root/drivers/net/ppp/ppp_mppe.c

DEFINITIONS

1. sha_pad_init
2. get_new_key_from_sha
3. mppe_rekey
4. mppe_alloc
5. mppe_free
6. mppe_init
7. mppe_comp_init
8. mppe_comp_reset
9. mppe_compress
10. mppe_comp_stats
11. mppe_decomp_init
12. mppe_decomp_reset
13. mppe_decompress
14. mppe_incomp
15. ppp_mppe_init
16. ppp_mppe_cleanup

   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/arc4.h>
  46 #include <crypto/hash.h>
  47 #include <linux/err.h>
  48 #include <linux/fips.h>
  49 #include <linux/module.h>
  50 #include <linux/kernel.h>
  51 #include <linux/init.h>
  52 #include <linux/types.h>
  53 #include <linux/slab.h>
  54 #include <linux/string.h>
  55 #include <linux/mm.h>
  56 #include <linux/ppp_defs.h>
  57 #include <linux/ppp-comp.h>
  58 #include <linux/scatterlist.h>
  59 #include <asm/unaligned.h>
  60 
  61 #include "ppp_mppe.h"
  62 
  63 MODULE_AUTHOR("Frank Cusack <fcusack@fcusack.com>");
  64 MODULE_DESCRIPTION("Point-to-Point Protocol Microsoft Point-to-Point Encryption support");
  65 MODULE_LICENSE("Dual BSD/GPL");
  66 MODULE_ALIAS("ppp-compress-" __stringify(CI_MPPE));
  67 MODULE_VERSION("1.0.2");
  68 
  69 #define SHA1_PAD_SIZE 40
  70 
  71 /*
  72  * kernel crypto API needs its arguments to be in kmalloc'd memory, not in the module
  73  * static data area.  That means sha_pad needs to be kmalloc'd.
  74  */
  75 
  76 struct sha_pad {
  77         unsigned char sha_pad1[SHA1_PAD_SIZE];
  78         unsigned char sha_pad2[SHA1_PAD_SIZE];
  79 };
  80 static struct sha_pad *sha_pad;
  81 
  82 static inline void sha_pad_init(struct sha_pad *shapad)
  83 {
  84         memset(shapad->sha_pad1, 0x00, sizeof(shapad->sha_pad1));
  85         memset(shapad->sha_pad2, 0xF2, sizeof(shapad->sha_pad2));
  86 }
  87 
  88 /*
  89  * State for an MPPE (de)compressor.
  90  */
  91 struct ppp_mppe_state {
  92         struct arc4_ctx arc4;
  93         struct shash_desc *sha1;
  94         unsigned char *sha1_digest;
  95         unsigned char master_key[MPPE_MAX_KEY_LEN];
  96         unsigned char session_key[MPPE_MAX_KEY_LEN];
  97         unsigned keylen;        /* key length in bytes             */
  98         /* NB: 128-bit == 16, 40-bit == 8! */
  99         /* If we want to support 56-bit,   */
 100         /* the unit has to change to bits  */
 101         unsigned char bits;     /* MPPE control bits */
 102         unsigned ccount;        /* 12-bit coherency count (seqno)  */
 103         unsigned stateful;      /* stateful mode flag */
 104         int discard;            /* stateful mode packet loss flag */
 105         int sanity_errors;      /* take down LCP if too many */
 106         int unit;
 107         int debug;
 108         struct compstat stats;
 109 };
 110 
 111 /* struct ppp_mppe_state.bits definitions */
 112 #define MPPE_BIT_A      0x80    /* Encryption table were (re)inititalized */
 113 #define MPPE_BIT_B      0x40    /* MPPC only (not implemented) */
 114 #define MPPE_BIT_C      0x20    /* MPPC only (not implemented) */
 115 #define MPPE_BIT_D      0x10    /* This is an encrypted frame */
 116 
 117 #define MPPE_BIT_FLUSHED        MPPE_BIT_A
 118 #define MPPE_BIT_ENCRYPTED      MPPE_BIT_D
 119 
 120 #define MPPE_BITS(p) ((p)[4] & 0xf0)
 121 #define MPPE_CCOUNT(p) ((((p)[4] & 0x0f) << 8) + (p)[5])
 122 #define MPPE_CCOUNT_SPACE 0x1000        /* The size of the ccount space */
 123 
 124 #define MPPE_OVHD       2       /* MPPE overhead/packet */
 125 #define SANITY_MAX      1600    /* Max bogon factor we will tolerate */
 126 
 127 /*
 128  * Key Derivation, from RFC 3078, RFC 3079.
 129  * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
 130  */
 131 static void get_new_key_from_sha(struct ppp_mppe_state * state)
 132 {
 133         crypto_shash_init(state->sha1);
 134         crypto_shash_update(state->sha1, state->master_key,
 135                             state->keylen);
 136         crypto_shash_update(state->sha1, sha_pad->sha_pad1,
 137                             sizeof(sha_pad->sha_pad1));
 138         crypto_shash_update(state->sha1, state->session_key,
 139                             state->keylen);
 140         crypto_shash_update(state->sha1, sha_pad->sha_pad2,
 141                             sizeof(sha_pad->sha_pad2));
 142         crypto_shash_final(state->sha1, state->sha1_digest);
 143 }
 144 
 145 /*
 146  * Perform the MPPE rekey algorithm, from RFC 3078, sec. 7.3.
 147  * Well, not what's written there, but rather what they meant.
 148  */
 149 static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
 150 {
 151         get_new_key_from_sha(state);
 152         if (!initial_key) {
 153                 arc4_setkey(&state->arc4, state->sha1_digest, state->keylen);
 154                 arc4_crypt(&state->arc4, state->session_key, state->sha1_digest,
 155                            state->keylen);
 156         } else {
 157                 memcpy(state->session_key, state->sha1_digest, state->keylen);
 158         }
 159         if (state->keylen == 8) {
 160                 /* See RFC 3078 */
 161                 state->session_key[0] = 0xd1;
 162                 state->session_key[1] = 0x26;
 163                 state->session_key[2] = 0x9e;
 164         }
 165         arc4_setkey(&state->arc4, state->session_key, state->keylen);
 166 }
 167 
 168 /*
 169  * Allocate space for a (de)compressor.
 170  */
 171 static void *mppe_alloc(unsigned char *options, int optlen)
 172 {
 173         struct ppp_mppe_state *state;
 174         struct crypto_shash *shash;
 175         unsigned int digestsize;
 176 
 177         if (optlen != CILEN_MPPE + sizeof(state->master_key) ||
 178             options[0] != CI_MPPE || options[1] != CILEN_MPPE ||
 179             fips_enabled)
 180                 goto out;
 181 
 182         state = kzalloc(sizeof(*state), GFP_KERNEL);
 183         if (state == NULL)
 184                 goto out;
 185 
 186 
 187         shash = crypto_alloc_shash("sha1", 0, 0);
 188         if (IS_ERR(shash))
 189                 goto out_free;
 190 
 191         state->sha1 = kmalloc(sizeof(*state->sha1) +
 192                                      crypto_shash_descsize(shash),
 193                               GFP_KERNEL);
 194         if (!state->sha1) {
 195                 crypto_free_shash(shash);
 196                 goto out_free;
 197         }
 198         state->sha1->tfm = shash;
 199 
 200         digestsize = crypto_shash_digestsize(shash);
 201         if (digestsize < MPPE_MAX_KEY_LEN)
 202                 goto out_free;
 203 
 204         state->sha1_digest = kmalloc(digestsize, GFP_KERNEL);
 205         if (!state->sha1_digest)
 206                 goto out_free;
 207 
 208         /* Save keys. */
 209         memcpy(state->master_key, &options[CILEN_MPPE],
 210                sizeof(state->master_key));
 211         memcpy(state->session_key, state->master_key,
 212                sizeof(state->master_key));
 213 
 214         /*
 215          * We defer initial key generation until mppe_init(), as mppe_alloc()
 216          * is called frequently during negotiation.
 217          */
 218 
 219         return (void *)state;
 220 
 221 out_free:
 222         kfree(state->sha1_digest);
 223         if (state->sha1) {
 224                 crypto_free_shash(state->sha1->tfm);
 225                 kzfree(state->sha1);
 226         }
 227         kfree(state);
 228 out:
 229         return NULL;
 230 }
 231 
 232 /*
 233  * Deallocate space for a (de)compressor.
 234  */
 235 static void mppe_free(void *arg)
 236 {
 237         struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
 238         if (state) {
 239                 kfree(state->sha1_digest);
 240                 crypto_free_shash(state->sha1->tfm);
 241                 kzfree(state->sha1);
 242                 kzfree(state);
 243         }
 244 }
 245 
 246 /*
 247  * Initialize (de)compressor state.
 248  */
 249 static int
 250 mppe_init(void *arg, unsigned char *options, int optlen, int unit, int debug,
 251           const char *debugstr)
 252 {
 253         struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
 254         unsigned char mppe_opts;
 255 
 256         if (optlen != CILEN_MPPE ||
 257             options[0] != CI_MPPE || options[1] != CILEN_MPPE)
 258                 return 0;
 259 
 260         MPPE_CI_TO_OPTS(&options[2], mppe_opts);
 261         if (mppe_opts & MPPE_OPT_128)
 262                 state->keylen = 16;
 263         else if (mppe_opts & MPPE_OPT_40)
 264                 state->keylen = 8;
 265         else {
 266                 printk(KERN_WARNING "%s[%d]: unknown key length\n", debugstr,
 267                        unit);
 268                 return 0;
 269         }
 270         if (mppe_opts & MPPE_OPT_STATEFUL)
 271                 state->stateful = 1;
 272 
 273         /* Generate the initial session key. */
 274         mppe_rekey(state, 1);
 275 
 276         if (debug) {
 277                 printk(KERN_DEBUG "%s[%d]: initialized with %d-bit %s mode\n",
 278                        debugstr, unit, (state->keylen == 16) ? 128 : 40,
 279                        (state->stateful) ? "stateful" : "stateless");
 280                 printk(KERN_DEBUG
 281                        "%s[%d]: keys: master: %*phN initial session: %*phN\n",
 282                        debugstr, unit,
 283                        (int)sizeof(state->master_key), state->master_key,
 284                        (int)sizeof(state->session_key), state->session_key);
 285         }
 286 
 287         /*
 288          * Initialize the coherency count.  The initial value is not specified
 289          * in RFC 3078, but we can make a reasonable assumption that it will
 290          * start at 0.  Setting it to the max here makes the comp/decomp code
 291          * do the right thing (determined through experiment).
 292          */
 293         state->ccount = MPPE_CCOUNT_SPACE - 1;
 294 
 295         /*
 296          * Note that even though we have initialized the key table, we don't
 297          * set the FLUSHED bit.  This is contrary to RFC 3078, sec. 3.1.
 298          */
 299         state->bits = MPPE_BIT_ENCRYPTED;
 300 
 301         state->unit = unit;
 302         state->debug = debug;
 303 
 304         return 1;
 305 }
 306 
 307 static int
 308 mppe_comp_init(void *arg, unsigned char *options, int optlen, int unit,
 309                int hdrlen, int debug)
 310 {
 311         /* ARGSUSED */
 312         return mppe_init(arg, options, optlen, unit, debug, "mppe_comp_init");
 313 }
 314 
 315 /*
 316  * We received a CCP Reset-Request (actually, we are sending a Reset-Ack),
 317  * tell the compressor to rekey.  Note that we MUST NOT rekey for
 318  * every CCP Reset-Request; we only rekey on the next xmit packet.
 319  * We might get multiple CCP Reset-Requests if our CCP Reset-Ack is lost.
 320  * So, rekeying for every CCP Reset-Request is broken as the peer will not
 321  * know how many times we've rekeyed.  (If we rekey and THEN get another
 322  * CCP Reset-Request, we must rekey again.)
 323  */
 324 static void mppe_comp_reset(void *arg)
 325 {
 326         struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
 327 
 328         state->bits |= MPPE_BIT_FLUSHED;
 329 }
 330 
 331 /*
 332  * Compress (encrypt) a packet.
 333  * It's strange to call this a compressor, since the output is always
 334  * MPPE_OVHD + 2 bytes larger than the input.
 335  */
 336 static int
 337 mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf,
 338               int isize, int osize)
 339 {
 340         struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
 341         int proto;
 342 
 343         /*
 344          * Check that the protocol is in the range we handle.
 345          */
 346         proto = PPP_PROTOCOL(ibuf);
 347         if (proto < 0x0021 || proto > 0x00fa)
 348                 return 0;
 349 
 350         /* Make sure we have enough room to generate an encrypted packet. */
 351         if (osize < isize + MPPE_OVHD + 2) {
 352                 /* Drop the packet if we should encrypt it, but can't. */
 353                 printk(KERN_DEBUG "mppe_compress[%d]: osize too small! "
 354                        "(have: %d need: %d)\n", state->unit,
 355                        osize, osize + MPPE_OVHD + 2);
 356                 return -1;
 357         }
 358 
 359         osize = isize + MPPE_OVHD + 2;
 360 
 361         /*
 362          * Copy over the PPP header and set control bits.
 363          */
 364         obuf[0] = PPP_ADDRESS(ibuf);
 365         obuf[1] = PPP_CONTROL(ibuf);
 366         put_unaligned_be16(PPP_COMP, obuf + 2);
 367         obuf += PPP_HDRLEN;
 368 
 369         state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
 370         if (state->debug >= 7)
 371                 printk(KERN_DEBUG "mppe_compress[%d]: ccount %d\n", state->unit,
 372                        state->ccount);
 373         put_unaligned_be16(state->ccount, obuf);
 374 
 375         if (!state->stateful || /* stateless mode     */
 376             ((state->ccount & 0xff) == 0xff) || /* "flag" packet      */
 377             (state->bits & MPPE_BIT_FLUSHED)) { /* CCP Reset-Request  */
 378                 /* We must rekey */
 379                 if (state->debug && state->stateful)
 380                         printk(KERN_DEBUG "mppe_compress[%d]: rekeying\n",
 381                                state->unit);
 382                 mppe_rekey(state, 0);
 383                 state->bits |= MPPE_BIT_FLUSHED;
 384         }
 385         obuf[0] |= state->bits;
 386         state->bits &= ~MPPE_BIT_FLUSHED;       /* reset for next xmit */
 387 
 388         obuf += MPPE_OVHD;
 389         ibuf += 2;              /* skip to proto field */
 390         isize -= 2;
 391 
 392         arc4_crypt(&state->arc4, obuf, ibuf, isize);
 393 
 394         state->stats.unc_bytes += isize;
 395         state->stats.unc_packets++;
 396         state->stats.comp_bytes += osize;
 397         state->stats.comp_packets++;
 398 
 399         return osize;
 400 }
 401 
 402 /*
 403  * Since every frame grows by MPPE_OVHD + 2 bytes, this is always going
 404  * to look bad ... and the longer the link is up the worse it will get.
 405  */
 406 static void mppe_comp_stats(void *arg, struct compstat *stats)
 407 {
 408         struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
 409 
 410         *stats = state->stats;
 411 }
 412 
 413 static int
 414 mppe_decomp_init(void *arg, unsigned char *options, int optlen, int unit,
 415                  int hdrlen, int mru, int debug)
 416 {
 417         /* ARGSUSED */
 418         return mppe_init(arg, options, optlen, unit, debug, "mppe_decomp_init");
 419 }
 420 
 421 /*
 422  * We received a CCP Reset-Ack.  Just ignore it.
 423  */
 424 static void mppe_decomp_reset(void *arg)
 425 {
 426         /* ARGSUSED */
 427         return;
 428 }
 429 
 430 /*
 431  * Decompress (decrypt) an MPPE packet.
 432  */
 433 static int
 434 mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
 435                 int osize)
 436 {
 437         struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
 438         unsigned ccount;
 439         int flushed = MPPE_BITS(ibuf) & MPPE_BIT_FLUSHED;
 440 
 441         if (isize <= PPP_HDRLEN + MPPE_OVHD) {
 442                 if (state->debug)
 443                         printk(KERN_DEBUG
 444                                "mppe_decompress[%d]: short pkt (%d)\n",
 445                                state->unit, isize);
 446                 return DECOMP_ERROR;
 447         }
 448 
 449         /*
 450          * Make sure we have enough room to decrypt the packet.
 451          * Note that for our test we only subtract 1 byte whereas in
 452          * mppe_compress() we added 2 bytes (+MPPE_OVHD);
 453          * this is to account for possible PFC.
 454          */
 455         if (osize < isize - MPPE_OVHD - 1) {
 456                 printk(KERN_DEBUG "mppe_decompress[%d]: osize too small! "
 457                        "(have: %d need: %d)\n", state->unit,
 458                        osize, isize - MPPE_OVHD - 1);
 459                 return DECOMP_ERROR;
 460         }
 461         osize = isize - MPPE_OVHD - 2;  /* assume no PFC */
 462 
 463         ccount = MPPE_CCOUNT(ibuf);
 464         if (state->debug >= 7)
 465                 printk(KERN_DEBUG "mppe_decompress[%d]: ccount %d\n",
 466                        state->unit, ccount);
 467 
 468         /* sanity checks -- terminate with extreme prejudice */
 469         if (!(MPPE_BITS(ibuf) & MPPE_BIT_ENCRYPTED)) {
 470                 printk(KERN_DEBUG
 471                        "mppe_decompress[%d]: ENCRYPTED bit not set!\n",
 472                        state->unit);
 473                 state->sanity_errors += 100;
 474                 goto sanity_error;
 475         }
 476         if (!state->stateful && !flushed) {
 477                 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set in "
 478                        "stateless mode!\n", state->unit);
 479                 state->sanity_errors += 100;
 480                 goto sanity_error;
 481         }
 482         if (state->stateful && ((ccount & 0xff) == 0xff) && !flushed) {
 483                 printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set on "
 484                        "flag packet!\n", state->unit);
 485                 state->sanity_errors += 100;
 486                 goto sanity_error;
 487         }
 488 
 489         /*
 490          * Check the coherency count.
 491          */
 492 
 493         if (!state->stateful) {
 494                 /* Discard late packet */
 495                 if ((ccount - state->ccount) % MPPE_CCOUNT_SPACE
 496                                                 > MPPE_CCOUNT_SPACE / 2) {
 497                         state->sanity_errors++;
 498                         goto sanity_error;
 499                 }
 500 
 501                 /* RFC 3078, sec 8.1.  Rekey for every packet. */
 502                 while (state->ccount != ccount) {
 503                         mppe_rekey(state, 0);
 504                         state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
 505                 }
 506         } else {
 507                 /* RFC 3078, sec 8.2. */
 508                 if (!state->discard) {
 509                         /* normal state */
 510                         state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
 511                         if (ccount != state->ccount) {
 512                                 /*
 513                                  * (ccount > state->ccount)
 514                                  * Packet loss detected, enter the discard state.
 515                                  * Signal the peer to rekey (by sending a CCP Reset-Request).
 516                                  */
 517                                 state->discard = 1;
 518                                 return DECOMP_ERROR;
 519                         }
 520                 } else {
 521                         /* discard state */
 522                         if (!flushed) {
 523                                 /* ccp.c will be silent (no additional CCP Reset-Requests). */
 524                                 return DECOMP_ERROR;
 525                         } else {
 526                                 /* Rekey for every missed "flag" packet. */
 527                                 while ((ccount & ~0xff) !=
 528                                        (state->ccount & ~0xff)) {
 529                                         mppe_rekey(state, 0);
 530                                         state->ccount =
 531                                             (state->ccount +
 532                                              256) % MPPE_CCOUNT_SPACE;
 533                                 }
 534 
 535                                 /* reset */
 536                                 state->discard = 0;
 537                                 state->ccount = ccount;
 538                                 /*
 539                                  * Another problem with RFC 3078 here.  It implies that the
 540                                  * peer need not send a Reset-Ack packet.  But RFC 1962
 541                                  * requires it.  Hopefully, M$ does send a Reset-Ack; even
 542                                  * though it isn't required for MPPE synchronization, it is
 543                                  * required to reset CCP state.
 544                                  */
 545                         }
 546                 }
 547                 if (flushed)
 548                         mppe_rekey(state, 0);
 549         }
 550 
 551         /*
 552          * Fill in the first part of the PPP header.  The protocol field
 553          * comes from the decrypted data.
 554          */
 555         obuf[0] = PPP_ADDRESS(ibuf);    /* +1 */
 556         obuf[1] = PPP_CONTROL(ibuf);    /* +1 */
 557         obuf += 2;
 558         ibuf += PPP_HDRLEN + MPPE_OVHD;
 559         isize -= PPP_HDRLEN + MPPE_OVHD;        /* -6 */
 560         /* net osize: isize-4 */
 561 
 562         /*
 563          * Decrypt the first byte in order to check if it is
 564          * a compressed or uncompressed protocol field.
 565          */
 566         arc4_crypt(&state->arc4, obuf, ibuf, 1);
 567 
 568         /*
 569          * Do PFC decompression.
 570          * This would be nicer if we were given the actual sk_buff
 571          * instead of a char *.
 572          */
 573         if ((obuf[0] & 0x01) != 0) {
 574                 obuf[1] = obuf[0];
 575                 obuf[0] = 0;
 576                 obuf++;
 577                 osize++;
 578         }
 579 
 580         /* And finally, decrypt the rest of the packet. */
 581         arc4_crypt(&state->arc4, obuf + 1, ibuf + 1, isize - 1);
 582 
 583         state->stats.unc_bytes += osize;
 584         state->stats.unc_packets++;
 585         state->stats.comp_bytes += isize;
 586         state->stats.comp_packets++;
 587 
 588         /* good packet credit */
 589         state->sanity_errors >>= 1;
 590 
 591         return osize;
 592 
 593 sanity_error:
 594         if (state->sanity_errors < SANITY_MAX)
 595                 return DECOMP_ERROR;
 596         else
 597                 /* Take LCP down if the peer is sending too many bogons.
 598                  * We don't want to do this for a single or just a few
 599                  * instances since it could just be due to packet corruption.
 600                  */
 601                 return DECOMP_FATALERROR;
 602 }
 603 
 604 /*
 605  * Incompressible data has arrived (this should never happen!).
 606  * We should probably drop the link if the protocol is in the range
 607  * of what should be encrypted.  At the least, we should drop this
 608  * packet.  (How to do this?)
 609  */
 610 static void mppe_incomp(void *arg, unsigned char *ibuf, int icnt)
 611 {
 612         struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
 613 
 614         if (state->debug &&
 615             (PPP_PROTOCOL(ibuf) >= 0x0021 && PPP_PROTOCOL(ibuf) <= 0x00fa))
 616                 printk(KERN_DEBUG
 617                        "mppe_incomp[%d]: incompressible (unencrypted) data! "
 618                        "(proto %04x)\n", state->unit, PPP_PROTOCOL(ibuf));
 619 
 620         state->stats.inc_bytes += icnt;
 621         state->stats.inc_packets++;
 622         state->stats.unc_bytes += icnt;
 623         state->stats.unc_packets++;
 624 }
 625 
 626 /*************************************************************
 627  * Module interface table
 628  *************************************************************/
 629 
 630 /*
 631  * Procedures exported to if_ppp.c.
 632  */
 633 static struct compressor ppp_mppe = {
 634         .compress_proto = CI_MPPE,
 635         .comp_alloc     = mppe_alloc,
 636         .comp_free      = mppe_free,
 637         .comp_init      = mppe_comp_init,
 638         .comp_reset     = mppe_comp_reset,
 639         .compress       = mppe_compress,
 640         .comp_stat      = mppe_comp_stats,
 641         .decomp_alloc   = mppe_alloc,
 642         .decomp_free    = mppe_free,
 643         .decomp_init    = mppe_decomp_init,
 644         .decomp_reset   = mppe_decomp_reset,
 645         .decompress     = mppe_decompress,
 646         .incomp         = mppe_incomp,
 647         .decomp_stat    = mppe_comp_stats,
 648         .owner          = THIS_MODULE,
 649         .comp_extra     = MPPE_PAD,
 650 };
 651 
 652 /*
 653  * ppp_mppe_init()
 654  *
 655  * Prior to allowing load, try to load the arc4 and sha1 crypto
 656  * libraries.  The actual use will be allocated later, but
 657  * this way the module will fail to insmod if they aren't available.
 658  */
 659 
 660 static int __init ppp_mppe_init(void)
 661 {
 662         int answer;
 663         if (fips_enabled || !crypto_has_ahash("sha1", 0, CRYPTO_ALG_ASYNC))
 664                 return -ENODEV;
 665 
 666         sha_pad = kmalloc(sizeof(struct sha_pad), GFP_KERNEL);
 667         if (!sha_pad)
 668                 return -ENOMEM;
 669         sha_pad_init(sha_pad);
 670 
 671         answer = ppp_register_compressor(&ppp_mppe);
 672 
 673         if (answer == 0)
 674                 printk(KERN_INFO "PPP MPPE Compression module registered\n");
 675         else
 676                 kfree(sha_pad);
 677 
 678         return answer;
 679 }
 680 
 681 static void __exit ppp_mppe_cleanup(void)
 682 {
 683         ppp_unregister_compressor(&ppp_mppe);
 684         kfree(sha_pad);
 685 }
 686 
 687 module_init(ppp_mppe_init);
 688 module_exit(ppp_mppe_cleanup);