1 2 /* 3 * ng_mppc.c 4 * 5 * Copyright (c) 1996-2000 Whistle Communications, Inc. 6 * All rights reserved. 7 * 8 * Subject to the following obligations and disclaimer of warranty, use and 9 * redistribution of this software, in source or object code forms, with or 10 * without modifications are expressly permitted by Whistle Communications; 11 * provided, however, that: 12 * 1. Any and all reproductions of the source or object code must include the 13 * copyright notice above and the following disclaimer of warranties; and 14 * 2. No rights are granted, in any manner or form, to use Whistle 15 * Communications, Inc. trademarks, including the mark "WHISTLE 16 * COMMUNICATIONS" on advertising, endorsements, or otherwise except as 17 * such appears in the above copyright notice or in the software. 18 * 19 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND 20 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO 21 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE, 22 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF 23 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. 24 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY 25 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS 26 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE. 27 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES 28 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING 29 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, 30 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR 31 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY 32 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 33 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 34 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY 35 * OF SUCH DAMAGE. 36 * 37 * Author: Archie Cobbs <archie@freebsd.org> 38 * 39 * $Whistle: ng_mppc.c,v 1.4 1999/11/25 00:10:12 archie Exp $ 40 * $FreeBSD: src/sys/netgraph/ng_mppc.c,v 1.1.2.7 2002/12/16 17:58:42 archie Exp $ 41 * $DragonFly: src/sys/netgraph/mppc/ng_mppc.c,v 1.5 2005/02/17 13:59:59 joerg Exp $ 42 */ 43 44 /* 45 * Microsoft PPP compression (MPPC) and encryption (MPPE) netgraph node type. 46 * 47 * You must define one or both of the NETGRAPH_MPPC_COMPRESSION and/or 48 * NETGRAPH_MPPC_ENCRYPTION options for this node type to be useful. 49 */ 50 51 #include <sys/param.h> 52 #include <sys/systm.h> 53 #include <sys/kernel.h> 54 #include <sys/conf.h> 55 #include <sys/mbuf.h> 56 #include <sys/malloc.h> 57 #include <sys/errno.h> 58 #include <sys/syslog.h> 59 60 #include <netgraph/ng_message.h> 61 #include <netgraph/netgraph.h> 62 #include "ng_mppc.h" 63 64 #include "opt_netgraph.h" 65 66 #if !defined(NETGRAPH_MPPC_COMPRESSION) && !defined(NETGRAPH_MPPC_ENCRYPTION) 67 #error Need either NETGRAPH_MPPC_COMPRESSION or NETGRAPH_MPPC_ENCRYPTION 68 #endif 69 70 #ifdef NETGRAPH_MPPC_COMPRESSION 71 /* XXX this file doesn't exist yet, but hopefully someday it will... */ 72 #include <net/mppc.h> 73 #endif 74 #ifdef NETGRAPH_MPPC_ENCRYPTION 75 #include <crypto/rc4/rc4.h> 76 #endif 77 #include <crypto/sha1.h> 78 79 /* Decompression blowup */ 80 #define MPPC_DECOMP_BUFSIZE 8092 /* allocate buffer this big */ 81 #define MPPC_DECOMP_SAFETY 100 /* plus this much margin */ 82 83 /* MPPC/MPPE header length */ 84 #define MPPC_HDRLEN 2 85 86 /* Key length */ 87 #define KEYLEN(b) (((b) & MPPE_128) ? 16 : 8) 88 89 /* 90 * When packets are lost with MPPE, we may have to re-key arbitrarily 91 * many times to 'catch up' to the new jumped-ahead sequence number. 92 * Since this can be expensive, we pose a limit on how many re-keyings 93 * we will do at one time to avoid a possible D.O.S. vulnerability. 94 * This should instead be a configurable parameter. 95 */ 96 #define MPPE_MAX_REKEY 1000 97 98 /* MPPC packet header bits */ 99 #define MPPC_FLAG_FLUSHED 0x8000 /* xmitter reset state */ 100 #define MPPC_FLAG_RESTART 0x4000 /* compress history restart */ 101 #define MPPC_FLAG_COMPRESSED 0x2000 /* packet is compresed */ 102 #define MPPC_FLAG_ENCRYPTED 0x1000 /* packet is encrypted */ 103 #define MPPC_CCOUNT_MASK 0x0fff /* sequence number mask */ 104 105 #define MPPE_UPDATE_MASK 0xff /* coherency count when we're */ 106 #define MPPE_UPDATE_FLAG 0xff /* supposed to update key */ 107 108 #define MPPC_COMP_OK 0x05 109 #define MPPC_DECOMP_OK 0x05 110 111 /* Per direction info */ 112 struct ng_mppc_dir { 113 struct ng_mppc_config cfg; /* configuration */ 114 hook_p hook; /* netgraph hook */ 115 u_int16_t cc:12; /* coherency count */ 116 u_char flushed; /* clean history (xmit only) */ 117 #ifdef NETGRAPH_MPPC_COMPRESSION 118 u_char *history; /* compression history */ 119 #endif 120 #ifdef NETGRAPH_MPPC_ENCRYPTION 121 u_char key[MPPE_KEY_LEN]; /* session key */ 122 struct rc4_state rc4; /* rc4 state */ 123 #endif 124 }; 125 126 /* Node private data */ 127 struct ng_mppc_private { 128 struct ng_mppc_dir xmit; /* compress/encrypt config */ 129 struct ng_mppc_dir recv; /* decompress/decrypt config */ 130 char *ctrlpath; /* path to controlling node */ 131 }; 132 typedef struct ng_mppc_private *priv_p; 133 134 /* Netgraph node methods */ 135 static ng_constructor_t ng_mppc_constructor; 136 static ng_rcvmsg_t ng_mppc_rcvmsg; 137 static ng_shutdown_t ng_mppc_rmnode; 138 static ng_newhook_t ng_mppc_newhook; 139 static ng_rcvdata_t ng_mppc_rcvdata; 140 static ng_disconnect_t ng_mppc_disconnect; 141 142 /* Helper functions */ 143 static int ng_mppc_compress(node_p node, 144 struct mbuf *m, struct mbuf **resultp); 145 static int ng_mppc_decompress(node_p node, 146 struct mbuf *m, struct mbuf **resultp); 147 static void ng_mppc_getkey(const u_char *h, u_char *h2, int len); 148 static void ng_mppc_updatekey(u_int32_t bits, 149 u_char *key0, u_char *key, struct rc4_state *rc4); 150 static void ng_mppc_reset_req(node_p node); 151 152 /* Node type descriptor */ 153 static struct ng_type ng_mppc_typestruct = { 154 NG_VERSION, 155 NG_MPPC_NODE_TYPE, 156 NULL, 157 ng_mppc_constructor, 158 ng_mppc_rcvmsg, 159 ng_mppc_rmnode, 160 ng_mppc_newhook, 161 NULL, 162 NULL, 163 ng_mppc_rcvdata, 164 ng_mppc_rcvdata, 165 ng_mppc_disconnect, 166 NULL 167 }; 168 NETGRAPH_INIT(mppc, &ng_mppc_typestruct); 169 170 /* Fixed bit pattern to weaken keysize down to 40 or 56 bits */ 171 static const u_char ng_mppe_weakenkey[3] = { 0xd1, 0x26, 0x9e }; 172 173 #define ERROUT(x) do { error = (x); goto done; } while (0) 174 175 /************************************************************************ 176 NETGRAPH NODE STUFF 177 ************************************************************************/ 178 179 /* 180 * Node type constructor 181 */ 182 static int 183 ng_mppc_constructor(node_p *nodep) 184 { 185 priv_p priv; 186 int error; 187 188 /* Allocate private structure */ 189 MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH, M_NOWAIT); 190 if (priv == NULL) 191 return (ENOMEM); 192 bzero(priv, sizeof(*priv)); 193 194 /* Call generic node constructor */ 195 if ((error = ng_make_node_common(&ng_mppc_typestruct, nodep))) { 196 FREE(priv, M_NETGRAPH); 197 return (error); 198 } 199 (*nodep)->private = priv; 200 201 /* Done */ 202 return (0); 203 } 204 205 /* 206 * Give our OK for a hook to be added 207 */ 208 static int 209 ng_mppc_newhook(node_p node, hook_p hook, const char *name) 210 { 211 const priv_p priv = node->private; 212 hook_p *hookPtr; 213 214 /* Check hook name */ 215 if (strcmp(name, NG_MPPC_HOOK_COMP) == 0) 216 hookPtr = &priv->xmit.hook; 217 else if (strcmp(name, NG_MPPC_HOOK_DECOMP) == 0) 218 hookPtr = &priv->recv.hook; 219 else 220 return (EINVAL); 221 222 /* See if already connected */ 223 if (*hookPtr != NULL) 224 return (EISCONN); 225 226 /* OK */ 227 *hookPtr = hook; 228 return (0); 229 } 230 231 /* 232 * Receive a control message 233 */ 234 static int 235 ng_mppc_rcvmsg(node_p node, struct ng_mesg *msg, 236 const char *raddr, struct ng_mesg **rptr) 237 { 238 const priv_p priv = node->private; 239 struct ng_mesg *resp = NULL; 240 int error = 0; 241 242 switch (msg->header.typecookie) { 243 case NGM_MPPC_COOKIE: 244 switch (msg->header.cmd) { 245 case NGM_MPPC_CONFIG_COMP: 246 case NGM_MPPC_CONFIG_DECOMP: 247 { 248 struct ng_mppc_config *const cfg 249 = (struct ng_mppc_config *)msg->data; 250 const int isComp = 251 msg->header.cmd == NGM_MPPC_CONFIG_COMP; 252 struct ng_mppc_dir *const d = isComp ? 253 &priv->xmit : &priv->recv; 254 255 /* Check configuration */ 256 if (msg->header.arglen != sizeof(*cfg)) 257 ERROUT(EINVAL); 258 if (cfg->enable) { 259 if ((cfg->bits & ~MPPC_VALID_BITS) != 0) 260 ERROUT(EINVAL); 261 #ifndef NETGRAPH_MPPC_COMPRESSION 262 if ((cfg->bits & MPPC_BIT) != 0) 263 ERROUT(EPROTONOSUPPORT); 264 #endif 265 #ifndef NETGRAPH_MPPC_ENCRYPTION 266 if ((cfg->bits & MPPE_BITS) != 0) 267 ERROUT(EPROTONOSUPPORT); 268 #endif 269 } else 270 cfg->bits = 0; 271 272 /* Save return address so we can send reset-req's */ 273 if (!isComp && priv->ctrlpath != NULL) { 274 FREE(priv->ctrlpath, M_NETGRAPH); 275 priv->ctrlpath = NULL; 276 } 277 if (!isComp && raddr != NULL) { 278 MALLOC(priv->ctrlpath, char *, 279 strlen(raddr) + 1, M_NETGRAPH, M_NOWAIT); 280 if (priv->ctrlpath == NULL) 281 ERROUT(ENOMEM); 282 strcpy(priv->ctrlpath, raddr); 283 } 284 285 /* Configuration is OK, reset to it */ 286 d->cfg = *cfg; 287 288 #ifdef NETGRAPH_MPPC_COMPRESSION 289 /* Initialize state buffers for compression */ 290 if (d->history != NULL) { 291 FREE(d->history, M_NETGRAPH); 292 d->history = NULL; 293 } 294 if ((cfg->bits & MPPC_BIT) != 0) { 295 MALLOC(d->history, u_char *, 296 isComp ? MPPC_SizeOfCompressionHistory() : 297 MPPC_SizeOfDecompressionHistory(), 298 M_NETGRAPH, M_NOWAIT); 299 if (d->history == NULL) 300 ERROUT(ENOMEM); 301 if (isComp) 302 MPPC_InitCompressionHistory(d->history); 303 else { 304 MPPC_InitDecompressionHistory( 305 d->history); 306 } 307 } 308 #endif 309 310 #ifdef NETGRAPH_MPPC_ENCRYPTION 311 /* Generate initial session keys for encryption */ 312 if ((cfg->bits & MPPE_BITS) != 0) { 313 const int keylen = KEYLEN(cfg->bits); 314 315 bcopy(cfg->startkey, d->key, keylen); 316 ng_mppc_getkey(cfg->startkey, d->key, keylen); 317 if ((cfg->bits & MPPE_40) != 0) 318 bcopy(&ng_mppe_weakenkey, d->key, 3); 319 else if ((cfg->bits & MPPE_56) != 0) 320 bcopy(&ng_mppe_weakenkey, d->key, 1); 321 rc4_init(&d->rc4, d->key, keylen); 322 } 323 #endif 324 325 /* Initialize other state */ 326 d->cc = 0; 327 d->flushed = 0; 328 break; 329 } 330 331 case NGM_MPPC_RESETREQ: 332 ng_mppc_reset_req(node); 333 break; 334 335 default: 336 error = EINVAL; 337 break; 338 } 339 break; 340 default: 341 error = EINVAL; 342 break; 343 } 344 if (rptr) 345 *rptr = resp; 346 else if (resp) 347 FREE(resp, M_NETGRAPH); 348 349 done: 350 FREE(msg, M_NETGRAPH); 351 return (error); 352 } 353 354 /* 355 * Receive incoming data on our hook. 356 */ 357 static int 358 ng_mppc_rcvdata(hook_p hook, struct mbuf *m, meta_p meta) 359 { 360 const node_p node = hook->node; 361 const priv_p priv = node->private; 362 struct mbuf *out; 363 int error; 364 365 /* Compress and/or encrypt */ 366 if (hook == priv->xmit.hook) { 367 if (!priv->xmit.cfg.enable) { 368 NG_FREE_DATA(m, meta); 369 return (ENXIO); 370 } 371 if ((error = ng_mppc_compress(node, m, &out)) != 0) { 372 NG_FREE_DATA(m, meta); 373 return(error); 374 } 375 m_freem(m); 376 NG_SEND_DATA(error, priv->xmit.hook, out, meta); 377 return (error); 378 } 379 380 /* Decompress and/or decrypt */ 381 if (hook == priv->recv.hook) { 382 if (!priv->recv.cfg.enable) { 383 NG_FREE_DATA(m, meta); 384 return (ENXIO); 385 } 386 if ((error = ng_mppc_decompress(node, m, &out)) != 0) { 387 NG_FREE_DATA(m, meta); 388 if (error == EINVAL && priv->ctrlpath != NULL) { 389 struct ng_mesg *msg; 390 391 /* Need to send a reset-request */ 392 NG_MKMESSAGE(msg, NGM_MPPC_COOKIE, 393 NGM_MPPC_RESETREQ, 0, M_NOWAIT); 394 if (msg == NULL) 395 return (error); 396 ng_send_msg(node, msg, priv->ctrlpath, NULL); 397 } 398 return (error); 399 } 400 m_freem(m); 401 NG_SEND_DATA(error, priv->recv.hook, out, meta); 402 return (error); 403 } 404 405 /* Oops */ 406 panic("%s: unknown hook", __func__); 407 } 408 409 /* 410 * Destroy node 411 */ 412 static int 413 ng_mppc_rmnode(node_p node) 414 { 415 const priv_p priv = node->private; 416 417 /* Take down netgraph node */ 418 node->flags |= NG_INVALID; 419 ng_cutlinks(node); 420 ng_unname(node); 421 if (priv->ctrlpath != NULL) 422 FREE(priv->ctrlpath, M_NETGRAPH); 423 #ifdef NETGRAPH_MPPC_COMPRESSION 424 if (priv->xmit.history != NULL) 425 FREE(priv->xmit.history, M_NETGRAPH); 426 if (priv->recv.history != NULL) 427 FREE(priv->recv.history, M_NETGRAPH); 428 #endif 429 bzero(priv, sizeof(*priv)); 430 FREE(priv, M_NETGRAPH); 431 node->private = NULL; 432 ng_unref(node); /* let the node escape */ 433 return (0); 434 } 435 436 /* 437 * Hook disconnection 438 */ 439 static int 440 ng_mppc_disconnect(hook_p hook) 441 { 442 const node_p node = hook->node; 443 const priv_p priv = node->private; 444 445 /* Zero out hook pointer */ 446 if (hook == priv->xmit.hook) 447 priv->xmit.hook = NULL; 448 if (hook == priv->recv.hook) 449 priv->recv.hook = NULL; 450 451 /* Go away if no longer connected */ 452 if (node->numhooks == 0) 453 ng_rmnode(node); 454 return (0); 455 } 456 457 /************************************************************************ 458 HELPER STUFF 459 ************************************************************************/ 460 461 /* 462 * Compress/encrypt a packet and put the result in a new mbuf at *resultp. 463 * The original mbuf is not free'd. 464 */ 465 static int 466 ng_mppc_compress(node_p node, struct mbuf *m, struct mbuf **resultp) 467 { 468 const priv_p priv = node->private; 469 struct ng_mppc_dir *const d = &priv->xmit; 470 u_char *inbuf, *outbuf; 471 int outlen, inlen; 472 u_int16_t header; 473 474 /* Initialize */ 475 *resultp = NULL; 476 header = d->cc; 477 if (d->flushed) { 478 header |= MPPC_FLAG_FLUSHED; 479 d->flushed = 0; 480 } 481 482 /* Work with contiguous regions of memory */ 483 inlen = m->m_pkthdr.len; 484 MALLOC(inbuf, u_char *, inlen, M_NETGRAPH, M_NOWAIT); 485 if (inbuf == NULL) 486 return (ENOMEM); 487 m_copydata(m, 0, inlen, (caddr_t)inbuf); 488 if ((d->cfg.bits & MPPC_BIT) != 0) 489 outlen = MPPC_MAX_BLOWUP(inlen); 490 else 491 outlen = MPPC_HDRLEN + inlen; 492 MALLOC(outbuf, u_char *, outlen, M_NETGRAPH, M_NOWAIT); 493 if (outbuf == NULL) { 494 FREE(inbuf, M_NETGRAPH); 495 return (ENOMEM); 496 } 497 498 /* Compress "inbuf" into "outbuf" (if compression enabled) */ 499 #ifdef NETGRAPH_MPPC_COMPRESSION 500 if ((d->cfg.bits & MPPC_BIT) != 0) { 501 u_short flags = MPPC_MANDATORY_COMPRESS_FLAGS; 502 u_char *source, *dest; 503 u_long sourceCnt, destCnt; 504 int rtn; 505 506 /* Prepare to compress */ 507 source = inbuf; 508 sourceCnt = inlen; 509 dest = outbuf + MPPC_HDRLEN; 510 destCnt = outlen - MPPC_HDRLEN; 511 if ((d->cfg.bits & MPPE_STATELESS) == 0) 512 flags |= MPPC_SAVE_HISTORY; 513 514 /* Compress */ 515 rtn = MPPC_Compress(&source, &dest, &sourceCnt, 516 &destCnt, d->history, flags, 0); 517 518 /* Check return value */ 519 KASSERT(rtn != MPPC_INVALID, ("%s: invalid", __func__)); 520 if ((rtn & MPPC_EXPANDED) == 0 521 && (rtn & MPPC_COMP_OK) == MPPC_COMP_OK) { 522 outlen -= destCnt; 523 header |= MPPC_FLAG_COMPRESSED; 524 if ((rtn & MPPC_RESTART_HISTORY) != 0) 525 header |= MPPC_FLAG_RESTART; 526 } 527 d->flushed = (rtn & MPPC_EXPANDED) != 0 528 || (flags & MPPC_SAVE_HISTORY) == 0; 529 } 530 #endif 531 532 /* If we did not compress this packet, copy it to output buffer */ 533 if ((header & MPPC_FLAG_COMPRESSED) == 0) { 534 bcopy(inbuf, outbuf + MPPC_HDRLEN, inlen); 535 outlen = MPPC_HDRLEN + inlen; 536 } 537 FREE(inbuf, M_NETGRAPH); 538 539 /* Always set the flushed bit in stateless mode */ 540 if ((d->cfg.bits & MPPE_STATELESS) != 0) 541 header |= MPPC_FLAG_FLUSHED; 542 543 /* Now encrypt packet (if encryption enabled) */ 544 #ifdef NETGRAPH_MPPC_ENCRYPTION 545 if ((d->cfg.bits & MPPE_BITS) != 0) { 546 547 /* Set header bits; need to reset key if we say we did */ 548 header |= MPPC_FLAG_ENCRYPTED; 549 if ((header & MPPC_FLAG_FLUSHED) != 0) 550 rc4_init(&d->rc4, d->key, KEYLEN(d->cfg.bits)); 551 552 /* Update key if it's time */ 553 if ((d->cfg.bits & MPPE_STATELESS) != 0 554 || (d->cc & MPPE_UPDATE_MASK) == MPPE_UPDATE_FLAG) { 555 ng_mppc_updatekey(d->cfg.bits, 556 d->cfg.startkey, d->key, &d->rc4); 557 } 558 559 /* Encrypt packet */ 560 rc4_crypt(&d->rc4, outbuf + MPPC_HDRLEN, 561 outbuf + MPPC_HDRLEN, outlen - MPPC_HDRLEN); 562 } 563 #endif 564 565 /* Update sequence number */ 566 d->cc++; 567 568 /* Install header */ 569 *((u_int16_t *)outbuf) = htons(header); 570 571 /* Return packet in an mbuf */ 572 *resultp = m_devget((caddr_t)outbuf, outlen, 0, NULL, NULL); 573 FREE(outbuf, M_NETGRAPH); 574 return (*resultp == NULL ? ENOBUFS : 0); 575 } 576 577 /* 578 * Decompress/decrypt packet and put the result in a new mbuf at *resultp. 579 * The original mbuf is not free'd. 580 */ 581 static int 582 ng_mppc_decompress(node_p node, struct mbuf *m, struct mbuf **resultp) 583 { 584 const priv_p priv = node->private; 585 struct ng_mppc_dir *const d = &priv->recv; 586 u_int16_t header, cc; 587 u_int numLost; 588 u_char *buf; 589 int len; 590 591 /* Pull off header */ 592 if (m->m_pkthdr.len < MPPC_HDRLEN) 593 return (EINVAL); 594 m_copydata(m, 0, MPPC_HDRLEN, (caddr_t)&header); 595 header = ntohs(header); 596 cc = (header & MPPC_CCOUNT_MASK); 597 598 /* Copy payload into a contiguous region of memory */ 599 len = m->m_pkthdr.len - MPPC_HDRLEN; 600 MALLOC(buf, u_char *, len, M_NETGRAPH, M_NOWAIT); 601 if (buf == NULL) 602 return (ENOMEM); 603 m_copydata(m, MPPC_HDRLEN, len, (caddr_t)buf); 604 605 /* Check for an unexpected jump in the sequence number */ 606 numLost = ((cc - d->cc) & MPPC_CCOUNT_MASK); 607 608 /* If flushed bit set, we can always handle packet */ 609 if ((header & MPPC_FLAG_FLUSHED) != 0) { 610 #ifdef NETGRAPH_MPPC_COMPRESSION 611 if (d->history != NULL) 612 MPPC_InitDecompressionHistory(d->history); 613 #endif 614 #ifdef NETGRAPH_MPPC_ENCRYPTION 615 if ((d->cfg.bits & MPPE_BITS) != 0) { 616 u_int rekey; 617 618 /* How many times are we going to have to re-key? */ 619 rekey = ((d->cfg.bits & MPPE_STATELESS) != 0) ? 620 numLost : (numLost / (MPPE_UPDATE_MASK + 1)); 621 if (rekey > MPPE_MAX_REKEY) { 622 log(LOG_ERR, "%s: too many (%d) packets" 623 " dropped, disabling node %p!", 624 __func__, numLost, node); 625 priv->recv.cfg.enable = 0; 626 goto failed; 627 } 628 629 /* Re-key as necessary to catch up to peer */ 630 while (d->cc != cc) { 631 if ((d->cfg.bits & MPPE_STATELESS) != 0 632 || (d->cc & MPPE_UPDATE_MASK) 633 == MPPE_UPDATE_FLAG) { 634 ng_mppc_updatekey(d->cfg.bits, 635 d->cfg.startkey, d->key, &d->rc4); 636 } 637 d->cc++; 638 } 639 640 /* Reset key (except in stateless mode, see below) */ 641 if ((d->cfg.bits & MPPE_STATELESS) == 0) 642 rc4_init(&d->rc4, d->key, KEYLEN(d->cfg.bits)); 643 } 644 #endif 645 d->cc = cc; /* skip over lost seq numbers */ 646 numLost = 0; /* act like no packets were lost */ 647 } 648 649 /* Can't decode non-sequential packets without a flushed bit */ 650 if (numLost != 0) 651 goto failed; 652 653 /* Decrypt packet */ 654 if ((header & MPPC_FLAG_ENCRYPTED) != 0) { 655 656 /* Are we not expecting encryption? */ 657 if ((d->cfg.bits & MPPE_BITS) == 0) { 658 log(LOG_ERR, "%s: rec'd unexpectedly %s packet", 659 __func__, "encrypted"); 660 goto failed; 661 } 662 663 #ifdef NETGRAPH_MPPC_ENCRYPTION 664 /* Update key if it's time (always in stateless mode) */ 665 if ((d->cfg.bits & MPPE_STATELESS) != 0 666 || (d->cc & MPPE_UPDATE_MASK) == MPPE_UPDATE_FLAG) { 667 ng_mppc_updatekey(d->cfg.bits, 668 d->cfg.startkey, d->key, &d->rc4); 669 } 670 671 /* Decrypt packet */ 672 rc4_crypt(&d->rc4, buf, buf, len); 673 #endif 674 } else { 675 676 /* Are we expecting encryption? */ 677 if ((d->cfg.bits & MPPE_BITS) != 0) { 678 log(LOG_ERR, "%s: rec'd unexpectedly %s packet", 679 __func__, "unencrypted"); 680 goto failed; 681 } 682 } 683 684 /* Update coherency count for next time (12 bit arithmetic) */ 685 d->cc++; 686 687 /* Check for unexpected compressed packet */ 688 if ((header & MPPC_FLAG_COMPRESSED) != 0 689 && (d->cfg.bits & MPPC_BIT) == 0) { 690 log(LOG_ERR, "%s: rec'd unexpectedly %s packet", 691 __func__, "compressed"); 692 failed: 693 FREE(buf, M_NETGRAPH); 694 return (EINVAL); 695 } 696 697 #ifdef NETGRAPH_MPPC_COMPRESSION 698 /* Decompress packet */ 699 if ((header & MPPC_FLAG_COMPRESSED) != 0) { 700 int flags = MPPC_MANDATORY_DECOMPRESS_FLAGS; 701 u_char *decompbuf, *source, *dest; 702 u_long sourceCnt, destCnt; 703 int decomplen, rtn; 704 705 /* Allocate a buffer for decompressed data */ 706 MALLOC(decompbuf, u_char *, MPPC_DECOMP_BUFSIZE 707 + MPPC_DECOMP_SAFETY, M_NETGRAPH, M_NOWAIT); 708 if (decompbuf == NULL) { 709 FREE(buf, M_NETGRAPH); 710 return (ENOMEM); 711 } 712 decomplen = MPPC_DECOMP_BUFSIZE; 713 714 /* Prepare to decompress */ 715 source = buf; 716 sourceCnt = len; 717 dest = decompbuf; 718 destCnt = decomplen; 719 if ((header & MPPC_FLAG_RESTART) != 0) 720 flags |= MPPC_RESTART_HISTORY; 721 722 /* Decompress */ 723 rtn = MPPC_Decompress(&source, &dest, 724 &sourceCnt, &destCnt, d->history, flags); 725 726 /* Check return value */ 727 KASSERT(rtn != MPPC_INVALID, ("%s: invalid", __func__)); 728 if ((rtn & MPPC_DEST_EXHAUSTED) != 0 729 || (rtn & MPPC_DECOMP_OK) != MPPC_DECOMP_OK) { 730 log(LOG_ERR, "%s: decomp returned 0x%x", 731 __func__, rtn); 732 FREE(decompbuf, M_NETGRAPH); 733 goto failed; 734 } 735 736 /* Replace compressed data with decompressed data */ 737 FREE(buf, M_NETGRAPH); 738 buf = decompbuf; 739 len = decomplen - destCnt; 740 } 741 #endif 742 743 /* Return result in an mbuf */ 744 *resultp = m_devget((caddr_t)buf, len, 0, NULL, NULL); 745 FREE(buf, M_NETGRAPH); 746 return (*resultp == NULL ? ENOBUFS : 0); 747 } 748 749 /* 750 * The peer has sent us a CCP ResetRequest, so reset our transmit state. 751 */ 752 static void 753 ng_mppc_reset_req(node_p node) 754 { 755 const priv_p priv = node->private; 756 struct ng_mppc_dir *const d = &priv->xmit; 757 758 #ifdef NETGRAPH_MPPC_COMPRESSION 759 if (d->history != NULL) 760 MPPC_InitCompressionHistory(d->history); 761 #endif 762 #ifdef NETGRAPH_MPPC_ENCRYPTION 763 if ((d->cfg.bits & MPPE_STATELESS) == 0) 764 rc4_init(&d->rc4, d->key, KEYLEN(d->cfg.bits)); 765 #endif 766 d->flushed = 1; 767 } 768 769 /* 770 * Generate a new encryption key 771 */ 772 static void 773 ng_mppc_getkey(const u_char *h, u_char *h2, int len) 774 { 775 static const u_char pad1[10] = 776 { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, }; 777 static const u_char pad2[10] = 778 { 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, }; 779 u_char hash[20]; 780 SHA1_CTX c; 781 int k; 782 783 bzero(&hash, sizeof(hash)); 784 SHA1Init(&c); 785 SHA1Update(&c, h, len); 786 for (k = 0; k < 4; k++) 787 SHA1Update(&c, pad1, sizeof(pad2)); 788 SHA1Update(&c, h2, len); 789 for (k = 0; k < 4; k++) 790 SHA1Update(&c, pad2, sizeof(pad2)); 791 SHA1Final(hash, &c); 792 bcopy(hash, h2, len); 793 } 794 795 /* 796 * Update the encryption key 797 */ 798 static void 799 ng_mppc_updatekey(u_int32_t bits, 800 u_char *key0, u_char *key, struct rc4_state *rc4) 801 { 802 const int keylen = KEYLEN(bits); 803 804 ng_mppc_getkey(key0, key, keylen); 805 rc4_init(rc4, key, keylen); 806 rc4_crypt(rc4, key, key, keylen); 807 if ((bits & MPPE_40) != 0) 808 bcopy(&ng_mppe_weakenkey, key, 3); 809 else if ((bits & MPPE_56) != 0) 810 bcopy(&ng_mppe_weakenkey, key, 1); 811 rc4_init(rc4, key, keylen); 812 } 813 814