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, 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
46 #include <linux/err.h>
47 #include <linux/module.h>
48 #include <linux/kernel.h>
49 #include <linux/init.h>
50 #include <linux/types.h>
51 #include <linux/slab.h>
52 #include <linux/string.h>
53 #include <linux/crypto.h>
54 #include <linux/mm.h>
55 #include <linux/ppp_defs.h>
56 #include <linux/ppp-comp.h>
57 #include <linux/scatterlist.h>
58
59 #include "ppp_mppe.h"
60
61 MODULE_AUTHOR("Frank Cusack <fcusack@fcusack.com>");
62 MODULE_DESCRIPTION("Point-to-Point Protocol Microsoft Point-to-Point Encryption support");
63 MODULE_LICENSE("Dual BSD/GPL");
64 MODULE_ALIAS("ppp-compress-" __stringify(CI_MPPE));
65 MODULE_VERSION("1.0.2");
66
67 static unsigned int
setup_sg(struct scatterlist * sg,const void * address,unsigned int length)68 setup_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
81 struct sha_pad {
82 unsigned char sha_pad1[SHA1_PAD_SIZE];
83 unsigned char sha_pad2[SHA1_PAD_SIZE];
84 };
85 static struct sha_pad *sha_pad;
86
sha_pad_init(struct sha_pad * shapad)87 static 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 */
96 struct 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 */
get_new_key_from_sha(struct ppp_mppe_state * state)136 static 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 */
mppe_rekey(struct ppp_mppe_state * state,int initial_key)161 static 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 */
mppe_alloc(unsigned char * options,int optlen)193 static 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 */
mppe_free(void * arg)255 static 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 */
272 static int
mppe_init(void * arg,unsigned char * options,int optlen,int unit,int debug,const char * debugstr)273 mppe_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
337 static int
mppe_comp_init(void * arg,unsigned char * options,int optlen,int unit,int hdrlen,int debug)338 mppe_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 */
mppe_comp_reset(void * arg)354 static 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 */
366 static int
mppe_compress(void * arg,unsigned char * ibuf,unsigned char * obuf,int isize,int osize)367 mppe_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 obuf[2] = PPP_COMP >> 8; /* isize + MPPE_OVHD + 1 */
399 obuf[3] = PPP_COMP; /* isize + MPPE_OVHD + 2 */
400 obuf += PPP_HDRLEN;
401
402 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
403 if (state->debug >= 7)
404 printk(KERN_DEBUG "mppe_compress[%d]: ccount %d\n", state->unit,
405 state->ccount);
406 obuf[0] = state->ccount >> 8;
407 obuf[1] = state->ccount & 0xff;
408
409 if (!state->stateful || /* stateless mode */
410 ((state->ccount & 0xff) == 0xff) || /* "flag" packet */
411 (state->bits & MPPE_BIT_FLUSHED)) { /* CCP Reset-Request */
412 /* We must rekey */
413 if (state->debug && state->stateful)
414 printk(KERN_DEBUG "mppe_compress[%d]: rekeying\n",
415 state->unit);
416 mppe_rekey(state, 0);
417 state->bits |= MPPE_BIT_FLUSHED;
418 }
419 obuf[0] |= state->bits;
420 state->bits &= ~MPPE_BIT_FLUSHED; /* reset for next xmit */
421
422 obuf += MPPE_OVHD;
423 ibuf += 2; /* skip to proto field */
424 isize -= 2;
425
426 /* Encrypt packet */
427 sg_init_table(sg_in, 1);
428 sg_init_table(sg_out, 1);
429 setup_sg(sg_in, ibuf, isize);
430 setup_sg(sg_out, obuf, osize);
431 if (crypto_blkcipher_encrypt(&desc, sg_out, sg_in, isize) != 0) {
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 struct blkcipher_desc desc = { .tfm = state->arc4 };
481 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 sg_init_table(sg_in, 1);
617 sg_init_table(sg_out, 1);
618 setup_sg(sg_in, ibuf, 1);
619 setup_sg(sg_out, obuf, 1);
620 if (crypto_blkcipher_decrypt(&desc, sg_out, sg_in, 1) != 0) {
621 printk(KERN_DEBUG "crypto_cypher_decrypt failed\n");
622 return DECOMP_ERROR;
623 }
624
625 /*
626 * Do PFC decompression.
627 * This would be nicer if we were given the actual sk_buff
628 * instead of a char *.
629 */
630 if ((obuf[0] & 0x01) != 0) {
631 obuf[1] = obuf[0];
632 obuf[0] = 0;
633 obuf++;
634 osize++;
635 }
636
637 /* And finally, decrypt the rest of the packet. */
638 setup_sg(sg_in, ibuf + 1, isize - 1);
639 setup_sg(sg_out, obuf + 1, osize - 1);
640 if (crypto_blkcipher_decrypt(&desc, sg_out, sg_in, isize - 1)) {
641 printk(KERN_DEBUG "crypto_cypher_decrypt failed\n");
642 return DECOMP_ERROR;
643 }
644
645 state->stats.unc_bytes += osize;
646 state->stats.unc_packets++;
647 state->stats.comp_bytes += isize;
648 state->stats.comp_packets++;
649
650 /* good packet credit */
651 state->sanity_errors >>= 1;
652
653 return osize;
654 }
655
656 /*
657 * Incompressible data has arrived (this should never happen!).
658 * We should probably drop the link if the protocol is in the range
659 * of what should be encrypted. At the least, we should drop this
660 * packet. (How to do this?)
661 */
mppe_incomp(void * arg,unsigned char * ibuf,int icnt)662 static void mppe_incomp(void *arg, unsigned char *ibuf, int icnt)
663 {
664 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
665
666 if (state->debug &&
667 (PPP_PROTOCOL(ibuf) >= 0x0021 && PPP_PROTOCOL(ibuf) <= 0x00fa))
668 printk(KERN_DEBUG
669 "mppe_incomp[%d]: incompressible (unencrypted) data! "
670 "(proto %04x)\n", state->unit, PPP_PROTOCOL(ibuf));
671
672 state->stats.inc_bytes += icnt;
673 state->stats.inc_packets++;
674 state->stats.unc_bytes += icnt;
675 state->stats.unc_packets++;
676 }
677
678 /*************************************************************
679 * Module interface table
680 *************************************************************/
681
682 /*
683 * Procedures exported to if_ppp.c.
684 */
685 static struct compressor ppp_mppe = {
686 .compress_proto = CI_MPPE,
687 .comp_alloc = mppe_alloc,
688 .comp_free = mppe_free,
689 .comp_init = mppe_comp_init,
690 .comp_reset = mppe_comp_reset,
691 .compress = mppe_compress,
692 .comp_stat = mppe_comp_stats,
693 .decomp_alloc = mppe_alloc,
694 .decomp_free = mppe_free,
695 .decomp_init = mppe_decomp_init,
696 .decomp_reset = mppe_decomp_reset,
697 .decompress = mppe_decompress,
698 .incomp = mppe_incomp,
699 .decomp_stat = mppe_comp_stats,
700 .owner = THIS_MODULE,
701 .comp_extra = MPPE_PAD,
702 };
703
704 /*
705 * ppp_mppe_init()
706 *
707 * Prior to allowing load, try to load the arc4 and sha1 crypto
708 * libraries. The actual use will be allocated later, but
709 * this way the module will fail to insmod if they aren't available.
710 */
711
ppp_mppe_init(void)712 static int __init ppp_mppe_init(void)
713 {
714 int answer;
715 if (!(crypto_has_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC) &&
716 crypto_has_hash("sha1", 0, CRYPTO_ALG_ASYNC)))
717 return -ENODEV;
718
719 sha_pad = kmalloc(sizeof(struct sha_pad), GFP_KERNEL);
720 if (!sha_pad)
721 return -ENOMEM;
722 sha_pad_init(sha_pad);
723
724 answer = ppp_register_compressor(&ppp_mppe);
725
726 if (answer == 0)
727 printk(KERN_INFO "PPP MPPE Compression module registered\n");
728 else
729 kfree(sha_pad);
730
731 return answer;
732 }
733
ppp_mppe_cleanup(void)734 static void __exit ppp_mppe_cleanup(void)
735 {
736 ppp_unregister_compressor(&ppp_mppe);
737 kfree(sha_pad);
738 }
739
740 module_init(ppp_mppe_init);
741 module_exit(ppp_mppe_cleanup);
742