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Matt Domschb3f9b922005-11-08 09:40:47 -08001/*
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, write to the Free Software
31 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
32 *
33 *
34 * Changelog:
35 * 08/12/05 - Matt Domsch <Matt_Domsch@dell.com>
36 * Only need extra skb padding on transmit, not receive.
37 * 06/18/04 - Matt Domsch <Matt_Domsch@dell.com>, Oleg Makarenko <mole@quadra.ru>
38 * Use Linux kernel 2.6 arc4 and sha1 routines rather than
39 * providing our own.
40 * 2/15/04 - TS: added #include <version.h> and testing for Kernel
41 * version before using
42 * MOD_DEC_USAGE_COUNT/MOD_INC_USAGE_COUNT which are
43 * deprecated in 2.6
44 */
45
Herbert Xuf12cc202006-08-22 20:36:13 +100046#include <linux/err.h>
Matt Domschb3f9b922005-11-08 09:40:47 -080047#include <linux/module.h>
48#include <linux/kernel.h>
49#include <linux/version.h>
50#include <linux/init.h>
51#include <linux/types.h>
52#include <linux/slab.h>
53#include <linux/string.h>
54#include <linux/crypto.h>
55#include <linux/mm.h>
56#include <linux/ppp_defs.h>
57#include <linux/ppp-comp.h>
58#include <asm/scatterlist.h>
59
60#include "ppp_mppe.h"
61
62MODULE_AUTHOR("Frank Cusack <fcusack@fcusack.com>");
63MODULE_DESCRIPTION("Point-to-Point Protocol Microsoft Point-to-Point Encryption support");
64MODULE_LICENSE("Dual BSD/GPL");
65MODULE_ALIAS("ppp-compress-" __stringify(CI_MPPE));
66MODULE_VERSION("1.0.2");
67
Herbert Xu35058682006-08-24 19:10:20 +100068static unsigned int
Matt Domschb3f9b922005-11-08 09:40:47 -080069setup_sg(struct scatterlist *sg, const void *address, unsigned int length)
70{
71 sg[0].page = virt_to_page(address);
72 sg[0].offset = offset_in_page(address);
73 sg[0].length = length;
Herbert Xu35058682006-08-24 19:10:20 +100074 return length;
Matt Domschb3f9b922005-11-08 09:40:47 -080075}
76
77#define SHA1_PAD_SIZE 40
78
79/*
80 * kernel crypto API needs its arguments to be in kmalloc'd memory, not in the module
81 * static data area. That means sha_pad needs to be kmalloc'd.
82 */
83
84struct sha_pad {
85 unsigned char sha_pad1[SHA1_PAD_SIZE];
86 unsigned char sha_pad2[SHA1_PAD_SIZE];
87};
88static struct sha_pad *sha_pad;
89
90static inline void sha_pad_init(struct sha_pad *shapad)
91{
92 memset(shapad->sha_pad1, 0x00, sizeof(shapad->sha_pad1));
93 memset(shapad->sha_pad2, 0xF2, sizeof(shapad->sha_pad2));
94}
95
96/*
97 * State for an MPPE (de)compressor.
98 */
99struct ppp_mppe_state {
Herbert Xuf12cc202006-08-22 20:36:13 +1000100 struct crypto_blkcipher *arc4;
Herbert Xu35058682006-08-24 19:10:20 +1000101 struct crypto_hash *sha1;
Matt Domschb3f9b922005-11-08 09:40:47 -0800102 unsigned char *sha1_digest;
103 unsigned char master_key[MPPE_MAX_KEY_LEN];
104 unsigned char session_key[MPPE_MAX_KEY_LEN];
105 unsigned keylen; /* key length in bytes */
106 /* NB: 128-bit == 16, 40-bit == 8! */
107 /* If we want to support 56-bit, */
108 /* the unit has to change to bits */
109 unsigned char bits; /* MPPE control bits */
110 unsigned ccount; /* 12-bit coherency count (seqno) */
111 unsigned stateful; /* stateful mode flag */
112 int discard; /* stateful mode packet loss flag */
113 int sanity_errors; /* take down LCP if too many */
114 int unit;
115 int debug;
116 struct compstat stats;
117};
118
119/* struct ppp_mppe_state.bits definitions */
120#define MPPE_BIT_A 0x80 /* Encryption table were (re)inititalized */
121#define MPPE_BIT_B 0x40 /* MPPC only (not implemented) */
122#define MPPE_BIT_C 0x20 /* MPPC only (not implemented) */
123#define MPPE_BIT_D 0x10 /* This is an encrypted frame */
124
125#define MPPE_BIT_FLUSHED MPPE_BIT_A
126#define MPPE_BIT_ENCRYPTED MPPE_BIT_D
127
128#define MPPE_BITS(p) ((p)[4] & 0xf0)
129#define MPPE_CCOUNT(p) ((((p)[4] & 0x0f) << 8) + (p)[5])
130#define MPPE_CCOUNT_SPACE 0x1000 /* The size of the ccount space */
131
132#define MPPE_OVHD 2 /* MPPE overhead/packet */
133#define SANITY_MAX 1600 /* Max bogon factor we will tolerate */
134
135/*
136 * Key Derivation, from RFC 3078, RFC 3079.
137 * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
138 */
139static void get_new_key_from_sha(struct ppp_mppe_state * state, unsigned char *InterimKey)
140{
Herbert Xu35058682006-08-24 19:10:20 +1000141 struct hash_desc desc;
Matt Domschb3f9b922005-11-08 09:40:47 -0800142 struct scatterlist sg[4];
Herbert Xu35058682006-08-24 19:10:20 +1000143 unsigned int nbytes;
Matt Domschb3f9b922005-11-08 09:40:47 -0800144
Herbert Xu35058682006-08-24 19:10:20 +1000145 nbytes = setup_sg(&sg[0], state->master_key, state->keylen);
146 nbytes += setup_sg(&sg[1], sha_pad->sha_pad1,
147 sizeof(sha_pad->sha_pad1));
148 nbytes += setup_sg(&sg[2], state->session_key, state->keylen);
149 nbytes += setup_sg(&sg[3], sha_pad->sha_pad2,
150 sizeof(sha_pad->sha_pad2));
Matt Domschb3f9b922005-11-08 09:40:47 -0800151
Herbert Xu35058682006-08-24 19:10:20 +1000152 desc.tfm = state->sha1;
153 desc.flags = 0;
154
155 crypto_hash_digest(&desc, sg, nbytes, state->sha1_digest);
Matt Domschb3f9b922005-11-08 09:40:47 -0800156
157 memcpy(InterimKey, state->sha1_digest, state->keylen);
158}
159
160/*
161 * Perform the MPPE rekey algorithm, from RFC 3078, sec. 7.3.
162 * Well, not what's written there, but rather what they meant.
163 */
164static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
165{
166 unsigned char InterimKey[MPPE_MAX_KEY_LEN];
167 struct scatterlist sg_in[1], sg_out[1];
Herbert Xuf12cc202006-08-22 20:36:13 +1000168 struct blkcipher_desc desc = { .tfm = state->arc4 };
Matt Domschb3f9b922005-11-08 09:40:47 -0800169
170 get_new_key_from_sha(state, InterimKey);
171 if (!initial_key) {
Herbert Xuf12cc202006-08-22 20:36:13 +1000172 crypto_blkcipher_setkey(state->arc4, InterimKey, state->keylen);
Matt Domschb3f9b922005-11-08 09:40:47 -0800173 setup_sg(sg_in, InterimKey, state->keylen);
174 setup_sg(sg_out, state->session_key, state->keylen);
Herbert Xuf12cc202006-08-22 20:36:13 +1000175 if (crypto_blkcipher_encrypt(&desc, sg_out, sg_in,
176 state->keylen) != 0) {
Matt Domschb3f9b922005-11-08 09:40:47 -0800177 printk(KERN_WARNING "mppe_rekey: cipher_encrypt failed\n");
178 }
179 } else {
180 memcpy(state->session_key, InterimKey, state->keylen);
181 }
182 if (state->keylen == 8) {
183 /* See RFC 3078 */
184 state->session_key[0] = 0xd1;
185 state->session_key[1] = 0x26;
186 state->session_key[2] = 0x9e;
187 }
Herbert Xuf12cc202006-08-22 20:36:13 +1000188 crypto_blkcipher_setkey(state->arc4, state->session_key, state->keylen);
Matt Domschb3f9b922005-11-08 09:40:47 -0800189}
190
191/*
192 * Allocate space for a (de)compressor.
193 */
194static void *mppe_alloc(unsigned char *options, int optlen)
195{
196 struct ppp_mppe_state *state;
197 unsigned int digestsize;
198
199 if (optlen != CILEN_MPPE + sizeof(state->master_key)
200 || options[0] != CI_MPPE || options[1] != CILEN_MPPE)
201 goto out;
202
Robert P. J. Day5cbded52006-12-13 00:35:56 -0800203 state = kmalloc(sizeof(*state), GFP_KERNEL);
Matt Domschb3f9b922005-11-08 09:40:47 -0800204 if (state == NULL)
205 goto out;
206
207 memset(state, 0, sizeof(*state));
208
Herbert Xuf12cc202006-08-22 20:36:13 +1000209 state->arc4 = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
210 if (IS_ERR(state->arc4)) {
211 state->arc4 = NULL;
Matt Domschb3f9b922005-11-08 09:40:47 -0800212 goto out_free;
Herbert Xuf12cc202006-08-22 20:36:13 +1000213 }
Matt Domschb3f9b922005-11-08 09:40:47 -0800214
Herbert Xu35058682006-08-24 19:10:20 +1000215 state->sha1 = crypto_alloc_hash("sha1", 0, CRYPTO_ALG_ASYNC);
216 if (IS_ERR(state->sha1)) {
217 state->sha1 = NULL;
Matt Domschb3f9b922005-11-08 09:40:47 -0800218 goto out_free;
Herbert Xu35058682006-08-24 19:10:20 +1000219 }
Matt Domschb3f9b922005-11-08 09:40:47 -0800220
Herbert Xu35058682006-08-24 19:10:20 +1000221 digestsize = crypto_hash_digestsize(state->sha1);
Matt Domschb3f9b922005-11-08 09:40:47 -0800222 if (digestsize < MPPE_MAX_KEY_LEN)
223 goto out_free;
224
225 state->sha1_digest = kmalloc(digestsize, GFP_KERNEL);
226 if (!state->sha1_digest)
227 goto out_free;
228
229 /* Save keys. */
230 memcpy(state->master_key, &options[CILEN_MPPE],
231 sizeof(state->master_key));
232 memcpy(state->session_key, state->master_key,
233 sizeof(state->master_key));
234
235 /*
236 * We defer initial key generation until mppe_init(), as mppe_alloc()
237 * is called frequently during negotiation.
238 */
239
240 return (void *)state;
241
242 out_free:
243 if (state->sha1_digest)
244 kfree(state->sha1_digest);
245 if (state->sha1)
Herbert Xu35058682006-08-24 19:10:20 +1000246 crypto_free_hash(state->sha1);
Matt Domschb3f9b922005-11-08 09:40:47 -0800247 if (state->arc4)
Herbert Xuf12cc202006-08-22 20:36:13 +1000248 crypto_free_blkcipher(state->arc4);
Matt Domschb3f9b922005-11-08 09:40:47 -0800249 kfree(state);
250 out:
251 return NULL;
252}
253
254/*
255 * Deallocate space for a (de)compressor.
256 */
257static void mppe_free(void *arg)
258{
259 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
260 if (state) {
261 if (state->sha1_digest)
262 kfree(state->sha1_digest);
263 if (state->sha1)
Herbert Xu35058682006-08-24 19:10:20 +1000264 crypto_free_hash(state->sha1);
Matt Domschb3f9b922005-11-08 09:40:47 -0800265 if (state->arc4)
Herbert Xuf12cc202006-08-22 20:36:13 +1000266 crypto_free_blkcipher(state->arc4);
Matt Domschb3f9b922005-11-08 09:40:47 -0800267 kfree(state);
268 }
269}
270
271/*
272 * Initialize (de)compressor state.
273 */
274static int
275mppe_init(void *arg, unsigned char *options, int optlen, int unit, int debug,
276 const char *debugstr)
277{
278 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
279 unsigned char mppe_opts;
280
281 if (optlen != CILEN_MPPE
282 || options[0] != CI_MPPE || options[1] != CILEN_MPPE)
283 return 0;
284
285 MPPE_CI_TO_OPTS(&options[2], mppe_opts);
286 if (mppe_opts & MPPE_OPT_128)
287 state->keylen = 16;
288 else if (mppe_opts & MPPE_OPT_40)
289 state->keylen = 8;
290 else {
291 printk(KERN_WARNING "%s[%d]: unknown key length\n", debugstr,
292 unit);
293 return 0;
294 }
295 if (mppe_opts & MPPE_OPT_STATEFUL)
296 state->stateful = 1;
297
298 /* Generate the initial session key. */
299 mppe_rekey(state, 1);
300
301 if (debug) {
302 int i;
303 char mkey[sizeof(state->master_key) * 2 + 1];
304 char skey[sizeof(state->session_key) * 2 + 1];
305
306 printk(KERN_DEBUG "%s[%d]: initialized with %d-bit %s mode\n",
307 debugstr, unit, (state->keylen == 16) ? 128 : 40,
308 (state->stateful) ? "stateful" : "stateless");
309
310 for (i = 0; i < sizeof(state->master_key); i++)
311 sprintf(mkey + i * 2, "%02x", state->master_key[i]);
312 for (i = 0; i < sizeof(state->session_key); i++)
313 sprintf(skey + i * 2, "%02x", state->session_key[i]);
314 printk(KERN_DEBUG
315 "%s[%d]: keys: master: %s initial session: %s\n",
316 debugstr, unit, mkey, skey);
317 }
318
319 /*
320 * Initialize the coherency count. The initial value is not specified
321 * in RFC 3078, but we can make a reasonable assumption that it will
322 * start at 0. Setting it to the max here makes the comp/decomp code
323 * do the right thing (determined through experiment).
324 */
325 state->ccount = MPPE_CCOUNT_SPACE - 1;
326
327 /*
328 * Note that even though we have initialized the key table, we don't
329 * set the FLUSHED bit. This is contrary to RFC 3078, sec. 3.1.
330 */
331 state->bits = MPPE_BIT_ENCRYPTED;
332
333 state->unit = unit;
334 state->debug = debug;
335
336 return 1;
337}
338
339static int
340mppe_comp_init(void *arg, unsigned char *options, int optlen, int unit,
341 int hdrlen, int debug)
342{
343 /* ARGSUSED */
344 return mppe_init(arg, options, optlen, unit, debug, "mppe_comp_init");
345}
346
347/*
348 * We received a CCP Reset-Request (actually, we are sending a Reset-Ack),
349 * tell the compressor to rekey. Note that we MUST NOT rekey for
350 * every CCP Reset-Request; we only rekey on the next xmit packet.
351 * We might get multiple CCP Reset-Requests if our CCP Reset-Ack is lost.
352 * So, rekeying for every CCP Reset-Request is broken as the peer will not
353 * know how many times we've rekeyed. (If we rekey and THEN get another
354 * CCP Reset-Request, we must rekey again.)
355 */
356static void mppe_comp_reset(void *arg)
357{
358 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
359
360 state->bits |= MPPE_BIT_FLUSHED;
361}
362
363/*
364 * Compress (encrypt) a packet.
365 * It's strange to call this a compressor, since the output is always
366 * MPPE_OVHD + 2 bytes larger than the input.
367 */
368static int
369mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf,
370 int isize, int osize)
371{
372 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
Herbert Xuf12cc202006-08-22 20:36:13 +1000373 struct blkcipher_desc desc = { .tfm = state->arc4 };
Matt Domschb3f9b922005-11-08 09:40:47 -0800374 int proto;
375 struct scatterlist sg_in[1], sg_out[1];
376
377 /*
378 * Check that the protocol is in the range we handle.
379 */
380 proto = PPP_PROTOCOL(ibuf);
381 if (proto < 0x0021 || proto > 0x00fa)
382 return 0;
383
384 /* Make sure we have enough room to generate an encrypted packet. */
385 if (osize < isize + MPPE_OVHD + 2) {
386 /* Drop the packet if we should encrypt it, but can't. */
387 printk(KERN_DEBUG "mppe_compress[%d]: osize too small! "
388 "(have: %d need: %d)\n", state->unit,
389 osize, osize + MPPE_OVHD + 2);
390 return -1;
391 }
392
393 osize = isize + MPPE_OVHD + 2;
394
395 /*
396 * Copy over the PPP header and set control bits.
397 */
398 obuf[0] = PPP_ADDRESS(ibuf);
399 obuf[1] = PPP_CONTROL(ibuf);
400 obuf[2] = PPP_COMP >> 8; /* isize + MPPE_OVHD + 1 */
401 obuf[3] = PPP_COMP; /* isize + MPPE_OVHD + 2 */
402 obuf += PPP_HDRLEN;
403
404 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
405 if (state->debug >= 7)
406 printk(KERN_DEBUG "mppe_compress[%d]: ccount %d\n", state->unit,
407 state->ccount);
408 obuf[0] = state->ccount >> 8;
409 obuf[1] = state->ccount & 0xff;
410
411 if (!state->stateful || /* stateless mode */
412 ((state->ccount & 0xff) == 0xff) || /* "flag" packet */
413 (state->bits & MPPE_BIT_FLUSHED)) { /* CCP Reset-Request */
414 /* We must rekey */
415 if (state->debug && state->stateful)
416 printk(KERN_DEBUG "mppe_compress[%d]: rekeying\n",
417 state->unit);
418 mppe_rekey(state, 0);
419 state->bits |= MPPE_BIT_FLUSHED;
420 }
421 obuf[0] |= state->bits;
422 state->bits &= ~MPPE_BIT_FLUSHED; /* reset for next xmit */
423
424 obuf += MPPE_OVHD;
425 ibuf += 2; /* skip to proto field */
426 isize -= 2;
427
428 /* Encrypt packet */
429 setup_sg(sg_in, ibuf, isize);
430 setup_sg(sg_out, obuf, osize);
Herbert Xuf12cc202006-08-22 20:36:13 +1000431 if (crypto_blkcipher_encrypt(&desc, sg_out, sg_in, isize) != 0) {
Matt Domschb3f9b922005-11-08 09:40:47 -0800432 printk(KERN_DEBUG "crypto_cypher_encrypt failed\n");
433 return -1;
434 }
435
436 state->stats.unc_bytes += isize;
437 state->stats.unc_packets++;
438 state->stats.comp_bytes += osize;
439 state->stats.comp_packets++;
440
441 return osize;
442}
443
444/*
445 * Since every frame grows by MPPE_OVHD + 2 bytes, this is always going
446 * to look bad ... and the longer the link is up the worse it will get.
447 */
448static void mppe_comp_stats(void *arg, struct compstat *stats)
449{
450 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
451
452 *stats = state->stats;
453}
454
455static int
456mppe_decomp_init(void *arg, unsigned char *options, int optlen, int unit,
457 int hdrlen, int mru, int debug)
458{
459 /* ARGSUSED */
460 return mppe_init(arg, options, optlen, unit, debug, "mppe_decomp_init");
461}
462
463/*
464 * We received a CCP Reset-Ack. Just ignore it.
465 */
466static void mppe_decomp_reset(void *arg)
467{
468 /* ARGSUSED */
469 return;
470}
471
472/*
473 * Decompress (decrypt) an MPPE packet.
474 */
475static int
476mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
477 int osize)
478{
479 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
Herbert Xuf12cc202006-08-22 20:36:13 +1000480 struct blkcipher_desc desc = { .tfm = state->arc4 };
Matt Domschb3f9b922005-11-08 09:40:47 -0800481 unsigned ccount;
482 int flushed = MPPE_BITS(ibuf) & MPPE_BIT_FLUSHED;
483 int sanity = 0;
484 struct scatterlist sg_in[1], sg_out[1];
485
486 if (isize <= PPP_HDRLEN + MPPE_OVHD) {
487 if (state->debug)
488 printk(KERN_DEBUG
489 "mppe_decompress[%d]: short pkt (%d)\n",
490 state->unit, isize);
491 return DECOMP_ERROR;
492 }
493
494 /*
495 * Make sure we have enough room to decrypt the packet.
496 * Note that for our test we only subtract 1 byte whereas in
497 * mppe_compress() we added 2 bytes (+MPPE_OVHD);
498 * this is to account for possible PFC.
499 */
500 if (osize < isize - MPPE_OVHD - 1) {
501 printk(KERN_DEBUG "mppe_decompress[%d]: osize too small! "
502 "(have: %d need: %d)\n", state->unit,
503 osize, isize - MPPE_OVHD - 1);
504 return DECOMP_ERROR;
505 }
506 osize = isize - MPPE_OVHD - 2; /* assume no PFC */
507
508 ccount = MPPE_CCOUNT(ibuf);
509 if (state->debug >= 7)
510 printk(KERN_DEBUG "mppe_decompress[%d]: ccount %d\n",
511 state->unit, ccount);
512
513 /* sanity checks -- terminate with extreme prejudice */
514 if (!(MPPE_BITS(ibuf) & MPPE_BIT_ENCRYPTED)) {
515 printk(KERN_DEBUG
516 "mppe_decompress[%d]: ENCRYPTED bit not set!\n",
517 state->unit);
518 state->sanity_errors += 100;
519 sanity = 1;
520 }
521 if (!state->stateful && !flushed) {
522 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set in "
523 "stateless mode!\n", state->unit);
524 state->sanity_errors += 100;
525 sanity = 1;
526 }
527 if (state->stateful && ((ccount & 0xff) == 0xff) && !flushed) {
528 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set on "
529 "flag packet!\n", state->unit);
530 state->sanity_errors += 100;
531 sanity = 1;
532 }
533
534 if (sanity) {
535 if (state->sanity_errors < SANITY_MAX)
536 return DECOMP_ERROR;
537 else
538 /*
539 * Take LCP down if the peer is sending too many bogons.
540 * We don't want to do this for a single or just a few
541 * instances since it could just be due to packet corruption.
542 */
543 return DECOMP_FATALERROR;
544 }
545
546 /*
547 * Check the coherency count.
548 */
549
550 if (!state->stateful) {
551 /* RFC 3078, sec 8.1. Rekey for every packet. */
552 while (state->ccount != ccount) {
553 mppe_rekey(state, 0);
554 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
555 }
556 } else {
557 /* RFC 3078, sec 8.2. */
558 if (!state->discard) {
559 /* normal state */
560 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
561 if (ccount != state->ccount) {
562 /*
563 * (ccount > state->ccount)
564 * Packet loss detected, enter the discard state.
565 * Signal the peer to rekey (by sending a CCP Reset-Request).
566 */
567 state->discard = 1;
568 return DECOMP_ERROR;
569 }
570 } else {
571 /* discard state */
572 if (!flushed) {
573 /* ccp.c will be silent (no additional CCP Reset-Requests). */
574 return DECOMP_ERROR;
575 } else {
576 /* Rekey for every missed "flag" packet. */
577 while ((ccount & ~0xff) !=
578 (state->ccount & ~0xff)) {
579 mppe_rekey(state, 0);
580 state->ccount =
581 (state->ccount +
582 256) % MPPE_CCOUNT_SPACE;
583 }
584
585 /* reset */
586 state->discard = 0;
587 state->ccount = ccount;
588 /*
589 * Another problem with RFC 3078 here. It implies that the
590 * peer need not send a Reset-Ack packet. But RFC 1962
591 * requires it. Hopefully, M$ does send a Reset-Ack; even
592 * though it isn't required for MPPE synchronization, it is
593 * required to reset CCP state.
594 */
595 }
596 }
597 if (flushed)
598 mppe_rekey(state, 0);
599 }
600
601 /*
602 * Fill in the first part of the PPP header. The protocol field
603 * comes from the decrypted data.
604 */
605 obuf[0] = PPP_ADDRESS(ibuf); /* +1 */
606 obuf[1] = PPP_CONTROL(ibuf); /* +1 */
607 obuf += 2;
608 ibuf += PPP_HDRLEN + MPPE_OVHD;
609 isize -= PPP_HDRLEN + MPPE_OVHD; /* -6 */
610 /* net osize: isize-4 */
611
612 /*
613 * Decrypt the first byte in order to check if it is
614 * a compressed or uncompressed protocol field.
615 */
616 setup_sg(sg_in, ibuf, 1);
617 setup_sg(sg_out, obuf, 1);
Herbert Xuf12cc202006-08-22 20:36:13 +1000618 if (crypto_blkcipher_decrypt(&desc, sg_out, sg_in, 1) != 0) {
Matt Domschb3f9b922005-11-08 09:40:47 -0800619 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);
Herbert Xuf12cc202006-08-22 20:36:13 +1000638 if (crypto_blkcipher_decrypt(&desc, sg_out, sg_in, isize - 1)) {
Matt Domschb3f9b922005-11-08 09:40:47 -0800639 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;
Herbert Xue4d5b792006-08-26 18:12:40 +1000713 if (!(crypto_has_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC) &&
714 crypto_has_hash("sha1", 0, CRYPTO_ALG_ASYNC)))
Matt Domschb3f9b922005-11-08 09:40:47 -0800715 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);