diff options
| -rw-r--r-- | drivers/net/Kconfig | 13 | ||||
| -rw-r--r-- | drivers/net/Makefile | 1 | ||||
| -rw-r--r-- | drivers/net/ppp_generic.c | 88 | ||||
| -rw-r--r-- | drivers/net/ppp_mppe.c | 724 | ||||
| -rw-r--r-- | drivers/net/ppp_mppe.h | 86 | ||||
| -rw-r--r-- | include/linux/if_ppp.h | 7 | ||||
| -rw-r--r-- | include/linux/ppp-comp.h | 9 |
7 files changed, 902 insertions, 26 deletions
diff --git a/drivers/net/Kconfig b/drivers/net/Kconfig index 1958d9e16a3..24f1691b84f 100644 --- a/drivers/net/Kconfig +++ b/drivers/net/Kconfig @@ -2523,6 +2523,19 @@ config PPP_BSDCOMP module; it is called bsd_comp and will show up in the directory modules once you have said "make modules". If unsure, say N. +config PPP_MPPE + tristate "PPP MPPE compression (encryption) (EXPERIMENTAL)" + depends on PPP && EXPERIMENTAL + select CRYPTO + select CRYPTO_SHA1 + select CRYPTO_ARC4 + ---help--- + Support for the MPPE Encryption protocol, as employed by the + Microsoft Point-to-Point Tunneling Protocol. + + See http://pptpclient.sourceforge.net/ for information on + configuring PPTP clients and servers to utilize this method. + config PPPOE tristate "PPP over Ethernet (EXPERIMENTAL)" depends on EXPERIMENTAL && PPP diff --git a/drivers/net/Makefile b/drivers/net/Makefile index 7c313cb341b..4cffd34442a 100644 --- a/drivers/net/Makefile +++ b/drivers/net/Makefile @@ -112,6 +112,7 @@ obj-$(CONFIG_PPP_ASYNC) += ppp_async.o obj-$(CONFIG_PPP_SYNC_TTY) += ppp_synctty.o obj-$(CONFIG_PPP_DEFLATE) += ppp_deflate.o obj-$(CONFIG_PPP_BSDCOMP) += bsd_comp.o +obj-$(CONFIG_PPP_MPPE) += ppp_mppe.o obj-$(CONFIG_PPPOE) += pppox.o pppoe.o obj-$(CONFIG_SLIP) += slip.o diff --git a/drivers/net/ppp_generic.c b/drivers/net/ppp_generic.c index d3c9958b00d..50430f79f8c 100644 --- a/drivers/net/ppp_generic.c +++ b/drivers/net/ppp_generic.c @@ -137,13 +137,14 @@ struct ppp { /* * Bits in flags: SC_NO_TCP_CCID, SC_CCP_OPEN, SC_CCP_UP, SC_LOOP_TRAFFIC, - * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP. + * SC_MULTILINK, SC_MP_SHORTSEQ, SC_MP_XSHORTSEQ, SC_COMP_TCP, SC_REJ_COMP_TCP, + * SC_MUST_COMP * Bits in rstate: SC_DECOMP_RUN, SC_DC_ERROR, SC_DC_FERROR. * Bits in xstate: SC_COMP_RUN */ #define SC_FLAG_BITS (SC_NO_TCP_CCID|SC_CCP_OPEN|SC_CCP_UP|SC_LOOP_TRAFFIC \ |SC_MULTILINK|SC_MP_SHORTSEQ|SC_MP_XSHORTSEQ \ - |SC_COMP_TCP|SC_REJ_COMP_TCP) + |SC_COMP_TCP|SC_REJ_COMP_TCP|SC_MUST_COMP) /* * Private data structure for each channel. @@ -1027,6 +1028,56 @@ ppp_xmit_process(struct ppp *ppp) ppp_xmit_unlock(ppp); } +static inline struct sk_buff * +pad_compress_skb(struct ppp *ppp, struct sk_buff *skb) +{ + struct sk_buff *new_skb; + int len; + int new_skb_size = ppp->dev->mtu + + ppp->xcomp->comp_extra + ppp->dev->hard_header_len; + int compressor_skb_size = ppp->dev->mtu + + ppp->xcomp->comp_extra + PPP_HDRLEN; + new_skb = alloc_skb(new_skb_size, GFP_ATOMIC); + if (!new_skb) { + if (net_ratelimit()) + printk(KERN_ERR "PPP: no memory (comp pkt)\n"); + return NULL; + } + if (ppp->dev->hard_header_len > PPP_HDRLEN) + skb_reserve(new_skb, + ppp->dev->hard_header_len - PPP_HDRLEN); + + /* compressor still expects A/C bytes in hdr */ + len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2, + new_skb->data, skb->len + 2, + compressor_skb_size); + if (len > 0 && (ppp->flags & SC_CCP_UP)) { + kfree_skb(skb); + skb = new_skb; + skb_put(skb, len); + skb_pull(skb, 2); /* pull off A/C bytes */ + } else if (len == 0) { + /* didn't compress, or CCP not up yet */ + kfree_skb(new_skb); + new_skb = skb; + } else { + /* + * (len < 0) + * MPPE requires that we do not send unencrypted + * frames. The compressor will return -1 if we + * should drop the frame. We cannot simply test + * the compress_proto because MPPE and MPPC share + * the same number. + */ + if (net_ratelimit()) + printk(KERN_ERR "ppp: compressor dropped pkt\n"); + kfree_skb(skb); + kfree_skb(new_skb); + new_skb = NULL; + } + return new_skb; +} + /* * Compress and send a frame. * The caller should have locked the xmit path, @@ -1113,29 +1164,14 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb) /* try to do packet compression */ if ((ppp->xstate & SC_COMP_RUN) && ppp->xc_state != 0 && proto != PPP_LCP && proto != PPP_CCP) { - new_skb = alloc_skb(ppp->dev->mtu + ppp->dev->hard_header_len, - GFP_ATOMIC); - if (new_skb == 0) { - printk(KERN_ERR "PPP: no memory (comp pkt)\n"); + if (!(ppp->flags & SC_CCP_UP) && (ppp->flags & SC_MUST_COMP)) { + if (net_ratelimit()) + printk(KERN_ERR "ppp: compression required but down - pkt dropped.\n"); goto drop; } - if (ppp->dev->hard_header_len > PPP_HDRLEN) - skb_reserve(new_skb, - ppp->dev->hard_header_len - PPP_HDRLEN); - - /* compressor still expects A/C bytes in hdr */ - len = ppp->xcomp->compress(ppp->xc_state, skb->data - 2, - new_skb->data, skb->len + 2, - ppp->dev->mtu + PPP_HDRLEN); - if (len > 0 && (ppp->flags & SC_CCP_UP)) { - kfree_skb(skb); - skb = new_skb; - skb_put(skb, len); - skb_pull(skb, 2); /* pull off A/C bytes */ - } else { - /* didn't compress, or CCP not up yet */ - kfree_skb(new_skb); - } + skb = pad_compress_skb(ppp, skb); + if (!skb) + goto drop; } /* @@ -1155,7 +1191,8 @@ ppp_send_frame(struct ppp *ppp, struct sk_buff *skb) return; drop: - kfree_skb(skb); + if (skb) + kfree_skb(skb); ++ppp->stats.tx_errors; } @@ -1552,6 +1589,9 @@ ppp_receive_nonmp_frame(struct ppp *ppp, struct sk_buff *skb) && (ppp->rstate & (SC_DC_FERROR | SC_DC_ERROR)) == 0) skb = ppp_decompress_frame(ppp, skb); + if (ppp->flags & SC_MUST_COMP && ppp->rstate & SC_DC_FERROR) + goto err; + proto = PPP_PROTO(skb); switch (proto) { case PPP_VJC_COMP: diff --git a/drivers/net/ppp_mppe.c b/drivers/net/ppp_mppe.c new file mode 100644 index 00000000000..1985d1b57c4 --- /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 00000000000..7a14e058c66 --- /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) diff --git a/include/linux/if_ppp.h b/include/linux/if_ppp.h index 572aff7daa2..768372f07ca 100644 --- a/include/linux/if_ppp.h +++ b/include/linux/if_ppp.h @@ -21,7 +21,7 @@ */ /* - * ==FILEVERSION 20000724== + * ==FILEVERSION 20050812== * * NOTE TO MAINTAINERS: * If you modify this file at all, please set the above date. @@ -35,6 +35,8 @@ #ifndef _IF_PPP_H_ #define _IF_PPP_H_ +#include <linux/compiler.h> + /* * Packet sizes */ @@ -70,7 +72,8 @@ #define SC_LOG_RAWIN 0x00080000 /* log all chars received */ #define SC_LOG_FLUSH 0x00100000 /* log all chars flushed */ #define SC_SYNC 0x00200000 /* synchronous serial mode */ -#define SC_MASK 0x0f200fff /* bits that user can change */ +#define SC_MUST_COMP 0x00400000 /* no uncompressed packets may be sent or received */ +#define SC_MASK 0x0f600fff /* bits that user can change */ /* state bits */ #define SC_XMIT_BUSY 0x10000000 /* (used by isdn_ppp?) */ diff --git a/include/linux/ppp-comp.h b/include/linux/ppp-comp.h index 7227e653b3b..e86a7a5cf35 100644 --- a/include/linux/ppp-comp.h +++ b/include/linux/ppp-comp.h @@ -111,6 +111,8 @@ struct compressor { /* Used in locking compressor modules */ struct module *owner; + /* Extra skb space needed by the compressor algorithm */ + unsigned int comp_extra; }; /* @@ -191,6 +193,13 @@ struct compressor { #define DEFLATE_CHK_SEQUENCE 0 /* + * Definitions for MPPE. + */ + +#define CI_MPPE 18 /* config option for MPPE */ +#define CILEN_MPPE 6 /* length of config option */ + +/* * Definitions for other, as yet unsupported, compression methods. */ |