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/hash.h>
46 #include <crypto/skcipher.h>
47 #include <linux/err.h>
48 #include <linux/module.h>
49 #include <linux/kernel.h>
50 #include <linux/init.h>
51 #include <linux/types.h>
52 #include <linux/slab.h>
53 #include <linux/string.h>
54 #include <linux/mm.h>
55 #include <linux/ppp_defs.h>
56 #include <linux/ppp-comp.h>
57 #include <linux/scatterlist.h>
58 #include <asm/unaligned.h>
59
60 #include "ppp_mppe.h"
61
62 MODULE_AUTHOR("Frank Cusack <fcusack@fcusack.com>");
63 MODULE_DESCRIPTION("Point-to-Point Protocol Microsoft Point-to-Point Encryption support");
64 MODULE_LICENSE("Dual BSD/GPL");
65 MODULE_ALIAS("ppp-compress-" __stringify(CI_MPPE));
66 MODULE_SOFTDEP("pre: arc4");
67 MODULE_VERSION("1.0.2");
68
69 static unsigned int
setup_sg(struct scatterlist * sg,const void * address,unsigned int length)70 setup_sg(struct scatterlist *sg, const void *address, unsigned int length)
71 {
72 sg_set_buf(sg, address, length);
73 return length;
74 }
75
76 #define SHA1_PAD_SIZE 40
77
78 /*
79 * kernel crypto API needs its arguments to be in kmalloc'd memory, not in the module
80 * static data area. That means sha_pad needs to be kmalloc'd.
81 */
82
83 struct sha_pad {
84 unsigned char sha_pad1[SHA1_PAD_SIZE];
85 unsigned char sha_pad2[SHA1_PAD_SIZE];
86 };
87 static struct sha_pad *sha_pad;
88
sha_pad_init(struct sha_pad * shapad)89 static inline void sha_pad_init(struct sha_pad *shapad)
90 {
91 memset(shapad->sha_pad1, 0x00, sizeof(shapad->sha_pad1));
92 memset(shapad->sha_pad2, 0xF2, sizeof(shapad->sha_pad2));
93 }
94
95 /*
96 * State for an MPPE (de)compressor.
97 */
98 struct ppp_mppe_state {
99 struct crypto_skcipher *arc4;
100 struct crypto_ahash *sha1;
101 unsigned char *sha1_digest;
102 unsigned char master_key[MPPE_MAX_KEY_LEN];
103 unsigned char session_key[MPPE_MAX_KEY_LEN];
104 unsigned keylen; /* key length in bytes */
105 /* NB: 128-bit == 16, 40-bit == 8! */
106 /* If we want to support 56-bit, */
107 /* the unit has to change to bits */
108 unsigned char bits; /* MPPE control bits */
109 unsigned ccount; /* 12-bit coherency count (seqno) */
110 unsigned stateful; /* stateful mode flag */
111 int discard; /* stateful mode packet loss flag */
112 int sanity_errors; /* take down LCP if too many */
113 int unit;
114 int debug;
115 struct compstat stats;
116 };
117
118 /* struct ppp_mppe_state.bits definitions */
119 #define MPPE_BIT_A 0x80 /* Encryption table were (re)inititalized */
120 #define MPPE_BIT_B 0x40 /* MPPC only (not implemented) */
121 #define MPPE_BIT_C 0x20 /* MPPC only (not implemented) */
122 #define MPPE_BIT_D 0x10 /* This is an encrypted frame */
123
124 #define MPPE_BIT_FLUSHED MPPE_BIT_A
125 #define MPPE_BIT_ENCRYPTED MPPE_BIT_D
126
127 #define MPPE_BITS(p) ((p)[4] & 0xf0)
128 #define MPPE_CCOUNT(p) ((((p)[4] & 0x0f) << 8) + (p)[5])
129 #define MPPE_CCOUNT_SPACE 0x1000 /* The size of the ccount space */
130
131 #define MPPE_OVHD 2 /* MPPE overhead/packet */
132 #define SANITY_MAX 1600 /* Max bogon factor we will tolerate */
133
134 /*
135 * Key Derivation, from RFC 3078, RFC 3079.
136 * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
137 */
get_new_key_from_sha(struct ppp_mppe_state * state)138 static void get_new_key_from_sha(struct ppp_mppe_state * state)
139 {
140 AHASH_REQUEST_ON_STACK(req, state->sha1);
141 struct scatterlist sg[4];
142 unsigned int nbytes;
143
144 sg_init_table(sg, 4);
145
146 nbytes = setup_sg(&sg[0], state->master_key, state->keylen);
147 nbytes += setup_sg(&sg[1], sha_pad->sha_pad1,
148 sizeof(sha_pad->sha_pad1));
149 nbytes += setup_sg(&sg[2], state->session_key, state->keylen);
150 nbytes += setup_sg(&sg[3], sha_pad->sha_pad2,
151 sizeof(sha_pad->sha_pad2));
152
153 ahash_request_set_tfm(req, state->sha1);
154 ahash_request_set_callback(req, 0, NULL, NULL);
155 ahash_request_set_crypt(req, sg, state->sha1_digest, nbytes);
156
157 crypto_ahash_digest(req);
158 ahash_request_zero(req);
159 }
160
161 /*
162 * Perform the MPPE rekey algorithm, from RFC 3078, sec. 7.3.
163 * Well, not what's written there, but rather what they meant.
164 */
mppe_rekey(struct ppp_mppe_state * state,int initial_key)165 static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
166 {
167 struct scatterlist sg_in[1], sg_out[1];
168 SKCIPHER_REQUEST_ON_STACK(req, state->arc4);
169
170 skcipher_request_set_tfm(req, state->arc4);
171 skcipher_request_set_callback(req, 0, NULL, NULL);
172
173 get_new_key_from_sha(state);
174 if (!initial_key) {
175 crypto_skcipher_setkey(state->arc4, state->sha1_digest,
176 state->keylen);
177 sg_init_table(sg_in, 1);
178 sg_init_table(sg_out, 1);
179 setup_sg(sg_in, state->sha1_digest, state->keylen);
180 setup_sg(sg_out, state->session_key, state->keylen);
181 skcipher_request_set_crypt(req, sg_in, sg_out, state->keylen,
182 NULL);
183 if (crypto_skcipher_encrypt(req))
184 printk(KERN_WARNING "mppe_rekey: cipher_encrypt failed\n");
185 } else {
186 memcpy(state->session_key, state->sha1_digest, state->keylen);
187 }
188 if (state->keylen == 8) {
189 /* See RFC 3078 */
190 state->session_key[0] = 0xd1;
191 state->session_key[1] = 0x26;
192 state->session_key[2] = 0x9e;
193 }
194 crypto_skcipher_setkey(state->arc4, state->session_key, state->keylen);
195 skcipher_request_zero(req);
196 }
197
198 /*
199 * Allocate space for a (de)compressor.
200 */
mppe_alloc(unsigned char * options,int optlen)201 static void *mppe_alloc(unsigned char *options, int optlen)
202 {
203 struct ppp_mppe_state *state;
204 unsigned int digestsize;
205
206 if (optlen != CILEN_MPPE + sizeof(state->master_key) ||
207 options[0] != CI_MPPE || options[1] != CILEN_MPPE)
208 goto out;
209
210 state = kzalloc(sizeof(*state), GFP_KERNEL);
211 if (state == NULL)
212 goto out;
213
214
215 state->arc4 = crypto_alloc_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC);
216 if (IS_ERR(state->arc4)) {
217 state->arc4 = NULL;
218 goto out_free;
219 }
220
221 state->sha1 = crypto_alloc_ahash("sha1", 0, CRYPTO_ALG_ASYNC);
222 if (IS_ERR(state->sha1)) {
223 state->sha1 = NULL;
224 goto out_free;
225 }
226
227 digestsize = crypto_ahash_digestsize(state->sha1);
228 if (digestsize < MPPE_MAX_KEY_LEN)
229 goto out_free;
230
231 state->sha1_digest = kmalloc(digestsize, GFP_KERNEL);
232 if (!state->sha1_digest)
233 goto out_free;
234
235 /* Save keys. */
236 memcpy(state->master_key, &options[CILEN_MPPE],
237 sizeof(state->master_key));
238 memcpy(state->session_key, state->master_key,
239 sizeof(state->master_key));
240
241 /*
242 * We defer initial key generation until mppe_init(), as mppe_alloc()
243 * is called frequently during negotiation.
244 */
245
246 return (void *)state;
247
248 out_free:
249 kfree(state->sha1_digest);
250 crypto_free_ahash(state->sha1);
251 crypto_free_skcipher(state->arc4);
252 kfree(state);
253 out:
254 return NULL;
255 }
256
257 /*
258 * Deallocate space for a (de)compressor.
259 */
mppe_free(void * arg)260 static void mppe_free(void *arg)
261 {
262 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
263 if (state) {
264 kfree(state->sha1_digest);
265 crypto_free_ahash(state->sha1);
266 crypto_free_skcipher(state->arc4);
267 kfree(state);
268 }
269 }
270
271 /*
272 * Initialize (de)compressor state.
273 */
274 static int
mppe_init(void * arg,unsigned char * options,int optlen,int unit,int debug,const char * debugstr)275 mppe_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 printk(KERN_DEBUG "%s[%d]: initialized with %d-bit %s mode\n",
303 debugstr, unit, (state->keylen == 16) ? 128 : 40,
304 (state->stateful) ? "stateful" : "stateless");
305 printk(KERN_DEBUG
306 "%s[%d]: keys: master: %*phN initial session: %*phN\n",
307 debugstr, unit,
308 (int)sizeof(state->master_key), state->master_key,
309 (int)sizeof(state->session_key), state->session_key);
310 }
311
312 /*
313 * Initialize the coherency count. The initial value is not specified
314 * in RFC 3078, but we can make a reasonable assumption that it will
315 * start at 0. Setting it to the max here makes the comp/decomp code
316 * do the right thing (determined through experiment).
317 */
318 state->ccount = MPPE_CCOUNT_SPACE - 1;
319
320 /*
321 * Note that even though we have initialized the key table, we don't
322 * set the FLUSHED bit. This is contrary to RFC 3078, sec. 3.1.
323 */
324 state->bits = MPPE_BIT_ENCRYPTED;
325
326 state->unit = unit;
327 state->debug = debug;
328
329 return 1;
330 }
331
332 static int
mppe_comp_init(void * arg,unsigned char * options,int optlen,int unit,int hdrlen,int debug)333 mppe_comp_init(void *arg, unsigned char *options, int optlen, int unit,
334 int hdrlen, int debug)
335 {
336 /* ARGSUSED */
337 return mppe_init(arg, options, optlen, unit, debug, "mppe_comp_init");
338 }
339
340 /*
341 * We received a CCP Reset-Request (actually, we are sending a Reset-Ack),
342 * tell the compressor to rekey. Note that we MUST NOT rekey for
343 * every CCP Reset-Request; we only rekey on the next xmit packet.
344 * We might get multiple CCP Reset-Requests if our CCP Reset-Ack is lost.
345 * So, rekeying for every CCP Reset-Request is broken as the peer will not
346 * know how many times we've rekeyed. (If we rekey and THEN get another
347 * CCP Reset-Request, we must rekey again.)
348 */
mppe_comp_reset(void * arg)349 static void mppe_comp_reset(void *arg)
350 {
351 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
352
353 state->bits |= MPPE_BIT_FLUSHED;
354 }
355
356 /*
357 * Compress (encrypt) a packet.
358 * It's strange to call this a compressor, since the output is always
359 * MPPE_OVHD + 2 bytes larger than the input.
360 */
361 static int
mppe_compress(void * arg,unsigned char * ibuf,unsigned char * obuf,int isize,int osize)362 mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf,
363 int isize, int osize)
364 {
365 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
366 SKCIPHER_REQUEST_ON_STACK(req, state->arc4);
367 int proto;
368 int err;
369 struct scatterlist sg_in[1], sg_out[1];
370
371 /*
372 * Check that the protocol is in the range we handle.
373 */
374 proto = PPP_PROTOCOL(ibuf);
375 if (proto < 0x0021 || proto > 0x00fa)
376 return 0;
377
378 /* Make sure we have enough room to generate an encrypted packet. */
379 if (osize < isize + MPPE_OVHD + 2) {
380 /* Drop the packet if we should encrypt it, but can't. */
381 printk(KERN_DEBUG "mppe_compress[%d]: osize too small! "
382 "(have: %d need: %d)\n", state->unit,
383 osize, osize + MPPE_OVHD + 2);
384 return -1;
385 }
386
387 osize = isize + MPPE_OVHD + 2;
388
389 /*
390 * Copy over the PPP header and set control bits.
391 */
392 obuf[0] = PPP_ADDRESS(ibuf);
393 obuf[1] = PPP_CONTROL(ibuf);
394 put_unaligned_be16(PPP_COMP, obuf + 2);
395 obuf += PPP_HDRLEN;
396
397 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
398 if (state->debug >= 7)
399 printk(KERN_DEBUG "mppe_compress[%d]: ccount %d\n", state->unit,
400 state->ccount);
401 put_unaligned_be16(state->ccount, obuf);
402
403 if (!state->stateful || /* stateless mode */
404 ((state->ccount & 0xff) == 0xff) || /* "flag" packet */
405 (state->bits & MPPE_BIT_FLUSHED)) { /* CCP Reset-Request */
406 /* We must rekey */
407 if (state->debug && state->stateful)
408 printk(KERN_DEBUG "mppe_compress[%d]: rekeying\n",
409 state->unit);
410 mppe_rekey(state, 0);
411 state->bits |= MPPE_BIT_FLUSHED;
412 }
413 obuf[0] |= state->bits;
414 state->bits &= ~MPPE_BIT_FLUSHED; /* reset for next xmit */
415
416 obuf += MPPE_OVHD;
417 ibuf += 2; /* skip to proto field */
418 isize -= 2;
419
420 /* Encrypt packet */
421 sg_init_table(sg_in, 1);
422 sg_init_table(sg_out, 1);
423 setup_sg(sg_in, ibuf, isize);
424 setup_sg(sg_out, obuf, osize);
425
426 skcipher_request_set_tfm(req, state->arc4);
427 skcipher_request_set_callback(req, 0, NULL, NULL);
428 skcipher_request_set_crypt(req, sg_in, sg_out, isize, NULL);
429 err = crypto_skcipher_encrypt(req);
430 skcipher_request_zero(req);
431 if (err) {
432 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 */
mppe_comp_stats(void * arg,struct compstat * stats)448 static 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
455 static int
mppe_decomp_init(void * arg,unsigned char * options,int optlen,int unit,int hdrlen,int mru,int debug)456 mppe_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 */
mppe_decomp_reset(void * arg)466 static void mppe_decomp_reset(void *arg)
467 {
468 /* ARGSUSED */
469 return;
470 }
471
472 /*
473 * Decompress (decrypt) an MPPE packet.
474 */
475 static int
mppe_decompress(void * arg,unsigned char * ibuf,int isize,unsigned char * obuf,int osize)476 mppe_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;
480 SKCIPHER_REQUEST_ON_STACK(req, state->arc4);
481 unsigned ccount;
482 int flushed = MPPE_BITS(ibuf) & MPPE_BIT_FLUSHED;
483 struct scatterlist sg_in[1], sg_out[1];
484
485 if (isize <= PPP_HDRLEN + MPPE_OVHD) {
486 if (state->debug)
487 printk(KERN_DEBUG
488 "mppe_decompress[%d]: short pkt (%d)\n",
489 state->unit, isize);
490 return DECOMP_ERROR;
491 }
492
493 /*
494 * Make sure we have enough room to decrypt the packet.
495 * Note that for our test we only subtract 1 byte whereas in
496 * mppe_compress() we added 2 bytes (+MPPE_OVHD);
497 * this is to account for possible PFC.
498 */
499 if (osize < isize - MPPE_OVHD - 1) {
500 printk(KERN_DEBUG "mppe_decompress[%d]: osize too small! "
501 "(have: %d need: %d)\n", state->unit,
502 osize, isize - MPPE_OVHD - 1);
503 return DECOMP_ERROR;
504 }
505 osize = isize - MPPE_OVHD - 2; /* assume no PFC */
506
507 ccount = MPPE_CCOUNT(ibuf);
508 if (state->debug >= 7)
509 printk(KERN_DEBUG "mppe_decompress[%d]: ccount %d\n",
510 state->unit, ccount);
511
512 /* sanity checks -- terminate with extreme prejudice */
513 if (!(MPPE_BITS(ibuf) & MPPE_BIT_ENCRYPTED)) {
514 printk(KERN_DEBUG
515 "mppe_decompress[%d]: ENCRYPTED bit not set!\n",
516 state->unit);
517 state->sanity_errors += 100;
518 goto sanity_error;
519 }
520 if (!state->stateful && !flushed) {
521 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set in "
522 "stateless mode!\n", state->unit);
523 state->sanity_errors += 100;
524 goto sanity_error;
525 }
526 if (state->stateful && ((ccount & 0xff) == 0xff) && !flushed) {
527 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set on "
528 "flag packet!\n", state->unit);
529 state->sanity_errors += 100;
530 goto sanity_error;
531 }
532
533 /*
534 * Check the coherency count.
535 */
536
537 if (!state->stateful) {
538 /* Discard late packet */
539 if ((ccount - state->ccount) % MPPE_CCOUNT_SPACE
540 > MPPE_CCOUNT_SPACE / 2) {
541 state->sanity_errors++;
542 goto sanity_error;
543 }
544
545 /* RFC 3078, sec 8.1. Rekey for every packet. */
546 while (state->ccount != ccount) {
547 mppe_rekey(state, 0);
548 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
549 }
550 } else {
551 /* RFC 3078, sec 8.2. */
552 if (!state->discard) {
553 /* normal state */
554 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
555 if (ccount != state->ccount) {
556 /*
557 * (ccount > state->ccount)
558 * Packet loss detected, enter the discard state.
559 * Signal the peer to rekey (by sending a CCP Reset-Request).
560 */
561 state->discard = 1;
562 return DECOMP_ERROR;
563 }
564 } else {
565 /* discard state */
566 if (!flushed) {
567 /* ccp.c will be silent (no additional CCP Reset-Requests). */
568 return DECOMP_ERROR;
569 } else {
570 /* Rekey for every missed "flag" packet. */
571 while ((ccount & ~0xff) !=
572 (state->ccount & ~0xff)) {
573 mppe_rekey(state, 0);
574 state->ccount =
575 (state->ccount +
576 256) % MPPE_CCOUNT_SPACE;
577 }
578
579 /* reset */
580 state->discard = 0;
581 state->ccount = ccount;
582 /*
583 * Another problem with RFC 3078 here. It implies that the
584 * peer need not send a Reset-Ack packet. But RFC 1962
585 * requires it. Hopefully, M$ does send a Reset-Ack; even
586 * though it isn't required for MPPE synchronization, it is
587 * required to reset CCP state.
588 */
589 }
590 }
591 if (flushed)
592 mppe_rekey(state, 0);
593 }
594
595 /*
596 * Fill in the first part of the PPP header. The protocol field
597 * comes from the decrypted data.
598 */
599 obuf[0] = PPP_ADDRESS(ibuf); /* +1 */
600 obuf[1] = PPP_CONTROL(ibuf); /* +1 */
601 obuf += 2;
602 ibuf += PPP_HDRLEN + MPPE_OVHD;
603 isize -= PPP_HDRLEN + MPPE_OVHD; /* -6 */
604 /* net osize: isize-4 */
605
606 /*
607 * Decrypt the first byte in order to check if it is
608 * a compressed or uncompressed protocol field.
609 */
610 sg_init_table(sg_in, 1);
611 sg_init_table(sg_out, 1);
612 setup_sg(sg_in, ibuf, 1);
613 setup_sg(sg_out, obuf, 1);
614
615 skcipher_request_set_tfm(req, state->arc4);
616 skcipher_request_set_callback(req, 0, NULL, NULL);
617 skcipher_request_set_crypt(req, sg_in, sg_out, 1, NULL);
618 if (crypto_skcipher_decrypt(req)) {
619 printk(KERN_DEBUG "crypto_cypher_decrypt failed\n");
620 osize = DECOMP_ERROR;
621 goto out_zap_req;
622 }
623
624 /*
625 * Do PFC decompression.
626 * This would be nicer if we were given the actual sk_buff
627 * instead of a char *.
628 */
629 if ((obuf[0] & 0x01) != 0) {
630 obuf[1] = obuf[0];
631 obuf[0] = 0;
632 obuf++;
633 osize++;
634 }
635
636 /* And finally, decrypt the rest of the packet. */
637 setup_sg(sg_in, ibuf + 1, isize - 1);
638 setup_sg(sg_out, obuf + 1, osize - 1);
639 skcipher_request_set_crypt(req, sg_in, sg_out, isize - 1, NULL);
640 if (crypto_skcipher_decrypt(req)) {
641 printk(KERN_DEBUG "crypto_cypher_decrypt failed\n");
642 osize = DECOMP_ERROR;
643 goto out_zap_req;
644 }
645
646 state->stats.unc_bytes += osize;
647 state->stats.unc_packets++;
648 state->stats.comp_bytes += isize;
649 state->stats.comp_packets++;
650
651 /* good packet credit */
652 state->sanity_errors >>= 1;
653
654 out_zap_req:
655 skcipher_request_zero(req);
656 return osize;
657
658 sanity_error:
659 if (state->sanity_errors < SANITY_MAX)
660 return DECOMP_ERROR;
661 else
662 /* Take LCP down if the peer is sending too many bogons.
663 * We don't want to do this for a single or just a few
664 * instances since it could just be due to packet corruption.
665 */
666 return DECOMP_FATALERROR;
667 }
668
669 /*
670 * Incompressible data has arrived (this should never happen!).
671 * We should probably drop the link if the protocol is in the range
672 * of what should be encrypted. At the least, we should drop this
673 * packet. (How to do this?)
674 */
mppe_incomp(void * arg,unsigned char * ibuf,int icnt)675 static void mppe_incomp(void *arg, unsigned char *ibuf, int icnt)
676 {
677 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
678
679 if (state->debug &&
680 (PPP_PROTOCOL(ibuf) >= 0x0021 && PPP_PROTOCOL(ibuf) <= 0x00fa))
681 printk(KERN_DEBUG
682 "mppe_incomp[%d]: incompressible (unencrypted) data! "
683 "(proto %04x)\n", state->unit, PPP_PROTOCOL(ibuf));
684
685 state->stats.inc_bytes += icnt;
686 state->stats.inc_packets++;
687 state->stats.unc_bytes += icnt;
688 state->stats.unc_packets++;
689 }
690
691 /*************************************************************
692 * Module interface table
693 *************************************************************/
694
695 /*
696 * Procedures exported to if_ppp.c.
697 */
698 static struct compressor ppp_mppe = {
699 .compress_proto = CI_MPPE,
700 .comp_alloc = mppe_alloc,
701 .comp_free = mppe_free,
702 .comp_init = mppe_comp_init,
703 .comp_reset = mppe_comp_reset,
704 .compress = mppe_compress,
705 .comp_stat = mppe_comp_stats,
706 .decomp_alloc = mppe_alloc,
707 .decomp_free = mppe_free,
708 .decomp_init = mppe_decomp_init,
709 .decomp_reset = mppe_decomp_reset,
710 .decompress = mppe_decompress,
711 .incomp = mppe_incomp,
712 .decomp_stat = mppe_comp_stats,
713 .owner = THIS_MODULE,
714 .comp_extra = MPPE_PAD,
715 };
716
717 /*
718 * ppp_mppe_init()
719 *
720 * Prior to allowing load, try to load the arc4 and sha1 crypto
721 * libraries. The actual use will be allocated later, but
722 * this way the module will fail to insmod if they aren't available.
723 */
724
ppp_mppe_init(void)725 static int __init ppp_mppe_init(void)
726 {
727 int answer;
728 if (!(crypto_has_skcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC) &&
729 crypto_has_ahash("sha1", 0, CRYPTO_ALG_ASYNC)))
730 return -ENODEV;
731
732 sha_pad = kmalloc(sizeof(struct sha_pad), GFP_KERNEL);
733 if (!sha_pad)
734 return -ENOMEM;
735 sha_pad_init(sha_pad);
736
737 answer = ppp_register_compressor(&ppp_mppe);
738
739 if (answer == 0)
740 printk(KERN_INFO "PPP MPPE Compression module registered\n");
741 else
742 kfree(sha_pad);
743
744 return answer;
745 }
746
ppp_mppe_cleanup(void)747 static void __exit ppp_mppe_cleanup(void)
748 {
749 ppp_unregister_compressor(&ppp_mppe);
750 kfree(sha_pad);
751 }
752
753 module_init(ppp_mppe_init);
754 module_exit(ppp_mppe_cleanup);
755