+++ /dev/null
-/*
- * ppp_mppe_compress.c - interface MPPE to the PPP code.
- * This version is for use with Linux kernel 2.2.19+, 2.4.18+ and 2.6.2+.
- *
- * By Frank Cusack <frank@google.com>.
- * Copyright (c) 2002,2003,2004 Google, Inc.
- * All rights reserved.
- *
- * 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.
- *
- * Changelog:
- * 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/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/ppp_defs.h>
-#include <linux/ppp-comp.h>
-
-#include "arcfour.h"
-#include "sha1.h"
-
-/*
- * State for an MPPE (de)compressor.
- */
-typedef struct ppp_mppe_state {
- unsigned char master_key[MPPE_MAX_KEY_LEN];
- unsigned char session_key[MPPE_MAX_KEY_LEN];
- arcfour_context arcfour_context; /* encryption state */
- 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;
-} ppp_mppe_state;
-
-/* 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 */
-
-static void GetNewKeyFromSHA __P((unsigned char *StartKey,
- unsigned char *SessionKey,
- unsigned SessionKeyLength,
- unsigned char *InterimKey));
-static void mppe_rekey __P((ppp_mppe_state *state, int));
-static void *mppe_alloc __P((unsigned char *options, int optlen));
-static void mppe_free __P((void *state));
-static int mppe_init __P((void *state, unsigned char *options,
- int optlen, int unit, int debug, const char *));
-static int mppe_comp_init __P((void *state, unsigned char *options,
- int optlen,
- int unit, int hdrlen, int debug));
-static int mppe_decomp_init __P((void *state, unsigned char *options,
- int optlen, int unit,
- int hdrlen, int mru, int debug));
-static int mppe_compress __P((void *state, unsigned char *ibuf,
- unsigned char *obuf,
- int isize, int osize));
-static void mppe_incomp __P((void *state, unsigned char *ibuf, int icnt));
-static int mppe_decompress __P((void *state, unsigned char *ibuf,
- int isize, unsigned char *obuf,int osize));
-static void mppe_comp_reset __P((void *state));
-static void mppe_decomp_reset __P((void *state));
-static void mppe_comp_stats __P((void *state, struct compstat *stats));
-
-
-/*
- * Key Derivation, from RFC 3078, RFC 3079.
- * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
- */
-static void
-GetNewKeyFromSHA(unsigned char *MasterKey, unsigned char *SessionKey,
- unsigned SessionKeyLength, unsigned char *InterimKey)
-{
- SHA1_CTX Context;
- unsigned char Digest[SHA1_SIGNATURE_SIZE];
-
- unsigned char SHApad1[40] =
- { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
- 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
- 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
- 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
- unsigned char SHApad2[40] =
- { 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
- 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
- 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2,
- 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2, 0xf2 };
-
- /* assert(SessionKeyLength <= SHA1_SIGNATURE_SIZE); */
-
- SHA1_Init(&Context);
- SHA1_Update(&Context, MasterKey, SessionKeyLength);
- SHA1_Update(&Context, SHApad1, sizeof(SHApad1));
- SHA1_Update(&Context, SessionKey, SessionKeyLength);
- SHA1_Update(&Context, SHApad2, sizeof(SHApad2));
- SHA1_Final(Digest, &Context);
-
- memcpy(InterimKey, Digest, SessionKeyLength);
-}
-
-/*
- * 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(ppp_mppe_state *state, int initial_key)
-{
- unsigned char InterimKey[MPPE_MAX_KEY_LEN];
-
- GetNewKeyFromSHA(state->master_key, state->session_key,
- state->keylen, InterimKey);
- if (!initial_key) {
- arcfour_setkey(&state->arcfour_context, InterimKey, state->keylen);
- arcfour_encrypt(&state->arcfour_context, InterimKey, state->keylen,
- state->session_key);
- } 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;
- }
- arcfour_setkey(&state->arcfour_context, state->session_key, state->keylen);
-}
-
-
-/*
- * Allocate space for a (de)compressor.
- */
-static void *
-mppe_alloc(unsigned char *options, int optlen)
-{
- ppp_mppe_state *state;
-
- if (optlen != CILEN_MPPE + sizeof(state->master_key)
- || options[0] != CI_MPPE
- || options[1] != CILEN_MPPE)
- return NULL;
-
- state = (ppp_mppe_state *) kmalloc(sizeof(*state), GFP_KERNEL);
- if (state == NULL)
- return NULL;
-
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0))
- try_module_get(THIS_MODULE);
-#else
- MOD_INC_USE_COUNT;
-#endif
- memset(state, 0, sizeof(*state));
-
- /* 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;
-}
-
-/*
- * Deallocate space for a (de)compressor.
- */
-static void
-mppe_free(void *arg)
-{
- ppp_mppe_state *state = (ppp_mppe_state *) arg;
-
- if (state) {
- kfree(state);
-#if (LINUX_VERSION_CODE >= KERNEL_VERSION(2,6,0))
- module_put(THIS_MODULE);
-#else
- MOD_DEC_USE_COUNT;
-#endif
- }
-}
-
-
-/*
- * Initialize (de)compressor state.
- */
-static int
-mppe_init(void *arg, unsigned char *options, int optlen, int unit, int debug,
- const char *debugstr)
-{
- ppp_mppe_state *state = (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, "%.2x", state->master_key[i]);
- for (i = 0; i < sizeof(state->session_key); i++)
- sprintf(skey + i * 2, "%.2x", 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)
-{
- ppp_mppe_state *state = (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.
- */
-int
-mppe_compress(void *arg, unsigned char *ibuf, unsigned char *obuf,
- int isize, int osize)
-{
- ppp_mppe_state *state = (ppp_mppe_state *) arg;
- int proto;
-
- /*
- * 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 */
- arcfour_encrypt(&state->arcfour_context, ibuf, isize, obuf);
-
- 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)
-{
- ppp_mppe_state *state = (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.
- */
-int
-mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
- int osize)
-{
- ppp_mppe_state *state = (ppp_mppe_state *) arg;
- unsigned ccount;
- int flushed = MPPE_BITS(ibuf) & MPPE_BIT_FLUSHED;
- int sanity = 0;
-
- 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.
- */
- arcfour_decrypt(&state->arcfour_context, ibuf, 1, obuf);
-
- /*
- * 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. */
- arcfour_decrypt(&state->arcfour_context, ibuf + 1, isize - 1, obuf + 1);
-
- 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)
-{
- ppp_mppe_state *state = (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
- *************************************************************/
-
-/* These are in ppp.c (2.2.x) or ppp_generic.c (2.4.x) */
-extern int ppp_register_compressor (struct compressor *cp);
-extern void ppp_unregister_compressor (struct compressor *cp);
-
-/*
- * Procedures exported to if_ppp.c.
- */
-struct compressor ppp_mppe = {
- CI_MPPE, /* compress_proto */
- mppe_alloc, /* comp_alloc */
- mppe_free, /* comp_free */
- mppe_comp_init, /* comp_init */
- mppe_comp_reset, /* comp_reset */
- mppe_compress, /* compress */
- mppe_comp_stats, /* comp_stat */
- mppe_alloc, /* decomp_alloc */
- mppe_free, /* decomp_free */
- mppe_decomp_init, /* decomp_init */
- mppe_decomp_reset, /* decomp_reset */
- mppe_decompress, /* decompress */
- mppe_incomp, /* incomp */
- mppe_comp_stats, /* decomp_stat */
-};
-
-/* 2.2 compatibility defines */
-#ifndef __init
-#define __init
-#endif
-#ifndef __exit
-#define __exit
-#endif
-#ifndef MODULE_LICENSE
-#define MODULE_LICENSE(license)
-#endif
-
-int __init
-ppp_mppe_init(void)
-{
- int answer = ppp_register_compressor(&ppp_mppe);
-
- if (answer == 0)
- printk(KERN_INFO "PPP MPPE Compression module registered\n");
- return answer;
-}
-
-void __exit
-ppp_mppe_cleanup(void)
-{
- ppp_unregister_compressor(&ppp_mppe);
-}
-
-module_init(ppp_mppe_init);
-module_exit(ppp_mppe_cleanup);
-MODULE_LICENSE("BSD without advertisement clause");
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