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