| 1 | /* |
| 2 | * PPP async serial channel driver for Linux. |
| 3 | * |
| 4 | * Copyright 1999 Paul Mackerras. |
| 5 | * |
| 6 | * This program is free software; you can redistribute it and/or |
| 7 | * modify it under the terms of the GNU General Public License |
| 8 | * as published by the Free Software Foundation; either version |
| 9 | * 2 of the License, or (at your option) any later version. |
| 10 | * |
| 11 | * This driver provides the encapsulation and framing for sending |
| 12 | * and receiving PPP frames over async serial lines. It relies on |
| 13 | * the generic PPP layer to give it frames to send and to process |
| 14 | * received frames. It implements the PPP line discipline. |
| 15 | * |
| 16 | * Part of the code in this driver was inspired by the old async-only |
| 17 | * PPP driver, written by Michael Callahan and Al Longyear, and |
| 18 | * subsequently hacked by Paul Mackerras. |
| 19 | */ |
| 20 | |
| 21 | #include <linux/module.h> |
| 22 | #include <linux/kernel.h> |
| 23 | #include <linux/skbuff.h> |
| 24 | #include <linux/tty.h> |
| 25 | #include <linux/netdevice.h> |
| 26 | #include <linux/poll.h> |
| 27 | #include <linux/crc-ccitt.h> |
| 28 | #include <linux/ppp_defs.h> |
| 29 | #include <linux/if_ppp.h> |
| 30 | #include <linux/ppp_channel.h> |
| 31 | #include <linux/spinlock.h> |
| 32 | #include <linux/init.h> |
| 33 | #include <linux/jiffies.h> |
| 34 | #include <asm/uaccess.h> |
| 35 | #include <asm/string.h> |
| 36 | |
| 37 | #define PPP_VERSION "2.4.2" |
| 38 | |
| 39 | #define OBUFSIZE 256 |
| 40 | |
| 41 | /* Structure for storing local state. */ |
| 42 | struct asyncppp { |
| 43 | struct tty_struct *tty; |
| 44 | unsigned int flags; |
| 45 | unsigned int state; |
| 46 | unsigned int rbits; |
| 47 | int mru; |
| 48 | spinlock_t xmit_lock; |
| 49 | spinlock_t recv_lock; |
| 50 | unsigned long xmit_flags; |
| 51 | u32 xaccm[8]; |
| 52 | u32 raccm; |
| 53 | unsigned int bytes_sent; |
| 54 | unsigned int bytes_rcvd; |
| 55 | |
| 56 | struct sk_buff *tpkt; |
| 57 | int tpkt_pos; |
| 58 | u16 tfcs; |
| 59 | unsigned char *optr; |
| 60 | unsigned char *olim; |
| 61 | unsigned long last_xmit; |
| 62 | |
| 63 | struct sk_buff *rpkt; |
| 64 | int lcp_fcs; |
| 65 | struct sk_buff_head rqueue; |
| 66 | |
| 67 | struct tasklet_struct tsk; |
| 68 | |
| 69 | atomic_t refcnt; |
| 70 | struct semaphore dead_sem; |
| 71 | struct ppp_channel chan; /* interface to generic ppp layer */ |
| 72 | unsigned char obuf[OBUFSIZE]; |
| 73 | }; |
| 74 | |
| 75 | /* Bit numbers in xmit_flags */ |
| 76 | #define XMIT_WAKEUP 0 |
| 77 | #define XMIT_FULL 1 |
| 78 | #define XMIT_BUSY 2 |
| 79 | |
| 80 | /* State bits */ |
| 81 | #define SC_TOSS 1 |
| 82 | #define SC_ESCAPE 2 |
| 83 | #define SC_PREV_ERROR 4 |
| 84 | |
| 85 | /* Bits in rbits */ |
| 86 | #define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP) |
| 87 | |
| 88 | static int flag_time = HZ; |
| 89 | module_param(flag_time, int, 0); |
| 90 | MODULE_PARM_DESC(flag_time, "ppp_async: interval between flagged packets (in clock ticks)"); |
| 91 | MODULE_LICENSE("GPL"); |
| 92 | MODULE_ALIAS_LDISC(N_PPP); |
| 93 | |
| 94 | /* |
| 95 | * Prototypes. |
| 96 | */ |
| 97 | static int ppp_async_encode(struct asyncppp *ap); |
| 98 | static int ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb); |
| 99 | static int ppp_async_push(struct asyncppp *ap); |
| 100 | static void ppp_async_flush_output(struct asyncppp *ap); |
| 101 | static void ppp_async_input(struct asyncppp *ap, const unsigned char *buf, |
| 102 | char *flags, int count); |
| 103 | static int ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, |
| 104 | unsigned long arg); |
| 105 | static void ppp_async_process(unsigned long arg); |
| 106 | |
| 107 | static void async_lcp_peek(struct asyncppp *ap, unsigned char *data, |
| 108 | int len, int inbound); |
| 109 | |
| 110 | static struct ppp_channel_ops async_ops = { |
| 111 | ppp_async_send, |
| 112 | ppp_async_ioctl |
| 113 | }; |
| 114 | |
| 115 | /* |
| 116 | * Routines implementing the PPP line discipline. |
| 117 | */ |
| 118 | |
| 119 | /* |
| 120 | * We have a potential race on dereferencing tty->disc_data, |
| 121 | * because the tty layer provides no locking at all - thus one |
| 122 | * cpu could be running ppp_asynctty_receive while another |
| 123 | * calls ppp_asynctty_close, which zeroes tty->disc_data and |
| 124 | * frees the memory that ppp_asynctty_receive is using. The best |
| 125 | * way to fix this is to use a rwlock in the tty struct, but for now |
| 126 | * we use a single global rwlock for all ttys in ppp line discipline. |
| 127 | * |
| 128 | * FIXME: this is no longer true. The _close path for the ldisc is |
| 129 | * now guaranteed to be sane. |
| 130 | */ |
| 131 | static DEFINE_RWLOCK(disc_data_lock); |
| 132 | |
| 133 | static struct asyncppp *ap_get(struct tty_struct *tty) |
| 134 | { |
| 135 | struct asyncppp *ap; |
| 136 | |
| 137 | read_lock(&disc_data_lock); |
| 138 | ap = tty->disc_data; |
| 139 | if (ap != NULL) |
| 140 | atomic_inc(&ap->refcnt); |
| 141 | read_unlock(&disc_data_lock); |
| 142 | return ap; |
| 143 | } |
| 144 | |
| 145 | static void ap_put(struct asyncppp *ap) |
| 146 | { |
| 147 | if (atomic_dec_and_test(&ap->refcnt)) |
| 148 | up(&ap->dead_sem); |
| 149 | } |
| 150 | |
| 151 | /* |
| 152 | * Called when a tty is put into PPP line discipline. Called in process |
| 153 | * context. |
| 154 | */ |
| 155 | static int |
| 156 | ppp_asynctty_open(struct tty_struct *tty) |
| 157 | { |
| 158 | struct asyncppp *ap; |
| 159 | int err; |
| 160 | int speed; |
| 161 | |
| 162 | if (tty->ops->write == NULL) |
| 163 | return -EOPNOTSUPP; |
| 164 | |
| 165 | err = -ENOMEM; |
| 166 | ap = kzalloc(sizeof(*ap), GFP_KERNEL); |
| 167 | if (!ap) |
| 168 | goto out; |
| 169 | |
| 170 | /* initialize the asyncppp structure */ |
| 171 | ap->tty = tty; |
| 172 | ap->mru = PPP_MRU; |
| 173 | spin_lock_init(&ap->xmit_lock); |
| 174 | spin_lock_init(&ap->recv_lock); |
| 175 | ap->xaccm[0] = ~0U; |
| 176 | ap->xaccm[3] = 0x60000000U; |
| 177 | ap->raccm = ~0U; |
| 178 | ap->optr = ap->obuf; |
| 179 | ap->olim = ap->obuf; |
| 180 | ap->lcp_fcs = -1; |
| 181 | |
| 182 | skb_queue_head_init(&ap->rqueue); |
| 183 | tasklet_init(&ap->tsk, ppp_async_process, (unsigned long) ap); |
| 184 | |
| 185 | atomic_set(&ap->refcnt, 1); |
| 186 | init_MUTEX_LOCKED(&ap->dead_sem); |
| 187 | |
| 188 | ap->chan.private = ap; |
| 189 | ap->chan.ops = &async_ops; |
| 190 | ap->chan.mtu = PPP_MRU; |
| 191 | speed = tty_get_baud_rate(tty); |
| 192 | ap->chan.speed = speed; |
| 193 | err = ppp_register_channel(&ap->chan); |
| 194 | if (err) |
| 195 | goto out_free; |
| 196 | |
| 197 | tty->disc_data = ap; |
| 198 | tty->receive_room = 65536; |
| 199 | return 0; |
| 200 | |
| 201 | out_free: |
| 202 | kfree(ap); |
| 203 | out: |
| 204 | return err; |
| 205 | } |
| 206 | |
| 207 | /* |
| 208 | * Called when the tty is put into another line discipline |
| 209 | * or it hangs up. We have to wait for any cpu currently |
| 210 | * executing in any of the other ppp_asynctty_* routines to |
| 211 | * finish before we can call ppp_unregister_channel and free |
| 212 | * the asyncppp struct. This routine must be called from |
| 213 | * process context, not interrupt or softirq context. |
| 214 | */ |
| 215 | static void |
| 216 | ppp_asynctty_close(struct tty_struct *tty) |
| 217 | { |
| 218 | struct asyncppp *ap; |
| 219 | |
| 220 | write_lock_irq(&disc_data_lock); |
| 221 | ap = tty->disc_data; |
| 222 | tty->disc_data = NULL; |
| 223 | write_unlock_irq(&disc_data_lock); |
| 224 | if (!ap) |
| 225 | return; |
| 226 | |
| 227 | /* |
| 228 | * We have now ensured that nobody can start using ap from now |
| 229 | * on, but we have to wait for all existing users to finish. |
| 230 | * Note that ppp_unregister_channel ensures that no calls to |
| 231 | * our channel ops (i.e. ppp_async_send/ioctl) are in progress |
| 232 | * by the time it returns. |
| 233 | */ |
| 234 | if (!atomic_dec_and_test(&ap->refcnt)) |
| 235 | down(&ap->dead_sem); |
| 236 | tasklet_kill(&ap->tsk); |
| 237 | |
| 238 | ppp_unregister_channel(&ap->chan); |
| 239 | kfree_skb(ap->rpkt); |
| 240 | skb_queue_purge(&ap->rqueue); |
| 241 | kfree_skb(ap->tpkt); |
| 242 | kfree(ap); |
| 243 | } |
| 244 | |
| 245 | /* |
| 246 | * Called on tty hangup in process context. |
| 247 | * |
| 248 | * Wait for I/O to driver to complete and unregister PPP channel. |
| 249 | * This is already done by the close routine, so just call that. |
| 250 | */ |
| 251 | static int ppp_asynctty_hangup(struct tty_struct *tty) |
| 252 | { |
| 253 | ppp_asynctty_close(tty); |
| 254 | return 0; |
| 255 | } |
| 256 | |
| 257 | /* |
| 258 | * Read does nothing - no data is ever available this way. |
| 259 | * Pppd reads and writes packets via /dev/ppp instead. |
| 260 | */ |
| 261 | static ssize_t |
| 262 | ppp_asynctty_read(struct tty_struct *tty, struct file *file, |
| 263 | unsigned char __user *buf, size_t count) |
| 264 | { |
| 265 | return -EAGAIN; |
| 266 | } |
| 267 | |
| 268 | /* |
| 269 | * Write on the tty does nothing, the packets all come in |
| 270 | * from the ppp generic stuff. |
| 271 | */ |
| 272 | static ssize_t |
| 273 | ppp_asynctty_write(struct tty_struct *tty, struct file *file, |
| 274 | const unsigned char *buf, size_t count) |
| 275 | { |
| 276 | return -EAGAIN; |
| 277 | } |
| 278 | |
| 279 | /* |
| 280 | * Called in process context only. May be re-entered by multiple |
| 281 | * ioctl calling threads. |
| 282 | */ |
| 283 | |
| 284 | static int |
| 285 | ppp_asynctty_ioctl(struct tty_struct *tty, struct file *file, |
| 286 | unsigned int cmd, unsigned long arg) |
| 287 | { |
| 288 | struct asyncppp *ap = ap_get(tty); |
| 289 | int err, val; |
| 290 | int __user *p = (int __user *)arg; |
| 291 | |
| 292 | if (!ap) |
| 293 | return -ENXIO; |
| 294 | err = -EFAULT; |
| 295 | switch (cmd) { |
| 296 | case PPPIOCGCHAN: |
| 297 | err = -EFAULT; |
| 298 | if (put_user(ppp_channel_index(&ap->chan), p)) |
| 299 | break; |
| 300 | err = 0; |
| 301 | break; |
| 302 | |
| 303 | case PPPIOCGUNIT: |
| 304 | err = -EFAULT; |
| 305 | if (put_user(ppp_unit_number(&ap->chan), p)) |
| 306 | break; |
| 307 | err = 0; |
| 308 | break; |
| 309 | |
| 310 | case TCFLSH: |
| 311 | /* flush our buffers and the serial port's buffer */ |
| 312 | if (arg == TCIOFLUSH || arg == TCOFLUSH) |
| 313 | ppp_async_flush_output(ap); |
| 314 | err = tty_perform_flush(tty, arg); |
| 315 | break; |
| 316 | |
| 317 | case FIONREAD: |
| 318 | val = 0; |
| 319 | if (put_user(val, p)) |
| 320 | break; |
| 321 | err = 0; |
| 322 | break; |
| 323 | |
| 324 | default: |
| 325 | /* Try the various mode ioctls */ |
| 326 | err = tty_mode_ioctl(tty, file, cmd, arg); |
| 327 | } |
| 328 | |
| 329 | ap_put(ap); |
| 330 | return err; |
| 331 | } |
| 332 | |
| 333 | /* No kernel lock - fine */ |
| 334 | static unsigned int |
| 335 | ppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait) |
| 336 | { |
| 337 | return 0; |
| 338 | } |
| 339 | |
| 340 | /* |
| 341 | * This can now be called from hard interrupt level as well |
| 342 | * as soft interrupt level or mainline. |
| 343 | */ |
| 344 | static void |
| 345 | ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf, |
| 346 | char *cflags, int count) |
| 347 | { |
| 348 | struct asyncppp *ap = ap_get(tty); |
| 349 | unsigned long flags; |
| 350 | |
| 351 | if (!ap) |
| 352 | return; |
| 353 | spin_lock_irqsave(&ap->recv_lock, flags); |
| 354 | ppp_async_input(ap, buf, cflags, count); |
| 355 | spin_unlock_irqrestore(&ap->recv_lock, flags); |
| 356 | if (!skb_queue_empty(&ap->rqueue)) |
| 357 | tasklet_schedule(&ap->tsk); |
| 358 | ap_put(ap); |
| 359 | tty_unthrottle(tty); |
| 360 | } |
| 361 | |
| 362 | static void |
| 363 | ppp_asynctty_wakeup(struct tty_struct *tty) |
| 364 | { |
| 365 | struct asyncppp *ap = ap_get(tty); |
| 366 | |
| 367 | clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
| 368 | if (!ap) |
| 369 | return; |
| 370 | set_bit(XMIT_WAKEUP, &ap->xmit_flags); |
| 371 | tasklet_schedule(&ap->tsk); |
| 372 | ap_put(ap); |
| 373 | } |
| 374 | |
| 375 | |
| 376 | static struct tty_ldisc_ops ppp_ldisc = { |
| 377 | .owner = THIS_MODULE, |
| 378 | .magic = TTY_LDISC_MAGIC, |
| 379 | .name = "ppp", |
| 380 | .open = ppp_asynctty_open, |
| 381 | .close = ppp_asynctty_close, |
| 382 | .hangup = ppp_asynctty_hangup, |
| 383 | .read = ppp_asynctty_read, |
| 384 | .write = ppp_asynctty_write, |
| 385 | .ioctl = ppp_asynctty_ioctl, |
| 386 | .poll = ppp_asynctty_poll, |
| 387 | .receive_buf = ppp_asynctty_receive, |
| 388 | .write_wakeup = ppp_asynctty_wakeup, |
| 389 | }; |
| 390 | |
| 391 | static int __init |
| 392 | ppp_async_init(void) |
| 393 | { |
| 394 | int err; |
| 395 | |
| 396 | err = tty_register_ldisc(N_PPP, &ppp_ldisc); |
| 397 | if (err != 0) |
| 398 | printk(KERN_ERR "PPP_async: error %d registering line disc.\n", |
| 399 | err); |
| 400 | return err; |
| 401 | } |
| 402 | |
| 403 | /* |
| 404 | * The following routines provide the PPP channel interface. |
| 405 | */ |
| 406 | static int |
| 407 | ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg) |
| 408 | { |
| 409 | struct asyncppp *ap = chan->private; |
| 410 | void __user *argp = (void __user *)arg; |
| 411 | int __user *p = argp; |
| 412 | int err, val; |
| 413 | u32 accm[8]; |
| 414 | |
| 415 | err = -EFAULT; |
| 416 | switch (cmd) { |
| 417 | case PPPIOCGFLAGS: |
| 418 | val = ap->flags | ap->rbits; |
| 419 | if (put_user(val, p)) |
| 420 | break; |
| 421 | err = 0; |
| 422 | break; |
| 423 | case PPPIOCSFLAGS: |
| 424 | if (get_user(val, p)) |
| 425 | break; |
| 426 | ap->flags = val & ~SC_RCV_BITS; |
| 427 | spin_lock_irq(&ap->recv_lock); |
| 428 | ap->rbits = val & SC_RCV_BITS; |
| 429 | spin_unlock_irq(&ap->recv_lock); |
| 430 | err = 0; |
| 431 | break; |
| 432 | |
| 433 | case PPPIOCGASYNCMAP: |
| 434 | if (put_user(ap->xaccm[0], (u32 __user *)argp)) |
| 435 | break; |
| 436 | err = 0; |
| 437 | break; |
| 438 | case PPPIOCSASYNCMAP: |
| 439 | if (get_user(ap->xaccm[0], (u32 __user *)argp)) |
| 440 | break; |
| 441 | err = 0; |
| 442 | break; |
| 443 | |
| 444 | case PPPIOCGRASYNCMAP: |
| 445 | if (put_user(ap->raccm, (u32 __user *)argp)) |
| 446 | break; |
| 447 | err = 0; |
| 448 | break; |
| 449 | case PPPIOCSRASYNCMAP: |
| 450 | if (get_user(ap->raccm, (u32 __user *)argp)) |
| 451 | break; |
| 452 | err = 0; |
| 453 | break; |
| 454 | |
| 455 | case PPPIOCGXASYNCMAP: |
| 456 | if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm))) |
| 457 | break; |
| 458 | err = 0; |
| 459 | break; |
| 460 | case PPPIOCSXASYNCMAP: |
| 461 | if (copy_from_user(accm, argp, sizeof(accm))) |
| 462 | break; |
| 463 | accm[2] &= ~0x40000000U; /* can't escape 0x5e */ |
| 464 | accm[3] |= 0x60000000U; /* must escape 0x7d, 0x7e */ |
| 465 | memcpy(ap->xaccm, accm, sizeof(ap->xaccm)); |
| 466 | err = 0; |
| 467 | break; |
| 468 | |
| 469 | case PPPIOCGMRU: |
| 470 | if (put_user(ap->mru, p)) |
| 471 | break; |
| 472 | err = 0; |
| 473 | break; |
| 474 | case PPPIOCSMRU: |
| 475 | if (get_user(val, p)) |
| 476 | break; |
| 477 | if (val < PPP_MRU) |
| 478 | val = PPP_MRU; |
| 479 | ap->mru = val; |
| 480 | err = 0; |
| 481 | break; |
| 482 | |
| 483 | default: |
| 484 | err = -ENOTTY; |
| 485 | } |
| 486 | |
| 487 | return err; |
| 488 | } |
| 489 | |
| 490 | /* |
| 491 | * This is called at softirq level to deliver received packets |
| 492 | * to the ppp_generic code, and to tell the ppp_generic code |
| 493 | * if we can accept more output now. |
| 494 | */ |
| 495 | static void ppp_async_process(unsigned long arg) |
| 496 | { |
| 497 | struct asyncppp *ap = (struct asyncppp *) arg; |
| 498 | struct sk_buff *skb; |
| 499 | |
| 500 | /* process received packets */ |
| 501 | while ((skb = skb_dequeue(&ap->rqueue)) != NULL) { |
| 502 | if (skb->cb[0]) |
| 503 | ppp_input_error(&ap->chan, 0); |
| 504 | ppp_input(&ap->chan, skb); |
| 505 | } |
| 506 | |
| 507 | /* try to push more stuff out */ |
| 508 | if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_async_push(ap)) |
| 509 | ppp_output_wakeup(&ap->chan); |
| 510 | } |
| 511 | |
| 512 | /* |
| 513 | * Procedures for encapsulation and framing. |
| 514 | */ |
| 515 | |
| 516 | /* |
| 517 | * Procedure to encode the data for async serial transmission. |
| 518 | * Does octet stuffing (escaping), puts the address/control bytes |
| 519 | * on if A/C compression is disabled, and does protocol compression. |
| 520 | * Assumes ap->tpkt != 0 on entry. |
| 521 | * Returns 1 if we finished the current frame, 0 otherwise. |
| 522 | */ |
| 523 | |
| 524 | #define PUT_BYTE(ap, buf, c, islcp) do { \ |
| 525 | if ((islcp && c < 0x20) || (ap->xaccm[c >> 5] & (1 << (c & 0x1f)))) {\ |
| 526 | *buf++ = PPP_ESCAPE; \ |
| 527 | *buf++ = c ^ 0x20; \ |
| 528 | } else \ |
| 529 | *buf++ = c; \ |
| 530 | } while (0) |
| 531 | |
| 532 | static int |
| 533 | ppp_async_encode(struct asyncppp *ap) |
| 534 | { |
| 535 | int fcs, i, count, c, proto; |
| 536 | unsigned char *buf, *buflim; |
| 537 | unsigned char *data; |
| 538 | int islcp; |
| 539 | |
| 540 | buf = ap->obuf; |
| 541 | ap->olim = buf; |
| 542 | ap->optr = buf; |
| 543 | i = ap->tpkt_pos; |
| 544 | data = ap->tpkt->data; |
| 545 | count = ap->tpkt->len; |
| 546 | fcs = ap->tfcs; |
| 547 | proto = (data[0] << 8) + data[1]; |
| 548 | |
| 549 | /* |
| 550 | * LCP packets with code values between 1 (configure-reqest) |
| 551 | * and 7 (code-reject) must be sent as though no options |
| 552 | * had been negotiated. |
| 553 | */ |
| 554 | islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7; |
| 555 | |
| 556 | if (i == 0) { |
| 557 | if (islcp) |
| 558 | async_lcp_peek(ap, data, count, 0); |
| 559 | |
| 560 | /* |
| 561 | * Start of a new packet - insert the leading FLAG |
| 562 | * character if necessary. |
| 563 | */ |
| 564 | if (islcp || flag_time == 0 |
| 565 | || time_after_eq(jiffies, ap->last_xmit + flag_time)) |
| 566 | *buf++ = PPP_FLAG; |
| 567 | ap->last_xmit = jiffies; |
| 568 | fcs = PPP_INITFCS; |
| 569 | |
| 570 | /* |
| 571 | * Put in the address/control bytes if necessary |
| 572 | */ |
| 573 | if ((ap->flags & SC_COMP_AC) == 0 || islcp) { |
| 574 | PUT_BYTE(ap, buf, 0xff, islcp); |
| 575 | fcs = PPP_FCS(fcs, 0xff); |
| 576 | PUT_BYTE(ap, buf, 0x03, islcp); |
| 577 | fcs = PPP_FCS(fcs, 0x03); |
| 578 | } |
| 579 | } |
| 580 | |
| 581 | /* |
| 582 | * Once we put in the last byte, we need to put in the FCS |
| 583 | * and closing flag, so make sure there is at least 7 bytes |
| 584 | * of free space in the output buffer. |
| 585 | */ |
| 586 | buflim = ap->obuf + OBUFSIZE - 6; |
| 587 | while (i < count && buf < buflim) { |
| 588 | c = data[i++]; |
| 589 | if (i == 1 && c == 0 && (ap->flags & SC_COMP_PROT)) |
| 590 | continue; /* compress protocol field */ |
| 591 | fcs = PPP_FCS(fcs, c); |
| 592 | PUT_BYTE(ap, buf, c, islcp); |
| 593 | } |
| 594 | |
| 595 | if (i < count) { |
| 596 | /* |
| 597 | * Remember where we are up to in this packet. |
| 598 | */ |
| 599 | ap->olim = buf; |
| 600 | ap->tpkt_pos = i; |
| 601 | ap->tfcs = fcs; |
| 602 | return 0; |
| 603 | } |
| 604 | |
| 605 | /* |
| 606 | * We have finished the packet. Add the FCS and flag. |
| 607 | */ |
| 608 | fcs = ~fcs; |
| 609 | c = fcs & 0xff; |
| 610 | PUT_BYTE(ap, buf, c, islcp); |
| 611 | c = (fcs >> 8) & 0xff; |
| 612 | PUT_BYTE(ap, buf, c, islcp); |
| 613 | *buf++ = PPP_FLAG; |
| 614 | ap->olim = buf; |
| 615 | |
| 616 | kfree_skb(ap->tpkt); |
| 617 | ap->tpkt = NULL; |
| 618 | return 1; |
| 619 | } |
| 620 | |
| 621 | /* |
| 622 | * Transmit-side routines. |
| 623 | */ |
| 624 | |
| 625 | /* |
| 626 | * Send a packet to the peer over an async tty line. |
| 627 | * Returns 1 iff the packet was accepted. |
| 628 | * If the packet was not accepted, we will call ppp_output_wakeup |
| 629 | * at some later time. |
| 630 | */ |
| 631 | static int |
| 632 | ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb) |
| 633 | { |
| 634 | struct asyncppp *ap = chan->private; |
| 635 | |
| 636 | ppp_async_push(ap); |
| 637 | |
| 638 | if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags)) |
| 639 | return 0; /* already full */ |
| 640 | ap->tpkt = skb; |
| 641 | ap->tpkt_pos = 0; |
| 642 | |
| 643 | ppp_async_push(ap); |
| 644 | return 1; |
| 645 | } |
| 646 | |
| 647 | /* |
| 648 | * Push as much data as possible out to the tty. |
| 649 | */ |
| 650 | static int |
| 651 | ppp_async_push(struct asyncppp *ap) |
| 652 | { |
| 653 | int avail, sent, done = 0; |
| 654 | struct tty_struct *tty = ap->tty; |
| 655 | int tty_stuffed = 0; |
| 656 | |
| 657 | /* |
| 658 | * We can get called recursively here if the tty write |
| 659 | * function calls our wakeup function. This can happen |
| 660 | * for example on a pty with both the master and slave |
| 661 | * set to PPP line discipline. |
| 662 | * We use the XMIT_BUSY bit to detect this and get out, |
| 663 | * leaving the XMIT_WAKEUP bit set to tell the other |
| 664 | * instance that it may now be able to write more now. |
| 665 | */ |
| 666 | if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags)) |
| 667 | return 0; |
| 668 | spin_lock_bh(&ap->xmit_lock); |
| 669 | for (;;) { |
| 670 | if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags)) |
| 671 | tty_stuffed = 0; |
| 672 | if (!tty_stuffed && ap->optr < ap->olim) { |
| 673 | avail = ap->olim - ap->optr; |
| 674 | set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); |
| 675 | sent = tty->ops->write(tty, ap->optr, avail); |
| 676 | if (sent < 0) |
| 677 | goto flush; /* error, e.g. loss of CD */ |
| 678 | ap->optr += sent; |
| 679 | if (sent < avail) |
| 680 | tty_stuffed = 1; |
| 681 | continue; |
| 682 | } |
| 683 | if (ap->optr >= ap->olim && ap->tpkt) { |
| 684 | if (ppp_async_encode(ap)) { |
| 685 | /* finished processing ap->tpkt */ |
| 686 | clear_bit(XMIT_FULL, &ap->xmit_flags); |
| 687 | done = 1; |
| 688 | } |
| 689 | continue; |
| 690 | } |
| 691 | /* |
| 692 | * We haven't made any progress this time around. |
| 693 | * Clear XMIT_BUSY to let other callers in, but |
| 694 | * after doing so we have to check if anyone set |
| 695 | * XMIT_WAKEUP since we last checked it. If they |
| 696 | * did, we should try again to set XMIT_BUSY and go |
| 697 | * around again in case XMIT_BUSY was still set when |
| 698 | * the other caller tried. |
| 699 | */ |
| 700 | clear_bit(XMIT_BUSY, &ap->xmit_flags); |
| 701 | /* any more work to do? if not, exit the loop */ |
| 702 | if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags) |
| 703 | || (!tty_stuffed && ap->tpkt))) |
| 704 | break; |
| 705 | /* more work to do, see if we can do it now */ |
| 706 | if (test_and_set_bit(XMIT_BUSY, &ap->xmit_flags)) |
| 707 | break; |
| 708 | } |
| 709 | spin_unlock_bh(&ap->xmit_lock); |
| 710 | return done; |
| 711 | |
| 712 | flush: |
| 713 | clear_bit(XMIT_BUSY, &ap->xmit_flags); |
| 714 | if (ap->tpkt) { |
| 715 | kfree_skb(ap->tpkt); |
| 716 | ap->tpkt = NULL; |
| 717 | clear_bit(XMIT_FULL, &ap->xmit_flags); |
| 718 | done = 1; |
| 719 | } |
| 720 | ap->optr = ap->olim; |
| 721 | spin_unlock_bh(&ap->xmit_lock); |
| 722 | return done; |
| 723 | } |
| 724 | |
| 725 | /* |
| 726 | * Flush output from our internal buffers. |
| 727 | * Called for the TCFLSH ioctl. Can be entered in parallel |
| 728 | * but this is covered by the xmit_lock. |
| 729 | */ |
| 730 | static void |
| 731 | ppp_async_flush_output(struct asyncppp *ap) |
| 732 | { |
| 733 | int done = 0; |
| 734 | |
| 735 | spin_lock_bh(&ap->xmit_lock); |
| 736 | ap->optr = ap->olim; |
| 737 | if (ap->tpkt != NULL) { |
| 738 | kfree_skb(ap->tpkt); |
| 739 | ap->tpkt = NULL; |
| 740 | clear_bit(XMIT_FULL, &ap->xmit_flags); |
| 741 | done = 1; |
| 742 | } |
| 743 | spin_unlock_bh(&ap->xmit_lock); |
| 744 | if (done) |
| 745 | ppp_output_wakeup(&ap->chan); |
| 746 | } |
| 747 | |
| 748 | /* |
| 749 | * Receive-side routines. |
| 750 | */ |
| 751 | |
| 752 | /* see how many ordinary chars there are at the start of buf */ |
| 753 | static inline int |
| 754 | scan_ordinary(struct asyncppp *ap, const unsigned char *buf, int count) |
| 755 | { |
| 756 | int i, c; |
| 757 | |
| 758 | for (i = 0; i < count; ++i) { |
| 759 | c = buf[i]; |
| 760 | if (c == PPP_ESCAPE || c == PPP_FLAG |
| 761 | || (c < 0x20 && (ap->raccm & (1 << c)) != 0)) |
| 762 | break; |
| 763 | } |
| 764 | return i; |
| 765 | } |
| 766 | |
| 767 | /* called when a flag is seen - do end-of-packet processing */ |
| 768 | static void |
| 769 | process_input_packet(struct asyncppp *ap) |
| 770 | { |
| 771 | struct sk_buff *skb; |
| 772 | unsigned char *p; |
| 773 | unsigned int len, fcs, proto; |
| 774 | |
| 775 | skb = ap->rpkt; |
| 776 | if (ap->state & (SC_TOSS | SC_ESCAPE)) |
| 777 | goto err; |
| 778 | |
| 779 | if (skb == NULL) |
| 780 | return; /* 0-length packet */ |
| 781 | |
| 782 | /* check the FCS */ |
| 783 | p = skb->data; |
| 784 | len = skb->len; |
| 785 | if (len < 3) |
| 786 | goto err; /* too short */ |
| 787 | fcs = PPP_INITFCS; |
| 788 | for (; len > 0; --len) |
| 789 | fcs = PPP_FCS(fcs, *p++); |
| 790 | if (fcs != PPP_GOODFCS) |
| 791 | goto err; /* bad FCS */ |
| 792 | skb_trim(skb, skb->len - 2); |
| 793 | |
| 794 | /* check for address/control and protocol compression */ |
| 795 | p = skb->data; |
| 796 | if (p[0] == PPP_ALLSTATIONS) { |
| 797 | /* chop off address/control */ |
| 798 | if (p[1] != PPP_UI || skb->len < 3) |
| 799 | goto err; |
| 800 | p = skb_pull(skb, 2); |
| 801 | } |
| 802 | proto = p[0]; |
| 803 | if (proto & 1) { |
| 804 | /* protocol is compressed */ |
| 805 | skb_push(skb, 1)[0] = 0; |
| 806 | } else { |
| 807 | if (skb->len < 2) |
| 808 | goto err; |
| 809 | proto = (proto << 8) + p[1]; |
| 810 | if (proto == PPP_LCP) |
| 811 | async_lcp_peek(ap, p, skb->len, 1); |
| 812 | } |
| 813 | |
| 814 | /* queue the frame to be processed */ |
| 815 | skb->cb[0] = ap->state; |
| 816 | skb_queue_tail(&ap->rqueue, skb); |
| 817 | ap->rpkt = NULL; |
| 818 | ap->state = 0; |
| 819 | return; |
| 820 | |
| 821 | err: |
| 822 | /* frame had an error, remember that, reset SC_TOSS & SC_ESCAPE */ |
| 823 | ap->state = SC_PREV_ERROR; |
| 824 | if (skb) { |
| 825 | /* make skb appear as freshly allocated */ |
| 826 | skb_trim(skb, 0); |
| 827 | skb_reserve(skb, - skb_headroom(skb)); |
| 828 | } |
| 829 | } |
| 830 | |
| 831 | /* Called when the tty driver has data for us. Runs parallel with the |
| 832 | other ldisc functions but will not be re-entered */ |
| 833 | |
| 834 | static void |
| 835 | ppp_async_input(struct asyncppp *ap, const unsigned char *buf, |
| 836 | char *flags, int count) |
| 837 | { |
| 838 | struct sk_buff *skb; |
| 839 | int c, i, j, n, s, f; |
| 840 | unsigned char *sp; |
| 841 | |
| 842 | /* update bits used for 8-bit cleanness detection */ |
| 843 | if (~ap->rbits & SC_RCV_BITS) { |
| 844 | s = 0; |
| 845 | for (i = 0; i < count; ++i) { |
| 846 | c = buf[i]; |
| 847 | if (flags && flags[i] != 0) |
| 848 | continue; |
| 849 | s |= (c & 0x80)? SC_RCV_B7_1: SC_RCV_B7_0; |
| 850 | c = ((c >> 4) ^ c) & 0xf; |
| 851 | s |= (0x6996 & (1 << c))? SC_RCV_ODDP: SC_RCV_EVNP; |
| 852 | } |
| 853 | ap->rbits |= s; |
| 854 | } |
| 855 | |
| 856 | while (count > 0) { |
| 857 | /* scan through and see how many chars we can do in bulk */ |
| 858 | if ((ap->state & SC_ESCAPE) && buf[0] == PPP_ESCAPE) |
| 859 | n = 1; |
| 860 | else |
| 861 | n = scan_ordinary(ap, buf, count); |
| 862 | |
| 863 | f = 0; |
| 864 | if (flags && (ap->state & SC_TOSS) == 0) { |
| 865 | /* check the flags to see if any char had an error */ |
| 866 | for (j = 0; j < n; ++j) |
| 867 | if ((f = flags[j]) != 0) |
| 868 | break; |
| 869 | } |
| 870 | if (f != 0) { |
| 871 | /* start tossing */ |
| 872 | ap->state |= SC_TOSS; |
| 873 | |
| 874 | } else if (n > 0 && (ap->state & SC_TOSS) == 0) { |
| 875 | /* stuff the chars in the skb */ |
| 876 | skb = ap->rpkt; |
| 877 | if (!skb) { |
| 878 | skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2); |
| 879 | if (!skb) |
| 880 | goto nomem; |
| 881 | ap->rpkt = skb; |
| 882 | } |
| 883 | if (skb->len == 0) { |
| 884 | /* Try to get the payload 4-byte aligned. |
| 885 | * This should match the |
| 886 | * PPP_ALLSTATIONS/PPP_UI/compressed tests in |
| 887 | * process_input_packet, but we do not have |
| 888 | * enough chars here to test buf[1] and buf[2]. |
| 889 | */ |
| 890 | if (buf[0] != PPP_ALLSTATIONS) |
| 891 | skb_reserve(skb, 2 + (buf[0] & 1)); |
| 892 | } |
| 893 | if (n > skb_tailroom(skb)) { |
| 894 | /* packet overflowed MRU */ |
| 895 | ap->state |= SC_TOSS; |
| 896 | } else { |
| 897 | sp = skb_put(skb, n); |
| 898 | memcpy(sp, buf, n); |
| 899 | if (ap->state & SC_ESCAPE) { |
| 900 | sp[0] ^= 0x20; |
| 901 | ap->state &= ~SC_ESCAPE; |
| 902 | } |
| 903 | } |
| 904 | } |
| 905 | |
| 906 | if (n >= count) |
| 907 | break; |
| 908 | |
| 909 | c = buf[n]; |
| 910 | if (flags != NULL && flags[n] != 0) { |
| 911 | ap->state |= SC_TOSS; |
| 912 | } else if (c == PPP_FLAG) { |
| 913 | process_input_packet(ap); |
| 914 | } else if (c == PPP_ESCAPE) { |
| 915 | ap->state |= SC_ESCAPE; |
| 916 | } else if (I_IXON(ap->tty)) { |
| 917 | if (c == START_CHAR(ap->tty)) |
| 918 | start_tty(ap->tty); |
| 919 | else if (c == STOP_CHAR(ap->tty)) |
| 920 | stop_tty(ap->tty); |
| 921 | } |
| 922 | /* otherwise it's a char in the recv ACCM */ |
| 923 | ++n; |
| 924 | |
| 925 | buf += n; |
| 926 | if (flags) |
| 927 | flags += n; |
| 928 | count -= n; |
| 929 | } |
| 930 | return; |
| 931 | |
| 932 | nomem: |
| 933 | printk(KERN_ERR "PPPasync: no memory (input pkt)\n"); |
| 934 | ap->state |= SC_TOSS; |
| 935 | } |
| 936 | |
| 937 | /* |
| 938 | * We look at LCP frames going past so that we can notice |
| 939 | * and react to the LCP configure-ack from the peer. |
| 940 | * In the situation where the peer has been sent a configure-ack |
| 941 | * already, LCP is up once it has sent its configure-ack |
| 942 | * so the immediately following packet can be sent with the |
| 943 | * configured LCP options. This allows us to process the following |
| 944 | * packet correctly without pppd needing to respond quickly. |
| 945 | * |
| 946 | * We only respond to the received configure-ack if we have just |
| 947 | * sent a configure-request, and the configure-ack contains the |
| 948 | * same data (this is checked using a 16-bit crc of the data). |
| 949 | */ |
| 950 | #define CONFREQ 1 /* LCP code field values */ |
| 951 | #define CONFACK 2 |
| 952 | #define LCP_MRU 1 /* LCP option numbers */ |
| 953 | #define LCP_ASYNCMAP 2 |
| 954 | |
| 955 | static void async_lcp_peek(struct asyncppp *ap, unsigned char *data, |
| 956 | int len, int inbound) |
| 957 | { |
| 958 | int dlen, fcs, i, code; |
| 959 | u32 val; |
| 960 | |
| 961 | data += 2; /* skip protocol bytes */ |
| 962 | len -= 2; |
| 963 | if (len < 4) /* 4 = code, ID, length */ |
| 964 | return; |
| 965 | code = data[0]; |
| 966 | if (code != CONFACK && code != CONFREQ) |
| 967 | return; |
| 968 | dlen = (data[2] << 8) + data[3]; |
| 969 | if (len < dlen) |
| 970 | return; /* packet got truncated or length is bogus */ |
| 971 | |
| 972 | if (code == (inbound? CONFACK: CONFREQ)) { |
| 973 | /* |
| 974 | * sent confreq or received confack: |
| 975 | * calculate the crc of the data from the ID field on. |
| 976 | */ |
| 977 | fcs = PPP_INITFCS; |
| 978 | for (i = 1; i < dlen; ++i) |
| 979 | fcs = PPP_FCS(fcs, data[i]); |
| 980 | |
| 981 | if (!inbound) { |
| 982 | /* outbound confreq - remember the crc for later */ |
| 983 | ap->lcp_fcs = fcs; |
| 984 | return; |
| 985 | } |
| 986 | |
| 987 | /* received confack, check the crc */ |
| 988 | fcs ^= ap->lcp_fcs; |
| 989 | ap->lcp_fcs = -1; |
| 990 | if (fcs != 0) |
| 991 | return; |
| 992 | } else if (inbound) |
| 993 | return; /* not interested in received confreq */ |
| 994 | |
| 995 | /* process the options in the confack */ |
| 996 | data += 4; |
| 997 | dlen -= 4; |
| 998 | /* data[0] is code, data[1] is length */ |
| 999 | while (dlen >= 2 && dlen >= data[1] && data[1] >= 2) { |
| 1000 | switch (data[0]) { |
| 1001 | case LCP_MRU: |
| 1002 | val = (data[2] << 8) + data[3]; |
| 1003 | if (inbound) |
| 1004 | ap->mru = val; |
| 1005 | else |
| 1006 | ap->chan.mtu = val; |
| 1007 | break; |
| 1008 | case LCP_ASYNCMAP: |
| 1009 | val = (data[2] << 24) + (data[3] << 16) |
| 1010 | + (data[4] << 8) + data[5]; |
| 1011 | if (inbound) |
| 1012 | ap->raccm = val; |
| 1013 | else |
| 1014 | ap->xaccm[0] = val; |
| 1015 | break; |
| 1016 | } |
| 1017 | dlen -= data[1]; |
| 1018 | data += data[1]; |
| 1019 | } |
| 1020 | } |
| 1021 | |
| 1022 | static void __exit ppp_async_cleanup(void) |
| 1023 | { |
| 1024 | if (tty_unregister_ldisc(N_PPP) != 0) |
| 1025 | printk(KERN_ERR "failed to unregister PPP line discipline\n"); |
| 1026 | } |
| 1027 | |
| 1028 | module_init(ppp_async_init); |
| 1029 | module_exit(ppp_async_cleanup); |