[PPP]: add PPP MPPE encryption module
Matt Domsch [Tue, 8 Nov 2005 17:40:47 +0000 (09:40 -0800)]
From: Matt Domsch <Matt_Domsch@dell.com>

The patch below implements the Microsoft Point-to-Point Encryption method
as a PPP compressor/decompressor.  This is necessary for Linux clients and
servers to interoperate with Microsoft Point-to-Point Tunneling Protocol
(PPTP) servers (either Microsoft PPTP servers or the poptop project) which
use MPPE to encrypt data when creating a VPN.

This patch differs from the kernel_ppp_mppe DKMS pacakge at
pptpclient.sourceforge.net by utilizing the kernel crypto routines rather
than providing its own SHA1 and arcfour implementations.

Minor changes to ppp_generic.c try to prevent a link from disabling
compression (in our case, the encryption) after it has started using
compression (encryption).

Feedback to <pptpclient-devel@lists.sourceforge.net> please.

Signed-off-by: Matt Domsch <Matt_Domsch@dell.com>
Cc: James Cameron <james.cameron@hp.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: Brice Goglin <Brice.Goglin@ens-lyon.org>
Acked-by: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/Kconfig
drivers/net/Makefile
drivers/net/ppp_generic.c
drivers/net/ppp_mppe.c [new file with mode: 0644]
drivers/net/ppp_mppe.h [new file with mode: 0644]
include/linux/if_ppp.h
include/linux/ppp-comp.h

index 1958d9e..24f1691 100644 (file)
@@ -2523,6 +2523,19 @@ 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
+       ---help---
+         Support for the MPPE Encryption protocol, as employed by the
+        Microsoft Point-to-Point Tunneling Protocol.
+
+        See http://pptpclient.sourceforge.net/ for information on
+        configuring PPTP clients and servers to utilize this method.
+
 config PPPOE
        tristate "PPP over Ethernet (EXPERIMENTAL)"
        depends on EXPERIMENTAL && PPP
index 7c313cb..4cffd34 100644 (file)
@@ -112,6 +112,7 @@ 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_PPPOE) += pppox.o pppoe.o
 
 obj-$(CONFIG_SLIP) += slip.o
index d3c9958..50430f7 100644 (file)
@@ -137,13 +137,14 @@ 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_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP,
+ * SC_MUST_COMP
  * 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_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP)
 
 /*
  * Private data structure for each channel.
@@ -1027,6 +1028,56 @@ 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,
@@ -1113,29 +1164,14 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
        /* 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);
-               if (new_skb == 0) {
-                       printk(KERN_ERR "PPP: no memory (comp pkt)\n");
+               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");
                        goto drop;
                }
-               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 {
-                       /* didn't compress, or CCP not up yet */
-                       kfree_skb(new_skb);
-               }
+               skb = pad_compress_skb(ppp, skb);
+               if (!skb)
+                       goto drop;
        }
 
        /*
@@ -1155,7 +1191,8 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
        return;
 
  drop:
-       kfree_skb(skb);
+       if (skb)
+               kfree_skb(skb);
        ++ppp->stats.tx_errors;
 }
 
@@ -1552,6 +1589,9 @@ ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb)
            && (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:
diff --git a/drivers/net/ppp_mppe.c b/drivers/net/ppp_mppe.c
new file mode 100644 (file)
index 0000000..1985d1b
--- /dev/null
@@ -0,0 +1,724 @@
+/*
+ * ppp_mppe.c - interface MPPE to the PPP code.
+ * This version is for use with Linux kernel 2.6.14+
+ *
+ * By Frank Cusack <fcusack@fcusack.com>.
+ * Copyright (c) 2002,2003,2004 Google, Inc.
+ * All rights reserved.
+ *
+ * License:
+ * 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.
+ *
+ * ALTERNATIVELY, provided that this notice is retained in full, this product
+ * may be distributed under the terms of the GNU General Public License (GPL),
+ * in which case the provisions of the GPL apply INSTEAD OF those given above.
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ *
+ * Changelog:
+ *      08/12/05 - Matt Domsch <Matt_Domsch@dell.com>
+ *                 Only need extra skb padding on transmit, not receive.
+ *      06/18/04 - Matt Domsch <Matt_Domsch@dell.com>, Oleg Makarenko <mole@quadra.ru>
+ *                 Use Linux kernel 2.6 arc4 and sha1 routines rather than
+ *                 providing our own.
+ *      2/15/04 - TS: added #include <version.h> and testing for Kernel
+ *                    version before using
+ *                    MOD_DEC_USAGE_COUNT/MOD_INC_USAGE_COUNT which are
+ *                    deprecated in 2.6
+ */
+
+#include <linux/config.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/version.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/crypto.h>
+#include <linux/mm.h>
+#include <linux/ppp_defs.h>
+#include <linux/ppp-comp.h>
+#include <asm/scatterlist.h>
+
+#include "ppp_mppe.h"
+
+MODULE_AUTHOR("Frank Cusack <fcusack@fcusack.com>");
+MODULE_DESCRIPTION("Point-to-Point Protocol Microsoft Point-to-Point Encryption support");
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_ALIAS("ppp-compress-" __stringify(CI_MPPE));
+MODULE_VERSION("1.0.2");
+
+static 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;
+}
+
+#define SHA1_PAD_SIZE 40
+
+/*
+ * 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.
+ */
+
+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 sha_pad_init(struct sha_pad *shapad)
+{
+       memset(shapad->sha_pad1, 0x00, sizeof(shapad->sha_pad1));
+       memset(shapad->sha_pad2, 0xF2, sizeof(shapad->sha_pad2));
+}
+
+/*
+ * State for an MPPE (de)compressor.
+ */
+struct ppp_mppe_state {
+       struct crypto_tfm *arc4;
+       struct crypto_tfm *sha1;
+       unsigned char *sha1_digest;
+       unsigned char master_key[MPPE_MAX_KEY_LEN];
+       unsigned char session_key[MPPE_MAX_KEY_LEN];
+       unsigned keylen;        /* key length in bytes             */
+       /* NB: 128-bit == 16, 40-bit == 8! */
+       /* If we want to support 56-bit,   */
+       /* the unit has to change to bits  */
+       unsigned char bits;     /* MPPE control bits */
+       unsigned ccount;        /* 12-bit coherency count (seqno)  */
+       unsigned stateful;      /* stateful mode flag */
+       int discard;            /* stateful mode packet loss flag */
+       int sanity_errors;      /* take down LCP if too many */
+       int unit;
+       int debug;
+       struct compstat stats;
+};
+
+/* struct ppp_mppe_state.bits definitions */
+#define MPPE_BIT_A     0x80    /* Encryption table were (re)inititalized */
+#define MPPE_BIT_B     0x40    /* MPPC only (not implemented) */
+#define MPPE_BIT_C     0x20    /* MPPC only (not implemented) */
+#define MPPE_BIT_D     0x10    /* This is an encrypted frame */
+
+#define MPPE_BIT_FLUSHED       MPPE_BIT_A
+#define MPPE_BIT_ENCRYPTED     MPPE_BIT_D
+
+#define MPPE_BITS(p) ((p)[4] & 0xf0)
+#define MPPE_CCOUNT(p) ((((p)[4] & 0x0f) << 8) + (p)[5])
+#define MPPE_CCOUNT_SPACE 0x1000       /* The size of the ccount space */
+
+#define MPPE_OVHD      2       /* MPPE overhead/packet */
+#define SANITY_MAX     1600    /* Max bogon factor we will tolerate */
+
+/*
+ * 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 *InterimKey)
+{
+       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, sg, 4, state->sha1_digest);
+
+       memcpy(InterimKey, state->sha1_digest, state->keylen);
+}
+
+/*
+ * Perform the MPPE rekey algorithm, from RFC 3078, sec. 7.3.
+ * Well, not what's written there, but rather what they meant.
+ */
+static void mppe_rekey(struct ppp_mppe_state * state, int initial_key)
+{
+       unsigned char InterimKey[MPPE_MAX_KEY_LEN];
+       struct scatterlist sg_in[1], sg_out[1];
+
+       get_new_key_from_sha(state, InterimKey);
+       if (!initial_key) {
+               crypto_cipher_setkey(state->arc4, InterimKey, state->keylen);
+               setup_sg(sg_in, InterimKey, state->keylen);
+               setup_sg(sg_out, state->session_key, state->keylen);
+               if (crypto_cipher_encrypt(state->arc4, sg_out, sg_in,
+                                     state->keylen) != 0) {
+                   printk(KERN_WARNING "mppe_rekey: cipher_encrypt failed\n");
+               }
+       } else {
+               memcpy(state->session_key, InterimKey, state->keylen);
+       }
+       if (state->keylen == 8) {
+               /* See RFC 3078 */
+               state->session_key[0] = 0xd1;
+               state->session_key[1] = 0x26;
+               state->session_key[2] = 0x9e;
+       }
+       crypto_cipher_setkey(state->arc4, state->session_key, state->keylen);
+}
+
+/*
+ * Allocate space for a (de)compressor.
+ */
+static void *mppe_alloc(unsigned char *options, int optlen)
+{
+       struct ppp_mppe_state *state;
+       unsigned int digestsize;
+
+       if (optlen != CILEN_MPPE + sizeof(state->master_key)
+           || options[0] != CI_MPPE || options[1] != CILEN_MPPE)
+               goto out;
+
+       state = (struct ppp_mppe_state *) kmalloc(sizeof(*state), GFP_KERNEL);
+       if (state == NULL)
+               goto out;
+
+       memset(state, 0, sizeof(*state));
+
+       state->arc4 = crypto_alloc_tfm("arc4", 0);
+       if (!state->arc4)
+               goto out_free;
+
+       state->sha1 = crypto_alloc_tfm("sha1", 0);
+       if (!state->sha1)
+               goto out_free;
+
+       digestsize = crypto_tfm_alg_digestsize(state->sha1);
+       if (digestsize < MPPE_MAX_KEY_LEN)
+               goto out_free;
+
+       state->sha1_digest = kmalloc(digestsize, GFP_KERNEL);
+       if (!state->sha1_digest)
+               goto out_free;
+
+       /* Save keys. */
+       memcpy(state->master_key, &options[CILEN_MPPE],
+              sizeof(state->master_key));
+       memcpy(state->session_key, state->master_key,
+              sizeof(state->master_key));
+
+       /*
+        * We defer initial key generation until mppe_init(), as mppe_alloc()
+        * is called frequently during negotiation.
+        */
+
+       return (void *)state;
+
+       out_free:
+           if (state->sha1_digest)
+               kfree(state->sha1_digest);
+           if (state->sha1)
+               crypto_free_tfm(state->sha1);
+           if (state->arc4)
+               crypto_free_tfm(state->arc4);
+           kfree(state);
+       out:
+       return NULL;
+}
+
+/*
+ * Deallocate space for a (de)compressor.
+ */
+static void mppe_free(void *arg)
+{
+       struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
+       if (state) {
+           if (state->sha1_digest)
+               kfree(state->sha1_digest);
+           if (state->sha1)
+               crypto_free_tfm(state->sha1);
+           if (state->arc4)
+               crypto_free_tfm(state->arc4);
+           kfree(state);
+       }
+}
+
+/*
+ * Initialize (de)compressor state.
+ */
+static int
+mppe_init(void *arg, unsigned char *options, int optlen, int unit, int debug,
+         const char *debugstr)
+{
+       struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
+       unsigned char mppe_opts;
+
+       if (optlen != CILEN_MPPE
+           || options[0] != CI_MPPE || options[1] != CILEN_MPPE)
+               return 0;
+
+       MPPE_CI_TO_OPTS(&options[2], mppe_opts);
+       if (mppe_opts & MPPE_OPT_128)
+               state->keylen = 16;
+       else if (mppe_opts & MPPE_OPT_40)
+               state->keylen = 8;
+       else {
+               printk(KERN_WARNING "%s[%d]: unknown key length\n", debugstr,
+                      unit);
+               return 0;
+       }
+       if (mppe_opts & MPPE_OPT_STATEFUL)
+               state->stateful = 1;
+
+       /* Generate the initial session key. */
+       mppe_rekey(state, 1);
+
+       if (debug) {
+               int i;
+               char mkey[sizeof(state->master_key) * 2 + 1];
+               char skey[sizeof(state->session_key) * 2 + 1];
+
+               printk(KERN_DEBUG "%s[%d]: initialized with %d-bit %s mode\n",
+                      debugstr, unit, (state->keylen == 16) ? 128 : 40,
+                      (state->stateful) ? "stateful" : "stateless");
+
+               for (i = 0; i < sizeof(state->master_key); i++)
+                       sprintf(mkey + i * 2, "%02x", state->master_key[i]);
+               for (i = 0; i < sizeof(state->session_key); i++)
+                       sprintf(skey + i * 2, "%02x", state->session_key[i]);
+               printk(KERN_DEBUG
+                      "%s[%d]: keys: master: %s initial session: %s\n",
+                      debugstr, unit, mkey, skey);
+       }
+
+       /*
+        * Initialize the coherency count.  The initial value is not specified
+        * in RFC 3078, but we can make a reasonable assumption that it will
+        * start at 0.  Setting it to the max here makes the comp/decomp code
+        * do the right thing (determined through experiment).
+        */
+       state->ccount = MPPE_CCOUNT_SPACE - 1;
+
+       /*
+        * Note that even though we have initialized the key table, we don't
+        * set the FLUSHED bit.  This is contrary to RFC 3078, sec. 3.1.
+        */
+       state->bits = MPPE_BIT_ENCRYPTED;
+
+       state->unit = unit;
+       state->debug = debug;
+
+       return 1;
+}
+
+static int
+mppe_comp_init(void *arg, unsigned char *options, int optlen, int unit,
+              int hdrlen, int debug)
+{
+       /* ARGSUSED */
+       return mppe_init(arg, options, optlen, unit, debug, "mppe_comp_init");
+}
+
+/*
+ * We received a CCP Reset-Request (actually, we are sending a Reset-Ack),
+ * tell the compressor to rekey.  Note that we MUST NOT rekey for
+ * every CCP Reset-Request; we only rekey on the next xmit packet.
+ * We might get multiple CCP Reset-Requests if our CCP Reset-Ack is lost.
+ * So, rekeying for every CCP Reset-Request is broken as the peer will not
+ * know how many times we've rekeyed.  (If we rekey and THEN get another
+ * CCP Reset-Request, we must rekey again.)
+ */
+static void mppe_comp_reset(void *arg)
+{
+       struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
+
+       state->bits |= MPPE_BIT_FLUSHED;
+}
+
+/*
+ * Compress (encrypt) a packet.
+ * It's strange to call this a compressor, since the output is always
+ * MPPE_OVHD + 2 bytes larger than the input.
+ */
+static 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;
+       struct scatterlist sg_in[1], sg_out[1];
+
+       /*
+        * Check that the protocol is in the range we handle.
+        */
+       proto = PPP_PROTOCOL(ibuf);
+       if (proto < 0x0021 || proto > 0x00fa)
+               return 0;
+
+       /* Make sure we have enough room to generate an encrypted packet. */
+       if (osize < isize + MPPE_OVHD + 2) {
+               /* Drop the packet if we should encrypt it, but can't. */
+               printk(KERN_DEBUG "mppe_compress[%d]: osize too small! "
+                      "(have: %d need: %d)\n", state->unit,
+                      osize, osize + MPPE_OVHD + 2);
+               return -1;
+       }
+
+       osize = isize + MPPE_OVHD + 2;
+
+       /*
+        * Copy over the PPP header and set control bits.
+        */
+       obuf[0] = PPP_ADDRESS(ibuf);
+       obuf[1] = PPP_CONTROL(ibuf);
+       obuf[2] = PPP_COMP >> 8;        /* isize + MPPE_OVHD + 1 */
+       obuf[3] = PPP_COMP;     /* isize + MPPE_OVHD + 2 */
+       obuf += PPP_HDRLEN;
+
+       state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
+       if (state->debug >= 7)
+               printk(KERN_DEBUG "mppe_compress[%d]: ccount %d\n", state->unit,
+                      state->ccount);
+       obuf[0] = state->ccount >> 8;
+       obuf[1] = state->ccount & 0xff;
+
+       if (!state->stateful || /* stateless mode     */
+           ((state->ccount & 0xff) == 0xff) || /* "flag" packet      */
+           (state->bits & MPPE_BIT_FLUSHED)) { /* CCP Reset-Request  */
+               /* We must rekey */
+               if (state->debug && state->stateful)
+                       printk(KERN_DEBUG "mppe_compress[%d]: rekeying\n",
+                              state->unit);
+               mppe_rekey(state, 0);
+               state->bits |= MPPE_BIT_FLUSHED;
+       }
+       obuf[0] |= state->bits;
+       state->bits &= ~MPPE_BIT_FLUSHED;       /* reset for next xmit */
+
+       obuf += MPPE_OVHD;
+       ibuf += 2;              /* skip to proto field */
+       isize -= 2;
+
+       /* Encrypt packet */
+       setup_sg(sg_in, ibuf, isize);
+       setup_sg(sg_out, obuf, osize);
+       if (crypto_cipher_encrypt(state->arc4, sg_out, sg_in, isize) != 0) {
+               printk(KERN_DEBUG "crypto_cypher_encrypt failed\n");
+               return -1;
+       }
+
+       state->stats.unc_bytes += isize;
+       state->stats.unc_packets++;
+       state->stats.comp_bytes += osize;
+       state->stats.comp_packets++;
+
+       return osize;
+}
+
+/*
+ * Since every frame grows by MPPE_OVHD + 2 bytes, this is always going
+ * to look bad ... and the longer the link is up the worse it will get.
+ */
+static void mppe_comp_stats(void *arg, struct compstat *stats)
+{
+       struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
+
+       *stats = state->stats;
+}
+
+static int
+mppe_decomp_init(void *arg, unsigned char *options, int optlen, int unit,
+                int hdrlen, int mru, int debug)
+{
+       /* ARGSUSED */
+       return mppe_init(arg, options, optlen, unit, debug, "mppe_decomp_init");
+}
+
+/*
+ * We received a CCP Reset-Ack.  Just ignore it.
+ */
+static void mppe_decomp_reset(void *arg)
+{
+       /* ARGSUSED */
+       return;
+}
+
+/*
+ * Decompress (decrypt) an MPPE packet.
+ */
+static 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;
+       unsigned ccount;
+       int flushed = MPPE_BITS(ibuf) & MPPE_BIT_FLUSHED;
+       int sanity = 0;
+       struct scatterlist sg_in[1], sg_out[1];
+
+       if (isize <= PPP_HDRLEN + MPPE_OVHD) {
+               if (state->debug)
+                       printk(KERN_DEBUG
+                              "mppe_decompress[%d]: short pkt (%d)\n",
+                              state->unit, isize);
+               return DECOMP_ERROR;
+       }
+
+       /*
+        * Make sure we have enough room to decrypt the packet.
+        * Note that for our test we only subtract 1 byte whereas in
+        * mppe_compress() we added 2 bytes (+MPPE_OVHD);
+        * this is to account for possible PFC.
+        */
+       if (osize < isize - MPPE_OVHD - 1) {
+               printk(KERN_DEBUG "mppe_decompress[%d]: osize too small! "
+                      "(have: %d need: %d)\n", state->unit,
+                      osize, isize - MPPE_OVHD - 1);
+               return DECOMP_ERROR;
+       }
+       osize = isize - MPPE_OVHD - 2;  /* assume no PFC */
+
+       ccount = MPPE_CCOUNT(ibuf);
+       if (state->debug >= 7)
+               printk(KERN_DEBUG "mppe_decompress[%d]: ccount %d\n",
+                      state->unit, ccount);
+
+       /* sanity checks -- terminate with extreme prejudice */
+       if (!(MPPE_BITS(ibuf) & MPPE_BIT_ENCRYPTED)) {
+               printk(KERN_DEBUG
+                      "mppe_decompress[%d]: ENCRYPTED bit not set!\n",
+                      state->unit);
+               state->sanity_errors += 100;
+               sanity = 1;
+       }
+       if (!state->stateful && !flushed) {
+               printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set in "
+                      "stateless mode!\n", state->unit);
+               state->sanity_errors += 100;
+               sanity = 1;
+       }
+       if (state->stateful && ((ccount & 0xff) == 0xff) && !flushed) {
+               printk(KERN_DEBUG "mppe_decompress[%d]: FLUSHED bit not set on "
+                      "flag packet!\n", state->unit);
+               state->sanity_errors += 100;
+               sanity = 1;
+       }
+
+       if (sanity) {
+               if (state->sanity_errors < SANITY_MAX)
+                       return DECOMP_ERROR;
+               else
+                       /*
+                        * Take LCP down if the peer is sending too many bogons.
+                        * We don't want to do this for a single or just a few
+                        * instances since it could just be due to packet corruption.
+                        */
+                       return DECOMP_FATALERROR;
+       }
+
+       /*
+        * Check the coherency count.
+        */
+
+       if (!state->stateful) {
+               /* RFC 3078, sec 8.1.  Rekey for every packet. */
+               while (state->ccount != ccount) {
+                       mppe_rekey(state, 0);
+                       state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
+               }
+       } else {
+               /* RFC 3078, sec 8.2. */
+               if (!state->discard) {
+                       /* normal state */
+                       state->ccount = (state->ccount + 1) % MPPE_CCOUNT_SPACE;
+                       if (ccount != state->ccount) {
+                               /*
+                                * (ccount > state->ccount)
+                                * Packet loss detected, enter the discard state.
+                                * Signal the peer to rekey (by sending a CCP Reset-Request).
+                                */
+                               state->discard = 1;
+                               return DECOMP_ERROR;
+                       }
+               } else {
+                       /* discard state */
+                       if (!flushed) {
+                               /* ccp.c will be silent (no additional CCP Reset-Requests). */
+                               return DECOMP_ERROR;
+                       } else {
+                               /* Rekey for every missed "flag" packet. */
+                               while ((ccount & ~0xff) !=
+                                      (state->ccount & ~0xff)) {
+                                       mppe_rekey(state, 0);
+                                       state->ccount =
+                                           (state->ccount +
+                                            256) % MPPE_CCOUNT_SPACE;
+                               }
+
+                               /* reset */
+                               state->discard = 0;
+                               state->ccount = ccount;
+                               /*
+                                * Another problem with RFC 3078 here.  It implies that the
+                                * peer need not send a Reset-Ack packet.  But RFC 1962
+                                * requires it.  Hopefully, M$ does send a Reset-Ack; even
+                                * though it isn't required for MPPE synchronization, it is
+                                * required to reset CCP state.
+                                */
+                       }
+               }
+               if (flushed)
+                       mppe_rekey(state, 0);
+       }
+
+       /*
+        * Fill in the first part of the PPP header.  The protocol field
+        * comes from the decrypted data.
+        */
+       obuf[0] = PPP_ADDRESS(ibuf);    /* +1 */
+       obuf[1] = PPP_CONTROL(ibuf);    /* +1 */
+       obuf += 2;
+       ibuf += PPP_HDRLEN + MPPE_OVHD;
+       isize -= PPP_HDRLEN + MPPE_OVHD;        /* -6 */
+       /* net osize: isize-4 */
+
+       /*
+        * Decrypt the first byte in order to check if it is
+        * a compressed or uncompressed protocol field.
+        */
+       setup_sg(sg_in, ibuf, 1);
+       setup_sg(sg_out, obuf, 1);
+       if (crypto_cipher_decrypt(state->arc4, sg_out, sg_in, 1) != 0) {
+               printk(KERN_DEBUG "crypto_cypher_decrypt failed\n");
+               return DECOMP_ERROR;
+       }
+
+       /*
+        * Do PFC decompression.
+        * This would be nicer if we were given the actual sk_buff
+        * instead of a char *.
+        */
+       if ((obuf[0] & 0x01) != 0) {
+               obuf[1] = obuf[0];
+               obuf[0] = 0;
+               obuf++;
+               osize++;
+       }
+
+       /* And finally, decrypt the rest of the packet. */
+       setup_sg(sg_in, ibuf + 1, isize - 1);
+       setup_sg(sg_out, obuf + 1, osize - 1);
+       if (crypto_cipher_decrypt(state->arc4, sg_out, sg_in, isize - 1) != 0) {
+               printk(KERN_DEBUG "crypto_cypher_decrypt failed\n");
+               return DECOMP_ERROR;
+       }
+
+       state->stats.unc_bytes += osize;
+       state->stats.unc_packets++;
+       state->stats.comp_bytes += isize;
+       state->stats.comp_packets++;
+
+       /* good packet credit */
+       state->sanity_errors >>= 1;
+
+       return osize;
+}
+
+/*
+ * Incompressible data has arrived (this should never happen!).
+ * We should probably drop the link if the protocol is in the range
+ * of what should be encrypted.  At the least, we should drop this
+ * packet.  (How to do this?)
+ */
+static void mppe_incomp(void *arg, unsigned char *ibuf, int icnt)
+{
+       struct ppp_mppe_state *state = (struct ppp_mppe_state *) arg;
+
+       if (state->debug &&
+           (PPP_PROTOCOL(ibuf) >= 0x0021 && PPP_PROTOCOL(ibuf) <= 0x00fa))
+               printk(KERN_DEBUG
+                      "mppe_incomp[%d]: incompressible (unencrypted) data! "
+                      "(proto %04x)\n", state->unit, PPP_PROTOCOL(ibuf));
+
+       state->stats.inc_bytes += icnt;
+       state->stats.inc_packets++;
+       state->stats.unc_bytes += icnt;
+       state->stats.unc_packets++;
+}
+
+/*************************************************************
+ * Module interface table
+ *************************************************************/
+
+/*
+ * Procedures exported to if_ppp.c.
+ */
+static struct compressor ppp_mppe = {
+       .compress_proto = CI_MPPE,
+       .comp_alloc     = mppe_alloc,
+       .comp_free      = mppe_free,
+       .comp_init      = mppe_comp_init,
+       .comp_reset     = mppe_comp_reset,
+       .compress       = mppe_compress,
+       .comp_stat      = mppe_comp_stats,
+       .decomp_alloc   = mppe_alloc,
+       .decomp_free    = mppe_free,
+       .decomp_init    = mppe_decomp_init,
+       .decomp_reset   = mppe_decomp_reset,
+       .decompress     = mppe_decompress,
+       .incomp         = mppe_incomp,
+       .decomp_stat    = mppe_comp_stats,
+       .owner          = THIS_MODULE,
+       .comp_extra     = MPPE_PAD,
+};
+
+/*
+ * ppp_mppe_init()
+ *
+ * Prior to allowing load, try to load the arc4 and sha1 crypto
+ * libraries.  The actual use will be allocated later, but
+ * this way the module will fail to insmod if they aren't available.
+ */
+
+static int __init ppp_mppe_init(void)
+{
+       int answer;
+       if (!(crypto_alg_available("arc4", 0) &&
+             crypto_alg_available("sha1", 0)))
+               return -ENODEV;
+
+       sha_pad = kmalloc(sizeof(struct sha_pad), GFP_KERNEL);
+       if (!sha_pad)
+               return -ENOMEM;
+       sha_pad_init(sha_pad);
+
+       answer = ppp_register_compressor(&ppp_mppe);
+
+       if (answer == 0)
+               printk(KERN_INFO "PPP MPPE Compression module registered\n");
+       else
+               kfree(sha_pad);
+
+       return answer;
+}
+
+static void __exit ppp_mppe_cleanup(void)
+{
+       ppp_unregister_compressor(&ppp_mppe);
+       kfree(sha_pad);
+}
+
+module_init(ppp_mppe_init);
+module_exit(ppp_mppe_cleanup);
diff --git a/drivers/net/ppp_mppe.h b/drivers/net/ppp_mppe.h
new file mode 100644 (file)
index 0000000..7a14e05
--- /dev/null
@@ -0,0 +1,86 @@
+#define MPPE_PAD                4      /* MPPE growth per frame */
+#define MPPE_MAX_KEY_LEN       16      /* largest key length (128-bit) */
+
+/* option bits for ccp_options.mppe */
+#define MPPE_OPT_40            0x01    /* 40 bit */
+#define MPPE_OPT_128           0x02    /* 128 bit */
+#define MPPE_OPT_STATEFUL      0x04    /* stateful mode */
+/* unsupported opts */
+#define MPPE_OPT_56            0x08    /* 56 bit */
+#define MPPE_OPT_MPPC          0x10    /* MPPC compression */
+#define MPPE_OPT_D             0x20    /* Unknown */
+#define MPPE_OPT_UNSUPPORTED (MPPE_OPT_56|MPPE_OPT_MPPC|MPPE_OPT_D)
+#define MPPE_OPT_UNKNOWN       0x40    /* Bits !defined in RFC 3078 were set */
+
+/*
+ * This is not nice ... the alternative is a bitfield struct though.
+ * And unfortunately, we cannot share the same bits for the option
+ * names above since C and H are the same bit.  We could do a u_int32
+ * but then we have to do a htonl() all the time and/or we still need
+ * to know which octet is which.
+ */
+#define MPPE_C_BIT             0x01    /* MPPC */
+#define MPPE_D_BIT             0x10    /* Obsolete, usage unknown */
+#define MPPE_L_BIT             0x20    /* 40-bit */
+#define MPPE_S_BIT             0x40    /* 128-bit */
+#define MPPE_M_BIT             0x80    /* 56-bit, not supported */
+#define MPPE_H_BIT             0x01    /* Stateless (in a different byte) */
+
+/* Does not include H bit; used for least significant octet only. */
+#define MPPE_ALL_BITS (MPPE_D_BIT|MPPE_L_BIT|MPPE_S_BIT|MPPE_M_BIT|MPPE_H_BIT)
+
+/* Build a CI from mppe opts (see RFC 3078) */
+#define MPPE_OPTS_TO_CI(opts, ci)              \
+    do {                                       \
+       u_char *ptr = ci; /* u_char[4] */       \
+                                               \
+       /* H bit */                             \
+       if (opts & MPPE_OPT_STATEFUL)           \
+           *ptr++ = 0x0;                       \
+       else                                    \
+           *ptr++ = MPPE_H_BIT;                \
+       *ptr++ = 0;                             \
+       *ptr++ = 0;                             \
+                                               \
+       /* S,L bits */                          \
+       *ptr = 0;                               \
+       if (opts & MPPE_OPT_128)                \
+           *ptr |= MPPE_S_BIT;                 \
+       if (opts & MPPE_OPT_40)                 \
+           *ptr |= MPPE_L_BIT;                 \
+       /* M,D,C bits not supported */          \
+    } while (/* CONSTCOND */ 0)
+
+/* The reverse of the above */
+#define MPPE_CI_TO_OPTS(ci, opts)              \
+    do {                                       \
+       u_char *ptr = ci; /* u_char[4] */       \
+                                               \
+       opts = 0;                               \
+                                               \
+       /* H bit */                             \
+       if (!(ptr[0] & MPPE_H_BIT))             \
+           opts |= MPPE_OPT_STATEFUL;          \
+                                               \
+       /* S,L bits */                          \
+       if (ptr[3] & MPPE_S_BIT)                \
+           opts |= MPPE_OPT_128;               \
+       if (ptr[3] & MPPE_L_BIT)                \
+           opts |= MPPE_OPT_40;                \
+                                               \
+       /* M,D,C bits */                        \
+       if (ptr[3] & MPPE_M_BIT)                \
+           opts |= MPPE_OPT_56;                \
+       if (ptr[3] & MPPE_D_BIT)                \
+           opts |= MPPE_OPT_D;                 \
+       if (ptr[3] & MPPE_C_BIT)                \
+           opts |= MPPE_OPT_MPPC;              \
+                                               \
+       /* Other bits */                        \
+       if (ptr[0] & ~MPPE_H_BIT)               \
+           opts |= MPPE_OPT_UNKNOWN;           \
+       if (ptr[1] || ptr[2])                   \
+           opts |= MPPE_OPT_UNKNOWN;           \
+       if (ptr[3] & ~MPPE_ALL_BITS)            \
+           opts |= MPPE_OPT_UNKNOWN;           \
+    } while (/* CONSTCOND */ 0)
index 572aff7..768372f 100644 (file)
@@ -21,7 +21,7 @@
  */
 
 /*
- *  ==FILEVERSION 20000724==
+ *  ==FILEVERSION 20050812==
  *
  *  NOTE TO MAINTAINERS:
  *     If you modify this file at all, please set the above date.
@@ -35,6 +35,8 @@
 #ifndef _IF_PPP_H_
 #define _IF_PPP_H_
 
+#include <linux/compiler.h>
+
 /*
  * Packet sizes
  */
@@ -70,7 +72,8 @@
 #define SC_LOG_RAWIN   0x00080000      /* log all chars received */
 #define SC_LOG_FLUSH   0x00100000      /* log all chars flushed */
 #define        SC_SYNC         0x00200000      /* synchronous serial mode */
-#define        SC_MASK         0x0f200fff      /* bits that user can change */
+#define        SC_MUST_COMP    0x00400000      /* no uncompressed packets may be sent or received */
+#define        SC_MASK         0x0f600fff      /* bits that user can change */
 
 /* state bits */
 #define SC_XMIT_BUSY   0x10000000      /* (used by isdn_ppp?) */
index 7227e65..e86a7a5 100644 (file)
@@ -111,6 +111,8 @@ struct compressor {
 
        /* Used in locking compressor modules */
        struct module *owner;
+       /* Extra skb space needed by the compressor algorithm */
+       unsigned int comp_extra;
 };
 
 /*
@@ -191,6 +193,13 @@ struct compressor {
 #define DEFLATE_CHK_SEQUENCE   0
 
 /*
+ * Definitions for MPPE.
+ */
+
+#define CI_MPPE                18      /* config option for MPPE */
+#define CILEN_MPPE              6      /* length of config option */
+
+/*
  * Definitions for other, as yet unsupported, compression methods.
  */