ng_mppc.c revision 139823 
1/*
2 * ng_mppc.c
3 */
4
5/*-
6 * Copyright (c) 1996-2000 Whistle Communications, Inc.
7 * All rights reserved.
8 *
9 * Subject to the following obligations and disclaimer of warranty, use and
10 * redistribution of this software, in source or object code forms, with or
11 * without modifications are expressly permitted by Whistle Communications;
12 * provided, however, that:
13 * 1. Any and all reproductions of the source or object code must include the
14 *    copyright notice above and the following disclaimer of warranties; and
15 * 2. No rights are granted, in any manner or form, to use Whistle
16 *    Communications, Inc. trademarks, including the mark "WHISTLE
17 *    COMMUNICATIONS" on advertising, endorsements, or otherwise except as
18 *    such appears in the above copyright notice or in the software.
19 *
20 * THIS SOFTWARE IS BEING PROVIDED BY WHISTLE COMMUNICATIONS "AS IS", AND
21 * TO THE MAXIMUM EXTENT PERMITTED BY LAW, WHISTLE COMMUNICATIONS MAKES NO
22 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING THIS SOFTWARE,
23 * INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED WARRANTIES OF
24 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT.
25 * WHISTLE COMMUNICATIONS DOES NOT WARRANT, GUARANTEE, OR MAKE ANY
26 * REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS OF THE USE OF THIS
27 * SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, RELIABILITY OR OTHERWISE.
28 * IN NO EVENT SHALL WHISTLE COMMUNICATIONS BE LIABLE FOR ANY DAMAGES
29 * RESULTING FROM OR ARISING OUT OF ANY USE OF THIS SOFTWARE, INCLUDING
30 * WITHOUT LIMITATION, ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY,
31 * PUNITIVE, OR CONSEQUENTIAL DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR
32 * SERVICES, LOSS OF USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY
33 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
34 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
35 * THIS SOFTWARE, EVEN IF WHISTLE COMMUNICATIONS IS ADVISED OF THE POSSIBILITY
36 * OF SUCH DAMAGE.
37 *
38 * Author: Archie Cobbs <archie@freebsd.org>
39 *
40 * $Whistle: ng_mppc.c,v 1.4 1999/11/25 00:10:12 archie Exp $
41 * $FreeBSD: head/sys/netgraph/ng_mppc.c 139823 2005-01-07 01:45:51Z imp $
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/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 NG_SEPARATE_MALLOC
70MALLOC_DEFINE(M_NETGRAPH_MPPC, "netgraph_mppc", "netgraph mppc node ");
71#else
72#define M_NETGRAPH_MPPC M_NETGRAPH
73#endif
74
75#ifdef NETGRAPH_MPPC_COMPRESSION
76/* XXX this file doesn't exist yet, but hopefully someday it will... */
77#include <net/mppc.h>
78#endif
79#ifdef NETGRAPH_MPPC_ENCRYPTION
80#include <crypto/rc4/rc4.h>
81#endif
82#include <crypto/sha1.h>
83
84/* Decompression blowup */
85#define MPPC_DECOMP_BUFSIZE	8092            /* allocate buffer this big */
86#define MPPC_DECOMP_SAFETY	100             /*   plus this much margin */
87
88/* MPPC/MPPE header length */
89#define MPPC_HDRLEN		2
90
91/* Key length */
92#define KEYLEN(b)		(((b) & MPPE_128) ? 16 : 8)
93
94/*
95 * When packets are lost with MPPE, we may have to re-key arbitrarily
96 * many times to 'catch up' to the new jumped-ahead sequence number.
97 * Since this can be expensive, we pose a limit on how many re-keyings
98 * we will do at one time to avoid a possible D.O.S. vulnerability.
99 * This should instead be a configurable parameter.
100 */
101#define MPPE_MAX_REKEY		1000
102
103/* MPPC packet header bits */
104#define MPPC_FLAG_FLUSHED	0x8000		/* xmitter reset state */
105#define MPPC_FLAG_RESTART	0x4000		/* compress history restart */
106#define MPPC_FLAG_COMPRESSED	0x2000		/* packet is compresed */
107#define MPPC_FLAG_ENCRYPTED	0x1000		/* packet is encrypted */
108#define MPPC_CCOUNT_MASK	0x0fff		/* sequence number mask */
109
110#define MPPE_UPDATE_MASK	0xff		/* coherency count when we're */
111#define MPPE_UPDATE_FLAG	0xff		/*   supposed to update key */
112
113#define MPPC_COMP_OK		0x05
114#define MPPC_DECOMP_OK		0x05
115
116/* Per direction info */
117struct ng_mppc_dir {
118	struct ng_mppc_config	cfg;		/* configuration */
119	hook_p			hook;		/* netgraph hook */
120	u_int16_t		cc:12;		/* coherency count */
121	u_char			flushed;	/* clean history (xmit only) */
122#ifdef NETGRAPH_MPPC_COMPRESSION
123	u_char			*history;	/* compression history */
124#endif
125#ifdef NETGRAPH_MPPC_ENCRYPTION
126	u_char			key[MPPE_KEY_LEN];	/* session key */
127	struct rc4_state	rc4;			/* rc4 state */
128#endif
129};
130
131/* Node private data */
132struct ng_mppc_private {
133	struct ng_mppc_dir	xmit;		/* compress/encrypt config */
134	struct ng_mppc_dir	recv;		/* decompress/decrypt config */
135	ng_ID_t			ctrlnode;	/* path to controlling node */
136};
137typedef struct ng_mppc_private *priv_p;
138
139/* Netgraph node methods */
140static ng_constructor_t	ng_mppc_constructor;
141static ng_rcvmsg_t	ng_mppc_rcvmsg;
142static ng_shutdown_t	ng_mppc_shutdown;
143static ng_newhook_t	ng_mppc_newhook;
144static ng_rcvdata_t	ng_mppc_rcvdata;
145static ng_disconnect_t	ng_mppc_disconnect;
146
147/* Helper functions */
148static int	ng_mppc_compress(node_p node,
149			struct mbuf *m, struct mbuf **resultp);
150static int	ng_mppc_decompress(node_p node,
151			struct mbuf *m, struct mbuf **resultp);
152static void	ng_mppc_getkey(const u_char *h, u_char *h2, int len);
153static void	ng_mppc_updatekey(u_int32_t bits,
154			u_char *key0, u_char *key, struct rc4_state *rc4);
155static void	ng_mppc_reset_req(node_p node);
156
157/* Node type descriptor */
158static struct ng_type ng_mppc_typestruct = {
159	.version =	NG_ABI_VERSION,
160	.name =		NG_MPPC_NODE_TYPE,
161	.constructor =	ng_mppc_constructor,
162	.rcvmsg =	ng_mppc_rcvmsg,
163	.shutdown =	ng_mppc_shutdown,
164	.newhook =	ng_mppc_newhook,
165	.rcvdata =	ng_mppc_rcvdata,
166	.disconnect =	ng_mppc_disconnect,
167};
168NETGRAPH_INIT(mppc, &ng_mppc_typestruct);
169
170#ifdef NETGRAPH_MPPC_ENCRYPTION
171/* Depend on separate rc4 module */
172MODULE_DEPEND(ng_mppc, rc4, 1, 1, 1);
173#endif
174
175/* Fixed bit pattern to weaken keysize down to 40 or 56 bits */
176static const u_char ng_mppe_weakenkey[3] = { 0xd1, 0x26, 0x9e };
177
178#define ERROUT(x)	do { error = (x); goto done; } while (0)
179
180/************************************************************************
181			NETGRAPH NODE STUFF
182 ************************************************************************/
183
184/*
185 * Node type constructor
186 */
187static int
188ng_mppc_constructor(node_p node)
189{
190	priv_p priv;
191
192	/* Allocate private structure */
193	MALLOC(priv, priv_p, sizeof(*priv), M_NETGRAPH_MPPC, M_NOWAIT | M_ZERO);
194	if (priv == NULL)
195		return (ENOMEM);
196
197	NG_NODE_SET_PRIVATE(node, priv);
198
199	/* Done */
200	return (0);
201}
202
203/*
204 * Give our OK for a hook to be added
205 */
206static int
207ng_mppc_newhook(node_p node, hook_p hook, const char *name)
208{
209	const priv_p priv = NG_NODE_PRIVATE(node);
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 */
232static int
233ng_mppc_rcvmsg(node_p node, item_p item, hook_p lasthook)
234{
235	const priv_p priv = NG_NODE_PRIVATE(node);
236	struct ng_mesg *resp = NULL;
237	int error = 0;
238	struct ng_mesg *msg;
239
240	NGI_GET_MSG(item, msg);
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)
273				priv->ctrlnode = NGI_RETADDR(item);
274
275			/* Configuration is OK, reset to it */
276			d->cfg = *cfg;
277
278#ifdef NETGRAPH_MPPC_COMPRESSION
279			/* Initialize state buffers for compression */
280			if (d->history != NULL) {
281				FREE(d->history, M_NETGRAPH_MPPC);
282				d->history = NULL;
283			}
284			if ((cfg->bits & MPPC_BIT) != 0) {
285				MALLOC(d->history, u_char *,
286				    isComp ? MPPC_SizeOfCompressionHistory() :
287				    MPPC_SizeOfDecompressionHistory(),
288				    M_NETGRAPH_MPPC, M_NOWAIT);
289				if (d->history == NULL)
290					ERROUT(ENOMEM);
291				if (isComp)
292					MPPC_InitCompressionHistory(d->history);
293				else {
294					MPPC_InitDecompressionHistory(
295					    d->history);
296				}
297			}
298#endif
299
300#ifdef NETGRAPH_MPPC_ENCRYPTION
301			/* Generate initial session keys for encryption */
302			if ((cfg->bits & MPPE_BITS) != 0) {
303				const int keylen = KEYLEN(cfg->bits);
304
305				bcopy(cfg->startkey, d->key, keylen);
306				ng_mppc_getkey(cfg->startkey, d->key, keylen);
307				if ((cfg->bits & MPPE_40) != 0)
308					bcopy(&ng_mppe_weakenkey, d->key, 3);
309				else if ((cfg->bits & MPPE_56) != 0)
310					bcopy(&ng_mppe_weakenkey, d->key, 1);
311				rc4_init(&d->rc4, d->key, keylen);
312			}
313#endif
314
315			/* Initialize other state */
316			d->cc = 0;
317			d->flushed = 0;
318			break;
319		    }
320
321		case NGM_MPPC_RESETREQ:
322			ng_mppc_reset_req(node);
323			break;
324
325		default:
326			error = EINVAL;
327			break;
328		}
329		break;
330	default:
331		error = EINVAL;
332		break;
333	}
334done:
335	NG_RESPOND_MSG(error, node, item, resp);
336	NG_FREE_MSG(msg);
337	return (error);
338}
339
340/*
341 * Receive incoming data on our hook.
342 */
343static int
344ng_mppc_rcvdata(hook_p hook, item_p item)
345{
346	const node_p node = NG_HOOK_NODE(hook);
347	const priv_p priv = NG_NODE_PRIVATE(node);
348	struct mbuf *out;
349	int error;
350	struct mbuf *m;
351
352	NGI_GET_M(item, m);
353	/* Compress and/or encrypt */
354	if (hook == priv->xmit.hook) {
355		if (!priv->xmit.cfg.enable) {
356			NG_FREE_M(m);
357			NG_FREE_ITEM(item);
358			return (ENXIO);
359		}
360		if ((error = ng_mppc_compress(node, m, &out)) != 0) {
361			NG_FREE_M(m);
362			NG_FREE_ITEM(item);
363			return(error);
364		}
365		NG_FREE_M(m);
366		NG_FWD_NEW_DATA(error, item, priv->xmit.hook, out);
367		return (error);
368	}
369
370	/* Decompress and/or decrypt */
371	if (hook == priv->recv.hook) {
372		if (!priv->recv.cfg.enable) {
373			NG_FREE_M(m);
374			NG_FREE_ITEM(item);
375			return (ENXIO);
376		}
377		if ((error = ng_mppc_decompress(node, m, &out)) != 0) {
378			NG_FREE_M(m);
379			NG_FREE_ITEM(item);
380			if (error == EINVAL && priv->ctrlnode != 0) {
381				struct ng_mesg *msg;
382
383				/* Need to send a reset-request */
384				NG_MKMESSAGE(msg, NGM_MPPC_COOKIE,
385				    NGM_MPPC_RESETREQ, 0, M_NOWAIT);
386				if (msg == NULL)
387					return (error);
388				NG_SEND_MSG_ID(error, node, msg,
389					priv->ctrlnode, 0);
390			}
391			return (error);
392		}
393		NG_FREE_M(m);
394		NG_FWD_NEW_DATA(error, item, priv->recv.hook, out);
395		return (error);
396	}
397
398	/* Oops */
399	panic("%s: unknown hook", __func__);
400#ifdef RESTARTABLE_PANICS
401	return (EINVAL);
402#endif
403}
404
405/*
406 * Destroy node
407 */
408static int
409ng_mppc_shutdown(node_p node)
410{
411	const priv_p priv = NG_NODE_PRIVATE(node);
412
413	/* Take down netgraph node */
414#ifdef NETGRAPH_MPPC_COMPRESSION
415	if (priv->xmit.history != NULL)
416		FREE(priv->xmit.history, M_NETGRAPH_MPPC);
417	if (priv->recv.history != NULL)
418		FREE(priv->recv.history, M_NETGRAPH_MPPC);
419#endif
420	bzero(priv, sizeof(*priv));
421	FREE(priv, M_NETGRAPH_MPPC);
422	NG_NODE_SET_PRIVATE(node, NULL);
423	NG_NODE_UNREF(node);		/* let the node escape */
424	return (0);
425}
426
427/*
428 * Hook disconnection
429 */
430static int
431ng_mppc_disconnect(hook_p hook)
432{
433	const node_p node = NG_HOOK_NODE(hook);
434	const priv_p priv = NG_NODE_PRIVATE(node);
435
436	/* Zero out hook pointer */
437	if (hook == priv->xmit.hook)
438		priv->xmit.hook = NULL;
439	if (hook == priv->recv.hook)
440		priv->recv.hook = NULL;
441
442	/* Go away if no longer connected */
443	if ((NG_NODE_NUMHOOKS(node) == 0)
444	&& NG_NODE_IS_VALID(node))
445		ng_rmnode_self(node);
446	return (0);
447}
448
449/************************************************************************
450			HELPER STUFF
451 ************************************************************************/
452
453/*
454 * Compress/encrypt a packet and put the result in a new mbuf at *resultp.
455 * The original mbuf is not free'd.
456 */
457static int
458ng_mppc_compress(node_p node, struct mbuf *m, struct mbuf **resultp)
459{
460	const priv_p priv = NG_NODE_PRIVATE(node);
461	struct ng_mppc_dir *const d = &priv->xmit;
462	u_char *inbuf, *outbuf;
463	int outlen, inlen;
464	u_int16_t header;
465
466	/* Initialize */
467	*resultp = NULL;
468	header = d->cc;
469	if (d->flushed) {
470		header |= MPPC_FLAG_FLUSHED;
471		d->flushed = 0;
472	}
473
474	/* Work with contiguous regions of memory */
475	inlen = m->m_pkthdr.len;
476	MALLOC(inbuf, u_char *, inlen, M_NETGRAPH_MPPC, M_NOWAIT);
477	if (inbuf == NULL)
478		return (ENOMEM);
479	m_copydata(m, 0, inlen, (caddr_t)inbuf);
480	if ((d->cfg.bits & MPPC_BIT) != 0)
481		outlen = MPPC_MAX_BLOWUP(inlen);
482	else
483		outlen = MPPC_HDRLEN + inlen;
484	MALLOC(outbuf, u_char *, outlen, M_NETGRAPH_MPPC, M_NOWAIT);
485	if (outbuf == NULL) {
486		FREE(inbuf, M_NETGRAPH_MPPC);
487		return (ENOMEM);
488	}
489
490	/* Compress "inbuf" into "outbuf" (if compression enabled) */
491#ifdef NETGRAPH_MPPC_COMPRESSION
492	if ((d->cfg.bits & MPPC_BIT) != 0) {
493		u_short flags = MPPC_MANDATORY_COMPRESS_FLAGS;
494		u_char *source, *dest;
495		u_long sourceCnt, destCnt;
496		int rtn;
497
498		/* Prepare to compress */
499		source = inbuf;
500		sourceCnt = inlen;
501		dest = outbuf + MPPC_HDRLEN;
502		destCnt = outlen - MPPC_HDRLEN;
503		if ((d->cfg.bits & MPPE_STATELESS) == 0)
504			flags |= MPPC_SAVE_HISTORY;
505
506		/* Compress */
507		rtn = MPPC_Compress(&source, &dest, &sourceCnt,
508			&destCnt, d->history, flags, 0);
509
510		/* Check return value */
511		KASSERT(rtn != MPPC_INVALID, ("%s: invalid", __func__));
512		if ((rtn & MPPC_EXPANDED) == 0
513		    && (rtn & MPPC_COMP_OK) == MPPC_COMP_OK) {
514			outlen -= destCnt;
515			header |= MPPC_FLAG_COMPRESSED;
516			if ((rtn & MPPC_RESTART_HISTORY) != 0)
517				header |= MPPC_FLAG_RESTART;
518		}
519		d->flushed = (rtn & MPPC_EXPANDED) != 0
520		    || (flags & MPPC_SAVE_HISTORY) == 0;
521	}
522#endif
523
524	/* If we did not compress this packet, copy it to output buffer */
525	if ((header & MPPC_FLAG_COMPRESSED) == 0) {
526		bcopy(inbuf, outbuf + MPPC_HDRLEN, inlen);
527		outlen = MPPC_HDRLEN + inlen;
528	}
529	FREE(inbuf, M_NETGRAPH_MPPC);
530
531	/* Always set the flushed bit in stateless mode */
532	if ((d->cfg.bits & MPPE_STATELESS) != 0)
533		header |= MPPC_FLAG_FLUSHED;
534
535	/* Now encrypt packet (if encryption enabled) */
536#ifdef NETGRAPH_MPPC_ENCRYPTION
537	if ((d->cfg.bits & MPPE_BITS) != 0) {
538
539		/* Set header bits; need to reset key if we say we did */
540		header |= MPPC_FLAG_ENCRYPTED;
541		if ((header & MPPC_FLAG_FLUSHED) != 0)
542			rc4_init(&d->rc4, d->key, KEYLEN(d->cfg.bits));
543
544		/* Update key if it's time */
545		if ((d->cfg.bits & MPPE_STATELESS) != 0
546		    || (d->cc & MPPE_UPDATE_MASK) == MPPE_UPDATE_FLAG) {
547			  ng_mppc_updatekey(d->cfg.bits,
548			      d->cfg.startkey, d->key, &d->rc4);
549		}
550
551		/* Encrypt packet */
552		rc4_crypt(&d->rc4, outbuf + MPPC_HDRLEN,
553			outbuf + MPPC_HDRLEN, outlen - MPPC_HDRLEN);
554	}
555#endif
556
557	/* Update sequence number */
558	d->cc++;
559
560	/* Install header */
561	*((u_int16_t *)outbuf) = htons(header);
562
563	/* Return packet in an mbuf */
564	*resultp = m_devget((caddr_t)outbuf, outlen, 0, NULL, NULL);
565	FREE(outbuf, M_NETGRAPH_MPPC);
566	return (*resultp == NULL ? ENOBUFS : 0);
567}
568
569/*
570 * Decompress/decrypt packet and put the result in a new mbuf at *resultp.
571 * The original mbuf is not free'd.
572 */
573static int
574ng_mppc_decompress(node_p node, struct mbuf *m, struct mbuf **resultp)
575{
576	const priv_p priv = NG_NODE_PRIVATE(node);
577	struct ng_mppc_dir *const d = &priv->recv;
578	u_int16_t header, cc;
579	u_int numLost;
580	u_char *buf;
581	int len;
582
583	/* Pull off header */
584	if (m->m_pkthdr.len < MPPC_HDRLEN)
585		return (EINVAL);
586	m_copydata(m, 0, MPPC_HDRLEN, (caddr_t)&header);
587	header = ntohs(header);
588	cc = (header & MPPC_CCOUNT_MASK);
589
590	/* Copy payload into a contiguous region of memory */
591	len = m->m_pkthdr.len - MPPC_HDRLEN;
592	MALLOC(buf, u_char *, len, M_NETGRAPH_MPPC, M_NOWAIT);
593	if (buf == NULL)
594		return (ENOMEM);
595	m_copydata(m, MPPC_HDRLEN, len, (caddr_t)buf);
596
597	/* Check for an unexpected jump in the sequence number */
598	numLost = ((cc - d->cc) & MPPC_CCOUNT_MASK);
599
600	/* If flushed bit set, we can always handle packet */
601	if ((header & MPPC_FLAG_FLUSHED) != 0) {
602#ifdef NETGRAPH_MPPC_COMPRESSION
603		if (d->history != NULL)
604			MPPC_InitDecompressionHistory(d->history);
605#endif
606#ifdef NETGRAPH_MPPC_ENCRYPTION
607		if ((d->cfg.bits & MPPE_BITS) != 0) {
608			u_int rekey;
609
610			/* How many times are we going to have to re-key? */
611			rekey = ((d->cfg.bits & MPPE_STATELESS) != 0) ?
612			    numLost : (numLost / (MPPE_UPDATE_MASK + 1));
613			if (rekey > MPPE_MAX_REKEY) {
614				log(LOG_ERR, "%s: too many (%d) packets"
615				    " dropped, disabling node %p!",
616				    __func__, numLost, node);
617				priv->recv.cfg.enable = 0;
618				goto failed;
619			}
620
621			/* Re-key as necessary to catch up to peer */
622			while (d->cc != cc) {
623				if ((d->cfg.bits & MPPE_STATELESS) != 0
624				    || (d->cc & MPPE_UPDATE_MASK)
625				      == MPPE_UPDATE_FLAG) {
626					ng_mppc_updatekey(d->cfg.bits,
627					    d->cfg.startkey, d->key, &d->rc4);
628				}
629				d->cc++;
630			}
631
632			/* Reset key (except in stateless mode, see below) */
633			if ((d->cfg.bits & MPPE_STATELESS) == 0)
634				rc4_init(&d->rc4, d->key, KEYLEN(d->cfg.bits));
635		}
636#endif
637		d->cc = cc;		/* skip over lost seq numbers */
638		numLost = 0;		/* act like no packets were lost */
639	}
640
641	/* Can't decode non-sequential packets without a flushed bit */
642	if (numLost != 0)
643		goto failed;
644
645	/* Decrypt packet */
646	if ((header & MPPC_FLAG_ENCRYPTED) != 0) {
647
648		/* Are we not expecting encryption? */
649		if ((d->cfg.bits & MPPE_BITS) == 0) {
650			log(LOG_ERR, "%s: rec'd unexpectedly %s packet",
651				__func__, "encrypted");
652			goto failed;
653		}
654
655#ifdef NETGRAPH_MPPC_ENCRYPTION
656		/* Update key if it's time (always in stateless mode) */
657		if ((d->cfg.bits & MPPE_STATELESS) != 0
658		    || (d->cc & MPPE_UPDATE_MASK) == MPPE_UPDATE_FLAG) {
659			ng_mppc_updatekey(d->cfg.bits,
660			    d->cfg.startkey, d->key, &d->rc4);
661		}
662
663		/* Decrypt packet */
664		rc4_crypt(&d->rc4, buf, buf, len);
665#endif
666	} else {
667
668		/* Are we expecting encryption? */
669		if ((d->cfg.bits & MPPE_BITS) != 0) {
670			log(LOG_ERR, "%s: rec'd unexpectedly %s packet",
671				__func__, "unencrypted");
672			goto failed;
673		}
674	}
675
676	/* Update coherency count for next time (12 bit arithmetic) */
677	d->cc++;
678
679	/* Check for unexpected compressed packet */
680	if ((header & MPPC_FLAG_COMPRESSED) != 0
681	    && (d->cfg.bits & MPPC_BIT) == 0) {
682		log(LOG_ERR, "%s: rec'd unexpectedly %s packet",
683			__func__, "compressed");
684failed:
685		FREE(buf, M_NETGRAPH_MPPC);
686		return (EINVAL);
687	}
688
689#ifdef NETGRAPH_MPPC_COMPRESSION
690	/* Decompress packet */
691	if ((header & MPPC_FLAG_COMPRESSED) != 0) {
692		int flags = MPPC_MANDATORY_DECOMPRESS_FLAGS;
693		u_char *decompbuf, *source, *dest;
694		u_long sourceCnt, destCnt;
695		int decomplen, rtn;
696
697		/* Allocate a buffer for decompressed data */
698		MALLOC(decompbuf, u_char *, MPPC_DECOMP_BUFSIZE
699		    + MPPC_DECOMP_SAFETY, M_NETGRAPH_MPPC, M_NOWAIT);
700		if (decompbuf == NULL) {
701			FREE(buf, M_NETGRAPH_MPPC);
702			return (ENOMEM);
703		}
704		decomplen = MPPC_DECOMP_BUFSIZE;
705
706		/* Prepare to decompress */
707		source = buf;
708		sourceCnt = len;
709		dest = decompbuf;
710		destCnt = decomplen;
711		if ((header & MPPC_FLAG_RESTART) != 0)
712			flags |= MPPC_RESTART_HISTORY;
713
714		/* Decompress */
715		rtn = MPPC_Decompress(&source, &dest,
716			&sourceCnt, &destCnt, d->history, flags);
717
718		/* Check return value */
719		KASSERT(rtn != MPPC_INVALID, ("%s: invalid", __func__));
720		if ((rtn & MPPC_DEST_EXHAUSTED) != 0
721		    || (rtn & MPPC_DECOMP_OK) != MPPC_DECOMP_OK) {
722			log(LOG_ERR, "%s: decomp returned 0x%x",
723			    __func__, rtn);
724			FREE(decompbuf, M_NETGRAPH_MPPC);
725			goto failed;
726		}
727
728		/* Replace compressed data with decompressed data */
729		FREE(buf, M_NETGRAPH_MPPC);
730		buf = decompbuf;
731		len = decomplen - destCnt;
732	}
733#endif
734
735	/* Return result in an mbuf */
736	*resultp = m_devget((caddr_t)buf, len, 0, NULL, NULL);
737	FREE(buf, M_NETGRAPH_MPPC);
738	return (*resultp == NULL ? ENOBUFS : 0);
739}
740
741/*
742 * The peer has sent us a CCP ResetRequest, so reset our transmit state.
743 */
744static void
745ng_mppc_reset_req(node_p node)
746{
747	const priv_p priv = NG_NODE_PRIVATE(node);
748	struct ng_mppc_dir *const d = &priv->xmit;
749
750#ifdef NETGRAPH_MPPC_COMPRESSION
751	if (d->history != NULL)
752		MPPC_InitCompressionHistory(d->history);
753#endif
754#ifdef NETGRAPH_MPPC_ENCRYPTION
755	if ((d->cfg.bits & MPPE_STATELESS) == 0)
756		rc4_init(&d->rc4, d->key, KEYLEN(d->cfg.bits));
757#endif
758	d->flushed = 1;
759}
760
761/*
762 * Generate a new encryption key
763 */
764static void
765ng_mppc_getkey(const u_char *h, u_char *h2, int len)
766{
767	static const u_char pad1[10] =
768	    { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, };
769	static const u_char pad2[10] =
770	    { 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, 0xF2, };
771	u_char hash[20];
772	SHA1_CTX c;
773	int k;
774
775	bzero(&hash, sizeof(hash));
776	SHA1Init(&c);
777	SHA1Update(&c, h, len);
778	for (k = 0; k < 4; k++)
779		SHA1Update(&c, pad1, sizeof(pad2));
780	SHA1Update(&c, h2, len);
781	for (k = 0; k < 4; k++)
782		SHA1Update(&c, pad2, sizeof(pad2));
783	SHA1Final(hash, &c);
784	bcopy(hash, h2, len);
785}
786
787/*
788 * Update the encryption key
789 */
790static void
791ng_mppc_updatekey(u_int32_t bits,
792	u_char *key0, u_char *key, struct rc4_state *rc4)
793{
794	const int keylen = KEYLEN(bits);
795
796	ng_mppc_getkey(key0, key, keylen);
797	rc4_init(rc4, key, keylen);
798	rc4_crypt(rc4, key, key, keylen);
799	if ((bits & MPPE_40) != 0)
800		bcopy(&ng_mppe_weakenkey, key, 3);
801	else if ((bits & MPPE_56) != 0)
802		bcopy(&ng_mppe_weakenkey, key, 1);
803	rc4_init(rc4, key, keylen);
804}
805
806