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[PPP]: add PPP MPPE encryption module 

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>
This commit is contained in:
Matt Domsch 2005-11-08 09:40:47 -08:00 committed by David S. Miller
parent 6722e78c90
commit b3f9b92a6e
7 changed files with 902 additions and 26 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

13
drivers/net/Kconfig
View File

@ -2523,6 +2523,19 @@ config PPP_BSDCOMP
module; it is called bsd_comp and will show up in the directory module; it is called bsd_comp and will show up in the directory
modules once you have said "make modules". If unsure, say N. 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 config PPPOE
tristate "PPP over Ethernet (EXPERIMENTAL)" tristate "PPP over Ethernet (EXPERIMENTAL)"
depends on EXPERIMENTAL && PPP depends on EXPERIMENTAL && PPP

1
drivers/net/Makefile
View File

@ -112,6 +112,7 @@ obj-$(CONFIG_PPP_ASYNC) += ppp_async.o
obj-$(CONFIG_PPP_SYNC_TTY) += ppp_synctty.o obj-$(CONFIG_PPP_SYNC_TTY) += ppp_synctty.o
obj-$(CONFIG_PPP_DEFLATE) += ppp_deflate.o obj-$(CONFIG_PPP_DEFLATE) += ppp_deflate.o
obj-$(CONFIG_PPP_BSDCOMP) += bsd_comp.o obj-$(CONFIG_PPP_BSDCOMP) += bsd_comp.o
obj-$(CONFIG_PPP_MPPE) += ppp_mppe.o
obj-$(CONFIG_PPPOE) += pppox.o pppoe.o obj-$(CONFIG_PPPOE) += pppox.o pppoe.o
obj-$(CONFIG_SLIP) += slip.o obj-$(CONFIG_SLIP) += slip.o

88
drivers/net/ppp_generic.c
View File

@ -137,13 +137,14 @@ struct ppp {
/* /*
* Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC, * 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 rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR.
* Bits in xstate: SC_COMP_RUN * Bits in xstate: SC_COMP_RUN
*/ */
#define SC_FLAG_BITS (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \ #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_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. * Private data structure for each channel.
@ -1027,6 +1028,56 @@ ppp_xmit_process(struct ppp *ppp)
ppp_xmit_unlock(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. * Compress and send a frame.
* The caller should have locked the xmit path, * 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 */ /* try to do packet compression */
if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0 if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
&& proto != PPP_LCP && proto != PPP_CCP) { && proto != PPP_LCP && proto != PPP_CCP) {
new_skb = alloc_skb(ppp->dev->mtu + ppp->dev->hard_header_len, if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) {
GFP_ATOMIC); if (net_ratelimit())
if (new_skb == 0) { printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n");
printk(KERN_ERR "PPP: no memory (comp pkt)\n");
goto drop; goto drop;
} }
if (ppp->dev->hard_header_len > PPP_HDRLEN) skb = pad_compress_skb(ppp, skb);
skb_reserve(new_skb, if (!skb)
ppp->dev->hard_header_len - PPP_HDRLEN); goto drop;
/* 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);
}
} }
/* /*
@ -1155,7 +1191,8 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb)
return; return;
drop: drop:
kfree_skb(skb); if (skb)
kfree_skb(skb);
++ppp->stats.tx_errors; ++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) && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0)
skb = ppp_decompress_frame(ppp, skb); skb = ppp_decompress_frame(ppp, skb);
if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR)
goto err;
proto = PPP_PROTO(skb); proto = PPP_PROTO(skb);
switch (proto) { switch (proto) {
case PPP_VJC_COMP: case PPP_VJC_COMP:

724
drivers/net/ppp_mppe.c Normal file
View File

@ -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);

86
drivers/net/ppp_mppe.h Normal file
View File

@ -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)

7
include/linux/if_ppp.h
View File

@ -21,7 +21,7 @@
*/ */
/* /*
* ==FILEVERSION 20000724== * ==FILEVERSION 20050812==
* *
* NOTE TO MAINTAINERS: * NOTE TO MAINTAINERS:
* If you modify this file at all, please set the above date. * If you modify this file at all, please set the above date.
@ -35,6 +35,8 @@
#ifndef _IF_PPP_H_ #ifndef _IF_PPP_H_
#define _IF_PPP_H_ #define _IF_PPP_H_
#include <linux/compiler.h>
/* /*
* Packet sizes * Packet sizes
*/ */
@ -70,7 +72,8 @@
#define SC_LOG_RAWIN 0x00080000 /* log all chars received */ #define SC_LOG_RAWIN 0x00080000 /* log all chars received */
#define SC_LOG_FLUSH 0x00100000 /* log all chars flushed */ #define SC_LOG_FLUSH 0x00100000 /* log all chars flushed */
#define SC_SYNC 0x00200000 /* synchronous serial mode */ #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 */ /* state bits */
#define SC_XMIT_BUSY 0x10000000 /* (used by isdn_ppp?) */ #define SC_XMIT_BUSY 0x10000000 /* (used by isdn_ppp?) */

9
include/linux/ppp-comp.h
View File

@ -111,6 +111,8 @@ struct compressor {
/* Used in locking compressor modules */ /* Used in locking compressor modules */
struct module *owner; struct module *owner;
/* Extra skb space needed by the compressor algorithm */
unsigned int comp_extra;
}; };
/* /*
@ -190,6 +192,13 @@ struct compressor {
#define DEFLATE_MAKE_OPT(w) ((((w) - 8) << 4) + DEFLATE_METHOD_VAL) #define DEFLATE_MAKE_OPT(w) ((((w) - 8) << 4) + DEFLATE_METHOD_VAL)
#define DEFLATE_CHK_SEQUENCE 0 #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. * Definitions for other, as yet unsupported, compression methods.
*/ */