1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * 4 * Copyright (C) Hans Alblas PE1AYX <hans@esrac.ele.tue.nl> 5 * Copyright (C) 2004, 05 Ralf Baechle DL5RB <ralf@linux-mips.org> 6 * Copyright (C) 2004, 05 Thomas Osterried DL9SAU <thomas@x-berg.in-berlin.de> 7 */ 8 #include <linux/module.h> 9 #include <linux/bitops.h> 10 #include <linux/uaccess.h> 11 #include <linux/crc16.h> 12 #include <linux/string.h> 13 #include <linux/mm.h> 14 #include <linux/interrupt.h> 15 #include <linux/in.h> 16 #include <linux/inet.h> 17 #include <linux/slab.h> 18 #include <linux/tty.h> 19 #include <linux/errno.h> 20 #include <linux/netdevice.h> 21 #include <linux/major.h> 22 #include <linux/init.h> 23 #include <linux/rtnetlink.h> 24 #include <linux/etherdevice.h> 25 #include <linux/skbuff.h> 26 #include <linux/if_arp.h> 27 #include <linux/jiffies.h> 28 #include <linux/refcount.h> 29 30 #include <net/ax25.h> 31 32 #define AX_MTU 236 33 34 /* SLIP/KISS protocol characters. */ 35 #define END 0300 /* indicates end of frame */ 36 #define ESC 0333 /* indicates byte stuffing */ 37 #define ESC_END 0334 /* ESC ESC_END means END 'data' */ 38 #define ESC_ESC 0335 /* ESC ESC_ESC means ESC 'data' */ 39 40 struct mkiss { 41 struct tty_struct *tty; /* ptr to TTY structure */ 42 struct net_device *dev; /* easy for intr handling */ 43 44 /* These are pointers to the malloc()ed frame buffers. */ 45 spinlock_t buflock;/* lock for rbuf and xbuf */ 46 unsigned char *rbuff; /* receiver buffer */ 47 int rcount; /* received chars counter */ 48 unsigned char *xbuff; /* transmitter buffer */ 49 unsigned char *xhead; /* pointer to next byte to XMIT */ 50 int xleft; /* bytes left in XMIT queue */ 51 52 /* Detailed SLIP statistics. */ 53 int mtu; /* Our mtu (to spot changes!) */ 54 int buffsize; /* Max buffers sizes */ 55 56 unsigned long flags; /* Flag values/ mode etc */ 57 /* long req'd: used by set_bit --RR */ 58 #define AXF_INUSE 0 /* Channel in use */ 59 #define AXF_ESCAPE 1 /* ESC received */ 60 #define AXF_ERROR 2 /* Parity, etc. error */ 61 #define AXF_KEEPTEST 3 /* Keepalive test flag */ 62 #define AXF_OUTWAIT 4 /* is outpacket was flag */ 63 64 int mode; 65 int crcmode; /* MW: for FlexNet, SMACK etc. */ 66 int crcauto; /* CRC auto mode */ 67 68 #define CRC_MODE_NONE 0 69 #define CRC_MODE_FLEX 1 70 #define CRC_MODE_SMACK 2 71 #define CRC_MODE_FLEX_TEST 3 72 #define CRC_MODE_SMACK_TEST 4 73 74 refcount_t refcnt; 75 struct completion dead; 76 }; 77 78 /*---------------------------------------------------------------------------*/ 79 80 static const unsigned short crc_flex_table[] = { 81 0x0f87, 0x1e0e, 0x2c95, 0x3d1c, 0x49a3, 0x582a, 0x6ab1, 0x7b38, 82 0x83cf, 0x9246, 0xa0dd, 0xb154, 0xc5eb, 0xd462, 0xe6f9, 0xf770, 83 0x1f06, 0x0e8f, 0x3c14, 0x2d9d, 0x5922, 0x48ab, 0x7a30, 0x6bb9, 84 0x934e, 0x82c7, 0xb05c, 0xa1d5, 0xd56a, 0xc4e3, 0xf678, 0xe7f1, 85 0x2e85, 0x3f0c, 0x0d97, 0x1c1e, 0x68a1, 0x7928, 0x4bb3, 0x5a3a, 86 0xa2cd, 0xb344, 0x81df, 0x9056, 0xe4e9, 0xf560, 0xc7fb, 0xd672, 87 0x3e04, 0x2f8d, 0x1d16, 0x0c9f, 0x7820, 0x69a9, 0x5b32, 0x4abb, 88 0xb24c, 0xa3c5, 0x915e, 0x80d7, 0xf468, 0xe5e1, 0xd77a, 0xc6f3, 89 0x4d83, 0x5c0a, 0x6e91, 0x7f18, 0x0ba7, 0x1a2e, 0x28b5, 0x393c, 90 0xc1cb, 0xd042, 0xe2d9, 0xf350, 0x87ef, 0x9666, 0xa4fd, 0xb574, 91 0x5d02, 0x4c8b, 0x7e10, 0x6f99, 0x1b26, 0x0aaf, 0x3834, 0x29bd, 92 0xd14a, 0xc0c3, 0xf258, 0xe3d1, 0x976e, 0x86e7, 0xb47c, 0xa5f5, 93 0x6c81, 0x7d08, 0x4f93, 0x5e1a, 0x2aa5, 0x3b2c, 0x09b7, 0x183e, 94 0xe0c9, 0xf140, 0xc3db, 0xd252, 0xa6ed, 0xb764, 0x85ff, 0x9476, 95 0x7c00, 0x6d89, 0x5f12, 0x4e9b, 0x3a24, 0x2bad, 0x1936, 0x08bf, 96 0xf048, 0xe1c1, 0xd35a, 0xc2d3, 0xb66c, 0xa7e5, 0x957e, 0x84f7, 97 0x8b8f, 0x9a06, 0xa89d, 0xb914, 0xcdab, 0xdc22, 0xeeb9, 0xff30, 98 0x07c7, 0x164e, 0x24d5, 0x355c, 0x41e3, 0x506a, 0x62f1, 0x7378, 99 0x9b0e, 0x8a87, 0xb81c, 0xa995, 0xdd2a, 0xcca3, 0xfe38, 0xefb1, 100 0x1746, 0x06cf, 0x3454, 0x25dd, 0x5162, 0x40eb, 0x7270, 0x63f9, 101 0xaa8d, 0xbb04, 0x899f, 0x9816, 0xeca9, 0xfd20, 0xcfbb, 0xde32, 102 0x26c5, 0x374c, 0x05d7, 0x145e, 0x60e1, 0x7168, 0x43f3, 0x527a, 103 0xba0c, 0xab85, 0x991e, 0x8897, 0xfc28, 0xeda1, 0xdf3a, 0xceb3, 104 0x3644, 0x27cd, 0x1556, 0x04df, 0x7060, 0x61e9, 0x5372, 0x42fb, 105 0xc98b, 0xd802, 0xea99, 0xfb10, 0x8faf, 0x9e26, 0xacbd, 0xbd34, 106 0x45c3, 0x544a, 0x66d1, 0x7758, 0x03e7, 0x126e, 0x20f5, 0x317c, 107 0xd90a, 0xc883, 0xfa18, 0xeb91, 0x9f2e, 0x8ea7, 0xbc3c, 0xadb5, 108 0x5542, 0x44cb, 0x7650, 0x67d9, 0x1366, 0x02ef, 0x3074, 0x21fd, 109 0xe889, 0xf900, 0xcb9b, 0xda12, 0xaead, 0xbf24, 0x8dbf, 0x9c36, 110 0x64c1, 0x7548, 0x47d3, 0x565a, 0x22e5, 0x336c, 0x01f7, 0x107e, 111 0xf808, 0xe981, 0xdb1a, 0xca93, 0xbe2c, 0xafa5, 0x9d3e, 0x8cb7, 112 0x7440, 0x65c9, 0x5752, 0x46db, 0x3264, 0x23ed, 0x1176, 0x00ff 113 }; 114 115 static unsigned short calc_crc_flex(unsigned char *cp, int size) 116 { 117 unsigned short crc = 0xffff; 118 119 while (size--) 120 crc = (crc << 8) ^ crc_flex_table[((crc >> 8) ^ *cp++) & 0xff]; 121 122 return crc; 123 } 124 125 static int check_crc_flex(unsigned char *cp, int size) 126 { 127 unsigned short crc = 0xffff; 128 129 if (size < 3) 130 return -1; 131 132 while (size--) 133 crc = (crc << 8) ^ crc_flex_table[((crc >> 8) ^ *cp++) & 0xff]; 134 135 if ((crc & 0xffff) != 0x7070) 136 return -1; 137 138 return 0; 139 } 140 141 static int check_crc_16(unsigned char *cp, int size) 142 { 143 unsigned short crc = 0x0000; 144 145 if (size < 3) 146 return -1; 147 148 crc = crc16(0, cp, size); 149 150 if (crc != 0x0000) 151 return -1; 152 153 return 0; 154 } 155 156 /* 157 * Standard encapsulation 158 */ 159 160 static int kiss_esc(unsigned char *s, unsigned char *d, int len) 161 { 162 unsigned char *ptr = d; 163 unsigned char c; 164 165 /* 166 * Send an initial END character to flush out any data that may have 167 * accumulated in the receiver due to line noise. 168 */ 169 170 *ptr++ = END; 171 172 while (len-- > 0) { 173 switch (c = *s++) { 174 case END: 175 *ptr++ = ESC; 176 *ptr++ = ESC_END; 177 break; 178 case ESC: 179 *ptr++ = ESC; 180 *ptr++ = ESC_ESC; 181 break; 182 default: 183 *ptr++ = c; 184 break; 185 } 186 } 187 188 *ptr++ = END; 189 190 return ptr - d; 191 } 192 193 /* 194 * MW: 195 * OK its ugly, but tell me a better solution without copying the 196 * packet to a temporary buffer :-) 197 */ 198 static int kiss_esc_crc(unsigned char *s, unsigned char *d, unsigned short crc, 199 int len) 200 { 201 unsigned char *ptr = d; 202 unsigned char c=0; 203 204 *ptr++ = END; 205 while (len > 0) { 206 if (len > 2) 207 c = *s++; 208 else if (len > 1) 209 c = crc >> 8; 210 else 211 c = crc & 0xff; 212 213 len--; 214 215 switch (c) { 216 case END: 217 *ptr++ = ESC; 218 *ptr++ = ESC_END; 219 break; 220 case ESC: 221 *ptr++ = ESC; 222 *ptr++ = ESC_ESC; 223 break; 224 default: 225 *ptr++ = c; 226 break; 227 } 228 } 229 *ptr++ = END; 230 231 return ptr - d; 232 } 233 234 /* Send one completely decapsulated AX.25 packet to the AX.25 layer. */ 235 static void ax_bump(struct mkiss *ax) 236 { 237 struct sk_buff *skb; 238 int count; 239 240 spin_lock_bh(&ax->buflock); 241 if (ax->rbuff[0] > 0x0f) { 242 if (ax->rbuff[0] & 0x80) { 243 if (check_crc_16(ax->rbuff, ax->rcount) < 0) { 244 ax->dev->stats.rx_errors++; 245 spin_unlock_bh(&ax->buflock); 246 247 return; 248 } 249 if (ax->crcmode != CRC_MODE_SMACK && ax->crcauto) { 250 printk(KERN_INFO 251 "mkiss: %s: Switching to crc-smack\n", 252 ax->dev->name); 253 ax->crcmode = CRC_MODE_SMACK; 254 } 255 ax->rcount -= 2; 256 *ax->rbuff &= ~0x80; 257 } else if (ax->rbuff[0] & 0x20) { 258 if (check_crc_flex(ax->rbuff, ax->rcount) < 0) { 259 ax->dev->stats.rx_errors++; 260 spin_unlock_bh(&ax->buflock); 261 return; 262 } 263 if (ax->crcmode != CRC_MODE_FLEX && ax->crcauto) { 264 printk(KERN_INFO 265 "mkiss: %s: Switching to crc-flexnet\n", 266 ax->dev->name); 267 ax->crcmode = CRC_MODE_FLEX; 268 } 269 ax->rcount -= 2; 270 271 /* 272 * dl9sau bugfix: the trailling two bytes flexnet crc 273 * will not be passed to the kernel. thus we have to 274 * correct the kissparm signature, because it indicates 275 * a crc but there's none 276 */ 277 *ax->rbuff &= ~0x20; 278 } 279 } 280 281 count = ax->rcount; 282 283 if ((skb = dev_alloc_skb(count)) == NULL) { 284 printk(KERN_ERR "mkiss: %s: memory squeeze, dropping packet.\n", 285 ax->dev->name); 286 ax->dev->stats.rx_dropped++; 287 spin_unlock_bh(&ax->buflock); 288 return; 289 } 290 291 skb_put_data(skb, ax->rbuff, count); 292 skb->protocol = ax25_type_trans(skb, ax->dev); 293 netif_rx(skb); 294 ax->dev->stats.rx_packets++; 295 ax->dev->stats.rx_bytes += count; 296 spin_unlock_bh(&ax->buflock); 297 } 298 299 static void kiss_unesc(struct mkiss *ax, unsigned char s) 300 { 301 switch (s) { 302 case END: 303 /* drop keeptest bit = VSV */ 304 if (test_bit(AXF_KEEPTEST, &ax->flags)) 305 clear_bit(AXF_KEEPTEST, &ax->flags); 306 307 if (!test_and_clear_bit(AXF_ERROR, &ax->flags) && (ax->rcount > 2)) 308 ax_bump(ax); 309 310 clear_bit(AXF_ESCAPE, &ax->flags); 311 ax->rcount = 0; 312 return; 313 314 case ESC: 315 set_bit(AXF_ESCAPE, &ax->flags); 316 return; 317 case ESC_ESC: 318 if (test_and_clear_bit(AXF_ESCAPE, &ax->flags)) 319 s = ESC; 320 break; 321 case ESC_END: 322 if (test_and_clear_bit(AXF_ESCAPE, &ax->flags)) 323 s = END; 324 break; 325 } 326 327 spin_lock_bh(&ax->buflock); 328 if (!test_bit(AXF_ERROR, &ax->flags)) { 329 if (ax->rcount < ax->buffsize) { 330 ax->rbuff[ax->rcount++] = s; 331 spin_unlock_bh(&ax->buflock); 332 return; 333 } 334 335 ax->dev->stats.rx_over_errors++; 336 set_bit(AXF_ERROR, &ax->flags); 337 } 338 spin_unlock_bh(&ax->buflock); 339 } 340 341 static int ax_set_mac_address(struct net_device *dev, void *addr) 342 { 343 struct sockaddr_ax25 *sa = addr; 344 345 netif_tx_lock_bh(dev); 346 netif_addr_lock(dev); 347 __dev_addr_set(dev, &sa->sax25_call, AX25_ADDR_LEN); 348 netif_addr_unlock(dev); 349 netif_tx_unlock_bh(dev); 350 351 return 0; 352 } 353 354 /*---------------------------------------------------------------------------*/ 355 356 static void ax_changedmtu(struct mkiss *ax) 357 { 358 struct net_device *dev = ax->dev; 359 unsigned char *xbuff, *rbuff, *oxbuff, *orbuff; 360 int len; 361 362 len = dev->mtu * 2; 363 364 /* 365 * allow for arrival of larger UDP packets, even if we say not to 366 * also fixes a bug in which SunOS sends 512-byte packets even with 367 * an MSS of 128 368 */ 369 if (len < 576 * 2) 370 len = 576 * 2; 371 372 xbuff = kmalloc(len + 4, GFP_ATOMIC); 373 rbuff = kmalloc(len + 4, GFP_ATOMIC); 374 375 if (xbuff == NULL || rbuff == NULL) { 376 printk(KERN_ERR "mkiss: %s: unable to grow ax25 buffers, " 377 "MTU change cancelled.\n", 378 ax->dev->name); 379 dev->mtu = ax->mtu; 380 kfree(xbuff); 381 kfree(rbuff); 382 return; 383 } 384 385 spin_lock_bh(&ax->buflock); 386 387 oxbuff = ax->xbuff; 388 ax->xbuff = xbuff; 389 orbuff = ax->rbuff; 390 ax->rbuff = rbuff; 391 392 if (ax->xleft) { 393 if (ax->xleft <= len) { 394 memcpy(ax->xbuff, ax->xhead, ax->xleft); 395 } else { 396 ax->xleft = 0; 397 dev->stats.tx_dropped++; 398 } 399 } 400 401 ax->xhead = ax->xbuff; 402 403 if (ax->rcount) { 404 if (ax->rcount <= len) { 405 memcpy(ax->rbuff, orbuff, ax->rcount); 406 } else { 407 ax->rcount = 0; 408 dev->stats.rx_over_errors++; 409 set_bit(AXF_ERROR, &ax->flags); 410 } 411 } 412 413 ax->mtu = dev->mtu + 73; 414 ax->buffsize = len; 415 416 spin_unlock_bh(&ax->buflock); 417 418 kfree(oxbuff); 419 kfree(orbuff); 420 } 421 422 /* Encapsulate one AX.25 packet and stuff into a TTY queue. */ 423 static void ax_encaps(struct net_device *dev, unsigned char *icp, int len) 424 { 425 struct mkiss *ax = netdev_priv(dev); 426 unsigned char *p; 427 int actual, count; 428 429 if (ax->mtu != ax->dev->mtu + 73) /* Someone has been ifconfigging */ 430 ax_changedmtu(ax); 431 432 if (len > ax->mtu) { /* Sigh, shouldn't occur BUT ... */ 433 printk(KERN_ERR "mkiss: %s: truncating oversized transmit packet!\n", ax->dev->name); 434 dev->stats.tx_dropped++; 435 netif_start_queue(dev); 436 return; 437 } 438 439 p = icp; 440 441 spin_lock_bh(&ax->buflock); 442 if ((*p & 0x0f) != 0) { 443 /* Configuration Command (kissparms(1). 444 * Protocol spec says: never append CRC. 445 * This fixes a very old bug in the linux 446 * kiss driver. -- dl9sau */ 447 switch (*p & 0xff) { 448 case 0x85: 449 /* command from userspace especially for us, 450 * not for delivery to the tnc */ 451 if (len > 1) { 452 int cmd = (p[1] & 0xff); 453 switch(cmd) { 454 case 3: 455 ax->crcmode = CRC_MODE_SMACK; 456 break; 457 case 2: 458 ax->crcmode = CRC_MODE_FLEX; 459 break; 460 case 1: 461 ax->crcmode = CRC_MODE_NONE; 462 break; 463 case 0: 464 default: 465 ax->crcmode = CRC_MODE_SMACK_TEST; 466 cmd = 0; 467 } 468 ax->crcauto = (cmd ? 0 : 1); 469 printk(KERN_INFO "mkiss: %s: crc mode set to %d\n", 470 ax->dev->name, cmd); 471 } 472 spin_unlock_bh(&ax->buflock); 473 netif_start_queue(dev); 474 475 return; 476 default: 477 count = kiss_esc(p, ax->xbuff, len); 478 } 479 } else { 480 unsigned short crc; 481 switch (ax->crcmode) { 482 case CRC_MODE_SMACK_TEST: 483 ax->crcmode = CRC_MODE_FLEX_TEST; 484 printk(KERN_INFO "mkiss: %s: Trying crc-smack\n", ax->dev->name); 485 fallthrough; 486 case CRC_MODE_SMACK: 487 *p |= 0x80; 488 crc = swab16(crc16(0, p, len)); 489 count = kiss_esc_crc(p, ax->xbuff, crc, len+2); 490 break; 491 case CRC_MODE_FLEX_TEST: 492 ax->crcmode = CRC_MODE_NONE; 493 printk(KERN_INFO "mkiss: %s: Trying crc-flexnet\n", ax->dev->name); 494 fallthrough; 495 case CRC_MODE_FLEX: 496 *p |= 0x20; 497 crc = calc_crc_flex(p, len); 498 count = kiss_esc_crc(p, ax->xbuff, crc, len+2); 499 break; 500 501 default: 502 count = kiss_esc(p, ax->xbuff, len); 503 } 504 } 505 spin_unlock_bh(&ax->buflock); 506 507 set_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags); 508 actual = ax->tty->ops->write(ax->tty, ax->xbuff, count); 509 dev->stats.tx_packets++; 510 dev->stats.tx_bytes += actual; 511 512 netif_trans_update(ax->dev); 513 ax->xleft = count - actual; 514 ax->xhead = ax->xbuff + actual; 515 } 516 517 /* Encapsulate an AX.25 packet and kick it into a TTY queue. */ 518 static netdev_tx_t ax_xmit(struct sk_buff *skb, struct net_device *dev) 519 { 520 struct mkiss *ax = netdev_priv(dev); 521 522 if (skb->protocol == htons(ETH_P_IP)) 523 return ax25_ip_xmit(skb); 524 525 if (!netif_running(dev)) { 526 printk(KERN_ERR "mkiss: %s: xmit call when iface is down\n", dev->name); 527 return NETDEV_TX_BUSY; 528 } 529 530 if (netif_queue_stopped(dev)) { 531 /* 532 * May be we must check transmitter timeout here ? 533 * 14 Oct 1994 Dmitry Gorodchanin. 534 */ 535 if (time_before(jiffies, dev_trans_start(dev) + 20 * HZ)) { 536 /* 20 sec timeout not reached */ 537 return NETDEV_TX_BUSY; 538 } 539 540 printk(KERN_ERR "mkiss: %s: transmit timed out, %s?\n", dev->name, 541 (tty_chars_in_buffer(ax->tty) || ax->xleft) ? 542 "bad line quality" : "driver error"); 543 544 ax->xleft = 0; 545 clear_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags); 546 netif_start_queue(dev); 547 } 548 549 /* We were not busy, so we are now... :-) */ 550 netif_stop_queue(dev); 551 ax_encaps(dev, skb->data, skb->len); 552 kfree_skb(skb); 553 554 return NETDEV_TX_OK; 555 } 556 557 static int ax_open_dev(struct net_device *dev) 558 { 559 struct mkiss *ax = netdev_priv(dev); 560 561 if (ax->tty == NULL) 562 return -ENODEV; 563 564 return 0; 565 } 566 567 /* Open the low-level part of the AX25 channel. Easy! */ 568 static int ax_open(struct net_device *dev) 569 { 570 struct mkiss *ax = netdev_priv(dev); 571 unsigned long len; 572 573 if (ax->tty == NULL) 574 return -ENODEV; 575 576 /* 577 * Allocate the frame buffers: 578 * 579 * rbuff Receive buffer. 580 * xbuff Transmit buffer. 581 */ 582 len = dev->mtu * 2; 583 584 /* 585 * allow for arrival of larger UDP packets, even if we say not to 586 * also fixes a bug in which SunOS sends 512-byte packets even with 587 * an MSS of 128 588 */ 589 if (len < 576 * 2) 590 len = 576 * 2; 591 592 if ((ax->rbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL) 593 goto norbuff; 594 595 if ((ax->xbuff = kmalloc(len + 4, GFP_KERNEL)) == NULL) 596 goto noxbuff; 597 598 ax->mtu = dev->mtu + 73; 599 ax->buffsize = len; 600 ax->rcount = 0; 601 ax->xleft = 0; 602 603 ax->flags &= (1 << AXF_INUSE); /* Clear ESCAPE & ERROR flags */ 604 605 spin_lock_init(&ax->buflock); 606 607 return 0; 608 609 noxbuff: 610 kfree(ax->rbuff); 611 612 norbuff: 613 return -ENOMEM; 614 } 615 616 617 /* Close the low-level part of the AX25 channel. Easy! */ 618 static int ax_close(struct net_device *dev) 619 { 620 struct mkiss *ax = netdev_priv(dev); 621 622 if (ax->tty) 623 clear_bit(TTY_DO_WRITE_WAKEUP, &ax->tty->flags); 624 625 netif_stop_queue(dev); 626 627 return 0; 628 } 629 630 static const struct net_device_ops ax_netdev_ops = { 631 .ndo_open = ax_open_dev, 632 .ndo_stop = ax_close, 633 .ndo_start_xmit = ax_xmit, 634 .ndo_set_mac_address = ax_set_mac_address, 635 }; 636 637 static void ax_setup(struct net_device *dev) 638 { 639 /* Finish setting up the DEVICE info. */ 640 dev->mtu = AX_MTU; 641 dev->hard_header_len = AX25_MAX_HEADER_LEN; 642 dev->addr_len = AX25_ADDR_LEN; 643 dev->type = ARPHRD_AX25; 644 dev->tx_queue_len = 10; 645 dev->header_ops = &ax25_header_ops; 646 dev->netdev_ops = &ax_netdev_ops; 647 648 649 memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN); 650 dev_addr_set(dev, (u8 *)&ax25_defaddr); 651 652 dev->flags = IFF_BROADCAST | IFF_MULTICAST; 653 } 654 655 /* 656 * We have a potential race on dereferencing tty->disc_data, because the tty 657 * layer provides no locking at all - thus one cpu could be running 658 * sixpack_receive_buf while another calls sixpack_close, which zeroes 659 * tty->disc_data and frees the memory that sixpack_receive_buf is using. The 660 * best way to fix this is to use a rwlock in the tty struct, but for now we 661 * use a single global rwlock for all ttys in ppp line discipline. 662 */ 663 static DEFINE_RWLOCK(disc_data_lock); 664 665 static struct mkiss *mkiss_get(struct tty_struct *tty) 666 { 667 struct mkiss *ax; 668 669 read_lock(&disc_data_lock); 670 ax = tty->disc_data; 671 if (ax) 672 refcount_inc(&ax->refcnt); 673 read_unlock(&disc_data_lock); 674 675 return ax; 676 } 677 678 static void mkiss_put(struct mkiss *ax) 679 { 680 if (refcount_dec_and_test(&ax->refcnt)) 681 complete(&ax->dead); 682 } 683 684 static int crc_force = 0; /* Can be overridden with insmod */ 685 686 static int mkiss_open(struct tty_struct *tty) 687 { 688 struct net_device *dev; 689 struct mkiss *ax; 690 int err; 691 692 if (!capable(CAP_NET_ADMIN)) 693 return -EPERM; 694 if (tty->ops->write == NULL) 695 return -EOPNOTSUPP; 696 697 dev = alloc_netdev(sizeof(struct mkiss), "ax%d", NET_NAME_UNKNOWN, 698 ax_setup); 699 if (!dev) { 700 err = -ENOMEM; 701 goto out; 702 } 703 704 ax = netdev_priv(dev); 705 ax->dev = dev; 706 707 spin_lock_init(&ax->buflock); 708 refcount_set(&ax->refcnt, 1); 709 init_completion(&ax->dead); 710 711 ax->tty = tty; 712 tty->disc_data = ax; 713 tty->receive_room = 65535; 714 715 tty_driver_flush_buffer(tty); 716 717 /* Restore default settings */ 718 dev->type = ARPHRD_AX25; 719 720 /* Perform the low-level AX25 initialization. */ 721 err = ax_open(ax->dev); 722 if (err) 723 goto out_free_netdev; 724 725 err = register_netdev(dev); 726 if (err) 727 goto out_free_buffers; 728 729 /* after register_netdev() - because else printk smashes the kernel */ 730 switch (crc_force) { 731 case 3: 732 ax->crcmode = CRC_MODE_SMACK; 733 printk(KERN_INFO "mkiss: %s: crc mode smack forced.\n", 734 ax->dev->name); 735 break; 736 case 2: 737 ax->crcmode = CRC_MODE_FLEX; 738 printk(KERN_INFO "mkiss: %s: crc mode flexnet forced.\n", 739 ax->dev->name); 740 break; 741 case 1: 742 ax->crcmode = CRC_MODE_NONE; 743 printk(KERN_INFO "mkiss: %s: crc mode disabled.\n", 744 ax->dev->name); 745 break; 746 case 0: 747 default: 748 crc_force = 0; 749 printk(KERN_INFO "mkiss: %s: crc mode is auto.\n", 750 ax->dev->name); 751 ax->crcmode = CRC_MODE_SMACK_TEST; 752 } 753 ax->crcauto = (crc_force ? 0 : 1); 754 755 netif_start_queue(dev); 756 757 /* Done. We have linked the TTY line to a channel. */ 758 return 0; 759 760 out_free_buffers: 761 kfree(ax->rbuff); 762 kfree(ax->xbuff); 763 764 out_free_netdev: 765 free_netdev(dev); 766 767 out: 768 return err; 769 } 770 771 static void mkiss_close(struct tty_struct *tty) 772 { 773 struct mkiss *ax; 774 775 write_lock_irq(&disc_data_lock); 776 ax = tty->disc_data; 777 tty->disc_data = NULL; 778 write_unlock_irq(&disc_data_lock); 779 780 if (!ax) 781 return; 782 783 /* 784 * We have now ensured that nobody can start using ap from now on, but 785 * we have to wait for all existing users to finish. 786 */ 787 if (!refcount_dec_and_test(&ax->refcnt)) 788 wait_for_completion(&ax->dead); 789 /* 790 * Halt the transmit queue so that a new transmit cannot scribble 791 * on our buffers 792 */ 793 netif_stop_queue(ax->dev); 794 795 ax->tty = NULL; 796 797 unregister_netdev(ax->dev); 798 799 /* Free all AX25 frame buffers after unreg. */ 800 kfree(ax->rbuff); 801 kfree(ax->xbuff); 802 803 free_netdev(ax->dev); 804 } 805 806 /* Perform I/O control on an active ax25 channel. */ 807 static int mkiss_ioctl(struct tty_struct *tty, struct file *file, 808 unsigned int cmd, unsigned long arg) 809 { 810 struct mkiss *ax = mkiss_get(tty); 811 struct net_device *dev; 812 unsigned int tmp, err; 813 814 /* First make sure we're connected. */ 815 if (ax == NULL) 816 return -ENXIO; 817 dev = ax->dev; 818 819 switch (cmd) { 820 case SIOCGIFNAME: 821 err = copy_to_user((void __user *) arg, ax->dev->name, 822 strlen(ax->dev->name) + 1) ? -EFAULT : 0; 823 break; 824 825 case SIOCGIFENCAP: 826 err = put_user(4, (int __user *) arg); 827 break; 828 829 case SIOCSIFENCAP: 830 if (get_user(tmp, (int __user *) arg)) { 831 err = -EFAULT; 832 break; 833 } 834 835 ax->mode = tmp; 836 dev->addr_len = AX25_ADDR_LEN; 837 dev->hard_header_len = AX25_KISS_HEADER_LEN + 838 AX25_MAX_HEADER_LEN + 3; 839 dev->type = ARPHRD_AX25; 840 841 err = 0; 842 break; 843 844 case SIOCSIFHWADDR: { 845 char addr[AX25_ADDR_LEN]; 846 847 if (copy_from_user(&addr, 848 (void __user *) arg, AX25_ADDR_LEN)) { 849 err = -EFAULT; 850 break; 851 } 852 853 netif_tx_lock_bh(dev); 854 __dev_addr_set(dev, addr, AX25_ADDR_LEN); 855 netif_tx_unlock_bh(dev); 856 857 err = 0; 858 break; 859 } 860 default: 861 err = -ENOIOCTLCMD; 862 } 863 864 mkiss_put(ax); 865 866 return err; 867 } 868 869 /* 870 * Handle the 'receiver data ready' interrupt. 871 * This function is called by the 'tty_io' module in the kernel when 872 * a block of data has been received, which can now be decapsulated 873 * and sent on to the AX.25 layer for further processing. 874 */ 875 static void mkiss_receive_buf(struct tty_struct *tty, const unsigned char *cp, 876 const char *fp, int count) 877 { 878 struct mkiss *ax = mkiss_get(tty); 879 880 if (!ax) 881 return; 882 883 /* 884 * Argh! mtu change time! - costs us the packet part received 885 * at the change 886 */ 887 if (ax->mtu != ax->dev->mtu + 73) 888 ax_changedmtu(ax); 889 890 /* Read the characters out of the buffer */ 891 while (count--) { 892 if (fp != NULL && *fp++) { 893 if (!test_and_set_bit(AXF_ERROR, &ax->flags)) 894 ax->dev->stats.rx_errors++; 895 cp++; 896 continue; 897 } 898 899 kiss_unesc(ax, *cp++); 900 } 901 902 mkiss_put(ax); 903 tty_unthrottle(tty); 904 } 905 906 /* 907 * Called by the driver when there's room for more data. If we have 908 * more packets to send, we send them here. 909 */ 910 static void mkiss_write_wakeup(struct tty_struct *tty) 911 { 912 struct mkiss *ax = mkiss_get(tty); 913 int actual; 914 915 if (!ax) 916 return; 917 918 if (ax->xleft <= 0) { 919 /* Now serial buffer is almost free & we can start 920 * transmission of another packet 921 */ 922 clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); 923 924 netif_wake_queue(ax->dev); 925 goto out; 926 } 927 928 actual = tty->ops->write(tty, ax->xhead, ax->xleft); 929 ax->xleft -= actual; 930 ax->xhead += actual; 931 932 out: 933 mkiss_put(ax); 934 } 935 936 static struct tty_ldisc_ops ax_ldisc = { 937 .owner = THIS_MODULE, 938 .num = N_AX25, 939 .name = "mkiss", 940 .open = mkiss_open, 941 .close = mkiss_close, 942 .ioctl = mkiss_ioctl, 943 .receive_buf = mkiss_receive_buf, 944 .write_wakeup = mkiss_write_wakeup 945 }; 946 947 static const char banner[] __initconst = KERN_INFO \ 948 "mkiss: AX.25 Multikiss, Hans Albas PE1AYX\n"; 949 static const char msg_regfail[] __initconst = KERN_ERR \ 950 "mkiss: can't register line discipline (err = %d)\n"; 951 952 static int __init mkiss_init_driver(void) 953 { 954 int status; 955 956 printk(banner); 957 958 status = tty_register_ldisc(&ax_ldisc); 959 if (status != 0) 960 printk(msg_regfail, status); 961 962 return status; 963 } 964 965 static void __exit mkiss_exit_driver(void) 966 { 967 tty_unregister_ldisc(&ax_ldisc); 968 } 969 970 MODULE_AUTHOR("Ralf Baechle DL5RB <ralf@linux-mips.org>"); 971 MODULE_DESCRIPTION("KISS driver for AX.25 over TTYs"); 972 module_param(crc_force, int, 0); 973 MODULE_PARM_DESC(crc_force, "crc [0 = auto | 1 = none | 2 = flexnet | 3 = smack]"); 974 MODULE_LICENSE("GPL"); 975 MODULE_ALIAS_LDISC(N_AX25); 976 977 module_init(mkiss_init_driver); 978 module_exit(mkiss_exit_driver); 979