1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * slip.c This module implements the SLIP protocol for kernel-based 4 * devices like TTY. It interfaces between a raw TTY, and the 5 * kernel's INET protocol layers. 6 * 7 * Version: @(#)slip.c 0.8.3 12/24/94 8 * 9 * Authors: Laurence Culhane, <loz@holmes.demon.co.uk> 10 * Fred N. van Kempen, <waltje@uwalt.nl.mugnet.org> 11 * 12 * Fixes: 13 * Alan Cox : Sanity checks and avoid tx overruns. 14 * Has a new sl->mtu field. 15 * Alan Cox : Found cause of overrun. ifconfig sl0 16 * mtu upwards. Driver now spots this 17 * and grows/shrinks its buffers(hack!). 18 * Memory leak if you run out of memory 19 * setting up a slip driver fixed. 20 * Matt Dillon : Printable slip (borrowed from NET2E) 21 * Pauline Middelink : Slip driver fixes. 22 * Alan Cox : Honours the old SL_COMPRESSED flag 23 * Alan Cox : KISS AX.25 and AXUI IP support 24 * Michael Riepe : Automatic CSLIP recognition added 25 * Charles Hedrick : CSLIP header length problem fix. 26 * Alan Cox : Corrected non-IP cases of the above. 27 * Alan Cox : Now uses hardware type as per FvK. 28 * Alan Cox : Default to 192.168.0.0 (RFC 1597) 29 * A.N.Kuznetsov : dev_tint() recursion fix. 30 * Dmitry Gorodchanin : SLIP memory leaks 31 * Dmitry Gorodchanin : Code cleanup. Reduce tty driver 32 * buffering from 4096 to 256 bytes. 33 * Improving SLIP response time. 34 * CONFIG_SLIP_MODE_SLIP6. 35 * ifconfig sl? up & down now works 36 * correctly. 37 * Modularization. 38 * Alan Cox : Oops - fix AX.25 buffer lengths 39 * Dmitry Gorodchanin : Even more cleanups. Preserve CSLIP 40 * statistics. Include CSLIP code only 41 * if it really needed. 42 * Alan Cox : Free slhc buffers in the right place. 43 * Alan Cox : Allow for digipeated IP over AX.25 44 * Matti Aarnio : Dynamic SLIP devices, with ideas taken 45 * from Jim Freeman's <jfree@caldera.com> 46 * dynamic PPP devices. We do NOT kfree() 47 * device entries, just reg./unreg. them 48 * as they are needed. We kfree() them 49 * at module cleanup. 50 * With MODULE-loading ``insmod'', user 51 * can issue parameter: slip_maxdev=1024 52 * (Or how much he/she wants.. Default 53 * is 256) 54 * Stanislav Voronyi : Slip line checking, with ideas taken 55 * from multislip BSDI driver which was 56 * written by Igor Chechik, RELCOM Corp. 57 * Only algorithms have been ported to 58 * Linux SLIP driver. 59 * Vitaly E. Lavrov : Sane behaviour on tty hangup. 60 * Alexey Kuznetsov : Cleanup interfaces to tty & netdevice 61 * modules. 62 */ 63 64 #define SL_CHECK_TRANSMIT 65 #include <linux/module.h> 66 #include <linux/moduleparam.h> 67 68 #include <linux/uaccess.h> 69 #include <linux/bitops.h> 70 #include <linux/sched/signal.h> 71 #include <linux/string.h> 72 #include <linux/mm.h> 73 #include <linux/interrupt.h> 74 #include <linux/in.h> 75 #include <linux/tty.h> 76 #include <linux/errno.h> 77 #include <linux/netdevice.h> 78 #include <linux/etherdevice.h> 79 #include <linux/skbuff.h> 80 #include <linux/rtnetlink.h> 81 #include <linux/if_arp.h> 82 #include <linux/if_slip.h> 83 #include <linux/delay.h> 84 #include <linux/init.h> 85 #include <linux/slab.h> 86 #include <linux/workqueue.h> 87 #include "slip.h" 88 #ifdef CONFIG_INET 89 #include <linux/ip.h> 90 #include <linux/tcp.h> 91 #include <net/slhc_vj.h> 92 #endif 93 94 #define SLIP_VERSION "0.8.4-NET3.019-NEWTTY" 95 96 static struct net_device **slip_devs; 97 98 static int slip_maxdev = SL_NRUNIT; 99 module_param(slip_maxdev, int, 0); 100 MODULE_PARM_DESC(slip_maxdev, "Maximum number of slip devices"); 101 102 static int slip_esc(unsigned char *p, unsigned char *d, int len); 103 static void slip_unesc(struct slip *sl, unsigned char c); 104 #ifdef CONFIG_SLIP_MODE_SLIP6 105 static int slip_esc6(unsigned char *p, unsigned char *d, int len); 106 static void slip_unesc6(struct slip *sl, unsigned char c); 107 #endif 108 #ifdef CONFIG_SLIP_SMART 109 static void sl_keepalive(struct timer_list *t); 110 static void sl_outfill(struct timer_list *t); 111 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd); 112 #endif 113 114 /******************************** 115 * Buffer administration routines: 116 * sl_alloc_bufs() 117 * sl_free_bufs() 118 * sl_realloc_bufs() 119 * 120 * NOTE: sl_realloc_bufs != sl_free_bufs + sl_alloc_bufs, because 121 * sl_realloc_bufs provides strong atomicity and reallocation 122 * on actively running device. 123 *********************************/ 124 125 /* 126 Allocate channel buffers. 127 */ 128 129 static int sl_alloc_bufs(struct slip *sl, int mtu) 130 { 131 int err = -ENOBUFS; 132 unsigned long len; 133 char *rbuff = NULL; 134 char *xbuff = NULL; 135 #ifdef SL_INCLUDE_CSLIP 136 char *cbuff = NULL; 137 struct slcompress *slcomp = NULL; 138 #endif 139 140 /* 141 * Allocate the SLIP frame buffers: 142 * 143 * rbuff Receive buffer. 144 * xbuff Transmit buffer. 145 * cbuff Temporary compression buffer. 146 */ 147 len = mtu * 2; 148 149 /* 150 * allow for arrival of larger UDP packets, even if we say not to 151 * also fixes a bug in which SunOS sends 512-byte packets even with 152 * an MSS of 128 153 */ 154 if (len < 576 * 2) 155 len = 576 * 2; 156 rbuff = kmalloc(len + 4, GFP_KERNEL); 157 if (rbuff == NULL) 158 goto err_exit; 159 xbuff = kmalloc(len + 4, GFP_KERNEL); 160 if (xbuff == NULL) 161 goto err_exit; 162 #ifdef SL_INCLUDE_CSLIP 163 cbuff = kmalloc(len + 4, GFP_KERNEL); 164 if (cbuff == NULL) 165 goto err_exit; 166 slcomp = slhc_init(16, 16); 167 if (IS_ERR(slcomp)) 168 goto err_exit; 169 #endif 170 spin_lock_bh(&sl->lock); 171 if (sl->tty == NULL) { 172 spin_unlock_bh(&sl->lock); 173 err = -ENODEV; 174 goto err_exit; 175 } 176 sl->mtu = mtu; 177 sl->buffsize = len; 178 sl->rcount = 0; 179 sl->xleft = 0; 180 rbuff = xchg(&sl->rbuff, rbuff); 181 xbuff = xchg(&sl->xbuff, xbuff); 182 #ifdef SL_INCLUDE_CSLIP 183 cbuff = xchg(&sl->cbuff, cbuff); 184 slcomp = xchg(&sl->slcomp, slcomp); 185 #endif 186 #ifdef CONFIG_SLIP_MODE_SLIP6 187 sl->xdata = 0; 188 sl->xbits = 0; 189 #endif 190 spin_unlock_bh(&sl->lock); 191 err = 0; 192 193 /* Cleanup */ 194 err_exit: 195 #ifdef SL_INCLUDE_CSLIP 196 kfree(cbuff); 197 slhc_free(slcomp); 198 #endif 199 kfree(xbuff); 200 kfree(rbuff); 201 return err; 202 } 203 204 /* Free a SLIP channel buffers. */ 205 static void sl_free_bufs(struct slip *sl) 206 { 207 /* Free all SLIP frame buffers. */ 208 kfree(xchg(&sl->rbuff, NULL)); 209 kfree(xchg(&sl->xbuff, NULL)); 210 #ifdef SL_INCLUDE_CSLIP 211 kfree(xchg(&sl->cbuff, NULL)); 212 slhc_free(xchg(&sl->slcomp, NULL)); 213 #endif 214 } 215 216 /* 217 Reallocate slip channel buffers. 218 */ 219 220 static int sl_realloc_bufs(struct slip *sl, int mtu) 221 { 222 int err = 0; 223 struct net_device *dev = sl->dev; 224 unsigned char *xbuff, *rbuff; 225 #ifdef SL_INCLUDE_CSLIP 226 unsigned char *cbuff; 227 #endif 228 int len = mtu * 2; 229 230 /* 231 * allow for arrival of larger UDP packets, even if we say not to 232 * also fixes a bug in which SunOS sends 512-byte packets even with 233 * an MSS of 128 234 */ 235 if (len < 576 * 2) 236 len = 576 * 2; 237 238 xbuff = kmalloc(len + 4, GFP_ATOMIC); 239 rbuff = kmalloc(len + 4, GFP_ATOMIC); 240 #ifdef SL_INCLUDE_CSLIP 241 cbuff = kmalloc(len + 4, GFP_ATOMIC); 242 #endif 243 244 245 #ifdef SL_INCLUDE_CSLIP 246 if (xbuff == NULL || rbuff == NULL || cbuff == NULL) { 247 #else 248 if (xbuff == NULL || rbuff == NULL) { 249 #endif 250 if (mtu > sl->mtu) { 251 printk(KERN_WARNING "%s: unable to grow slip buffers, MTU change cancelled.\n", 252 dev->name); 253 err = -ENOBUFS; 254 } 255 goto done; 256 } 257 spin_lock_bh(&sl->lock); 258 259 err = -ENODEV; 260 if (sl->tty == NULL) 261 goto done_on_bh; 262 263 xbuff = xchg(&sl->xbuff, xbuff); 264 rbuff = xchg(&sl->rbuff, rbuff); 265 #ifdef SL_INCLUDE_CSLIP 266 cbuff = xchg(&sl->cbuff, cbuff); 267 #endif 268 if (sl->xleft) { 269 if (sl->xleft <= len) { 270 memcpy(sl->xbuff, sl->xhead, sl->xleft); 271 } else { 272 sl->xleft = 0; 273 dev->stats.tx_dropped++; 274 } 275 } 276 sl->xhead = sl->xbuff; 277 278 if (sl->rcount) { 279 if (sl->rcount <= len) { 280 memcpy(sl->rbuff, rbuff, sl->rcount); 281 } else { 282 sl->rcount = 0; 283 dev->stats.rx_over_errors++; 284 set_bit(SLF_ERROR, &sl->flags); 285 } 286 } 287 sl->mtu = mtu; 288 dev->mtu = mtu; 289 sl->buffsize = len; 290 err = 0; 291 292 done_on_bh: 293 spin_unlock_bh(&sl->lock); 294 295 done: 296 kfree(xbuff); 297 kfree(rbuff); 298 #ifdef SL_INCLUDE_CSLIP 299 kfree(cbuff); 300 #endif 301 return err; 302 } 303 304 305 /* Set the "sending" flag. This must be atomic hence the set_bit. */ 306 static inline void sl_lock(struct slip *sl) 307 { 308 netif_stop_queue(sl->dev); 309 } 310 311 312 /* Clear the "sending" flag. This must be atomic, hence the ASM. */ 313 static inline void sl_unlock(struct slip *sl) 314 { 315 netif_wake_queue(sl->dev); 316 } 317 318 /* Send one completely decapsulated IP datagram to the IP layer. */ 319 static void sl_bump(struct slip *sl) 320 { 321 struct net_device *dev = sl->dev; 322 struct sk_buff *skb; 323 int count; 324 325 count = sl->rcount; 326 #ifdef SL_INCLUDE_CSLIP 327 if (sl->mode & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) { 328 unsigned char c = sl->rbuff[0]; 329 if (c & SL_TYPE_COMPRESSED_TCP) { 330 /* ignore compressed packets when CSLIP is off */ 331 if (!(sl->mode & SL_MODE_CSLIP)) { 332 printk(KERN_WARNING "%s: compressed packet ignored\n", dev->name); 333 return; 334 } 335 /* make sure we've reserved enough space for uncompress 336 to use */ 337 if (count + 80 > sl->buffsize) { 338 dev->stats.rx_over_errors++; 339 return; 340 } 341 count = slhc_uncompress(sl->slcomp, sl->rbuff, count); 342 if (count <= 0) 343 return; 344 } else if (c >= SL_TYPE_UNCOMPRESSED_TCP) { 345 if (!(sl->mode & SL_MODE_CSLIP)) { 346 /* turn on header compression */ 347 sl->mode |= SL_MODE_CSLIP; 348 sl->mode &= ~SL_MODE_ADAPTIVE; 349 printk(KERN_INFO "%s: header compression turned on\n", dev->name); 350 } 351 sl->rbuff[0] &= 0x4f; 352 if (slhc_remember(sl->slcomp, sl->rbuff, count) <= 0) 353 return; 354 } 355 } 356 #endif /* SL_INCLUDE_CSLIP */ 357 358 dev->stats.rx_bytes += count; 359 360 skb = dev_alloc_skb(count); 361 if (skb == NULL) { 362 printk(KERN_WARNING "%s: memory squeeze, dropping packet.\n", dev->name); 363 dev->stats.rx_dropped++; 364 return; 365 } 366 skb->dev = dev; 367 skb_put_data(skb, sl->rbuff, count); 368 skb_reset_mac_header(skb); 369 skb->protocol = htons(ETH_P_IP); 370 netif_rx_ni(skb); 371 dev->stats.rx_packets++; 372 } 373 374 /* Encapsulate one IP datagram and stuff into a TTY queue. */ 375 static void sl_encaps(struct slip *sl, unsigned char *icp, int len) 376 { 377 unsigned char *p; 378 int actual, count; 379 380 if (len > sl->mtu) { /* Sigh, shouldn't occur BUT ... */ 381 printk(KERN_WARNING "%s: truncating oversized transmit packet!\n", sl->dev->name); 382 sl->dev->stats.tx_dropped++; 383 sl_unlock(sl); 384 return; 385 } 386 387 p = icp; 388 #ifdef SL_INCLUDE_CSLIP 389 if (sl->mode & SL_MODE_CSLIP) 390 len = slhc_compress(sl->slcomp, p, len, sl->cbuff, &p, 1); 391 #endif 392 #ifdef CONFIG_SLIP_MODE_SLIP6 393 if (sl->mode & SL_MODE_SLIP6) 394 count = slip_esc6(p, sl->xbuff, len); 395 else 396 #endif 397 count = slip_esc(p, sl->xbuff, len); 398 399 /* Order of next two lines is *very* important. 400 * When we are sending a little amount of data, 401 * the transfer may be completed inside the ops->write() 402 * routine, because it's running with interrupts enabled. 403 * In this case we *never* got WRITE_WAKEUP event, 404 * if we did not request it before write operation. 405 * 14 Oct 1994 Dmitry Gorodchanin. 406 */ 407 set_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 408 actual = sl->tty->ops->write(sl->tty, sl->xbuff, count); 409 #ifdef SL_CHECK_TRANSMIT 410 netif_trans_update(sl->dev); 411 #endif 412 sl->xleft = count - actual; 413 sl->xhead = sl->xbuff + actual; 414 #ifdef CONFIG_SLIP_SMART 415 /* VSV */ 416 clear_bit(SLF_OUTWAIT, &sl->flags); /* reset outfill flag */ 417 #endif 418 } 419 420 /* Write out any remaining transmit buffer. Scheduled when tty is writable */ 421 static void slip_transmit(struct work_struct *work) 422 { 423 struct slip *sl = container_of(work, struct slip, tx_work); 424 int actual; 425 426 spin_lock_bh(&sl->lock); 427 /* First make sure we're connected. */ 428 if (!sl->tty || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) { 429 spin_unlock_bh(&sl->lock); 430 return; 431 } 432 433 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, &sl->tty->flags); 438 spin_unlock_bh(&sl->lock); 439 sl_unlock(sl); 440 return; 441 } 442 443 actual = sl->tty->ops->write(sl->tty, sl->xhead, sl->xleft); 444 sl->xleft -= actual; 445 sl->xhead += actual; 446 spin_unlock_bh(&sl->lock); 447 } 448 449 /* 450 * Called by the driver when there's room for more data. 451 * Schedule the transmit. 452 */ 453 static void slip_write_wakeup(struct tty_struct *tty) 454 { 455 struct slip *sl; 456 457 rcu_read_lock(); 458 sl = rcu_dereference(tty->disc_data); 459 if (!sl) 460 goto out; 461 462 schedule_work(&sl->tx_work); 463 out: 464 rcu_read_unlock(); 465 } 466 467 static void sl_tx_timeout(struct net_device *dev, unsigned int txqueue) 468 { 469 struct slip *sl = netdev_priv(dev); 470 471 spin_lock(&sl->lock); 472 473 if (netif_queue_stopped(dev)) { 474 if (!netif_running(dev)) 475 goto out; 476 477 /* May be we must check transmitter timeout here ? 478 * 14 Oct 1994 Dmitry Gorodchanin. 479 */ 480 #ifdef SL_CHECK_TRANSMIT 481 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ)) { 482 /* 20 sec timeout not reached */ 483 goto out; 484 } 485 printk(KERN_WARNING "%s: transmit timed out, %s?\n", 486 dev->name, 487 (tty_chars_in_buffer(sl->tty) || sl->xleft) ? 488 "bad line quality" : "driver error"); 489 sl->xleft = 0; 490 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 491 sl_unlock(sl); 492 #endif 493 } 494 out: 495 spin_unlock(&sl->lock); 496 } 497 498 499 /* Encapsulate an IP datagram and kick it into a TTY queue. */ 500 static netdev_tx_t 501 sl_xmit(struct sk_buff *skb, struct net_device *dev) 502 { 503 struct slip *sl = netdev_priv(dev); 504 505 spin_lock(&sl->lock); 506 if (!netif_running(dev)) { 507 spin_unlock(&sl->lock); 508 printk(KERN_WARNING "%s: xmit call when iface is down\n", dev->name); 509 dev_kfree_skb(skb); 510 return NETDEV_TX_OK; 511 } 512 if (sl->tty == NULL) { 513 spin_unlock(&sl->lock); 514 dev_kfree_skb(skb); 515 return NETDEV_TX_OK; 516 } 517 518 sl_lock(sl); 519 dev->stats.tx_bytes += skb->len; 520 sl_encaps(sl, skb->data, skb->len); 521 spin_unlock(&sl->lock); 522 523 dev_kfree_skb(skb); 524 return NETDEV_TX_OK; 525 } 526 527 528 /****************************************** 529 * Routines looking at netdevice side. 530 ******************************************/ 531 532 /* Netdevice UP -> DOWN routine */ 533 534 static int 535 sl_close(struct net_device *dev) 536 { 537 struct slip *sl = netdev_priv(dev); 538 539 spin_lock_bh(&sl->lock); 540 if (sl->tty) 541 /* TTY discipline is running. */ 542 clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); 543 netif_stop_queue(dev); 544 sl->rcount = 0; 545 sl->xleft = 0; 546 spin_unlock_bh(&sl->lock); 547 548 return 0; 549 } 550 551 /* Netdevice DOWN -> UP routine */ 552 553 static int sl_open(struct net_device *dev) 554 { 555 struct slip *sl = netdev_priv(dev); 556 557 if (sl->tty == NULL) 558 return -ENODEV; 559 560 sl->flags &= (1 << SLF_INUSE); 561 netif_start_queue(dev); 562 return 0; 563 } 564 565 /* Netdevice change MTU request */ 566 567 static int sl_change_mtu(struct net_device *dev, int new_mtu) 568 { 569 struct slip *sl = netdev_priv(dev); 570 571 return sl_realloc_bufs(sl, new_mtu); 572 } 573 574 /* Netdevice get statistics request */ 575 576 static void 577 sl_get_stats64(struct net_device *dev, struct rtnl_link_stats64 *stats) 578 { 579 struct net_device_stats *devstats = &dev->stats; 580 #ifdef SL_INCLUDE_CSLIP 581 struct slip *sl = netdev_priv(dev); 582 struct slcompress *comp = sl->slcomp; 583 #endif 584 stats->rx_packets = devstats->rx_packets; 585 stats->tx_packets = devstats->tx_packets; 586 stats->rx_bytes = devstats->rx_bytes; 587 stats->tx_bytes = devstats->tx_bytes; 588 stats->rx_dropped = devstats->rx_dropped; 589 stats->tx_dropped = devstats->tx_dropped; 590 stats->tx_errors = devstats->tx_errors; 591 stats->rx_errors = devstats->rx_errors; 592 stats->rx_over_errors = devstats->rx_over_errors; 593 594 #ifdef SL_INCLUDE_CSLIP 595 if (comp) { 596 /* Generic compressed statistics */ 597 stats->rx_compressed = comp->sls_i_compressed; 598 stats->tx_compressed = comp->sls_o_compressed; 599 600 /* Are we really still needs this? */ 601 stats->rx_fifo_errors += comp->sls_i_compressed; 602 stats->rx_dropped += comp->sls_i_tossed; 603 stats->tx_fifo_errors += comp->sls_o_compressed; 604 stats->collisions += comp->sls_o_misses; 605 } 606 #endif 607 } 608 609 /* Netdevice register callback */ 610 611 static int sl_init(struct net_device *dev) 612 { 613 struct slip *sl = netdev_priv(dev); 614 615 /* 616 * Finish setting up the DEVICE info. 617 */ 618 619 dev->mtu = sl->mtu; 620 dev->type = ARPHRD_SLIP + sl->mode; 621 #ifdef SL_CHECK_TRANSMIT 622 dev->watchdog_timeo = 20*HZ; 623 #endif 624 return 0; 625 } 626 627 628 static void sl_uninit(struct net_device *dev) 629 { 630 struct slip *sl = netdev_priv(dev); 631 632 sl_free_bufs(sl); 633 } 634 635 /* Hook the destructor so we can free slip devices at the right point in time */ 636 static void sl_free_netdev(struct net_device *dev) 637 { 638 int i = dev->base_addr; 639 640 slip_devs[i] = NULL; 641 } 642 643 static const struct net_device_ops sl_netdev_ops = { 644 .ndo_init = sl_init, 645 .ndo_uninit = sl_uninit, 646 .ndo_open = sl_open, 647 .ndo_stop = sl_close, 648 .ndo_start_xmit = sl_xmit, 649 .ndo_get_stats64 = sl_get_stats64, 650 .ndo_change_mtu = sl_change_mtu, 651 .ndo_tx_timeout = sl_tx_timeout, 652 #ifdef CONFIG_SLIP_SMART 653 .ndo_do_ioctl = sl_ioctl, 654 #endif 655 }; 656 657 658 static void sl_setup(struct net_device *dev) 659 { 660 dev->netdev_ops = &sl_netdev_ops; 661 dev->needs_free_netdev = true; 662 dev->priv_destructor = sl_free_netdev; 663 664 dev->hard_header_len = 0; 665 dev->addr_len = 0; 666 dev->tx_queue_len = 10; 667 668 /* MTU range: 68 - 65534 */ 669 dev->min_mtu = 68; 670 dev->max_mtu = 65534; 671 672 /* New-style flags. */ 673 dev->flags = IFF_NOARP|IFF_POINTOPOINT|IFF_MULTICAST; 674 } 675 676 /****************************************** 677 Routines looking at TTY side. 678 ******************************************/ 679 680 681 /* 682 * Handle the 'receiver data ready' interrupt. 683 * This function is called by the 'tty_io' module in the kernel when 684 * a block of SLIP data has been received, which can now be decapsulated 685 * and sent on to some IP layer for further processing. This will not 686 * be re-entered while running but other ldisc functions may be called 687 * in parallel 688 */ 689 690 static void slip_receive_buf(struct tty_struct *tty, const unsigned char *cp, 691 char *fp, int count) 692 { 693 struct slip *sl = tty->disc_data; 694 695 if (!sl || sl->magic != SLIP_MAGIC || !netif_running(sl->dev)) 696 return; 697 698 /* Read the characters out of the buffer */ 699 while (count--) { 700 if (fp && *fp++) { 701 if (!test_and_set_bit(SLF_ERROR, &sl->flags)) 702 sl->dev->stats.rx_errors++; 703 cp++; 704 continue; 705 } 706 #ifdef CONFIG_SLIP_MODE_SLIP6 707 if (sl->mode & SL_MODE_SLIP6) 708 slip_unesc6(sl, *cp++); 709 else 710 #endif 711 slip_unesc(sl, *cp++); 712 } 713 } 714 715 /************************************ 716 * slip_open helper routines. 717 ************************************/ 718 719 /* Collect hanged up channels */ 720 static void sl_sync(void) 721 { 722 int i; 723 struct net_device *dev; 724 struct slip *sl; 725 726 for (i = 0; i < slip_maxdev; i++) { 727 dev = slip_devs[i]; 728 if (dev == NULL) 729 break; 730 731 sl = netdev_priv(dev); 732 if (sl->tty || sl->leased) 733 continue; 734 if (dev->flags & IFF_UP) 735 dev_close(dev); 736 } 737 } 738 739 740 /* Find a free SLIP channel, and link in this `tty' line. */ 741 static struct slip *sl_alloc(void) 742 { 743 int i; 744 char name[IFNAMSIZ]; 745 struct net_device *dev = NULL; 746 struct slip *sl; 747 748 for (i = 0; i < slip_maxdev; i++) { 749 dev = slip_devs[i]; 750 if (dev == NULL) 751 break; 752 } 753 /* Sorry, too many, all slots in use */ 754 if (i >= slip_maxdev) 755 return NULL; 756 757 sprintf(name, "sl%d", i); 758 dev = alloc_netdev(sizeof(*sl), name, NET_NAME_UNKNOWN, sl_setup); 759 if (!dev) 760 return NULL; 761 762 dev->base_addr = i; 763 sl = netdev_priv(dev); 764 765 /* Initialize channel control data */ 766 sl->magic = SLIP_MAGIC; 767 sl->dev = dev; 768 spin_lock_init(&sl->lock); 769 INIT_WORK(&sl->tx_work, slip_transmit); 770 sl->mode = SL_MODE_DEFAULT; 771 #ifdef CONFIG_SLIP_SMART 772 /* initialize timer_list struct */ 773 timer_setup(&sl->keepalive_timer, sl_keepalive, 0); 774 timer_setup(&sl->outfill_timer, sl_outfill, 0); 775 #endif 776 slip_devs[i] = dev; 777 return sl; 778 } 779 780 /* 781 * Open the high-level part of the SLIP channel. 782 * This function is called by the TTY module when the 783 * SLIP line discipline is called for. Because we are 784 * sure the tty line exists, we only have to link it to 785 * a free SLIP channel... 786 * 787 * Called in process context serialized from other ldisc calls. 788 */ 789 790 static int slip_open(struct tty_struct *tty) 791 { 792 struct slip *sl; 793 int err; 794 795 if (!capable(CAP_NET_ADMIN)) 796 return -EPERM; 797 798 if (tty->ops->write == NULL) 799 return -EOPNOTSUPP; 800 801 /* RTnetlink lock is misused here to serialize concurrent 802 opens of slip channels. There are better ways, but it is 803 the simplest one. 804 */ 805 rtnl_lock(); 806 807 /* Collect hanged up channels. */ 808 sl_sync(); 809 810 sl = tty->disc_data; 811 812 err = -EEXIST; 813 /* First make sure we're not already connected. */ 814 if (sl && sl->magic == SLIP_MAGIC) 815 goto err_exit; 816 817 /* OK. Find a free SLIP channel to use. */ 818 err = -ENFILE; 819 sl = sl_alloc(); 820 if (sl == NULL) 821 goto err_exit; 822 823 sl->tty = tty; 824 tty->disc_data = sl; 825 sl->pid = current->pid; 826 827 if (!test_bit(SLF_INUSE, &sl->flags)) { 828 /* Perform the low-level SLIP initialization. */ 829 err = sl_alloc_bufs(sl, SL_MTU); 830 if (err) 831 goto err_free_chan; 832 833 set_bit(SLF_INUSE, &sl->flags); 834 835 err = register_netdevice(sl->dev); 836 if (err) 837 goto err_free_bufs; 838 } 839 840 #ifdef CONFIG_SLIP_SMART 841 if (sl->keepalive) { 842 sl->keepalive_timer.expires = jiffies + sl->keepalive * HZ; 843 add_timer(&sl->keepalive_timer); 844 } 845 if (sl->outfill) { 846 sl->outfill_timer.expires = jiffies + sl->outfill * HZ; 847 add_timer(&sl->outfill_timer); 848 } 849 #endif 850 851 /* Done. We have linked the TTY line to a channel. */ 852 rtnl_unlock(); 853 tty->receive_room = 65536; /* We don't flow control */ 854 855 /* TTY layer expects 0 on success */ 856 return 0; 857 858 err_free_bufs: 859 sl_free_bufs(sl); 860 861 err_free_chan: 862 sl->tty = NULL; 863 tty->disc_data = NULL; 864 clear_bit(SLF_INUSE, &sl->flags); 865 sl_free_netdev(sl->dev); 866 /* do not call free_netdev before rtnl_unlock */ 867 rtnl_unlock(); 868 free_netdev(sl->dev); 869 return err; 870 871 err_exit: 872 rtnl_unlock(); 873 874 /* Count references from TTY module */ 875 return err; 876 } 877 878 /* 879 * Close down a SLIP channel. 880 * This means flushing out any pending queues, and then returning. This 881 * call is serialized against other ldisc functions. 882 * 883 * We also use this method fo a hangup event 884 */ 885 886 static void slip_close(struct tty_struct *tty) 887 { 888 struct slip *sl = tty->disc_data; 889 890 /* First make sure we're connected. */ 891 if (!sl || sl->magic != SLIP_MAGIC || sl->tty != tty) 892 return; 893 894 spin_lock_bh(&sl->lock); 895 rcu_assign_pointer(tty->disc_data, NULL); 896 sl->tty = NULL; 897 spin_unlock_bh(&sl->lock); 898 899 synchronize_rcu(); 900 flush_work(&sl->tx_work); 901 902 /* VSV = very important to remove timers */ 903 #ifdef CONFIG_SLIP_SMART 904 del_timer_sync(&sl->keepalive_timer); 905 del_timer_sync(&sl->outfill_timer); 906 #endif 907 /* Flush network side */ 908 unregister_netdev(sl->dev); 909 /* This will complete via sl_free_netdev */ 910 } 911 912 static int slip_hangup(struct tty_struct *tty) 913 { 914 slip_close(tty); 915 return 0; 916 } 917 /************************************************************************ 918 * STANDARD SLIP ENCAPSULATION * 919 ************************************************************************/ 920 921 static int slip_esc(unsigned char *s, unsigned char *d, int len) 922 { 923 unsigned char *ptr = d; 924 unsigned char c; 925 926 /* 927 * Send an initial END character to flush out any 928 * data that may have accumulated in the receiver 929 * due to line noise. 930 */ 931 932 *ptr++ = END; 933 934 /* 935 * For each byte in the packet, send the appropriate 936 * character sequence, according to the SLIP protocol. 937 */ 938 939 while (len-- > 0) { 940 switch (c = *s++) { 941 case END: 942 *ptr++ = ESC; 943 *ptr++ = ESC_END; 944 break; 945 case ESC: 946 *ptr++ = ESC; 947 *ptr++ = ESC_ESC; 948 break; 949 default: 950 *ptr++ = c; 951 break; 952 } 953 } 954 *ptr++ = END; 955 return ptr - d; 956 } 957 958 static void slip_unesc(struct slip *sl, unsigned char s) 959 { 960 961 switch (s) { 962 case END: 963 #ifdef CONFIG_SLIP_SMART 964 /* drop keeptest bit = VSV */ 965 if (test_bit(SLF_KEEPTEST, &sl->flags)) 966 clear_bit(SLF_KEEPTEST, &sl->flags); 967 #endif 968 969 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && 970 (sl->rcount > 2)) 971 sl_bump(sl); 972 clear_bit(SLF_ESCAPE, &sl->flags); 973 sl->rcount = 0; 974 return; 975 976 case ESC: 977 set_bit(SLF_ESCAPE, &sl->flags); 978 return; 979 case ESC_ESC: 980 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags)) 981 s = ESC; 982 break; 983 case ESC_END: 984 if (test_and_clear_bit(SLF_ESCAPE, &sl->flags)) 985 s = END; 986 break; 987 } 988 if (!test_bit(SLF_ERROR, &sl->flags)) { 989 if (sl->rcount < sl->buffsize) { 990 sl->rbuff[sl->rcount++] = s; 991 return; 992 } 993 sl->dev->stats.rx_over_errors++; 994 set_bit(SLF_ERROR, &sl->flags); 995 } 996 } 997 998 999 #ifdef CONFIG_SLIP_MODE_SLIP6 1000 /************************************************************************ 1001 * 6 BIT SLIP ENCAPSULATION * 1002 ************************************************************************/ 1003 1004 static int slip_esc6(unsigned char *s, unsigned char *d, int len) 1005 { 1006 unsigned char *ptr = d; 1007 unsigned char c; 1008 int i; 1009 unsigned short v = 0; 1010 short bits = 0; 1011 1012 /* 1013 * Send an initial END character to flush out any 1014 * data that may have accumulated in the receiver 1015 * due to line noise. 1016 */ 1017 1018 *ptr++ = 0x70; 1019 1020 /* 1021 * Encode the packet into printable ascii characters 1022 */ 1023 1024 for (i = 0; i < len; ++i) { 1025 v = (v << 8) | s[i]; 1026 bits += 8; 1027 while (bits >= 6) { 1028 bits -= 6; 1029 c = 0x30 + ((v >> bits) & 0x3F); 1030 *ptr++ = c; 1031 } 1032 } 1033 if (bits) { 1034 c = 0x30 + ((v << (6 - bits)) & 0x3F); 1035 *ptr++ = c; 1036 } 1037 *ptr++ = 0x70; 1038 return ptr - d; 1039 } 1040 1041 static void slip_unesc6(struct slip *sl, unsigned char s) 1042 { 1043 unsigned char c; 1044 1045 if (s == 0x70) { 1046 #ifdef CONFIG_SLIP_SMART 1047 /* drop keeptest bit = VSV */ 1048 if (test_bit(SLF_KEEPTEST, &sl->flags)) 1049 clear_bit(SLF_KEEPTEST, &sl->flags); 1050 #endif 1051 1052 if (!test_and_clear_bit(SLF_ERROR, &sl->flags) && 1053 (sl->rcount > 2)) 1054 sl_bump(sl); 1055 sl->rcount = 0; 1056 sl->xbits = 0; 1057 sl->xdata = 0; 1058 } else if (s >= 0x30 && s < 0x70) { 1059 sl->xdata = (sl->xdata << 6) | ((s - 0x30) & 0x3F); 1060 sl->xbits += 6; 1061 if (sl->xbits >= 8) { 1062 sl->xbits -= 8; 1063 c = (unsigned char)(sl->xdata >> sl->xbits); 1064 if (!test_bit(SLF_ERROR, &sl->flags)) { 1065 if (sl->rcount < sl->buffsize) { 1066 sl->rbuff[sl->rcount++] = c; 1067 return; 1068 } 1069 sl->dev->stats.rx_over_errors++; 1070 set_bit(SLF_ERROR, &sl->flags); 1071 } 1072 } 1073 } 1074 } 1075 #endif /* CONFIG_SLIP_MODE_SLIP6 */ 1076 1077 /* Perform I/O control on an active SLIP channel. */ 1078 static int slip_ioctl(struct tty_struct *tty, struct file *file, 1079 unsigned int cmd, unsigned long arg) 1080 { 1081 struct slip *sl = tty->disc_data; 1082 unsigned int tmp; 1083 int __user *p = (int __user *)arg; 1084 1085 /* First make sure we're connected. */ 1086 if (!sl || sl->magic != SLIP_MAGIC) 1087 return -EINVAL; 1088 1089 switch (cmd) { 1090 case SIOCGIFNAME: 1091 tmp = strlen(sl->dev->name) + 1; 1092 if (copy_to_user((void __user *)arg, sl->dev->name, tmp)) 1093 return -EFAULT; 1094 return 0; 1095 1096 case SIOCGIFENCAP: 1097 if (put_user(sl->mode, p)) 1098 return -EFAULT; 1099 return 0; 1100 1101 case SIOCSIFENCAP: 1102 if (get_user(tmp, p)) 1103 return -EFAULT; 1104 #ifndef SL_INCLUDE_CSLIP 1105 if (tmp & (SL_MODE_CSLIP|SL_MODE_ADAPTIVE)) 1106 return -EINVAL; 1107 #else 1108 if ((tmp & (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) == 1109 (SL_MODE_ADAPTIVE | SL_MODE_CSLIP)) 1110 /* return -EINVAL; */ 1111 tmp &= ~SL_MODE_ADAPTIVE; 1112 #endif 1113 #ifndef CONFIG_SLIP_MODE_SLIP6 1114 if (tmp & SL_MODE_SLIP6) 1115 return -EINVAL; 1116 #endif 1117 sl->mode = tmp; 1118 sl->dev->type = ARPHRD_SLIP + sl->mode; 1119 return 0; 1120 1121 case SIOCSIFHWADDR: 1122 return -EINVAL; 1123 1124 #ifdef CONFIG_SLIP_SMART 1125 /* VSV changes start here */ 1126 case SIOCSKEEPALIVE: 1127 if (get_user(tmp, p)) 1128 return -EFAULT; 1129 if (tmp > 255) /* max for unchar */ 1130 return -EINVAL; 1131 1132 spin_lock_bh(&sl->lock); 1133 if (!sl->tty) { 1134 spin_unlock_bh(&sl->lock); 1135 return -ENODEV; 1136 } 1137 sl->keepalive = (u8)tmp; 1138 if (sl->keepalive != 0) { 1139 mod_timer(&sl->keepalive_timer, 1140 jiffies + sl->keepalive * HZ); 1141 set_bit(SLF_KEEPTEST, &sl->flags); 1142 } else 1143 del_timer(&sl->keepalive_timer); 1144 spin_unlock_bh(&sl->lock); 1145 return 0; 1146 1147 case SIOCGKEEPALIVE: 1148 if (put_user(sl->keepalive, p)) 1149 return -EFAULT; 1150 return 0; 1151 1152 case SIOCSOUTFILL: 1153 if (get_user(tmp, p)) 1154 return -EFAULT; 1155 if (tmp > 255) /* max for unchar */ 1156 return -EINVAL; 1157 spin_lock_bh(&sl->lock); 1158 if (!sl->tty) { 1159 spin_unlock_bh(&sl->lock); 1160 return -ENODEV; 1161 } 1162 sl->outfill = (u8)tmp; 1163 if (sl->outfill != 0) { 1164 mod_timer(&sl->outfill_timer, 1165 jiffies + sl->outfill * HZ); 1166 set_bit(SLF_OUTWAIT, &sl->flags); 1167 } else 1168 del_timer(&sl->outfill_timer); 1169 spin_unlock_bh(&sl->lock); 1170 return 0; 1171 1172 case SIOCGOUTFILL: 1173 if (put_user(sl->outfill, p)) 1174 return -EFAULT; 1175 return 0; 1176 /* VSV changes end */ 1177 #endif 1178 default: 1179 return tty_mode_ioctl(tty, file, cmd, arg); 1180 } 1181 } 1182 1183 /* VSV changes start here */ 1184 #ifdef CONFIG_SLIP_SMART 1185 /* function do_ioctl called from net/core/dev.c 1186 to allow get/set outfill/keepalive parameter 1187 by ifconfig */ 1188 1189 static int sl_ioctl(struct net_device *dev, struct ifreq *rq, int cmd) 1190 { 1191 struct slip *sl = netdev_priv(dev); 1192 unsigned long *p = (unsigned long *)&rq->ifr_ifru; 1193 1194 if (sl == NULL) /* Allocation failed ?? */ 1195 return -ENODEV; 1196 1197 spin_lock_bh(&sl->lock); 1198 1199 if (!sl->tty) { 1200 spin_unlock_bh(&sl->lock); 1201 return -ENODEV; 1202 } 1203 1204 switch (cmd) { 1205 case SIOCSKEEPALIVE: 1206 /* max for unchar */ 1207 if ((unsigned)*p > 255) { 1208 spin_unlock_bh(&sl->lock); 1209 return -EINVAL; 1210 } 1211 sl->keepalive = (u8)*p; 1212 if (sl->keepalive != 0) { 1213 sl->keepalive_timer.expires = 1214 jiffies + sl->keepalive * HZ; 1215 mod_timer(&sl->keepalive_timer, 1216 jiffies + sl->keepalive * HZ); 1217 set_bit(SLF_KEEPTEST, &sl->flags); 1218 } else 1219 del_timer(&sl->keepalive_timer); 1220 break; 1221 1222 case SIOCGKEEPALIVE: 1223 *p = sl->keepalive; 1224 break; 1225 1226 case SIOCSOUTFILL: 1227 if ((unsigned)*p > 255) { /* max for unchar */ 1228 spin_unlock_bh(&sl->lock); 1229 return -EINVAL; 1230 } 1231 sl->outfill = (u8)*p; 1232 if (sl->outfill != 0) { 1233 mod_timer(&sl->outfill_timer, 1234 jiffies + sl->outfill * HZ); 1235 set_bit(SLF_OUTWAIT, &sl->flags); 1236 } else 1237 del_timer(&sl->outfill_timer); 1238 break; 1239 1240 case SIOCGOUTFILL: 1241 *p = sl->outfill; 1242 break; 1243 1244 case SIOCSLEASE: 1245 /* Resolve race condition, when ioctl'ing hanged up 1246 and opened by another process device. 1247 */ 1248 if (sl->tty != current->signal->tty && 1249 sl->pid != current->pid) { 1250 spin_unlock_bh(&sl->lock); 1251 return -EPERM; 1252 } 1253 sl->leased = 0; 1254 if (*p) 1255 sl->leased = 1; 1256 break; 1257 1258 case SIOCGLEASE: 1259 *p = sl->leased; 1260 } 1261 spin_unlock_bh(&sl->lock); 1262 return 0; 1263 } 1264 #endif 1265 /* VSV changes end */ 1266 1267 static struct tty_ldisc_ops sl_ldisc = { 1268 .owner = THIS_MODULE, 1269 .magic = TTY_LDISC_MAGIC, 1270 .name = "slip", 1271 .open = slip_open, 1272 .close = slip_close, 1273 .hangup = slip_hangup, 1274 .ioctl = slip_ioctl, 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 = kcalloc(slip_maxdev, sizeof(struct net_device *), 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 } 1359 1360 unregister_netdev(dev); 1361 } 1362 1363 kfree(slip_devs); 1364 slip_devs = NULL; 1365 1366 i = tty_unregister_ldisc(N_SLIP); 1367 if (i != 0) 1368 printk(KERN_ERR "SLIP: can't unregister line discipline (err = %d)\n", i); 1369 } 1370 1371 module_init(slip_init); 1372 module_exit(slip_exit); 1373 1374 #ifdef CONFIG_SLIP_SMART 1375 /* 1376 * This is start of the code for multislip style line checking 1377 * added by Stanislav Voronyi. All changes before marked VSV 1378 */ 1379 1380 static void sl_outfill(struct timer_list *t) 1381 { 1382 struct slip *sl = from_timer(sl, t, outfill_timer); 1383 1384 spin_lock(&sl->lock); 1385 1386 if (sl->tty == NULL) 1387 goto out; 1388 1389 if (sl->outfill) { 1390 if (test_bit(SLF_OUTWAIT, &sl->flags)) { 1391 /* no packets were transmitted, do outfill */ 1392 #ifdef CONFIG_SLIP_MODE_SLIP6 1393 unsigned char s = (sl->mode & SL_MODE_SLIP6)?0x70:END; 1394 #else 1395 unsigned char s = END; 1396 #endif 1397 /* put END into tty queue. Is it right ??? */ 1398 if (!netif_queue_stopped(sl->dev)) { 1399 /* if device busy no outfill */ 1400 sl->tty->ops->write(sl->tty, &s, 1); 1401 } 1402 } else 1403 set_bit(SLF_OUTWAIT, &sl->flags); 1404 1405 mod_timer(&sl->outfill_timer, jiffies+sl->outfill*HZ); 1406 } 1407 out: 1408 spin_unlock(&sl->lock); 1409 } 1410 1411 static void sl_keepalive(struct timer_list *t) 1412 { 1413 struct slip *sl = from_timer(sl, t, keepalive_timer); 1414 1415 spin_lock(&sl->lock); 1416 1417 if (sl->tty == NULL) 1418 goto out; 1419 1420 if (sl->keepalive) { 1421 if (test_bit(SLF_KEEPTEST, &sl->flags)) { 1422 /* keepalive still high :(, we must hangup */ 1423 if (sl->outfill) 1424 /* outfill timer must be deleted too */ 1425 (void)del_timer(&sl->outfill_timer); 1426 printk(KERN_DEBUG "%s: no packets received during keepalive timeout, hangup.\n", sl->dev->name); 1427 /* this must hangup tty & close slip */ 1428 tty_hangup(sl->tty); 1429 /* I think we need not something else */ 1430 goto out; 1431 } else 1432 set_bit(SLF_KEEPTEST, &sl->flags); 1433 1434 mod_timer(&sl->keepalive_timer, jiffies+sl->keepalive*HZ); 1435 } 1436 out: 1437 spin_unlock(&sl->lock); 1438 } 1439 1440 #endif 1441 MODULE_LICENSE("GPL"); 1442 MODULE_ALIAS_LDISC(N_SLIP); 1443