1 /* 2 * slip.c This module implements the SLIP protocol for kernel-based 3 * devices like TTY. It interfaces between a raw TTY, and the 4 * kernel's INET protocol layers. 5 * 6 * Version: @(#)slip.c 0.8.3 12/24/94 7 * 8 * Authors: Laurence Culhane, <loz@holmes.demon.co.uk> 9 * Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org> 10 * 11 * Fixes: 12 * Alan Cox : Sanity checks and avoid tx overruns. 13 * Has a new sl->mtu field. 14 * Alan Cox : Found cause of overrun. ifconfig sl0 15 * mtu upwards. Driver now spots this 16 * and grows/shrinks its buffers(hack!). 17 * Memory leak if you run out of memory 18 * setting up a slip driver fixed. 19 * Matt Dillon : Printable slip (borrowed from NET2E) 20 * Pauline Middelink : Slip driver fixes. 21 * Alan Cox : Honours the old SL_COMPRESSED flag 22 * Alan Cox : KISS AX.25 and AXUI IP support 23 * Michael Riepe : Automatic CSLIP recognition added 24 * Charles Hedrick : CSLIP header length problem fix. 25 * Alan Cox : Corrected non-IP cases of the above. 26 * Alan Cox : Now uses hardware type as per FvK. 27 * Alan Cox : Default to 192.168.0.0 (RFC 1597) 28 * A.N.Kuznetsov : dev_tint() recursion fix. 29 * Dmitry Gorodchanin : SLIP memory leaks 30 * Dmitry Gorodchanin : Code cleanup. Reduce tty driver 31 * buffering from 4096 to 256 bytes. 32 * Improving SLIP response time. 33 * CONFIG_SLIP_MODE_SLIP6. 34 * ifconfig sl? up & down now works 35 * correctly. 36 * Modularization. 37 * Alan Cox : Oops - fix AX.25 buffer lengths 38 * Dmitry Gorodchanin : Even more cleanups. Preserve CSLIP 39 * statistics. Include CSLIP code only 40 * if it really needed. 41 * Alan Cox : Free slhc buffers in the right place. 42 * Alan Cox : Allow for digipeated IP over AX.25 43 * Matti Aarnio : Dynamic SLIP devices, with ideas taken 44 * from Jim Freeman's <jfree@caldera.com> 45 * dynamic PPP devices. We do NOT kfree() 46 * device entries, just reg./unreg. them 47 * as they are needed. We kfree() them 48 * at module cleanup. 49 * With MODULE-loading ``insmod'', user 50 * can issue parameter: slip_maxdev=1024 51 * (Or how much he/she wants.. Default 52 * is 256) 53 * Stanislav Voronyi : Slip line checking, with ideas taken 54 * from multislip BSDI driver which was 55 * written by Igor Chechik, RELCOM Corp. 56 * Only algorithms have been ported to 57 * Linux SLIP driver. 58 * Vitaly E. Lavrov : Sane behaviour on tty hangup. 59 * Alexey Kuznetsov : Cleanup interfaces to tty & netdevice 60 * modules. 61 */ 62 63 #define SL_CHECK_TRANSMIT 64 #include <linux/module.h> 65 #include <linux/moduleparam.h> 66 67 #include <asm/uaccess.h> 68 #include <linux/bitops.h> 69 #include <linux/sched.h> 70 #include <linux/string.h> 71 #include <linux/mm.h> 72 #include <linux/interrupt.h> 73 #include <linux/in.h> 74 #include <linux/tty.h> 75 #include <linux/errno.h> 76 #include <linux/netdevice.h> 77 #include <linux/etherdevice.h> 78 #include <linux/skbuff.h> 79 #include <linux/rtnetlink.h> 80 #include <linux/if_arp.h> 81 #include <linux/if_slip.h> 82 #include <linux/compat.h> 83 #include <linux/delay.h> 84 #include <linux/init.h> 85 #include <linux/slab.h> 86 #include "slip.h" 87 #ifdef CONFIG_INET 88 #include <linux/ip.h> 89 #include <linux/tcp.h> 90 #include <net/slhc_vj.h> 91 #endif 92 93 #define SLIP_VERSION "0.8.4-NET3.019-NEWTTY" 94 95 static struct net_device **slip_devs; 96 97 static int slip_maxdev = SL_NRUNIT; 98 module_param(slip_maxdev, int, 0); 99 MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices"); 100 101 static int slip_esc(unsigned char *p, unsigned char *d, int len); 102 static void slip_unesc(struct slip *sl, unsigned char c); 103 #ifdef CONFIG_SLIP_MODE_SLIP6 104 static int slip_esc6(unsigned char *p, unsigned char *d, int len); 105 static void slip_unesc6(struct slip *sl, unsigned char c); 106 #endif 107 #ifdef CONFIG_SLIP_SMART 108 static void sl_keepalive(unsigned long sls); 109 static void sl_outfill(unsigned long sls); 110 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd); 111 #endif 112 113 /******************************** 114 * Buffer administration routines: 115 * sl_alloc_bufs() 116 * sl_free_bufs() 117 * sl_realloc_bufs() 118 * 119 * NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because 120 * sl_realloc_bufs provides strong atomicity and reallocation 121 * on actively running device. 122 *********************************/ 123 124 /* 125 Allocate channel buffers. 126 */ 127 128 static int sl_alloc_bufs(struct slip *sl, int mtu) 129 { 130 int err = -ENOBUFS; 131 unsigned long len; 132 char *rbuff = NULL; 133 char *xbuff = NULL; 134 #ifdef SL_INCLUDE_CSLIP 135 char *cbuff = NULL; 136 struct slcompress *slcomp = NULL; 137 #endif 138 139 /* 140 * Allocate the SLIP frame buffers: 141 * 142 * rbuff Receive buffer. 143 * xbuff Transmit buffer. 144 * cbuff Temporary compression buffer. 145 */ 146 len = mtu * 2; 147 148 /* 149 * allow for arrival of larger UDP packets, even if we say not to 150 * also fixes a bug in which SunOS sends 512-byte packets even with 151 * an MSS of 128 152 */ 153 if (len < 576 * 2) 154 len = 576 * 2; 155 rbuff = kmalloc(len + 4, GFP_KERNEL); 156 if (rbuff == NULL) 157 goto err_exit; 158 xbuff = kmalloc(len + 4, GFP_KERNEL); 159 if (xbuff == NULL) 160 goto err_exit; 161 #ifdef SL_INCLUDE_CSLIP 162 cbuff = kmalloc(len + 4, GFP_KERNEL); 163 if (cbuff == NULL) 164 goto err_exit; 165 slcomp = slhc_init(16, 16); 166 if (slcomp == NULL) 167 goto err_exit; 168 #endif 169 spin_lock_bh(&sl->lock); 170 if (sl->tty == NULL) { 171 spin_unlock_bh(&sl->lock); 172 err = -ENODEV; 173 goto err_exit; 174 } 175 sl->mtu = mtu; 176 sl->buffsize = len; 177 sl->rcount = 0; 178 sl->xleft = 0; 179 rbuff = xchg(&sl->rbuff, rbuff); 180 xbuff = xchg(&sl->xbuff, xbuff); 181 #ifdef SL_INCLUDE_CSLIP 182 cbuff = xchg(&sl->cbuff, cbuff); 183 slcomp = xchg(&sl->slcomp, slcomp); 184 #endif 185 #ifdef CONFIG_SLIP_MODE_SLIP6 186 sl->xdata = 0; 187 sl->xbits = 0; 188 #endif 189 spin_unlock_bh(&sl->lock); 190 err = 0; 191 192 /* Cleanup */ 193 err_exit: 194 #ifdef SL_INCLUDE_CSLIP 195 kfree(cbuff); 196 slhc_free(slcomp); 197 #endif 198 kfree(xbuff); 199 kfree(rbuff); 200 return err; 201 } 202 203 /* Free a SLIP channel buffers. */ 204 static void sl_free_bufs(struct slip *sl) 205 { 206 /* Free all SLIP frame buffers. */ 207 kfree(xchg(&sl->rbuff, NULL)); 208 kfree(xchg(&sl->xbuff, NULL)); 209 #ifdef SL_INCLUDE_CSLIP 210 kfree(xchg(&sl->cbuff, NULL)); 211 slhc_free(xchg(&sl->slcomp, NULL)); 212 #endif 213 } 214 215 /* 216 Reallocate slip channel buffers. 217 */ 218 219 static int sl_realloc_bufs(struct slip *sl, int mtu) 220 { 221 int err = 0; 222 struct net_device *dev = sl->dev; 223 unsigned char *xbuff, *rbuff; 224 #ifdef SL_INCLUDE_CSLIP 225 unsigned char *cbuff; 226 #endif 227 int len = mtu * 2; 228 229 /* 230 * allow for arrival of larger UDP packets, even if we say not to 231 * also fixes a bug in which SunOS sends 512-byte packets even with 232 * an MSS of 128 233 */ 234 if (len < 576 * 2) 235 len = 576 * 2; 236 237 xbuff = kmalloc(len + 4, GFP_ATOMIC); 238 rbuff = kmalloc(len + 4, GFP_ATOMIC); 239 #ifdef SL_INCLUDE_CSLIP 240 cbuff = kmalloc(len + 4, GFP_ATOMIC); 241 #endif 242 243 244 #ifdef SL_INCLUDE_CSLIP 245 if (xbuff == NULL || rbuff == NULL || cbuff == NULL) { 246 #else 247 if (xbuff == NULL || rbuff == NULL) { 248 #endif 249 if (mtu > sl->mtu) { 250 printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n", 251 dev->name); 252 err = -ENOBUFS; 253 } 254 goto done; 255 } 256 spin_lock_bh(&sl->lock); 257 258 err = -ENODEV; 259 if (sl->tty == NULL) 260 goto done_on_bh; 261 262 xbuff = xchg(&sl->xbuff, xbuff); 263 rbuff = xchg(&sl->rbuff, rbuff); 264 #ifdef SL_INCLUDE_CSLIP 265 cbuff = xchg(&sl->cbuff, cbuff); 266 #endif 267 if (sl->xleft) { 268 if (sl->xleft <= len) { 269 memcpy(sl->xbuff, sl->xhead, sl->xleft); 270 } else { 271 sl->xleft = 0; 272 dev->stats.tx_dropped++; 273 } 274 } 275 sl->xhead = sl->xbuff; 276 277 if (sl->rcount) { 278 if (sl->rcount <= len) { 279 memcpy(sl->rbuff, rbuff, sl->rcount); 280 } else { 281 sl->rcount = 0; 282 dev->stats.rx_over_errors++; 283 set_bit(SLF_ERROR, &sl->flags); 284 } 285 } 286 sl->mtu = mtu; 287 dev->mtu = mtu; 288 sl->buffsize = len; 289 err = 0; 290 291 done_on_bh: 292 spin_unlock_bh(&sl->lock); 293 294 done: 295 kfree(xbuff); 296 kfree(rbuff); 297 #ifdef SL_INCLUDE_CSLIP 298 kfree(cbuff); 299 #endif 300 return err; 301 } 302 303 304 /* Set the "sending" flag. This must be atomic hence the set_bit. */ 305 static inline void sl_lock(struct slip *sl) 306 { 307 netif_stop_queue(sl->dev); 308 } 309 310 311 /* Clear the "sending" flag. This must be atomic, hence the ASM. */ 312 static inline void sl_unlock(struct slip *sl) 313 { 314 netif_wake_queue(sl->dev); 315 } 316 317 /* Send one completely decapsulated IP datagram to the IP layer. */ 318 static void sl_bump(struct slip *sl) 319 { 320 struct net_device *dev = sl->dev; 321 struct sk_buff *skb; 322 int count; 323 324 count = sl->rcount; 325 #ifdef SL_INCLUDE_CSLIP 326 if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) { 327 unsigned char c = sl->rbuff[0]; 328 if (c & SL_TYPE_COMPRESSED_TCP) { 329 /* ignore compressed packets when CSLIP is off */ 330 if (!(sl->mode & SL_MODE_CSLIP)) { 331 printk(KERN_WARNING "%s: compressed packet ignored\n", dev->name); 332 return; 333 } 334 /* make sure we've reserved enough space for uncompress 335 to use */ 336 if (count + 80 > sl->buffsize) { 337 dev->stats.rx_over_errors++; 338 return; 339 } 340 count = slhc_uncompress(sl->slcomp, sl->rbuff, count); 341 if (count <= 0) 342 return; 343 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) { 344 if (!(sl->mode & SL_MODE_CSLIP)) { 345 /* turn on header compression */ 346 sl->mode |= SL_MODE_CSLIP; 347 sl->mode &= ~SL_MODE_ADAPTIVE; 348 printk(KERN_INFO "%s: header compression turned on\n", dev->name); 349 } 350 sl->rbuff[0] &= 0x4f; 351 if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0) 352 return; 353 } 354 } 355 #endif /* SL_INCLUDE_CSLIP */ 356 357 dev->stats.rx_bytes += count; 358 359 skb = dev_alloc_skb(count); 360 if (skb == NULL) { 361 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", dev->name); 362 dev->stats.rx_dropped++; 363 return; 364 } 365 skb->dev = dev; 366 memcpy(skb_put(skb, count), sl->rbuff, count); 367 skb_reset_mac_header(skb); 368 skb->protocol = htons(ETH_P_IP); 369 netif_rx_ni(skb); 370 dev->stats.rx_packets++; 371 } 372 373 /* Encapsulate one IP datagram and stuff into a TTY queue. */ 374 static void sl_encaps(struct slip *sl, unsigned char *icp, int len) 375 { 376 unsigned char *p; 377 int actual, count; 378 379 if (len > sl->mtu) { /* Sigh, shouldn't occur BUT ... */ 380 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name); 381 sl->dev->stats.tx_dropped++; 382 sl_unlock(sl); 383 return; 384 } 385 386 p = icp; 387 #ifdef SL_INCLUDE_CSLIP 388 if (sl->mode & SL_MODE_CSLIP) 389 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1); 390 #endif 391 #ifdef CONFIG_SLIP_MODE_SLIP6 392 if (sl->mode & SL_MODE_SLIP6) 393 count = slip_esc6(p, sl->xbuff, len); 394 else 395 #endif 396 count = slip_esc(p, sl->xbuff, len); 397 398 /* Order of next two lines is *very* important. 399 * When we are sending a little amount of data, 400 * the transfer may be completed inside the ops->write() 401 * routine, because it's running with interrupts enabled. 402 * In this case we *never* got WRITE_WAKEUP event, 403 * if we did not request it before write operation. 404 * 14 Oct 1994 Dmitry Gorodchanin. 405 */ 406 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 407 actual = sl->tty->ops->write(sl->tty, sl->xbuff, count); 408 #ifdef SL_CHECK_TRANSMIT 409 sl->dev->trans_start = jiffies; 410 #endif 411 sl->xleft = count - actual; 412 sl->xhead = sl->xbuff + actual; 413 #ifdef CONFIG_SLIP_SMART 414 /* VSV */ 415 clear_bit(SLF_OUTWAIT, &sl->flags); /* reset outfill flag */ 416 #endif 417 } 418 419 /* 420 * Called by the driver when there's room for more data. If we have 421 * more packets to send, we send them here. 422 */ 423 static void slip_write_wakeup(struct tty_struct *tty) 424 { 425 int actual; 426 struct slip *sl = tty->disc_data; 427 428 /* First make sure we're connected. */ 429 if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) 430 return; 431 432 spin_lock(&sl->lock); 433 if (sl->xleft <= 0) { 434 /* Now serial buffer is almost free & we can start 435 * transmission of another packet */ 436 sl->dev->stats.tx_packets++; 437 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 438 spin_unlock(&sl->lock); 439 sl_unlock(sl); 440 return; 441 } 442 443 actual = tty->ops->write(tty, sl->xhead, sl->xleft); 444 sl->xleft -= actual; 445 sl->xhead += actual; 446 spin_unlock(&sl->lock); 447 } 448 449 static void sl_tx_timeout(struct net_device *dev) 450 { 451 struct slip *sl = netdev_priv(dev); 452 453 spin_lock(&sl->lock); 454 455 if (netif_queue_stopped(dev)) { 456 if (!netif_running(dev)) 457 goto out; 458 459 /* May be we must check transmitter timeout here ? 460 * 14 Oct 1994 Dmitry Gorodchanin. 461 */ 462 #ifdef SL_CHECK_TRANSMIT 463 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ)) { 464 /* 20 sec timeout not reached */ 465 goto out; 466 } 467 printk(KERN_WARNING "%s: transmit timed out, %s?\n", 468 dev->name, 469 (tty_chars_in_buffer(sl->tty) || sl->xleft) ? 470 "bad line quality" : "driver error"); 471 sl->xleft = 0; 472 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 473 sl_unlock(sl); 474 #endif 475 } 476 out: 477 spin_unlock(&sl->lock); 478 } 479 480 481 /* Encapsulate an IP datagram and kick it into a TTY queue. */ 482 static netdev_tx_t 483 sl_xmit(struct sk_buff *skb, struct net_device *dev) 484 { 485 struct slip *sl = netdev_priv(dev); 486 487 spin_lock(&sl->lock); 488 if (!netif_running(dev)) { 489 spin_unlock(&sl->lock); 490 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name); 491 dev_kfree_skb(skb); 492 return NETDEV_TX_OK; 493 } 494 if (sl->tty == NULL) { 495 spin_unlock(&sl->lock); 496 dev_kfree_skb(skb); 497 return NETDEV_TX_OK; 498 } 499 500 sl_lock(sl); 501 dev->stats.tx_bytes += skb->len; 502 sl_encaps(sl, skb->data, skb->len); 503 spin_unlock(&sl->lock); 504 505 dev_kfree_skb(skb); 506 return NETDEV_TX_OK; 507 } 508 509 510 /****************************************** 511 * Routines looking at netdevice side. 512 ******************************************/ 513 514 /* Netdevice UP -> DOWN routine */ 515 516 static int 517 sl_close(struct net_device *dev) 518 { 519 struct slip *sl = netdev_priv(dev); 520 521 spin_lock_bh(&sl->lock); 522 if (sl->tty) 523 /* TTY discipline is running. */ 524 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 525 netif_stop_queue(dev); 526 sl->rcount = 0; 527 sl->xleft = 0; 528 spin_unlock_bh(&sl->lock); 529 530 return 0; 531 } 532 533 /* Netdevice DOWN -> UP routine */ 534 535 static int sl_open(struct net_device *dev) 536 { 537 struct slip *sl = netdev_priv(dev); 538 539 if (sl->tty == NULL) 540 return -ENODEV; 541 542 sl->flags &= (1 << SLF_INUSE); 543 netif_start_queue(dev); 544 return 0; 545 } 546 547 /* Netdevice change MTU request */ 548 549 static int sl_change_mtu(struct net_device *dev, int new_mtu) 550 { 551 struct slip *sl = netdev_priv(dev); 552 553 if (new_mtu < 68 || new_mtu > 65534) 554 return -EINVAL; 555 556 if (new_mtu != dev->mtu) 557 return sl_realloc_bufs(sl, new_mtu); 558 return 0; 559 } 560 561 /* Netdevice get statistics request */ 562 563 static struct rtnl_link_stats64 * 564 sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats) 565 { 566 struct net_device_stats *devstats = &dev->stats; 567 #ifdef SL_INCLUDE_CSLIP 568 struct slip *sl = netdev_priv(dev); 569 struct slcompress *comp = sl->slcomp; 570 #endif 571 stats->rx_packets = devstats->rx_packets; 572 stats->tx_packets = devstats->tx_packets; 573 stats->rx_bytes = devstats->rx_bytes; 574 stats->tx_bytes = devstats->tx_bytes; 575 stats->rx_dropped = devstats->rx_dropped; 576 stats->tx_dropped = devstats->tx_dropped; 577 stats->tx_errors = devstats->tx_errors; 578 stats->rx_errors = devstats->rx_errors; 579 stats->rx_over_errors = devstats->rx_over_errors; 580 581 #ifdef SL_INCLUDE_CSLIP 582 if (comp) { 583 /* Generic compressed statistics */ 584 stats->rx_compressed = comp->sls_i_compressed; 585 stats->tx_compressed = comp->sls_o_compressed; 586 587 /* Are we really still needs this? */ 588 stats->rx_fifo_errors += comp->sls_i_compressed; 589 stats->rx_dropped += comp->sls_i_tossed; 590 stats->tx_fifo_errors += comp->sls_o_compressed; 591 stats->collisions += comp->sls_o_misses; 592 } 593 #endif 594 return stats; 595 } 596 597 /* Netdevice register callback */ 598 599 static int sl_init(struct net_device *dev) 600 { 601 struct slip *sl = netdev_priv(dev); 602 603 /* 604 * Finish setting up the DEVICE info. 605 */ 606 607 dev->mtu = sl->mtu; 608 dev->type = ARPHRD_SLIP + sl->mode; 609 #ifdef SL_CHECK_TRANSMIT 610 dev->watchdog_timeo = 20*HZ; 611 #endif 612 return 0; 613 } 614 615 616 static void sl_uninit(struct net_device *dev) 617 { 618 struct slip *sl = netdev_priv(dev); 619 620 sl_free_bufs(sl); 621 } 622 623 /* Hook the destructor so we can free slip devices at the right point in time */ 624 static void sl_free_netdev(struct net_device *dev) 625 { 626 int i = dev->base_addr; 627 free_netdev(dev); 628 slip_devs[i] = NULL; 629 } 630 631 static const struct net_device_ops sl_netdev_ops = { 632 .ndo_init = sl_init, 633 .ndo_uninit = sl_uninit, 634 .ndo_open = sl_open, 635 .ndo_stop = sl_close, 636 .ndo_start_xmit = sl_xmit, 637 .ndo_get_stats64 = sl_get_stats64, 638 .ndo_change_mtu = sl_change_mtu, 639 .ndo_tx_timeout = sl_tx_timeout, 640 #ifdef CONFIG_SLIP_SMART 641 .ndo_do_ioctl = sl_ioctl, 642 #endif 643 }; 644 645 646 static void sl_setup(struct net_device *dev) 647 { 648 dev->netdev_ops = &sl_netdev_ops; 649 dev->destructor = sl_free_netdev; 650 651 dev->hard_header_len = 0; 652 dev->addr_len = 0; 653 dev->tx_queue_len = 10; 654 655 /* New-style flags. */ 656 dev->flags = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST; 657 } 658 659 /****************************************** 660 Routines looking at TTY side. 661 ******************************************/ 662 663 664 /* 665 * Handle the 'receiver data ready' interrupt. 666 * This function is called by the 'tty_io' module in the kernel when 667 * a block of SLIP data has been received, which can now be decapsulated 668 * and sent on to some IP layer for further processing. This will not 669 * be re-entered while running but other ldisc functions may be called 670 * in parallel 671 */ 672 673 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp, 674 char *fp, int count) 675 { 676 struct slip *sl = tty->disc_data; 677 678 if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) 679 return; 680 681 /* Read the characters out of the buffer */ 682 while (count--) { 683 if (fp && *fp++) { 684 if (!test_and_set_bit(SLF_ERROR, &sl->flags)) 685 sl->dev->stats.rx_errors++; 686 cp++; 687 continue; 688 } 689 #ifdef CONFIG_SLIP_MODE_SLIP6 690 if (sl->mode & SL_MODE_SLIP6) 691 slip_unesc6(sl, *cp++); 692 else 693 #endif 694 slip_unesc(sl, *cp++); 695 } 696 } 697 698 /************************************ 699 * slip_open helper routines. 700 ************************************/ 701 702 /* Collect hanged up channels */ 703 static void sl_sync(void) 704 { 705 int i; 706 struct net_device *dev; 707 struct slip *sl; 708 709 for (i = 0; i < slip_maxdev; i++) { 710 dev = slip_devs[i]; 711 if (dev == NULL) 712 break; 713 714 sl = netdev_priv(dev); 715 if (sl->tty || sl->leased) 716 continue; 717 if (dev->flags & IFF_UP) 718 dev_close(dev); 719 } 720 } 721 722 723 /* Find a free SLIP channel, and link in this `tty' line. */ 724 static struct slip *sl_alloc(dev_t line) 725 { 726 int i; 727 char name[IFNAMSIZ]; 728 struct net_device *dev = NULL; 729 struct slip *sl; 730 731 for (i = 0; i < slip_maxdev; i++) { 732 dev = slip_devs[i]; 733 if (dev == NULL) 734 break; 735 } 736 /* Sorry, too many, all slots in use */ 737 if (i >= slip_maxdev) 738 return NULL; 739 740 sprintf(name, "sl%d", i); 741 dev = alloc_netdev(sizeof(*sl), name, sl_setup); 742 if (!dev) 743 return NULL; 744 745 dev->base_addr = i; 746 sl = netdev_priv(dev); 747 748 /* Initialize channel control data */ 749 sl->magic = SLIP_MAGIC; 750 sl->dev = dev; 751 spin_lock_init(&sl->lock); 752 sl->mode = SL_MODE_DEFAULT; 753 #ifdef CONFIG_SLIP_SMART 754 /* initialize timer_list struct */ 755 init_timer(&sl->keepalive_timer); 756 sl->keepalive_timer.data = (unsigned long)sl; 757 sl->keepalive_timer.function = sl_keepalive; 758 init_timer(&sl->outfill_timer); 759 sl->outfill_timer.data = (unsigned long)sl; 760 sl->outfill_timer.function = sl_outfill; 761 #endif 762 slip_devs[i] = dev; 763 return sl; 764 } 765 766 /* 767 * Open the high-level part of the SLIP channel. 768 * This function is called by the TTY module when the 769 * SLIP line discipline is called for. Because we are 770 * sure the tty line exists, we only have to link it to 771 * a free SLIP channel... 772 * 773 * Called in process context serialized from other ldisc calls. 774 */ 775 776 static int slip_open(struct tty_struct *tty) 777 { 778 struct slip *sl; 779 int err; 780 781 if (!capable(CAP_NET_ADMIN)) 782 return -EPERM; 783 784 if (tty->ops->write == NULL) 785 return -EOPNOTSUPP; 786 787 /* RTnetlink lock is misused here to serialize concurrent 788 opens of slip channels. There are better ways, but it is 789 the simplest one. 790 */ 791 rtnl_lock(); 792 793 /* Collect hanged up channels. */ 794 sl_sync(); 795 796 sl = tty->disc_data; 797 798 err = -EEXIST; 799 /* First make sure we're not already connected. */ 800 if (sl && sl->magic == SLIP_MAGIC) 801 goto err_exit; 802 803 /* OK. Find a free SLIP channel to use. */ 804 err = -ENFILE; 805 sl = sl_alloc(tty_devnum(tty)); 806 if (sl == NULL) 807 goto err_exit; 808 809 sl->tty = tty; 810 tty->disc_data = sl; 811 sl->pid = current->pid; 812 813 if (!test_bit(SLF_INUSE, &sl->flags)) { 814 /* Perform the low-level SLIP initialization. */ 815 err = sl_alloc_bufs(sl, SL_MTU); 816 if (err) 817 goto err_free_chan; 818 819 set_bit(SLF_INUSE, &sl->flags); 820 821 err = register_netdevice(sl->dev); 822 if (err) 823 goto err_free_bufs; 824 } 825 826 #ifdef CONFIG_SLIP_SMART 827 if (sl->keepalive) { 828 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ; 829 add_timer(&sl->keepalive_timer); 830 } 831 if (sl->outfill) { 832 sl->outfill_timer.expires = jiffies + sl->outfill * HZ; 833 add_timer(&sl->outfill_timer); 834 } 835 #endif 836 837 /* Done. We have linked the TTY line to a channel. */ 838 rtnl_unlock(); 839 tty->receive_room = 65536; /* We don't flow control */ 840 841 /* TTY layer expects 0 on success */ 842 return 0; 843 844 err_free_bufs: 845 sl_free_bufs(sl); 846 847 err_free_chan: 848 sl->tty = NULL; 849 tty->disc_data = NULL; 850 clear_bit(SLF_INUSE, &sl->flags); 851 852 err_exit: 853 rtnl_unlock(); 854 855 /* Count references from TTY module */ 856 return err; 857 } 858 859 /* 860 * Close down a SLIP channel. 861 * This means flushing out any pending queues, and then returning. This 862 * call is serialized against other ldisc functions. 863 * 864 * We also use this method fo a hangup event 865 */ 866 867 static void slip_close(struct tty_struct *tty) 868 { 869 struct slip *sl = tty->disc_data; 870 871 /* First make sure we're connected. */ 872 if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty) 873 return; 874 875 tty->disc_data = NULL; 876 sl->tty = NULL; 877 878 /* VSV = very important to remove timers */ 879 #ifdef CONFIG_SLIP_SMART 880 del_timer_sync(&sl->keepalive_timer); 881 del_timer_sync(&sl->outfill_timer); 882 #endif 883 /* Flush network side */ 884 unregister_netdev(sl->dev); 885 /* This will complete via sl_free_netdev */ 886 } 887 888 static int slip_hangup(struct tty_struct *tty) 889 { 890 slip_close(tty); 891 return 0; 892 } 893 /************************************************************************ 894 * STANDARD SLIP ENCAPSULATION * 895 ************************************************************************/ 896 897 static int slip_esc(unsigned char *s, unsigned char *d, int len) 898 { 899 unsigned char *ptr = d; 900 unsigned char c; 901 902 /* 903 * Send an initial END character to flush out any 904 * data that may have accumulated in the receiver 905 * due to line noise. 906 */ 907 908 *ptr++ = END; 909 910 /* 911 * For each byte in the packet, send the appropriate 912 * character sequence, according to the SLIP protocol. 913 */ 914 915 while (len-- > 0) { 916 switch (c = *s++) { 917 case END: 918 *ptr++ = ESC; 919 *ptr++ = ESC_END; 920 break; 921 case ESC: 922 *ptr++ = ESC; 923 *ptr++ = ESC_ESC; 924 break; 925 default: 926 *ptr++ = c; 927 break; 928 } 929 } 930 *ptr++ = END; 931 return ptr - d; 932 } 933 934 static void slip_unesc(struct slip *sl, unsigned char s) 935 { 936 937 switch (s) { 938 case END: 939 #ifdef CONFIG_SLIP_SMART 940 /* drop keeptest bit = VSV */ 941 if (test_bit(SLF_KEEPTEST, &sl->flags)) 942 clear_bit(SLF_KEEPTEST, &sl->flags); 943 #endif 944 945 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && 946 (sl->rcount > 2)) 947 sl_bump(sl); 948 clear_bit(SLF_ESCAPE, &sl->flags); 949 sl->rcount = 0; 950 return; 951 952 case ESC: 953 set_bit(SLF_ESCAPE, &sl->flags); 954 return; 955 case ESC_ESC: 956 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags)) 957 s = ESC; 958 break; 959 case ESC_END: 960 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags)) 961 s = END; 962 break; 963 } 964 if (!test_bit(SLF_ERROR, &sl->flags)) { 965 if (sl->rcount < sl->buffsize) { 966 sl->rbuff[sl->rcount++] = s; 967 return; 968 } 969 sl->dev->stats.rx_over_errors++; 970 set_bit(SLF_ERROR, &sl->flags); 971 } 972 } 973 974 975 #ifdef CONFIG_SLIP_MODE_SLIP6 976 /************************************************************************ 977 * 6 BIT SLIP ENCAPSULATION * 978 ************************************************************************/ 979 980 static int slip_esc6(unsigned char *s, unsigned char *d, int len) 981 { 982 unsigned char *ptr = d; 983 unsigned char c; 984 int i; 985 unsigned short v = 0; 986 short bits = 0; 987 988 /* 989 * Send an initial END character to flush out any 990 * data that may have accumulated in the receiver 991 * due to line noise. 992 */ 993 994 *ptr++ = 0x70; 995 996 /* 997 * Encode the packet into printable ascii characters 998 */ 999 1000 for (i = 0; i < len; ++i) { 1001 v = (v << 8) | s[i]; 1002 bits += 8; 1003 while (bits >= 6) { 1004 bits -= 6; 1005 c = 0x30 + ((v >> bits) & 0x3F); 1006 *ptr++ = c; 1007 } 1008 } 1009 if (bits) { 1010 c = 0x30 + ((v << (6 - bits)) & 0x3F); 1011 *ptr++ = c; 1012 } 1013 *ptr++ = 0x70; 1014 return ptr - d; 1015 } 1016 1017 static void slip_unesc6(struct slip *sl, unsigned char s) 1018 { 1019 unsigned char c; 1020 1021 if (s == 0x70) { 1022 #ifdef CONFIG_SLIP_SMART 1023 /* drop keeptest bit = VSV */ 1024 if (test_bit(SLF_KEEPTEST, &sl->flags)) 1025 clear_bit(SLF_KEEPTEST, &sl->flags); 1026 #endif 1027 1028 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && 1029 (sl->rcount > 2)) 1030 sl_bump(sl); 1031 sl->rcount = 0; 1032 sl->xbits = 0; 1033 sl->xdata = 0; 1034 } else if (s >= 0x30 && s < 0x70) { 1035 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F); 1036 sl->xbits += 6; 1037 if (sl->xbits >= 8) { 1038 sl->xbits -= 8; 1039 c = (unsigned char)(sl->xdata >> sl->xbits); 1040 if (!test_bit(SLF_ERROR, &sl->flags)) { 1041 if (sl->rcount < sl->buffsize) { 1042 sl->rbuff[sl->rcount++] = c; 1043 return; 1044 } 1045 sl->dev->stats.rx_over_errors++; 1046 set_bit(SLF_ERROR, &sl->flags); 1047 } 1048 } 1049 } 1050 } 1051 #endif /* CONFIG_SLIP_MODE_SLIP6 */ 1052 1053 /* Perform I/O control on an active SLIP channel. */ 1054 static int slip_ioctl(struct tty_struct *tty, struct file *file, 1055 unsigned int cmd, unsigned long arg) 1056 { 1057 struct slip *sl = tty->disc_data; 1058 unsigned int tmp; 1059 int __user *p = (int __user *)arg; 1060 1061 /* First make sure we're connected. */ 1062 if (!sl || sl->magic != SLIP_MAGIC) 1063 return -EINVAL; 1064 1065 switch (cmd) { 1066 case SIOCGIFNAME: 1067 tmp = strlen(sl->dev->name) + 1; 1068 if (copy_to_user((void __user *)arg, sl->dev->name, tmp)) 1069 return -EFAULT; 1070 return 0; 1071 1072 case SIOCGIFENCAP: 1073 if (put_user(sl->mode, p)) 1074 return -EFAULT; 1075 return 0; 1076 1077 case SIOCSIFENCAP: 1078 if (get_user(tmp, p)) 1079 return -EFAULT; 1080 #ifndef SL_INCLUDE_CSLIP 1081 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE)) 1082 return -EINVAL; 1083 #else 1084 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) == 1085 (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) 1086 /* return -EINVAL; */ 1087 tmp &= ~SL_MODE_ADAPTIVE; 1088 #endif 1089 #ifndef CONFIG_SLIP_MODE_SLIP6 1090 if (tmp & SL_MODE_SLIP6) 1091 return -EINVAL; 1092 #endif 1093 sl->mode = tmp; 1094 sl->dev->type = ARPHRD_SLIP + sl->mode; 1095 return 0; 1096 1097 case SIOCSIFHWADDR: 1098 return -EINVAL; 1099 1100 #ifdef CONFIG_SLIP_SMART 1101 /* VSV changes start here */ 1102 case SIOCSKEEPALIVE: 1103 if (get_user(tmp, p)) 1104 return -EFAULT; 1105 if (tmp > 255) /* max for unchar */ 1106 return -EINVAL; 1107 1108 spin_lock_bh(&sl->lock); 1109 if (!sl->tty) { 1110 spin_unlock_bh(&sl->lock); 1111 return -ENODEV; 1112 } 1113 sl->keepalive = (u8)tmp; 1114 if (sl->keepalive != 0) { 1115 mod_timer(&sl->keepalive_timer, 1116 jiffies + sl->keepalive * HZ); 1117 set_bit(SLF_KEEPTEST, &sl->flags); 1118 } else 1119 del_timer(&sl->keepalive_timer); 1120 spin_unlock_bh(&sl->lock); 1121 return 0; 1122 1123 case SIOCGKEEPALIVE: 1124 if (put_user(sl->keepalive, p)) 1125 return -EFAULT; 1126 return 0; 1127 1128 case SIOCSOUTFILL: 1129 if (get_user(tmp, p)) 1130 return -EFAULT; 1131 if (tmp > 255) /* max for unchar */ 1132 return -EINVAL; 1133 spin_lock_bh(&sl->lock); 1134 if (!sl->tty) { 1135 spin_unlock_bh(&sl->lock); 1136 return -ENODEV; 1137 } 1138 sl->outfill = (u8)tmp; 1139 if (sl->outfill != 0) { 1140 mod_timer(&sl->outfill_timer, 1141 jiffies + sl->outfill * HZ); 1142 set_bit(SLF_OUTWAIT, &sl->flags); 1143 } else 1144 del_timer(&sl->outfill_timer); 1145 spin_unlock_bh(&sl->lock); 1146 return 0; 1147 1148 case SIOCGOUTFILL: 1149 if (put_user(sl->outfill, p)) 1150 return -EFAULT; 1151 return 0; 1152 /* VSV changes end */ 1153 #endif 1154 default: 1155 return tty_mode_ioctl(tty, file, cmd, arg); 1156 } 1157 } 1158 1159 #ifdef CONFIG_COMPAT 1160 static long slip_compat_ioctl(struct tty_struct *tty, struct file *file, 1161 unsigned int cmd, unsigned long arg) 1162 { 1163 switch (cmd) { 1164 case SIOCGIFNAME: 1165 case SIOCGIFENCAP: 1166 case SIOCSIFENCAP: 1167 case SIOCSIFHWADDR: 1168 case SIOCSKEEPALIVE: 1169 case SIOCGKEEPALIVE: 1170 case SIOCSOUTFILL: 1171 case SIOCGOUTFILL: 1172 return slip_ioctl(tty, file, cmd, 1173 (unsigned long)compat_ptr(arg)); 1174 } 1175 1176 return -ENOIOCTLCMD; 1177 } 1178 #endif 1179 1180 /* VSV changes start here */ 1181 #ifdef CONFIG_SLIP_SMART 1182 /* function do_ioctl called from net/core/dev.c 1183 to allow get/set outfill/keepalive parameter 1184 by ifconfig */ 1185 1186 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd) 1187 { 1188 struct slip *sl = netdev_priv(dev); 1189 unsigned long *p = (unsigned long *)&rq->ifr_ifru; 1190 1191 if (sl == NULL) /* Allocation failed ?? */ 1192 return -ENODEV; 1193 1194 spin_lock_bh(&sl->lock); 1195 1196 if (!sl->tty) { 1197 spin_unlock_bh(&sl->lock); 1198 return -ENODEV; 1199 } 1200 1201 switch (cmd) { 1202 case SIOCSKEEPALIVE: 1203 /* max for unchar */ 1204 if ((unsigned)*p > 255) { 1205 spin_unlock_bh(&sl->lock); 1206 return -EINVAL; 1207 } 1208 sl->keepalive = (u8)*p; 1209 if (sl->keepalive != 0) { 1210 sl->keepalive_timer.expires = 1211 jiffies + sl->keepalive * HZ; 1212 mod_timer(&sl->keepalive_timer, 1213 jiffies + sl->keepalive * HZ); 1214 set_bit(SLF_KEEPTEST, &sl->flags); 1215 } else 1216 del_timer(&sl->keepalive_timer); 1217 break; 1218 1219 case SIOCGKEEPALIVE: 1220 *p = sl->keepalive; 1221 break; 1222 1223 case SIOCSOUTFILL: 1224 if ((unsigned)*p > 255) { /* max for unchar */ 1225 spin_unlock_bh(&sl->lock); 1226 return -EINVAL; 1227 } 1228 sl->outfill = (u8)*p; 1229 if (sl->outfill != 0) { 1230 mod_timer(&sl->outfill_timer, 1231 jiffies + sl->outfill * HZ); 1232 set_bit(SLF_OUTWAIT, &sl->flags); 1233 } else 1234 del_timer(&sl->outfill_timer); 1235 break; 1236 1237 case SIOCGOUTFILL: 1238 *p = sl->outfill; 1239 break; 1240 1241 case SIOCSLEASE: 1242 /* Resolve race condition, when ioctl'ing hanged up 1243 and opened by another process device. 1244 */ 1245 if (sl->tty != current->signal->tty && 1246 sl->pid != current->pid) { 1247 spin_unlock_bh(&sl->lock); 1248 return -EPERM; 1249 } 1250 sl->leased = 0; 1251 if (*p) 1252 sl->leased = 1; 1253 break; 1254 1255 case SIOCGLEASE: 1256 *p = sl->leased; 1257 } 1258 spin_unlock_bh(&sl->lock); 1259 return 0; 1260 } 1261 #endif 1262 /* VSV changes end */ 1263 1264 static struct tty_ldisc_ops sl_ldisc = { 1265 .owner = THIS_MODULE, 1266 .magic = TTY_LDISC_MAGIC, 1267 .name = "slip", 1268 .open = slip_open, 1269 .close = slip_close, 1270 .hangup = slip_hangup, 1271 .ioctl = slip_ioctl, 1272 #ifdef CONFIG_COMPAT 1273 .compat_ioctl = slip_compat_ioctl, 1274 #endif 1275 .receive_buf = slip_receive_buf, 1276 .write_wakeup = slip_write_wakeup, 1277 }; 1278 1279 static int __init slip_init(void) 1280 { 1281 int status; 1282 1283 if (slip_maxdev < 4) 1284 slip_maxdev = 4; /* Sanity */ 1285 1286 printk(KERN_INFO "SLIP: version %s (dynamic channels, max=%d)" 1287 #ifdef CONFIG_SLIP_MODE_SLIP6 1288 " (6 bit encapsulation enabled)" 1289 #endif 1290 ".\n", 1291 SLIP_VERSION, slip_maxdev); 1292 #if defined(SL_INCLUDE_CSLIP) 1293 printk(KERN_INFO "CSLIP: code copyright 1989 Regents of the University of California.\n"); 1294 #endif 1295 #ifdef CONFIG_SLIP_SMART 1296 printk(KERN_INFO "SLIP linefill/keepalive option.\n"); 1297 #endif 1298 1299 slip_devs = kzalloc(sizeof(struct net_device *)*slip_maxdev, 1300 GFP_KERNEL); 1301 if (!slip_devs) 1302 return -ENOMEM; 1303 1304 /* Fill in our line protocol discipline, and register it */ 1305 status = tty_register_ldisc(N_SLIP, &sl_ldisc); 1306 if (status != 0) { 1307 printk(KERN_ERR "SLIP: can't register line discipline (err = %d)\n", status); 1308 kfree(slip_devs); 1309 } 1310 return status; 1311 } 1312 1313 static void __exit slip_exit(void) 1314 { 1315 int i; 1316 struct net_device *dev; 1317 struct slip *sl; 1318 unsigned long timeout = jiffies + HZ; 1319 int busy = 0; 1320 1321 if (slip_devs == NULL) 1322 return; 1323 1324 /* First of all: check for active disciplines and hangup them. 1325 */ 1326 do { 1327 if (busy) 1328 msleep_interruptible(100); 1329 1330 busy = 0; 1331 for (i = 0; i < slip_maxdev; i++) { 1332 dev = slip_devs[i]; 1333 if (!dev) 1334 continue; 1335 sl = netdev_priv(dev); 1336 spin_lock_bh(&sl->lock); 1337 if (sl->tty) { 1338 busy++; 1339 tty_hangup(sl->tty); 1340 } 1341 spin_unlock_bh(&sl->lock); 1342 } 1343 } while (busy && time_before(jiffies, timeout)); 1344 1345 /* FIXME: hangup is async so we should wait when doing this second 1346 phase */ 1347 1348 for (i = 0; i < slip_maxdev; i++) { 1349 dev = slip_devs[i]; 1350 if (!dev) 1351 continue; 1352 slip_devs[i] = NULL; 1353 1354 sl = netdev_priv(dev); 1355 if (sl->tty) { 1356 printk(KERN_ERR "%s: tty discipline still running\n", 1357 dev->name); 1358 /* Intentionally leak the control block. */ 1359 dev->destructor = NULL; 1360 } 1361 1362 unregister_netdev(dev); 1363 } 1364 1365 kfree(slip_devs); 1366 slip_devs = NULL; 1367 1368 i = tty_unregister_ldisc(N_SLIP); 1369 if (i != 0) 1370 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i); 1371 } 1372 1373 module_init(slip_init); 1374 module_exit(slip_exit); 1375 1376 #ifdef CONFIG_SLIP_SMART 1377 /* 1378 * This is start of the code for multislip style line checking 1379 * added by Stanislav Voronyi. All changes before marked VSV 1380 */ 1381 1382 static void sl_outfill(unsigned long sls) 1383 { 1384 struct slip *sl = (struct slip *)sls; 1385 1386 spin_lock(&sl->lock); 1387 1388 if (sl->tty == NULL) 1389 goto out; 1390 1391 if (sl->outfill) { 1392 if (test_bit(SLF_OUTWAIT, &sl->flags)) { 1393 /* no packets were transmitted, do outfill */ 1394 #ifdef CONFIG_SLIP_MODE_SLIP6 1395 unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END; 1396 #else 1397 unsigned char s = END; 1398 #endif 1399 /* put END into tty queue. Is it right ??? */ 1400 if (!netif_queue_stopped(sl->dev)) { 1401 /* if device busy no outfill */ 1402 sl->tty->ops->write(sl->tty, &s, 1); 1403 } 1404 } else 1405 set_bit(SLF_OUTWAIT, &sl->flags); 1406 1407 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ); 1408 } 1409 out: 1410 spin_unlock(&sl->lock); 1411 } 1412 1413 static void sl_keepalive(unsigned long sls) 1414 { 1415 struct slip *sl = (struct slip *)sls; 1416 1417 spin_lock(&sl->lock); 1418 1419 if (sl->tty == NULL) 1420 goto out; 1421 1422 if (sl->keepalive) { 1423 if (test_bit(SLF_KEEPTEST, &sl->flags)) { 1424 /* keepalive still high :(, we must hangup */ 1425 if (sl->outfill) 1426 /* outfill timer must be deleted too */ 1427 (void)del_timer(&sl->outfill_timer); 1428 printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name); 1429 /* this must hangup tty & close slip */ 1430 tty_hangup(sl->tty); 1431 /* I think we need not something else */ 1432 goto out; 1433 } else 1434 set_bit(SLF_KEEPTEST, &sl->flags); 1435 1436 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ); 1437 } 1438 out: 1439 spin_unlock(&sl->lock); 1440 } 1441 1442 #endif 1443 MODULE_LICENSE("GPL"); 1444 MODULE_ALIAS_LDISC(N_SLIP); 1445