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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * ppp_deflate.c - interface the zlib procedures for Deflate compression4 * and decompression (as used by gzip) to the PPP code.5 *6 * Copyright 1994-1998 Paul Mackerras.7 */8 9#include <linux/module.h>10#include <linux/slab.h>11#include <linux/vmalloc.h>12#include <linux/init.h>13#include <linux/string.h>14 15#include <linux/ppp_defs.h>16#include <linux/ppp-comp.h>17 18#include <linux/zlib.h>19#include <linux/unaligned.h>20 21/*22 * State for a Deflate (de)compressor.23 */24struct ppp_deflate_state {25 int seqno;26 int w_size;27 int unit;28 int mru;29 int debug;30 z_stream strm;31 struct compstat stats;32};33 34#define DEFLATE_OVHD 2 /* Deflate overhead/packet */35 36static void *z_comp_alloc(unsigned char *options, int opt_len);37static void *z_decomp_alloc(unsigned char *options, int opt_len);38static void z_comp_free(void *state);39static void z_decomp_free(void *state);40static int z_comp_init(void *state, unsigned char *options,41 int opt_len,42 int unit, int hdrlen, int debug);43static int z_decomp_init(void *state, unsigned char *options,44 int opt_len,45 int unit, int hdrlen, int mru, int debug);46static int z_compress(void *state, unsigned char *rptr,47 unsigned char *obuf,48 int isize, int osize);49static void z_incomp(void *state, unsigned char *ibuf, int icnt);50static int z_decompress(void *state, unsigned char *ibuf,51 int isize, unsigned char *obuf, int osize);52static void z_comp_reset(void *state);53static void z_decomp_reset(void *state);54static void z_comp_stats(void *state, struct compstat *stats);55 56/**57 * z_comp_free - free the memory used by a compressor58 * @arg: pointer to the private state for the compressor.59 */60static void z_comp_free(void *arg)61{62 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;63 64 if (state) {65 zlib_deflateEnd(&state->strm);66 vfree(state->strm.workspace);67 kfree(state);68 }69}70 71/**72 * z_comp_alloc - allocate space for a compressor.73 * @options: pointer to CCP option data74 * @opt_len: length of the CCP option at @options.75 *76 * The @options pointer points to the a buffer containing the77 * CCP option data for the compression being negotiated. It is78 * formatted according to RFC1979, and describes the window79 * size that the peer is requesting that we use in compressing80 * data to be sent to it.81 *82 * Returns the pointer to the private state for the compressor,83 * or NULL if we could not allocate enough memory.84 */85static void *z_comp_alloc(unsigned char *options, int opt_len)86{87 struct ppp_deflate_state *state;88 int w_size;89 90 if (opt_len != CILEN_DEFLATE ||91 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||92 options[1] != CILEN_DEFLATE ||93 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||94 options[3] != DEFLATE_CHK_SEQUENCE)95 return NULL;96 w_size = DEFLATE_SIZE(options[2]);97 if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)98 return NULL;99 100 state = kzalloc(sizeof(*state),101 GFP_KERNEL);102 if (state == NULL)103 return NULL;104 105 state->strm.next_in = NULL;106 state->w_size = w_size;107 state->strm.workspace = vmalloc(zlib_deflate_workspacesize(-w_size, 8));108 if (state->strm.workspace == NULL)109 goto out_free;110 111 if (zlib_deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION,112 DEFLATE_METHOD_VAL, -w_size, 8, Z_DEFAULT_STRATEGY)113 != Z_OK)114 goto out_free;115 return (void *) state;116 117out_free:118 z_comp_free(state);119 return NULL;120}121 122/**123 * z_comp_init - initialize a previously-allocated compressor.124 * @arg: pointer to the private state for the compressor125 * @options: pointer to the CCP option data describing the126 * compression that was negotiated with the peer127 * @opt_len: length of the CCP option data at @options128 * @unit: PPP unit number for diagnostic messages129 * @hdrlen: ignored (present for backwards compatibility)130 * @debug: debug flag; if non-zero, debug messages are printed.131 *132 * The CCP options described by @options must match the options133 * specified when the compressor was allocated. The compressor134 * history is reset. Returns 0 for failure (CCP options don't135 * match) or 1 for success.136 */137static int z_comp_init(void *arg, unsigned char *options, int opt_len,138 int unit, int hdrlen, int debug)139{140 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;141 142 if (opt_len < CILEN_DEFLATE ||143 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||144 options[1] != CILEN_DEFLATE ||145 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||146 DEFLATE_SIZE(options[2]) != state->w_size ||147 options[3] != DEFLATE_CHK_SEQUENCE)148 return 0;149 150 state->seqno = 0;151 state->unit = unit;152 state->debug = debug;153 154 zlib_deflateReset(&state->strm);155 156 return 1;157}158 159/**160 * z_comp_reset - reset a previously-allocated compressor.161 * @arg: pointer to private state for the compressor.162 *163 * This clears the history for the compressor and makes it164 * ready to start emitting a new compressed stream.165 */166static void z_comp_reset(void *arg)167{168 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;169 170 state->seqno = 0;171 zlib_deflateReset(&state->strm);172}173 174/**175 * z_compress - compress a PPP packet with Deflate compression.176 * @arg: pointer to private state for the compressor177 * @rptr: uncompressed packet (input)178 * @obuf: compressed packet (output)179 * @isize: size of uncompressed packet180 * @osize: space available at @obuf181 *182 * Returns the length of the compressed packet, or 0 if the183 * packet is incompressible.184 */185static int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf,186 int isize, int osize)187{188 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;189 int r, proto, off, olen, oavail;190 unsigned char *wptr;191 192 /*193 * Check that the protocol is in the range we handle.194 */195 proto = PPP_PROTOCOL(rptr);196 if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)197 return 0;198 199 /* Don't generate compressed packets which are larger than200 the uncompressed packet. */201 if (osize > isize)202 osize = isize;203 204 wptr = obuf;205 206 /*207 * Copy over the PPP header and store the 2-byte sequence number.208 */209 wptr[0] = PPP_ADDRESS(rptr);210 wptr[1] = PPP_CONTROL(rptr);211 put_unaligned_be16(PPP_COMP, wptr + 2);212 wptr += PPP_HDRLEN;213 put_unaligned_be16(state->seqno, wptr);214 wptr += DEFLATE_OVHD;215 olen = PPP_HDRLEN + DEFLATE_OVHD;216 state->strm.next_out = wptr;217 state->strm.avail_out = oavail = osize - olen;218 ++state->seqno;219 220 off = (proto > 0xff) ? 2 : 3; /* skip 1st proto byte if 0 */221 rptr += off;222 state->strm.next_in = rptr;223 state->strm.avail_in = (isize - off);224 225 for (;;) {226 r = zlib_deflate(&state->strm, Z_PACKET_FLUSH);227 if (r != Z_OK) {228 if (state->debug)229 printk(KERN_ERR230 "z_compress: deflate returned %d\n", r);231 break;232 }233 if (state->strm.avail_out == 0) {234 olen += oavail;235 state->strm.next_out = NULL;236 state->strm.avail_out = oavail = 1000000;237 } else {238 break; /* all done */239 }240 }241 olen += oavail - state->strm.avail_out;242 243 /*244 * See if we managed to reduce the size of the packet.245 */246 if (olen < isize && olen <= osize) {247 state->stats.comp_bytes += olen;248 state->stats.comp_packets++;249 } else {250 state->stats.inc_bytes += isize;251 state->stats.inc_packets++;252 olen = 0;253 }254 state->stats.unc_bytes += isize;255 state->stats.unc_packets++;256 257 return olen;258}259 260/**261 * z_comp_stats - return compression statistics for a compressor262 * or decompressor.263 * @arg: pointer to private space for the (de)compressor264 * @stats: pointer to a struct compstat to receive the result.265 */266static void z_comp_stats(void *arg, struct compstat *stats)267{268 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;269 270 *stats = state->stats;271}272 273/**274 * z_decomp_free - Free the memory used by a decompressor.275 * @arg: pointer to private space for the decompressor.276 */277static void z_decomp_free(void *arg)278{279 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;280 281 if (state) {282 vfree(state->strm.workspace);283 kfree(state);284 }285}286 287/**288 * z_decomp_alloc - allocate space for a decompressor.289 * @options: pointer to CCP option data290 * @opt_len: length of the CCP option at @options.291 *292 * The @options pointer points to the a buffer containing the293 * CCP option data for the compression being negotiated. It is294 * formatted according to RFC1979, and describes the window295 * size that we are requesting the peer to use in compressing296 * data to be sent to us.297 *298 * Returns the pointer to the private state for the decompressor,299 * or NULL if we could not allocate enough memory.300 */301static void *z_decomp_alloc(unsigned char *options, int opt_len)302{303 struct ppp_deflate_state *state;304 int w_size;305 306 if (opt_len != CILEN_DEFLATE ||307 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||308 options[1] != CILEN_DEFLATE ||309 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||310 options[3] != DEFLATE_CHK_SEQUENCE)311 return NULL;312 w_size = DEFLATE_SIZE(options[2]);313 if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)314 return NULL;315 316 state = kzalloc(sizeof(*state), GFP_KERNEL);317 if (state == NULL)318 return NULL;319 320 state->w_size = w_size;321 state->strm.next_out = NULL;322 state->strm.workspace = vmalloc(zlib_inflate_workspacesize());323 if (state->strm.workspace == NULL)324 goto out_free;325 326 if (zlib_inflateInit2(&state->strm, -w_size) != Z_OK)327 goto out_free;328 return (void *) state;329 330out_free:331 z_decomp_free(state);332 return NULL;333}334 335/**336 * z_decomp_init - initialize a previously-allocated decompressor.337 * @arg: pointer to the private state for the decompressor338 * @options: pointer to the CCP option data describing the339 * compression that was negotiated with the peer340 * @opt_len: length of the CCP option data at @options341 * @unit: PPP unit number for diagnostic messages342 * @hdrlen: ignored (present for backwards compatibility)343 * @mru: maximum length of decompressed packets344 * @debug: debug flag; if non-zero, debug messages are printed.345 *346 * The CCP options described by @options must match the options347 * specified when the decompressor was allocated. The decompressor348 * history is reset. Returns 0 for failure (CCP options don't349 * match) or 1 for success.350 */351static int z_decomp_init(void *arg, unsigned char *options, int opt_len,352 int unit, int hdrlen, int mru, int debug)353{354 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;355 356 if (opt_len < CILEN_DEFLATE ||357 (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||358 options[1] != CILEN_DEFLATE ||359 DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||360 DEFLATE_SIZE(options[2]) != state->w_size ||361 options[3] != DEFLATE_CHK_SEQUENCE)362 return 0;363 364 state->seqno = 0;365 state->unit = unit;366 state->debug = debug;367 state->mru = mru;368 369 zlib_inflateReset(&state->strm);370 371 return 1;372}373 374/**375 * z_decomp_reset - reset a previously-allocated decompressor.376 * @arg: pointer to private state for the decompressor.377 *378 * This clears the history for the decompressor and makes it379 * ready to receive a new compressed stream.380 */381static void z_decomp_reset(void *arg)382{383 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;384 385 state->seqno = 0;386 zlib_inflateReset(&state->strm);387}388 389/**390 * z_decompress - decompress a Deflate-compressed packet.391 * @arg: pointer to private state for the decompressor392 * @ibuf: pointer to input (compressed) packet data393 * @isize: length of input packet394 * @obuf: pointer to space for output (decompressed) packet395 * @osize: amount of space available at @obuf396 *397 * Because of patent problems, we return DECOMP_ERROR for errors398 * found by inspecting the input data and for system problems, but399 * DECOMP_FATALERROR for any errors which could possibly be said to400 * be being detected "after" decompression. For DECOMP_ERROR,401 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be402 * infringing a patent of Motorola's if we do, so we take CCP down403 * instead.404 *405 * Given that the frame has the correct sequence number and a good FCS,406 * errors such as invalid codes in the input most likely indicate a407 * bug, so we return DECOMP_FATALERROR for them in order to turn off408 * compression, even though they are detected by inspecting the input.409 */410static int z_decompress(void *arg, unsigned char *ibuf, int isize,411 unsigned char *obuf, int osize)412{413 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;414 int olen, seq, r;415 int decode_proto, overflow;416 unsigned char overflow_buf[1];417 418 if (isize <= PPP_HDRLEN + DEFLATE_OVHD) {419 if (state->debug)420 printk(KERN_DEBUG "z_decompress%d: short pkt (%d)\n",421 state->unit, isize);422 return DECOMP_ERROR;423 }424 425 /* Check the sequence number. */426 seq = get_unaligned_be16(ibuf + PPP_HDRLEN);427 if (seq != (state->seqno & 0xffff)) {428 if (state->debug)429 printk(KERN_DEBUG "z_decompress%d: bad seq # %d, expected %d\n",430 state->unit, seq, state->seqno & 0xffff);431 return DECOMP_ERROR;432 }433 ++state->seqno;434 435 /*436 * Fill in the first part of the PPP header. The protocol field437 * comes from the decompressed data.438 */439 obuf[0] = PPP_ADDRESS(ibuf);440 obuf[1] = PPP_CONTROL(ibuf);441 obuf[2] = 0;442 443 /*444 * Set up to call inflate. We set avail_out to 1 initially so we can445 * look at the first byte of the output and decide whether we have446 * a 1-byte or 2-byte protocol field.447 */448 state->strm.next_in = ibuf + PPP_HDRLEN + DEFLATE_OVHD;449 state->strm.avail_in = isize - (PPP_HDRLEN + DEFLATE_OVHD);450 state->strm.next_out = obuf + 3;451 state->strm.avail_out = 1;452 decode_proto = 1;453 overflow = 0;454 455 /*456 * Call inflate, supplying more input or output as needed.457 */458 for (;;) {459 r = zlib_inflate(&state->strm, Z_PACKET_FLUSH);460 if (r != Z_OK) {461 if (state->debug)462 printk(KERN_DEBUG "z_decompress%d: inflate returned %d (%s)\n",463 state->unit, r, (state->strm.msg? state->strm.msg: ""));464 return DECOMP_FATALERROR;465 }466 if (state->strm.avail_out != 0)467 break; /* all done */468 if (decode_proto) {469 state->strm.avail_out = osize - PPP_HDRLEN;470 if ((obuf[3] & 1) == 0) {471 /* 2-byte protocol field */472 obuf[2] = obuf[3];473 --state->strm.next_out;474 ++state->strm.avail_out;475 }476 decode_proto = 0;477 } else if (!overflow) {478 /*479 * We've filled up the output buffer; the only way to480 * find out whether inflate has any more characters481 * left is to give it another byte of output space.482 */483 state->strm.next_out = overflow_buf;484 state->strm.avail_out = 1;485 overflow = 1;486 } else {487 if (state->debug)488 printk(KERN_DEBUG "z_decompress%d: ran out of mru\n",489 state->unit);490 return DECOMP_FATALERROR;491 }492 }493 494 if (decode_proto) {495 if (state->debug)496 printk(KERN_DEBUG "z_decompress%d: didn't get proto\n",497 state->unit);498 return DECOMP_ERROR;499 }500 501 olen = osize + overflow - state->strm.avail_out;502 state->stats.unc_bytes += olen;503 state->stats.unc_packets++;504 state->stats.comp_bytes += isize;505 state->stats.comp_packets++;506 507 return olen;508}509 510/**511 * z_incomp - add incompressible input data to the history.512 * @arg: pointer to private state for the decompressor513 * @ibuf: pointer to input packet data514 * @icnt: length of input data.515 */516static void z_incomp(void *arg, unsigned char *ibuf, int icnt)517{518 struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;519 int proto, r;520 521 /*522 * Check that the protocol is one we handle.523 */524 proto = PPP_PROTOCOL(ibuf);525 if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)526 return;527 528 ++state->seqno;529 530 /*531 * We start at the either the 1st or 2nd byte of the protocol field,532 * depending on whether the protocol value is compressible.533 */534 state->strm.next_in = ibuf + 3;535 state->strm.avail_in = icnt - 3;536 if (proto > 0xff) {537 --state->strm.next_in;538 ++state->strm.avail_in;539 }540 541 r = zlib_inflateIncomp(&state->strm);542 if (r != Z_OK) {543 /* gak! */544 if (state->debug) {545 printk(KERN_DEBUG "z_incomp%d: inflateIncomp returned %d (%s)\n",546 state->unit, r, (state->strm.msg? state->strm.msg: ""));547 }548 return;549 }550 551 /*552 * Update stats.553 */554 state->stats.inc_bytes += icnt;555 state->stats.inc_packets++;556 state->stats.unc_bytes += icnt;557 state->stats.unc_packets++;558}559 560/*************************************************************561 * Module interface table562 *************************************************************/563 564/* These are in ppp_generic.c */565extern int ppp_register_compressor (struct compressor *cp);566extern void ppp_unregister_compressor (struct compressor *cp);567 568/*569 * Procedures exported to if_ppp.c.570 */571static struct compressor ppp_deflate = {572 .compress_proto = CI_DEFLATE,573 .comp_alloc = z_comp_alloc,574 .comp_free = z_comp_free,575 .comp_init = z_comp_init,576 .comp_reset = z_comp_reset,577 .compress = z_compress,578 .comp_stat = z_comp_stats,579 .decomp_alloc = z_decomp_alloc,580 .decomp_free = z_decomp_free,581 .decomp_init = z_decomp_init,582 .decomp_reset = z_decomp_reset,583 .decompress = z_decompress,584 .incomp = z_incomp,585 .decomp_stat = z_comp_stats,586 .owner = THIS_MODULE587};588 589static struct compressor ppp_deflate_draft = {590 .compress_proto = CI_DEFLATE_DRAFT,591 .comp_alloc = z_comp_alloc,592 .comp_free = z_comp_free,593 .comp_init = z_comp_init,594 .comp_reset = z_comp_reset,595 .compress = z_compress,596 .comp_stat = z_comp_stats,597 .decomp_alloc = z_decomp_alloc,598 .decomp_free = z_decomp_free,599 .decomp_init = z_decomp_init,600 .decomp_reset = z_decomp_reset,601 .decompress = z_decompress,602 .incomp = z_incomp,603 .decomp_stat = z_comp_stats,604 .owner = THIS_MODULE605};606 607static int __init deflate_init(void)608{609 int rc;610 611 rc = ppp_register_compressor(&ppp_deflate);612 if (rc)613 return rc;614 615 rc = ppp_register_compressor(&ppp_deflate_draft);616 if (rc) {617 ppp_unregister_compressor(&ppp_deflate);618 return rc;619 }620 621 pr_info("PPP Deflate Compression module registered\n");622 return 0;623}624 625static void __exit deflate_cleanup(void)626{627 ppp_unregister_compressor(&ppp_deflate);628 ppp_unregister_compressor(&ppp_deflate_draft);629}630 631module_init(deflate_init);632module_exit(deflate_cleanup);633MODULE_DESCRIPTION("PPP Deflate compression module");634MODULE_LICENSE("Dual BSD/GPL");635MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE));636MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE_DRAFT));637