[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>
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig
index 1958d9e..24f1691 100644
--- a/drivers/net/Kconfig
+++ b/drivers/net/Kconfig
@@ -2523,6 +2523,19 @@
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
diff --git a/drivers/net/Makefile b/drivers/net/Makefile
index 7c313cb..4cffd34 100644
--- a/drivers/net/Makefile
+++ b/drivers/net/Makefile
@@ -112,6 +112,7 @@
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) += ppp_mppe.o
obj-$(CONFIG_PPPOE) += pppox.o pppoe.o
obj-$(CONFIG_SLIP) += slip.o
diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c
index d3c9958..50430f7 100644
--- a/drivers/net/ppp_generic.c
+++ b/drivers/net/ppp_generic.c
@@ -137,13 +137,14 @@
/*
* 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_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 @@
/* 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 @@
return;
drop:
- kfree_skb(skb);
+ if (skb)
+ kfree_skb(skb);
++ppp->stats.tx_errors;
}
@@ -1552,6 +1589,9 @@
&& (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
index 0000000..1985d1b
--- /dev/null
+++ b/drivers/net/ppp_mppe.c
@@ -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
index 0000000..7a14e05
--- /dev/null
+++ b/drivers/net/ppp_mppe.h
@@ -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)
