1 /* 2 * This program is free software; you can distribute it and/or modify it 3 * under the terms of the GNU General Public License (Version 2) as 4 * published by the Free Software Foundation. 5 * 6 * This program is distributed in the hope it will be useful, but WITHOUT 7 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 8 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 9 * for more details. 10 * 11 * You should have received a copy of the GNU General Public License along 12 * with this program; if not, see <http://www.gnu.org/licenses/>. 13 * 14 * Copyright (C) Hans Alblas PE1AYX <hans@esrac.ele.tue.nl> 15 * Copyright (C) 2004, 05 Ralf Baechle DL5RB <ralf@linux-mips.org> 16 * Copyright (C) 2004, 05 Thomas Osterried DL9SAU <thomas@x-berg.in-berlin.de> 17 */ 18 #include <linux/module.h> 19 #include <linux/bitops.h> 20 #include <asm/uaccess.h> 21 #include <linux/crc16.h> 22 #include <linux/string.h> 23 #include <linux/mm.h> 24 #include <linux/interrupt.h> 25 #include <linux/in.h> 26 #include <linux/inet.h> 27 #include <linux/slab.h> 28 #include <linux/tty.h> 29 #include <linux/errno.h> 30 #include <linux/netdevice.h> 31 #include <linux/major.h> 32 #include <linux/init.h> 33 #include <linux/rtnetlink.h> 34 #include <linux/etherdevice.h> 35 #include <linux/skbuff.h> 36 #include <linux/if_arp.h> 37 #include <linux/jiffies.h> 38 #include <linux/compat.h> 39 40 #include <net/ax25.h> 41 42 #define AX_MTU 236 43 44 /* SLIP/KISS protocol characters. */ 45 #define END 0300 /* indicates end of frame */ 46 #define ESC 0333 /* indicates byte stuffing */ 47 #define ESC_END 0334 /* ESC ESC_END means END 'data' */ 48 #define ESC_ESC 0335 /* ESC ESC_ESC means ESC 'data' */ 49 50 struct mkiss { 51 struct tty_struct *tty; /* ptr to TTY structure */ 52 struct net_device *dev; /* easy for intr handling */ 53 54 /* These are pointers to the malloc()ed frame buffers. */ 55 spinlock_t buflock;/* lock for rbuf and xbuf */ 56 unsigned char *rbuff; /* receiver buffer */ 57 int rcount; /* received chars counter */ 58 unsigned char *xbuff; /* transmitter buffer */ 59 unsigned char *xhead; /* pointer to next byte to XMIT */ 60 int xleft; /* bytes left in XMIT queue */ 61 62 /* Detailed SLIP statistics. */ 63 int mtu; /* Our mtu (to spot changes!) */ 64 int buffsize; /* Max buffers sizes */ 65 66 unsigned long flags; /* Flag values/ mode etc */ 67 /* long req'd: used by set_bit --RR */ 68 #define AXF_INUSE 0 /* Channel in use */ 69 #define AXF_ESCAPE 1 /* ESC received */ 70 #define AXF_ERROR 2 /* Parity, etc. error */ 71 #define AXF_KEEPTEST 3 /* Keepalive test flag */ 72 #define AXF_OUTWAIT 4 /* is outpacket was flag */ 73 74 int mode; 75 int crcmode; /* MW: for FlexNet, SMACK etc. */ 76 int crcauto; /* CRC auto mode */ 77 78 #define CRC_MODE_NONE 0 79 #define CRC_MODE_FLEX 1 80 #define CRC_MODE_SMACK 2 81 #define CRC_MODE_FLEX_TEST 3 82 #define CRC_MODE_SMACK_TEST 4 83 84 atomic_t refcnt; 85 struct semaphore dead_sem; 86 }; 87 88 /*---------------------------------------------------------------------------*/ 89 90 static const unsigned short crc_flex_table[] = { 91 0x0f87, 0x1e0e, 0x2c95, 0x3d1c, 0x49a3, 0x582a, 0x6ab1, 0x7b38, 92 0x83cf, 0x9246, 0xa0dd, 0xb154, 0xc5eb, 0xd462, 0xe6f9, 0xf770, 93 0x1f06, 0x0e8f, 0x3c14, 0x2d9d, 0x5922, 0x48ab, 0x7a30, 0x6bb9, 94 0x934e, 0x82c7, 0xb05c, 0xa1d5, 0xd56a, 0xc4e3, 0xf678, 0xe7f1, 95 0x2e85, 0x3f0c, 0x0d97, 0x1c1e, 0x68a1, 0x7928, 0x4bb3, 0x5a3a, 96 0xa2cd, 0xb344, 0x81df, 0x9056, 0xe4e9, 0xf560, 0xc7fb, 0xd672, 97 0x3e04, 0x2f8d, 0x1d16, 0x0c9f, 0x7820, 0x69a9, 0x5b32, 0x4abb, 98 0xb24c, 0xa3c5, 0x915e, 0x80d7, 0xf468, 0xe5e1, 0xd77a, 0xc6f3, 99 0x4d83, 0x5c0a, 0x6e91, 0x7f18, 0x0ba7, 0x1a2e, 0x28b5, 0x393c, 100 0xc1cb, 0xd042, 0xe2d9, 0xf350, 0x87ef, 0x9666, 0xa4fd, 0xb574, 101 0x5d02, 0x4c8b, 0x7e10, 0x6f99, 0x1b26, 0x0aaf, 0x3834, 0x29bd, 102 0xd14a, 0xc0c3, 0xf258, 0xe3d1, 0x976e, 0x86e7, 0xb47c, 0xa5f5, 103 0x6c81, 0x7d08, 0x4f93, 0x5e1a, 0x2aa5, 0x3b2c, 0x09b7, 0x183e, 104 0xe0c9, 0xf140, 0xc3db, 0xd252, 0xa6ed, 0xb764, 0x85ff, 0x9476, 105 0x7c00, 0x6d89, 0x5f12, 0x4e9b, 0x3a24, 0x2bad, 0x1936, 0x08bf, 106 0xf048, 0xe1c1, 0xd35a, 0xc2d3, 0xb66c, 0xa7e5, 0x957e, 0x84f7, 107 0x8b8f, 0x9a06, 0xa89d, 0xb914, 0xcdab, 0xdc22, 0xeeb9, 0xff30, 108 0x07c7, 0x164e, 0x24d5, 0x355c, 0x41e3, 0x506a, 0x62f1, 0x7378, 109 0x9b0e, 0x8a87, 0xb81c, 0xa995, 0xdd2a, 0xcca3, 0xfe38, 0xefb1, 110 0x1746, 0x06cf, 0x3454, 0x25dd, 0x5162, 0x40eb, 0x7270, 0x63f9, 111 0xaa8d, 0xbb04, 0x899f, 0x9816, 0xeca9, 0xfd20, 0xcfbb, 0xde32, 112 0x26c5, 0x374c, 0x05d7, 0x145e, 0x60e1, 0x7168, 0x43f3, 0x527a, 113 0xba0c, 0xab85, 0x991e, 0x8897, 0xfc28, 0xeda1, 0xdf3a, 0xceb3, 114 0x3644, 0x27cd, 0x1556, 0x04df, 0x7060, 0x61e9, 0x5372, 0x42fb, 115 0xc98b, 0xd802, 0xea99, 0xfb10, 0x8faf, 0x9e26, 0xacbd, 0xbd34, 116 0x45c3, 0x544a, 0x66d1, 0x7758, 0x03e7, 0x126e, 0x20f5, 0x317c, 117 0xd90a, 0xc883, 0xfa18, 0xeb91, 0x9f2e, 0x8ea7, 0xbc3c, 0xadb5, 118 0x5542, 0x44cb, 0x7650, 0x67d9, 0x1366, 0x02ef, 0x3074, 0x21fd, 119 0xe889, 0xf900, 0xcb9b, 0xda12, 0xaead, 0xbf24, 0x8dbf, 0x9c36, 120 0x64c1, 0x7548, 0x47d3, 0x565a, 0x22e5, 0x336c, 0x01f7, 0x107e, 121 0xf808, 0xe981, 0xdb1a, 0xca93, 0xbe2c, 0xafa5, 0x9d3e, 0x8cb7, 122 0x7440, 0x65c9, 0x5752, 0x46db, 0x3264, 0x23ed, 0x1176, 0x00ff 123 }; 124 125 static unsigned short calc_crc_flex(unsigned char *cp, int size) 126 { 127 unsigned short crc = 0xffff; 128 129 while (size--) 130 crc = (crc << 8) ^ crc_flex_table[((crc >> 8) ^ *cp++) & 0xff]; 131 132 return crc; 133 } 134 135 static int check_crc_flex(unsigned char *cp, int size) 136 { 137 unsigned short crc = 0xffff; 138 139 if (size < 3) 140 return -1; 141 142 while (size--) 143 crc = (crc << 8) ^ crc_flex_table[((crc >> 8) ^ *cp++) & 0xff]; 144 145 if ((crc & 0xffff) != 0x7070) 146 return -1; 147 148 return 0; 149 } 150 151 static int check_crc_16(unsigned char *cp, int size) 152 { 153 unsigned short crc = 0x0000; 154 155 if (size < 3) 156 return -1; 157 158 crc = crc16(0, cp, size); 159 160 if (crc != 0x0000) 161 return -1; 162 163 return 0; 164 } 165 166 /* 167 * Standard encapsulation 168 */ 169 170 static int kiss_esc(unsigned char *s, unsigned char *d, int len) 171 { 172 unsigned char *ptr = d; 173 unsigned char c; 174 175 /* 176 * Send an initial END character to flush out any data that may have 177 * accumulated in the receiver due to line noise. 178 */ 179 180 *ptr++ = END; 181 182 while (len-- > 0) { 183 switch (c = *s++) { 184 case END: 185 *ptr++ = ESC; 186 *ptr++ = ESC_END; 187 break; 188 case ESC: 189 *ptr++ = ESC; 190 *ptr++ = ESC_ESC; 191 break; 192 default: 193 *ptr++ = c; 194 break; 195 } 196 } 197 198 *ptr++ = END; 199 200 return ptr - d; 201 } 202 203 /* 204 * MW: 205 * OK its ugly, but tell me a better solution without copying the 206 * packet to a temporary buffer :-) 207 */ 208 static int kiss_esc_crc(unsigned char *s, unsigned char *d, unsigned short crc, 209 int len) 210 { 211 unsigned char *ptr = d; 212 unsigned char c=0; 213 214 *ptr++ = END; 215 while (len > 0) { 216 if (len > 2) 217 c = *s++; 218 else if (len > 1) 219 c = crc >> 8; 220 else if (len > 0) 221 c = crc & 0xff; 222 223 len--; 224 225 switch (c) { 226 case END: 227 *ptr++ = ESC; 228 *ptr++ = ESC_END; 229 break; 230 case ESC: 231 *ptr++ = ESC; 232 *ptr++ = ESC_ESC; 233 break; 234 default: 235 *ptr++ = c; 236 break; 237 } 238 } 239 *ptr++ = END; 240 241 return ptr - d; 242 } 243 244 /* Send one completely decapsulated AX.25 packet to the AX.25 layer. */ 245 static void ax_bump(struct mkiss *ax) 246 { 247 struct sk_buff *skb; 248 int count; 249 250 spin_lock_bh(&ax->buflock); 251 if (ax->rbuff[0] > 0x0f) { 252 if (ax->rbuff[0] & 0x80) { 253 if (check_crc_16(ax->rbuff, ax->rcount) < 0) { 254 ax->dev->stats.rx_errors++; 255 spin_unlock_bh(&ax->buflock); 256 257 return; 258 } 259 if (ax->crcmode != CRC_MODE_SMACK && ax->crcauto) { 260 printk(KERN_INFO 261 "mkiss: %s: Switching to crc-smack\n", 262 ax->dev->name); 263 ax->crcmode = CRC_MODE_SMACK; 264 } 265 ax->rcount -= 2; 266 *ax->rbuff &= ~0x80; 267 } else if (ax->rbuff[0] & 0x20) { 268 if (check_crc_flex(ax->rbuff, ax->rcount) < 0) { 269 ax->dev->stats.rx_errors++; 270 spin_unlock_bh(&ax->buflock); 271 return; 272 } 273 if (ax->crcmode != CRC_MODE_FLEX && ax->crcauto) { 274 printk(KERN_INFO 275 "mkiss: %s: Switching to crc-flexnet\n", 276 ax->dev->name); 277 ax->crcmode = CRC_MODE_FLEX; 278 } 279 ax->rcount -= 2; 280 281 /* 282 * dl9sau bugfix: the trailling two bytes flexnet crc 283 * will not be passed to the kernel. thus we have to 284 * correct the kissparm signature, because it indicates 285 * a crc but there's none 286 */ 287 *ax->rbuff &= ~0x20; 288 } 289 } 290 291 count = ax->rcount; 292 293 if ((skb = dev_alloc_skb(count)) == NULL) { 294 printk(KERN_ERR "mkiss: %s: memory squeeze, dropping packet.\n", 295 ax->dev->name); 296 ax->dev->stats.rx_dropped++; 297 spin_unlock_bh(&ax->buflock); 298 return; 299 } 300 301 memcpy(skb_put(skb,count), ax->rbuff, count); 302 skb->protocol = ax25_type_trans(skb, ax->dev); 303 netif_rx(skb); 304 ax->dev->stats.rx_packets++; 305 ax->dev->stats.rx_bytes += count; 306 spin_unlock_bh(&ax->buflock); 307 } 308 309 static void kiss_unesc(struct mkiss *ax, unsigned char s) 310 { 311 switch (s) { 312 case END: 313 /* drop keeptest bit = VSV */ 314 if (test_bit(AXF_KEEPTEST, &ax->flags)) 315 clear_bit(AXF_KEEPTEST, &ax->flags); 316 317 if (!test_and_clear_bit(AXF_ERROR, &ax->flags) && (ax->rcount > 2)) 318 ax_bump(ax); 319 320 clear_bit(AXF_ESCAPE, &ax->flags); 321 ax->rcount = 0; 322 return; 323 324 case ESC: 325 set_bit(AXF_ESCAPE, &ax->flags); 326 return; 327 case ESC_ESC: 328 if (test_and_clear_bit(AXF_ESCAPE, &ax->flags)) 329 s = ESC; 330 break; 331 case ESC_END: 332 if (test_and_clear_bit(AXF_ESCAPE, &ax->flags)) 333 s = END; 334 break; 335 } 336 337 spin_lock_bh(&ax->buflock); 338 if (!test_bit(AXF_ERROR, &ax->flags)) { 339 if (ax->rcount < ax->buffsize) { 340 ax->rbuff[ax->rcount++] = s; 341 spin_unlock_bh(&ax->buflock); 342 return; 343 } 344 345 ax->dev->stats.rx_over_errors++; 346 set_bit(AXF_ERROR, &ax->flags); 347 } 348 spin_unlock_bh(&ax->buflock); 349 } 350 351 static int ax_set_mac_address(struct net_device *dev, void *addr) 352 { 353 struct sockaddr_ax25 *sa = addr; 354 355 netif_tx_lock_bh(dev); 356 netif_addr_lock(dev); 357 memcpy(dev->dev_addr, &sa->sax25_call, AX25_ADDR_LEN); 358 netif_addr_unlock(dev); 359 netif_tx_unlock_bh(dev); 360 361 return 0; 362 } 363 364 /*---------------------------------------------------------------------------*/ 365 366 static void ax_changedmtu(struct mkiss *ax) 367 { 368 struct net_device *dev = ax->dev; 369 unsigned char *xbuff, *rbuff, *oxbuff, *orbuff; 370 int len; 371 372 len = dev->mtu * 2; 373 374 /* 375 * allow for arrival of larger UDP packets, even if we say not to 376 * also fixes a bug in which SunOS sends 512-byte packets even with 377 * an MSS of 128 378 */ 379 if (len < 576 * 2) 380 len = 576 * 2; 381 382 xbuff = kmalloc(len + 4, GFP_ATOMIC); 383 rbuff = kmalloc(len + 4, GFP_ATOMIC); 384 385 if (xbuff == NULL || rbuff == NULL) { 386 printk(KERN_ERR "mkiss: %s: unable to grow ax25 buffers, " 387 "MTU change cancelled.\n", 388 ax->dev->name); 389 dev->mtu = ax->mtu; 390 kfree(xbuff); 391 kfree(rbuff); 392 return; 393 } 394 395 spin_lock_bh(&ax->buflock); 396 397 oxbuff = ax->xbuff; 398 ax->xbuff = xbuff; 399 orbuff = ax->rbuff; 400 ax->rbuff = rbuff; 401 402 if (ax->xleft) { 403 if (ax->xleft <= len) { 404 memcpy(ax->xbuff, ax->xhead, ax->xleft); 405 } else { 406 ax->xleft = 0; 407 dev->stats.tx_dropped++; 408 } 409 } 410 411 ax->xhead = ax->xbuff; 412 413 if (ax->rcount) { 414 if (ax->rcount <= len) { 415 memcpy(ax->rbuff, orbuff, ax->rcount); 416 } else { 417 ax->rcount = 0; 418 dev->stats.rx_over_errors++; 419 set_bit(AXF_ERROR, &ax->flags); 420 } 421 } 422 423 ax->mtu = dev->mtu + 73; 424 ax->buffsize = len; 425 426 spin_unlock_bh(&ax->buflock); 427 428 kfree(oxbuff); 429 kfree(orbuff); 430 } 431 432 /* Encapsulate one AX.25 packet and stuff into a TTY queue. */ 433 static void ax_encaps(struct net_device *dev, unsigned char *icp, int len) 434 { 435 struct mkiss *ax = netdev_priv(dev); 436 unsigned char *p; 437 int actual, count; 438 439 if (ax->mtu != ax->dev->mtu + 73) /* Someone has been ifconfigging */ 440 ax_changedmtu(ax); 441 442 if (len > ax->mtu) { /* Sigh, shouldn't occur BUT ... */ 443 len = ax->mtu; 444 printk(KERN_ERR "mkiss: %s: truncating oversized transmit packet!\n", ax->dev->name); 445 dev->stats.tx_dropped++; 446 netif_start_queue(dev); 447 return; 448 } 449 450 p = icp; 451 452 spin_lock_bh(&ax->buflock); 453 if ((*p & 0x0f) != 0) { 454 /* Configuration Command (kissparms(1). 455 * Protocol spec says: never append CRC. 456 * This fixes a very old bug in the linux 457 * kiss driver. -- dl9sau */ 458 switch (*p & 0xff) { 459 case 0x85: 460 /* command from userspace especially for us, 461 * not for delivery to the tnc */ 462 if (len > 1) { 463 int cmd = (p[1] & 0xff); 464 switch(cmd) { 465 case 3: 466 ax->crcmode = CRC_MODE_SMACK; 467 break; 468 case 2: 469 ax->crcmode = CRC_MODE_FLEX; 470 break; 471 case 1: 472 ax->crcmode = CRC_MODE_NONE; 473 break; 474 case 0: 475 default: 476 ax->crcmode = CRC_MODE_SMACK_TEST; 477 cmd = 0; 478 } 479 ax->crcauto = (cmd ? 0 : 1); 480 printk(KERN_INFO "mkiss: %s: crc mode %s %d\n", ax->dev->name, (len) ? "set to" : "is", cmd); 481 } 482 spin_unlock_bh(&ax->buflock); 483 netif_start_queue(dev); 484 485 return; 486 default: 487 count = kiss_esc(p, ax->xbuff, len); 488 } 489 } else { 490 unsigned short crc; 491 switch (ax->crcmode) { 492 case CRC_MODE_SMACK_TEST: 493 ax->crcmode = CRC_MODE_FLEX_TEST; 494 printk(KERN_INFO "mkiss: %s: Trying crc-smack\n", ax->dev->name); 495 // fall through 496 case CRC_MODE_SMACK: 497 *p |= 0x80; 498 crc = swab16(crc16(0, p, len)); 499 count = kiss_esc_crc(p, ax->xbuff, crc, len+2); 500 break; 501 case CRC_MODE_FLEX_TEST: 502 ax->crcmode = CRC_MODE_NONE; 503 printk(KERN_INFO "mkiss: %s: Trying crc-flexnet\n", ax->dev->name); 504 // fall through 505 case CRC_MODE_FLEX: 506 *p |= 0x20; 507 crc = calc_crc_flex(p, len); 508 count = kiss_esc_crc(p, ax->xbuff, crc, len+2); 509 break; 510 511 default: 512 count = kiss_esc(p, ax->xbuff, len); 513 } 514 } 515 spin_unlock_bh(&ax->buflock); 516 517 set_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags); 518 actual = ax->tty->ops->write(ax->tty, ax->xbuff, count); 519 dev->stats.tx_packets++; 520 dev->stats.tx_bytes += actual; 521 522 ax->dev->trans_start = jiffies; 523 ax->xleft = count - actual; 524 ax->xhead = ax->xbuff + actual; 525 } 526 527 /* Encapsulate an AX.25 packet and kick it into a TTY queue. */ 528 static netdev_tx_t ax_xmit(struct sk_buff *skb, struct net_device *dev) 529 { 530 struct mkiss *ax = netdev_priv(dev); 531 532 if (skb->protocol == htons(ETH_P_IP)) 533 return ax25_ip_xmit(skb); 534 535 if (!netif_running(dev)) { 536 printk(KERN_ERR "mkiss: %s: xmit call when iface is down\n", dev->name); 537 return NETDEV_TX_BUSY; 538 } 539 540 if (netif_queue_stopped(dev)) { 541 /* 542 * May be we must check transmitter timeout here ? 543 * 14 Oct 1994 Dmitry Gorodchanin. 544 */ 545 if (time_before(jiffies, dev->trans_start + 20 * HZ)) { 546 /* 20 sec timeout not reached */ 547 return NETDEV_TX_BUSY; 548 } 549 550 printk(KERN_ERR "mkiss: %s: transmit timed out, %s?\n", dev->name, 551 (tty_chars_in_buffer(ax->tty) || ax->xleft) ? 552 "bad line quality" : "driver error"); 553 554 ax->xleft = 0; 555 clear_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags); 556 netif_start_queue(dev); 557 } 558 559 /* We were not busy, so we are now... :-) */ 560 netif_stop_queue(dev); 561 ax_encaps(dev, skb->data, skb->len); 562 kfree_skb(skb); 563 564 return NETDEV_TX_OK; 565 } 566 567 static int ax_open_dev(struct net_device *dev) 568 { 569 struct mkiss *ax = netdev_priv(dev); 570 571 if (ax->tty == NULL) 572 return -ENODEV; 573 574 return 0; 575 } 576 577 /* Open the low-level part of the AX25 channel. Easy! */ 578 static int ax_open(struct net_device *dev) 579 { 580 struct mkiss *ax = netdev_priv(dev); 581 unsigned long len; 582 583 if (ax->tty == NULL) 584 return -ENODEV; 585 586 /* 587 * Allocate the frame buffers: 588 * 589 * rbuff Receive buffer. 590 * xbuff Transmit buffer. 591 */ 592 len = dev->mtu * 2; 593 594 /* 595 * allow for arrival of larger UDP packets, even if we say not to 596 * also fixes a bug in which SunOS sends 512-byte packets even with 597 * an MSS of 128 598 */ 599 if (len < 576 * 2) 600 len = 576 * 2; 601 602 if ((ax->rbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL) 603 goto norbuff; 604 605 if ((ax->xbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL) 606 goto noxbuff; 607 608 ax->mtu = dev->mtu + 73; 609 ax->buffsize = len; 610 ax->rcount = 0; 611 ax->xleft = 0; 612 613 ax->flags &= (1 << AXF_INUSE); /* Clear ESCAPE & ERROR flags */ 614 615 spin_lock_init(&ax->buflock); 616 617 return 0; 618 619 noxbuff: 620 kfree(ax->rbuff); 621 622 norbuff: 623 return -ENOMEM; 624 } 625 626 627 /* Close the low-level part of the AX25 channel. Easy! */ 628 static int ax_close(struct net_device *dev) 629 { 630 struct mkiss *ax = netdev_priv(dev); 631 632 if (ax->tty) 633 clear_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags); 634 635 netif_stop_queue(dev); 636 637 return 0; 638 } 639 640 static const struct net_device_ops ax_netdev_ops = { 641 .ndo_open = ax_open_dev, 642 .ndo_stop = ax_close, 643 .ndo_start_xmit = ax_xmit, 644 .ndo_set_mac_address = ax_set_mac_address, 645 }; 646 647 static void ax_setup(struct net_device *dev) 648 { 649 /* Finish setting up the DEVICE info. */ 650 dev->mtu = AX_MTU; 651 dev->hard_header_len = 0; 652 dev->addr_len = 0; 653 dev->type = ARPHRD_AX25; 654 dev->tx_queue_len = 10; 655 dev->header_ops = &ax25_header_ops; 656 dev->netdev_ops = &ax_netdev_ops; 657 658 659 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); 660 memcpy(dev->dev_addr, &ax25_defaddr, AX25_ADDR_LEN); 661 662 dev->flags = IFF_BROADCAST | IFF_MULTICAST; 663 } 664 665 /* 666 * We have a potential race on dereferencing tty->disc_data, because the tty 667 * layer provides no locking at all - thus one cpu could be running 668 * sixpack_receive_buf while another calls sixpack_close, which zeroes 669 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The 670 * best way to fix this is to use a rwlock in the tty struct, but for now we 671 * use a single global rwlock for all ttys in ppp line discipline. 672 */ 673 static DEFINE_RWLOCK(disc_data_lock); 674 675 static struct mkiss *mkiss_get(struct tty_struct *tty) 676 { 677 struct mkiss *ax; 678 679 read_lock(&disc_data_lock); 680 ax = tty->disc_data; 681 if (ax) 682 atomic_inc(&ax->refcnt); 683 read_unlock(&disc_data_lock); 684 685 return ax; 686 } 687 688 static void mkiss_put(struct mkiss *ax) 689 { 690 if (atomic_dec_and_test(&ax->refcnt)) 691 up(&ax->dead_sem); 692 } 693 694 static int crc_force = 0; /* Can be overridden with insmod */ 695 696 static int mkiss_open(struct tty_struct *tty) 697 { 698 struct net_device *dev; 699 struct mkiss *ax; 700 int err; 701 702 if (!capable(CAP_NET_ADMIN)) 703 return -EPERM; 704 if (tty->ops->write == NULL) 705 return -EOPNOTSUPP; 706 707 dev = alloc_netdev(sizeof(struct mkiss), "ax%d", NET_NAME_UNKNOWN, 708 ax_setup); 709 if (!dev) { 710 err = -ENOMEM; 711 goto out; 712 } 713 714 ax = netdev_priv(dev); 715 ax->dev = dev; 716 717 spin_lock_init(&ax->buflock); 718 atomic_set(&ax->refcnt, 1); 719 sema_init(&ax->dead_sem, 0); 720 721 ax->tty = tty; 722 tty->disc_data = ax; 723 tty->receive_room = 65535; 724 725 tty_driver_flush_buffer(tty); 726 727 /* Restore default settings */ 728 dev->type = ARPHRD_AX25; 729 730 /* Perform the low-level AX25 initialization. */ 731 err = ax_open(ax->dev); 732 if (err) 733 goto out_free_netdev; 734 735 err = register_netdev(dev); 736 if (err) 737 goto out_free_buffers; 738 739 /* after register_netdev() - because else printk smashes the kernel */ 740 switch (crc_force) { 741 case 3: 742 ax->crcmode = CRC_MODE_SMACK; 743 printk(KERN_INFO "mkiss: %s: crc mode smack forced.\n", 744 ax->dev->name); 745 break; 746 case 2: 747 ax->crcmode = CRC_MODE_FLEX; 748 printk(KERN_INFO "mkiss: %s: crc mode flexnet forced.\n", 749 ax->dev->name); 750 break; 751 case 1: 752 ax->crcmode = CRC_MODE_NONE; 753 printk(KERN_INFO "mkiss: %s: crc mode disabled.\n", 754 ax->dev->name); 755 break; 756 case 0: 757 /* fall through */ 758 default: 759 crc_force = 0; 760 printk(KERN_INFO "mkiss: %s: crc mode is auto.\n", 761 ax->dev->name); 762 ax->crcmode = CRC_MODE_SMACK_TEST; 763 } 764 ax->crcauto = (crc_force ? 0 : 1); 765 766 netif_start_queue(dev); 767 768 /* Done. We have linked the TTY line to a channel. */ 769 return 0; 770 771 out_free_buffers: 772 kfree(ax->rbuff); 773 kfree(ax->xbuff); 774 775 out_free_netdev: 776 free_netdev(dev); 777 778 out: 779 return err; 780 } 781 782 static void mkiss_close(struct tty_struct *tty) 783 { 784 struct mkiss *ax; 785 786 write_lock_bh(&disc_data_lock); 787 ax = tty->disc_data; 788 tty->disc_data = NULL; 789 write_unlock_bh(&disc_data_lock); 790 791 if (!ax) 792 return; 793 794 /* 795 * We have now ensured that nobody can start using ap from now on, but 796 * we have to wait for all existing users to finish. 797 */ 798 if (!atomic_dec_and_test(&ax->refcnt)) 799 down(&ax->dead_sem); 800 801 unregister_netdev(ax->dev); 802 803 /* Free all AX25 frame buffers. */ 804 kfree(ax->rbuff); 805 kfree(ax->xbuff); 806 807 ax->tty = NULL; 808 } 809 810 /* Perform I/O control on an active ax25 channel. */ 811 static int mkiss_ioctl(struct tty_struct *tty, struct file *file, 812 unsigned int cmd, unsigned long arg) 813 { 814 struct mkiss *ax = mkiss_get(tty); 815 struct net_device *dev; 816 unsigned int tmp, err; 817 818 /* First make sure we're connected. */ 819 if (ax == NULL) 820 return -ENXIO; 821 dev = ax->dev; 822 823 switch (cmd) { 824 case SIOCGIFNAME: 825 err = copy_to_user((void __user *) arg, ax->dev->name, 826 strlen(ax->dev->name) + 1) ? -EFAULT : 0; 827 break; 828 829 case SIOCGIFENCAP: 830 err = put_user(4, (int __user *) arg); 831 break; 832 833 case SIOCSIFENCAP: 834 if (get_user(tmp, (int __user *) arg)) { 835 err = -EFAULT; 836 break; 837 } 838 839 ax->mode = tmp; 840 dev->addr_len = AX25_ADDR_LEN; 841 dev->hard_header_len = AX25_KISS_HEADER_LEN + 842 AX25_MAX_HEADER_LEN + 3; 843 dev->type = ARPHRD_AX25; 844 845 err = 0; 846 break; 847 848 case SIOCSIFHWADDR: { 849 char addr[AX25_ADDR_LEN]; 850 851 if (copy_from_user(&addr, 852 (void __user *) arg, AX25_ADDR_LEN)) { 853 err = -EFAULT; 854 break; 855 } 856 857 netif_tx_lock_bh(dev); 858 memcpy(dev->dev_addr, addr, AX25_ADDR_LEN); 859 netif_tx_unlock_bh(dev); 860 861 err = 0; 862 break; 863 } 864 default: 865 err = -ENOIOCTLCMD; 866 } 867 868 mkiss_put(ax); 869 870 return err; 871 } 872 873 #ifdef CONFIG_COMPAT 874 static long mkiss_compat_ioctl(struct tty_struct *tty, struct file *file, 875 unsigned int cmd, unsigned long arg) 876 { 877 switch (cmd) { 878 case SIOCGIFNAME: 879 case SIOCGIFENCAP: 880 case SIOCSIFENCAP: 881 case SIOCSIFHWADDR: 882 return mkiss_ioctl(tty, file, cmd, 883 (unsigned long)compat_ptr(arg)); 884 } 885 886 return -ENOIOCTLCMD; 887 } 888 #endif 889 890 /* 891 * Handle the 'receiver data ready' interrupt. 892 * This function is called by the 'tty_io' module in the kernel when 893 * a block of data has been received, which can now be decapsulated 894 * and sent on to the AX.25 layer for further processing. 895 */ 896 static void mkiss_receive_buf(struct tty_struct *tty, const unsigned char *cp, 897 char *fp, int count) 898 { 899 struct mkiss *ax = mkiss_get(tty); 900 901 if (!ax) 902 return; 903 904 /* 905 * Argh! mtu change time! - costs us the packet part received 906 * at the change 907 */ 908 if (ax->mtu != ax->dev->mtu + 73) 909 ax_changedmtu(ax); 910 911 /* Read the characters out of the buffer */ 912 while (count--) { 913 if (fp != NULL && *fp++) { 914 if (!test_and_set_bit(AXF_ERROR, &ax->flags)) 915 ax->dev->stats.rx_errors++; 916 cp++; 917 continue; 918 } 919 920 kiss_unesc(ax, *cp++); 921 } 922 923 mkiss_put(ax); 924 tty_unthrottle(tty); 925 } 926 927 /* 928 * Called by the driver when there's room for more data. If we have 929 * more packets to send, we send them here. 930 */ 931 static void mkiss_write_wakeup(struct tty_struct *tty) 932 { 933 struct mkiss *ax = mkiss_get(tty); 934 int actual; 935 936 if (!ax) 937 return; 938 939 if (ax->xleft <= 0) { 940 /* Now serial buffer is almost free & we can start 941 * transmission of another packet 942 */ 943 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 944 945 netif_wake_queue(ax->dev); 946 goto out; 947 } 948 949 actual = tty->ops->write(tty, ax->xhead, ax->xleft); 950 ax->xleft -= actual; 951 ax->xhead += actual; 952 953 out: 954 mkiss_put(ax); 955 } 956 957 static struct tty_ldisc_ops ax_ldisc = { 958 .owner = THIS_MODULE, 959 .magic = TTY_LDISC_MAGIC, 960 .name = "mkiss", 961 .open = mkiss_open, 962 .close = mkiss_close, 963 .ioctl = mkiss_ioctl, 964 #ifdef CONFIG_COMPAT 965 .compat_ioctl = mkiss_compat_ioctl, 966 #endif 967 .receive_buf = mkiss_receive_buf, 968 .write_wakeup = mkiss_write_wakeup 969 }; 970 971 static const char banner[] __initconst = KERN_INFO \ 972 "mkiss: AX.25 Multikiss, Hans Albas PE1AYX\n"; 973 static const char msg_regfail[] __initconst = KERN_ERR \ 974 "mkiss: can't register line discipline (err = %d)\n"; 975 976 static int __init mkiss_init_driver(void) 977 { 978 int status; 979 980 printk(banner); 981 982 status = tty_register_ldisc(N_AX25, &ax_ldisc); 983 if (status != 0) 984 printk(msg_regfail, status); 985 986 return status; 987 } 988 989 static const char msg_unregfail[] = KERN_ERR \ 990 "mkiss: can't unregister line discipline (err = %d)\n"; 991 992 static void __exit mkiss_exit_driver(void) 993 { 994 int ret; 995 996 if ((ret = tty_unregister_ldisc(N_AX25))) 997 printk(msg_unregfail, ret); 998 } 999 1000 MODULE_AUTHOR("Ralf Baechle DL5RB <ralf@linux-mips.org>"); 1001 MODULE_DESCRIPTION("KISS driver for AX.25 over TTYs"); 1002 module_param(crc_force, int, 0); 1003 MODULE_PARM_DESC(crc_force, "crc [0 = auto | 1 = none | 2 = flexnet | 3 = smack]"); 1004 MODULE_LICENSE("GPL"); 1005 MODULE_ALIAS_LDISC(N_AX25); 1006 1007 module_init(mkiss_init_driver); 1008 module_exit(mkiss_exit_driver); 1009