart_confirmation(struct x25_neigh *nb)
 160 {
 161         unsigned char *dptr;
 162         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN;
 163         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 164
 165         if (!skb)
 166                 return;
 167
 168         skb_reserve(skb, X25_MAX_L2_LEN);
 169
 170         dptr = skb_put(skb, X25_STD_MIN_LEN);
 171
 172         *dptr++ = nb->extended ? X25_GFI_EXTSEQ : X25_GFI_STDSEQ;
 173         *dptr++ = 0x00;
 174         *dptr++ = X25_RESTART_CONFIRMATION;
 175
 176         skb->sk = NULL;
 177
 178         x25_send_frame(skb, nb);
 179 }
 180
 181 /*
 182  *      This routine is called when a Clear Request is needed outside of the context
 183  *      of a connected socket.
 184  */
 185 void x25_transmit_clear_request(struct x25_neigh *nb, unsigned int lci,
 186                                 unsigned char cause)
 187 {
 188         unsigned char *dptr;
 189         int len = X25_MAX_L2_LEN + X25_STD_MIN_LEN + 2;
 190         struct sk_buff *skb = alloc_skb(len, GFP_ATOMIC);
 191
 192         if (!skb)
 193                 return;
 194
 195         skb_reserve(skb, X25_MAX_L2_LEN);
 196
 197         dptr = skb_put(skb, X25_STD_MIN_LEN + 2);
 198
 199         *dptr++ = ((lci >> 8) & 0x0F) | (nb->extended ?
 200                                          X25_GFI_EXTSEQ :
 201                                          X25_GFI_STDSEQ);
 202         *dptr++ = (lci >> 0) & 0xFF;
 203         *dptr++ = X25_CLEAR_REQUEST;
 204         *dptr++ = cause;
 205         *dptr++ = 0x00;
 206
 207         skb->sk = NULL;
 208
 209         x25_send_frame(skb, nb);
 210 }
 211
 212 void x25_transmit_link(struct sk_buff *skb, struct x25_neigh *nb)
 213 {
 214         switch (nb->state) {
 215         case X25_LINK_STATE_0:
 216                 skb_queue_tail(&nb->queue, skb);
 217                 nb->state = X25_LINK_STATE_1;
 218                 x25_establish_link(nb);
 219                 break;
 220         case X25_LINK_STATE_1:
 221         case X25_LINK_STATE_2:
 222                 skb_queue_tail(&nb->queue, skb);
 223                 break;
 224         case X25_LINK_STATE_3:
 225                 x25_send_frame(skb, nb);
 226                 break;
 227         }
 228 }
 229
 230 /*
 231  *      Called when the link layer has become established.
 232  */
 233 void x25_link_established(struct x25_neigh *nb)
 234 {
 235         switch (nb->state) {
 236         case X25_LINK_STATE_0:
 237         case X25_LINK_STATE_1:
 238                 x25_transmit_restart_request(nb);
 239                 nb->state = X25_LINK_STATE_2;
 240                 x25_start_t20timer(nb);
 241                 break;
 242         }
 243 }
 244
 245 /*
 246  *      Called when the link layer has terminated, or an establishment
 247  *      request has failed.
 248  */
 249
 250 void x25_link_terminated(struct x25_neigh *nb)
 251 {
 252         nb->state = X25_LINK_STATE_0;
 253         skb_queue_purge(&nb->queue);
 254         x25_stop_t20timer(nb);
 255
 256         /* Out of order: clear existing virtual calls (X.25 03/93 4.6.3) */
 257         x25_kill_by_neigh(nb);
 258 }
 259
 260 /*
 261  *      Add a new device.
 262  */
 263 void x25_link_device_up(struct net_device *dev)
 264 {
 265         struct x25_neigh *nb = kmalloc(sizeof(*nb), GFP_ATOMIC);
 266
 267         if (!nb)
 268                 return;
 269
 270         skb_queue_head_init(&nb->queue);
 271         timer_setup(&nb->t20timer, x25_t20timer_expiry, 0);
 272
 273         dev_hold(dev);
 274         nb->dev      = dev;
 275         nb->state    = X25_LINK_STATE_0;
 276         nb->extended = 0;
 277         /*
 278          * Enables negotiation
 279          */
 280         nb->global_facil_mask = X25_MASK_REVERSE |
 281                                        X25_MASK_THROUGHPUT |
 282                                        X25_MASK_PACKET_SIZE |
 283                                        X25_MASK_WINDOW_SIZE;
 284         nb->t20      = sysctl_x25_restart_request_timeout;
 285         refcount_set(&nb->refcnt, 1);
 286
 287         write_lock_bh(&x25_neigh_list_lock);
 288         list_add(&nb->node, &x25_neigh_list);
 289         write_unlock_bh(&x25_neigh_list_lock);
 290 }
 291
 292 /**
 293  *      __x25_remove_neigh - remove neighbour from x25_neigh_list
 294  *      @nb: - neigh to remove
 295  *
 296  *      Remove neighbour from x25_neigh_list. If it was there.
 297  *      Caller must hold x25_neigh_list_lock.
 298  */
 299 static void __x25_remove_neigh(struct x25_neigh *nb)
 300 {
 301         if (nb->node.next) {
 302                 list_del(&nb->node);
 303                 x25_neigh_put(nb);
 304         }
 305 }
 306
 307 /*
 308  *      A device has been removed, remove its links.
 309  */
 310 void x25_link_device_down(struct net_device *dev)
 311 {
 312         struct x25_neigh *nb;
 313         struct list_head *entry, *tmp;
 314
 315         write_lock_bh(&x25_neigh_list_lock);
 316
 317         list_for_each_safe(entry, tmp, &x25_neigh_list) {
 318                 nb = list_entry(entry, struct x25_neigh, node);
 319
 320                 if (nb->dev == dev) {
 321                         __x25_remove_neigh(nb);
 322                         dev_put(dev);
 323                 }
 324         }
 325
 326         write_unlock_bh(&x25_neigh_list_lock);
 327 }
 328
 329 /*
 330  *      Given a device, return the neighbour address.
 331  */
 332 struct x25_neigh *x25_get_neigh(struct net_device *dev)
 333 {
 334         struct x25_neigh *nb, *use = NULL;
 335
 336         read_lock_bh(&x25_neigh_list_lock);
 337         list_for_each_entry(nb, &x25_neigh_list, node) {
 338                 if (nb->dev == dev) {
 339                         use = nb;
 340                         break;
 341                 }
 342         }
 343
 344         if (use)
 345                 x25_neigh_hold(use);
 346         read_unlock_bh(&x25_neigh_list_lock);
 347         return use;
 348 }
 349
 350 /*
 351  *      Handle the ioctls that control the subscription functions.
 352  */
 353 int x25_subscr_ioctl(unsigned int cmd, void __user *arg)
 354 {
 355         struct x25_subscrip_struct x25_subscr;
 356         struct x25_neigh *nb;
 357         struct net_device *dev;
 358         int rc = -EINVAL;
 359
 360         if (cmd != SIOCX25GSUBSCRIP && cmd != SIOCX25SSUBSCRIP)
 361                 goto out;
 362
 363         rc = -EFAULT;
 364         if (copy_from_user(&x25_subscr, arg, sizeof(x25_subscr)))
 365                 goto out;
 366
 367         rc = -EINVAL;
 368         if ((dev = x25_dev_get(x25_subscr.device)) == NULL)
 369                 goto out;
 370
 371         if ((nb = x25_get_neigh(dev)) == NULL)
 372                 goto out_dev_put;
 373
 374         dev_put(dev);
 375
 376         if (cmd == SIOCX25GSUBSCRIP) {
 377                 read_lock_bh(&x25_neigh_list_lock);
 378                 x25_subscr.extended          = nb->extended;
 379                 x25_subscr.global_facil_mask = nb->global_facil_mask;
 380                 read_unlock_bh(&x25_neigh_list_lock);
 381                 rc = copy_to_user(arg, &x25_subscr,
 382                                   sizeof(x25_subscr)) ? -EFAULT : 0;
 383         } else {
 384                 rc = -EINVAL;
 385                 if (!(x25_subscr.extended && x25_subscr.extended != 1)) {
 386                         rc = 0;
 387                         write_lock_bh(&x25_neigh_list_lock);
 388                         nb->extended         = x25_subscr.extended;
 389                         nb->global_facil_mask = x25_subscr.global_facil_mask;
 390                         write_unlock_bh(&x25_neigh_list_lock);
 391                 }
 392         }
 393         x25_neigh_put(nb);
 394 out:
 395         return rc;
 396 out_dev_put:
 397         dev_put(dev);
 398         goto out;
 399 }
 400
 401
 402 /*
 403  *      Release all memory associated with X.25 neighbour structures.
 404  */
 405 void __exit x25_link_free(void)
 406 {
 407         struct x25_neigh *nb;
 408         struct list_head *entry, *tmp;
 409
 410         write_lock_bh(&x25_neigh_list_lock);
 411
 412         list_for_each_safe(entry, tmp, &x25_neigh_list) {
 413                 struct net_device *dev;
 414
 415                 nb = list_entry(entry, struct x25_neigh, node);
 416                 dev = nb->dev;
 417                 __x25_remove_neigh(nb);
 418                 dev_put(dev);
 419         }
 420         write_unlock_bh(&x25_neigh_list_lock);
 421 }