* RFC: [0/3] PPP MPPE module
@ 2004-06-18 16:10 Matt Domsch
2004-06-18 16:10 ` RFC: [1/3] " Matt Domsch
2004-06-18 16:12 ` RFC: [1/2] " Matt Domsch
0 siblings, 2 replies; 7+ messages in thread
From: Matt Domsch @ 2004-06-18 16:10 UTC (permalink / raw)
To: netdev, pptpclient-devel
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The pptpclient project at SourceForge has for several years maintained
the PPP MPPE (Microsoft Point-to-Point Encryption) ppp
compressor/decompressor module outside of the Linux kernel tree, as it
has needed arc4 and sha1 crypto routines which were not in-kernel
yet. As they now are, I'd like to submit this code for review, and
when deemed ready, inclusion, into 2.6.x.
MPPE is a requirement for connecting Linux clients to Linux and
Microsoft PPTP (Point to Point Tunneling Protocol) servers.
Following two emails each contain patches.
1) Add ppp_mppe.c file to drivers/net
2) minimal touches to Makefile, KConfig, ppp_generic.c, and
include/linux/ppp-comp.h
I've asked that the pptpclient-devel list be opened to posts by
non-subscribers during this review period at least.
Feedback welcome.
Thanks,
Matt
--
Matt Domsch
Sr. Software Engineer, Lead Engineer
Dell Linux Solutions linux.dell.com & www.dell.com/linux
Linux on Dell mailing lists @ http://lists.us.dell.com
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^ permalink raw reply [flat|nested] 7+ messages in thread
* RFC: [1/3] PPP MPPE module
2004-06-18 16:10 RFC: [0/3] PPP MPPE module Matt Domsch
@ 2004-06-18 16:10 ` Matt Domsch
2004-06-18 18:03 ` Stephen Hemminger
2004-06-18 16:12 ` RFC: [1/2] " Matt Domsch
1 sibling, 1 reply; 7+ messages in thread
From: Matt Domsch @ 2004-06-18 16:10 UTC (permalink / raw)
To: netdev, pptpclient-devel
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On Fri, Jun 18, 2004 at 11:10:01AM -0500, Matt Domsch wrote:
> 1) Add ppp_mppe.c file to drivers/net
--
Matt Domsch
Sr. Software Engineer, Lead Engineer
Dell Linux Solutions linux.dell.com & www.dell.com/linux
Linux on Dell mailing lists @ http://lists.us.dell.com
--- /dev/null Thu Apr 11 09:25:15 2002
+++ linux-2.6-mppe/drivers/net/ppp_mppe.c Fri Jun 18 10:42:11 2004
@@ -0,0 +1,695 @@
+/*
+ * 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.
+ *
+ * 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:
+ * 06/18/04 - Matt Domsch <Matt_Domsch@dell.com>
+ * 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/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 <asm/scatterlist.h>
+
+#include <linux/ppp_defs.h>
+#include <linux/ppp-comp.h>
+
+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);
+
+ if (sg[0].offset + length <= PAGE_SIZE) {
+ sg[0].length = length;
+ sg[1].page = 0;
+ sg[1].offset = 0;
+ sg[1].length = 0;
+ } else {
+ sg[0].length = PAGE_SIZE - sg[0].offset;
+ sg[1].length = length - sg[0].length;
+ sg[1].page = virt_to_page(address + sg[0].length);
+ sg[1].offset = offset_in_page(address + sg[0].length); /* 0 */
+ }
+}
+
+/*
+ * State for an MPPE (de)compressor.
+ */
+typedef 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;
+} 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 */
+
+#define SHA1_PAD_SIZE 40
+/*
+ * Key Derivation, from RFC 3078, RFC 3079.
+ * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
+ */
+static void GetNewKeyFromSHA(ppp_mppe_state * state, unsigned char *InterimKey)
+{
+ static const unsigned char SHApad1[SHA1_PAD_SIZE] =
+ { 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
+ };
+ static const unsigned char SHApad2[SHA1_PAD_SIZE] =
+ { 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
+ };
+ struct scatterlist sg[2];
+
+ crypto_digest_init(state->sha1);
+ setup_sg(sg, state->master_key, state->keylen);
+ crypto_digest_update(state->sha1, sg, state->keylen);
+ setup_sg(sg, SHApad1, sizeof(SHApad1));
+ crypto_digest_update(state->sha1, sg, sizeof(SHApad1));
+ setup_sg(sg, state->session_key, state->keylen);
+ crypto_digest_update(state->sha1, sg, state->keylen);
+ setup_sg(sg, SHApad2, sizeof(SHApad2));
+ crypto_digest_update(state->sha1, sg, sizeof(SHApad2));
+ crypto_digest_final(state->sha1, 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(ppp_mppe_state * state, int initial_key)
+{
+ unsigned char InterimKey[MPPE_MAX_KEY_LEN];
+ struct scatterlist sg_in[2], sg_out[2];
+
+ GetNewKeyFromSHA(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);
+ crypto_cipher_encrypt(state->arc4, sg_out, sg_in,
+ state->keylen);
+ } 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)
+{
+ 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 = (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_arc4;
+ digestsize = crypto_tfm_alg_digestsize(state->sha1);
+ if (digestsize < MPPE_MAX_KEY_LEN)
+ goto out_sha1;
+ state->sha1_digest = kmalloc(digestsize, GFP_KERNEL);
+ if (!state->sha1_digest)
+ goto out_sha1;
+
+ /* 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_sha1:
+ crypto_free_tfm(state->sha1);
+ out_arc4:
+ crypto_free_tfm(state->arc4);
+ out_free:
+ kfree(state);
+ out:
+ return NULL;
+}
+
+/*
+ * Deallocate space for a (de)compressor.
+ */
+static void mppe_free(void *arg)
+{
+ ppp_mppe_state *state = (ppp_mppe_state *) arg;
+
+ if (state) {
+ if (state->arc4)
+ crypto_free_tfm(state->arc4);
+ if (state->sha1)
+ crypto_free_tfm(state->sha1);
+ if (state->sha1_digest)
+ kfree(state->sha1_digest);
+ kfree(state);
+ }
+}
+
+/*
+ * 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;
+ struct scatterlist sg_in[2], sg_out[2];
+
+ /*
+ * 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);
+ crypto_cipher_encrypt(state->arc4, sg_out, sg_in, isize);
+
+ 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;
+ struct scatterlist sg_in[2], sg_out[2];
+
+ 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);
+ crypto_cipher_decrypt(state->arc4, sg_out, sg_in, 1);
+
+ /*
+ * 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);
+ crypto_cipher_decrypt(state->arc4, sg_out, sg_in, isize - 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
+ *************************************************************/
+
+/*
+ * 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 */
+};
+
+/*
+ * 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.
+ */
+
+int __init ppp_mppe_init(void)
+{
+ if (!(crypto_alg_available("arc4", 0) &&
+ crypto_alg_available("sha1", 0)))
+ return -ENODEV;
+
+ 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("Dual BSD/GPL");
[-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --]
^ permalink raw reply [flat|nested] 7+ messages in thread
* RFC: [1/2] PPP MPPE module
2004-06-18 16:10 RFC: [0/3] PPP MPPE module Matt Domsch
2004-06-18 16:10 ` RFC: [1/3] " Matt Domsch
@ 2004-06-18 16:12 ` Matt Domsch
2004-06-18 16:15 ` Christoph Hellwig
1 sibling, 1 reply; 7+ messages in thread
From: Matt Domsch @ 2004-06-18 16:12 UTC (permalink / raw)
To: netdev, pptpclient-devel
[-- Attachment #1: Type: text/plain, Size: 8761 bytes --]
On Fri, Jun 18, 2004 at 11:10:01AM -0500, Matt Domsch wrote:
> Following two emails each contain patches.
Of course, that subject should have been [0,1,2/2], not of 3.
> 2) minimal touches to Makefile, KConfig, ppp_generic.c, and
> include/linux/ppp-comp.h
--
Matt Domsch
Sr. Software Engineer, Lead Engineer
Dell Linux Solutions linux.dell.com & www.dell.com/linux
Linux on Dell mailing lists @ http://lists.us.dell.com
===== drivers/net/Kconfig 1.75 vs edited =====
--- 1.75/drivers/net/Kconfig 2004-06-02 15:04:38 -05:00
+++ edited/drivers/net/Kconfig 2004-06-18 09:48:16 -05:00
@@ -2410,6 +2410,12 @@
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)"
+ depends on PPP
+ ---help---
+ Support for the MPPE Encryption protocol.
+
config PPPOE
tristate "PPP over Ethernet (EXPERIMENTAL)"
depends on EXPERIMENTAL && PPP
===== drivers/net/Makefile 1.79 vs edited =====
--- 1.79/drivers/net/Makefile 2004-05-22 12:13:08 -05:00
+++ edited/drivers/net/Makefile 2004-06-18 10:22:41 -05:00
@@ -100,6 +100,7 @@
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
===== drivers/net/ppp_generic.c 1.45 vs edited =====
--- 1.45/drivers/net/ppp_generic.c 2004-04-09 18:21:06 -05:00
+++ edited/drivers/net/ppp_generic.c 2004-06-18 09:47:10 -05:00
@@ -1066,8 +1066,15 @@
/* try to do packet compression */
if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
&& proto != PPP_LCP && proto != PPP_CCP) {
- new_skb = alloc_skb(ppp->dev->mtu + ppp->dev->hard_header_len,
- GFP_ATOMIC);
+ int new_skb_size = ppp->dev->mtu + ppp->dev->hard_header_len;
+ int compressor_skb_size = ppp->dev->mtu + PPP_HDRLEN;
+
+ if (ppp->xcomp->compress_proto == CI_MPPE) {
+ /* CCP [must have] reduced MTU by MPPE_PAD. */
+ new_skb_size += MPPE_PAD;
+ compressor_skb_size += MPPE_PAD;
+ }
+ new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
if (new_skb == 0) {
printk(KERN_ERR "PPP: no memory (comp pkt)\n");
goto drop;
@@ -1079,15 +1086,27 @@
/* 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);
+ 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 {
+ } else if (len == 0) {
/* didn't compress, or CCP not up yet */
kfree_skb(new_skb);
+ } else {
+ /*
+ * (len < 0)
+ * MPPE requires that we do not send unencrypted
+ * frames. The compressor will return -1 if we
+ * should drop the frame. We cannot simply test
+ * the compress_proto because MPPE and MPPC share
+ * the same number.
+ */
+ printk(KERN_ERR "ppp: compressor dropped pkt\n");
+ kfree_skb(new_skb);
+ goto drop;
}
}
@@ -1596,7 +1615,7 @@
goto err;
if (proto == PPP_COMP) {
- ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
+ ns = dev_alloc_skb(ppp->mru + 128 + PPP_HDRLEN);
if (ns == 0) {
printk(KERN_ERR "ppp_decompress_frame: no memory\n");
goto err;
===== include/linux/ppp-comp.h 1.4 vs edited =====
--- 1.4/include/linux/ppp-comp.h 2003-08-07 18:57:19 -05:00
+++ edited/include/linux/ppp-comp.h 2004-06-18 09:46:32 -05:00
@@ -191,6 +191,100 @@
#define DEFLATE_CHK_SEQUENCE 0
/*
+ * Definitions for MPPE.
+ */
+
+#define CI_MPPE 18 /* config option for MPPE */
+#define CILEN_MPPE 6 /* length of config option */
+
+#define MPPE_PAD 8 /* 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)
+
+/*
* Definitions for other, as yet unsupported, compression methods.
*/
[-- Attachment #2: Type: application/pgp-signature, Size: 189 bytes --]
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: RFC: [1/2] PPP MPPE module
2004-06-18 16:12 ` RFC: [1/2] " Matt Domsch
@ 2004-06-18 16:15 ` Christoph Hellwig
2004-06-21 16:39 ` Matt Domsch
0 siblings, 1 reply; 7+ messages in thread
From: Christoph Hellwig @ 2004-06-18 16:15 UTC (permalink / raw)
To: Matt Domsch; +Cc: netdev, pptpclient-devel, paulus
Last time I talked to Paul on MPPE he didn't like those hacks in
the ppp core.
> --- 1.45/drivers/net/ppp_generic.c 2004-04-09 18:21:06 -05:00
> +++ edited/drivers/net/ppp_generic.c 2004-06-18 09:47:10 -05:00
> @@ -1066,8 +1066,15 @@
> /* try to do packet compression */
> if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
> && proto != PPP_LCP && proto != PPP_CCP) {
> - new_skb = alloc_skb(ppp->dev->mtu + ppp->dev->hard_header_len,
> - GFP_ATOMIC);
> + int new_skb_size = ppp->dev->mtu + ppp->dev->hard_header_len;
> + int compressor_skb_size = ppp->dev->mtu + PPP_HDRLEN;
> +
> + if (ppp->xcomp->compress_proto == CI_MPPE) {
> + /* CCP [must have] reduced MTU by MPPE_PAD. */
> + new_skb_size += MPPE_PAD;
> + compressor_skb_size += MPPE_PAD;
> + }
> + new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
> if (new_skb == 0) {
> printk(KERN_ERR "PPP: no memory (comp pkt)\n");
> goto drop;
> @@ -1079,15 +1086,27 @@
> /* 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);
> + 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 {
> + } else if (len == 0) {
> /* didn't compress, or CCP not up yet */
> kfree_skb(new_skb);
> + } else {
> + /*
> + * (len < 0)
> + * MPPE requires that we do not send unencrypted
> + * frames. The compressor will return -1 if we
> + * should drop the frame. We cannot simply test
> + * the compress_proto because MPPE and MPPC share
> + * the same number.
> + */
> + printk(KERN_ERR "ppp: compressor dropped pkt\n");
> + kfree_skb(new_skb);
> + goto drop;
> }
> }
>
> @@ -1596,7 +1615,7 @@
> goto err;
>
> if (proto == PPP_COMP) {
> - ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
> + ns = dev_alloc_skb(ppp->mru + 128 + PPP_HDRLEN);
> if (ns == 0) {
> printk(KERN_ERR "ppp_decompress_frame: no memory\n");
> goto err;
> ===== include/linux/ppp-comp.h 1.4 vs edited =====
> --- 1.4/include/linux/ppp-comp.h 2003-08-07 18:57:19 -05:00
> +++ edited/include/linux/ppp-comp.h 2004-06-18 09:46:32 -05:00
> @@ -191,6 +191,100 @@
> #define DEFLATE_CHK_SEQUENCE 0
>
> /*
> + * Definitions for MPPE.
> + */
> +
> +#define CI_MPPE 18 /* config option for MPPE */
> +#define CILEN_MPPE 6 /* length of config option */
> +
> +#define MPPE_PAD 8 /* 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)
> +
> +/*
> * Definitions for other, as yet unsupported, compression methods.
> */
>
---end quoted text---
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: RFC: [1/3] PPP MPPE module
2004-06-18 16:10 ` RFC: [1/3] " Matt Domsch
@ 2004-06-18 18:03 ` Stephen Hemminger
2004-06-18 19:31 ` [pptp-devel] " Matt Domsch
0 siblings, 1 reply; 7+ messages in thread
From: Stephen Hemminger @ 2004-06-18 18:03 UTC (permalink / raw)
To: Matt Domsch; +Cc: netdev, pptpclient-devel
Minor stuff.
> +/*
> + * State for an MPPE (de)compressor.
> + */
> +typedef 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;
> +} ppp_mppe_state;
Is the typedef really making things clearer? no.
> +/* 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 */
> +
> +#define SHA1_PAD_SIZE 40
> +/*
> + * Key Derivation, from RFC 3078, RFC 3079.
> + * Equivalent to Get_Key() for MS-CHAP as described in RFC 3079.
> + */
> +static void GetNewKeyFromSHA(ppp_mppe_state * state, unsigned char *InterimKey)
annoying RandomCaptialization
>
> +/*
> + * 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)
> +{
This can be static since only call should be through table.
> +
> +/*
> + * Decompress (decrypt) an MPPE packet.
> + */
> +int
> +mppe_decompress(void *arg, unsigned char *ibuf, int isize, unsigned char *obuf,
> + int osize)
> +{
Also can be static.
> +
> +/*************************************************************
> + * Module interface table
> + *************************************************************/
> +
> +/*
> + * 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 */
> +};
Table can be static since it is hooked in with register call.
^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: [pptp-devel] Re: RFC: [1/3] PPP MPPE module
2004-06-18 18:03 ` Stephen Hemminger
@ 2004-06-18 19:31 ` Matt Domsch
0 siblings, 0 replies; 7+ messages in thread
From: Matt Domsch @ 2004-06-18 19:31 UTC (permalink / raw)
To: Stephen Hemminger; +Cc: netdev, pptpclient-devel
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On Fri, Jun 18, 2004 at 11:03:50AM -0700, Stephen Hemminger wrote:
> Minor stuff.
All valid. I'll clean them up in the next pass.
Thanks,
Matt
--
Matt Domsch
Sr. Software Engineer, Lead Engineer
Dell Linux Solutions linux.dell.com & www.dell.com/linux
Linux on Dell mailing lists @ http://lists.us.dell.com
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^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: RFC: [1/2] PPP MPPE module
2004-06-18 16:15 ` Christoph Hellwig
@ 2004-06-21 16:39 ` Matt Domsch
0 siblings, 0 replies; 7+ messages in thread
From: Matt Domsch @ 2004-06-21 16:39 UTC (permalink / raw)
To: Christoph Hellwig, linux-ppp; +Cc: netdev, pptpclient-devel, paulus
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On Fri, Jun 18, 2004 at 05:15:58PM +0100, Christoph Hellwig wrote:
> Last time I talked to Paul on MPPE he didn't like those hacks in
> the ppp core.
Adding the linux-ppp list to the discussion.
Rather than have code in ppp_generic.c testing for CI_MPPE and doing
code conditionally (which I agree was ugly), how about adding two new
fields to struct compressor:
+ /* Extra skb space needed by the compressor algorithm */
+ unsigned int comp_skb_extra_space;
+ /* Extra skb space needed by the decompressor algorithm */
+ unsigned int decomp_skb_extra_space;
which the compressor modules can fill in if needed? Presently,
bsd_comp.c and ppp_deflate.c don't need these, so they will be filled
with zeros automatically at struct compressor instantiation.
This hunk may still be contriversial though. It adds a negative
return value to the compress() method, which is only (presently) used
by ppp_mppe (bsd_comp.c and ppp_deflate.c always return 0 if they
couldn't compress), to indicate the frame should be dropped.
- } else {
+ } else if (len == 0) {
/* didn't compress, or CCP not up yet */
kfree_skb(new_skb);
+ } else {
+ /*
+ * (len < 0)
+ * MPPE requires that we do not send unencrypted
+ * frames. The compressor will return -1 if we
+ * should drop the frame. We cannot simply test
+ * the compress_proto because MPPE and MPPC share
+ * the same number.
+ */
+ printk(KERN_ERR "ppp: compressor dropped pkt\n");
+ kfree_skb(new_skb);
+ goto drop;
Thoughts?
Patch below against 2.6.7-bk ppp_generic.c and ppp-comp.h to add such,
for comment only.
Thanks,
Matt
--
Matt Domsch
Sr. Software Engineer, Lead Engineer
Dell Linux Solutions linux.dell.com & www.dell.com/linux
Linux on Dell mailing lists @ http://lists.us.dell.com
===== drivers/net/ppp_generic.c 1.45 vs edited =====
--- 1.45/drivers/net/ppp_generic.c 2004-04-09 18:21:06 -05:00
+++ edited/drivers/net/ppp_generic.c 2004-06-21 10:56:34 -05:00
@@ -1066,8 +1066,9 @@
/* try to do packet compression */
if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0
&& proto != PPP_LCP && proto != PPP_CCP) {
- new_skb = alloc_skb(ppp->dev->mtu + ppp->dev->hard_header_len,
- GFP_ATOMIC);
+ int new_skb_size = ppp->dev->mtu + ppp->xcomp->comp_skb_extra_space + ppp->dev->hard_header_len;
+ int compressor_skb_size = ppp->dev->mtu + ppp->xcomp->comp_skb_extra_space + PPP_HDRLEN;
+ new_skb = alloc_skb(new_skb_size, GFP_ATOMIC);
if (new_skb == 0) {
printk(KERN_ERR "PPP: no memory (comp pkt)\n");
goto drop;
@@ -1079,15 +1080,27 @@
/* 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);
+ 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 {
+ } else if (len == 0) {
/* didn't compress, or CCP not up yet */
kfree_skb(new_skb);
+ } else {
+ /*
+ * (len < 0)
+ * MPPE requires that we do not send unencrypted
+ * frames. The compressor will return -1 if we
+ * should drop the frame. We cannot simply test
+ * the compress_proto because MPPE and MPPC share
+ * the same number.
+ */
+ printk(KERN_ERR "ppp: compressor dropped pkt\n");
+ kfree_skb(new_skb);
+ goto drop;
}
}
@@ -1596,7 +1609,7 @@
goto err;
if (proto == PPP_COMP) {
- ns = dev_alloc_skb(ppp->mru + PPP_HDRLEN);
+ ns = dev_alloc_skb(ppp->mru + ppp->rcomp->decomp_skb_extra_space + PPP_HDRLEN);
if (ns == 0) {
printk(KERN_ERR "ppp_decompress_frame: no memory\n");
goto err;
===== include/linux/ppp-comp.h 1.4 vs edited =====
--- 1.4/include/linux/ppp-comp.h 2003-08-07 18:57:19 -05:00
+++ edited/include/linux/ppp-comp.h 2004-06-21 10:59:44 -05:00
@@ -111,6 +111,10 @@
/* Used in locking compressor modules */
struct module *owner;
+ /* Extra skb space needed by the compressor algorithm */
+ unsigned int comp_skb_extra_space;
+ /* Extra skb space needed by the decompressor algorithm */
+ unsigned int decomp_skb_extra_space;
};
/*
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^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2004-06-21 16:39 UTC | newest]
Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2004-06-18 16:10 RFC: [0/3] PPP MPPE module Matt Domsch
2004-06-18 16:10 ` RFC: [1/3] " Matt Domsch
2004-06-18 18:03 ` Stephen Hemminger
2004-06-18 19:31 ` [pptp-devel] " Matt Domsch
2004-06-18 16:12 ` RFC: [1/2] " Matt Domsch
2004-06-18 16:15 ` Christoph Hellwig
2004-06-21 16:39 ` Matt Domsch
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