sys/netgraph/mppc/ng_mppc.c

   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 1.6 2008/01/05 14:02:39 swildner 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 | M_ZERO);
 190         if (priv == NULL)
 191                 return (ENOMEM);
 192
 193         /* Call generic node constructor */
 194         if ((error = ng_make_node_common(&ng_mppc_typestruct, nodep))) {
 195                 FREE(priv, M_NETGRAPH);
 196                 return (error);
 197         }
 198         (*nodep)->private = priv;
 199
 200         /* Done */
 201         return (0);
 202 }
 203
 204 /*
 205  * Give our OK for a hook to be added
 206  */
 207 static int
 208 ng_mppc_newhook(node_p node, hook_p hook, const char *name)
 209 {
 210         const priv_p priv = node->private;
 211         hook_p *hookPtr;
 212
 213         /* Check hook name */
 214         if (strcmp(name, NG_MPPC_HOOK_COMP) == 0)
 215                 hookPtr = &priv->xmit.hook;
 216         else if (strcmp(name, NG_MPPC_HOOK_DECOMP) == 0)
 217                 hookPtr = &priv->recv.hook;
 218         else
 219                 return (EINVAL);
 220
 221         /* See if already connected */
 222         if (*hookPtr != NULL)
 223                 return (EISCONN);
 224
 225         /* OK */
 226         *hookPtr = hook;
 227         return (0);
 228 }
 229
 230 /*
 231  * Receive a control message
 232  */
 233 static int
 234 ng_mppc_rcvmsg(node_p node, struct ng_mesg *msg,
 235               const char *raddr, struct ng_mesg **rptr)
 236 {
 237         const priv_p priv = node->private;
 238         struct ng_mesg *resp = NULL;
 239         int error = 0;
 240
 241         switch (msg->header.typecookie) {
 242         case NGM_MPPC_COOKIE:
 243                 switch (msg->header.cmd) {
 244                 case NGM_MPPC_CONFIG_COMP:
 245                 case NGM_MPPC_CONFIG_DECOMP:
 246                     {
 247                         struct ng_mppc_config *const cfg
 248                             = (struct ng_mppc_config *)msg->data;
 249                         const int isComp =
 250                             msg->header.cmd == NGM_MPPC_CONFIG_COMP;
 251                         struct ng_mppc_dir *const d = isComp ?
 252                             &priv->xmit : &priv->recv;
 253
 254                         /* Check configuration */
 255                         if (msg->header.arglen != sizeof(*cfg))
 256                                 ERROUT(EINVAL);
 257                         if (cfg->enable) {
 258                                 if ((cfg->bits & ~MPPC_VALID_BITS) != 0)
 259                                         ERROUT(EINVAL);
 260 #ifndef NETGRAPH_MPPC_COMPRESSION
 261                                 if ((cfg->bits & MPPC_BIT) != 0)
 262                                         ERROUT(EPROTONOSUPPORT);
 263 #endif
 264 #ifndef NETGRAPH_MPPC_ENCRYPTION
 265                                 if ((cfg->bits & MPPE_BITS) != 0)
 266                                         ERROUT(EPROTONOSUPPORT);
 267 #endif
 268                         } else
 269                                 cfg->bits = 0;
 270
 271                         /* Save return address so we can send reset-req's */
 272                         if (!isComp && priv->ctrlpath != NULL) {
 273                                 FREE(priv->ctrlpath, M_NETGRAPH);
 274                                 priv->ctrlpath = NULL;
 275                         }
 276                         if (!isComp && raddr != NULL) {
 277                                 MALLOC(priv->ctrlpath, char *,
 278                                     strlen(raddr) + 1, M_NETGRAPH, M_NOWAIT);
 279                                 if (priv->ctrlpath == NULL)
 280                                         ERROUT(ENOMEM);
 281                                 strcpy(priv->ctrlpath, raddr);
 282                         }
 283
 284                         /* Configuration is OK, reset to it */
 285                         d->cfg = *cfg;
 286
 287 #ifdef NETGRAPH_MPPC_COMPRESSION
 288                         /* Initialize state buffers for compression */
 289                         if (d->history != NULL) {
 290                                 FREE(d->history, M_NETGRAPH);
 291                                 d->history = NULL;
 292                         }
 293                         if ((cfg->bits & MPPC_BIT) != 0) {
 294                                 MALLOC(d->history, u_char *,
 295                                     isComp ? MPPC_SizeOfCompressionHistory() :
 296                                     MPPC_SizeOfDecompressionHistory(),
 297                                     M_NETGRAPH, M_NOWAIT);
 298                                 if (d->history == NULL)
 299                                         ERROUT(ENOMEM);
 300                                 if (isComp)
 301                                         MPPC_InitCompressionHistory(d->history);
 302                                 else {
 303                                         MPPC_InitDecompressionHistory(
 304                                             d->history);
 305                                 }
 306                         }
 307 #endif
 308
 309 #ifdef NETGRAPH_MPPC_ENCRYPTION
 310                         /* Generate initial session keys for encryption */
 311                         if ((cfg->bits & MPPE_BITS) != 0) {
 312                                 const int keylen = KEYLEN(cfg->bits);
 313
 314                                 bcopy(cfg->startkey, d->key, keylen);
 315                                 ng_mppc_getkey(cfg->startkey, d->key, keylen);
 316                                 if ((cfg->bits & MPPE_40) != 0)
 317                                         bcopy(&ng_mppe_weakenkey, d->key, 3);
 318                                 else if ((cfg->bits & MPPE_56) != 0)
 319                                         bcopy(&ng_mppe_weakenkey, d->key, 1);
 320                                 rc4_init(&d->rc4, d->key, keylen);
 321                         }
 322 #endif
 323
 324                         /* Initialize other state */
 325                         d->cc = 0;
 326                         d->flushed = 0;
 327                         break;
 328                     }
 329
 330                 case NGM_MPPC_RESETREQ:
 331                         ng_mppc_reset_req(node);
 332                         break;
 333
 334                 default:
 335                         error = EINVAL;
 336                         break;
 337                 }
 338                 break;
 339         default:
 340                 error = EINVAL;
 341                 break;
 342         }
 343         if (rptr)
 344                 *rptr = resp;
 345         else if (resp)
 346                 FREE(resp, M_NETGRAPH);
 347
 348 done:
 349         FREE(msg, M_NETGRAPH);
 350         return (error);
 351 }
 352
 353 /*
 354  * Receive incoming data on our hook.
 355  */
 356 static int
 357 ng_mppc_rcvdata(hook_p hook, struct mbuf *m, meta_p meta)
 358 {
 359         const node_p node = hook->node;
 360         const priv_p priv = node->private;
 361         struct mbuf *out;
 362         int error;
 363
 364         /* Compress and/or encrypt */
 365         if (hook == priv->xmit.hook) {
 366                 if (!priv->xmit.cfg.enable) {
 367                         NG_FREE_DATA(m, meta);
 368                         return (ENXIO);
 369                 }
 370                 if ((error = ng_mppc_compress(node, m, &out)) != 0) {
 371                         NG_FREE_DATA(m, meta);
 372                         return(error);
 373                 }
 374                 m_freem(m);
 375                 NG_SEND_DATA(error, priv->xmit.hook, out, meta);
 376                 return (error);
 377         }
 378
 379         /* Decompress and/or decrypt */
 380         if (hook == priv->recv.hook) {
 381                 if (!priv->recv.cfg.enable) {
 382                         NG_FREE_DATA(m, meta);
 383                         return (ENXIO);
 384                 }
 385                 if ((error = ng_mppc_decompress(node, m, &out)) != 0) {
 386                         NG_FREE_DATA(m, meta);
 387                         if (error == EINVAL && priv->ctrlpath != NULL) {
 388                                 struct ng_mesg *msg;
 389
 390                                 /* Need to send a reset-request */
 391                                 NG_MKMESSAGE(msg, NGM_MPPC_COOKIE,
 392                                     NGM_MPPC_RESETREQ, 0, M_NOWAIT);
 393                                 if (msg == NULL)
 394                                         return (error);
 395                                 ng_send_msg(node, msg, priv->ctrlpath, NULL);
 396                         }
 397                         return (error);
 398                 }
 399                 m_freem(m);
 400                 NG_SEND_DATA(error, priv->recv.hook, out, meta);
 401                 return (error);
 402         }
 403
 404         /* Oops */
 405         panic("%s: unknown hook", __func__);
 406 }
 407
 408 /*
 409  * Destroy node
 410  */
 411 static int
 412 ng_mppc_rmnode(node_p node)
 413 {
 414         const priv_p priv = node->private;
 415
 416         /* Take down netgraph node */
 417         node->flags |= NG_INVALID;
 418         ng_cutlinks(node);
 419         ng_unname(node);
 420         if (priv->ctrlpath != NULL)
 421                 FREE(priv->ctrlpath, M_NETGRAPH);
 422 #ifdef NETGRAPH_MPPC_COMPRESSION
 423         if (priv->xmit.history != NULL)
 424                 FREE(priv->xmit.history, M_NETGRAPH);
 425         if (priv->recv.history != NULL)
 426                 FREE(priv->recv.history, M_NETGRAPH);
 427 #endif
 428         bzero(priv, sizeof(*priv));
 429         FREE(priv, M_NETGRAPH);
 430         node->private = NULL;
 431         ng_unref(node);         /* let the node escape */
 432         return (0);
 433 }
 434
 435 /*
 436  * Hook disconnection
 437  */
 438 static int
 439 ng_mppc_disconnect(hook_p hook)
 440 {
 441         const node_p node = hook->node;
 442         const priv_p priv = node->private;
 443
 444         /* Zero out hook pointer */
 445         if (hook == priv->xmit.hook)
 446                 priv->xmit.hook = NULL;
 447         if (hook == priv->recv.hook)
 448                 priv->recv.hook = NULL;
 449
 450         /* Go away if no longer connected */
 451         if (node->numhooks == 0)
 452                 ng_rmnode(node);
 453         return (0);
 454 }
 455
 456 /************************************************************************
 457                         HELPER STUFF
 458  ************************************************************************/
 459
 460 /*
 461  * Compress/encrypt a packet and put the result in a new mbuf at *resultp.
 462  * The original mbuf is not free'd.
 463  */
 464 static int
 465 ng_mppc_compress(node_p node, struct mbuf *m, struct mbuf **resultp)
 466 {
 467         const priv_p priv = node->private;
 468         struct ng_mppc_dir *const d = &priv->xmit;
 469         u_char *inbuf, *outbuf;
 470         int outlen, inlen;
 471         u_int16_t header;
 472
 473         /* Initialize */
 474         *resultp = NULL;
 475         header = d->cc;
 476         if (d->flushed) {
 477                 header |= MPPC_FLAG_FLUSHED;
 478                 d->flushed = 0;
 479         }
 480
 481         /* Work with contiguous regions of memory */
 482         inlen = m->m_pkthdr.len;
 483         MALLOC(inbuf, u_char *, inlen, M_NETGRAPH, M_NOWAIT);
 484         if (inbuf == NULL)
 485                 return (ENOMEM);
 486         m_copydata(m, 0, inlen, (caddr_t)inbuf);
 487         if ((d->cfg.bits & MPPC_BIT) != 0)
 488                 outlen = MPPC_MAX_BLOWUP(inlen);
 489         else
 490                 outlen = MPPC_HDRLEN + inlen;
 491         MALLOC(outbuf, u_char *, outlen, M_NETGRAPH, M_NOWAIT);
 492         if (outbuf == NULL) {
 493                 FREE(inbuf, M_NETGRAPH);
 494                 return (ENOMEM);
 495         }
 496
 497         /* Compress "inbuf" into "outbuf" (if compression enabled) */
 498 #ifdef NETGRAPH_MPPC_COMPRESSION
 499         if ((d->cfg.bits & MPPC_BIT) != 0) {
 500                 u_short flags = MPPC_MANDATORY_COMPRESS_FLAGS;
 501                 u_char *source, *dest;
 502                 u_long sourceCnt, destCnt;
 503                 int rtn;
 504
 505                 /* Prepare to compress */
 506                 source = inbuf;
 507                 sourceCnt = inlen;
 508                 dest = outbuf + MPPC_HDRLEN;
 509                 destCnt = outlen - MPPC_HDRLEN;
 510                 if ((d->cfg.bits & MPPE_STATELESS) == 0)
 511                         flags |= MPPC_SAVE_HISTORY;
 512
 513                 /* Compress */
 514                 rtn = MPPC_Compress(&source, &dest, &sourceCnt,
 515                         &destCnt, d->history, flags, 0);
 516
 517                 /* Check return value */
 518                 KASSERT(rtn != MPPC_INVALID, ("%s: invalid", __func__));
 519                 if ((rtn & MPPC_EXPANDED) == 0
 520                     && (rtn & MPPC_COMP_OK) == MPPC_COMP_OK) {
 521                         outlen -= destCnt;
 522                         header |= MPPC_FLAG_COMPRESSED;
 523                         if ((rtn & MPPC_RESTART_HISTORY) != 0)
 524                                 header |= MPPC_FLAG_RESTART;
 525                 }
 526                 d->flushed = (rtn & MPPC_EXPANDED) != 0
 527                     || (flags & MPPC_SAVE_HISTORY) == 0;
 528         }
 529 #endif
 530
 531         /* If we did not compress this packet, copy it to output buffer */
 532         if ((header & MPPC_FLAG_COMPRESSED) == 0) {
 533                 bcopy(inbuf, outbuf + MPPC_HDRLEN, inlen);
 534                 outlen = MPPC_HDRLEN + inlen;
 535         }
 536         FREE(inbuf, M_NETGRAPH);
 537
 538         /* Always set the flushed bit in stateless mode */
 539         if ((d->cfg.bits & MPPE_STATELESS) != 0)
 540                 header |= MPPC_FLAG_FLUSHED;
 541
 542         /* Now encrypt packet (if encryption enabled) */
 543 #ifdef NETGRAPH_MPPC_ENCRYPTION
 544         if ((d->cfg.bits & MPPE_BITS) != 0) {
 545
 546                 /* Set header bits; need to reset key if we say we did */
 547                 header |= MPPC_FLAG_ENCRYPTED;
 548                 if ((header & MPPC_FLAG_FLUSHED) != 0)
 549                         rc4_init(&d->rc4, d->key, KEYLEN(d->cfg.bits));
 550
 551                 /* Update key if it's time */
 552                 if ((d->cfg.bits & MPPE_STATELESS) != 0
 553                     || (d->cc & MPPE_UPDATE_MASK) == MPPE_UPDATE_FLAG) {
 554                           ng_mppc_updatekey(d->cfg.bits,
 555                               d->cfg.startkey, d->key, &d->rc4);
 556                 }
 557
 558                 /* Encrypt packet */
 559                 rc4_crypt(&d->rc4, outbuf + MPPC_HDRLEN,
 560                         outbuf + MPPC_HDRLEN, outlen - MPPC_HDRLEN);
 561         }
 562 #endif
 563
 564         /* Update sequence number */
 565         d->cc++;
 566
 567         /* Install header */
 568         *((u_int16_t *)outbuf) = htons(header);
 569
 570         /* Return packet in an mbuf */
 571         *resultp = m_devget((caddr_t)outbuf, outlen, 0, NULL, NULL);
 572         FREE(outbuf, M_NETGRAPH);
 573         return (*resultp == NULL ? ENOBUFS : 0);
 574 }
 575
 576 /*
 577  * Decompress/decrypt packet and put the result in a new mbuf at *resultp.
 578  * The original mbuf is not free'd.
 579  */
 580 static int
 581 ng_mppc_decompress(node_p node, struct mbuf *m, struct mbuf **resultp)
 582 {
 583         const priv_p priv = node->private;
 584         struct ng_mppc_dir *const d = &priv->recv;
 585         u_int16_t header, cc;
 586         u_int numLost;
 587         u_char *buf;
 588         int len;
 589
 590         /* Pull off header */
 591         if (m->m_pkthdr.len < MPPC_HDRLEN)
 592                 return (EINVAL);
 593         m_copydata(m, 0, MPPC_HDRLEN, (caddr_t)&header);
 594         header = ntohs(header);
 595         cc = (header & MPPC_CCOUNT_MASK);
 596
 597         /* Copy payload into a contiguous region of memory */
 598         len = m->m_pkthdr.len - MPPC_HDRLEN;
 599         MALLOC(buf, u_char *, len, M_NETGRAPH, M_NOWAIT);
 600         if (buf == NULL)
 601                 return (ENOMEM);
 602         m_copydata(m, MPPC_HDRLEN, len, (caddr_t)buf);
 603
 604         /* Check for an unexpected jump in the sequence number */
 605         numLost = ((cc - d->cc) & MPPC_CCOUNT_MASK);
 606
 607         /* If flushed bit set, we can always handle packet */
 608         if ((header & MPPC_FLAG_FLUSHED) != 0) {
 609 #ifdef NETGRAPH_MPPC_COMPRESSION
 610                 if (d->history != NULL)
 611                         MPPC_InitDecompressionHistory(d->history);
 612 #endif
 613 #ifdef NETGRAPH_MPPC_ENCRYPTION
 614                 if ((d->cfg.bits & MPPE_BITS) != 0) {
 615                         u_int rekey;
 616
 617                         /* How many times are we going to have to re-key? */
 618                         rekey = ((d->cfg.bits & MPPE_STATELESS) != 0) ?
 619                             numLost : (numLost / (MPPE_UPDATE_MASK + 1));
 620                         if (rekey > MPPE_MAX_REKEY) {
 621                                 log(LOG_ERR, "%s: too many (%d) packets"
 622                                     " dropped, disabling node %p!",
 623                                     __func__, numLost, node);
 624                                 priv->recv.cfg.enable = 0;
 625                                 goto failed;
 626                         }
 627
 628                         /* Re-key as necessary to catch up to peer */
 629                         while (d->cc != cc) {
 630                                 if ((d->cfg.bits & MPPE_STATELESS) != 0
 631                                     || (d->cc & MPPE_UPDATE_MASK)
 632                                       == MPPE_UPDATE_FLAG) {
 633                                         ng_mppc_updatekey(d->cfg.bits,
 634                                             d->cfg.startkey, d->key, &d->rc4);
 635                                 }
 636                                 d->cc++;
 637                         }
 638
 639                         /* Reset key (except in stateless mode, see below) */
 640                         if ((d->cfg.bits & MPPE_STATELESS) == 0)
 641                                 rc4_init(&d->rc4, d->key, KEYLEN(d->cfg.bits));
 642                 }
 643 #endif
 644                 d->cc = cc;             /* skip over lost seq numbers */
 645                 numLost = 0;            /* act like no packets were lost */
 646         }
 647
 648         /* Can't decode non-sequential packets without a flushed bit */
 649         if (numLost != 0)
 650                 goto failed;
 651
 652         /* Decrypt packet */
 653         if ((header & MPPC_FLAG_ENCRYPTED) != 0) {
 654
 655                 /* Are we not expecting encryption? */
 656                 if ((d->cfg.bits & MPPE_BITS) == 0) {
 657                         log(LOG_ERR, "%s: rec'd unexpectedly %s packet",
 658                                 __func__, "encrypted");
 659                         goto failed;
 660                 }
 661
 662 #ifdef NETGRAPH_MPPC_ENCRYPTION
 663                 /* Update key if it's time (always in stateless mode) */
 664                 if ((d->cfg.bits & MPPE_STATELESS) != 0
 665                     || (d->cc & MPPE_UPDATE_MASK) == MPPE_UPDATE_FLAG) {
 666                         ng_mppc_updatekey(d->cfg.bits,
 667                             d->cfg.startkey, d->key, &d->rc4);
 668                 }
 669
 670                 /* Decrypt packet */
 671                 rc4_crypt(&d->rc4, buf, buf, len);
 672 #endif
 673         } else {
 674
 675                 /* Are we expecting encryption? */
 676                 if ((d->cfg.bits & MPPE_BITS) != 0) {
 677                         log(LOG_ERR, "%s: rec'd unexpectedly %s packet",
 678                                 __func__, "unencrypted");
 679                         goto failed;
 680                 }
 681         }
 682
 683         /* Update coherency count for next time (12 bit arithmetic) */
 684         d->cc++;
 685
 686         /* Check for unexpected compressed packet */
 687         if ((header & MPPC_FLAG_COMPRESSED) != 0
 688             && (d->cfg.bits & MPPC_BIT) == 0) {
 689                 log(LOG_ERR, "%s: rec'd unexpectedly %s packet",
 690                         __func__, "compressed");
 691 failed:
 692                 FREE(buf, M_NETGRAPH);
 693                 return (EINVAL);
 694         }
 695
 696 #ifdef NETGRAPH_MPPC_COMPRESSION
 697         /* Decompress packet */
 698         if ((header & MPPC_FLAG_COMPRESSED) != 0) {
 699                 int flags = MPPC_MANDATORY_DECOMPRESS_FLAGS;
 700                 u_char *decompbuf, *source, *dest;
 701                 u_long sourceCnt, destCnt;
 702                 int decomplen, rtn;
 703
 704                 /* Allocate a buffer for decompressed data */
 705                 MALLOC(decompbuf, u_char *, MPPC_DECOMP_BUFSIZE
 706                     + MPPC_DECOMP_SAFETY, M_NETGRAPH, M_NOWAIT);
 707                 if (decompbuf == NULL) {
 708                         FREE(buf, M_NETGRAPH);
 709                         return (ENOMEM);
 710                 }
 711                 decomplen = MPPC_DECOMP_BUFSIZE;
 712
 713                 /* Prepare to decompress */
 714                 source = buf;
 715                 sourceCnt = len;
 716                 dest = decompbuf;
 717                 destCnt = decomplen;
 718                 if ((header & MPPC_FLAG_RESTART) != 0)
 719                         flags |= MPPC_RESTART_HISTORY;
 720
 721                 /* Decompress */
 722                 rtn = MPPC_Decompress(&source, &dest,
 723                         &sourceCnt, &destCnt, d->history, flags);
 724
 725                 /* Check return value */
 726                 KASSERT(rtn != MPPC_INVALID, ("%s: invalid", __func__));
 727                 if ((rtn & MPPC_DEST_EXHAUSTED) != 0
 728                     || (rtn & MPPC_DECOMP_OK) != MPPC_DECOMP_OK) {
 729                         log(LOG_ERR, "%s: decomp returned 0x%x",
 730                             __func__, rtn);
 731                         FREE(decompbuf, M_NETGRAPH);
 732                         goto failed;
 733                 }
 734
 735                 /* Replace compressed data with decompressed data */
 736                 FREE(buf, M_NETGRAPH);
 737                 buf = decompbuf;
 738                 len = decomplen - destCnt;
 739         }
 740 #endif
 741
 742         /* Return result in an mbuf */
 743         *resultp = m_devget((caddr_t)buf, len, 0, NULL, NULL);
 744         FREE(buf, M_NETGRAPH);
 745         return (*resultp == NULL ? ENOBUFS : 0);
 746 }
 747
 748 /*
 749  * The peer has sent us a CCP ResetRequest, so reset our transmit state.
 750  */
 751 static void
 752 ng_mppc_reset_req(node_p node)
 753 {
 754         const priv_p priv = node->private;
 755         struct ng_mppc_dir *const d = &priv->xmit;
 756
 757 #ifdef NETGRAPH_MPPC_COMPRESSION
 758         if (d->history != NULL)
 759                 MPPC_InitCompressionHistory(d->history);
 760 #endif
 761 #ifdef NETGRAPH_MPPC_ENCRYPTION
 762         if ((d->cfg.bits & MPPE_STATELESS) == 0)
 763                 rc4_init(&d->rc4, d->key, KEYLEN(d->cfg.bits));
 764 #endif
 765         d->flushed = 1;
 766 }
 767
 768 /*
 769  * Generate a new encryption key
 770  */
 771 static void
 772 ng_mppc_getkey(const u_char *h, u_char *h2, int len)
 773 {
 774         static const u_char pad1[10] =
 775             { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, };
 776         static const u_char pad2[10] =
 777             { 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, };
 778         u_char hash[20];
 779         SHA1_CTX c;
 780         int k;
 781
 782         bzero(&hash, sizeof(hash));
 783         SHA1Init(&c);
 784         SHA1Update(&c, h, len);
 785         for (k = 0; k < 4; k++)
 786                 SHA1Update(&c, pad1, sizeof(pad2));
 787         SHA1Update(&c, h2, len);
 788         for (k = 0; k < 4; k++)
 789                 SHA1Update(&c, pad2, sizeof(pad2));
 790         SHA1Final(hash, &c);
 791         bcopy(hash, h2, len);
 792 }
 793
 794 /*
 795  * Update the encryption key
 796  */
 797 static void
 798 ng_mppc_updatekey(u_int32_t bits,
 799         u_char *key0, u_char *key, struct rc4_state *rc4)
 800 {
 801         const int keylen = KEYLEN(bits);
 802
 803         ng_mppc_getkey(key0, key, keylen);
 804         rc4_init(rc4, key, keylen);
 805         rc4_crypt(rc4, key, key, keylen);
 806         if ((bits & MPPE_40) != 0)
 807                 bcopy(&ng_mppe_weakenkey, key, 3);
 808         else if ((bits & MPPE_56) != 0)
 809                 bcopy(&ng_mppe_weakenkey, key, 1);
 810         rc4_init(rc4, key, keylen);
 811 }
 812