linux/drivers/net/ppp/ppp_deflate.c
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   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 && olen <= osize) {
 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