LXR linux/net/x25/x25

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