1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * ppp_deflate.c - interface the zlib procedures for Deflate compression
4 * 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 <asm/unaligned.h>
20
21 /*
22 * State for a Deflate (de)compressor.
23 */
24 struct 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
36 static void *z_comp_alloc(unsigned char *options, int opt_len);
37 static void *z_decomp_alloc(unsigned char *options, int opt_len);
38 static void z_comp_free(void *state);
39 static void z_decomp_free(void *state);
40 static int z_comp_init(void *state, unsigned char *options,
41 int opt_len,
42 int unit, int hdrlen, int debug);
43 static int z_decomp_init(void *state, unsigned char *options,
44 int opt_len,
45 int unit, int hdrlen, int mru, int debug);
46 static int z_compress(void *state, unsigned char *rptr,
47 unsigned char *obuf,
48 int isize, int osize);
49 static void z_incomp(void *state, unsigned char *ibuf, int icnt);
50 static int z_decompress(void *state, unsigned char *ibuf,
51 int isize, unsigned char *obuf, int osize);
52 static void z_comp_reset(void *state);
53 static void z_decomp_reset(void *state);
54 static void z_comp_stats(void *state, struct compstat *stats);
55
56 /**
57 * z_comp_free - free the memory used by a compressor
58 * @arg: pointer to the private state for the compressor.
59 */
z_comp_free(void * arg)60 static 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 data
74 * @opt_len: length of the CCP option at @options.
75 *
76 * The @options pointer points to the a buffer containing the
77 * CCP option data for the compression being negotiated. It is
78 * formatted according to RFC1979, and describes the window
79 * size that the peer is requesting that we use in compressing
80 * 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 */
z_comp_alloc(unsigned char * options,int opt_len)85 static 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
117 out_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 compressor
125 * @options: pointer to the CCP option data describing the
126 * compression that was negotiated with the peer
127 * @opt_len: length of the CCP option data at @options
128 * @unit: PPP unit number for diagnostic messages
129 * @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 options
133 * specified when the compressor was allocated. The compressor
134 * history is reset. Returns 0 for failure (CCP options don't
135 * match) or 1 for success.
136 */
z_comp_init(void * arg,unsigned char * options,int opt_len,int unit,int hdrlen,int debug)137 static 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 it
164 * ready to start emitting a new compressed stream.
165 */
z_comp_reset(void * arg)166 static 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 compressor
177 * @rptr: uncompressed packet (input)
178 * @obuf: compressed packet (output)
179 * @isize: size of uncompressed packet
180 * @osize: space available at @obuf
181 *
182 * Returns the length of the compressed packet, or 0 if the
183 * packet is incompressible.
184 */
z_compress(void * arg,unsigned char * rptr,unsigned char * obuf,int isize,int osize)185 static 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 than
200 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_ERR
230 "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 compressor
262 * or decompressor.
263 * @arg: pointer to private space for the (de)compressor
264 * @stats: pointer to a struct compstat to receive the result.
265 */
z_comp_stats(void * arg,struct compstat * stats)266 static 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 */
z_decomp_free(void * arg)277 static 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 data
290 * @opt_len: length of the CCP option at @options.
291 *
292 * The @options pointer points to the a buffer containing the
293 * CCP option data for the compression being negotiated. It is
294 * formatted according to RFC1979, and describes the window
295 * size that we are requesting the peer to use in compressing
296 * 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 */
z_decomp_alloc(unsigned char * options,int opt_len)301 static 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
330 out_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 decompressor
338 * @options: pointer to the CCP option data describing the
339 * compression that was negotiated with the peer
340 * @opt_len: length of the CCP option data at @options
341 * @unit: PPP unit number for diagnostic messages
342 * @hdrlen: ignored (present for backwards compatibility)
343 * @mru: maximum length of decompressed packets
344 * @debug: debug flag; if non-zero, debug messages are printed.
345 *
346 * The CCP options described by @options must match the options
347 * specified when the decompressor was allocated. The decompressor
348 * history is reset. Returns 0 for failure (CCP options don't
349 * match) or 1 for success.
350 */
z_decomp_init(void * arg,unsigned char * options,int opt_len,int unit,int hdrlen,int mru,int debug)351 static 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 it
379 * ready to receive a new compressed stream.
380 */
z_decomp_reset(void * arg)381 static 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 decompressor
392 * @ibuf: pointer to input (compressed) packet data
393 * @isize: length of input packet
394 * @obuf: pointer to space for output (decompressed) packet
395 * @osize: amount of space available at @obuf
396 *
397 * Because of patent problems, we return DECOMP_ERROR for errors
398 * found by inspecting the input data and for system problems, but
399 * DECOMP_FATALERROR for any errors which could possibly be said to
400 * be being detected "after" decompression. For DECOMP_ERROR,
401 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
402 * infringing a patent of Motorola's if we do, so we take CCP down
403 * 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 a
407 * bug, so we return DECOMP_FATALERROR for them in order to turn off
408 * compression, even though they are detected by inspecting the input.
409 */
z_decompress(void * arg,unsigned char * ibuf,int isize,unsigned char * obuf,int osize)410 static 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 field
437 * 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 can
445 * look at the first byte of the output and decide whether we have
446 * 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 to
480 * find out whether inflate has any more characters
481 * 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 decompressor
513 * @ibuf: pointer to input packet data
514 * @icnt: length of input data.
515 */
z_incomp(void * arg,unsigned char * ibuf,int icnt)516 static 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 table
562 *************************************************************/
563
564 /* These are in ppp_generic.c */
565 extern int ppp_register_compressor (struct compressor *cp);
566 extern void ppp_unregister_compressor (struct compressor *cp);
567
568 /*
569 * Procedures exported to if_ppp.c.
570 */
571 static 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_MODULE
587 };
588
589 static 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_MODULE
605 };
606
deflate_init(void)607 static 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
deflate_cleanup(void)625 static void __exit deflate_cleanup(void)
626 {
627 ppp_unregister_compressor(&ppp_deflate);
628 ppp_unregister_compressor(&ppp_deflate_draft);
629 }
630
631 module_init(deflate_init);
632 module_exit(deflate_cleanup);
633 MODULE_LICENSE("Dual BSD/GPL");
634 MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE));
635 MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE_DRAFT));
636