merge of 425cf1b391611c169a1c3b78f1fe86df088902b9

[vuplus_openembedded] / packages / linux / linux-dht-walnut-2.6.12.6 / linux-2.6.12-mppe-mppc-1.3.patch

diff -ruN linux-2.6.12.orig/drivers/net/Kconfig linux-2.6.12/drivers/net/Kconfig
--- linux-2.6.12.orig/drivers/net/Kconfig       2005-06-28 19:57:16.000000000 +0200
+++ linux-2.6.12/drivers/net/Kconfig    2005-06-28 20:07:01.000000000 +0200
@@ -2417,6 +2417,32 @@
          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_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.
+
+         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://free.polbox.pl/h/hs001
+
+         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)"
        depends on EXPERIMENTAL && PPP
diff -ruN linux-2.6.12.orig/drivers/net/Makefile linux-2.6.12/drivers/net/Makefile
--- linux-2.6.12.orig/drivers/net/Makefile      2005-06-28 19:57:16.000000000 +0200
+++ linux-2.6.12/drivers/net/Makefile   2005-06-28 20:07:01.000000000 +0200
@@ -105,6 +105,7 @@
 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_MPPC) += ppp_mppe_mppc.o
 obj-$(CONFIG_PPPOE) += pppox.o pppoe.o
 
 obj-$(CONFIG_SLIP) += slip.o
diff -ruN linux-2.6.12.orig/drivers/net/ppp_generic.c linux-2.6.12/drivers/net/ppp_generic.c
--- linux-2.6.12.orig/drivers/net/ppp_generic.c 2005-06-28 19:57:20.000000000 +0200
+++ linux-2.6.12/drivers/net/ppp_generic.c      2005-06-28 20:07:01.000000000 +0200
@@ -19,7 +19,7 @@
  * PPP driver, written by Michael Callahan and Al Longyear, and
  * subsequently hacked by Paul Mackerras.
  *
- * ==FILEVERSION 20041108==
+ * ==FILEVERSION 20050110==
  */
 
 #include <linux/config.h>
@@ -105,6 +105,7 @@
        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 */
@@ -632,7 +633,9 @@
        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;
 
@@ -1107,14 +1110,37 @@
        case PPP_CCP:
                /* peek at outbound CCP frames */
                ppp_ccp_peek(ppp, skb, 0);
+               /*
+                * When LZS or MPPE/MPPC has been negotiated we don't send
+                * CCP_RESETACK after receiving CCP_RESETREQ; in fact pppd
+                * sends such a packet but we silently discard it here
+                */
+               if (CCP_CODE(skb->data+2) == CCP_RESETACK
+                   && (ppp->xcomp->compress_proto == CI_MPPE
+                       || ppp->xcomp->compress_proto == CI_LZS)) {
+                   --ppp->stats.tx_packets;
+                   ppp->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 != 0
            && proto != PPP_LCP && proto != PPP_CCP) {
-               new_skb = alloc_skb(ppp->dev->mtu + ppp->dev->hard_header_len,
-                                   GFP_ATOMIC);
+               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;
@@ -1132,9 +1158,21 @@
                        skb = new_skb;
                        skb_put(skb, len);
                        skb_pull(skb, 2);       /* pull off A/C bytes */
-               } else {
+               } else if (len == 0) {
                        /* didn't compress, or CCP not up yet */
                        kfree_skb(new_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.
+                        */
+                       printk(KERN_ERR "ppp: compressor dropped pkt\n");
+                       kfree_skb(new_skb);
+                       goto drop;
                }
        }
 
@@ -1640,14 +1678,15 @@
                goto err;
 
        if (proto == PPP_COMP) {
-               ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
+               ns = dev_alloc_skb(ppp->mru_alloc + PPP_HDRLEN);
                if (ns == 0) {
                        printk(KERN_ERR "ppp_decompress_frame: no memory\n");
                        goto err;
                }
                /* the decompressor still expects the A/C bytes in the hdr */
                len = ppp->rcomp->decompress(ppp->rc_state, skb->data - 2,
-                               skb->len + 2, ns->data, ppp->mru + PPP_HDRLEN);
+                               skb->len + 2, ns->data,
+                               ppp->mru_alloc + PPP_HDRLEN);
                if (len < 0) {
                        /* Pass the compressed frame to pppd as an
                           error indication. */
@@ -1673,7 +1712,14 @@
        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;
 }
@@ -2349,6 +2395,7 @@
        memset(ppp, 0, sizeof(struct ppp));
 
        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)
diff -ruN linux-2.6.12.orig/drivers/net/ppp_mppe_mppc.c linux-2.6.12/drivers/net/ppp_mppe_mppc.c
--- linux-2.6.12.orig/drivers/net/ppp_mppe_mppc.c       1970-01-01 01:00:00.000000000 +0100
+++ linux-2.6.12/drivers/net/ppp_mppe_mppc.c    2005-06-28 20:07:01.000000000 +0200
@@ -0,0 +1,1299 @@
+/*
+ * 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_tfm *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 inline void
+setup_sg(struct scatterlist *sg, const void  *address, unsigned int length)
+{
+    sg[0].page = virt_to_page(address);
+    sg[0].offset = offset_in_page(address);
+    sg[0].length = 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)
+{
+    struct scatterlist sgin[4], sgout[4];
+
+    setup_sg(sgin, in, len);
+    setup_sg(sgout, out, len);
+    crypto_cipher_encrypt(state->arc4_tfm, sgout, sgin, len);
+}
+
+#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 scatterlist sg[4];
+
+    setup_sg(&sg[0], state->master_key, state->keylen);
+    setup_sg(&sg[1], sha_pad->sha_pad1, sizeof(sha_pad->sha_pad1));
+    setup_sg(&sg[2], state->session_key, state->keylen);
+    setup_sg(&sg[3], sha_pad->sha_pad2, sizeof(sha_pad->sha_pad2));
+
+    crypto_digest_digest (state->sha1_tfm, sg, 4, 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_tfm("arc4", 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_tfm("sha1", 0);
+       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_tfm_alg_digestsize(state->sha1_tfm);
+       if (digestsize < MPPE_MAX_KEY_LEN) {
+           crypto_free_tfm(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_tfm(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_tfm(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("1.2");
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS("ppp-compress-" __stringify(CI_MPPE));
diff -ruN linux-2.6.12.orig/include/linux/ppp-comp.h linux-2.6.12/include/linux/ppp-comp.h
--- linux-2.6.12.orig/include/linux/ppp-comp.h  2004-12-24 22:33:47.000000000 +0100
+++ linux-2.6.12/include/linux/ppp-comp.h       2005-06-28 20:07:01.000000000 +0200
@@ -28,7 +28,7 @@
  */
 
 /*
- *  ==FILEVERSION 980319==
+ *  ==FILEVERSION 20040509==
  *
  *  NOTE TO MAINTAINERS:
  *     If you modify this file at all, please set the above date.
@@ -80,7 +80,7 @@
 
        /* 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);
@@ -101,7 +101,7 @@
 
        /* 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);
@@ -191,6 +191,42 @@
 #define DEFLATE_CHK_SEQUENCE   0
 
 /*
+ * Definitions for MPPE/MPPC.
+ */
+
+#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.
  */