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#include <asm/unaligned.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 68static unsigned int 69setup_sg(struct scatterlist *sg, const void *address, unsigned int length) 70{ 71 sg_set_buf(sg, address, length); 72 return length; 73} 74 75#define SHA1_PAD_SIZE 40 76 77/* 78 * kernel crypto API needs its arguments to be in kmalloc'd memory, not in the module 79 * static data area. That means sha_pad needs to be kmalloc'd. 80 */ 81 82struct sha_pad { 83 unsigned char sha_pad1[SHA1_PAD_SIZE]; 84 unsigned char sha_pad2[SHA1_PAD_SIZE]; 85}; 86static struct sha_pad *sha_pad; 87 88static inline void sha_pad_init(struct sha_pad *shapad) 89{ 90 memset(shapad->sha_pad1, 0x00, sizeof(shapad->sha_pad1)); 91 memset(shapad->sha_pad2, 0xF2, sizeof(shapad->sha_pad2)); 92} 93 94/* 95 * State for an MPPE (de)compressor. 96 */ 97struct ppp_mppe_state { 98 struct crypto_blkcipher *arc4; 99 struct crypto_hash *sha1; 100 unsigned char *sha1_digest; 101 unsigned char master_key[MPPE_MAX_KEY_LEN]; 102 unsigned char session_key[MPPE_MAX_KEY_LEN]; 103 unsigned keylen; /* key length in bytes */ 104 /* NB: 128-bit == 16, 40-bit == 8! */ 105 /* If we want to support 56-bit, */ 106 /* the unit has to change to bits */ 107 unsigned char bits; /* MPPE control bits */ 108 unsigned ccount; /* 12-bit coherency count (seqno) */ 109 unsigned stateful; /* stateful mode flag */ 110 int discard; /* stateful mode packet loss flag */ 111 int sanity_errors; /* take down LCP if too many */ 112 int unit; 113 int debug; 114 struct compstat stats; 115}; 116 117/* struct ppp_mppe_state.bits definitions */ 118#define MPPE_BIT_A 0x80 /* Encryption table were (re)inititalized */ 119#define MPPE_BIT_B 0x40 /* MPPC only (not implemented) */ 120#define MPPE_BIT_C 0x20 /* MPPC only (not implemented) */ 121#define MPPE_BIT_D 0x10 /* This is an encrypted frame */ 122 123#define MPPE_BIT_FLUSHED MPPE_BIT_A 124#define MPPE_BIT_ENCRYPTED MPPE_BIT_D 125 126#define MPPE_BITS(p) ((p)[4] & 0xf0) 127#define MPPE_CCOUNT(p) ((((p)[4] & 0x0f) << 8) + (p)[5]) 128#define MPPE_CCOUNT_SPACE 0x1000 /* The size of the ccount space */ 129 130#define MPPE_OVHD 2 /* MPPE overhead/packet */ 131#define SANITY_MAX 1600 /* Max bogon factor we will tolerate */ 132 133/* 134 * Key Derivation, from RFC 3078, RFC 3079. 135 * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079. 136 */ 137static void get_new_key_from_sha(struct ppp_mppe_state * state) 138{ 139 struct hash_desc desc; 140 struct scatterlist sg[4]; 141 unsigned int nbytes; 142 143 sg_init_table(sg, 4); 144 145 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)); 151 152 desc.tfm = state->sha1; 153 desc.flags = 0; 154 155 crypto_hash_digest(&desc, sg, nbytes, state->sha1_digest); 156} 157 158/* 159 * Perform the MPPE rekey algorithm, from RFC 3078, sec. 7.3. 160 * Well, not what's written there, but rather what they meant. 161 */ 162static void mppe_rekey(struct ppp_mppe_state * state, int initial_key) 163{ 164 struct scatterlist sg_in[1], sg_out[1]; 165 struct blkcipher_desc desc = { .tfm = state->arc4 }; 166 167 get_new_key_from_sha(state); 168 if (!initial_key) { 169 crypto_blkcipher_setkey(state->arc4, state->sha1_digest, 170 state->keylen); 171 sg_init_table(sg_in, 1); 172 sg_init_table(sg_out, 1); 173 setup_sg(sg_in, state->sha1_digest, state->keylen); 174 setup_sg(sg_out, state->session_key, state->keylen); 175 if (crypto_blkcipher_encrypt(&desc, sg_out, sg_in, 176 state->keylen) != 0) { 177 printk(KERN_WARNING "mppe_rekey: cipher_encrypt failed\n"); 178 } 179 } else { 180 memcpy(state->session_key, state->sha1_digest, 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 } 188 crypto_blkcipher_setkey(state->arc4, state->session_key, state->keylen); 189} 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; 202 203 state = kzalloc(sizeof(*state), GFP_KERNEL); 204 if (state == NULL) 205 goto out; 206 207 208 state->arc4 = crypto_alloc_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC); 209 if (IS_ERR(state->arc4)) { 210 state->arc4 = NULL; 211 goto out_free; 212 } 213 214 state->sha1 = crypto_alloc_hash("sha1", 0, CRYPTO_ALG_ASYNC); 215 if (IS_ERR(state->sha1)) { 216 state->sha1 = NULL; 217 goto out_free; 218 } 219 220 digestsize = crypto_hash_digestsize(state->sha1); 221 if (digestsize < MPPE_MAX_KEY_LEN) 222 goto out_free; 223 224 state->sha1_digest = kmalloc(digestsize, GFP_KERNEL); 225 if (!state->sha1_digest) 226 goto out_free; 227 228 /* Save keys. */ 229 memcpy(state->master_key, &options[CILEN_MPPE], 230 sizeof(state->master_key)); 231 memcpy(state->session_key, state->master_key, 232 sizeof(state->master_key)); 233 234 /* 235 * We defer initial key generation until mppe_init(), as mppe_alloc() 236 * is called frequently during negotiation. 237 */ 238 239 return (void *)state; 240 241 out_free: 242 if (state->sha1_digest) 243 kfree(state->sha1_digest); 244 if (state->sha1) 245 crypto_free_hash(state->sha1); 246 if (state->arc4) 247 crypto_free_blkcipher(state->arc4); 248 kfree(state); 249 out: 250 return NULL; 251} 252 253/* 254 * Deallocate space for a (de)compressor. 255 */ 256static void mppe_free(void *arg) 257{ 258 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg; 259 if (state) { 260 if (state->sha1_digest) 261 kfree(state->sha1_digest); 262 if (state->sha1) 263 crypto_free_hash(state->sha1); 264 if (state->arc4) 265 crypto_free_blkcipher(state->arc4); 266 kfree(state); 267 } 268} 269 270/* 271 * Initialize (de)compressor state. 272 */ 273static int 274mppe_init(void *arg, unsigned char *options, int optlen, int unit, int debug, 275 const char *debugstr) 276{ 277 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg; 278 unsigned char mppe_opts; 279 280 if (optlen != CILEN_MPPE || 281 options[0] != CI_MPPE || options[1] != CILEN_MPPE) 282 return 0; 283 284 MPPE_CI_TO_OPTS(&options[2], mppe_opts); 285 if (mppe_opts & MPPE_OPT_128) 286 state->keylen = 16; 287 else if (mppe_opts & MPPE_OPT_40) 288 state->keylen = 8; 289 else { 290 printk(KERN_WARNING "%s[%d]: unknown key length\n", debugstr, 291 unit); 292 return 0; 293 } 294 if (mppe_opts & MPPE_OPT_STATEFUL) 295 state->stateful = 1; 296 297 /* Generate the initial session key. */ 298 mppe_rekey(state, 1); 299 300 if (debug) { 301 int i; 302 char mkey[sizeof(state->master_key) * 2 + 1]; 303 char skey[sizeof(state->session_key) * 2 + 1]; 304 305 printk(KERN_DEBUG "%s[%d]: initialized with %d-bit %s mode\n", 306 debugstr, unit, (state->keylen == 16) ? 128 : 40, 307 (state->stateful) ? "stateful" : "stateless"); 308 309 for (i = 0; i < sizeof(state->master_key); i++) 310 sprintf(mkey + i * 2, "%02x", state->master_key[i]); 311 for (i = 0; i < sizeof(state->session_key); i++) 312 sprintf(skey + i * 2, "%02x", state->session_key[i]); 313 printk(KERN_DEBUG 314 "%s[%d]: keys: master: %s initial session: %s\n", 315 debugstr, unit, mkey, skey); 316 } 317 318 /* 319 * Initialize the coherency count. The initial value is not specified 320 * in RFC 3078, but we can make a reasonable assumption that it will 321 * start at 0. Setting it to the max here makes the comp/decomp code 322 * do the right thing (determined through experiment). 323 */ 324 state->ccount = MPPE_CCOUNT_SPACE - 1; 325 326 /* 327 * Note that even though we have initialized the key table, we don't 328 * set the FLUSHED bit. This is contrary to RFC 3078, sec. 3.1. 329 */ 330 state->bits = MPPE_BIT_ENCRYPTED; 331 332 state->unit = unit; 333 state->debug = debug; 334 335 return 1; 336} 337 338static int 339mppe_comp_init(void *arg, unsigned char *options, int optlen, int unit, 340 int hdrlen, int debug) 341{ 342 /* ARGSUSED */ 343 return mppe_init(arg, options, optlen, unit, debug, "mppe_comp_init"); 344} 345 346/* 347 * We received a CCP Reset-Request (actually, we are sending a Reset-Ack), 348 * tell the compressor to rekey. Note that we MUST NOT rekey for 349 * every CCP Reset-Request; we only rekey on the next xmit packet. 350 * We might get multiple CCP Reset-Requests if our CCP Reset-Ack is lost. 351 * So, rekeying for every CCP Reset-Request is broken as the peer will not 352 * know how many times we've rekeyed. (If we rekey and THEN get another 353 * CCP Reset-Request, we must rekey again.) 354 */ 355static void mppe_comp_reset(void *arg) 356{ 357 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg; 358 359 state->bits |= MPPE_BIT_FLUSHED; 360} 361 362/* 363 * Compress (encrypt) a packet. 364 * It's strange to call this a compressor, since the output is always 365 * MPPE_OVHD + 2 bytes larger than the input. 366 */ 367static int 368mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf, 369 int isize, int osize) 370{ 371 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg; 372 struct blkcipher_desc desc = { .tfm = state->arc4 }; 373 int proto; 374 struct scatterlist sg_in[1], sg_out[1]; 375 376 /* 377 * Check that the protocol is in the range we handle. 378 */ 379 proto = PPP_PROTOCOL(ibuf); 380 if (proto < 0x0021 || proto > 0x00fa) 381 return 0; 382 383 /* Make sure we have enough room to generate an encrypted packet. */ 384 if (osize < isize + MPPE_OVHD + 2) { 385 /* Drop the packet if we should encrypt it, but can't. */ 386 printk(KERN_DEBUG "mppe_compress[%d]: osize too small! " 387 "(have: %d need: %d)\n", state->unit, 388 osize, osize + MPPE_OVHD + 2); 389 return -1; 390 } 391 392 osize = isize + MPPE_OVHD + 2; 393 394 /* 395 * Copy over the PPP header and set control bits. 396 */ 397 obuf[0] = PPP_ADDRESS(ibuf); 398 obuf[1] = PPP_CONTROL(ibuf); 399 put_unaligned_be16(PPP_COMP, obuf + 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 put_unaligned_be16(state->ccount, obuf); 407 408 if (!state->stateful || /* stateless mode */ 409 ((state->ccount & 0xff) == 0xff) || /* "flag" packet */ 410 (state->bits & MPPE_BIT_FLUSHED)) { /* CCP Reset-Request */ 411 /* We must rekey */ 412 if (state->debug && state->stateful) 413 printk(KERN_DEBUG "mppe_compress[%d]: rekeying\n", 414 state->unit); 415 mppe_rekey(state, 0); 416 state->bits |= MPPE_BIT_FLUSHED; 417 } 418 obuf[0] |= state->bits; 419 state->bits &= ~MPPE_BIT_FLUSHED; /* reset for next xmit */ 420 421 obuf += MPPE_OVHD; 422 ibuf += 2; /* skip to proto field */ 423 isize -= 2; 424 425 /* Encrypt packet */ 426 sg_init_table(sg_in, 1); 427 sg_init_table(sg_out, 1); 428 setup_sg(sg_in, ibuf, isize); 429 setup_sg(sg_out, obuf, osize); 430 if (crypto_blkcipher_encrypt(&desc, sg_out, sg_in, isize) != 0) { 431 printk(KERN_DEBUG "crypto_cypher_encrypt failed\n"); 432 return -1; 433 } 434 435 state->stats.unc_bytes += isize; 436 state->stats.unc_packets++; 437 state->stats.comp_bytes += osize; 438 state->stats.comp_packets++; 439 440 return osize; 441} 442 443/* 444 * Since every frame grows by MPPE_OVHD + 2 bytes, this is always going 445 * to look bad ... and the longer the link is up the worse it will get. 446 */ 447static void mppe_comp_stats(void *arg, struct compstat *stats) 448{ 449 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg; 450 451 *stats = state->stats; 452} 453 454static int 455mppe_decomp_init(void *arg, unsigned char *options, int optlen, int unit, 456 int hdrlen, int mru, int debug) 457{ 458 /* ARGSUSED */ 459 return mppe_init(arg, options, optlen, unit, debug, "mppe_decomp_init"); 460} 461 462/* 463 * We received a CCP Reset-Ack. Just ignore it. 464 */ 465static void mppe_decomp_reset(void *arg) 466{ 467 /* ARGSUSED */ 468 return; 469} 470 471/* 472 * Decompress (decrypt) an MPPE packet. 473 */ 474static int 475mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf, 476 int osize) 477{ 478 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg; 479 struct blkcipher_desc desc = { .tfm = state->arc4 }; 480 unsigned ccount; 481 int flushed = MPPE_BITS(ibuf) & MPPE_BIT_FLUSHED; 482 int sanity = 0; 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 sanity = 1; 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 sanity = 1; 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 sanity = 1; 531 } 532 533 if (sanity) { 534 if (state->sanity_errors < SANITY_MAX) 535 return DECOMP_ERROR; 536 else 537 /* 538 * Take LCP down if the peer is sending too many bogons. 539 * We don't want to do this for a single or just a few 540 * instances since it could just be due to packet corruption. 541 */ 542 return DECOMP_FATALERROR; 543 } 544 545 /* 546 * Check the coherency count. 547 */ 548 549 if (!state->stateful) { 550 /* RFC 3078, sec 8.1. Rekey for every packet. */ 551 while (state->ccount != ccount) { 552 mppe_rekey(state, 0); 553 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE; 554 } 555 } else { 556 /* RFC 3078, sec 8.2. */ 557 if (!state->discard) { 558 /* normal state */ 559 state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE; 560 if (ccount != state->ccount) { 561 /* 562 * (ccount > state->ccount) 563 * Packet loss detected, enter the discard state. 564 * Signal the peer to rekey (by sending a CCP Reset-Request). 565 */ 566 state->discard = 1; 567 return DECOMP_ERROR; 568 } 569 } else { 570 /* discard state */ 571 if (!flushed) { 572 /* ccp.c will be silent (no additional CCP Reset-Requests). */ 573 return DECOMP_ERROR; 574 } else { 575 /* Rekey for every missed "flag" packet. */ 576 while ((ccount & ~0xff) != 577 (state->ccount & ~0xff)) { 578 mppe_rekey(state, 0); 579 state->ccount = 580 (state->ccount + 581 256) % MPPE_CCOUNT_SPACE; 582 } 583 584 /* reset */ 585 state->discard = 0; 586 state->ccount = ccount; 587 /* 588 * Another problem with RFC 3078 here. It implies that the 589 * peer need not send a Reset-Ack packet. But RFC 1962 590 * requires it. Hopefully, M$ does send a Reset-Ack; even 591 * though it isn't required for MPPE synchronization, it is 592 * required to reset CCP state. 593 */ 594 } 595 } 596 if (flushed) 597 mppe_rekey(state, 0); 598 } 599 600 /* 601 * Fill in the first part of the PPP header. The protocol field 602 * comes from the decrypted data. 603 */ 604 obuf[0] = PPP_ADDRESS(ibuf); /* +1 */ 605 obuf[1] = PPP_CONTROL(ibuf); /* +1 */ 606 obuf += 2; 607 ibuf += PPP_HDRLEN + MPPE_OVHD; 608 isize -= PPP_HDRLEN + MPPE_OVHD; /* -6 */ 609 /* net osize: isize-4 */ 610 611 /* 612 * Decrypt the first byte in order to check if it is 613 * a compressed or uncompressed protocol field. 614 */ 615 sg_init_table(sg_in, 1); 616 sg_init_table(sg_out, 1); 617 setup_sg(sg_in, ibuf, 1); 618 setup_sg(sg_out, obuf, 1); 619 if (crypto_blkcipher_decrypt(&desc, sg_out, sg_in, 1) != 0) { 620 printk(KERN_DEBUG "crypto_cypher_decrypt failed\n"); 621 return DECOMP_ERROR; 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 if (crypto_blkcipher_decrypt(&desc, sg_out, sg_in, isize - 1)) { 640 printk(KERN_DEBUG "crypto_cypher_decrypt failed\n"); 641 return DECOMP_ERROR; 642 } 643 644 state->stats.unc_bytes += osize; 645 state->stats.unc_packets++; 646 state->stats.comp_bytes += isize; 647 state->stats.comp_packets++; 648 649 /* good packet credit */ 650 state->sanity_errors >>= 1; 651 652 return osize; 653} 654 655/* 656 * Incompressible data has arrived (this should never happen!). 657 * We should probably drop the link if the protocol is in the range 658 * of what should be encrypted. At the least, we should drop this 659 * packet. (How to do this?) 660 */ 661static void mppe_incomp(void *arg, unsigned char *ibuf, int icnt) 662{ 663 struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg; 664 665 if (state->debug && 666 (PPP_PROTOCOL(ibuf) >= 0x0021 && PPP_PROTOCOL(ibuf) <= 0x00fa)) 667 printk(KERN_DEBUG 668 "mppe_incomp[%d]: incompressible (unencrypted) data! " 669 "(proto %04x)\n", state->unit, PPP_PROTOCOL(ibuf)); 670 671 state->stats.inc_bytes += icnt; 672 state->stats.inc_packets++; 673 state->stats.unc_bytes += icnt; 674 state->stats.unc_packets++; 675} 676 677/************************************************************* 678 * Module interface table 679 *************************************************************/ 680 681/* 682 * Procedures exported to if_ppp.c. 683 */ 684static struct compressor ppp_mppe = { 685 .compress_proto = CI_MPPE, 686 .comp_alloc = mppe_alloc, 687 .comp_free = mppe_free, 688 .comp_init = mppe_comp_init, 689 .comp_reset = mppe_comp_reset, 690 .compress = mppe_compress, 691 .comp_stat = mppe_comp_stats, 692 .decomp_alloc = mppe_alloc, 693 .decomp_free = mppe_free, 694 .decomp_init = mppe_decomp_init, 695 .decomp_reset = mppe_decomp_reset, 696 .decompress = mppe_decompress, 697 .incomp = mppe_incomp, 698 .decomp_stat = mppe_comp_stats, 699 .owner = THIS_MODULE, 700 .comp_extra = MPPE_PAD, 701}; 702 703/* 704 * ppp_mppe_init() 705 * 706 * Prior to allowing load, try to load the arc4 and sha1 crypto 707 * libraries. The actual use will be allocated later, but 708 * this way the module will fail to insmod if they aren't available. 709 */ 710 711static int __init ppp_mppe_init(void) 712{ 713 int answer; 714 if (!(crypto_has_blkcipher("ecb(arc4)", 0, CRYPTO_ALG_ASYNC) && 715 crypto_has_hash("sha1", 0, CRYPTO_ALG_ASYNC))) 716 return -ENODEV; 717 718 sha_pad = kmalloc(sizeof(struct sha_pad), GFP_KERNEL); 719 if (!sha_pad) 720 return -ENOMEM; 721 sha_pad_init(sha_pad); 722 723 answer = ppp_register_compressor(&ppp_mppe); 724 725 if (answer == 0) 726 printk(KERN_INFO "PPP MPPE Compression module registered\n"); 727 else 728 kfree(sha_pad); 729 730 return answer; 731} 732 733static void __exit ppp_mppe_cleanup(void) 734{ 735 ppp_unregister_compressor(&ppp_mppe); 736 kfree(sha_pad); 737} 738 739module_init(ppp_mppe_init); 740module_exit(ppp_mppe_cleanup); 741