linux/generic: add kernel mppc/mppe for 2.6.37. http://yablochkin.net.ru/mppc/ (not enabled by default)

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@24014 3c298f89-4303-0410-b956-a3cf2f4a3e73

3 files changed, 1747 insertions, 2 deletions

diff --git a/package/kernel/modules/netsupport.mk b/package/kernel/modules/netsupport.mk
index 1baba4b5b7..06adfddb6f 100644
--- a/package/kernel/modules/netsupport.mk
+++ b/package/kernel/modules/netsupport.mk
@@ -511,8 +511,8 @@ define KernelPackage/mppe
   KCONFIG:= \
 	CONFIG_PPP_MPPE_MPPC \
 	CONFIG_PPP_MPPE
-  FILES:=$(LINUX_DIR)/drivers/net/ppp_mppe.ko
-  AUTOLOAD:=$(call AutoLoad,31,ppp_mppe)
+  FILES:=$(LINUX_DIR)/drivers/net/ppp_mppe*.ko
+  AUTOLOAD:=$(call AutoLoad,31,ppp_mppe ppp_mppe_mppc)
 endef
 
 define KernelPackage/mppe/description
diff --git a/target/linux/generic/config-2.6.37 b/target/linux/generic/config-2.6.37
index c44f0ff14a..2366e9578f 100644
--- a/target/linux/generic/config-2.6.37
+++ b/target/linux/generic/config-2.6.37
@@ -1820,6 +1820,7 @@ CONFIG_PPC_4K_PAGES=y
 # CONFIG_PPP_DEFLATE is not set
 CONFIG_PPP_FILTER=y
 # CONFIG_PPP_MPPE is not set
+# CONFIG_PPP_MPPE_MPPC is not set
 CONFIG_PPP_MULTILINK=y
 # CONFIG_PPP_SYNC_TTY is not set
 # CONFIG_PPS is not set
diff --git a/target/linux/generic/patches-2.6.37/251-mppe_mppc_2_6_36.patch b/target/linux/generic/patches-2.6.37/251-mppe_mppc_2_6_36.patch
new file mode 100644
index 0000000000..6deca35f1a
--- /dev/null
+++ b/target/linux/generic/patches-2.6.37/251-mppe_mppc_2_6_36.patch
@@ -0,0 +1,1744 @@
+--- a/crypto/api.c
++++ b/crypto/api.c
+@@ -602,5 +602,20 @@ int crypto_has_alg(const char *name, u32
+ }
+ EXPORT_SYMBOL_GPL(crypto_has_alg);
+ 
++int crypto_alg_available(const char *name, u32 flags)
++{
++	int ret = 0;
++	struct crypto_alg *alg = crypto_alg_mod_lookup(name, 0,
++						       CRYPTO_ALG_ASYNC);
++	
++	if (!IS_ERR(alg)) {
++		crypto_mod_put(alg);
++		ret = 1;
++	}
++	
++	return ret;
++}
++EXPORT_SYMBOL_GPL(crypto_alg_available);
++
+ MODULE_DESCRIPTION("Cryptographic core API");
+ MODULE_LICENSE("GPL");
+--- a/drivers/net/Kconfig
++++ b/drivers/net/Kconfig
+@@ -3349,19 +3349,31 @@ config PPP_BSDCOMP
+ 	  module; it is called bsd_comp and will show up in the directory
+ 	  modules once you have said "make modules". If unsure, say N.
+ 
+-config PPP_MPPE
+-       tristate "PPP MPPE compression (encryption) (EXPERIMENTAL)"
+-       depends on PPP && EXPERIMENTAL
+-       select CRYPTO
+-       select CRYPTO_SHA1
+-       select CRYPTO_ARC4
+-       select CRYPTO_ECB
+-       ---help---
+-         Support for the MPPE Encryption protocol, as employed by the
+-	 Microsoft Point-to-Point Tunneling Protocol.
++config PPP_MPPE_MPPC
++	tristate "Microsoft PPP compression/encryption (MPPC/MPPE)"
++	depends on PPP
++	select CRYPTO_SHA1
++	select CRYPTO_ARC4
++	---help---
++	  Support for the Microsoft Point-To-Point Compression (RFC2118) and 
++	  Microsoft Point-To-Point Encryption (RFC3078). These protocols are
++	  supported by Microsoft Windows and wide range of "hardware" access
++	  servers. MPPE is common protocol in Virtual Private Networks. According
++	  to RFC3078, MPPE supports 40, 56 and 128-bit key lengths. Depending on
++	  PPP daemon configuration on both ends of the link, following scenarios
++	  are possible:
++		- only compression (MPPC) is used,
++		- only encryption (MPPE) is used,
++		- compression and encryption (MPPC+MPPE) are used.
+ 
+-	 See http://pptpclient.sourceforge.net/ for information on
+-	 configuring PPTP clients and servers to utilize this method.
++	  Please note that Hi/Fn (http://www.hifn.com) holds patent on MPPC so
++	  you should check if this patent is valid in your country in order to
++	  avoid legal problems.
++
++	  For more information please visit http://mppe-mppc.alphacron.de
++
++	  To compile this driver as a module, choose M here. The module will
++	  be called ppp_mppe_mppc.ko.
+ 
+ config PPPOE
+ 	tristate "PPP over Ethernet (EXPERIMENTAL)"
+--- a/drivers/net/Makefile
++++ b/drivers/net/Makefile
+@@ -162,7 +162,7 @@ obj-$(CONFIG_PPP_ASYNC) += ppp_async.o
+ obj-$(CONFIG_PPP_SYNC_TTY) += ppp_synctty.o
+ obj-$(CONFIG_PPP_DEFLATE) += ppp_deflate.o
+ obj-$(CONFIG_PPP_BSDCOMP) += bsd_comp.o
+-obj-$(CONFIG_PPP_MPPE) += ppp_mppe.o
++obj-$(CONFIG_PPP_MPPE_MPPC) += ppp_mppe_mppc.o
+ obj-$(CONFIG_PPPOE) += pppox.o pppoe.o
+ obj-$(CONFIG_PPPOL2TP) += pppox.o
+ obj-$(CONFIG_PPTP) += pppox.o pptp.o
+--- a/drivers/net/ppp_generic.c
++++ b/drivers/net/ppp_generic.c
+@@ -41,6 +41,7 @@
+ #include <linux/ip.h>
+ #include <linux/tcp.h>
+ #include <linux/spinlock.h>
++#include <linux/smp_lock.h>
+ #include <linux/rwsem.h>
+ #include <linux/stddef.h>
+ #include <linux/device.h>
+@@ -87,10 +88,11 @@ struct ppp_file {
+ 	int		dead;		/* unit/channel has been shut down */
+ };
+ 
+-#define PF_TO_X(pf, X)		container_of(pf, X, file)
++#define PF_TO_X(pf, X)		((X *)((char *)(pf) - offsetof(X, file)))
+ 
+ #define PF_TO_PPP(pf)		PF_TO_X(pf, struct ppp)
+ #define PF_TO_CHANNEL(pf)	PF_TO_X(pf, struct channel)
++#define ROUNDUP(n, x)		(((n) + (x) - 1) / (x))
+ 
+ /*
+  * Data structure describing one ppp unit.
+@@ -106,6 +108,7 @@ struct ppp {
+ 	spinlock_t	rlock;		/* lock for receive side 58 */
+ 	spinlock_t	wlock;		/* lock for transmit side 5c */
+ 	int		mru;		/* max receive unit 60 */
++	int		mru_alloc;	/* MAX(1500,MRU) for dev_alloc_skb() */
+ 	unsigned int	flags;		/* control bits 64 */
+ 	unsigned int	xstate;		/* transmit state bits 68 */
+ 	unsigned int	rstate;		/* receive state bits 6c */
+@@ -139,14 +142,13 @@ struct ppp {
+ 
+ /*
+  * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC,
+- * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
+- * SC_MUST_COMP
++ * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP.
+  * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
+  * Bits in xstate: SC_COMP_RUN
+  */
+ #define SC_FLAG_BITS	(SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \
+ 			 |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \
+-			 |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
++		     |SC_COMP_TCP|SC_REJ_COMP_TCP)
+ 
+ /*
+  * Private data structure for each channel.
+@@ -639,7 +641,9 @@ static long ppp_ioctl(struct file *file,
+ 	case PPPIOCSMRU:
+ 		if (get_user(val, p))
+ 			break;
+-		ppp->mru = val;
++		ppp->mru_alloc = ppp->mru = val;
++	if (ppp->mru_alloc < PPP_MRU)
++	    ppp->mru_alloc = PPP_MRU;	/* increase for broken peers */
+ 		err = 0;
+ 		break;
+ 
+@@ -1066,56 +1070,6 @@ ppp_xmit_process(struct ppp *ppp)
+ 	ppp_xmit_unlock(ppp);
+ }
+ 
+-static inline struct sk_buff *
+-pad_compress_skb(struct ppp *ppp, struct sk_buff *skb)
+-{
+-	struct sk_buff *new_skb;
+-	int len;
+-	int new_skb_size = ppp->dev->mtu +
+-		ppp->xcomp->comp_extra + ppp->dev->hard_header_len;
+-	int compressor_skb_size = ppp->dev->mtu +
+-		ppp->xcomp->comp_extra + PPP_HDRLEN;
+-	new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
+-	if (!new_skb) {
+-		if (net_ratelimit())
+-			printk(KERN_ERR "PPP: no memory (comp pkt)\n");
+-		return NULL;
+-	}
+-	if (ppp->dev->hard_header_len > PPP_HDRLEN)
+-		skb_reserve(new_skb,
+-			    ppp->dev->hard_header_len - PPP_HDRLEN);
+-
+-	/* compressor still expects A/C bytes in hdr */
+-	len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
+-				   new_skb->data, skb->len + 2,
+-				   compressor_skb_size);
+-	if (len > 0 && (ppp->flags & SC_CCP_UP)) {
+-		kfree_skb(skb);
+-		skb = new_skb;
+-		skb_put(skb, len);
+-		skb_pull(skb, 2);	/* pull off A/C bytes */
+-	} else if (len == 0) {
+-		/* didn't compress, or CCP not up yet */
+-		kfree_skb(new_skb);
+-		new_skb = skb;
+-	} else {
+-		/*
+-		 * (len < 0)
+-		 * MPPE requires that we do not send unencrypted
+-		 * frames.  The compressor will return -1 if we
+-		 * should drop the frame.  We cannot simply test
+-		 * the compress_proto because MPPE and MPPC share
+-		 * the same number.
+-		 */
+-		if (net_ratelimit())
+-			printk(KERN_ERR "ppp: compressor dropped pkt\n");
+-		kfree_skb(skb);
+-		kfree_skb(new_skb);
+-		new_skb = NULL;
+-	}
+-	return new_skb;
+-}
+-
+ /*
+  * Compress and send a frame.
+  * The caller should have locked the xmit path,
+@@ -1196,20 +1150,62 @@ ppp_send_frame(struct ppp *ppp, struct s
+ 	case PPP_CCP:
+ 		/* peek at outbound CCP frames */
+ 		ppp_ccp_peek(ppp, skb, 0);
++		if (CCP_CODE(skb->data+2) == CCP_RESETACK
++			&& (ppp->xcomp->compress_proto == CI_MPPE
++				|| ppp->xcomp->compress_proto == CI_LZS)) {
++			--ppp->dev->stats.tx_packets;
++			ppp->dev->stats.tx_bytes -= skb->len - 2;
++			kfree_skb(skb);
++			return;
++		}
+ 		break;
+ 	}
+ 
+ 	/* try to do packet compression */
+ 	if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state &&
+ 	    proto != PPP_LCP && proto != PPP_CCP) {
+-		if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
+-			if (net_ratelimit())
+-				printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
++	    	int comp_ovhd = 0;
++		/* 
++		 * because of possible data expansion when MPPC or LZS
++		 * is used, allocate compressor's buffer 12.5% bigger
++		 * than MTU
++		 */
++		if (ppp->xcomp->compress_proto == CI_MPPE)
++			comp_ovhd = ((ppp->dev->mtu * 9) / 8) + 1 + MPPE_OVHD;
++		else if (ppp->xcomp->compress_proto == CI_LZS)
++			comp_ovhd = ((ppp->dev->mtu * 9) / 8) + 1 + LZS_OVHD;
++		new_skb = alloc_skb(ppp->dev->mtu + ppp->dev->hard_header_len
++				+ comp_ovhd, GFP_ATOMIC);
++		if (new_skb == 0) {
++			 printk(KERN_ERR "PPP: no memory (comp pkt)\n");
+ 			goto drop;
+ 		}
+-		skb = pad_compress_skb(ppp, skb);
+-		if (!skb)
++		if (ppp->dev->hard_header_len > PPP_HDRLEN)
++			skb_reserve(new_skb,
++				ppp->dev->hard_header_len - PPP_HDRLEN);
++
++		/* compressor still expects A/C bytes in hdr */
++		len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2,
++					new_skb->data, skb->len + 2,
++					ppp->dev->mtu + PPP_HDRLEN);
++		if (len > 0 && (ppp->flags & SC_CCP_UP)) {
++			kfree_skb(skb);
++			skb = new_skb;
++			skb_put(skb, len);
++			skb_pull(skb, 2);       /* pull off A/C bytes */
++		} else if (len == 0) {
++			/*
++			 * (len < 0)
++			 * MPPE requires that we do not send unencrypted
++			 * frames.  The compressor will return -1 if we
++			 * should drop the frame.  We cannot simply test
++			 * the compress_proto because MPPE and MPPC share
++			 * the same number.
++			 */
++			printk(KERN_ERR "ppp: compressor dropped pkt\n");
++			kfree_skb(new_skb);
+ 			goto drop;
++		}
+ 	}
+ 
+ 	/*
+@@ -1670,9 +1666,6 @@ ppp_receive_nonmp_frame(struct ppp *ppp,
+ 	    (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
+ 		skb = ppp_decompress_frame(ppp, skb);
+ 
+-	if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
+-		goto err;
+-
+ 	proto = PPP_PROTO(skb);
+ 	switch (proto) {
+ 	case PPP_VJC_COMP:
+@@ -1852,7 +1845,14 @@ ppp_decompress_frame(struct ppp *ppp, st
+ 	return skb;
+ 
+  err:
+-	ppp->rstate |= SC_DC_ERROR;
++	if (ppp->rcomp->compress_proto != CI_MPPE
++	    && ppp->rcomp->compress_proto != CI_LZS) {
++	    /*
++	     * If decompression protocol isn't MPPE/MPPC or LZS, we set
++	     * SC_DC_ERROR flag and wait for CCP_RESETACK
++	     */
++	    ppp->rstate |= SC_DC_ERROR;
++	}
+ 	ppp_receive_error(ppp);
+ 	return skb;
+ }
+@@ -2566,6 +2566,7 @@ ppp_create_interface(struct net *net, in
+ 	ppp = netdev_priv(dev);
+ 	ppp->dev = dev;
+ 	ppp->mru = PPP_MRU;
++	ppp->mru_alloc = PPP_MRU;
+ 	init_ppp_file(&ppp->file, INTERFACE);
+ 	ppp->file.hdrlen = PPP_HDRLEN - 2;	/* don't count proto bytes */
+ 	for (i = 0; i < NUM_NP; ++i)
+--- /dev/null
++++ b/drivers/net/ppp_mppe_mppc.c
+@@ -0,0 +1,1308 @@
++/*
++ * ppp_mppe_mppc.c - MPPC/MPPE "compressor/decompressor" module.
++ *
++ * Copyright (c) 1994 Árpád Magosányi <mag@bunuel.tii.matav.hu>
++ * Copyright (c) 1999 Tim Hockin, Cobalt Networks Inc. <thockin@cobaltnet.com>
++ * Copyright (c) 2002-2004 Jan Dubiec <jdx@slackware.pl>
++ * 
++ * Permission to use, copy, modify, and distribute this software and its
++ * documentation is hereby granted, provided that the above copyright
++ * notice appears in all copies. This software is provided without any
++ * warranty, express or implied.
++ *
++ * The code is based on MPPE kernel module written by Árpád Magosányi and
++ * Tim Hockin which can be found on http://planetmirror.com/pub/mppe/.
++ * I have added MPPC and 56 bit session keys support in MPPE.
++ *
++ * WARNING! Although this is open source code, its usage in some countries
++ * (in particular in the USA) may violate Stac Inc. patent for MPPC.
++ *
++ *  ==FILEVERSION 20041123==
++ *
++ */
++
++#include <linux/init.h>
++#include <linux/module.h>
++#include <linux/mm.h>
++#include <linux/slab.h>
++#include <asm/scatterlist.h>
++#include <linux/vmalloc.h>
++#include <linux/crypto.h>
++
++#include <linux/ppp_defs.h>
++#include <linux/ppp-comp.h>
++
++/*
++ * State for a mppc/mppe "(de)compressor".
++ */
++struct ppp_mppe_state {
++    struct crypto_tfm *arc4_tfm;
++    struct crypto_hash *sha1_tfm;
++    u8		*sha1_digest;
++    u8		master_key[MPPE_MAX_KEY_LEN];
++    u8		session_key[MPPE_MAX_KEY_LEN];
++    u8		mppc;		/* do we use compression (MPPC)? */
++    u8		mppe;		/* do we use encryption (MPPE)? */
++    u8		keylen;		/* key length in bytes */
++    u8		bitkeylen;	/* key length in bits */
++    u16		ccount;		/* coherency counter */
++    u16		bits;		/* MPPC/MPPE control bits */
++    u8		stateless;	/* do we use stateless mode? */
++    u8		nextflushed;	/* set A bit in the next outgoing packet;
++				   used only by compressor*/
++    u8		flushexpected;	/* drop packets until A bit is received;
++				   used only by decompressor*/
++    u8		*hist;		/* MPPC history */
++    u16		*hash;		/* Hash table; used only by compressor */
++    u16		histptr;	/* history "cursor" */
++    int		unit;
++    int		debug;
++    int		mru;
++    struct compstat stats;
++};
++
++#define MPPE_HIST_LEN		8192	/* MPPC history size */
++#define MPPE_MAX_CCOUNT		0x0FFF	/* max. coherency counter value */
++
++#define MPPE_BIT_FLUSHED	0x80	/* bit A */
++#define MPPE_BIT_RESET		0x40	/* bit B */
++#define MPPE_BIT_COMP		0x20	/* bit C */
++#define MPPE_BIT_ENCRYPTED	0x10	/* bit D */
++
++#define MPPE_SALT0		0xD1	/* values used in MPPE key derivation */
++#define MPPE_SALT1		0x26	/* according to RFC3079 */
++#define MPPE_SALT2		0x9E
++
++#define MPPE_CCOUNT(x)		((((x)[4] & 0x0f) << 8) + (x)[5])
++#define MPPE_BITS(x)		((x)[4] & 0xf0)
++#define MPPE_CTRLHI(x)		((((x)->ccount & 0xf00)>>8)|((x)->bits))
++#define MPPE_CTRLLO(x)		((x)->ccount & 0xff)
++
++/*
++ * Kernel Crypto API needs its arguments to be in kmalloc'd memory, not in the
++ * module static data area. That means sha_pad needs to be kmalloc'd. It is done
++ * in mppe_module_init(). This has been pointed out on 30th July 2004 by Oleg
++ * Makarenko on pptpclient-devel mailing list.
++ */
++#define SHA1_PAD_SIZE		40
++struct sha_pad {
++    unsigned char sha_pad1[SHA1_PAD_SIZE];
++    unsigned char sha_pad2[SHA1_PAD_SIZE];
++};
++static struct sha_pad *sha_pad;
++
++static unsigned int
++setup_sg(struct scatterlist *sg, const void  *address, unsigned int length)
++{
++    sg[0].page_link = virt_to_page(address);
++    sg[0].offset = offset_in_page(address);
++    sg[0].length = length;
++    return length;
++}
++
++static inline void
++arc4_setkey(struct ppp_mppe_state *state, const unsigned char *key,
++	    const unsigned int keylen)
++{
++    crypto_cipher_setkey(state->arc4_tfm, key, keylen);
++}
++
++static inline void
++arc4_encrypt(struct ppp_mppe_state *state, const unsigned char *in,
++	     const unsigned int len, unsigned char *out)
++{
++    int i;
++    for (i = 0; i < len; i++)
++    {
++       crypto_cipher_encrypt_one(state->arc4_tfm, out+i, in+i);
++    }
++}
++
++
++#define arc4_decrypt arc4_encrypt
++
++/*
++ * Key Derivation, from RFC 3078, RFC 3079.
++ * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
++ */
++static void
++get_new_key_from_sha(struct ppp_mppe_state *state, unsigned char *interim_key)
++{
++	struct hash_desc desc;
++	struct scatterlist sg[4];
++	unsigned int nbytes;
++
++
++	nbytes = setup_sg(&sg[0], state->master_key, state->keylen);
++	nbytes += setup_sg(&sg[1], sha_pad->sha_pad1,
++			   sizeof(sha_pad->sha_pad1));
++	nbytes += setup_sg(&sg[2], state->session_key, state->keylen);
++	nbytes += setup_sg(&sg[3], sha_pad->sha_pad2,
++			   sizeof(sha_pad->sha_pad2));
++
++	desc.tfm = state->sha1_tfm;
++	desc.flags = 0;
++
++	crypto_hash_digest(&desc, sg, nbytes, state->sha1_digest);
++    memcpy(interim_key, state->sha1_digest, state->keylen);
++}
++
++static void
++mppe_change_key(struct ppp_mppe_state *state, int initialize)
++{
++    unsigned char interim_key[MPPE_MAX_KEY_LEN];
++
++    get_new_key_from_sha(state, interim_key);
++    if (initialize) {
++	memcpy(state->session_key, interim_key, state->keylen);
++    } else {
++	arc4_setkey(state, interim_key, state->keylen);
++	arc4_encrypt(state, interim_key, state->keylen, state->session_key);
++    }
++    if (state->keylen == 8) {
++	if (state->bitkeylen == 40) {
++	    state->session_key[0] = MPPE_SALT0;
++	    state->session_key[1] = MPPE_SALT1;
++	    state->session_key[2] = MPPE_SALT2;
++	} else {
++	    state->session_key[0] = MPPE_SALT0;
++	}
++    }
++    arc4_setkey(state, state->session_key, state->keylen);
++}
++
++/* increase 12-bit coherency counter */
++static inline void
++mppe_increase_ccount(struct ppp_mppe_state *state)
++{
++    state->ccount = (state->ccount + 1) & MPPE_MAX_CCOUNT;
++    if (state->mppe) {
++	if (state->stateless) {
++	    mppe_change_key(state, 0);
++	    state->nextflushed = 1;
++	} else {
++	    if ((state->ccount & 0xff) == 0xff) {
++		mppe_change_key(state, 0);
++	    }
++	}
++    }
++}
++
++/* allocate space for a MPPE/MPPC (de)compressor.  */
++/*   comp != 0 -> init compressor */
++/*   comp = 0 -> init decompressor */
++static void *
++mppe_alloc(unsigned char *options, int opt_len, int comp)
++{
++    struct ppp_mppe_state *state;
++    unsigned int digestsize;
++    u8* fname;
++
++    fname = comp ? "mppe_comp_alloc" : "mppe_decomp_alloc";
++
++    /*  
++     * Hack warning - additionally to the standard MPPC/MPPE configuration
++     * options, pppd passes to the (de)copressor 8 or 16 byte session key.
++     * Therefore options[1] contains MPPC/MPPE configuration option length
++     * (CILEN_MPPE = 6), but the real options length, depending on the key
++     * length, is 6+8 or 6+16.
++     */
++    if (opt_len < CILEN_MPPE) {
++	printk(KERN_WARNING "%s: wrong options length: %u\n", fname, opt_len);
++	return NULL;
++    }
++
++    if (options[0] != CI_MPPE || options[1] != CILEN_MPPE ||
++	(options[2] & ~MPPE_STATELESS) != 0 ||
++	options[3] != 0 || options[4] != 0 ||
++	(options[5] & ~(MPPE_128BIT|MPPE_56BIT|MPPE_40BIT|MPPE_MPPC)) != 0 ||
++	(options[5] & (MPPE_128BIT|MPPE_56BIT|MPPE_40BIT|MPPE_MPPC)) == 0) {
++	printk(KERN_WARNING "%s: options rejected: o[0]=%02x, o[1]=%02x, "
++	       "o[2]=%02x, o[3]=%02x, o[4]=%02x, o[5]=%02x\n", fname, options[0],
++	       options[1], options[2], options[3], options[4], options[5]);
++	return NULL;
++    }
++
++    state = (struct ppp_mppe_state *)kmalloc(sizeof(*state), GFP_KERNEL);
++    if (state == NULL) {
++	printk(KERN_ERR "%s: cannot allocate space for %scompressor\n", fname,
++	       comp ? "" : "de");
++	return NULL;
++    }
++    memset(state, 0, sizeof(struct ppp_mppe_state));
++
++    state->mppc = options[5] & MPPE_MPPC;	/* Do we use MPPC? */
++    state->mppe = options[5] & (MPPE_128BIT | MPPE_56BIT |
++	MPPE_40BIT);				/* Do we use MPPE? */
++
++    if (state->mppc) {
++	/* allocate MPPC history */
++	state->hist = (u8*)vmalloc(2*MPPE_HIST_LEN*sizeof(u8));
++	if (state->hist == NULL) {
++	    kfree(state);
++	    printk(KERN_ERR "%s: cannot allocate space for MPPC history\n",
++		   fname);
++	    return NULL;
++	}
++
++	/* allocate hashtable for MPPC compressor */
++	if (comp) {
++	    state->hash = (u16*)vmalloc(MPPE_HIST_LEN*sizeof(u16));
++	    if (state->hash == NULL) {
++		vfree(state->hist);
++		kfree(state);
++		printk(KERN_ERR "%s: cannot allocate space for MPPC history\n",
++		       fname);
++		return NULL;
++	    }
++	}
++    }
++
++    if (state->mppe) { /* specific for MPPE */
++	/* Load ARC4 algorithm */
++	state->arc4_tfm = crypto_alloc_base("arc4", 0, 0);
++	if (state->arc4_tfm == NULL) {
++	    if (state->mppc) {
++		vfree(state->hash);
++		if (comp)
++		    vfree(state->hist);
++	    }
++	    kfree(state);
++	    printk(KERN_ERR "%s: cannot load ARC4 module\n", fname);
++	    return NULL;
++	}
++
++	/* Load SHA1 algorithm */
++	state->sha1_tfm = crypto_alloc_hash("sha1", 0, CRYPTO_ALG_ASYNC);
++	if (state->sha1_tfm == NULL) {
++	    crypto_free_tfm(state->arc4_tfm);
++	    if (state->mppc) {
++		vfree(state->hash);
++		if (comp)
++		    vfree(state->hist);
++	    }
++	    kfree(state);
++	    printk(KERN_ERR "%s: cannot load SHA1 module\n", fname);
++	    return NULL;
++	}
++
++	digestsize = crypto_hash_digestsize(state->sha1_tfm);
++	if (digestsize < MPPE_MAX_KEY_LEN) {
++	    crypto_free_hash(state->sha1_tfm);
++	    crypto_free_tfm(state->arc4_tfm);
++	    if (state->mppc) {
++		vfree(state->hash);
++		if (comp)
++		    vfree(state->hist);
++	    }
++	    kfree(state);
++	    printk(KERN_ERR "%s: CryptoAPI SHA1 digest size too small\n", fname);
++	}
++
++	state->sha1_digest = kmalloc(digestsize, GFP_KERNEL);
++	if (!state->sha1_digest) {
++	    crypto_free_hash(state->sha1_tfm);
++	    crypto_free_tfm(state->arc4_tfm);
++	    if (state->mppc) {
++		vfree(state->hash);
++		if (comp)
++		    vfree(state->hist);
++	    }
++	    kfree(state);
++	    printk(KERN_ERR "%s: cannot allocate space for SHA1 digest\n", fname);
++	}
++
++	memcpy(state->master_key, options+CILEN_MPPE, MPPE_MAX_KEY_LEN);
++	memcpy(state->session_key, state->master_key, MPPE_MAX_KEY_LEN);
++	/* initial key generation is done in mppe_init() */
++    }
++
++    return (void *) state;
++}
++
++static void *
++mppe_comp_alloc(unsigned char *options, int opt_len)
++{
++    return mppe_alloc(options, opt_len, 1);
++}
++
++static void *
++mppe_decomp_alloc(unsigned char *options, int opt_len)
++{
++    return mppe_alloc(options, opt_len, 0);
++}
++
++/* cleanup the (de)compressor */
++static void
++mppe_comp_free(void *arg)
++{
++    struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
++
++    if (state != NULL) {
++	if (state->mppe) {
++	    if (state->sha1_digest != NULL)
++		kfree(state->sha1_digest);
++	    if (state->sha1_tfm != NULL)
++		crypto_free_hash(state->sha1_tfm);
++	    if (state->arc4_tfm != NULL)
++		crypto_free_tfm(state->arc4_tfm);
++	}
++	if (state->hist != NULL)
++	    vfree(state->hist);
++	if (state->hash != NULL)
++	    vfree(state->hash);
++	kfree(state);
++    }
++}
++
++/* init MPPC/MPPE (de)compresor */
++/*   comp != 0 -> init compressor */
++/*   comp = 0 -> init decompressor */
++static int
++mppe_init(void *arg, unsigned char *options, int opt_len, int unit,
++	  int hdrlen, int mru, int debug, int comp)
++{
++    struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
++    u8* fname;
++
++    fname = comp ? "mppe_comp_init" : "mppe_decomp_init";
++
++    if (opt_len < CILEN_MPPE) {
++	if (debug)
++	    printk(KERN_WARNING "%s: wrong options length: %u\n",
++		   fname, opt_len);
++	return 0;
++    }
++
++    if (options[0] != CI_MPPE || options[1] != CILEN_MPPE ||
++	(options[2] & ~MPPE_STATELESS) != 0 ||
++	options[3] != 0 || options[4] != 0 ||
++	(options[5] & ~(MPPE_56BIT|MPPE_128BIT|MPPE_40BIT|MPPE_MPPC)) != 0 ||
++	(options[5] & (MPPE_56BIT|MPPE_128BIT|MPPE_40BIT|MPPE_MPPC)) == 0) {
++	if (debug)
++	    printk(KERN_WARNING "%s: options rejected: o[0]=%02x, o[1]=%02x, "
++		   "o[2]=%02x, o[3]=%02x, o[4]=%02x, o[5]=%02x\n", fname,
++		   options[0], options[1], options[2], options[3], options[4],
++		   options[5]);
++	return 0;
++    }
++
++    if ((options[5] & ~MPPE_MPPC) != MPPE_128BIT &&
++	(options[5] & ~MPPE_MPPC) != MPPE_56BIT &&
++	(options[5] & ~MPPE_MPPC) != MPPE_40BIT &&
++	(options[5] & MPPE_MPPC) != MPPE_MPPC) {
++	if (debug)
++	    printk(KERN_WARNING "%s: don't know what to do: o[5]=%02x\n",
++		   fname, options[5]);
++	return 0;
++    }
++
++    state->mppc = options[5] & MPPE_MPPC;	/* Do we use MPPC? */
++    state->mppe = options[5] & (MPPE_128BIT | MPPE_56BIT |
++	MPPE_40BIT);				/* Do we use MPPE? */
++    state->stateless = options[2] & MPPE_STATELESS; /* Do we use stateless mode? */
++
++    switch (state->mppe) {
++    case MPPE_40BIT:     /* 40 bit key */
++	state->keylen = 8;
++	state->bitkeylen = 40;
++	break;
++    case MPPE_56BIT:     /* 56 bit key */
++	state->keylen = 8;
++	state->bitkeylen = 56;
++	break;
++    case MPPE_128BIT:    /* 128 bit key */
++	state->keylen = 16;
++	state->bitkeylen = 128;
++	break;
++    default:
++	state->keylen = 0;
++	state->bitkeylen = 0;
++    }
++
++    state->ccount = MPPE_MAX_CCOUNT;
++    state->bits = 0;
++    state->unit  = unit;
++    state->debug = debug;
++    state->histptr = MPPE_HIST_LEN;
++    if (state->mppc) {	/* reset history if MPPC was negotiated */
++	memset(state->hist, 0, 2*MPPE_HIST_LEN*sizeof(u8));
++    }
++
++    if (state->mppe) { /* generate initial session keys */
++	mppe_change_key(state, 1);
++    }
++
++    if (comp) { /* specific for compressor */
++	state->nextflushed = 1;
++    } else { /* specific for decompressor */
++	state->mru = mru;
++	state->flushexpected = 1;
++    }
++
++    return 1;
++}
++
++static int
++mppe_comp_init(void *arg, unsigned char *options, int opt_len, int unit,
++	       int hdrlen, int debug)
++{
++    return mppe_init(arg, options, opt_len, unit, hdrlen, 0, debug, 1);
++}
++
++
++static int
++mppe_decomp_init(void *arg, unsigned char *options, int opt_len, int unit,
++		 int hdrlen, int mru, int debug)
++{
++    return mppe_init(arg, options, opt_len, unit, hdrlen, mru, debug, 0);
++}
++
++static void
++mppe_comp_reset(void *arg)
++{
++    struct ppp_mppe_state *state = (struct ppp_mppe_state *)arg;
++
++    if (state->debug)
++	printk(KERN_DEBUG "%s%d: resetting MPPC/MPPE compressor\n",
++	       __FUNCTION__, state->unit);
++
++    state->nextflushed = 1;
++    if (state->mppe)
++	arc4_setkey(state, state->session_key, state->keylen);
++}
++
++static void
++mppe_decomp_reset(void *arg)
++{
++    /* When MPPC/MPPE is in use, we shouldn't receive any CCP Reset-Ack.
++       But when we receive such a packet, we just ignore it. */
++    return;
++}
++
++static void
++mppe_stats(void *arg, struct compstat *stats)
++{
++    struct ppp_mppe_state *state = (struct ppp_mppe_state *)arg;
++
++    *stats = state->stats;
++}
++
++/***************************/
++/**** Compression stuff ****/
++/***************************/
++/* inserts 1 to 8 bits into the output buffer */
++static inline void putbits8(u8 *buf, u32 val, const u32 n, u32 *i, u32 *l)
++{
++    buf += *i;
++    if (*l >= n) {
++	*l = (*l) - n;
++	val <<= *l;
++	*buf = *buf | (val & 0xff);
++	if (*l == 0) {
++	    *l = 8;
++	    (*i)++;
++	    *(++buf) = 0;
++	}
++    } else {
++	(*i)++;
++	*l = 8 - n + (*l);
++	val <<= *l;
++	*buf = *buf | ((val >> 8) & 0xff);
++	*(++buf) = val & 0xff;
++    }
++}
++
++/* inserts 9 to 16 bits into the output buffer */
++static inline void putbits16(u8 *buf, u32 val, const u32 n, u32 *i, u32 *l)
++{
++    buf += *i;
++    if (*l >= n - 8) {
++	(*i)++;
++	*l = 8 - n + (*l);
++	val <<= *l;
++	*buf = *buf | ((val >> 8) & 0xff);
++	*(++buf) = val & 0xff;
++	if (*l == 0) {
++	    *l = 8;
++	    (*i)++;
++	    *(++buf) = 0;
++	}
++    } else {
++	(*i)++; (*i)++;
++	*l = 16 - n + (*l);
++	val <<= *l;
++	*buf = *buf | ((val >> 16) & 0xff);
++	*(++buf) = (val >> 8) & 0xff;
++	*(++buf) = val & 0xff;
++    }
++}
++
++/* inserts 17 to 24 bits into the output buffer */
++static inline void putbits24(u8 *buf, u32 val, const u32 n, u32 *i, u32 *l)
++{
++    buf += *i;
++    if (*l >= n - 16) {
++	(*i)++; (*i)++;
++	*l = 16 - n + (*l);
++	val <<= *l;
++	*buf = *buf | ((val >> 16) & 0xff);
++	*(++buf) = (val >> 8) & 0xff;
++	*(++buf) = val & 0xff;
++	if (*l == 0) {
++	    *l = 8;
++	    (*i)++;
++	    *(++buf) = 0;
++	}
++    } else {
++	(*i)++; (*i)++; (*i)++;
++	*l = 24 - n + (*l);
++	val <<= *l;
++	*buf = *buf | ((val >> 24) & 0xff);
++	*(++buf) = (val >> 16) & 0xff;
++	*(++buf) = (val >> 8) & 0xff;
++	*(++buf) = val & 0xff;
++    }
++}
++
++static int
++mppc_compress(struct ppp_mppe_state *state, unsigned char *ibuf,
++	      unsigned char *obuf, int isize, int osize)
++{
++    u32 olen, off, len, idx, i, l;
++    u8 *hist, *sbuf, *p, *q, *r, *s;
++
++    /*  
++	At this point, to avoid possible buffer overflow caused by packet
++	expansion during/after compression,  we should make sure that
++	osize >= (((isize*9)/8)+1)+2, but we don't do that because in
++	ppp_generic.c we simply allocate bigger obuf.
++
++	Maximum MPPC packet expansion is 12.5%. This is the worst case when
++	all octets in the input buffer are >= 0x80 and we cannot find any
++	repeated tokens. Additionally we have to reserve 2 bytes for MPPE/MPPC
++	status bits and coherency counter.
++    */
++
++    hist = state->hist + MPPE_HIST_LEN;
++    /* check if there is enough room at the end of the history */
++    if (state->histptr + isize >= 2*MPPE_HIST_LEN) {
++	state->bits |= MPPE_BIT_RESET;
++	state->histptr = MPPE_HIST_LEN;
++	memcpy(state->hist, hist, MPPE_HIST_LEN);
++    }
++    /* add packet to the history; isize must be <= MPPE_HIST_LEN */
++    sbuf = state->hist + state->histptr;
++    memcpy(sbuf, ibuf, isize);
++    state->histptr += isize;
++
++    /* compress data */
++    r = sbuf + isize;
++    *obuf = olen = i = 0;
++    l = 8;
++    while (i < isize - 2) {
++	s = q = sbuf + i;
++	idx = ((40543*((((s[0]<<4)^s[1])<<4)^s[2]))>>4) & 0x1fff;
++	p = hist + state->hash[idx];
++	state->hash[idx] = (u16) (s - hist);
++	off = s - p;
++	if (off > MPPE_HIST_LEN - 1 || off < 1 || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++) {
++	    /* no match found; encode literal byte */
++	    if (ibuf[i] < 0x80) {		/* literal byte < 0x80 */
++		putbits8(obuf, (u32) ibuf[i], 8, &olen, &l);
++	    } else {				/* literal byte >= 0x80 */
++		putbits16(obuf, (u32) (0x100|(ibuf[i]&0x7f)), 9, &olen, &l);
++	    }
++	    ++i;
++	    continue;
++	}
++	if (r - q >= 64) {
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++ || *p++ != *s++ || *p++ != *s++ || *p++ != *s++ ||
++	    *p++ != *s++;
++	    if (s - q == 64) {
++		p--; s--;
++		while((*p++ == *s++) && (s < r) && (p < q));
++	    }
++	} else {
++	    while((*p++ == *s++) && (s < r) && (p < q));
++	}
++	len = s - q - 1;
++	i += len;
++
++	/* at least 3 character match found; code data */
++	/* encode offset */
++	if (off < 64) {			/* 10-bit offset; 0 <= offset < 64 */
++	    putbits16(obuf, 0x3c0|off, 10, &olen, &l);
++	} else if (off < 320) {		/* 12-bit offset; 64 <= offset < 320 */
++	    putbits16(obuf, 0xe00|(off-64), 12, &olen, &l);
++	} else if (off < 8192) {	/* 16-bit offset; 320 <= offset < 8192 */
++	    putbits16(obuf, 0xc000|(off-320), 16, &olen, &l);
++	} else {
++	    /* This shouldn't happen; we return 0 what means "packet expands",
++	    and we send packet uncompressed. */
++	    if (state->debug)
++		printk(KERN_DEBUG "%s%d: wrong offset value: %d\n",
++		       __FUNCTION__, state->unit, off);
++	    return 0;
++	}
++	/* encode length of match */
++	if (len < 4) {			/* length = 3 */
++	    putbits8(obuf, 0, 1, &olen, &l);
++	} else if (len < 8) {		/* 4 <= length < 8 */
++	    putbits8(obuf, 0x08|(len&0x03), 4, &olen, &l);
++	} else if (len < 16) {		/* 8 <= length < 16 */
++	    putbits8(obuf, 0x30|(len&0x07), 6, &olen, &l);
++	} else if (len < 32) {		/* 16 <= length < 32 */
++	    putbits8(obuf, 0xe0|(len&0x0f), 8, &olen, &l);
++	} else if (len < 64) {		/* 32 <= length < 64 */
++	    putbits16(obuf, 0x3c0|(len&0x1f), 10, &olen, &l);
++	} else if (len < 128) {		/* 64 <= length < 128 */
++	    putbits16(obuf, 0xf80|(len&0x3f), 12, &olen, &l);
++	} else if (len < 256) {		/* 128 <= length < 256 */
++	    putbits16(obuf, 0x3f00|(len&0x7f), 14, &olen, &l);
++	} else if (len < 512) {		/* 256 <= length < 512 */
++	    putbits16(obuf, 0xfe00|(len&0xff), 16, &olen, &l);
++	} else if (len < 1024) {	/* 512 <= length < 1024 */
++	    putbits24(obuf, 0x3fc00|(len&0x1ff), 18, &olen, &l);
++	} else if (len < 2048) {	/* 1024 <= length < 2048 */
++	    putbits24(obuf, 0xff800|(len&0x3ff), 20, &olen, &l);
++	} else if (len < 4096) {	/* 2048 <= length < 4096 */
++	    putbits24(obuf, 0x3ff000|(len&0x7ff), 22, &olen, &l);
++	} else if (len < 8192) {	/* 4096 <= length < 8192 */
++	    putbits24(obuf, 0xffe000|(len&0xfff), 24, &olen, &l);
++	} else {
++	    /* This shouldn't happen; we return 0 what means "packet expands",
++	    and send packet uncompressed. */
++	    if (state->debug)
++		printk(KERN_DEBUG "%s%d: wrong length of match value: %d\n",
++		       __FUNCTION__, state->unit, len);
++	    return 0;
++	}
++    }
++
++    /* Add remaining octets to the output */
++    while(isize - i > 0) {
++	if (ibuf[i] < 0x80) {	/* literal byte < 0x80 */
++	    putbits8(obuf, (u32) ibuf[i++], 8, &olen, &l);
++	} else {		/* literal byte >= 0x80 */
++	    putbits16(obuf, (u32) (0x100|(ibuf[i++]&0x7f)), 9, &olen, &l);
++	}
++    }
++    /* Reset unused bits of the last output octet */
++    if ((l != 0) && (l != 8)) {
++	putbits8(obuf, 0, l, &olen, &l);
++    }
++
++    return (int) olen;
++}
++
++int
++mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf,
++	      int isize, int osize)
++{
++    struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
++    int proto, olen, complen, off;
++    unsigned char *wptr;
++
++    /* Check that the protocol is in the range we handle. */
++    proto = PPP_PROTOCOL(ibuf);
++    if (proto < 0x0021 || proto > 0x00fa)
++	return 0;
++
++    wptr = obuf;
++    /* Copy over the PPP header */
++    wptr[0] = PPP_ADDRESS(ibuf);
++    wptr[1] = PPP_CONTROL(ibuf);
++    wptr[2] = PPP_COMP >> 8;
++    wptr[3] = PPP_COMP;
++    wptr += PPP_HDRLEN + (MPPE_OVHD / 2); /* Leave two octets for MPPE/MPPC bits */
++
++    /* 
++     * In ver. 0.99 protocol field was compressed. Deflate and BSD compress
++     * do PFC before actual compression, RCF2118 and RFC3078 are not precise
++     * on this topic so I decided to do PFC. Unfortunately this change caused
++     * incompatibility with older/other MPPE/MPPC modules. I have received
++     * a lot of complaints from unexperienced users so I have decided to revert
++     * to previous state, i.e. the protocol field is sent uncompressed now.
++     * Although this may be changed in the future.
++     *
++     * Receiving side (mppe_decompress()) still accepts packets with compressed
++     * and uncompressed protocol field so you shouldn't get "Unsupported protocol
++     * 0x2145 received" messages anymore.
++     */
++    //off = (proto > 0xff) ? 2 : 3; /* PFC - skip first protocol byte if 0 */
++    off = 2;
++
++    ibuf += off;
++
++    mppe_increase_ccount(state);
++
++    if (state->nextflushed) {
++	state->bits |= MPPE_BIT_FLUSHED;
++	state->nextflushed = 0;
++	if (state->mppe && !state->stateless) {
++	    /*
++	     * If this is the flag packet, the key has been already changed in
++	     * mppe_increase_ccount() so we dont't do it once again.
++	     */
++	    if ((state->ccount & 0xff) != 0xff) {
++		arc4_setkey(state, state->session_key, state->keylen);
++	    }
++	}
++	if (state->mppc) { /* reset history */
++	    state->bits |= MPPE_BIT_RESET;
++	    state->histptr = MPPE_HIST_LEN;
++	    memset(state->hist + MPPE_HIST_LEN, 0, MPPE_HIST_LEN*sizeof(u8));
++	}
++    }
++
++    if (state->mppc && !state->mppe) { /* Do only compression */
++	complen = mppc_compress(state, ibuf, wptr, isize - off,
++				osize - PPP_HDRLEN - (MPPE_OVHD / 2));
++	/*
++	 * TODO: Implement an heuristics to handle packet expansion in a smart
++	 * way. Now, when a packet expands, we send it as uncompressed and
++	 * when next packet is sent we have to reset compressor's history.
++	 * Maybe it would be better to send such packet as compressed in order
++	 * to keep history's continuity.
++	 */
++	if ((complen > isize) || (complen > osize - PPP_HDRLEN) ||
++	    (complen == 0)) {
++	    /* packet expands */
++	    state->nextflushed = 1;
++	    memcpy(wptr, ibuf, isize - off);
++	    olen = isize - (off - 2) + MPPE_OVHD;
++	    (state->stats).inc_bytes += olen;
++	    (state->stats).inc_packets++;
++	} else {
++	    state->bits |= MPPE_BIT_COMP;
++	    olen = complen + PPP_HDRLEN + (MPPE_OVHD / 2);
++	    (state->stats).comp_bytes += olen;
++	    (state->stats).comp_packets++;
++	}
++    } else { /* Do encryption with or without compression */
++	state->bits |= MPPE_BIT_ENCRYPTED;
++	if (!state->mppc && state->mppe) { /* Do only encryption */
++	    /* read from ibuf, write to wptr, adjust for PPP_HDRLEN */
++	    arc4_encrypt(state, ibuf, isize - off, wptr);
++	    olen = isize - (off - 2) + MPPE_OVHD;
++	    (state->stats).inc_bytes += olen;
++	    (state->stats).inc_packets++;
++	} else { /* Do compression and then encryption - RFC3078 */
++	    complen = mppc_compress(state, ibuf, wptr, isize - off,
++				    osize - PPP_HDRLEN - (MPPE_OVHD / 2));
++	    /*
++	     * TODO: Implement an heuristics to handle packet expansion in a smart
++	     * way. Now, when a packet expands, we send it as uncompressed and
++	     * when next packet is sent we have to reset compressor's history.
++	     * Maybe it would be good to send such packet as compressed in order
++	     * to keep history's continuity.
++	     */
++	    if ((complen > isize) || (complen > osize - PPP_HDRLEN) ||
++		(complen == 0)) {
++		/* packet expands */
++		state->nextflushed = 1;
++		arc4_encrypt(state, ibuf, isize - off, wptr);
++		olen = isize - (off - 2) + MPPE_OVHD;
++		(state->stats).inc_bytes += olen;
++		(state->stats).inc_packets++;
++	    } else {
++		state->bits |= MPPE_BIT_COMP;
++		/* Hack warning !!! RC4 implementation which we use does
++		   encryption "in place" - it means that input and output
++		   buffers can be *the same* memory area. Therefore we don't
++		   need to use a temporary buffer. But be careful - other
++		   implementations don't have to be so nice.
++		   I used to use ibuf as temporary buffer here, but it led
++		   packet sniffers into error. Thanks to Wilfried Weissmann
++		   for pointing that. */
++		arc4_encrypt(state, wptr, complen, wptr);
++		olen = complen + PPP_HDRLEN + (MPPE_OVHD / 2);
++		(state->stats).comp_bytes += olen;
++		(state->stats).comp_packets++;
++	    }
++	}
++    }
++
++    /* write status bits and coherency counter into the output buffer */
++    wptr = obuf + PPP_HDRLEN;
++    wptr[0] = MPPE_CTRLHI(state);
++    wptr[1] = MPPE_CTRLLO(state);
++
++    state->bits = 0;
++
++    (state->stats).unc_bytes += isize;
++    (state->stats).unc_packets++;
++
++    return olen;
++}
++
++/***************************/
++/*** Decompression stuff ***/
++/***************************/
++static inline u32 getbits(const u8 *buf, const u32 n, u32 *i, u32 *l)
++{
++    static const u32 m[] = {0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff};
++    u32 res, ol;
++
++    ol = *l;
++    if (*l >= n) {
++	*l = (*l) - n;
++	res = (buf[*i] & m[ol]) >> (*l);
++	if (*l == 0) {
++	    *l = 8;
++	    (*i)++;
++	}
++    } else {
++	*l = 8 - n + (*l);
++	res = (buf[(*i)++] & m[ol]) << 8;
++	res = (res | buf[*i]) >> (*l);
++    }
++
++    return res;
++}
++
++static inline u32 getbyte(const u8 *buf, const u32 i, const u32 l)
++{
++    if (l == 8) {
++	return buf[i];
++    } else {
++	return (((buf[i] << 8) | buf[i+1]) >> l) & 0xff;
++    }
++}
++
++static inline void lamecopy(u8 *dst, u8 *src, u32 len)
++{
++    while (len--)
++	*dst++ = *src++;
++}
++
++static int
++mppc_decompress(struct ppp_mppe_state *state, unsigned char *ibuf,
++		unsigned char *obuf, int isize, int osize)
++{
++    u32 olen, off, len, bits, val, sig, i, l;
++    u8 *history, *s;
++
++    history = state->hist + state->histptr;
++    olen = len = i = 0;
++    l = 8;
++    bits = isize * 8;
++    while (bits >= 8) {
++	val = getbyte(ibuf, i++, l);
++	if (val < 0x80) {		/* literal byte < 0x80 */
++	    if (state->histptr < 2*MPPE_HIST_LEN) {
++		/* copy uncompressed byte to the history */
++		(state->hist)[(state->histptr)++] = (u8) val;
++	    } else {
++		/* buffer overflow; drop packet */
++		if (state->debug)
++		    printk(KERN_ERR "%s%d: trying to write outside history "
++			   "buffer\n", __FUNCTION__, state->unit);
++		return DECOMP_ERROR;
++	    }
++	    olen++;
++	    bits -= 8;
++	    continue;
++	}
++
++	sig = val & 0xc0;
++	if (sig == 0x80) {		/* literal byte >= 0x80 */
++	    if (state->histptr < 2*MPPE_HIST_LEN) {
++		/* copy uncompressed byte to the history */
++		(state->hist)[(state->histptr)++] = 
++		    (u8) (0x80|((val&0x3f)<<1)|getbits(ibuf, 1 , &i ,&l));
++	    } else {
++		/* buffer overflow; drop packet */
++		if (state->debug)
++		    printk(KERN_ERR "%s%d: trying to write outside history "
++			   "buffer\n", __FUNCTION__, state->unit);
++		return DECOMP_ERROR;
++	    }
++	    olen++;
++	    bits -= 9;
++	    continue;
++	}
++
++	/* Not a literal byte so it must be an (offset,length) pair */
++	/* decode offset */
++	sig = val & 0xf0;
++	if (sig == 0xf0) {		/* 10-bit offset; 0 <= offset < 64 */
++	    off = (((val&0x0f)<<2)|getbits(ibuf, 2 , &i ,&l));
++	    bits -= 10;
++	} else {
++	    if (sig == 0xe0) {		/* 12-bit offset; 64 <= offset < 320 */
++		off = ((((val&0x0f)<<4)|getbits(ibuf, 4 , &i ,&l))+64);
++		bits -= 12;
++	    } else {
++		if ((sig&0xe0) == 0xc0) {/* 16-bit offset; 320 <= offset < 8192 */
++		    off = ((((val&0x1f)<<8)|getbyte(ibuf, i++, l))+320);
++		    bits -= 16;
++		    if (off > MPPE_HIST_LEN - 1) {
++			if (state->debug)
++			    printk(KERN_DEBUG "%s%d: too big offset value: %d\n",
++				   __FUNCTION__, state->unit, off);
++			return DECOMP_ERROR;
++		    }
++		} else {		/* this shouldn't happen */
++		    if (state->debug)
++			printk(KERN_DEBUG "%s%d: cannot decode offset value\n",
++			       __FUNCTION__, state->unit);
++		    return DECOMP_ERROR;
++		}
++	    }
++	}
++	/* decode length of match */
++	val = getbyte(ibuf, i, l);
++	if ((val & 0x80) == 0x00) {			/* len = 3 */
++	    len = 3;
++	    bits--;
++	    getbits(ibuf, 1 , &i ,&l);
++	} else if ((val & 0xc0) == 0x80) {		/* 4 <= len < 8 */
++	    len = 0x04 | ((val>>4) & 0x03);
++	    bits -= 4;
++	    getbits(ibuf, 4 , &i ,&l);
++	} else if ((val & 0xe0) == 0xc0) {		/* 8 <= len < 16 */
++	    len = 0x08 | ((val>>2) & 0x07);
++	    bits -= 6;
++	    getbits(ibuf, 6 , &i ,&l);
++	} else if ((val & 0xf0) == 0xe0) {		/* 16 <= len < 32 */
++	    len = 0x10 | (val & 0x0f);
++	    bits -= 8;
++	    i++;
++	} else {
++	    bits -= 8;
++	    val = (val << 8) | getbyte(ibuf, ++i, l);
++	    if ((val & 0xf800) == 0xf000) {		/* 32 <= len < 64 */
++		len = 0x0020 | ((val >> 6) & 0x001f);
++		bits -= 2;
++		getbits(ibuf, 2 , &i ,&l);
++	    } else if ((val & 0xfc00) == 0xf800) {	/* 64 <= len < 128 */
++		len = 0x0040 | ((val >> 4) & 0x003f);
++		bits -= 4;
++		getbits(ibuf, 4 , &i ,&l);
++	    } else if ((val & 0xfe00) == 0xfc00) {	/* 128 <= len < 256 */
++		len = 0x0080 | ((val >> 2) & 0x007f);
++		bits -= 6;
++		getbits(ibuf, 6 , &i ,&l);
++	    } else if ((val & 0xff00) == 0xfe00) {	/* 256 <= len < 512 */
++		len = 0x0100 | (val & 0x00ff);
++		bits -= 8;
++		i++;
++	    } else {
++		bits -= 8;
++		val = (val << 8) | getbyte(ibuf, ++i, l);
++		if ((val & 0xff8000) == 0xff0000) {	/* 512 <= len < 1024 */
++		    len = 0x000200 | ((val >> 6) & 0x0001ff);
++		    bits -= 2;
++		    getbits(ibuf, 2 , &i ,&l);
++		} else if ((val & 0xffc000) == 0xff8000) {/* 1024 <= len < 2048 */
++		    len = 0x000400 | ((val >> 4) & 0x0003ff);
++		    bits -= 4;
++		    getbits(ibuf, 4 , &i ,&l);
++		} else if ((val & 0xffe000) == 0xffc000) {/* 2048 <= len < 4096 */
++		    len = 0x000800 | ((val >> 2) & 0x0007ff);
++		    bits -= 6;
++		    getbits(ibuf, 6 , &i ,&l);
++		} else if ((val & 0xfff000) == 0xffe000) {/* 4096 <= len < 8192 */
++		    len = 0x001000 | (val & 0x000fff);
++		    bits -= 8;
++		    i++;
++		} else {				/* this shouldn't happen */
++		    if (state->debug)
++			printk(KERN_DEBUG "%s%d: wrong length code: 0x%X\n",
++			       __FUNCTION__, state->unit, val);
++		    return DECOMP_ERROR;
++		}
++	    }
++	}
++	s = state->hist + state->histptr;
++	state->histptr += len;
++	olen += len;
++	if (state->histptr < 2*MPPE_HIST_LEN) {
++	    /* copy uncompressed bytes to the history */
++
++	    /* In some cases len may be greater than off. It means that memory
++	     * areas pointed by s and s-off overlap. I had used memmove() here
++	     * because I thought that it acts as libc's version. Unfortunately,
++	     * I was wrong. :-) I got strange errors sometimes. Wilfried suggested
++	     * using of byte by byte copying here and strange errors disappeared.
++	     */
++	    lamecopy(s, s - off, len);
++	} else {
++	    /* buffer overflow; drop packet */
++	    if (state->debug)
++		printk(KERN_ERR "%s%d: trying to write outside history "
++		       "buffer\n", __FUNCTION__, state->unit);
++	    return DECOMP_ERROR;
++	}
++    }
++
++    /* Do PFC decompression */
++    len = olen;
++    if ((history[0] & 0x01) != 0) {
++	obuf[0] = 0;
++	obuf++;
++	len++;
++    }
++
++    if (len <= osize) {
++	/* copy uncompressed packet to the output buffer */
++	memcpy(obuf, history, olen);
++    } else {
++	/* buffer overflow; drop packet */
++	if (state->debug)
++	    printk(KERN_ERR "%s%d: too big uncompressed packet: %d\n",
++		   __FUNCTION__, state->unit, len + (PPP_HDRLEN / 2));
++	return DECOMP_ERROR;
++    }
++
++    return (int) len;
++}
++
++int
++mppe_decompress(void *arg, unsigned char *ibuf, int isize,
++		unsigned char *obuf, int osize)
++{
++    struct ppp_mppe_state *state = (struct ppp_mppe_state *)arg;
++    int seq, bits, uncomplen;
++
++    if (isize <= PPP_HDRLEN + MPPE_OVHD) {
++	if (state->debug) {
++	    printk(KERN_DEBUG "%s%d: short packet (len=%d)\n",  __FUNCTION__,
++		   state->unit, isize);
++	}
++	return DECOMP_ERROR;
++    }
++
++    /* Get coherency counter and control bits from input buffer */
++    seq = MPPE_CCOUNT(ibuf);
++    bits = MPPE_BITS(ibuf);
++
++    if (state->stateless) {
++	/* RFC 3078, sec 8.1. */
++	mppe_increase_ccount(state);
++	if ((seq != state->ccount) && state->debug)
++	    printk(KERN_DEBUG "%s%d: bad sequence number: %d, expected: %d\n",
++		   __FUNCTION__, state->unit, seq, state->ccount);
++	while (seq != state->ccount)
++	    mppe_increase_ccount(state);
++    } else {
++	/* RFC 3078, sec 8.2. */
++	if (state->flushexpected) { /* discard state */
++	    if ((bits & MPPE_BIT_FLUSHED)) { /* we received expected FLUSH bit */
++		while (seq != state->ccount)
++		    mppe_increase_ccount(state);
++		state->flushexpected = 0;
++	    } else /* drop packet*/
++		return DECOMP_ERROR;
++	} else { /* normal state */
++	    mppe_increase_ccount(state);
++	    if (seq != state->ccount) {
++		/* Packet loss detected, enter the discard state. */
++		if (state->debug)
++		    printk(KERN_DEBUG "%s%d: bad sequence number: %d, expected: %d\n",
++			   __FUNCTION__, state->unit, seq, state->ccount);
++		state->flushexpected = 1;
++		return DECOMP_ERROR;
++	    }
++	}
++	if (state->mppe && (bits & MPPE_BIT_FLUSHED)) {
++	    arc4_setkey(state, state->session_key, state->keylen);
++	}
++    }
++
++    if (state->mppc && (bits & (MPPE_BIT_FLUSHED | MPPE_BIT_RESET))) {
++	state->histptr = MPPE_HIST_LEN;
++	if ((bits & MPPE_BIT_FLUSHED)) {
++	    memset(state->hist + MPPE_HIST_LEN, 0, MPPE_HIST_LEN*sizeof(u8));
++	} else
++	    if ((bits & MPPE_BIT_RESET)) {
++		memcpy(state->hist, state->hist + MPPE_HIST_LEN, MPPE_HIST_LEN);
++	    }
++    }
++
++    /* Fill in the first part of the PPP header. The protocol field
++       comes from the decompressed data. */
++    obuf[0] = PPP_ADDRESS(ibuf);
++    obuf[1] = PPP_CONTROL(ibuf);
++    obuf += PPP_HDRLEN / 2;
++
++    if (state->mppe) { /* process encrypted packet */
++	if ((bits & MPPE_BIT_ENCRYPTED)) {
++	    /* OK, packet encrypted, so decrypt it */
++	    if (state->mppc && (bits & MPPE_BIT_COMP)) {
++		/* Hack warning !!! RC4 implementation which we use does
++		   decryption "in place" - it means that input and output
++		   buffers can be *the same* memory area. Therefore we don't
++		   need to use a temporary buffer. But be careful - other
++		   implementations don't have to be so nice. */
++		arc4_decrypt(state, ibuf + PPP_HDRLEN +	(MPPE_OVHD / 2), isize -
++			     PPP_HDRLEN - (MPPE_OVHD / 2), ibuf + PPP_HDRLEN +
++			     (MPPE_OVHD / 2));
++		uncomplen = mppc_decompress(state, ibuf + PPP_HDRLEN +
++					    (MPPE_OVHD / 2), obuf, isize -
++					    PPP_HDRLEN - (MPPE_OVHD / 2),
++					    osize - (PPP_HDRLEN / 2));
++		if (uncomplen == DECOMP_ERROR) {
++		    state->flushexpected = 1;
++		    return DECOMP_ERROR;
++		}
++		uncomplen += PPP_HDRLEN / 2;
++		(state->stats).comp_bytes += isize;
++		(state->stats).comp_packets++;
++	    } else {
++		uncomplen = isize - MPPE_OVHD;
++		/* Decrypt the first byte in order to check if it is
++		   compressed or uncompressed protocol field */
++		arc4_decrypt(state, ibuf + PPP_HDRLEN +	(MPPE_OVHD / 2), 1, obuf);
++		/* Do PFC decompression */
++		if ((obuf[0] & 0x01) != 0) {
++		    obuf[1] = obuf[0];
++		    obuf[0] = 0;
++		    obuf++;
++		    uncomplen++;
++		}
++		/* And finally, decrypt the rest of the frame. */
++		arc4_decrypt(state, ibuf + PPP_HDRLEN +	(MPPE_OVHD / 2) + 1,
++			     isize - PPP_HDRLEN - (MPPE_OVHD / 2) - 1, obuf + 1);
++		(state->stats).inc_bytes += isize;
++		(state->stats).inc_packets++;
++	    }
++	} else { /* this shouldn't happen */
++	    if (state->debug)
++		printk(KERN_ERR "%s%d: encryption negotiated but not an "
++		       "encrypted packet received\n", __FUNCTION__, state->unit);
++	    mppe_change_key(state, 0);
++	    state->flushexpected = 1;
++	    return DECOMP_ERROR;
++	}
++    } else {
++	if (state->mppc) { /* no MPPE, only MPPC */
++	    if ((bits & MPPE_BIT_COMP)) {
++		uncomplen = mppc_decompress(state, ibuf + PPP_HDRLEN +
++					    (MPPE_OVHD / 2), obuf, isize -
++					    PPP_HDRLEN - (MPPE_OVHD / 2),
++					    osize - (PPP_HDRLEN / 2));
++		if (uncomplen == DECOMP_ERROR) {
++		    state->flushexpected = 1;
++		    return DECOMP_ERROR;
++		}
++		uncomplen += PPP_HDRLEN / 2;
++		(state->stats).comp_bytes += isize;
++		(state->stats).comp_packets++;
++	    } else {
++		memcpy(obuf, ibuf + PPP_HDRLEN + (MPPE_OVHD / 2), isize -
++		       PPP_HDRLEN - (MPPE_OVHD / 2));
++		uncomplen = isize - MPPE_OVHD;
++		(state->stats).inc_bytes += isize;
++		(state->stats).inc_packets++;
++	    }
++	} else { /* this shouldn't happen */
++	    if (state->debug)
++		printk(KERN_ERR "%s%d: error - not an  MPPC or MPPE frame "
++		       "received\n", __FUNCTION__, state->unit);
++	    state->flushexpected = 1;
++	    return DECOMP_ERROR;
++	}
++    }
++
++    (state->stats).unc_bytes += uncomplen;
++    (state->stats).unc_packets++;
++
++    return uncomplen;
++}
++
++
++/************************************************************
++ * Module interface table
++ ************************************************************/
++
++/* These are in ppp_generic.c */
++extern int  ppp_register_compressor   (struct compressor *cp);
++extern void ppp_unregister_compressor (struct compressor *cp);
++
++/*
++ * Functions exported to ppp_generic.c.
++ *
++ * In case of MPPC/MPPE there is no need to process incompressible data
++ * because such a data is sent in MPPC/MPPE frame. Therefore the (*incomp)
++ * callback function isn't needed.
++ */
++struct compressor ppp_mppe = {
++    .compress_proto =	CI_MPPE,
++    .comp_alloc =	mppe_comp_alloc,
++    .comp_free =	mppe_comp_free,
++    .comp_init =	mppe_comp_init,
++    .comp_reset =	mppe_comp_reset,
++    .compress =		mppe_compress,
++    .comp_stat =	mppe_stats,
++    .decomp_alloc =	mppe_decomp_alloc,
++    .decomp_free =	mppe_comp_free,
++    .decomp_init =	mppe_decomp_init,
++    .decomp_reset =	mppe_decomp_reset,
++    .decompress =	mppe_decompress,
++    .incomp =		NULL,
++    .decomp_stat =	mppe_stats,
++    .owner =		THIS_MODULE
++};
++
++/************************************************************
++ * Module support routines
++ ************************************************************/
++
++int __init mppe_module_init(void)
++{
++    int answer;
++
++    if (!(crypto_alg_available("arc4", 0) && crypto_alg_available("sha1", 0))) {
++	printk(KERN_ERR "Kernel doesn't provide ARC4 and/or SHA1 algorithms "
++	       "required by MPPE/MPPC. Check CryptoAPI configuration.\n");
++	return -ENODEV;
++    }
++
++    /* Allocate space for SHAPad1, SHAPad2 and ... */
++    sha_pad = kmalloc(sizeof(struct sha_pad), GFP_KERNEL);
++    if (sha_pad == NULL)
++	return -ENOMEM;
++    /* ... initialize them */
++    memset(sha_pad->sha_pad1, 0x00, sizeof(sha_pad->sha_pad1));
++    memset(sha_pad->sha_pad2, 0xf2, sizeof(sha_pad->sha_pad2));
++
++    answer = ppp_register_compressor(&ppp_mppe);
++    if (answer == 0) {
++	printk(KERN_INFO "MPPE/MPPC encryption/compression module registered\n");
++    }
++    return answer;
++}
++
++void __exit mppe_module_cleanup(void)
++{
++    kfree(sha_pad);
++    ppp_unregister_compressor(&ppp_mppe);
++    printk(KERN_INFO "MPPE/MPPC encryption/compression module unregistered\n");
++}
++
++module_init(mppe_module_init);
++module_exit(mppe_module_cleanup);
++
++MODULE_AUTHOR("Jan Dubiec <jdx@slackware.pl>");
++MODULE_DESCRIPTION("MPPE/MPPC encryption/compression module for Linux");
++MODULE_VERSION("1.3");
++MODULE_LICENSE("Dual BSD/GPL");
++MODULE_ALIAS("ppp-compress-" __stringify(CI_MPPE));
+--- a/include/linux/crypto.h
++++ b/include/linux/crypto.h
+@@ -309,7 +309,18 @@ int crypto_unregister_alg(struct crypto_
+ /*
+  * Algorithm query interface.
+  */
++#ifdef CONFIG_CRYPTO
++int crypto_alg_available(const char *name, u32 flags)
++	__deprecated_for_modules;
+ int crypto_has_alg(const char *name, u32 type, u32 mask);
++#else
++static int crypto_alg_available(const char *name, u32 flags)
++	__deprecated_for_modules;
++static inline int crypto_has_alg(const char *name, u32 type, u32 mask)
++{
++	return 0;
++}
++#endif
+ 
+ /*
+  * Transforms: user-instantiated objects which encapsulate algorithms
+@@ -1101,6 +1112,16 @@ static inline void crypto_cipher_decrypt
+ 						dst, src);
+ }
+ 
++void crypto_digest_init(struct crypto_tfm *tfm) __deprecated_for_modules;
++void crypto_digest_update(struct crypto_tfm *tfm,
++			  struct scatterlist *sg, unsigned int nsg)
++	__deprecated_for_modules;
++void crypto_digest_final(struct crypto_tfm *tfm, u8 *out)
++	__deprecated_for_modules;
++void crypto_digest_digest(struct crypto_tfm *tfm,
++			  struct scatterlist *sg, unsigned int nsg, u8 *out)
++	__deprecated_for_modules;
++
+ static inline struct crypto_hash *__crypto_hash_cast(struct crypto_tfm *tfm)
+ {
+ 	return (struct crypto_hash *)tfm;
+@@ -1113,6 +1134,14 @@ static inline struct crypto_hash *crypto
+ 	return __crypto_hash_cast(tfm);
+ }
+ 
++static int crypto_digest_setkey(struct crypto_tfm *tfm, const u8 *key,
++				unsigned int keylen) __deprecated;
++static inline int crypto_digest_setkey(struct crypto_tfm *tfm,
++                                       const u8 *key, unsigned int keylen)
++{
++	return tfm->crt_hash.setkey(crypto_hash_cast(tfm), key, keylen);
++}
++
+ static inline struct crypto_hash *crypto_alloc_hash(const char *alg_name,
+ 						    u32 type, u32 mask)
+ {
+--- a/include/linux/ppp-comp.h
++++ b/include/linux/ppp-comp.h
+@@ -26,7 +26,7 @@
+  */
+ 
+ /*
+- *  ==FILEVERSION 980319==
++ *  ==FILEVERSION 20040509==
+  *
+  *  NOTE TO MAINTAINERS:
+  *     If you modify this file at all, please set the above date.
+@@ -78,7 +78,7 @@ struct compressor {
+ 
+ 	/* Compress a packet */
+ 	int     (*compress) (void *state, unsigned char *rptr,
+-			      unsigned char *obuf, int isize, int osize);
++			     unsigned char *obuf, int isize, int osize);
+ 
+ 	/* Return compression statistics */
+ 	void	(*comp_stat) (void *state, struct compstat *stats);
+@@ -99,7 +99,7 @@ struct compressor {
+ 
+ 	/* Decompress a packet. */
+ 	int	(*decompress) (void *state, unsigned char *ibuf, int isize,
+-				unsigned char *obuf, int osize);
++			       unsigned char *obuf, int osize);
+ 
+ 	/* Update state for an incompressible packet received */
+ 	void	(*incomp) (void *state, unsigned char *ibuf, int icnt);
+@@ -109,8 +109,6 @@ struct compressor {
+ 
+ 	/* Used in locking compressor modules */
+ 	struct module *owner;
+-	/* Extra skb space needed by the compressor algorithm */
+-	unsigned int comp_extra;
+ };
+ 
+ /*
+@@ -191,11 +189,40 @@ struct compressor {
+ #define DEFLATE_CHK_SEQUENCE	0
+ 
+ /*
+- * Definitions for MPPE.
++ * Definitions for MPPE/MPPC.
+  */
+ 
+-#define CI_MPPE                18      /* config option for MPPE */
+-#define CILEN_MPPE              6      /* length of config option */
++#define CI_MPPE			18	/* config option for MPPE */
++#define CILEN_MPPE		6	/* length of config option */
++
++#define MPPE_OVHD		4	/* MPPE overhead */
++#define MPPE_MAX_KEY_LEN	16	/* largest key length (128-bit) */
++
++#define MPPE_STATELESS          0x01	/* configuration bit H */
++#define MPPE_40BIT              0x20	/* configuration bit L */
++#define MPPE_56BIT              0x80	/* configuration bit M */
++#define MPPE_128BIT             0x40	/* configuration bit S */
++#define MPPE_MPPC               0x01	/* configuration bit C */
++
++/*
++ * Definitions for Stac LZS.
++ */
++
++#define CI_LZS			17	/* config option for Stac LZS */
++#define CILEN_LZS		5	/* length of config option */
++
++#define LZS_OVHD		4	/* max. LZS overhead */
++#define LZS_HIST_LEN		2048	/* LZS history size */
++#define LZS_MAX_CCOUNT		0x0FFF	/* max. coherency counter value */
++
++#define LZS_MODE_NONE		0
++#define LZS_MODE_LCB		1
++#define LZS_MODE_CRC		2
++#define LZS_MODE_SEQ		3
++#define LZS_MODE_EXT		4
++
++#define LZS_EXT_BIT_FLUSHED	0x80	/* bit A */
++#define LZS_EXT_BIT_COMP	0x20	/* bit C */
+ 
+ /*
+  * Definitions for other, as yet unsupported, compression methods.