1/* 2 * ppp_deflate.c - interface the zlib procedures for Deflate compression 3 * and decompression (as used by gzip) to the PPP code. 4 * 5 * Copyright 1994-1998 Paul Mackerras. 6 * 7 * This program is free software; you can redistribute it and/or 8 * modify it under the terms of the GNU General Public License 9 * version 2 as published by the Free Software Foundation. 10 */ 11 12#include <linux/module.h> 13#include <linux/slab.h> 14#include <linux/vmalloc.h> 15#include <linux/init.h> 16#include <linux/string.h> 17 18#include <linux/ppp_defs.h> 19#include <linux/ppp-comp.h> 20 21#include <linux/zlib.h> 22#include <asm/unaligned.h> 23 24/* 25 * State for a Deflate (de)compressor. 26 */ 27struct ppp_deflate_state { 28 int seqno; 29 int w_size; 30 int unit; 31 int mru; 32 int debug; 33 z_stream strm; 34 struct compstat stats; 35}; 36 37#define DEFLATE_OVHD 2 /* Deflate overhead/packet */ 38 39static void *z_comp_alloc(unsigned char *options, int opt_len); 40static void *z_decomp_alloc(unsigned char *options, int opt_len); 41static void z_comp_free(void *state); 42static void z_decomp_free(void *state); 43static int z_comp_init(void *state, unsigned char *options, 44 int opt_len, 45 int unit, int hdrlen, int debug); 46static int z_decomp_init(void *state, unsigned char *options, 47 int opt_len, 48 int unit, int hdrlen, int mru, int debug); 49static int z_compress(void *state, unsigned char *rptr, 50 unsigned char *obuf, 51 int isize, int osize); 52static void z_incomp(void *state, unsigned char *ibuf, int icnt); 53static int z_decompress(void *state, unsigned char *ibuf, 54 int isize, unsigned char *obuf, int osize); 55static void z_comp_reset(void *state); 56static void z_decomp_reset(void *state); 57static void z_comp_stats(void *state, struct compstat *stats); 58 59/** 60 * z_comp_free - free the memory used by a compressor 61 * @arg: pointer to the private state for the compressor. 62 */ 63static void z_comp_free(void *arg) 64{ 65 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg; 66 67 if (state) { 68 zlib_deflateEnd(&state->strm); 69 vfree(state->strm.workspace); 70 kfree(state); 71 } 72} 73 74/** 75 * z_comp_alloc - allocate space for a compressor. 76 * @options: pointer to CCP option data 77 * @opt_len: length of the CCP option at @options. 78 * 79 * The @options pointer points to the a buffer containing the 80 * CCP option data for the compression being negotiated. It is 81 * formatted according to RFC1979, and describes the window 82 * size that the peer is requesting that we use in compressing 83 * data to be sent to it. 84 * 85 * Returns the pointer to the private state for the compressor, 86 * or NULL if we could not allocate enough memory. 87 */ 88static void *z_comp_alloc(unsigned char *options, int opt_len) 89{ 90 struct ppp_deflate_state *state; 91 int w_size; 92 93 if (opt_len != CILEN_DEFLATE || 94 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) || 95 options[1] != CILEN_DEFLATE || 96 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL || 97 options[3] != DEFLATE_CHK_SEQUENCE) 98 return NULL; 99 w_size = DEFLATE_SIZE(options[2]); 100 if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE) 101 return NULL; 102 103 state = kzalloc(sizeof(*state), 104 GFP_KERNEL); 105 if (state == NULL) 106 return NULL; 107 108 state->strm.next_in = NULL; 109 state->w_size = w_size; 110 state->strm.workspace = vmalloc(zlib_deflate_workspacesize(-w_size, 8)); 111 if (state->strm.workspace == NULL) 112 goto out_free; 113 114 if (zlib_deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION, 115 DEFLATE_METHOD_VAL, -w_size, 8, Z_DEFAULT_STRATEGY) 116 != Z_OK) 117 goto out_free; 118 return (void *) state; 119 120out_free: 121 z_comp_free(state); 122 return NULL; 123} 124 125/** 126 * z_comp_init - initialize a previously-allocated compressor. 127 * @arg: pointer to the private state for the compressor 128 * @options: pointer to the CCP option data describing the 129 * compression that was negotiated with the peer 130 * @opt_len: length of the CCP option data at @options 131 * @unit: PPP unit number for diagnostic messages 132 * @hdrlen: ignored (present for backwards compatibility) 133 * @debug: debug flag; if non-zero, debug messages are printed. 134 * 135 * The CCP options described by @options must match the options 136 * specified when the compressor was allocated. The compressor 137 * history is reset. Returns 0 for failure (CCP options don't 138 * match) or 1 for success. 139 */ 140static int z_comp_init(void *arg, unsigned char *options, int opt_len, 141 int unit, int hdrlen, int debug) 142{ 143 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg; 144 145 if (opt_len < CILEN_DEFLATE || 146 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) || 147 options[1] != CILEN_DEFLATE || 148 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL || 149 DEFLATE_SIZE(options[2]) != state->w_size || 150 options[3] != DEFLATE_CHK_SEQUENCE) 151 return 0; 152 153 state->seqno = 0; 154 state->unit = unit; 155 state->debug = debug; 156 157 zlib_deflateReset(&state->strm); 158 159 return 1; 160} 161 162/** 163 * z_comp_reset - reset a previously-allocated compressor. 164 * @arg: pointer to private state for the compressor. 165 * 166 * This clears the history for the compressor and makes it 167 * ready to start emitting a new compressed stream. 168 */ 169static void z_comp_reset(void *arg) 170{ 171 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg; 172 173 state->seqno = 0; 174 zlib_deflateReset(&state->strm); 175} 176 177/** 178 * z_compress - compress a PPP packet with Deflate compression. 179 * @arg: pointer to private state for the compressor 180 * @rptr: uncompressed packet (input) 181 * @obuf: compressed packet (output) 182 * @isize: size of uncompressed packet 183 * @osize: space available at @obuf 184 * 185 * Returns the length of the compressed packet, or 0 if the 186 * packet is incompressible. 187 */ 188static int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf, 189 int isize, int osize) 190{ 191 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg; 192 int r, proto, off, olen, oavail; 193 unsigned char *wptr; 194 195 /* 196 * Check that the protocol is in the range we handle. 197 */ 198 proto = PPP_PROTOCOL(rptr); 199 if (proto > 0x3fff || proto == 0xfd || proto == 0xfb) 200 return 0; 201 202 /* Don't generate compressed packets which are larger than 203 the uncompressed packet. */ 204 if (osize > isize) 205 osize = isize; 206 207 wptr = obuf; 208 209 /* 210 * Copy over the PPP header and store the 2-byte sequence number. 211 */ 212 wptr[0] = PPP_ADDRESS(rptr); 213 wptr[1] = PPP_CONTROL(rptr); 214 put_unaligned_be16(PPP_COMP, wptr + 2); 215 wptr += PPP_HDRLEN; 216 put_unaligned_be16(state->seqno, wptr); 217 wptr += DEFLATE_OVHD; 218 olen = PPP_HDRLEN + DEFLATE_OVHD; 219 state->strm.next_out = wptr; 220 state->strm.avail_out = oavail = osize - olen; 221 ++state->seqno; 222 223 off = (proto > 0xff) ? 2 : 3; /* skip 1st proto byte if 0 */ 224 rptr += off; 225 state->strm.next_in = rptr; 226 state->strm.avail_in = (isize - off); 227 228 for (;;) { 229 r = zlib_deflate(&state->strm, Z_PACKET_FLUSH); 230 if (r != Z_OK) { 231 if (state->debug) 232 printk(KERN_ERR 233 "z_compress: deflate returned %d\n", r); 234 break; 235 } 236 if (state->strm.avail_out == 0) { 237 olen += oavail; 238 state->strm.next_out = NULL; 239 state->strm.avail_out = oavail = 1000000; 240 } else { 241 break; /* all done */ 242 } 243 } 244 olen += oavail - state->strm.avail_out; 245 246 /* 247 * See if we managed to reduce the size of the packet. 248 */ 249 if (olen < isize) { 250 state->stats.comp_bytes += olen; 251 state->stats.comp_packets++; 252 } else { 253 state->stats.inc_bytes += isize; 254 state->stats.inc_packets++; 255 olen = 0; 256 } 257 state->stats.unc_bytes += isize; 258 state->stats.unc_packets++; 259 260 return olen; 261} 262 263/** 264 * z_comp_stats - return compression statistics for a compressor 265 * or decompressor. 266 * @arg: pointer to private space for the (de)compressor 267 * @stats: pointer to a struct compstat to receive the result. 268 */ 269static void z_comp_stats(void *arg, struct compstat *stats) 270{ 271 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg; 272 273 *stats = state->stats; 274} 275 276/** 277 * z_decomp_free - Free the memory used by a decompressor. 278 * @arg: pointer to private space for the decompressor. 279 */ 280static void z_decomp_free(void *arg) 281{ 282 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg; 283 284 if (state) { 285 zlib_inflateEnd(&state->strm); 286 vfree(state->strm.workspace); 287 kfree(state); 288 } 289} 290 291/** 292 * z_decomp_alloc - allocate space for a decompressor. 293 * @options: pointer to CCP option data 294 * @opt_len: length of the CCP option at @options. 295 * 296 * The @options pointer points to the a buffer containing the 297 * CCP option data for the compression being negotiated. It is 298 * formatted according to RFC1979, and describes the window 299 * size that we are requesting the peer to use in compressing 300 * data to be sent to us. 301 * 302 * Returns the pointer to the private state for the decompressor, 303 * or NULL if we could not allocate enough memory. 304 */ 305static void *z_decomp_alloc(unsigned char *options, int opt_len) 306{ 307 struct ppp_deflate_state *state; 308 int w_size; 309 310 if (opt_len != CILEN_DEFLATE || 311 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) || 312 options[1] != CILEN_DEFLATE || 313 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL || 314 options[3] != DEFLATE_CHK_SEQUENCE) 315 return NULL; 316 w_size = DEFLATE_SIZE(options[2]); 317 if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE) 318 return NULL; 319 320 state = kzalloc(sizeof(*state), GFP_KERNEL); 321 if (state == NULL) 322 return NULL; 323 324 state->w_size = w_size; 325 state->strm.next_out = NULL; 326 state->strm.workspace = vmalloc(zlib_inflate_workspacesize()); 327 if (state->strm.workspace == NULL) 328 goto out_free; 329 330 if (zlib_inflateInit2(&state->strm, -w_size) != Z_OK) 331 goto out_free; 332 return (void *) state; 333 334out_free: 335 z_decomp_free(state); 336 return NULL; 337} 338 339/** 340 * z_decomp_init - initialize a previously-allocated decompressor. 341 * @arg: pointer to the private state for the decompressor 342 * @options: pointer to the CCP option data describing the 343 * compression that was negotiated with the peer 344 * @opt_len: length of the CCP option data at @options 345 * @unit: PPP unit number for diagnostic messages 346 * @hdrlen: ignored (present for backwards compatibility) 347 * @mru: maximum length of decompressed packets 348 * @debug: debug flag; if non-zero, debug messages are printed. 349 * 350 * The CCP options described by @options must match the options 351 * specified when the decompressor was allocated. The decompressor 352 * history is reset. Returns 0 for failure (CCP options don't 353 * match) or 1 for success. 354 */ 355static int z_decomp_init(void *arg, unsigned char *options, int opt_len, 356 int unit, int hdrlen, int mru, int debug) 357{ 358 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg; 359 360 if (opt_len < CILEN_DEFLATE || 361 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) || 362 options[1] != CILEN_DEFLATE || 363 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL || 364 DEFLATE_SIZE(options[2]) != state->w_size || 365 options[3] != DEFLATE_CHK_SEQUENCE) 366 return 0; 367 368 state->seqno = 0; 369 state->unit = unit; 370 state->debug = debug; 371 state->mru = mru; 372 373 zlib_inflateReset(&state->strm); 374 375 return 1; 376} 377 378/** 379 * z_decomp_reset - reset a previously-allocated decompressor. 380 * @arg: pointer to private state for the decompressor. 381 * 382 * This clears the history for the decompressor and makes it 383 * ready to receive a new compressed stream. 384 */ 385static void z_decomp_reset(void *arg) 386{ 387 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg; 388 389 state->seqno = 0; 390 zlib_inflateReset(&state->strm); 391} 392 393/** 394 * z_decompress - decompress a Deflate-compressed packet. 395 * @arg: pointer to private state for the decompressor 396 * @ibuf: pointer to input (compressed) packet data 397 * @isize: length of input packet 398 * @obuf: pointer to space for output (decompressed) packet 399 * @osize: amount of space available at @obuf 400 * 401 * Because of patent problems, we return DECOMP_ERROR for errors 402 * found by inspecting the input data and for system problems, but 403 * DECOMP_FATALERROR for any errors which could possibly be said to 404 * be being detected "after" decompression. For DECOMP_ERROR, 405 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be 406 * infringing a patent of Motorola's if we do, so we take CCP down 407 * instead. 408 * 409 * Given that the frame has the correct sequence number and a good FCS, 410 * errors such as invalid codes in the input most likely indicate a 411 * bug, so we return DECOMP_FATALERROR for them in order to turn off 412 * compression, even though they are detected by inspecting the input. 413 */ 414static int z_decompress(void *arg, unsigned char *ibuf, int isize, 415 unsigned char *obuf, int osize) 416{ 417 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg; 418 int olen, seq, r; 419 int decode_proto, overflow; 420 unsigned char overflow_buf[1]; 421 422 if (isize <= PPP_HDRLEN + DEFLATE_OVHD) { 423 if (state->debug) 424 printk(KERN_DEBUG "z_decompress%d: short pkt (%d)\n", 425 state->unit, isize); 426 return DECOMP_ERROR; 427 } 428 429 /* Check the sequence number. */ 430 seq = get_unaligned_be16(ibuf + PPP_HDRLEN); 431 if (seq != (state->seqno & 0xffff)) { 432 if (state->debug) 433 printk(KERN_DEBUG "z_decompress%d: bad seq # %d, expected %d\n", 434 state->unit, seq, state->seqno & 0xffff); 435 return DECOMP_ERROR; 436 } 437 ++state->seqno; 438 439 /* 440 * Fill in the first part of the PPP header. The protocol field 441 * comes from the decompressed data. 442 */ 443 obuf[0] = PPP_ADDRESS(ibuf); 444 obuf[1] = PPP_CONTROL(ibuf); 445 obuf[2] = 0; 446 447 /* 448 * Set up to call inflate. We set avail_out to 1 initially so we can 449 * look at the first byte of the output and decide whether we have 450 * a 1-byte or 2-byte protocol field. 451 */ 452 state->strm.next_in = ibuf + PPP_HDRLEN + DEFLATE_OVHD; 453 state->strm.avail_in = isize - (PPP_HDRLEN + DEFLATE_OVHD); 454 state->strm.next_out = obuf + 3; 455 state->strm.avail_out = 1; 456 decode_proto = 1; 457 overflow = 0; 458 459 /* 460 * Call inflate, supplying more input or output as needed. 461 */ 462 for (;;) { 463 r = zlib_inflate(&state->strm, Z_PACKET_FLUSH); 464 if (r != Z_OK) { 465 if (state->debug) 466 printk(KERN_DEBUG "z_decompress%d: inflate returned %d (%s)\n", 467 state->unit, r, (state->strm.msg? state->strm.msg: "")); 468 return DECOMP_FATALERROR; 469 } 470 if (state->strm.avail_out != 0) 471 break; /* all done */ 472 if (decode_proto) { 473 state->strm.avail_out = osize - PPP_HDRLEN; 474 if ((obuf[3] & 1) == 0) { 475 /* 2-byte protocol field */ 476 obuf[2] = obuf[3]; 477 --state->strm.next_out; 478 ++state->strm.avail_out; 479 } 480 decode_proto = 0; 481 } else if (!overflow) { 482 /* 483 * We've filled up the output buffer; the only way to 484 * find out whether inflate has any more characters 485 * left is to give it another byte of output space. 486 */ 487 state->strm.next_out = overflow_buf; 488 state->strm.avail_out = 1; 489 overflow = 1; 490 } else { 491 if (state->debug) 492 printk(KERN_DEBUG "z_decompress%d: ran out of mru\n", 493 state->unit); 494 return DECOMP_FATALERROR; 495 } 496 } 497 498 if (decode_proto) { 499 if (state->debug) 500 printk(KERN_DEBUG "z_decompress%d: didn't get proto\n", 501 state->unit); 502 return DECOMP_ERROR; 503 } 504 505 olen = osize + overflow - state->strm.avail_out; 506 state->stats.unc_bytes += olen; 507 state->stats.unc_packets++; 508 state->stats.comp_bytes += isize; 509 state->stats.comp_packets++; 510 511 return olen; 512} 513 514/** 515 * z_incomp - add incompressible input data to the history. 516 * @arg: pointer to private state for the decompressor 517 * @ibuf: pointer to input packet data 518 * @icnt: length of input data. 519 */ 520static void z_incomp(void *arg, unsigned char *ibuf, int icnt) 521{ 522 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg; 523 int proto, r; 524 525 /* 526 * Check that the protocol is one we handle. 527 */ 528 proto = PPP_PROTOCOL(ibuf); 529 if (proto > 0x3fff || proto == 0xfd || proto == 0xfb) 530 return; 531 532 ++state->seqno; 533 534 /* 535 * We start at the either the 1st or 2nd byte of the protocol field, 536 * depending on whether the protocol value is compressible. 537 */ 538 state->strm.next_in = ibuf + 3; 539 state->strm.avail_in = icnt - 3; 540 if (proto > 0xff) { 541 --state->strm.next_in; 542 ++state->strm.avail_in; 543 } 544 545 r = zlib_inflateIncomp(&state->strm); 546 if (r != Z_OK) { 547 /* gak! */ 548 if (state->debug) { 549 printk(KERN_DEBUG "z_incomp%d: inflateIncomp returned %d (%s)\n", 550 state->unit, r, (state->strm.msg? state->strm.msg: "")); 551 } 552 return; 553 } 554 555 /* 556 * Update stats. 557 */ 558 state->stats.inc_bytes += icnt; 559 state->stats.inc_packets++; 560 state->stats.unc_bytes += icnt; 561 state->stats.unc_packets++; 562} 563 564/************************************************************* 565 * Module interface table 566 *************************************************************/ 567 568/* These are in ppp_generic.c */ 569extern int ppp_register_compressor (struct compressor *cp); 570extern void ppp_unregister_compressor (struct compressor *cp); 571 572/* 573 * Procedures exported to if_ppp.c. 574 */ 575static struct compressor ppp_deflate = { 576 .compress_proto = CI_DEFLATE, 577 .comp_alloc = z_comp_alloc, 578 .comp_free = z_comp_free, 579 .comp_init = z_comp_init, 580 .comp_reset = z_comp_reset, 581 .compress = z_compress, 582 .comp_stat = z_comp_stats, 583 .decomp_alloc = z_decomp_alloc, 584 .decomp_free = z_decomp_free, 585 .decomp_init = z_decomp_init, 586 .decomp_reset = z_decomp_reset, 587 .decompress = z_decompress, 588 .incomp = z_incomp, 589 .decomp_stat = z_comp_stats, 590 .owner = THIS_MODULE 591}; 592 593static struct compressor ppp_deflate_draft = { 594 .compress_proto = CI_DEFLATE_DRAFT, 595 .comp_alloc = z_comp_alloc, 596 .comp_free = z_comp_free, 597 .comp_init = z_comp_init, 598 .comp_reset = z_comp_reset, 599 .compress = z_compress, 600 .comp_stat = z_comp_stats, 601 .decomp_alloc = z_decomp_alloc, 602 .decomp_free = z_decomp_free, 603 .decomp_init = z_decomp_init, 604 .decomp_reset = z_decomp_reset, 605 .decompress = z_decompress, 606 .incomp = z_incomp, 607 .decomp_stat = z_comp_stats, 608 .owner = THIS_MODULE 609}; 610 611static int __init deflate_init(void) 612{ 613 int answer = ppp_register_compressor(&ppp_deflate); 614 if (answer == 0) 615 printk(KERN_INFO 616 "PPP Deflate Compression module registered\n"); 617 ppp_register_compressor(&ppp_deflate_draft); 618 return answer; 619} 620 621static void __exit deflate_cleanup(void) 622{ 623 ppp_unregister_compressor(&ppp_deflate); 624 ppp_unregister_compressor(&ppp_deflate_draft); 625} 626 627module_init(deflate_init); 628module_exit(deflate_cleanup); 629MODULE_LICENSE("Dual BSD/GPL"); 630MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE)); 631MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE_DRAFT)); 632