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 struct scatterlist sg_in[1], sg_out[1]; 482 483 if (isize <= PPP_HDRLEN + MPPE_OVHD) { 484 if (state->debug) 485 printk(KERN_DEBUG 486 "mppe_decompress[%d]: short pkt (%d)\n", 487 state->unit, isize); 488 return DECOMP_ERROR; 489 } 490 491 /* 492 * Make sure we have enough room to decrypt the packet. 493 * Note that for our test we only subtract 1 byte whereas in 494 * mppe_compress() we added 2 bytes (+MPPE_OVHD); 495 * this is to account for possible PFC. 496 */ 497 if (osize < isize - MPPE_OVHD - 1) { 498 printk(KERN_DEBUG "mppe_decompress[%d]: osize too small! " 499 "(have: %d need: %d)\n", state->unit, 500 osize, isize - MPPE_OVHD - 1); 501 return DECOMP_ERROR; 502 } 503 osize = isize - MPPE_OVHD - 2; /* assume no PFC */ 504 505 ccount = MPPE_CCOUNT(ibuf); 506 if (state->debug >= 7) 507 printk(KERN_DEBUG "mppe_decompress[%d]: ccount %d\n", 508 state->unit, ccount); 509 510 /* sanity checks -- terminate with extreme prejudice */ 511 if (!(MPPE_BITS(ibuf) & MPPE_BIT_ENCRYPTED)) { 512 printk(KERN_DEBUG 513 "mppe_decompress[%d]: ENCRYPTED bit not set!\n", 514 state->unit); 515 state->sanity_errors += 100; 516 goto sanity_error; 517 } 518 if (!state->stateful && !flushed) { 519 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set in " 520 "stateless mode!\n", state->unit); 521 state->sanity_errors += 100; 522 goto sanity_error; 523 } 524 if (state->stateful && ((ccount & 0xff) == 0xff) && !flushed) { 525 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set on " 526 "flag packet!\n", state->unit); 527 state->sanity_errors += 100; 528 goto sanity_error; 529 } 530 531 /* 532 * Check the coherency count. 533 */ 534 535 if (!state->stateful) { 536 /* Discard late packet */ 537 if ((ccount - state->ccount) % MPPE_CCOUNT_SPACE 538 > MPPE_CCOUNT_SPACE / 2) { 539 state->sanity_errors++; 540 goto sanity_error; 541 } 542 543 /* RFC 3078, sec 8.1. Rekey for every packet. */ 544 while (state->ccount != ccount) { 545 mppe_rekey(state, 0); 546 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE; 547 } 548 } else { 549 /* RFC 3078, sec 8.2. */ 550 if (!state->discard) { 551 /* normal state */ 552 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE; 553 if (ccount != state->ccount) { 554 /* 555 * (ccount > state->ccount) 556 * Packet loss detected, enter the discard state. 557 * Signal the peer to rekey (by sending a CCP Reset-Request). 558 */ 559 state->discard = 1; 560 return DECOMP_ERROR; 561 } 562 } else { 563 /* discard state */ 564 if (!flushed) { 565 /* ccp.c will be silent (no additional CCP Reset-Requests). */ 566 return DECOMP_ERROR; 567 } else { 568 /* Rekey for every missed "flag" packet. */ 569 while ((ccount & ~0xff) != 570 (state->ccount & ~0xff)) { 571 mppe_rekey(state, 0); 572 state->ccount = 573 (state->ccount + 574 256) % MPPE_CCOUNT_SPACE; 575 } 576 577 /* reset */ 578 state->discard = 0; 579 state->ccount = ccount; 580 /* 581 * Another problem with RFC 3078 here. It implies that the 582 * peer need not send a Reset-Ack packet. But RFC 1962 583 * requires it. Hopefully, M$ does send a Reset-Ack; even 584 * though it isn't required for MPPE synchronization, it is 585 * required to reset CCP state. 586 */ 587 } 588 } 589 if (flushed) 590 mppe_rekey(state, 0); 591 } 592 593 /* 594 * Fill in the first part of the PPP header. The protocol field 595 * comes from the decrypted data. 596 */ 597 obuf[0] = PPP_ADDRESS(ibuf); /* +1 */ 598 obuf[1] = PPP_CONTROL(ibuf); /* +1 */ 599 obuf += 2; 600 ibuf += PPP_HDRLEN + MPPE_OVHD; 601 isize -= PPP_HDRLEN + MPPE_OVHD; /* -6 */ 602 /* net osize: isize-4 */ 603 604 /* 605 * Decrypt the first byte in order to check if it is 606 * a compressed or uncompressed protocol field. 607 */ 608 sg_init_table(sg_in, 1); 609 sg_init_table(sg_out, 1); 610 setup_sg(sg_in, ibuf, 1); 611 setup_sg(sg_out, obuf, 1); 612 if (crypto_blkcipher_decrypt(&desc, sg_out, sg_in, 1) != 0) { 613 printk(KERN_DEBUG "crypto_cypher_decrypt failed\n"); 614 return DECOMP_ERROR; 615 } 616 617 /* 618 * Do PFC decompression. 619 * This would be nicer if we were given the actual sk_buff 620 * instead of a char *. 621 */ 622 if ((obuf[0] & 0x01) != 0) { 623 obuf[1] = obuf[0]; 624 obuf[0] = 0; 625 obuf++; 626 osize++; 627 } 628 629 /* And finally, decrypt the rest of the packet. */ 630 setup_sg(sg_in, ibuf + 1, isize - 1); 631 setup_sg(sg_out, obuf + 1, osize - 1); 632 if (crypto_blkcipher_decrypt(&desc, sg_out, sg_in, isize - 1)) { 633 printk(KERN_DEBUG "crypto_cypher_decrypt failed\n"); 634 return DECOMP_ERROR; 635 } 636 637 state->stats.unc_bytes += osize; 638 state->stats.unc_packets++; 639 state->stats.comp_bytes += isize; 640 state->stats.comp_packets++; 641 642 /* good packet credit */ 643 state->sanity_errors >>= 1; 644 645 return osize; 646 647sanity_error: 648 if (state->sanity_errors < SANITY_MAX) 649 return DECOMP_ERROR; 650 else 651 /* Take LCP down if the peer is sending too many bogons. 652 * We don't want to do this for a single or just a few 653 * instances since it could just be due to packet corruption. 654 */ 655 return DECOMP_FATALERROR; 656} 657 658/* 659 * Incompressible data has arrived (this should never happen!). 660 * We should probably drop the link if the protocol is in the range 661 * of what should be encrypted. At the least, we should drop this 662 * packet. (How to do this?) 663 */ 664static void mppe_incomp(void *arg, unsigned char *ibuf, int icnt) 665{ 666 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg; 667 668 if (state->debug && 669 (PPP_PROTOCOL(ibuf) >= 0x0021 && PPP_PROTOCOL(ibuf) <= 0x00fa)) 670 printk(KERN_DEBUG 671 "mppe_incomp[%d]: incompressible (unencrypted) data! " 672 "(proto %04x)\n", state->unit, PPP_PROTOCOL(ibuf)); 673 674 state->stats.inc_bytes += icnt; 675 state->stats.inc_packets++; 676 state->stats.unc_bytes += icnt; 677 state->stats.unc_packets++; 678} 679 680/************************************************************* 681 * Module interface table 682 *************************************************************/ 683 684/* 685 * Procedures exported to if_ppp.c. 686 */ 687static struct compressor ppp_mppe = { 688 .compress_proto = CI_MPPE, 689 .comp_alloc = mppe_alloc, 690 .comp_free = mppe_free, 691 .comp_init = mppe_comp_init, 692 .comp_reset = mppe_comp_reset, 693 .compress = mppe_compress, 694 .comp_stat = mppe_comp_stats, 695 .decomp_alloc = mppe_alloc, 696 .decomp_free = mppe_free, 697 .decomp_init = mppe_decomp_init, 698 .decomp_reset = mppe_decomp_reset, 699 .decompress = mppe_decompress, 700 .incomp = mppe_incomp, 701 .decomp_stat = mppe_comp_stats, 702 .owner = THIS_MODULE, 703 .comp_extra = MPPE_PAD, 704}; 705 706/* 707 * ppp_mppe_init() 708 * 709 * Prior to allowing load, try to load the arc4 and sha1 crypto 710 * libraries. The actual use will be allocated later, but 711 * this way the module will fail to insmod if they aren't available. 712 */ 713 714static int __init ppp_mppe_init(void) 715{ 716 int answer; 717 if (!(crypto_has_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC) && 718 crypto_has_hash("sha1", 0, CRYPTO_ALG_ASYNC))) 719 return -ENODEV; 720 721 sha_pad = kmalloc(sizeof(struct sha_pad), GFP_KERNEL); 722 if (!sha_pad) 723 return -ENOMEM; 724 sha_pad_init(sha_pad); 725 726 answer = ppp_register_compressor(&ppp_mppe); 727 728 if (answer == 0) 729 printk(KERN_INFO "PPP MPPE Compression module registered\n"); 730 else 731 kfree(sha_pad); 732 733 return answer; 734} 735 736static void __exit ppp_mppe_cleanup(void) 737{ 738 ppp_unregister_compressor(&ppp_mppe); 739 kfree(sha_pad); 740} 741 742module_init(ppp_mppe_init); 743module_exit(ppp_mppe_cleanup); 744