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1/*
2 * ppp_mppe.c - interface MPPE to the PPP code.
3 * This version is for use with Linux kernel 2.6.14+
4 *
5 * By Frank Cusack <fcusack@fcusack.com>.
6 * Copyright (c) 2002,2003,2004 Google, Inc.
7 * All rights reserved.
8 *
9 * License:
10 * Permission to use, copy, modify, and distribute this software and its
11 * documentation is hereby granted, provided that the above copyright
12 * notice appears in all copies. This software is provided without any
13 * warranty, express or implied.
14 *
15 * ALTERNATIVELY, provided that this notice is retained in full, this product
16 * may be distributed under the terms of the GNU General Public License (GPL),
17 * in which case the provisions of the GPL apply INSTEAD OF those given above.
18 *
19 * This program is free software; you can redistribute it and/or modify
20 * it under the terms of the GNU General Public License as published by
21 * the Free Software Foundation; either version 2 of the License, or
22 * (at your option) any later version.
23 *
24 * This program is distributed in the hope that it will be useful,
25 * but WITHOUT ANY WARRANTY; without even the implied warranty of
26 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
27 * GNU General Public License for more details.
28 *
29 * You should have received a copy of the GNU General Public License
30 * along with this program; if not, see <http://www.gnu.org/licenses/>.
31 *
32 *
33 * Changelog:
34 * 08/12/05 - Matt Domsch <Matt_Domsch@dell.com>
35 * Only need extra skb padding on transmit, not receive.
36 * 06/18/04 - Matt Domsch <Matt_Domsch@dell.com>, Oleg Makarenko <mole@quadra.ru>
37 * Use Linux kernel 2.6 arc4 and sha1 routines rather than
38 * providing our own.
39 * 2/15/04 - TS: added #include <version.h> and testing for Kernel
40 * version before using
41 * MOD_DEC_USAGE_COUNT/MOD_INC_USAGE_COUNT which are
42 * deprecated in 2.6
43 */
44
45#include <linux/err.h>
46#include <linux/module.h>
47#include <linux/kernel.h>
48#include <linux/init.h>
49#include <linux/types.h>
50#include <linux/slab.h>
51#include <linux/string.h>
52#include <linux/crypto.h>
53#include <linux/mm.h>
54#include <linux/ppp_defs.h>
55#include <linux/ppp-comp.h>
56#include <linux/scatterlist.h>
57#include <asm/unaligned.h>
58
59#include "ppp_mppe.h"
60
61MODULE_AUTHOR("Frank Cusack <fcusack@fcusack.com>");
62MODULE_DESCRIPTION("Point-to-Point Protocol Microsoft Point-to-Point Encryption support");
63MODULE_LICENSE("Dual BSD/GPL");
64MODULE_ALIAS("ppp-compress-" __stringify(CI_MPPE));
65MODULE_VERSION("1.0.2");
66
67static unsigned int
68setup_sg(struct scatterlist *sg, const void *address, unsigned int length)
69{
70 sg_set_buf(sg, address, length);
71 return length;
72}
73
74#define SHA1_PAD_SIZE 40
75
76/*
77 * kernel crypto API needs its arguments to be in kmalloc'd memory, not in the module
78 * static data area. That means sha_pad needs to be kmalloc'd.
79 */
80
81struct sha_pad {
82 unsigned char sha_pad1[SHA1_PAD_SIZE];
83 unsigned char sha_pad2[SHA1_PAD_SIZE];
84};
85static struct sha_pad *sha_pad;
86
87static inline void sha_pad_init(struct sha_pad *shapad)
88{
89 memset(shapad->sha_pad1, 0x00, sizeof(shapad->sha_pad1));
90 memset(shapad->sha_pad2, 0xF2, sizeof(shapad->sha_pad2));
91}
92
93/*
94 * State for an MPPE (de)compressor.
95 */
96struct ppp_mppe_state {
97 struct crypto_blkcipher *arc4;
98 struct crypto_hash *sha1;
99 unsigned char *sha1_digest;
100 unsigned char master_key[MPPE_MAX_KEY_LEN];
101 unsigned char session_key[MPPE_MAX_KEY_LEN];
102 unsigned keylen; /* key length in bytes */
103 /* NB: 128-bit == 16, 40-bit == 8! */
104 /* If we want to support 56-bit, */
105 /* the unit has to change to bits */
106 unsigned char bits; /* MPPE control bits */
107 unsigned ccount; /* 12-bit coherency count (seqno) */
108 unsigned stateful; /* stateful mode flag */
109 int discard; /* stateful mode packet loss flag */
110 int sanity_errors; /* take down LCP if too many */
111 int unit;
112 int debug;
113 struct compstat stats;
114};
115
116/* struct ppp_mppe_state.bits definitions */
117#define MPPE_BIT_A 0x80 /* Encryption table were (re)inititalized */
118#define MPPE_BIT_B 0x40 /* MPPC only (not implemented) */
119#define MPPE_BIT_C 0x20 /* MPPC only (not implemented) */
120#define MPPE_BIT_D 0x10 /* This is an encrypted frame */
121
122#define MPPE_BIT_FLUSHED MPPE_BIT_A
123#define MPPE_BIT_ENCRYPTED MPPE_BIT_D
124
125#define MPPE_BITS(p) ((p)[4] & 0xf0)
126#define MPPE_CCOUNT(p) ((((p)[4] & 0x0f) << 8) + (p)[5])
127#define MPPE_CCOUNT_SPACE 0x1000 /* The size of the ccount space */
128
129#define MPPE_OVHD 2 /* MPPE overhead/packet */
130#define SANITY_MAX 1600 /* Max bogon factor we will tolerate */
131
132/*
133 * Key Derivation, from RFC 3078, RFC 3079.
134 * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
135 */
136static void get_new_key_from_sha(struct ppp_mppe_state * state)
137{
138 struct hash_desc desc;
139 struct scatterlist sg[4];
140 unsigned int nbytes;
141
142 sg_init_table(sg, 4);
143
144 nbytes = setup_sg(&sg[0], state->master_key, state->keylen);
145 nbytes += setup_sg(&sg[1], sha_pad->sha_pad1,
146 sizeof(sha_pad->sha_pad1));
147 nbytes += setup_sg(&sg[2], state->session_key, state->keylen);
148 nbytes += setup_sg(&sg[3], sha_pad->sha_pad2,
149 sizeof(sha_pad->sha_pad2));
150
151 desc.tfm = state->sha1;
152 desc.flags = 0;
153
154 crypto_hash_digest(&desc, sg, nbytes, state->sha1_digest);
155}
156
157/*
158 * Perform the MPPE rekey algorithm, from RFC 3078, sec. 7.3.
159 * Well, not what's written there, but rather what they meant.
160 */
161static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
162{
163 struct scatterlist sg_in[1], sg_out[1];
164 struct blkcipher_desc desc = { .tfm = state->arc4 };
165
166 get_new_key_from_sha(state);
167 if (!initial_key) {
168 crypto_blkcipher_setkey(state->arc4, state->sha1_digest,
169 state->keylen);
170 sg_init_table(sg_in, 1);
171 sg_init_table(sg_out, 1);
172 setup_sg(sg_in, state->sha1_digest, state->keylen);
173 setup_sg(sg_out, state->session_key, state->keylen);
174 if (crypto_blkcipher_encrypt(&desc, sg_out, sg_in,
175 state->keylen) != 0) {
176 printk(KERN_WARNING "mppe_rekey: cipher_encrypt failed\n");
177 }
178 } else {
179 memcpy(state->session_key, state->sha1_digest, state->keylen);
180 }
181 if (state->keylen == 8) {
182 /* See RFC 3078 */
183 state->session_key[0] = 0xd1;
184 state->session_key[1] = 0x26;
185 state->session_key[2] = 0x9e;
186 }
187 crypto_blkcipher_setkey(state->arc4, state->session_key, state->keylen);
188}
189
190/*
191 * Allocate space for a (de)compressor.
192 */
193static void *mppe_alloc(unsigned char *options, int optlen)
194{
195 struct ppp_mppe_state *state;
196 unsigned int digestsize;
197
198 if (optlen != CILEN_MPPE + sizeof(state->master_key) ||
199 options[0] != CI_MPPE || options[1] != CILEN_MPPE)
200 goto out;
201
202 state = kzalloc(sizeof(*state), GFP_KERNEL);
203 if (state == NULL)
204 goto out;
205
206
207 state->arc4 = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
208 if (IS_ERR(state->arc4)) {
209 state->arc4 = NULL;
210 goto out_free;
211 }
212
213 state->sha1 = crypto_alloc_hash("sha1", 0, CRYPTO_ALG_ASYNC);
214 if (IS_ERR(state->sha1)) {
215 state->sha1 = NULL;
216 goto out_free;
217 }
218
219 digestsize = crypto_hash_digestsize(state->sha1);
220 if (digestsize < MPPE_MAX_KEY_LEN)
221 goto out_free;
222
223 state->sha1_digest = kmalloc(digestsize, GFP_KERNEL);
224 if (!state->sha1_digest)
225 goto out_free;
226
227 /* Save keys. */
228 memcpy(state->master_key, &options[CILEN_MPPE],
229 sizeof(state->master_key));
230 memcpy(state->session_key, state->master_key,
231 sizeof(state->master_key));
232
233 /*
234 * We defer initial key generation until mppe_init(), as mppe_alloc()
235 * is called frequently during negotiation.
236 */
237
238 return (void *)state;
239
240 out_free:
241 if (state->sha1_digest)
242 kfree(state->sha1_digest);
243 if (state->sha1)
244 crypto_free_hash(state->sha1);
245 if (state->arc4)
246 crypto_free_blkcipher(state->arc4);
247 kfree(state);
248 out:
249 return NULL;
250}
251
252/*
253 * Deallocate space for a (de)compressor.
254 */
255static void mppe_free(void *arg)
256{
257 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
258 if (state) {
259 if (state->sha1_digest)
260 kfree(state->sha1_digest);
261 if (state->sha1)
262 crypto_free_hash(state->sha1);
263 if (state->arc4)
264 crypto_free_blkcipher(state->arc4);
265 kfree(state);
266 }
267}
268
269/*
270 * Initialize (de)compressor state.
271 */
272static int
273mppe_init(void *arg, unsigned char *options, int optlen, int unit, int debug,
274 const char *debugstr)
275{
276 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
277 unsigned char mppe_opts;
278
279 if (optlen != CILEN_MPPE ||
280 options[0] != CI_MPPE || options[1] != CILEN_MPPE)
281 return 0;
282
283 MPPE_CI_TO_OPTS(&options[2], mppe_opts);
284 if (mppe_opts & MPPE_OPT_128)
285 state->keylen = 16;
286 else if (mppe_opts & MPPE_OPT_40)
287 state->keylen = 8;
288 else {
289 printk(KERN_WARNING "%s[%d]: unknown key length\n", debugstr,
290 unit);
291 return 0;
292 }
293 if (mppe_opts & MPPE_OPT_STATEFUL)
294 state->stateful = 1;
295
296 /* Generate the initial session key. */
297 mppe_rekey(state, 1);
298
299 if (debug) {
300 int i;
301 char mkey[sizeof(state->master_key) * 2 + 1];
302 char skey[sizeof(state->session_key) * 2 + 1];
303
304 printk(KERN_DEBUG "%s[%d]: initialized with %d-bit %s mode\n",
305 debugstr, unit, (state->keylen == 16) ? 128 : 40,
306 (state->stateful) ? "stateful" : "stateless");
307
308 for (i = 0; i < sizeof(state->master_key); i++)
309 sprintf(mkey + i * 2, "%02x", state->master_key[i]);
310 for (i = 0; i < sizeof(state->session_key); i++)
311 sprintf(skey + i * 2, "%02x", state->session_key[i]);
312 printk(KERN_DEBUG
313 "%s[%d]: keys: master: %s initial session: %s\n",
314 debugstr, unit, mkey, skey);
315 }
316
317 /*
318 * Initialize the coherency count. The initial value is not specified
319 * in RFC 3078, but we can make a reasonable assumption that it will
320 * start at 0. Setting it to the max here makes the comp/decomp code
321 * do the right thing (determined through experiment).
322 */
323 state->ccount = MPPE_CCOUNT_SPACE - 1;
324
325 /*
326 * Note that even though we have initialized the key table, we don't
327 * set the FLUSHED bit. This is contrary to RFC 3078, sec. 3.1.
328 */
329 state->bits = MPPE_BIT_ENCRYPTED;
330
331 state->unit = unit;
332 state->debug = debug;
333
334 return 1;
335}
336
337static int
338mppe_comp_init(void *arg, unsigned char *options, int optlen, int unit,
339 int hdrlen, int debug)
340{
341 /* ARGSUSED */
342 return mppe_init(arg, options, optlen, unit, debug, "mppe_comp_init");
343}
344
345/*
346 * We received a CCP Reset-Request (actually, we are sending a Reset-Ack),
347 * tell the compressor to rekey. Note that we MUST NOT rekey for
348 * every CCP Reset-Request; we only rekey on the next xmit packet.
349 * We might get multiple CCP Reset-Requests if our CCP Reset-Ack is lost.
350 * So, rekeying for every CCP Reset-Request is broken as the peer will not
351 * know how many times we've rekeyed. (If we rekey and THEN get another
352 * CCP Reset-Request, we must rekey again.)
353 */
354static void mppe_comp_reset(void *arg)
355{
356 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
357
358 state->bits |= MPPE_BIT_FLUSHED;
359}
360
361/*
362 * Compress (encrypt) a packet.
363 * It's strange to call this a compressor, since the output is always
364 * MPPE_OVHD + 2 bytes larger than the input.
365 */
366static int
367mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf,
368 int isize, int osize)
369{
370 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
371 struct blkcipher_desc desc = { .tfm = state->arc4 };
372 int proto;
373 struct scatterlist sg_in[1], sg_out[1];
374
375 /*
376 * Check that the protocol is in the range we handle.
377 */
378 proto = PPP_PROTOCOL(ibuf);
379 if (proto < 0x0021 || proto > 0x00fa)
380 return 0;
381
382 /* Make sure we have enough room to generate an encrypted packet. */
383 if (osize < isize + MPPE_OVHD + 2) {
384 /* Drop the packet if we should encrypt it, but can't. */
385 printk(KERN_DEBUG "mppe_compress[%d]: osize too small! "
386 "(have: %d need: %d)\n", state->unit,
387 osize, osize + MPPE_OVHD + 2);
388 return -1;
389 }
390
391 osize = isize + MPPE_OVHD + 2;
392
393 /*
394 * Copy over the PPP header and set control bits.
395 */
396 obuf[0] = PPP_ADDRESS(ibuf);
397 obuf[1] = PPP_CONTROL(ibuf);
398 put_unaligned_be16(PPP_COMP, obuf + 2);
399 obuf += PPP_HDRLEN;
400
401 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
402 if (state->debug >= 7)
403 printk(KERN_DEBUG "mppe_compress[%d]: ccount %d\n", state->unit,
404 state->ccount);
405 put_unaligned_be16(state->ccount, obuf);
406
407 if (!state->stateful || /* stateless mode */
408 ((state->ccount & 0xff) == 0xff) || /* "flag" packet */
409 (state->bits & MPPE_BIT_FLUSHED)) { /* CCP Reset-Request */
410 /* We must rekey */
411 if (state->debug && state->stateful)
412 printk(KERN_DEBUG "mppe_compress[%d]: rekeying\n",
413 state->unit);
414 mppe_rekey(state, 0);
415 state->bits |= MPPE_BIT_FLUSHED;
416 }
417 obuf[0] |= state->bits;
418 state->bits &= ~MPPE_BIT_FLUSHED; /* reset for next xmit */
419
420 obuf += MPPE_OVHD;
421 ibuf += 2; /* skip to proto field */
422 isize -= 2;
423
424 /* Encrypt packet */
425 sg_init_table(sg_in, 1);
426 sg_init_table(sg_out, 1);
427 setup_sg(sg_in, ibuf, isize);
428 setup_sg(sg_out, obuf, osize);
429 if (crypto_blkcipher_encrypt(&desc, sg_out, sg_in, isize) != 0) {
430 printk(KERN_DEBUG "crypto_cypher_encrypt failed\n");
431 return -1;
432 }
433
434 state->stats.unc_bytes += isize;
435 state->stats.unc_packets++;
436 state->stats.comp_bytes += osize;
437 state->stats.comp_packets++;
438
439 return osize;
440}
441
442/*
443 * Since every frame grows by MPPE_OVHD + 2 bytes, this is always going
444 * to look bad ... and the longer the link is up the worse it will get.
445 */
446static void mppe_comp_stats(void *arg, struct compstat *stats)
447{
448 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
449
450 *stats = state->stats;
451}
452
453static int
454mppe_decomp_init(void *arg, unsigned char *options, int optlen, int unit,
455 int hdrlen, int mru, int debug)
456{
457 /* ARGSUSED */
458 return mppe_init(arg, options, optlen, unit, debug, "mppe_decomp_init");
459}
460
461/*
462 * We received a CCP Reset-Ack. Just ignore it.
463 */
464static void mppe_decomp_reset(void *arg)
465{
466 /* ARGSUSED */
467 return;
468}
469
470/*
471 * Decompress (decrypt) an MPPE packet.
472 */
473static int
474mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
475 int osize)
476{
477 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
478 struct blkcipher_desc desc = { .tfm = state->arc4 };
479 unsigned ccount;
480 int flushed = MPPE_BITS(ibuf) & MPPE_BIT_FLUSHED;
481 int sanity = 0;
482 struct scatterlist sg_in[1], sg_out[1];
483
484 if (isize <= PPP_HDRLEN + MPPE_OVHD) {
485 if (state->debug)
486 printk(KERN_DEBUG
487 "mppe_decompress[%d]: short pkt (%d)\n",
488 state->unit, isize);
489 return DECOMP_ERROR;
490 }
491
492 /*
493 * Make sure we have enough room to decrypt the packet.
494 * Note that for our test we only subtract 1 byte whereas in
495 * mppe_compress() we added 2 bytes (+MPPE_OVHD);
496 * this is to account for possible PFC.
497 */
498 if (osize < isize - MPPE_OVHD - 1) {
499 printk(KERN_DEBUG "mppe_decompress[%d]: osize too small! "
500 "(have: %d need: %d)\n", state->unit,
501 osize, isize - MPPE_OVHD - 1);
502 return DECOMP_ERROR;
503 }
504 osize = isize - MPPE_OVHD - 2; /* assume no PFC */
505
506 ccount = MPPE_CCOUNT(ibuf);
507 if (state->debug >= 7)
508 printk(KERN_DEBUG "mppe_decompress[%d]: ccount %d\n",
509 state->unit, ccount);
510
511 /* sanity checks -- terminate with extreme prejudice */
512 if (!(MPPE_BITS(ibuf) & MPPE_BIT_ENCRYPTED)) {
513 printk(KERN_DEBUG
514 "mppe_decompress[%d]: ENCRYPTED bit not set!\n",
515 state->unit);
516 state->sanity_errors += 100;
517 sanity = 1;
518 }
519 if (!state->stateful && !flushed) {
520 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set in "
521 "stateless mode!\n", state->unit);
522 state->sanity_errors += 100;
523 sanity = 1;
524 }
525 if (state->stateful && ((ccount & 0xff) == 0xff) && !flushed) {
526 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set on "
527 "flag packet!\n", state->unit);
528 state->sanity_errors += 100;
529 sanity = 1;
530 }
531
532 if (sanity) {
533 if (state->sanity_errors < SANITY_MAX)
534 return DECOMP_ERROR;
535 else
536 /*
537 * Take LCP down if the peer is sending too many bogons.
538 * We don't want to do this for a single or just a few
539 * instances since it could just be due to packet corruption.
540 */
541 return DECOMP_FATALERROR;
542 }
543
544 /*
545 * Check the coherency count.
546 */
547
548 if (!state->stateful) {
549 /* RFC 3078, sec 8.1. Rekey for every packet. */
550 while (state->ccount != ccount) {
551 mppe_rekey(state, 0);
552 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
553 }
554 } else {
555 /* RFC 3078, sec 8.2. */
556 if (!state->discard) {
557 /* normal state */
558 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
559 if (ccount != state->ccount) {
560 /*
561 * (ccount > state->ccount)
562 * Packet loss detected, enter the discard state.
563 * Signal the peer to rekey (by sending a CCP Reset-Request).
564 */
565 state->discard = 1;
566 return DECOMP_ERROR;
567 }
568 } else {
569 /* discard state */
570 if (!flushed) {
571 /* ccp.c will be silent (no additional CCP Reset-Requests). */
572 return DECOMP_ERROR;
573 } else {
574 /* Rekey for every missed "flag" packet. */
575 while ((ccount & ~0xff) !=
576 (state->ccount & ~0xff)) {
577 mppe_rekey(state, 0);
578 state->ccount =
579 (state->ccount +
580 256) % MPPE_CCOUNT_SPACE;
581 }
582
583 /* reset */
584 state->discard = 0;
585 state->ccount = ccount;
586 /*
587 * Another problem with RFC 3078 here. It implies that the
588 * peer need not send a Reset-Ack packet. But RFC 1962
589 * requires it. Hopefully, M$ does send a Reset-Ack; even
590 * though it isn't required for MPPE synchronization, it is
591 * required to reset CCP state.
592 */
593 }
594 }
595 if (flushed)
596 mppe_rekey(state, 0);
597 }
598
599 /*
600 * Fill in the first part of the PPP header. The protocol field
601 * comes from the decrypted data.
602 */
603 obuf[0] = PPP_ADDRESS(ibuf); /* +1 */
604 obuf[1] = PPP_CONTROL(ibuf); /* +1 */
605 obuf += 2;
606 ibuf += PPP_HDRLEN + MPPE_OVHD;
607 isize -= PPP_HDRLEN + MPPE_OVHD; /* -6 */
608 /* net osize: isize-4 */
609
610 /*
611 * Decrypt the first byte in order to check if it is
612 * a compressed or uncompressed protocol field.
613 */
614 sg_init_table(sg_in, 1);
615 sg_init_table(sg_out, 1);
616 setup_sg(sg_in, ibuf, 1);
617 setup_sg(sg_out, obuf, 1);
618 if (crypto_blkcipher_decrypt(&desc, sg_out, sg_in, 1) != 0) {
619 printk(KERN_DEBUG "crypto_cypher_decrypt failed\n");
620 return DECOMP_ERROR;
621 }
622
623 /*
624 * Do PFC decompression.
625 * This would be nicer if we were given the actual sk_buff
626 * instead of a char *.
627 */
628 if ((obuf[0] & 0x01) != 0) {
629 obuf[1] = obuf[0];
630 obuf[0] = 0;
631 obuf++;
632 osize++;
633 }
634
635 /* And finally, decrypt the rest of the packet. */
636 setup_sg(sg_in, ibuf + 1, isize - 1);
637 setup_sg(sg_out, obuf + 1, osize - 1);
638 if (crypto_blkcipher_decrypt(&desc, sg_out, sg_in, isize - 1)) {
639 printk(KERN_DEBUG "crypto_cypher_decrypt failed\n");
640 return DECOMP_ERROR;
641 }
642
643 state->stats.unc_bytes += osize;
644 state->stats.unc_packets++;
645 state->stats.comp_bytes += isize;
646 state->stats.comp_packets++;
647
648 /* good packet credit */
649 state->sanity_errors >>= 1;
650
651 return osize;
652}
653
654/*
655 * Incompressible data has arrived (this should never happen!).
656 * We should probably drop the link if the protocol is in the range
657 * of what should be encrypted. At the least, we should drop this
658 * packet. (How to do this?)
659 */
660static void mppe_incomp(void *arg, unsigned char *ibuf, int icnt)
661{
662 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
663
664 if (state->debug &&
665 (PPP_PROTOCOL(ibuf) >= 0x0021 && PPP_PROTOCOL(ibuf) <= 0x00fa))
666 printk(KERN_DEBUG
667 "mppe_incomp[%d]: incompressible (unencrypted) data! "
668 "(proto %04x)\n", state->unit, PPP_PROTOCOL(ibuf));
669
670 state->stats.inc_bytes += icnt;
671 state->stats.inc_packets++;
672 state->stats.unc_bytes += icnt;
673 state->stats.unc_packets++;
674}
675
676/*************************************************************
677 * Module interface table
678 *************************************************************/
679
680/*
681 * Procedures exported to if_ppp.c.
682 */
683static struct compressor ppp_mppe = {
684 .compress_proto = CI_MPPE,
685 .comp_alloc = mppe_alloc,
686 .comp_free = mppe_free,
687 .comp_init = mppe_comp_init,
688 .comp_reset = mppe_comp_reset,
689 .compress = mppe_compress,
690 .comp_stat = mppe_comp_stats,
691 .decomp_alloc = mppe_alloc,
692 .decomp_free = mppe_free,
693 .decomp_init = mppe_decomp_init,
694 .decomp_reset = mppe_decomp_reset,
695 .decompress = mppe_decompress,
696 .incomp = mppe_incomp,
697 .decomp_stat = mppe_comp_stats,
698 .owner = THIS_MODULE,
699 .comp_extra = MPPE_PAD,
700};
701
702/*
703 * ppp_mppe_init()
704 *
705 * Prior to allowing load, try to load the arc4 and sha1 crypto
706 * libraries. The actual use will be allocated later, but
707 * this way the module will fail to insmod if they aren't available.
708 */
709
710static int __init ppp_mppe_init(void)
711{
712 int answer;
713 if (!(crypto_has_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC) &&
714 crypto_has_hash("sha1", 0, CRYPTO_ALG_ASYNC)))
715 return -ENODEV;
716
717 sha_pad = kmalloc(sizeof(struct sha_pad), GFP_KERNEL);
718 if (!sha_pad)
719 return -ENOMEM;
720 sha_pad_init(sha_pad);
721
722 answer = ppp_register_compressor(&ppp_mppe);
723
724 if (answer == 0)
725 printk(KERN_INFO "PPP MPPE Compression module registered\n");
726 else
727 kfree(sha_pad);
728
729 return answer;
730}
731
732static void __exit ppp_mppe_cleanup(void)
733{
734 ppp_unregister_compressor(&ppp_mppe);
735 kfree(sha_pad);
736}
737
738module_init(ppp_mppe_init);
739module_exit(ppp_mppe_cleanup);
1/*
2 * ppp_mppe.c - interface MPPE to the PPP code.
3 * This version is for use with Linux kernel 2.6.14+
4 *
5 * By Frank Cusack <fcusack@fcusack.com>.
6 * Copyright (c) 2002,2003,2004 Google, Inc.
7 * All rights reserved.
8 *
9 * License:
10 * Permission to use, copy, modify, and distribute this software and its
11 * documentation is hereby granted, provided that the above copyright
12 * notice appears in all copies. This software is provided without any
13 * warranty, express or implied.
14 *
15 * ALTERNATIVELY, provided that this notice is retained in full, this product
16 * may be distributed under the terms of the GNU General Public License (GPL),
17 * in which case the provisions of the GPL apply INSTEAD OF those given above.
18 *
19 * This program is free software; you can redistribute it and/or modify
20 * it under the terms of the GNU General Public License as published by
21 * the Free Software Foundation; either version 2 of the License, or
22 * (at your option) any later version.
23 *
24 * This program is distributed in the hope that it will be useful,
25 * but WITHOUT ANY WARRANTY; without even the implied warranty of
26 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
27 * GNU General Public License for more details.
28 *
29 * You should have received a copy of the GNU General Public License
30 * along with this program; if not, see <http://www.gnu.org/licenses/>.
31 *
32 *
33 * Changelog:
34 * 08/12/05 - Matt Domsch <Matt_Domsch@dell.com>
35 * Only need extra skb padding on transmit, not receive.
36 * 06/18/04 - Matt Domsch <Matt_Domsch@dell.com>, Oleg Makarenko <mole@quadra.ru>
37 * Use Linux kernel 2.6 arc4 and sha1 routines rather than
38 * providing our own.
39 * 2/15/04 - TS: added #include <version.h> and testing for Kernel
40 * version before using
41 * MOD_DEC_USAGE_COUNT/MOD_INC_USAGE_COUNT which are
42 * deprecated in 2.6
43 */
44
45#include <crypto/arc4.h>
46#include <crypto/hash.h>
47#include <linux/err.h>
48#include <linux/fips.h>
49#include <linux/module.h>
50#include <linux/kernel.h>
51#include <linux/init.h>
52#include <linux/types.h>
53#include <linux/slab.h>
54#include <linux/string.h>
55#include <linux/mm.h>
56#include <linux/ppp_defs.h>
57#include <linux/ppp-comp.h>
58#include <linux/scatterlist.h>
59#include <asm/unaligned.h>
60
61#include "ppp_mppe.h"
62
63MODULE_AUTHOR("Frank Cusack <fcusack@fcusack.com>");
64MODULE_DESCRIPTION("Point-to-Point Protocol Microsoft Point-to-Point Encryption support");
65MODULE_LICENSE("Dual BSD/GPL");
66MODULE_ALIAS("ppp-compress-" __stringify(CI_MPPE));
67MODULE_VERSION("1.0.2");
68
69#define SHA1_PAD_SIZE 40
70
71/*
72 * kernel crypto API needs its arguments to be in kmalloc'd memory, not in the module
73 * static data area. That means sha_pad needs to be kmalloc'd.
74 */
75
76struct sha_pad {
77 unsigned char sha_pad1[SHA1_PAD_SIZE];
78 unsigned char sha_pad2[SHA1_PAD_SIZE];
79};
80static struct sha_pad *sha_pad;
81
82static inline void sha_pad_init(struct sha_pad *shapad)
83{
84 memset(shapad->sha_pad1, 0x00, sizeof(shapad->sha_pad1));
85 memset(shapad->sha_pad2, 0xF2, sizeof(shapad->sha_pad2));
86}
87
88/*
89 * State for an MPPE (de)compressor.
90 */
91struct ppp_mppe_state {
92 struct arc4_ctx arc4;
93 struct shash_desc *sha1;
94 unsigned char *sha1_digest;
95 unsigned char master_key[MPPE_MAX_KEY_LEN];
96 unsigned char session_key[MPPE_MAX_KEY_LEN];
97 unsigned keylen; /* key length in bytes */
98 /* NB: 128-bit == 16, 40-bit == 8! */
99 /* If we want to support 56-bit, */
100 /* the unit has to change to bits */
101 unsigned char bits; /* MPPE control bits */
102 unsigned ccount; /* 12-bit coherency count (seqno) */
103 unsigned stateful; /* stateful mode flag */
104 int discard; /* stateful mode packet loss flag */
105 int sanity_errors; /* take down LCP if too many */
106 int unit;
107 int debug;
108 struct compstat stats;
109};
110
111/* struct ppp_mppe_state.bits definitions */
112#define MPPE_BIT_A 0x80 /* Encryption table were (re)inititalized */
113#define MPPE_BIT_B 0x40 /* MPPC only (not implemented) */
114#define MPPE_BIT_C 0x20 /* MPPC only (not implemented) */
115#define MPPE_BIT_D 0x10 /* This is an encrypted frame */
116
117#define MPPE_BIT_FLUSHED MPPE_BIT_A
118#define MPPE_BIT_ENCRYPTED MPPE_BIT_D
119
120#define MPPE_BITS(p) ((p)[4] & 0xf0)
121#define MPPE_CCOUNT(p) ((((p)[4] & 0x0f) << 8) + (p)[5])
122#define MPPE_CCOUNT_SPACE 0x1000 /* The size of the ccount space */
123
124#define MPPE_OVHD 2 /* MPPE overhead/packet */
125#define SANITY_MAX 1600 /* Max bogon factor we will tolerate */
126
127/*
128 * Key Derivation, from RFC 3078, RFC 3079.
129 * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
130 */
131static void get_new_key_from_sha(struct ppp_mppe_state * state)
132{
133 crypto_shash_init(state->sha1);
134 crypto_shash_update(state->sha1, state->master_key,
135 state->keylen);
136 crypto_shash_update(state->sha1, sha_pad->sha_pad1,
137 sizeof(sha_pad->sha_pad1));
138 crypto_shash_update(state->sha1, state->session_key,
139 state->keylen);
140 crypto_shash_update(state->sha1, sha_pad->sha_pad2,
141 sizeof(sha_pad->sha_pad2));
142 crypto_shash_final(state->sha1, state->sha1_digest);
143}
144
145/*
146 * Perform the MPPE rekey algorithm, from RFC 3078, sec. 7.3.
147 * Well, not what's written there, but rather what they meant.
148 */
149static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
150{
151 get_new_key_from_sha(state);
152 if (!initial_key) {
153 arc4_setkey(&state->arc4, state->sha1_digest, state->keylen);
154 arc4_crypt(&state->arc4, state->session_key, state->sha1_digest,
155 state->keylen);
156 } else {
157 memcpy(state->session_key, state->sha1_digest, state->keylen);
158 }
159 if (state->keylen == 8) {
160 /* See RFC 3078 */
161 state->session_key[0] = 0xd1;
162 state->session_key[1] = 0x26;
163 state->session_key[2] = 0x9e;
164 }
165 arc4_setkey(&state->arc4, state->session_key, state->keylen);
166}
167
168/*
169 * Allocate space for a (de)compressor.
170 */
171static void *mppe_alloc(unsigned char *options, int optlen)
172{
173 struct ppp_mppe_state *state;
174 struct crypto_shash *shash;
175 unsigned int digestsize;
176
177 if (optlen != CILEN_MPPE + sizeof(state->master_key) ||
178 options[0] != CI_MPPE || options[1] != CILEN_MPPE ||
179 fips_enabled)
180 goto out;
181
182 state = kzalloc(sizeof(*state), GFP_KERNEL);
183 if (state == NULL)
184 goto out;
185
186
187 shash = crypto_alloc_shash("sha1", 0, 0);
188 if (IS_ERR(shash))
189 goto out_free;
190
191 state->sha1 = kmalloc(sizeof(*state->sha1) +
192 crypto_shash_descsize(shash),
193 GFP_KERNEL);
194 if (!state->sha1) {
195 crypto_free_shash(shash);
196 goto out_free;
197 }
198 state->sha1->tfm = shash;
199
200 digestsize = crypto_shash_digestsize(shash);
201 if (digestsize < MPPE_MAX_KEY_LEN)
202 goto out_free;
203
204 state->sha1_digest = kmalloc(digestsize, GFP_KERNEL);
205 if (!state->sha1_digest)
206 goto out_free;
207
208 /* Save keys. */
209 memcpy(state->master_key, &options[CILEN_MPPE],
210 sizeof(state->master_key));
211 memcpy(state->session_key, state->master_key,
212 sizeof(state->master_key));
213
214 /*
215 * We defer initial key generation until mppe_init(), as mppe_alloc()
216 * is called frequently during negotiation.
217 */
218
219 return (void *)state;
220
221out_free:
222 kfree(state->sha1_digest);
223 if (state->sha1) {
224 crypto_free_shash(state->sha1->tfm);
225 kzfree(state->sha1);
226 }
227 kfree(state);
228out:
229 return NULL;
230}
231
232/*
233 * Deallocate space for a (de)compressor.
234 */
235static void mppe_free(void *arg)
236{
237 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
238 if (state) {
239 kfree(state->sha1_digest);
240 crypto_free_shash(state->sha1->tfm);
241 kzfree(state->sha1);
242 kzfree(state);
243 }
244}
245
246/*
247 * Initialize (de)compressor state.
248 */
249static int
250mppe_init(void *arg, unsigned char *options, int optlen, int unit, int debug,
251 const char *debugstr)
252{
253 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
254 unsigned char mppe_opts;
255
256 if (optlen != CILEN_MPPE ||
257 options[0] != CI_MPPE || options[1] != CILEN_MPPE)
258 return 0;
259
260 MPPE_CI_TO_OPTS(&options[2], mppe_opts);
261 if (mppe_opts & MPPE_OPT_128)
262 state->keylen = 16;
263 else if (mppe_opts & MPPE_OPT_40)
264 state->keylen = 8;
265 else {
266 printk(KERN_WARNING "%s[%d]: unknown key length\n", debugstr,
267 unit);
268 return 0;
269 }
270 if (mppe_opts & MPPE_OPT_STATEFUL)
271 state->stateful = 1;
272
273 /* Generate the initial session key. */
274 mppe_rekey(state, 1);
275
276 if (debug) {
277 printk(KERN_DEBUG "%s[%d]: initialized with %d-bit %s mode\n",
278 debugstr, unit, (state->keylen == 16) ? 128 : 40,
279 (state->stateful) ? "stateful" : "stateless");
280 printk(KERN_DEBUG
281 "%s[%d]: keys: master: %*phN initial session: %*phN\n",
282 debugstr, unit,
283 (int)sizeof(state->master_key), state->master_key,
284 (int)sizeof(state->session_key), state->session_key);
285 }
286
287 /*
288 * Initialize the coherency count. The initial value is not specified
289 * in RFC 3078, but we can make a reasonable assumption that it will
290 * start at 0. Setting it to the max here makes the comp/decomp code
291 * do the right thing (determined through experiment).
292 */
293 state->ccount = MPPE_CCOUNT_SPACE - 1;
294
295 /*
296 * Note that even though we have initialized the key table, we don't
297 * set the FLUSHED bit. This is contrary to RFC 3078, sec. 3.1.
298 */
299 state->bits = MPPE_BIT_ENCRYPTED;
300
301 state->unit = unit;
302 state->debug = debug;
303
304 return 1;
305}
306
307static int
308mppe_comp_init(void *arg, unsigned char *options, int optlen, int unit,
309 int hdrlen, int debug)
310{
311 /* ARGSUSED */
312 return mppe_init(arg, options, optlen, unit, debug, "mppe_comp_init");
313}
314
315/*
316 * We received a CCP Reset-Request (actually, we are sending a Reset-Ack),
317 * tell the compressor to rekey. Note that we MUST NOT rekey for
318 * every CCP Reset-Request; we only rekey on the next xmit packet.
319 * We might get multiple CCP Reset-Requests if our CCP Reset-Ack is lost.
320 * So, rekeying for every CCP Reset-Request is broken as the peer will not
321 * know how many times we've rekeyed. (If we rekey and THEN get another
322 * CCP Reset-Request, we must rekey again.)
323 */
324static void mppe_comp_reset(void *arg)
325{
326 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
327
328 state->bits |= MPPE_BIT_FLUSHED;
329}
330
331/*
332 * Compress (encrypt) a packet.
333 * It's strange to call this a compressor, since the output is always
334 * MPPE_OVHD + 2 bytes larger than the input.
335 */
336static int
337mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf,
338 int isize, int osize)
339{
340 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
341 int proto;
342
343 /*
344 * Check that the protocol is in the range we handle.
345 */
346 proto = PPP_PROTOCOL(ibuf);
347 if (proto < 0x0021 || proto > 0x00fa)
348 return 0;
349
350 /* Make sure we have enough room to generate an encrypted packet. */
351 if (osize < isize + MPPE_OVHD + 2) {
352 /* Drop the packet if we should encrypt it, but can't. */
353 printk(KERN_DEBUG "mppe_compress[%d]: osize too small! "
354 "(have: %d need: %d)\n", state->unit,
355 osize, osize + MPPE_OVHD + 2);
356 return -1;
357 }
358
359 osize = isize + MPPE_OVHD + 2;
360
361 /*
362 * Copy over the PPP header and set control bits.
363 */
364 obuf[0] = PPP_ADDRESS(ibuf);
365 obuf[1] = PPP_CONTROL(ibuf);
366 put_unaligned_be16(PPP_COMP, obuf + 2);
367 obuf += PPP_HDRLEN;
368
369 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
370 if (state->debug >= 7)
371 printk(KERN_DEBUG "mppe_compress[%d]: ccount %d\n", state->unit,
372 state->ccount);
373 put_unaligned_be16(state->ccount, obuf);
374
375 if (!state->stateful || /* stateless mode */
376 ((state->ccount & 0xff) == 0xff) || /* "flag" packet */
377 (state->bits & MPPE_BIT_FLUSHED)) { /* CCP Reset-Request */
378 /* We must rekey */
379 if (state->debug && state->stateful)
380 printk(KERN_DEBUG "mppe_compress[%d]: rekeying\n",
381 state->unit);
382 mppe_rekey(state, 0);
383 state->bits |= MPPE_BIT_FLUSHED;
384 }
385 obuf[0] |= state->bits;
386 state->bits &= ~MPPE_BIT_FLUSHED; /* reset for next xmit */
387
388 obuf += MPPE_OVHD;
389 ibuf += 2; /* skip to proto field */
390 isize -= 2;
391
392 arc4_crypt(&state->arc4, obuf, ibuf, isize);
393
394 state->stats.unc_bytes += isize;
395 state->stats.unc_packets++;
396 state->stats.comp_bytes += osize;
397 state->stats.comp_packets++;
398
399 return osize;
400}
401
402/*
403 * Since every frame grows by MPPE_OVHD + 2 bytes, this is always going
404 * to look bad ... and the longer the link is up the worse it will get.
405 */
406static void mppe_comp_stats(void *arg, struct compstat *stats)
407{
408 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
409
410 *stats = state->stats;
411}
412
413static int
414mppe_decomp_init(void *arg, unsigned char *options, int optlen, int unit,
415 int hdrlen, int mru, int debug)
416{
417 /* ARGSUSED */
418 return mppe_init(arg, options, optlen, unit, debug, "mppe_decomp_init");
419}
420
421/*
422 * We received a CCP Reset-Ack. Just ignore it.
423 */
424static void mppe_decomp_reset(void *arg)
425{
426 /* ARGSUSED */
427 return;
428}
429
430/*
431 * Decompress (decrypt) an MPPE packet.
432 */
433static int
434mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
435 int osize)
436{
437 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
438 unsigned ccount;
439 int flushed = MPPE_BITS(ibuf) & MPPE_BIT_FLUSHED;
440
441 if (isize <= PPP_HDRLEN + MPPE_OVHD) {
442 if (state->debug)
443 printk(KERN_DEBUG
444 "mppe_decompress[%d]: short pkt (%d)\n",
445 state->unit, isize);
446 return DECOMP_ERROR;
447 }
448
449 /*
450 * Make sure we have enough room to decrypt the packet.
451 * Note that for our test we only subtract 1 byte whereas in
452 * mppe_compress() we added 2 bytes (+MPPE_OVHD);
453 * this is to account for possible PFC.
454 */
455 if (osize < isize - MPPE_OVHD - 1) {
456 printk(KERN_DEBUG "mppe_decompress[%d]: osize too small! "
457 "(have: %d need: %d)\n", state->unit,
458 osize, isize - MPPE_OVHD - 1);
459 return DECOMP_ERROR;
460 }
461 osize = isize - MPPE_OVHD - 2; /* assume no PFC */
462
463 ccount = MPPE_CCOUNT(ibuf);
464 if (state->debug >= 7)
465 printk(KERN_DEBUG "mppe_decompress[%d]: ccount %d\n",
466 state->unit, ccount);
467
468 /* sanity checks -- terminate with extreme prejudice */
469 if (!(MPPE_BITS(ibuf) & MPPE_BIT_ENCRYPTED)) {
470 printk(KERN_DEBUG
471 "mppe_decompress[%d]: ENCRYPTED bit not set!\n",
472 state->unit);
473 state->sanity_errors += 100;
474 goto sanity_error;
475 }
476 if (!state->stateful && !flushed) {
477 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set in "
478 "stateless mode!\n", state->unit);
479 state->sanity_errors += 100;
480 goto sanity_error;
481 }
482 if (state->stateful && ((ccount & 0xff) == 0xff) && !flushed) {
483 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set on "
484 "flag packet!\n", state->unit);
485 state->sanity_errors += 100;
486 goto sanity_error;
487 }
488
489 /*
490 * Check the coherency count.
491 */
492
493 if (!state->stateful) {
494 /* Discard late packet */
495 if ((ccount - state->ccount) % MPPE_CCOUNT_SPACE
496 > MPPE_CCOUNT_SPACE / 2) {
497 state->sanity_errors++;
498 goto sanity_error;
499 }
500
501 /* RFC 3078, sec 8.1. Rekey for every packet. */
502 while (state->ccount != ccount) {
503 mppe_rekey(state, 0);
504 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
505 }
506 } else {
507 /* RFC 3078, sec 8.2. */
508 if (!state->discard) {
509 /* normal state */
510 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
511 if (ccount != state->ccount) {
512 /*
513 * (ccount > state->ccount)
514 * Packet loss detected, enter the discard state.
515 * Signal the peer to rekey (by sending a CCP Reset-Request).
516 */
517 state->discard = 1;
518 return DECOMP_ERROR;
519 }
520 } else {
521 /* discard state */
522 if (!flushed) {
523 /* ccp.c will be silent (no additional CCP Reset-Requests). */
524 return DECOMP_ERROR;
525 } else {
526 /* Rekey for every missed "flag" packet. */
527 while ((ccount & ~0xff) !=
528 (state->ccount & ~0xff)) {
529 mppe_rekey(state, 0);
530 state->ccount =
531 (state->ccount +
532 256) % MPPE_CCOUNT_SPACE;
533 }
534
535 /* reset */
536 state->discard = 0;
537 state->ccount = ccount;
538 /*
539 * Another problem with RFC 3078 here. It implies that the
540 * peer need not send a Reset-Ack packet. But RFC 1962
541 * requires it. Hopefully, M$ does send a Reset-Ack; even
542 * though it isn't required for MPPE synchronization, it is
543 * required to reset CCP state.
544 */
545 }
546 }
547 if (flushed)
548 mppe_rekey(state, 0);
549 }
550
551 /*
552 * Fill in the first part of the PPP header. The protocol field
553 * comes from the decrypted data.
554 */
555 obuf[0] = PPP_ADDRESS(ibuf); /* +1 */
556 obuf[1] = PPP_CONTROL(ibuf); /* +1 */
557 obuf += 2;
558 ibuf += PPP_HDRLEN + MPPE_OVHD;
559 isize -= PPP_HDRLEN + MPPE_OVHD; /* -6 */
560 /* net osize: isize-4 */
561
562 /*
563 * Decrypt the first byte in order to check if it is
564 * a compressed or uncompressed protocol field.
565 */
566 arc4_crypt(&state->arc4, obuf, ibuf, 1);
567
568 /*
569 * Do PFC decompression.
570 * This would be nicer if we were given the actual sk_buff
571 * instead of a char *.
572 */
573 if ((obuf[0] & 0x01) != 0) {
574 obuf[1] = obuf[0];
575 obuf[0] = 0;
576 obuf++;
577 osize++;
578 }
579
580 /* And finally, decrypt the rest of the packet. */
581 arc4_crypt(&state->arc4, obuf + 1, ibuf + 1, isize - 1);
582
583 state->stats.unc_bytes += osize;
584 state->stats.unc_packets++;
585 state->stats.comp_bytes += isize;
586 state->stats.comp_packets++;
587
588 /* good packet credit */
589 state->sanity_errors >>= 1;
590
591 return osize;
592
593sanity_error:
594 if (state->sanity_errors < SANITY_MAX)
595 return DECOMP_ERROR;
596 else
597 /* Take LCP down if the peer is sending too many bogons.
598 * We don't want to do this for a single or just a few
599 * instances since it could just be due to packet corruption.
600 */
601 return DECOMP_FATALERROR;
602}
603
604/*
605 * Incompressible data has arrived (this should never happen!).
606 * We should probably drop the link if the protocol is in the range
607 * of what should be encrypted. At the least, we should drop this
608 * packet. (How to do this?)
609 */
610static void mppe_incomp(void *arg, unsigned char *ibuf, int icnt)
611{
612 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
613
614 if (state->debug &&
615 (PPP_PROTOCOL(ibuf) >= 0x0021 && PPP_PROTOCOL(ibuf) <= 0x00fa))
616 printk(KERN_DEBUG
617 "mppe_incomp[%d]: incompressible (unencrypted) data! "
618 "(proto %04x)\n", state->unit, PPP_PROTOCOL(ibuf));
619
620 state->stats.inc_bytes += icnt;
621 state->stats.inc_packets++;
622 state->stats.unc_bytes += icnt;
623 state->stats.unc_packets++;
624}
625
626/*************************************************************
627 * Module interface table
628 *************************************************************/
629
630/*
631 * Procedures exported to if_ppp.c.
632 */
633static struct compressor ppp_mppe = {
634 .compress_proto = CI_MPPE,
635 .comp_alloc = mppe_alloc,
636 .comp_free = mppe_free,
637 .comp_init = mppe_comp_init,
638 .comp_reset = mppe_comp_reset,
639 .compress = mppe_compress,
640 .comp_stat = mppe_comp_stats,
641 .decomp_alloc = mppe_alloc,
642 .decomp_free = mppe_free,
643 .decomp_init = mppe_decomp_init,
644 .decomp_reset = mppe_decomp_reset,
645 .decompress = mppe_decompress,
646 .incomp = mppe_incomp,
647 .decomp_stat = mppe_comp_stats,
648 .owner = THIS_MODULE,
649 .comp_extra = MPPE_PAD,
650};
651
652/*
653 * ppp_mppe_init()
654 *
655 * Prior to allowing load, try to load the arc4 and sha1 crypto
656 * libraries. The actual use will be allocated later, but
657 * this way the module will fail to insmod if they aren't available.
658 */
659
660static int __init ppp_mppe_init(void)
661{
662 int answer;
663 if (fips_enabled || !crypto_has_ahash("sha1", 0, CRYPTO_ALG_ASYNC))
664 return -ENODEV;
665
666 sha_pad = kmalloc(sizeof(struct sha_pad), GFP_KERNEL);
667 if (!sha_pad)
668 return -ENOMEM;
669 sha_pad_init(sha_pad);
670
671 answer = ppp_register_compressor(&ppp_mppe);
672
673 if (answer == 0)
674 printk(KERN_INFO "PPP MPPE Compression module registered\n");
675 else
676 kfree(sha_pad);
677
678 return answer;
679}
680
681static void __exit ppp_mppe_cleanup(void)
682{
683 ppp_unregister_compressor(&ppp_mppe);
684 kfree(sha_pad);
685}
686
687module_init(ppp_mppe_init);
688module_exit(ppp_mppe_cleanup);