The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/netgraph/ng_mppc.c

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    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  * $FreeBSD$
   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 <netgraph/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         MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH, M_NOWAIT);
  189         if (priv == NULL)
  190                 return (ENOMEM);
  191         bzero(priv, sizeof(*priv));
  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", __FUNCTION__);
  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", __FUNCTION__));
  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         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                                     __FUNCTION__, 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                                 __FUNCTION__, "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                                 __FUNCTION__, "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                         __FUNCTION__, "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", __FUNCTION__));
  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                             __FUNCTION__, 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 

Cache object: fc3a7111663097d34b8862f429c2f4ed


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