aboutsummaryrefslogtreecommitdiffstats
path: root/drivers/net/ppp/ppp_deflate.c
blob: 602c625d95d5e26ba0c79f9ae6af2dd92f1f3c93 (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
/*
 * ppp_deflate.c - interface the zlib procedures for Deflate compression
 * and decompression (as used by gzip) to the PPP code.
 *
 * Copyright 1994-1998 Paul Mackerras.
 *
 *  This program is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU General Public License
 *  version 2 as published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/vmalloc.h>
#include <linux/init.h>
#include <linux/string.h>

#include <linux/ppp_defs.h>
#include <linux/ppp-comp.h>

#include <linux/zlib.h>
#include <asm/unaligned.h>

/*
 * State for a Deflate (de)compressor.
 */
struct ppp_deflate_state {
    int		seqno;
    int		w_size;
    int		unit;
    int		mru;
    int		debug;
    z_stream	strm;
    struct compstat stats;
};

#define DEFLATE_OVHD	2		/* Deflate overhead/packet */

static void	*z_comp_alloc(unsigned char *options, int opt_len);
static void	*z_decomp_alloc(unsigned char *options, int opt_len);
static void	z_comp_free(void *state);
static void	z_decomp_free(void *state);
static int	z_comp_init(void *state, unsigned char *options,
				 int opt_len,
				 int unit, int hdrlen, int debug);
static int	z_decomp_init(void *state, unsigned char *options,
				   int opt_len,
				   int unit, int hdrlen, int mru, int debug);
static int	z_compress(void *state, unsigned char *rptr,
				unsigned char *obuf,
				int isize, int osize);
static void	z_incomp(void *state, unsigned char *ibuf, int icnt);
static int	z_decompress(void *state, unsigned char *ibuf,
				int isize, unsigned char *obuf, int osize);
static void	z_comp_reset(void *state);
static void	z_decomp_reset(void *state);
static void	z_comp_stats(void *state, struct compstat *stats);

/**
 *	z_comp_free - free the memory used by a compressor
 *	@arg:	pointer to the private state for the compressor.
 */
static void z_comp_free(void *arg)
{
	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;

	if (state) {
		zlib_deflateEnd(&state->strm);
		vfree(state->strm.workspace);
		kfree(state);
	}
}

/**
 *	z_comp_alloc - allocate space for a compressor.
 *	@options: pointer to CCP option data
 *	@opt_len: length of the CCP option at @options.
 *
 *	The @options pointer points to the a buffer containing the
 *	CCP option data for the compression being negotiated.  It is
 *	formatted according to RFC1979, and describes the window
 *	size that the peer is requesting that we use in compressing
 *	data to be sent to it.
 *
 *	Returns the pointer to the private state for the compressor,
 *	or NULL if we could not allocate enough memory.
 */
static void *z_comp_alloc(unsigned char *options, int opt_len)
{
	struct ppp_deflate_state *state;
	int w_size;

	if (opt_len != CILEN_DEFLATE ||
	    (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
	    options[1] != CILEN_DEFLATE ||
	    DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
	    options[3] != DEFLATE_CHK_SEQUENCE)
		return NULL;
	w_size = DEFLATE_SIZE(options[2]);
	if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
		return NULL;

	state = kzalloc(sizeof(*state),
						     GFP_KERNEL);
	if (state == NULL)
		return NULL;

	state->strm.next_in   = NULL;
	state->w_size         = w_size;
	state->strm.workspace = vmalloc(zlib_deflate_workspacesize(-w_size, 8));
	if (state->strm.workspace == NULL)
		goto out_free;

	if (zlib_deflateInit2(&state->strm, Z_DEFAULT_COMPRESSION,
			 DEFLATE_METHOD_VAL, -w_size, 8, Z_DEFAULT_STRATEGY)
	    != Z_OK)
		goto out_free;
	return (void *) state;

out_free:
	z_comp_free(state);
	return NULL;
}

/**
 *	z_comp_init - initialize a previously-allocated compressor.
 *	@arg:	pointer to the private state for the compressor
 *	@options: pointer to the CCP option data describing the
 *		compression that was negotiated with the peer
 *	@opt_len: length of the CCP option data at @options
 *	@unit:	PPP unit number for diagnostic messages
 *	@hdrlen: ignored (present for backwards compatibility)
 *	@debug:	debug flag; if non-zero, debug messages are printed.
 *
 *	The CCP options described by @options must match the options
 *	specified when the compressor was allocated.  The compressor
 *	history is reset.  Returns 0 for failure (CCP options don't
 *	match) or 1 for success.
 */
static int z_comp_init(void *arg, unsigned char *options, int opt_len,
		       int unit, int hdrlen, int debug)
{
	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;

	if (opt_len < CILEN_DEFLATE ||
	    (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
	    options[1] != CILEN_DEFLATE ||
	    DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
	    DEFLATE_SIZE(options[2]) != state->w_size ||
	    options[3] != DEFLATE_CHK_SEQUENCE)
		return 0;

	state->seqno = 0;
	state->unit  = unit;
	state->debug = debug;

	zlib_deflateReset(&state->strm);

	return 1;
}

/**
 *	z_comp_reset - reset a previously-allocated compressor.
 *	@arg:	pointer to private state for the compressor.
 *
 *	This clears the history for the compressor and makes it
 *	ready to start emitting a new compressed stream.
 */
static void z_comp_reset(void *arg)
{
	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;

	state->seqno = 0;
	zlib_deflateReset(&state->strm);
}

/**
 *	z_compress - compress a PPP packet with Deflate compression.
 *	@arg:	pointer to private state for the compressor
 *	@rptr:	uncompressed packet (input)
 *	@obuf:	compressed packet (output)
 *	@isize:	size of uncompressed packet
 *	@osize:	space available at @obuf
 *
 *	Returns the length of the compressed packet, or 0 if the
 *	packet is incompressible.
 */
static int z_compress(void *arg, unsigned char *rptr, unsigned char *obuf,
	       int isize, int osize)
{
	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
	int r, proto, off, olen, oavail;
	unsigned char *wptr;

	/*
	 * Check that the protocol is in the range we handle.
	 */
	proto = PPP_PROTOCOL(rptr);
	if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
		return 0;

	/* Don't generate compressed packets which are larger than
	   the uncompressed packet. */
	if (osize > isize)
		osize = isize;

	wptr = obuf;

	/*
	 * Copy over the PPP header and store the 2-byte sequence number.
	 */
	wptr[0] = PPP_ADDRESS(rptr);
	wptr[1] = PPP_CONTROL(rptr);
	put_unaligned_be16(PPP_COMP, wptr + 2);
	wptr += PPP_HDRLEN;
	put_unaligned_be16(state->seqno, wptr);
	wptr += DEFLATE_OVHD;
	olen = PPP_HDRLEN + DEFLATE_OVHD;
	state->strm.next_out = wptr;
	state->strm.avail_out = oavail = osize - olen;
	++state->seqno;

	off = (proto > 0xff) ? 2 : 3;	/* skip 1st proto byte if 0 */
	rptr += off;
	state->strm.next_in = rptr;
	state->strm.avail_in = (isize - off);

	for (;;) {
		r = zlib_deflate(&state->strm, Z_PACKET_FLUSH);
		if (r != Z_OK) {
			if (state->debug)
				printk(KERN_ERR
				       "z_compress: deflate returned %d\n", r);
			break;
		}
		if (state->strm.avail_out == 0) {
			olen += oavail;
			state->strm.next_out = NULL;
			state->strm.avail_out = oavail = 1000000;
		} else {
			break;		/* all done */
		}
	}
	olen += oavail - state->strm.avail_out;

	/*
	 * See if we managed to reduce the size of the packet.
	 */
	if (olen < isize) {
		state->stats.comp_bytes += olen;
		state->stats.comp_packets++;
	} else {
		state->stats.inc_bytes += isize;
		state->stats.inc_packets++;
		olen = 0;
	}
	state->stats.unc_bytes += isize;
	state->stats.unc_packets++;

	return olen;
}

/**
 *	z_comp_stats - return compression statistics for a compressor
 *		or decompressor.
 *	@arg:	pointer to private space for the (de)compressor
 *	@stats:	pointer to a struct compstat to receive the result.
 */
static void z_comp_stats(void *arg, struct compstat *stats)
{
	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;

	*stats = state->stats;
}

/**
 *	z_decomp_free - Free the memory used by a decompressor.
 *	@arg:	pointer to private space for the decompressor.
 */
static void z_decomp_free(void *arg)
{
	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;

	if (state) {
		zlib_inflateEnd(&state->strm);
		vfree(state->strm.workspace);
		kfree(state);
	}
}

/**
 *	z_decomp_alloc - allocate space for a decompressor.
 *	@options: pointer to CCP option data
 *	@opt_len: length of the CCP option at @options.
 *
 *	The @options pointer points to the a buffer containing the
 *	CCP option data for the compression being negotiated.  It is
 *	formatted according to RFC1979, and describes the window
 *	size that we are requesting the peer to use in compressing
 *	data to be sent to us.
 *
 *	Returns the pointer to the private state for the decompressor,
 *	or NULL if we could not allocate enough memory.
 */
static void *z_decomp_alloc(unsigned char *options, int opt_len)
{
	struct ppp_deflate_state *state;
	int w_size;

	if (opt_len != CILEN_DEFLATE ||
	    (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
	    options[1] != CILEN_DEFLATE ||
	    DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
	    options[3] != DEFLATE_CHK_SEQUENCE)
		return NULL;
	w_size = DEFLATE_SIZE(options[2]);
	if (w_size < DEFLATE_MIN_SIZE || w_size > DEFLATE_MAX_SIZE)
		return NULL;

	state = kzalloc(sizeof(*state), GFP_KERNEL);
	if (state == NULL)
		return NULL;

	state->w_size         = w_size;
	state->strm.next_out  = NULL;
	state->strm.workspace = vmalloc(zlib_inflate_workspacesize());
	if (state->strm.workspace == NULL)
		goto out_free;

	if (zlib_inflateInit2(&state->strm, -w_size) != Z_OK)
		goto out_free;
	return (void *) state;

out_free:
	z_decomp_free(state);
	return NULL;
}

/**
 *	z_decomp_init - initialize a previously-allocated decompressor.
 *	@arg:	pointer to the private state for the decompressor
 *	@options: pointer to the CCP option data describing the
 *		compression that was negotiated with the peer
 *	@opt_len: length of the CCP option data at @options
 *	@unit:	PPP unit number for diagnostic messages
 *	@hdrlen: ignored (present for backwards compatibility)
 *	@mru:	maximum length of decompressed packets
 *	@debug:	debug flag; if non-zero, debug messages are printed.
 *
 *	The CCP options described by @options must match the options
 *	specified when the decompressor was allocated.  The decompressor
 *	history is reset.  Returns 0 for failure (CCP options don't
 *	match) or 1 for success.
 */
static int z_decomp_init(void *arg, unsigned char *options, int opt_len,
			 int unit, int hdrlen, int mru, int debug)
{
	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;

	if (opt_len < CILEN_DEFLATE ||
	    (options[0] != CI_DEFLATE && options[0] != CI_DEFLATE_DRAFT) ||
	    options[1] != CILEN_DEFLATE ||
	    DEFLATE_METHOD(options[2]) != DEFLATE_METHOD_VAL ||
	    DEFLATE_SIZE(options[2]) != state->w_size ||
	    options[3] != DEFLATE_CHK_SEQUENCE)
		return 0;

	state->seqno = 0;
	state->unit  = unit;
	state->debug = debug;
	state->mru   = mru;

	zlib_inflateReset(&state->strm);

	return 1;
}

/**
 *	z_decomp_reset - reset a previously-allocated decompressor.
 *	@arg:	pointer to private state for the decompressor.
 *
 *	This clears the history for the decompressor and makes it
 *	ready to receive a new compressed stream.
 */
static void z_decomp_reset(void *arg)
{
	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;

	state->seqno = 0;
	zlib_inflateReset(&state->strm);
}

/**
 *	z_decompress - decompress a Deflate-compressed packet.
 *	@arg:	pointer to private state for the decompressor
 *	@ibuf:	pointer to input (compressed) packet data
 *	@isize:	length of input packet
 *	@obuf:	pointer to space for output (decompressed) packet
 *	@osize:	amount of space available at @obuf
 *
 * Because of patent problems, we return DECOMP_ERROR for errors
 * found by inspecting the input data and for system problems, but
 * DECOMP_FATALERROR for any errors which could possibly be said to
 * be being detected "after" decompression.  For DECOMP_ERROR,
 * we can issue a CCP reset-request; for DECOMP_FATALERROR, we may be
 * infringing a patent of Motorola's if we do, so we take CCP down
 * instead.
 *
 * Given that the frame has the correct sequence number and a good FCS,
 * errors such as invalid codes in the input most likely indicate a
 * bug, so we return DECOMP_FATALERROR for them in order to turn off
 * compression, even though they are detected by inspecting the input.
 */
static int z_decompress(void *arg, unsigned char *ibuf, int isize,
		 unsigned char *obuf, int osize)
{
	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
	int olen, seq, r;
	int decode_proto, overflow;
	unsigned char overflow_buf[1];

	if (isize <= PPP_HDRLEN + DEFLATE_OVHD) {
		if (state->debug)
			printk(KERN_DEBUG "z_decompress%d: short pkt (%d)\n",
			       state->unit, isize);
		return DECOMP_ERROR;
	}

	/* Check the sequence number. */
	seq = get_unaligned_be16(ibuf + PPP_HDRLEN);
	if (seq != (state->seqno & 0xffff)) {
		if (state->debug)
			printk(KERN_DEBUG "z_decompress%d: bad seq # %d, expected %d\n",
			       state->unit, seq, state->seqno & 0xffff);
		return DECOMP_ERROR;
	}
	++state->seqno;

	/*
	 * Fill in the first part of the PPP header.  The protocol field
	 * comes from the decompressed data.
	 */
	obuf[0] = PPP_ADDRESS(ibuf);
	obuf[1] = PPP_CONTROL(ibuf);
	obuf[2] = 0;

	/*
	 * Set up to call inflate.  We set avail_out to 1 initially so we can
	 * look at the first byte of the output and decide whether we have
	 * a 1-byte or 2-byte protocol field.
	 */
	state->strm.next_in = ibuf + PPP_HDRLEN + DEFLATE_OVHD;
	state->strm.avail_in = isize - (PPP_HDRLEN + DEFLATE_OVHD);
	state->strm.next_out = obuf + 3;
	state->strm.avail_out = 1;
	decode_proto = 1;
	overflow = 0;

	/*
	 * Call inflate, supplying more input or output as needed.
	 */
	for (;;) {
		r = zlib_inflate(&state->strm, Z_PACKET_FLUSH);
		if (r != Z_OK) {
			if (state->debug)
				printk(KERN_DEBUG "z_decompress%d: inflate returned %d (%s)\n",
				       state->unit, r, (state->strm.msg? state->strm.msg: ""));
			return DECOMP_FATALERROR;
		}
		if (state->strm.avail_out != 0)
			break;		/* all done */
		if (decode_proto) {
			state->strm.avail_out = osize - PPP_HDRLEN;
			if ((obuf[3] & 1) == 0) {
				/* 2-byte protocol field */
				obuf[2] = obuf[3];
				--state->strm.next_out;
				++state->strm.avail_out;
			}
			decode_proto = 0;
		} else if (!overflow) {
			/*
			 * We've filled up the output buffer; the only way to
			 * find out whether inflate has any more characters
			 * left is to give it another byte of output space.
			 */
			state->strm.next_out = overflow_buf;
			state->strm.avail_out = 1;
			overflow = 1;
		} else {
			if (state->debug)
				printk(KERN_DEBUG "z_decompress%d: ran out of mru\n",
				       state->unit);
			return DECOMP_FATALERROR;
		}
	}

	if (decode_proto) {
		if (state->debug)
			printk(KERN_DEBUG "z_decompress%d: didn't get proto\n",
			       state->unit);
		return DECOMP_ERROR;
	}

	olen = osize + overflow - state->strm.avail_out;
	state->stats.unc_bytes += olen;
	state->stats.unc_packets++;
	state->stats.comp_bytes += isize;
	state->stats.comp_packets++;

	return olen;
}

/**
 *	z_incomp - add incompressible input data to the history.
 *	@arg:	pointer to private state for the decompressor
 *	@ibuf:	pointer to input packet data
 *	@icnt:	length of input data.
 */
static void z_incomp(void *arg, unsigned char *ibuf, int icnt)
{
	struct ppp_deflate_state *state = (struct ppp_deflate_state *) arg;
	int proto, r;

	/*
	 * Check that the protocol is one we handle.
	 */
	proto = PPP_PROTOCOL(ibuf);
	if (proto > 0x3fff || proto == 0xfd || proto == 0xfb)
		return;

	++state->seqno;

	/*
	 * We start at the either the 1st or 2nd byte of the protocol field,
	 * depending on whether the protocol value is compressible.
	 */
	state->strm.next_in = ibuf + 3;
	state->strm.avail_in = icnt - 3;
	if (proto > 0xff) {
		--state->strm.next_in;
		++state->strm.avail_in;
	}

	r = zlib_inflateIncomp(&state->strm);
	if (r != Z_OK) {
		/* gak! */
		if (state->debug) {
			printk(KERN_DEBUG "z_incomp%d: inflateIncomp returned %d (%s)\n",
			       state->unit, r, (state->strm.msg? state->strm.msg: ""));
		}
		return;
	}

	/*
	 * Update stats.
	 */
	state->stats.inc_bytes += icnt;
	state->stats.inc_packets++;
	state->stats.unc_bytes += icnt;
	state->stats.unc_packets++;
}

/*************************************************************
 * Module interface table
 *************************************************************/

/* These are in ppp_generic.c */
extern int  ppp_register_compressor   (struct compressor *cp);
extern void ppp_unregister_compressor (struct compressor *cp);

/*
 * Procedures exported to if_ppp.c.
 */
static struct compressor ppp_deflate = {
	.compress_proto =	CI_DEFLATE,
	.comp_alloc =		z_comp_alloc,
	.comp_free =		z_comp_free,
	.comp_init =		z_comp_init,
	.comp_reset =		z_comp_reset,
	.compress =		z_compress,
	.comp_stat =		z_comp_stats,
	.decomp_alloc =		z_decomp_alloc,
	.decomp_free =		z_decomp_free,
	.decomp_init =		z_decomp_init,
	.decomp_reset =		z_decomp_reset,
	.decompress =		z_decompress,
	.incomp =		z_incomp,
	.decomp_stat =		z_comp_stats,
	.owner =		THIS_MODULE
};

static struct compressor ppp_deflate_draft = {
	.compress_proto =	CI_DEFLATE_DRAFT,
	.comp_alloc =		z_comp_alloc,
	.comp_free =		z_comp_free,
	.comp_init =		z_comp_init,
	.comp_reset =		z_comp_reset,
	.compress =		z_compress,
	.comp_stat =		z_comp_stats,
	.decomp_alloc =		z_decomp_alloc,
	.decomp_free =		z_decomp_free,
	.decomp_init =		z_decomp_init,
	.decomp_reset =		z_decomp_reset,
	.decompress =		z_decompress,
	.incomp =		z_incomp,
	.decomp_stat =		z_comp_stats,
	.owner =		THIS_MODULE
};

static int __init deflate_init(void)
{
        int answer = ppp_register_compressor(&ppp_deflate);
        if (answer == 0)
                printk(KERN_INFO
		       "PPP Deflate Compression module registered\n");
	ppp_register_compressor(&ppp_deflate_draft);
        return answer;
}

static void __exit deflate_cleanup(void)
{
	ppp_unregister_compressor(&ppp_deflate);
	ppp_unregister_compressor(&ppp_deflate_draft);
}

module_init(deflate_init);
module_exit(deflate_cleanup);
MODULE_LICENSE("Dual BSD/GPL");
MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE));
MODULE_ALIAS("ppp-compress-" __stringify(CI_DEFLATE_DRAFT));